When food is abundant mTOR stimulates cell division and growth.
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Daptomycin could no longer attach and halt the bacteria's cell division.
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Which process in an apple tree primarily results from cell division?
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You look at one gene, and it's associated with cell division.
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The treatment worked because mustard gas damages cells' DNA, stopping cell division.
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The cells did not divide, but completed some steps that precede cell division.
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Sex, a fight or simple cell division could be just around the corner.
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Cell division tends to slow down after the age of 200, they found.
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After that, further growth occurs by expansion in cell size, not through cell division.
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The infecting tips of the fungi's rhizomes could have low rates of cell division.
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Iron is key to red blood cells and the second is responsible for cell division.
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Enjoy: "Cell Division: Live & Up Close," Daniela Cimini and colleagues at Virginia Tech's Biocomplexity Institute.
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In this case it has leapt into a gene called cortex, which controls cell division.
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Unravelled DNA in a human lung cell that has been caught and pulled apart during cell division.
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And genes responsible for cell division may be thrown off by these changes, the study authors said.
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But where there is cell division and undifferentiated cell types, there is cancer, and this includes mollusks.
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During mitosis, or cell division, these sets of chromosomes duplicate and then split off to form new cells.
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Dr. Saccheri was surprised because cortex usually controls cell division in many organisms, not traits like wing color.
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As this lottery plays out with each new cell division, it may allow cancers to rapidly become aggressive.
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And that brings us to breast cancer, which, like any cancer, is "cell division gone bad," Dr. Lindner says.
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Genetic mutations accumulate in cells over time, and, eventually, this may lead to chaotic, out-of-control cell division.
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When the DNA unwinds in preparation for replication and cell division, the legs of the DNA ladder are broken.
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The researchers found that the virus disrupts pTBK1, a protein that helps spur cell division in the growing brain.
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This gives them time to track the development by keeping an eye on things like cell division and symmetry.
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Finally, lifestyle and environment can affect cell division rates, so, critics said, it's all part of the same mess.
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Telomeres are the tiny caps on the ends of chromosomes that protect our DNA from damage during cell division.
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And developmental signalling pathways controlling cell division and migration are often found to have become reactivated and dysregulated in cancer.
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Telomeres seem to protect our DNA from damage during cell division but, unfortunately, shorten and fray as a cell ages.
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We can lose even more -- 50 to 100 base pairs per cell division -- when our bodies are in oxidative stress.
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Those changes, they found, can be caused by a glitch that occurs during the process that copies DNA during cell division.
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Instead, it led him to AKT, a gene already well known to molecular biologists for its role in promoting cell division.
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Big Break In November, Mr. Turner uploaded a homemade rap video on cell division as extra credit for a biology class.
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Down syndrome is a genetic disorder caused when abnormal cell division results in an extra full or partial copy of chromosome 21.
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And the genes that govern cell division were disrupted as well, indicating that the cells couldn't divide to form new brain tissue.
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Among some 2900,2360 genes in the genome there are dozens which, like HER1203, can cause unwanted cell division when they go wrong.
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The thing that it does is wipe out every carbon-based life form on earth that's capable of having abnormal cell division.
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Our bones start weakening in our 30s; Alzheimer's often starts in your 60s; natural cell division leads ineluctably to mutations and disease. . . .
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They and their colleagues used a combination of imaging, modeling and genomic techniques to understand how the condensed chromosome forms during cell division.
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Because IGF-1 stimulates cells to grow and divide, lack of it is linked to a lower risk of cancer—uncontrolled cell division.
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These spindles are responsible for guiding chromosomes to the right place during the cell division process that eventually results in a live primate.
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"The flaw with their logic from the previous study persists: the correlation between stem cell division and tissue specific cancer risk," he told Gizmodo.
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The corps forms "X"s, which turn into asterisks, which turn into what looks like cell division, and then that turns into something else.
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CRISPR/Cas9 relies on machinery in the cell that's linked to cell division, so it can only be used when cells are actively replicating.
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Lucas was born with Down syndrome, a genetic disorder caused when abnormal cell division results in an extra full or partial copy of chromosome 21.
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That way the process is given as much time as possible to complete its work before the fertilised egg undergoes its first round of cell division.
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This means that when a new nucleus is injected into the embryo, the spindles are unable to guide chromosomes to the correct place during cell division.
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The exact number can vary among individuals because, when cells are duplicating their DNA before cell division, certain mistakes can insert or delete copies of gene sequences.
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In 1947 aminopterin, a chemical which messes up cell division by interrupting the metabolism of folic acid, was found to produce remissions in children with acute leukaemia.
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Valdez tells me that zinc also plays a role in immune function, wound healing, protein synthesis, DNA synthesis, cell division, and our sense of smell and taste.
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Comparing these to incidence of these cancers in the United States, the two researchers found a strong correlation between cell division and lifetime risk of each given cancer.
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The binding rules mean that when the strands separate during cell division it is possible to construct new copies of the DNA using the existing strands as templates.
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It works by sending low-intensity electric fields through the scalp, or other areas, that interfere with cell division in an effort to stop the cancer from spreading.
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An interesting discovery is that it takes approximately two gene mutations for cell division to get out of control and become cancerous—but not all mutations results in cancer.
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The 93th, which packs in Democrats, resembles an amoeba undergoing cell division, with twin bulges in Austin and San Antonio connected by a single tendril running along Highway 29.
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"We think the patterns of cell division we can capture with these movies could potentially carry information about these defects, which are hidden in just the snapshots," says Elemento.
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Kim Nasmyth, University of Oxford For elucidating the sophisticated mechanism that mediates the perilous separation of duplicated chromosomes during cell division and thereby prevents genetic diseases such as cancer.
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But Yuka is also an exceptionally pristine specimen, and even her cells were not able to complete cell division—a major hurdle that scientists must clear to accomplish de-extinction.
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Cancer cells with the so-called BRCA mutation have a diminished ability to restore their DNA when it gets damaged during cell division, which is a driver behind cancerous mutations.
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Early in the new year, 1939, back in the laboratory in Copenhagen where he was working, Frisch asked an American biologist, William Arnold, what the English term was for cell division.
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However, they were unable to prove if these cells were functional, or if they were truly capable of meiosis—a type of cell division critical to the formation of functional sperm cells.
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By injecting the gene editing system before the first cell division, the researchers discovered that mosaicism — a characteristic of embryos that have a mix of edited and unedited cells — could be avoided.
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Two other scientific essays — one on cell division in the body and another on evolution — are stored in the museum's archives in Fulton, Mr. Riley, the museum director, said in an interview.
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In the wake of their discovery, Jülicher assigned his new student, Zwicker, the task of unraveling the physics of centrosomes, organelles involved in animal cell division that also seemed to behave like droplets.
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As ambient music plays, and videos suggesting cell division unspool, small engines with cameras attached run around the tracks, sometimes projecting images of the translucent tunnels and culverts they pass around and through.
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He tested the hypothesis that this was due to the number of cells against alternatives, such as possible hormonal differences in taller people, which could lead to an increased rate of cell division.
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The visible aging processes and physiological signs like cell division might happen at a slower rate, possibly due to genetic factors—he pointed out that really old folks generally look younger throughout their life.
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The team also created a cell division detector to track when, where and which cells divide, as well as a tool that portrays a virtual "average" mouse embryo by aligning four of the samples.
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In a collection of clips posted to her Instagram Story on Wednesday, the Good Bones star revealed that the one embryo she had unfortunately "did not get bigger" following its fertilization process and initial cell division.
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Astra said on Wednesday its Lynparza drug, which blocks a cancer's ability to repair its genetic code during cell division, was shown to slow the progression of ovarian cancer that has started to spread in the body.
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The findings challenge the results of a 21 report in the journal Science that attributed many cancers simply to the bad luck of mutations during cell division, according to the authors of the new report in JAMA Oncology.
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This psychedelic video is a frog cell, and rippling across it traveling in waves is protein activity, which help get the cell ready for future cell division, which, believe it or not, is exactly what&aposs happening here.
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Derived from a female egg, the stem cells are the first human cells known to be capable of cell division with just one copy of the parent cell's genome, according to a study appearing on Wednesday in the journal Nature.
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Instead of just learning from researchers who spend their days dividing cells in a lab or churning out code in front of a computer, you can take classes with people who study the most effective methods for teaching cell division and JavaScript.
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In the rats with high fitness in this study, the mTOR networks typically produced biochemical signals that tell cells to avoid dividing much, while in the rats with low fitness, the mTOR networks pumped out messages that would generally promote cell division.
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" Another product from Greenroads Health claimed that "CBD [has] anti-proliferative properties that inhibit cell division and growth in certain types of cancer, not allowing the tumor to grow" and could treat "asthma, Alzheimer's disease, arthritis, autism, bipolar disorder and various types of cancer.
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"The fact that we were able to show a correlation [between stem cell division and tissue specific cancer risk]...en par with the United States is an important step forward, but it's not really the most important point [of the updated study]", said Tomasetti.
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The researchers found that the more often cells of a certain tissue divide, the more likely it is that the tissue will develop cancer, and said that two-thirds of the difference in cancer rates among different tissues comes from those differences in cell division.
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The experiment showed that meiosis, the special process of cell division and genetic rearrangement required to form germ cells (sperm and eggs), can be achieved in the lab by treating stem cells with a cocktail of chemicals and hormones in the presence of testicular tissue.
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Biologists often view cancer primarily as a genetic program gone wrong, with mutations and epigenetic changes producing cells that don't behave the way they should: Genes associated with cell division and growth may be turned up, and genes for programmed cell death may be turned down.
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Lawmakers voted 20-12 in favor of the law, which criminalizes abortion if the physician has knowledge that the procedure is being sought due to a diagnosis of Down syndrome, a genetic disorder caused when abnormal cell division results in an extra full or partial copy of chromosome 21.
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The new study, co-led by Jiahao Sha and Qi Zhou, is the first to demonstrate that it's possible to push embryonic stem cells through meiosis (cell division) to produce a functional gamete, with apparently correct nuclear DNA and chromosomal content, and the ability to produce viable offspring.
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These researchers, typically molecular biologists by training, have turned to metabolism and the Warburg effect because their own research led each of them to the same conclusion: A number of the cancer-causing genes that have long been known for their role in cell division also regulate cells' consumption of nutrients.
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Many of these proteins are involved in regulating cellular activity, including growth and cell division (the things that go wrong in cancer), via signalling pathways in which one protein changes the behaviour of others (sometimes hundreds or thousands of others), each of which then changes the behaviour of others still—and so on.
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These included ATR, which detects damage to DNA and halts the cycle of cell division that cancer-promoting mutations encourage; AMER1, which stifles cell growth; and RECK, which reins in metastasis, the tendency of cancer cells to peel off their natal tumour and wander around the body looking for other sites to colonise.
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The researchers used genome sequencing to look at the mutations responsible for abnormal cell growth in 17 types of cancer and compared it to data collected from cancer patients in 69 countries, including the US. They sought to assign the proportions of mutations to one of three factors: cell division, lifestyle and environment, and heredity.
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Other researchers say the intense and prolonged physical exertion of a game like tennis may fend off cancer by slowing the decline of your telomeres, the tiny caps on the ends of your DNA strands that tend to shorten and fray with age, and leave the DNA subject to greater risk of mutation during cell division and replication.
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But shocker: This new paper is already getting criticism for some of the same reasons as the first one did, namely that it doesn't take into account that lifestyle and environment can affect cell division rates, but also because the paper makes conclusions about cancer as a whole, even though cancer is really a collection of many distinct diseases.
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And there was the restless physicality of the genome, the way it arranged itself during cell division into 23 spindly pairs of chromosomes that could be stained and studied under a microscope, and then somehow, when cell replication was through, merged back together into a baffling, ever-wriggling ball of chromatin — DNA wrapped in a protective packaging of histone proteins.
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Other companies have relied on fetal bovine serum or Chinese hamster ovaries to stimulate cell division and production, but Meatable says it has developed a process where it can sample tissue from an animal, revert that tissue to a pluripotent stem cell, then culture that cell sample into muscle and fat to produce the pork products that palates around the world crave.
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" The group doesn't go into too much detail on the website for the project, which is called Hy (an abbreviation of "harmony"), but a press release accompanying the announcement explains that they chose certain bandwidth and frequency ranges that are supposed to generate "improvements in growth, biomass, stomata (which favors water absorption and light use), and favoring cell division, fluids in cell walls, and protective enzymes.
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3 types of cell division are known to exist within AAPB, 2 daughter-cell division, 4 daughter-cell division, and the non-typical 3 daughter-cell division, commonly referred to as Y-cell division. AAPB are usually pink or orange in color when isolated from water.Nianzhi, Jiao; Sieracki, Michael E.; Yao, Zhang; and Hailian, DU. (2003). Aerobic anoxygenic phototrophic bacteria and their roles in marine ecosystems.
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Cell division orientation is the direction along which the new daughter cells are formed. Cell division orientation is important for morphogenesis, cell fate and tissue homeostasis. Abnormalities in the cell division orientation leads to the malformations during development and cancerous tissues. Factors that influence cell division orientation are cell shape, anisotropic localization of specific proteins and mechanical tensions.
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Mitotic cell division enables sexually reproducing organisms to develop from the one-celled zygote, which itself was produced by meiotic cell division from gametes. After growth, cell division by mitosis allows for continual construction and repair of the organism. The human body experiences about 10 quadrillion cell divisions in a lifetime. The primary concern of cell division is the maintenance of the original cell's genome.
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When the drug was introduced, cell division stopped and colony formation resulted through cell-cell aggregation. When the drug was removed, cell-division dominated once again.
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Muse cells proliferate at a speed of ~1.3 day/cell division in adherent culture. This is slightly slower than that of human fibroblasts (~1 day/cell division).
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Numerous descriptions of cell division were made during 18th and 19th centuries, with various degrees of accuracy. In 1835, the German botanist Hugo von Mohl, described cell division in the green alga Cladophora glomerata, stating that multiplication of cells occurs through cell division."Notes and memoranda: The late professor von Mohl". Quarterly Journal of Microscopical Science, v.
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Cell division in prokaryotes (binary fission) and eukaryotes (mitosis and meiosis) Cell division is the process by which a parent cell divides into two or more daughter cells. Cell division usually occurs as part of a larger cell cycle. In eukaryotes, there are two distinct types of cell division: a vegetative division, whereby each daughter cell is genetically identical to the parent cell (mitosis), and a reproductive cell division, whereby the number of chromosomes in the daughter cells is reduced by half to produce haploid gametes (meiosis). In cell biology, mitosis (/maɪˈtoʊsɪs/) is a part of the cell cycle, in which, replicated chromosomes are separated into two new nuclei.
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MAP4 has also been linked to the process of cell division.
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Kinetin (/'kaɪnɪtɪn/) is a type of cytokinin, a class of plant hormone that promotes cell division. Kinetin was originally isolated by Miller and Skoog et al. as a compound from autoclaved herring sperm DNA that had cell division- promoting activity. It was given the name kinetin because of its ability to induce cell division, provided that auxin was present in the medium.
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In addition, cell division in normal, non- cancerous cells is tightly controlled. In cancer cells, these processes are deregulated because the proteins that control them are altered, leading to increased growth and cell division within the tumor.
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The term asymmetric cell division usually refers to such intrinsic asymmetric divisions.
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In general, nondisjunction can occur in any form of cell division that involves ordered distribution of chromosomal material. Higher animals have three distinct forms of such cell divisions: Meiosis I and meiosis II are specialized forms of cell division occurring during generation of gametes (eggs and sperm) for sexual reproduction, mitosis is the form of cell division used by all other cells of the body.
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JAK-STAT signalling plays an important role in animal development. The pathway can promote blood cell division, as well as differentiation (the process of a cell becoming more specialised). In some flies with faulty JAK genes, too much blood cell division can occur, potentially resulting in leukaemia. JAK-STAT signalling has also been associated with excessive white blood cell division in humans and mice.
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Multicellular organisms replace worn-out cells through cell division. In some animals, however, cell division eventually halts. In humans this occurs, on average, after 52 divisions, known as the Hayflick limit. The cell is then referred to as senescent.
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The results demonstrated that ADEP is perturbing bacterial cell division. To identify the reason why ADEP inhibited cell division, researchers monitored septum formation and nucleoid segregation in ADEP B. subtilis and ADEP S. aureus. The S. aureus and B. subtilis samples gave equivalent results. This part showed the importance of wild type of ClpP and inhibition of septum formation is by direct interference of ADEP with the cell division components.
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Cell division in eukaryote is much more complicated than procaryote. Depending upon chromosomal number reduced or not; Eukaryotic cell divisions can be classified as Mitosis (equational division) and Meiosis (reductional division). A premitive form of cell division is also found which is called amitosis. The amitotic or mitotic cell division is more atypical and diverse in the various groups of organisms such as protists (namely diatoms, dinoflagellates etc) and fungi.
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Abnormal levels of cyclin D-1 may promote rapid cell division in epithelioid sarcoma.
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By sequestering FtsZ, the cell can directly link DNA damage to inhibiting cell division.
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Cyclin F help to control NUSAP abundance and is therefore essential to proper cell division.
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Folate is especially important during periods of frequent cell division and growth, such as infancy and pregnancy. Folate deficiency hinders DNA synthesis and cell division, affecting hematopoietic cells and neoplasms the most because of their greater frequency of cell division. RNA transcription and subsequent protein synthesis are less affected by folate deficiency, as the mRNA can be recycled and used again (as opposed to DNA synthesis, where a new genomic copy must be created).
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Divisome and elongasome complexes responsible for peptidoglycan synthesis during lateral cell-wall growth and division. Bacterial cell division happens through binary fission or budding. The divisome is a protein complex in bacteria that is responsible for cell division, constriction of inner and outer membranes during division, and peptidoglycan (PG) synthesis at the division site. A tubulin like protein, FtsZ plays a critical role in formation of a contractile ring for the cell division.
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Normal cell division—mitosis—has checkpoints that keep cell division under control. Some of the proteins that control this cycle are called cdk2 (CDKs). Overexpression of HER2 sidesteps these checkpoints, causing cells to proliferate in an uncontrolled fashion. This is caused by phosphorylation by Akt.
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150 Years of cell division. Dermatopathology: Practical & Conceptual, Vol. 8, No. 2. link In animal cells, cell division with mitosis was discovered in frog, rabbit, and cat cornea cells in 1873 and described for the first time by the Polish histologist Wacław Mayzel in 1875.
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It investigates how cilia length and dynamics impact the speed of cell division and tissue development.
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Cell division cycle 26 is a protein that in humans is encoded by the CDC26 gene.
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Cell division does not proceed until the daughter cells reach their mature size and original shape.
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Cell division, growth & proliferation Cell proliferation is the process by which a cell grows and divides to produce two daughter cells. Cell proliferation leads to an exponential increase in cell number and is therefore a rapid mechanism of tissue growth. Cell proliferation requires both cell growth and cell division to occur at the same time, such that the average size of cells remains constant in the population. Cell division can occur without cell growth, producing many progressively smaller cells (as in cleavage of the zygote, while cell growth can occur without cell division to produce a single larger cell (as in growth of neurons).
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This complex is more stable and has a higher specific activity than any of the lower molecular weight forms. Recombinant TK1 cannot be activated and converted to a tetramer in this way, showing that the enzyme occurring in cells has been modified after synthesis. TK1 is synthesized by the cell during the S phase of cell division. After cell division is completed, TK1 is degraded intracellularly and does not pass to body fluids after normal cell division.
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During any of the life stages it is possible for Tetraselmis species to undergo a complete transformation and develop flagella, becoming motile. Tetraselmis species undergo cell division during the non-motile stage, producing two daughter cells, and most species only undergo one division cycle. During cell division, organelles divide synchronously before nuclear division. Cell division is aided by a phycoplast, which is a microtubule structure that helps the cell divide the nuclei into each daughter cell.
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Cell division protein kinase 10 is an enzyme that in humans is encoded by the CDK10 gene.
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Cell division protein kinase 8 is an enzyme that in humans is encoded by the CDK8 gene.
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Cell division protein kinase 3 is an enzyme that in humans is encoded by the CDK3 gene.
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The elongation enzymes then disassemble, and the two "daughter" chromosomes are resolved before cell division is completed.
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This interference results in abnormal cell division. The abnormal microtubules affect cell wall formation as well as chromosome replication and division. The key difference between DCPA and other mitotic inhibitors is that it often produces multinucleate cells. It essentially kills plants by inhibiting cell division in this manner.
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Cell division cycle protein 123 homolog is a protein that in humans is encoded by the CDC123 gene.
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Cell division cycle-associated protein 3 is a protein that in humans is encoded by the CDCA3 gene.
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When overexpressed, DpiA can interrupt DNA replication and induce the SOS response resulting in inhibition of cell division.
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Such DNA mutations and uncontrolled cell division resulting from exposure to sidestream smoke may result in cancerous tumours.
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Cell division cycle protein 27 homolog is a protein that in humans is encoded by the CDC27 gene.
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Cell division cycle 5-like protein is a protein that in humans is encoded by the CDC5L gene.
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Cell division cycle protein 16 homolog is a protein that in humans is encoded by the CDC16 gene.
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The Hydra regulates the population of the Chlorella algae by digesting excess algae or controlling algal cell division.
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Kurt Michel with his phase-contrast microscope A cell division under microscope was first discovered by German botanist Hugo von Mohl in 1835 as he worked over the green alga Cladophora glomerata. In 1943, cell division was filmed for the first time by Kurt Michel using a phase-contrast microscope.
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Cell division cycle-associated 7-like protein is a protein that in humans is encoded by the CDCA7L gene.
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These mosses still undergo the same cell division patterns in capsule development, but the teeth do not fully develop.
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The vitelloplasm contains mostly yolk platelets. Only the teloplasm gets passed onto the daughter stem cells after cell division.
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These mosses still undergo the same cell division patterns in capsule development, but the teeth do not fully develop.
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The common features of global response are induction of multiple genes, cell cycle arrest, and inhibition of cell division.
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His earliest publications focused on the isolation of temperature sensitive yeast mutants disabled in basic biological processes, including DNA, RNA and protein synthesis. This led to the identification of the CDC (Cell Division Cycle) genes, which function in promoting the progression through cell division, most notably CDC28, which encodes the yeast Cdk kinase. Other significant discoveries include introduction of the concept of cell cycle "checkpoints", which delay cell division when cellular insults are generated and also the identification and characterization of the mating signal transduction pathway.
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The relationship between cell size and cell division has been extensively studied in yeast. For some cells, there is a mechanism by which cell division is not initiated until a cell has reached a certain size. If the nutrient supply is restricted (after time t = 2 in the diagram, below), and the rate of increase in cell size is slowed, the time period between cell divisions is increased. Yeast cell-size mutants were isolated that begin cell division before reaching a normal/regular size (wee mutants).
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Fish embryos go through a process called mid-blastula transition which is observed around the tenth cell division in some fish species. Once zygotic gene transcription starts, slow cell division begins and cell movements are observable. During this time three cell populations become distinguished. The first population is the yolk syncytial layer.
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Nerve fibers are cell processes Nerve fibers are outgrowths of nerve cells. Cell division Nerve cells are generated by cell division. Contact Nerve cells are connected by sites of contact and not cytoplasmic continuity. Waldeyer himself was neutral on this point, and strictly speaking the neuron doctrine does not depend upon this element.
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Cell division cycle and apoptosis regulator protein 1 is a protein that in humans is encoded by the CCAR1 gene.
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The main function of centrioles is to produce cilia during interphase and the aster and the spindle during cell division.
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Vulpinic acid has some antibacterial activity against gram-positive bacteria, and has been shown to disrupt cell division in MRSA.
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This postulation was confirmed when Jin et al. employed Cdc2AF, an unphosphorylatable mutant of Cdk1, and saw accelerated entry to cell division due to the nuclear localization of the cyclin B. Therefore, nuclear localization of cyclin B is necessary but not sufficient to trigger cell division. In investigation of cell cycle regulation, Jin et al.
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The last stage of the cell division process is cytokinesis. In this stage there is a cytoplasmic division that occurs at the end of either mitosis or meiosis. At this stage there is a resulting irreversible separation leading to two daughter cells. Cell division plays an important role in determining the fate of the cell.
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FtsZ is a protein encoded by the ftsZ gene that assembles into a ring at the future site of bacterial cell division. FtsZ is a prokaryotic homologue of the eukaryotic protein tubulin. The initials FtsZ mean "Filamenting temperature- sensitive mutant Z." The hypothesis was that cell division mutants of E. coli would grow as filaments due to the inability of the daughter cells to separate from one another. FtsZ is found in almost all bacteria, many archaea, all chloroplasts and some mitochondria, where it is essential for cell division.
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Most other cells cannot divide indefinitely as after a few cycles of cell division the cells stop expressing an enzyme telomerase. The genetic material, in the form of deoxyribonucleic acid (DNA), continues to shorten with each cell division, and cells eventually stop dividing when they sense that their DNA is critically shortened. However, this enzyme in "youthful" cells replaces these lost bits (nucleotides) of DNA, thus making almost unlimited cycles of cell division possible. It is believed that the above-mentioned tissues have a constitutional elevated expression of telomerase.
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To ensure self-renewal, stem cells undergo two types of cell division (see Stem cell division and differentiation diagram). Symmetric division gives rise to two identical daughter stem cells, whereas asymmetric division produces one stem cell and one progenitor cell with limited self- renewal potential. Progenitors can go through several rounds of cell division before finally differentiating into a mature cell. It is believed that the molecular distinction between symmetric and asymmetric divisions lies in differential segregation of cell membrane proteins (such as receptors) and their associated proteins between the daughter cells.
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FtsK has been shown to be a part of the divisome of bacteria and couple cell division with the resolution of dimers. FtsKN is thought to both stabilize the septum and aid in the recruitment of other proteins to the site of cell division. Recent research has shed light on the role of FtsK in membrane synthesis and has discovered that the L-domain is also important in the building of the septum. There is evidence to suggest that the N terminus is not the only part of FtsK that is involved in cell division.
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After cell division is completed, TK1 is degraded intracellularly, so that it does not pass into body fluids after normal cell division. The TK enzyme suggested as a tumor marker is the cytosolic cell cycle dependent TK1. It is present during cell division in much higher concentrations than TK2 and it is released in quantities that completely dominate the thymidine kinase activity in blood and other body fluids. In addition to cellular TKs, virus specific thymidine kinases have been identified in Herpes simplex virus, Varicella zoster virus and Epstein-Barr virus.
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This suggests that cell division may be regulated in part by dilution of Wee1 protein in cells as they grow larger.
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ConA can also initiate cell division (mitogenesis), primarily acting on T-lymphocytes, by stimulating their energy metabolism within seconds of exposure.
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Cell division control protein 42 homolog, also known as Cdc42, is a protein involved in regulation of the cell cycle. It was originally identified in S. cerevisiae (yeast) as a mediator of cell division, and is now known to influence a variety of signaling events and cellular processes in a variety of organisms from yeast to mammals.
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Siphonocladus tropicus showing segregative cell division. Siphonocladus is a small genus of green algae in the family Siphonocladaceae.See the NCBI webpage on Siphonocladus. Data extracted from the The algal body (thallus) is composed of long, club-shaped cells that divide by segregative cell division, followed by the formation of branches that break through the mother cell.
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Numb (blue) is asymmetrically distributed within the neuroblast. Following cell division, the GMC contains the Numb protein which suppresses Notch signaling. The other daughter cell is receptive to Notch signaling, causing distinct cellular responses, and ultimately two distinct cell fates between the daughter cells. In Drosophila melanogaster, asymmetric cell division plays an important role in neural development.
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Members of some genera are identifiable by the way cells are attached to one another: in pockets, in chains, or grapes like clusters. These arrangements reflect patterns of cell division and the fact that cells stick together. Sarcina cells, for example, are arranged in cubical pockets because cell division alternates regularly among the three perpendicular planes. Streptococcus spp.
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The bacterial cell cycle is divided into three stages. The B period occurs between the completion of cell division and the beginning of DNA replication. The C period encompasses the time it takes to replicate the chromosomal DNA. The D period refers to the stage between the conclusion of DNA replication and the end of cell division.
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This is the first step and the rate-limiting step in humans for the production of polyamines, compounds required for cell division.
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The cells undergo cell division in one of two ways, either by binary fission or by unequal binary fission (Bass et al., 2012).
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Pathologic hyperplasia is an abnormal increase in cell division. A common pathologic hyperplasia in women occurs in the endometrium and is called endometriosis.
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Most human cells are produced by mitotic cell division. Important exceptions include the gametes – sperm and egg cells – which are produced by meiosis.
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These axopods adhere to passing prey and assist with cell movement, as well as playing a part in cell division and cell fusion.
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Screens developed using small RNAs have been used to identify genes involved in fundamental processes such as cell division, apoptosis and fat regulation.
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Cell division cycle 23 homolog (S. cerevisiae), also known as CDC23, is a protein that, in humans, is encoded by the CDC23 gene.
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This is to prevent the stopping of cell division in eukaryotic organisms, or even withdrawing from the basic reproduction procedures of eukaryotic cells.
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Mitosis is the normal process in eukaryotes for cell division; duplicating chromosomes and segregating one of the two copies into each of the two daughter cells, in contrast with meiosis. The mitosis theory states that meiosis evolved from mitosis. According to this theory, early eukaryotes evolved mitosis first, became established, and only then did meiosis and sexual reproduction arise. Supporting this idea are observations of some features, such as the meiotic spindles that draw chromosome sets into separate daughter cells upon cell division, as well as processes regulating cell division that employ the same, or similar molecular machinery.
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Besides ORF1 and ORF2, there is also an ORF3 which is not necessarily required for PCV to survive within the host. Research has shown that the protein coded in ORF3 can modulate the host cell's cell- division cycle and cause cell-mediated, virus-induced apoptosis. Using a yeast two-hybrid screening system of ORF3 against the porcine cDNA library indicated that the ORF3 protein interacts with the porcine pPirh2, which is an E3 ubiquitin ligase. This E3 ubiquitin ligase normally interacts with p53 during the cell division cycle and prevents it from halting the cell division cycle at S-phase.
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In Euryarchaeota the cell division protein FtsZ, which forms a contracting ring around the cell, and the components of the septum that is constructed across the center of the cell, are similar to their bacterial equivalents. In cren- and thaumarchaea, the cell division machinery Cdv fulfills a similar role. This machinery is related to the eukaryotic ESCRT-III machinery which, while best known for its role in cell sorting, also has been seen to fulfill a role in separation between divided cell, suggesting an ancestral role in cell division. Both bacteria and eukaryotes, but not archaea, make spores.
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In most cases, isochromosomes of 9p contain two centromeres, called a dicentric chromosome. The tetrasomy can also be formed independently of cell division. Double stranded breaks in the short arm of chromosome 9 may be repaired incorrectly, resulting in the formation of an isochromosome of 9p with a single centromere. This isochromosome can then be passed on during cell division.
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Amitosis (a- + mitosis), also called 'karyostenosis' or direct cell division or binary fission. It is cell proliferation that does not occur by mitosis, the mechanism usually identified as essential for cell division in eukaryotes. The polyploid macronucleus found in ciliates divides amitotically. While normal mitosis results in a precise division of parental alleles, amitosis results in a random distribution of parental alleles.
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The circadian gating of cell division may be a protective feature to prevent division at a vulnerable phase. Phases in which KaiC has high ATPase activity do not allow for cell division to take place. In mutants with constantly elevated KaiC ATPase activity, the protein CikA is absent. CikA is a major factor in the input pathway and causes KaiC dependent cell elongation.
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Cancer cells are created when the genes responsible for regulating cell division are damaged. Carcinogenesis is caused by mutation and epimutation of the genetic material of normal cells, which upsets the normal balance between proliferation and cell death. This results in uncontrolled cell division in the body. The uncontrolled and often rapid proliferation of cells can lead to benign or malignant tumours (cancer).
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Centromere/kinetochore protein zw10 homolog is a protein that in humans is encoded by the ZW10 gene. This gene encodes a protein that is one of many involved in mechanisms to ensure proper chromosome segregation during cell division. The encoded protein binds to centromeres during the prophase, metaphase, and early anaphase cell division stages and to kinetochore microtubules during metaphase.
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Nevertheless, high EPA levels in S. violacea have been correlated with greater rates of cell division in high pressures as well as in low temperatures.Kawamoto, Jun et al. "Favourable effects of eicosapentaenoic acid on the late step of the cell division in a piezophilic bacterium, Shewanella violacea DSS12, at high-hydrostatic pressures." Environmental Microbiology 13(8) (2011): 2293-298. Print.
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As early as 1998, O. tauri was identified as "a good candidate for biological models such as cell division and/or genome sequencing studies".
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Mammalian embryogenesis is the process of cell division and cellular differentiation during early prenatal development which leads to the development of a mammalian embryo.
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This inhibition was shown to not only alter the lipid composition of the plasma-membrane, but also impact cell division and growth, in plants.
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Her technique has found its way into other labs who are also interested in how particular proteins contribute to different stages of cell division.
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The region of cell division includes the apical meristem and the primary meristems the protoderm, ground meristem, and procambium derived from the apical meristem.
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The fungus infects the ovaries causing a pseudo-pollination and an enhanced cell division, resulting in the infested fruit being larger than the healthy one.
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Curacin A has been shown to interact with colchicine binding sites on tubulin, which inhibits microtubule polymerization, an essential process for cell division and proliferation.
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Like seedlings, adult plant shade avoidance involves several mechanisms acting together. Petiole elongation is both a result of cell expansion and cell division, though not at the same stage in petiole and leaf formation. In newly growing leaves, cell division is the primary factor, while fully formed leaves and petioles rely on cell expansion. Xyloglucan endotransglucosylase/hydrolases (XTHs) are a family of cell wall modifying proteins.
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Movements of the microtubules are based on the actions of the centrosome. Each daughter cell after the cessation of mitosis contains one primary MTOC. Before cell division begins, the interphase MTOC replicates to form two distinct MTOCs (now typically referred to as centrosomes). During cell division, these centrosomes move to opposite ends of the cell and nucleate microtubules to help form the mitotic/meiotic spindle.
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Hermann Fol continued Hertwig's research by testing the effects of injecting several spermatozoa into an egg, and found that the process did not work with more than one spermatozoon. Flemming began his research of cell division starting in 1868. The study of cells was an increasingly popular topic in this time period. By 1873, Schneider had already begun to describe the steps of cell division.
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The M phase has been broken down into several distinct phases, sequentially known as prophase, prometaphase, metaphase, anaphase and telophase leading to cytokinesis. Cell division is more complex in eukaryotes than in other organisms. Prokaryotic cells such as bacterial cells reproduce by binary fission, a process that includes DNA replication, chromosome segregation, and cytokinesis. Eukaryotic cell division either involves mitosis or a more complex process called meiosis.
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The principal mechanism of action of the taxane class of drugs is the disruption of microtubule function. Microtubules are essential to cell division, and taxanes stabilize GDP-bound tubulin in the microtubule, thereby inhibiting the process of cell division as depolymerization is prevented. Thus, in essence, taxanes are mitotic inhibitors. In contrast to the taxanes, the vinca alkaloids prevent mitotic spindle formation through inhibition of tubulin polymerization.
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Molecular structure of DNA Self-replication is any behavior of a dynamical system that yields construction of an identical or similar copy of itself. Biological cells, given suitable environments, reproduce by cell division. During cell division, DNA is replicated and can be transmitted to offspring during reproduction. Biological viruses can replicate, but only by commandeering the reproductive machinery of cells through a process of infection.
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FtsZ, the first identified prokaryotic cytoskeletal element, forms a filamentous ring structure located in the middle of the cell called the Z-ring that constricts during cell division, similar to the actin-myosin contractile ring in eukaryotes. The Z-ring is a highly dynamic structure that consists of numerous bundles of protofilaments that extend and shrink, although the mechanism behind Z-ring contraction and the number of protofilaments involved are unclear. FtsZ acts as an organizer protein and is required for cell division. It is the first component of the septum during cytokinesis, and it recruits all other known cell division proteins to the division site.
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Inhibition of FtsZ disrupts septum formation, resulting in filamentation of bacterial cells (top right of electron micrograph). During cell division, FtsZ is the first protein to move to the division site, and is essential for recruiting other proteins that produce a new cell wall (septum) between the dividing cells. FtsZ's role in cell division is analogous to that of tubulin in eukaryotic cell division, but, unlike the actin-myosin ring in eukaryotes, FtsZ has no known motor protein associated with it. The origin of the cytokinetic force, thus, remains unclear, but it is believed that the localized synthesis of new cell wall produces at least part of this force.
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During early embryonic development (cleavage of the zygote to form a morula and blastoderm), cell divisions occur repeatedly without cell growth. Conversely, some cells can grow without cell division or without any progression of the cell cycle, such as growth of neurons during axonal pathfinding in nervous system development. Cell division without cell growth during embryonic cleavage In multicellular organisms, tissue growth rarely occurs solely through cell growth without cell division, but most often occurs through cell proliferation. This is because a single cell with only one copy of the genome in the cell nucleus can perform biosynthesis and thus undergo cell growth at only half the rate of two cells.
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A common pharmacological inhibitor for adult neurogenesis is methylazoxymethanol acetate (MAM), a chemotherapeutic agent. Other cell division inhibitors commonly used in studies are cytarabine and temozolomide.
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Its inactivation revealed its role directing alternations in cell division timing, growth polarity, as well as cell-specific gene expression, ultimately affecting organogenesis and cell differentiation.
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Tumor Treating Fields is a novel FDA-approved cancer treatment therapy that uses alternating electric field to disturb the rapid cell division exhibited by cancer cells.
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Kinesins, such as KIF4A, are microtubule-based motor proteins that generate directional movement along microtubules. They are involved in many crucial cellular processes, including cell division.
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Cancer drugs that interfere with cancerous growth by altering microtubules (which are necessary for cell division) damage nerves because the microtubules are necessary for axonal transport.
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In 40-50% of cases, the disorder has been linked with germline mutations in the CDKN2A gene, which codes for p16 (a regulator of cell division).
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While in the first case oriented cell division acts as active contributor to the morphogenesis, the latter case is a passive response to the external mechanical tensions.
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Bahler, J. et al. Role of polo kinase and Mid1p in determining the site of cell division in fission yeast. J. Cell Biol. 143, 1603–1616 (1998).
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ORC6 has been shown to interact with MCM5, ORC2, Replication protein A1, ORC4, DBF4, ORC3, CDC45-related protein, MCM4 and Cell division cycle 7-related protein kinase.
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In the broad sense, most chemotherapeutic drugs work by impairing mitosis (cell division), effectively targeting fast-dividing cells. As these drugs cause damage to cells, they are termed cytotoxic. They prevent mitosis by various mechanisms including damaging DNA and inhibition of the cellular machinery involved in cell division. One theory as to why these drugs kill cancer cells is that they induce a programmed form of cell death known as apoptosis.
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In an effort to study the ordered events of the cell cycle, Leland Hartwell et al. screened for and characterized temperature sensitive mutants, also known as cell division cycle mutants (cdc mutants), that display arrested cellular development at various stages of the cycle.Hartwell, L. H. "Genetic Control of the Cell-Division Cycle in Yeast, I. Detection of Mutants." Proceedings of the National Academy of Sciences 66.2 (1970): 352-59.
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Gönczy, P. and Rose, L.S. Asymmetric cell division and axis formation in the embryo (October 15, 2005), WormBook, ed. The C. elegans Research Community, WormBook, Following this first asymmetric division, the AB daughter cell divides symmetrically, giving rise to ABa and ABp, while the P1 daughter cell undergoes another asymmetric cell division to produce P2 and EMS. This division is also dependent on the distribution of the PAR proteins.
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Understanding the formation of a somatic embryo through establishment of morphological and molecular markers is important for construction of a fate map. The fate map is the foundation in which to build further research and experimentation. Two methods exist to construct a fate map: synchronous cell-division and time-lapse tracking. The latter typically works more consistently because of cell-cycle-altering chemicals and centrifuging involved in synchronous cell-division.
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Segrosomes are protein complexes that ensure accurate segregation (partitioning) of plasmids or chromosomes during bacterial cell division. Just as higher forms of life have evolved a complex mitotic apparatus to partition duplicated DNA during cell division, bacteria require a specialized apparatus to partition their duplicated DNA. In bacteria, segrosomes perform the function similar to that performed by mitotic spindle. Therefore, segrosomes can be thought of as minimalist spindles.
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The recognition of viral DNA is an important part of immune responses. For this virus to persist, the circular genome must be replicated and inherited during cell division.
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Also in contrast to the bifacial cambium, the unifacial cambium is unable to expand its circumference with anticlinal cell division. Cell elongation provides a limited amount of expansion.
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In addition, each daughter cell will contain half the number of the newly formed strips and half the number of the old strips present prior to cell division.
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When RCC-1 is not methylated, cell division is abnormal following the formation of extra spindle poles. The function of Retinoblastoma protein N-terminal methylation is not known.
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This surveillance mechanism assures correct segregation of chromosomes during cell division by detecting unaligned chromosomes and causing prometaphase arrest until the proper bipolar attachment of chromosomes is achieved.
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Thus the suppression of microtubule dynamics was described to be the main cause of the inhibition of cell division and of tumor cell death in paclitaxel treated cells.
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Lutkenhaus discovered, among other things, that the FtsZ protein forms a ring around the division plane in bacteria and is thus a key factor in bacterial cell division.
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Quadriviruses are transmitted internally. They are propagated during cell division and hyphal anastomosis. Viral replication occurs in the cytoplasm. It follows the double-stranded RNA virus replication model.
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Cell division, growth & proliferation Cell growth refers to an increase in the total mass of a cell, including both cytoplasmic, nuclear and organelle volume. Cell growth occurs when the overall rate of cellular biosynthesis (production of biomolecules or anabolism) is greater than the overall rate of cellular degradation (the destruction of biomolecules via the proteasome, lysosome or autophagy, or catabolism). Cell growth is not to be confused with cell division or the cell cycle, which are distinct processes that can occur alongside cell growth during the process of cell proliferation, where a cell, known as the "mother cell", grows and divides to produce two "daughter cells". Importantly, cell growth and cell division can also occur independently of one another.
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Hence, two cells grow (accumulate mass) at twice the rate of a single cell, and four cells grow at 4-times the rate of a single cell. This principle leads to an exponential increase of tissue growth rate (mass accumulation) during cell proliferation, owing to the exponential increase in cell number. Cell size depends on both cell growth and cell division, with a disproportionate increase in the rate of cell growth leading to production of larger cells and a disproportionate increase in the rate of cell division leading to production of many smaller cells. Cell proliferation typically involves balanced cell growth and cell division rates that maintain a roughly constant cell size in the exponentially proliferating population of cells.
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Nimotuzumab (h-R3, BIOMAb EGFR, Biocon, India;BIOMAb EGFR (Biocon, India) TheraCIM, CIMYM Biosciences, Canada; Theraloc, Oncoscience, Europe, CIMAher, Center of Molecular Immunology, Havana, Cuba) is a humanized monoclonal antibody that as of 2014 had orphan status in the US and EU for glioma, and marketing approval in India, China, and other countries for squamous cell carcinomas of the head and neck, and was undergoing several clinical trials. Like cetuximab, nimotuzumab binds to the epidermal growth factor receptor (EGFR), a signalling protein that normally controls cell division. In some cancers, this receptor is altered to cause uncontrolled cell division, a hallmark of cancer. These monoclonal antibodies block EGFR and stop the uncontrolled cell division.
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Pyrimethanil is a broad spectrum fungicide often applied to seeds. It inhibits methionine biosynthesis, thus affecting protein formation and subsequent cell division. Pyrimethanil works best on young fungus infestations.
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The PCM1 protein exhibits a distinct cell cycle-dependent association with the centrosome complex and microtubules; it is critical for the normal cell cycle and cell division (see PCM1).
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The protein contains a putative src homology 2 (SH2) domain, a hallmark of cellular tyrosine kinase signaling molecules, and is partly homologous to the cell division cycle protein CDC48.
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"Eicosapentaenoic acid plays a beneficial role in membrane organization and cell division of a cold-adapted bacterium, Shewanella livingstonensis Ac10." Journal of Bacteriology 191(2) (2009): 632–40. Print.
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In order to contract Roberts syndrome, a child must inherit the defective gene in an autosomal recessive manner. In other words, the child must inherit two copies of the defective gene (one from each parent). The ESCO2 gene has a specific effect on cell division in Roberts syndrome patients. In normal cell division, each chromosome is copied and then attached to its newly formed copy at the centromere (the center portion of a chromosome).
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DNA replication in bacteria is tightly linked to cell division. For instance, blocking replication in B. subtilis results in elongated cells without proper cell division. Bacterial DNA replication is initiated by the binding of DnaA (an ATPase) to the origin of replication (oriC) at midcell. FtsZ assembly appears to be linked to successful DNA replication with MatP and ZapB somehow coordinating interactions between the division machinery and DNA replication during chromosome segregation in E. coli.
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Organ growth relies on several processes occurring at the cellular level, including cell division and programmed cell death (or apoptosis). The Hippo signaling pathway is involved in restraining cell proliferation and promoting apoptosis. As many cancers are marked by unchecked cell division, this signaling pathway has become increasingly significant in the study of human cancer. Hippo pathway also has critical role in stem cell and tissue specific progenitor cell self-renewal and expansion.
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First, it reproduces both by cell division (splitting one cell into two) and by conjugation, in which two organisms temporarily join in order to swap DNA. Second, it has two cell nuclei. The larger, called the "macronucleus", carries out the normal work of the cell by transcribing DNA into RNA, which is used to control the cell's functions. The smaller "micronucleus" is used only for reproducing the organism by cell division and by conjugation.
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The first suggestion that loss of asymmetric cell division might be involved in tumorigenesis came from studies of Drosophila. Studies of loss-of-function mutations in key regulators of asymmetric cell division including lgl, aurA, polo, numb and brat, revealed hyperproliferative phenotypes in situ. In these mutants cells divide more symmetrically and generate mis-specified progeny that fail to exit the cell cycle and differentiate, but rather proliferate continuously and form a tumor cell mass.
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In addition to the mechanism described above, some antibiotics induce filamentation via the SOS response. During repair of DNA damage, the SOS response aids bacterial propagation by inhibiting cell division. DNA damage induces the SOS response in E.coli through the DpiBA two-component signal transduction system, leading to inactivation of the ftsl gene product, penicillin binding protein 3 (PBP-3). The ftsl gene is a group of filamentous temperature-sensitive genes implicated in cell division.
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There are some asymbiotic (occurs without an endosymbiont) Rhizosolenia, however there appears to be mechanisms limiting growth of these organisms in low nutrient conditions. Cell division for both the diatom host and cyanobacterial symbiont can be uncoupled and mechanisms for passing bacterial symbionts to daughter cells during cell division are still relatively unknown. Other endosymbiosis with nitrogen fixers in open oceans include Calothrix in Chaetocerous spp. and UNCY-A in prymnesiophyte microalga.
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Cyclin B plays in integral role in many types of cancer. Hyperplasia (uncontrolled cell growth) is one of the hallmarks of cancer. Because cyclin B is necessary for cells to enter mitosis and therefore necessary for cell division, cyclin B levels are often de-regulated in tumors. When cyclin B levels are elevated, cells can enter M phase prematurely and strict control over cell division is lost, which is a favorable condition for cancer development.
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On the other hand, if cyclin B levels are depleted the cyclin B/CDK1 complex cannot form, cells cannot enter M phase and cell division slows down. Some anti-cancer therapies have been designed to prevent cyclin B/CDK1 complex formation in cancer cells to slow or prevent cell division. Most of these methods have targeted the CDK1 subunit, but there is an emerging interest in the oncology field to target cyclin B as well.
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Homologous chromosomes are separated in the first division, and sister chromatids are separated in the second division. Both of these cell division cycles are used in the process of sexual reproduction at some point in their life cycle. Both are believed to be present in the last eukaryotic common ancestor. Prokaryotes (bacteria and archaea) usually undergo a vegetative cell division known as binary fission, where their genetic material is segregated equally into two daughter cells.
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The four phases of the cell cycle. G1 – the initial growth phase. S – the phase in which DNA is synthesised. G2 – the second growth phase in preparation for cell division.
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Several mechanisms, including oriented cell division, cell-cell intercalation and chemotactic cell movement, have been proposed to explain the nature of the cellular movements required to form the primitive streak.
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The cycle then repeats itself. The fungus infects the ovaries causing a pseudo-pollination and an enhanced cell division, resulting in the infested fruit being larger than the healthy one.
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Control of cell shape, cell division and cell-cell interaction are likely to be important in inhibiting cell proliferation and thus allocating resources to cell survival during periods of stress.
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Cinoxacin mode of action involves the inhibiting of DNA gyrase, a type II topoisomerase, and topoisomerase iv, which is an enzyme necessary to separate replicated DNA, thereby inhibiting cell division.
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FHAD1 contains one Smc (Structural maintenance of chromosomes) region from 275 - 1401 aa. This region encodes Smc proteins that are involved in cell cycle control, cell division and chromosome separation.
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M-phase inducer phosphatase 1 also known as dual specificity phosphatase Cdc25A is a protein that in humans is encoded by the cell division cycle 25 homolog A (CDC25A) gene.
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The Michael Swann Building of the University of Edinburgh at Kings Buildings is named after him. It continues to be used for work on cell division and fertilisation to this day.
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Cell division protein kinase 5 is an enzyme that in humans is encoded by the CDK5 gene. The protein encoded by this gene is part of the cyclin-dependent kinase family.
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The selectivities of these channels may be relatively weak in comparison to voltage-gated channels. In addition, some MscS channels may function in amino acid efflux, Ca2+ regulation and cell division.
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Cell division cycle 73, Paf1/RNA polymerase II complex component, homolog (S. cerevisiae), also known as CDC73 and parafibromin, is a protein which in humans is encoded by the CDC73 gene.
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Goodwin's model and its extensions have been widely used over the years as the basic skeleton for other models of oscillatory behavior, including circadian clocks, cell division or physiological control systems.
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Physical features may include short stature, large, low-set ears, a small jaw, a large mouth, epicanthic folds or fine, sparse hair. The syndrome is caused by mutations in both copies of the CENPF gene, which codes for centromere protein F. This protein is involved in cell division, in which it forms part of a disc-shaped protein complex known as a kinetochore. CENPF also has a role in orienting long, cylindrical structures called microtubules to form thin cell protrusions called cilia, which send and receive signals to trigger cell division, migration or differentiation. Mutations in the gene result in slower cell division and some embryonic developmental processes being disrupted or not completed, and the syndrome can be classified as a ciliopathy.
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Thus, cell proliferation is not synonymous with either cell growth or cell division, despite the fact that these terms are sometimes used interchangeably. Stem cells undergo cell proliferation to produce proliferating "transit amplifying" daughter cells that later differentiate to construct tissues during normal development and tissue growth, during tissue regeneration after damage, or in cancer. The total number of cells in a population is determined by the rate of cell proliferation minus the rate of cell death. Cell size depends on both cell growth and cell division, with a disproportionate increase in the rate of cell growth leading to production of larger cells and a disproportionate increase in the rate of cell division leading to production of many smaller cells.
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An excess of centrosomes can be generated by very different mechanisms: specific reduplication of the centrosome, cytokinesis failure during cell division (generating an increase in chromosome number), cell fusion (for instance due to infection by specific viruses) or de novo generation of centrosomes. At this point there is not sufficient information to know how frequent those mechanisms are in vivo, but it is possible that the increase in centrosome numbers due to a failure during cell division might be more frequent than appreciated, because many "primary" defects in one cell (deregulation of the cell cycle, defective DNA or chromatin metabolism, failure in the spindle checkpoint, etc...) would generate a failure in cell division, an increase in ploidy and an increase in centrosome numbers as a "secondary" effect.
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Thymidine kinase is a salvage enzyme that is only present in anticipation of cell division. The enzyme is not set free from cells undergoing normal division where the cells have a special mechanism to degrade the proteins no longer needed after the cell division. In normal subjects, the amount of thymidine kinase in serum or plasma is therefore very low. Tumor cells release enzyme to the circulation, probably in connection with the disruption of dead or dying tumor cells.
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On the cellular level, auxin is essential for cell growth, affecting both cell division and cellular expansion. Auxin concentration level, together with other local factors, contributes to cell differentiation and specification of the cell fate. Depending on the specific tissue, auxin may promote axial elongation (as in shoots), lateral expansion (as in root swelling), or iso-diametric expansion (as in fruit growth). In some cases (coleoptile growth), auxin-promoted cellular expansion occurs in the absence of cell division.
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Hamartin and tuberin function as a complex which is involved in the control of cell growth and cell division. The complex appears to interact with RHEB GTPase, thus sequestering it from activating mTOR signalling, part of the growth factor (insulin) signalling pathway. Thus, mutations at the TSC1 and TSC2 loci result in a loss of control of cell growth and cell division, and therefore a predisposition to forming tumors. TSC affects tissues from different germ layers.
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Salvage enzymes are enzymes, nucleoside kinases, required during cell division to "salvage" nucleotides, present in body fluids, for the manufacture of DNA. They catalyze the phosphorylation of nucleosides to nucleoside - 5'-phosphates, that are further phosphorylated to triphosphates, that can be built into the growing DNA chain. The salvage enzymes are synthesized during the G1 phase in anticipation of DNA synthesis. After the cell division has been completed, the salvage enzymes, no longer required, are degraded.
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ADEP activation of ClpP does not allow for folded protein degradation, but even with unfolded protein and peptide degradation, ADEP still causes bacterial cell death. Research has shown that ADEP-activated ClpP targets cell division rather than metabolic processes. ADEP appears to initiate ClpP to preferably degrade FtsZ, an important bacterial protein involved in septum formation that is necessary for bacterial cell division. As a result, Gram-positive bacteria treated with ADEPs form long filaments before cell death.
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G proteins without hydrolytic activity cannot hydrolyze bound GTP. GAPs cannot activate a nonfunctional enzyme, and the G protein is constitutively active, resulting in unregulated cell division and the formation of tumors.
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The paper documenting this work is one of the Nature Milestones in Cell Division. Li has subsequently made a number of significant discoveries in the area of mitotic exit control and cytokinesis.
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Myosin VIII is a plant-specific myosin linked to cell division; specifically, it is involved in regulating the flow of cytoplasm between cells and in the localization of vesicles to the phragmoplast.
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After cell division, the daughter cells leave the cyst envelope leaving behind food remnants. During unfavourable conditions the cell may enter into a resting phase. Sex is currently unknown in the genus.
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150 Years of cell division. Dermatopathology: Practical & Conceptual, Vol. 8, No. 2. link. The term "mesoderm" was introduced into English by Huxley in 1871, and "ectoderm" and "endoderm" by Lankester in 1873.
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Although there are differences between animal, plant, and microbial cells, the basic physiological functions of cells can be divided into the processes of cell division, cell signaling, cell growth, and cell metabolism.
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Cell division. All cells can be considered motile for having the ability to divide into two new daughter cells. Motility is the ability of an organism to move independently, using metabolic energy.
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Moreover, RalA specifically interacts with Exo84 and Sec5 to regulate transport of membrane proteins in polarized epithelial cells and GLUT4 to the plasma membrane, as well as mitochondrial fission for cell division.
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In the amoeba, reproduction occurs by cell division of the parent cell: first the nucleus of the parent divides into two and then the cell membrane also cleaves, becoming two "daughter" Amoebae.
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Each trastuzumab molecule may be linked to zero to eight DM1 molecules (3.5 on average). DM1 binds at plus ends of cellular microtubules and thereby inhibits cell division in the target tumor cells.
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However, the granules were later determined to not participate in the cell division. The colored grains are composed of volutin, whereas the colorless inclusions are drops of fat, which act as energy reserves.
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One alternative to the omnigenic hypothesis is the idea that peripheral genes act not by altering core genes but by altering cellular states, such as the speed of cell division or hormone response.
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Some consider him to be the true discoverer of cell division, although he is rarely credited as such.Amos, B. (2000). Lessons from the history of light microscopy. Nature Cell Biology, 2: E151-E152.
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Vegetative segregation, the random partitioning of cytoplasm, is a distinguishable characteristic of organelle heredity. During cell division, the organelles are divided equally, providing each daughter cell with a random selection of plasmid genotypes.
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McClung, C. E. (1913). Reviewed Work: Problems of Life and Reproduction by Marcus Hartog. Science 38 (984): 666-668. He argued that cell division occurs due to a new force he termed "mitokinetism".
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Activated ERKs are pleiotropic effectors of cell physiology and play an important role in the control of gene expression involved in the cell division cycle, cell migration, inhibition of apoptosis, and cell differentiation.
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Function of the primary cilium is impaired, resulting in disruption of a number of intracellular signaling cascades which produce differentiation of cystic epithelium, increased cell division, increased apoptosis, and loss of resorptive capacity.
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In symmetric cell division, both daughter cells are also stem cells. In asymmetric division, a stem cell produces one stem cell and one specialized cell. NSCs primarily differentiate into neurons, astrocytes, and oligodendrocytes.
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These connections are formed when an unequal cell division produced a nucleated daughter cell that then fuses to an adjacent cell. Patterns of secondary pit connections can be seen in the order Ceramiales.
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The presence of the SPA domain within LCHN suggests that it may play a role in cell division. LCHN has been shown to physically associate with EFNB3, a protein with reported importance in neuronal development. A second reported association with SETBP1 may open up the possibility for LCHN to play a role in cell cycle regulation from within the nucleus. The predicted KIAA1147 promoter contains binding sites for cell-division related factors and factors known to have specific expression during neuronal development.
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However, when there is no lysine supplied, genes encoding enzymes for lysine biosynthesis become essential, as no protein synthesis is possible without lysine. Streptococcus pneumoniae appears to require 147 genes for growth and survival in saliva, more than the 113-133 that have been found in previous studies. The deletion of a gene may result in death or in a block of cell division. While the latter case may implicate "survival" for some time, without cell division the cell may still die eventually.
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Altered JAK-STAT signalling can also be involved in developing breast cancer. JAK-STAT signalling in mammary glands (located within breasts) can promote cell division and reduce cell apoptosis during pregnancy and puberty, and therefore if excessively activated, cancer can form. High STAT3 activity plays a major role in this process, as it can allow the transcription of genes such as BCL2 and c-Myc, which are involved in cell division. Mutations in JAK2 can lead to leukaemia and lymphoma.
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Prior to cell division, the DNA material in the original cell must be duplicated so that after cell division, each new cell contains the full amount of DNA material. The process of DNA duplication is usually called replication. The replication is termed semiconservative since each new cell contains one strand of original DNA and one newly synthesized strand of DNA. The original polynucleotide strand of DNA serves as a template to guide the synthesis of the new complementary polynucleotide of DNA.
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His were neuronal stem cells, their asymmetrical cell division and processes of growth control. Building on his post-doctoral work, Knoblich and his colleagues characterized a complete mechanism for asymmetrical stem cell division in neural stem cells of the fruitfly Drosophila. Their results were published in a series of seminal papers, including a report in Cell in 2008. Until then, it was unknown how stem cells can separate into a self- renewing daughter cell and a specialized differentiating cell at the same time.
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Thus, an infant's immune system is not highly activated and the infant produces fewer antibodies. Even when B cells do bind to the pathogen, immune response is still frequently repressed. If B cell receptors bind to the antigen and FC receptors simultaneously bind to the maternal antibody, the FC receptors send a signal to B cell receptors that inhibits cell division. Because the infant's immune system is not stimulated and B cell division is inhibited, few memory B cells are produced.
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Most bony fish eggs are referred to as telolecithal which means that most of the egg cell cytoplasm is yolk. The yolky end of the egg (the vegetal pole) remains homogenous while the other end (the animal pole) undergoes cell division. Cleavage, or initial cell division, can only occur in a region called the blastodisc, a yolk free region located at the animal pole of the egg. The fish zygote is meroblastic, meaning the early cell divisions are not complete.
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DNA replication occurs during the C period. The D period refers to the stage between the end of DNA replication and the splitting of the bacterial cell into two daughter cells. The cell-division cycle is a vital process by which a single-celled fertilized egg develops into a mature organism, as well as the process by which hair, skin, blood cells, and some internal organs are renewed. After cell division, each of the daughter cells begin the interphase of a new cycle.
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The cell division cycle protein 20 homolog is an essential regulator of cell division that is encoded by the CDC20 gene in humans. To the best of current knowledge its most important function is to activate the anaphase promoting complex (APC/C), a large 11-13 subunit complex that initiates chromatid separation and entrance into anaphase. The APC/CCdc20 protein complex has two main downstream targets. Firstly, it targets securin for destruction, enabling the eventual destruction of cohesin and thus sister chromatid separation.
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Serum folate reacts more rapidly to folate intake than erythrocyte folate. Since folate deficiency limits cell division, erythropoiesis (production of red blood cells) is hindered. This leads to megaloblastic anemia, which is characterized by large, immature red blood cells. This pathology results from persistently thwarted attempts at normal DNA replication, DNA repair, and cell division, and produces abnormally large red cells called megaloblasts (and hypersegmented neutrophils) with abundant cytoplasm capable of RNA and protein synthesis, but with clumping and fragmentation of nuclear chromatin.
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While binary fission may be the means of division by most prokaryotes, there are alternative manners of division, such as budding, that have been observed. All cell divisions, regardless of organism, are preceded by a single round of DNA replication. For simple unicellular microorganisms such as the amoeba, one cell division is equivalent to reproduction – an entire new organism is created. On a larger scale, mitotic cell division can create progeny from multicellular organisms, such as plants that grow from cuttings.
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The growth of the cell plate eventually disrupts the telophase spindle (see case 4 in picture). In the Chlorophyceae, the most common form of cell division occurs via a phycoplast. In these algae, the spindle collapses and a new system of microtubules forms that is oriented in parallel to the plane of cell division. This phycoplast can be observed in algae undergoing cytokinesis via cleavage furrow (case 1 in picture) as well as algae utilizing a cell plate (case 3 in picture).
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Thymidine kinase is a salvage enzyme that is only present in anticipation of cell division. The enzyme is not set free from cells undergoing normal division where the cells have a special mechanism to degrade the proteins no longer needed after cell division is completed. In normal subjects, the amount of thymidine kinase in serum or plasma is, therefore, very low. Tumor cells release enzyme to the circulation, probably in connection with the disruption of dead or dying tumor cells.
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Another mutation in the same gene results in a nonfunctional inhibitor of CDK4, a cyclin-dependent kinase that promotes cell division. Mutations that cause the skin condition xeroderma pigmentosum (XP) also increase melanoma susceptibility.
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It disassembles during cell division and reforms in the daughter cells in an asymmetric fashion in relation to the cytoskeleton. This asymmetric positioning of the eyespot in the cell is essential for proper phototaxis.
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The phycoplast may play a role in assuring that the plane of cell division will pass between the two daughter nuclei. Typically, these algae undergo "closed" mitosis where the nuclear envelope persists throughout mitosis.
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It was originally believed to be a new green alga. However, it was discovered that the chlorophyll-bearing plastids were independent of the cell division, indicating that they were separate but temporary endosymbiotic organisms.
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Centrosomal protein of 55 kDa is a protein that in humans is encoded by the CEP55 gene. CEP55 is a mitotic phosphoprotein that plays a key role in cytokinesis, the final stage of cell division.
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MITO-FLAG (also called Mito-FLAG, FLAG-MITO, or FLAG-Mito) adds mitoxantrone to the standard regimen. Mitoxantrone is a synthetic anthracycline analogue (an anthracenedione) that, like idarubicin, can intercalate DNA and prevent cell division.
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Although the various stages of interphase are not usually morphologically distinguishable, each phase of the cell cycle has a distinct set of specialized biochemical processes that prepare the cell for initiation of the cell division.
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In biology, a blastomere is a type of cell produced by cleavage (cell division) of the zygote after fertilization and is an essential part of blastula formation.Blastomere Encyclopædia Britannica. Encyclopædia Britannica Online. Encyclopædia Britannica Inc.
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A complete absence of (p)ppGpp causes multiple amino acid requirements, poor survival of aged cultures, aberrant cell division, morphology, and immotility, as well as being locked in a growth mode during entry into starvation.
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Upon proper segregation, a complete set of chromatids ends up in each of two nuclei, and when cell division is completed, each DNA copy previously referred to as a chromatid is now called a chromosome.
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Successful cell division requires identification and correction of any dangerous errors before the cell splits in two. If the syntelic attachment continues, it causes both sister chromatids to be segregated to a single daughter cell.
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Cell division orientation is one of the mechanisms that shapes tissue during development and morphogenesis. Along with cell shape changes, cell rearrangements, apoptosis and growth, oriented cell division modifies the geometry and topology of live tissue in order to create new organs and shape the organisms. Reproducible patterns of oriented cell divisions were described during morphogenesis of Drosophila embryos, Arabidopsis thaliana embryos, Drosophila pupa, zebrafish embryos and mouse early embryos. Oriented cell divisions contribute to the tissue elongation and the release of mechanical stress.
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In liposomes Osawa (2009) showed FtsZ is capable of exerting a contractile force with no other proteins present. Erickson (2009) proposed how the roles of tubulin-like proteins and actin-like proteins in cell division became reversed in an evolutionary mystery. The use of the FtsZ ring in dividing chloroplasts and some mitochondria further establishes their prokaryotic ancestry. L-form bacteria that lack a cell wall do not require FtsZ for division, which implies that bacteria may have retained components of an ancestral mode of cell division.
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The result is a cell that divides more often. An example of this includes the translocation of C-MYC, a gene that encodes a transcription factor that leads to increased cell division, next to the immunoglobulin heavy- or light-chain gene enhancers, leading to increased C-MYC expression and increased cell division. Other large changes in chromosomal structure can result in placement of two genes directly next to each other. The result is the combination of two usually separate proteins into a new fusion protein.
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The ER activity can be monitored using immunohistochemical methods in applications like tissue analysis for tumorgenesis. The activation of the ER through binding to the estrogen hormone stimulates the mammary cell division, catalyzing the cell division and DNA replication process. This results in exponential multiplication of replications of the mutated genes, along with large amounts of genotoxic waste in response to this estrogen metabolism pathway. These ill effects highly increase the chances of malignant cell formation, and in turn, increases the chance of tumor formation.
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In mice, this gene has shown reduced expression in ageing animals causes cognitive long-term memory decline. In Dnmt3a-/- mice, many genes associated with HSC self-renewal increase in expression and some fail to be appropriately repressed during differentiation. This suggests abrogation of differentiation in hematopoietic stem cells (HSCs) and an increase in self-renewal cell-division instead. Indeed, it was found that differentiation was partially rescued if Dnmt3a-/- HSCs experienced an additional Ctnb1 knockdown – Ctnb1 codes for β-catenin, which participates in self-renewal cell division.
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FtsK is a 1329 amino acid protein involved in bacterial cell division and chromosome segregation. FtsK stands for " _F_ ilament _t_ emperature _s_ ensitive mutant K" because at high temperatures the mutant bacterial cell fails to divide and long filaments develop instead. FtsK, and specifically its C-domain, functions as DNA pump, interacts with other cell division proteins, and intervenes in the regulation of the Xer recombination process. FtsK belongs to the AAA (ATPase Associated with various cellular Activities) superfamily and is present in most bacteria.
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Vegetative cell division occurs over hundreds of generations for C. meneghiniana, with the cell diameters of the offspring organisms becoming gradually smaller. Regardless of the flexibility of the girdle bands and functionality of vegetative cell division, there is a point where the diameter of C. meneghiniana offspring dips below a certain threshold diameter. It has been observed that at this point, species-specific environmental stimuli induces the change from asexual reproduction to sexual reproduction. Sexual reproduction occurs with gametes being formed upon reaching the threshold.
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Although the specific mechanisms between mitochondria and the cell cycle regulation is not well understood, studies have shown that low energy cell cycle checkpoints monitor the energy capability before committing to another round of cell division.
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In the FLAG-IDA regimen (also called FLAG-Ida, IDA-FLAG, or Ida-FLAG), idarubicin—an anthracycline antibiotic that is able to intercalate DNA and prevent cell division (mitosis)—is added to the standard FLAG regimen.
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Cryptoglena reproduce asexually via binary fission. Prior to cell division, the nucleus undergoes mitosis. The ploidy of Cryptoglena has not been investigated (although it is likely haploid), and the life cycle has not been studied thoroughly.
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The protein also interacts with the tail of Myosin 1 proteins. In fission yeast, Bbc1 is considered a WIP family cytoskeletal protein. Bbc1 localizes to actin cortical patches, cell division sites, the cell tip, and the cytosol.
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During cell division, severing at the spindle pole produces free microtubule ends and allows poleward flux of tubulin and retraction of the microtubule. Severing microtubules in the cytoplasm facilitates treadmilling and mobility, which is important during development.
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The tumor often displays characteristic chromosomal translocations between chromosomes #3 and #8. This causes the PLAG gene to be juxtaposed to the gene for beta catenin. This activates the catenin pathway and leads to inappropriate cell division.
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Overview of the steps in DNA replication DNA replication, and the various enzymes involved In nature, DNA molecules are synthesised by all living cells through the process of DNA replication. This typically occurs as a part of cell division. DNA replication occurs so, during cell division, each daughter cell contains an accurate copy of the genetic material of the cell. In vivo DNA synthesis (DNA replication) is dependent on a complex set of enzymes which have evolved to act during the S phase of the cell cycle, in a concerted fashion.
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As chemotherapy affects cell division, tumors with high growth rates (such as acute myelogenous leukemia and the aggressive lymphomas, including Hodgkin's disease) are more sensitive to chemotherapy, as a larger proportion of the targeted cells are undergoing cell division at any time. Malignancies with slower growth rates, such as indolent lymphomas, tend to respond to chemotherapy much more modestly. Heterogeneic tumours may also display varying sensitivities to chemotherapy agents, depending on the subclonal populations within the tumor. Cells from the immune system also make crucial contributions to the antitumor effects of chemotherapy.
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These use electrons from the oxidation of ammonia to produce energy. It obtains the carbon it requires from the atmosphere via carbon fixation, which converts gaseous carbon dioxide into carbon bound in organic molecules. Unlike plants, which fix carbon into sugars through energy gained through the process of photosynthesis, Nitrosomonas use energy gained through the oxidation of ammonia to fix gaseous carbon dioxide into organic molecules. Nitrosomonas must consume large amounts of ammonia before cell division can occur, and the process of cell division may take up to several days.
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Flemming investigated the process of cell division and the distribution of chromosomes to the daughter nuclei, a process he called mitosis from the Greek word for thread. However, he did not see the splitting into identical halves, the daughter chromatids. He studied mitosis both in vivo and in stained preparations, using as the source of biological material the fins and gills of salamanders. These results were published first in 1878 and in 1882 in the seminal book Zellsubstanz, Kern und Zelltheilung (1882; Cell substance, nucleus and cell division).
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The final part of the cell reproduction process is cell division, when daughter cells physically split apart from a parental cell. During meiosis, there are two cell division steps that together produce the four daughter cells. After the completion of binary fission or cell reproduction involving mitosis, each daughter cell has the same amount of DNA (Z) as what the parental cell had before it replicated its DNA. These two types of cell reproduction produced two daughter cells that have the same number of chromosomes as the parental cell.
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This type of meroblastic cleavage is called discoidal because only the blastodisc becomes the embryo. In fish, waves of calcium released direct the process of cell division by coordinating the mitotic apparatus with the actin cytoskeleton, propagating cell division along the surface, assists in deepening the cleavage furrow, and finally heals the membrane after separation of blastomeres. The fate of the first cells, called blastomeres, is determined by its location. This contrasts with the situation in some other animals, such as mammals, in which each blastomere can develop into any part of the organism.
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Liposome formulations that encapsulate anti-cancer drugs for selective uptake to tumors via the EPR effect include: Doxil and Myocet, both of which encapsulate doxorubicin (a DNA intercalator and common chemotherapeutic); DaunoXome, which encapsulates daunorubicin (a similar DNA intercalator); and Onco-TCS, which encapsulates vincristine (a molecule that induces formation of microtubules, dysregulating cell division). Another novel utilization of the EPR effect comes from Protein-bound paclitaxel (marketed under the trade name Abraxane) where paclitaxel (a molecule which dysregulates cell division via stabilization of microtubules) is bound to albumin to add bulk and aid delivery.
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At each end of the chromosomes of most eukaryotic cells, there is a telomere: a region of repetitive nucleotide sequences which protects the end of the chromosome from deterioration or from fusion with neighboring chromosomes. At each cell division, the telomeres get shorter, eventually preventing further cell division. Healthy adult somatic cells in mammals do not have active telomerase enzymes, so that cancer cells stop proliferating unless they have a mutation which restores the telomeres. Often, this is due to a telomerase enyme being reactivated, but alternative mechanisms also occur.
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Asymmetric cell divisions during the first steps of the embryogenesis of C. elegans In C. elegans, a series of asymmetric cell divisions in the early embryo are critical in setting up the anterior/posterior, dorsal/ventral, and left/right axes of the body plan.Gönczy, P. and Rose, L.S. Asymmetric cell division and axis formation in the embryo (October 15, 2005), WormBook, ed. The C. elegans Research Community, WormBook, doi/10.1895/wormbook.1.30.1, After fertilization, events are already occurring in the zygote to allow for the first asymmetric cell division.
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Life cycle of the cell Onion (Allium) cells in different phases of the cell cycle. Growth in an 'organism' is carefully controlled by regulating the cell cycle. Cell cycle in Deinococcus radiodurans The cell cycle, or cell-division cycle, is the series of events that take place in a cell that cause it to divide into two daughter cells. These events include the duplication of its DNA (DNA replication) and some of its organelles, and subsequently the partitioning of its cytoplasm and other components into two daughter cells in a process called cell division.
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Volasertib is a novel small-molecule targeted therapy that blocks cell division by competitively binding to the ATP-binding pocket of the PLK1 protein. PLK1 proteins are found in the nuclei of all dividing cells and control multiple stages of the cell cycle and cell division. The levels of the PLK1 protein are tightly controlled and are raised in normal cells that are dividing. Raised levels of the PLK1 protein are also found in many cancers including; breast, non-small cell lung, colorectal, prostate, pancreatic, papillary thyroid, ovarian, head and neck and Non-Hodgkin’s Lymphoma.
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A spindle poison, also known as a spindle toxin, is a poison that disrupts cell division by affecting the protein threads that connect the centromere regions of chromosomes, known as spindles. Spindle poisons effectively cease the production of new cells by interrupting the mitosis phase of cell division at the spindle assembly checkpoint (SAC). However, as numerous and varied as they are, spindle poisons are not yet 100% effective at ending the formation of tumors (neoplasms).Wood KW, Cornwell WD, Jackson JR. (2001) Past and future of the mitotic spindle as an oncology target.
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Gram-negative bacteria harbor genes encoding for molecular pumps which can contribute to resistance of hydrophobic compounds like macrolides and lincosamides. Out of the many families of multidrug resistance pumps, lincosamides are most commonly shunted through pumps belonging to the resistance-nodulation-cell division superfamily. Staphylococci express efflux pumps with specificity for 14 and 15 member ring macrolides and streptogramin B, but not lincosamide molecules. Example of drug efflux through a pump belonging to the resistance-nodulation-cell division superfamily, the type of pump primarily responsible for lincosamide efflux.
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Iain Cheeseman investigates the role of the kinetochore, a group of proteins required for cell division and chromosome segregation. This core network of proteins facilitates the attachment of chromosomes to microtubule polymers—the spindle structures that attach to the ends of cells, pulling and dividing them during cell division. The kinetochore is critical to ensuring duplication without loss or damage to the genetic material. Cheeseman is also investigating the activities of the individual molecular machines that make up this structure and how these proteins are controlled and regulated.
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The resulting daughter cells of the first cell division are called the AB cell (containing PAR-6 and PAR-3) and the P1 cell (containing PAR-1 and PAR-2). A second cell division produces the ABp and ABa cells from the AB cell, and the EMS and P2 cells from the P1 cell. This division establishes the dorsal-ventral axis, with the ABp cell forming the dorsal side and the EMS cell marking the ventral side. Through Wnt signaling, the P2 cell instructs the EMS cell to divide along the anterior-posterior axis.
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One of the first studies of cell lineages took place in the 1870s by Whitman who studied cleavage patterns in leeches and small invertebrates. He found that some groups, such as nematode worms and ascidians form a pattern of cell division which is identical between individuals and invariable. This high correlation between cell lineage and cell fate was thought to be determined by segregating factors within the dividing cells. Other organisms had stereotyped patterns of cell division and produced sublineages which were the progeny of particular precursor cells.
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Flagella are only present in the motile male gametes of charophytes bryophytes, pteridophytes, cycads and Ginkgo, but are absent from the gametes of Pinophyta and flowering plants. Members of the class Chlorophyceae undergo closed mitosis in the most common form of cell division among the green algae, which occurs via a phycoplast. By contrast, charophyte green algae and land plants (embryophytes) undergo open mitosis without centrioles. Instead, a 'raft' of microtubules, the phragmoplast, is formed from the mitotic spindle and cell division involves the use of this phragmoplast in the production of a cell plate.
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G1 phase together with the S phase and G2 phase comprise the long growth period of the cell cycle cell division called interphase that takes place before cell division in mitosis (M phase). During G1 phase, the cell grows in size and synthesizes mRNA and protien that are required for DNA synthesis. Once the required proteins and growth are complete, the cell enters the next phase of the cell cycle, S phase. The duration of each phase, including the G1 phase, is different in many different types of cells.
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During cell division, the molecules that compose chromosomes (DNA and proteins) suffer a condensation process (called the chromatin condensation) that forms a compact and small complex called a chromatid. The complexes containing the duplicated DNA molecules, the sister chromatids, are attached to each other by the centromere(where the Kinetochore assembles). The centromere divides each chromosome into two regions: the smaller one, which is the p region, and the bigger one, the q region. The sister chromatids will be distributed to each daughter cell at the end of the cell division.
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Brassinolide is a plant hormone. The first isolated brassinosteroid, it was discovered when it was shown that pollen from rapeseed (Brassica napus) could promote stem elongation and cell division. The biologically active component was isolated and named brassinolide.
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Most eukaryotic cell types usually have a single nucleus, but some have no nuclei, while others have several. This can result from normal development, as in the maturation of mammalian red blood cells, or from faulty cell division.
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Stevenson, A., Hamill, P. G., O'kane, C. J., Kminek, G., Rummel, J. D., Voytek, M. A., Dijksterhuis, J., and Hallsworth, J. E. "Aspergillus penicillioides differentiation and cell division at 0.585 water activity." Environmental Microbiology 19.2 (2017):687-697.
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The "bubble" alga is attached by rhizoids to the substrate fibers. Reproduction occurs by segregative cell division, where the multinucleate parent cell makes child cells, and individual rhizoids form new bubbles, which become separate from the parent cell.
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Topoisomerase III from the IA family is used for cell growth. Without topoisomerase III, recombination rates in mitosis and meiosis can increase, which slows growth in cells. In S. pombe cells, III is used to sustain cell division.
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Drp1 has been linked to a number of pathways and processes including cell division, apoptosis, and necrosis. Drp1 has been shown to stabilize p53 during oxidative stress, promoting its translocation to the mitochondria and encouraging mitochondrial- related necrosis.
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Centromere protein F is a protein that in humans is encoded by the CENPF gene. It is involved in chromosome segregation during cell division. It also has a role in the orientation of microtubules to form cellular cilia.
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Complex of α, β tubulin subunits and paclitaxel. Paclitaxel is shown as yellow stick. Paclitaxel is one of several cytoskeletal drugs that target tubulin. Paclitaxel-treated cells have defects in mitotic spindle assembly, chromosome segregation, and cell division.
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Translation takes place by -1 ribosomal frameshifting. The virus exits the host cell by cell-to-cell movement. Fungi Saccharomyces cerevisiae and smut serve as the natural host. The virus is transmitted during cell division, sporogenesis, and cell fusion.
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These kinases consist of a transmembrane receptor with a tyrosine kinase domain protruding into the cytoplasm. They play an important role in regulating cell division, cellular differentiation, and morphogenesis. More than 50 receptor tyrosine kinases are known in mammals.
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Zinc pyrithione (or pyrithione zinc) is a coordination complex of zinc. It has fungistatic (that is, it inhibits the division of fungal cells) and bacteriostatic (inhibits bacterial cell division) properties and is used in the treatment of seborrhoeic dermatitis.
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Unregulated cell division can lead to the formation of a tumor (see cancer), which is potentially lethal to an organism. Therefore, the induction of senescence and apoptosis is considered to be part of a strategy of protection against cancer.
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The mitochondrial genome of the Trypanosoma, as well as of other kinetoplastids, known as the kinetoplast, is made up of a highly complex series of catenated circles and minicircles and requires a cohort of proteins for organisation during cell division.
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It maintains the viral genomes during cell division by tethering the viral episomes to the chromosomes. It binds directly to replication origin recognition complexes (ORCs) that are primarily associated with the terminal repeat (TR) region of the HHV-8 genome.
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Dev Dyn 2009, 238:789-796. Segalen M, Bellaiche Y: Cell division orientation and planar cell polarity pathways. Semin Cell Dev Biol 2009, 20:972-977. Fazi F, Nervi C: MicroRNA: basic mechanisms and transcriptional regulatory networks for cell fate determination.
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The BCR-ABL1 fusion gene and protein encoded by the Philadelphia chromosome affects multiple signaling pathways that directly affect apoptotic potential, cell division rates, and different stages of the cell cycle to achieve unchecked proliferation characteristic of CML and ALL.
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XL-413 is a drug which acts as a selective inhibitor of the enzyme cell division cycle 7-related protein kinase (CDC7). It is being researched for the treatment of some forms of cancer, and also has applications in genetic engineering.
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In a series of experiments from 1970 to 1971, Hartwell discovered the cell division cycle (CDC) genes in baker's yeast (Saccharomyces cerevisiae). These genes regulate the cell cycle and mutations in the genes are involved in some types of cancer.
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Little documentation of the Corallochytrium life cycle exists. However it is known that Corallochytrium produces colonies by binary, palintomic cell division (Raghu-kumar, 1987). Completion of the Corallochytrium life cycle involves the release of limax- shaped spores (Raghu-kumar, 1987).
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Loracarbef, a carbacephem Carbacephems are a class of synthetic antibiotics, based on the structure of cephalosporin, a cephem. Carbacephems are similar to cephems, but with a carbon substituted for the sulfur. It prevents bacterial cell division by inhibiting cell wall synthesis.
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In comparing them, strains SM124 and SM127, hypermotile derivatives of strains SM101 and SM102, respectively, contained 10 and six nucleotide polymorphisms (SNPs) relative to their parent strains. Mutations in cell division genes is the common feature of the hypermotile strains.
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Both sets of chromosomes, now surrounded by new nuclear membrane, begin to "relax" or decondense. Mitosis is complete. Each daughter nucleus has an identical set of chromosomes. Cell division may or may not occur at this time depending on the organism.
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The nucleus typically lies in the posterior half of the cell. The mitochondria have tubular cristae. Organelles called dictyosomes are present and arranged in a horseshoe like shape. Members of this genus are known to reproduce asexually through cell division.
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Journal of Experimental sciences. 1 (2): 26. The provision of triacontanol rapidly increase the morphogenetic response in the plant during the embryogenesis process. The enhanced response lead to increase in the cell division and cell growth by the growth regulators.
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Other serious side effects include shortness of breath. Use during pregnancy may harm the baby. Vinorelbine is in the vinca alkaloid family of medications. It is believed to work by disrupting the normal function of microtubules and thereby stopping cell division.
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In 2006, molecular biologist Gary J. Gorbsky and his lab were the first to reverse the process of cell division, a discovery detailed in the journal Nature that may have implications for the prevention and treatment of cancer and birth defects.
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Cytostatics inhibit cell division. In immunotherapy, they are used in smaller doses than in the treatment of malignant diseases. They affect the proliferation of both T cells and B cells. Due to their highest effectiveness, purine analogs are most frequently administered.
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Septins have been implicated in the localization of cellular processes at the site of cell division, and at the cell membrane at sites where specialized structures like cilia or flagella are attached to the cell body. In yeast cells, they compartmentalize parts of the cell and build scaffolding to provide structural support during cell division at the septum, from which they derive their name. Research in human cells suggests that septins build cages around pathogenic bacteria, that immobilize and prevent them from invading other cells. As filament forming proteins, septins can be considered part of the cytoskeleton.
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Studies looking at cell division history found that the length of telomere and activity of telomerase were reduced in effector T cells comparing to memory T cells, which suggests that memory T cells did not undergo as much cell division as effector T cells, which is inconsistent with the On-Off-On model. Repeated or chronic antigenic stimulation of T cells, like HIV infection, would induce elevated effector functions but reduce memory. It was also found that massively proliferated T cells are more likely to generate short-lived effector cells, while minimally proliferated T cells would form more long-lived cells.
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Tyrosine kinase inhibitors (such as sunitinib, pazopanib, and dasatinib) have shown some effect against several cancer types, most notably Imatinib-mesylate in gastrointestinal stromal tumors (GISTs). Tyrosine kinase (a subclass of protein kinases) is an enzyme that transfers a phosphate group from an ATP molecule to a protein in a cell. It functions as an “on” or “off” switch for many cellular functions, including signaling within the cell, and cell division. Tyrosine kinases can contain mutations that cause them to become constitutively active, or stuck in the “on” position, resulting in unregulated cell division (a hallmark of cancer).
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The JAK- STAT pathway in cytokine receptor signalling can activate STATs, which can bind to DNA and allow the transcription of genes involved in immune cell division, survival, activation and recruitment. For example, STAT1 can enable the transcription of genes which inhibit cell division and stimulate inflammation. Also, STAT4 is able to activate NK cells (natural killer cells), and STAT5 can drive the formation of white blood cells. In response to cytokines, such as IL-4, JAK-STAT signalling is also able to stimulate STAT6, which can promote B-cell proliferation, immune cell survival, and the production of an antibody called IgE.
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Cell division is a physiological process that occurs in almost all tissues and under a variety of circumstances. Normally the balance between proliferation and programmed cell death, in the form of apoptosis, is maintained to ensure the integrity of tissues and organs. According to the prevailing accepted theory of carcinogenesis, the somatic mutation theory, mutations in DNA and epimutations that lead to cancer disrupt these orderly processes by disrupting the programming regulating the processes, upsetting the normal balance between proliferation and cell death. This results in uncontrolled cell division and the evolution of those cells by natural selection in the body.
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In normal stem and progenitor cells, asymmetric cell division balances proliferation and self-renewal with cell- cycle exit and differentiation. Disruption of asymmetric cell division leads to aberrant self-renewal and impairs differentiation, and could therefore constitute an early step in the tumorogenic transformation of stem and progenitor cells. In normal non-tumor stem cells, a number of genes have been described which are responsible for pluripotency, such as Bmi-1, Wnt and Notch. These genes have been discovered also in the case of cancer stem cells, and shows that their aberrant expression is essential for the formation of tumor cell mass.
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In prokaryotes (bacteria and archaea) this usually occurs via a relatively simple process called binary fission, in which each circular genome attaches to the cell membrane and is separated into the daughter cells as the membrane invaginates to split the cytoplasm into two membrane-bound portions. Binary fission is extremely fast compared to the rates of cell division in eukaryotes. Eukaryotic cell division is a more complex process known as the cell cycle; DNA replication occurs during a phase of this cycle known as S phase, whereas the process of segregating chromosomes and splitting the cytoplasm occurs during M phase.
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The cell wall of both gram-positive and gram-negative bacteria is a tight covalently bound and cross-linked peptidoglycan network and essential for bacterial growth, cell division and cellular structure. Therefore, bacteria need enzymes that can cleave the cell wall during bacterial growth and cell division. The cell wall of bacteria is built up in two steps from the outside of the cell. In the first step, molecules of disaccharide units linked with peptides on their ends are transported from the cytoplasm of the bacteria and joined together on the outside of the wall by a transglycolase.
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It was at Woods Hole in the Summer of 1982, using the sea urchin (Arbacia punctulata) egg as his model organism, that he discovered the cyclin molecule. Hunt was a keen cyclist and named the protein based on his observation of the cyclical changes in its levels. Cyclins are proteins that play a key role in regulating the cell-division cycle.The Nobel Prize in Physiology or Medicine 2001 Illustrated Lecture Hunt found that cyclins begin to be synthesised after the eggs are fertilised and increase in levels during interphase, until they drop very quickly in the middle of mitosis in each cell division.
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FtsZ is found in nearly all Bacteria and Archaea, where it functions in cell division, localizing to a ring in the middle of the dividing cell and recruiting other components of the divisome, the group of proteins that together constrict the cell envelope to pinch off the cell, yielding two daughter cells. FtsZ can polymerize into tubes, sheets, and rings in vitro, and forms dynamic filaments in vivo. TubZ functions in segregating low copy-number plasmids during bacterial cell division. The protein forms a structure unusual for a tubulin homolog; two helical filaments wrap around one another.
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Some cells, however, have numerous cilia which they use to generate directed fluid flow. The examples include epithelial cells of the respiratory tract in which multiple cilia are used for mucus clearance, the oviduct, in which cilia help the egg migrate to the uterus, and others. Each cilium has a basal body formed from a centriole to which it is anchored and from which it starts to grow after each cell division, when a new daughter cell is formed. Centrioles typically replicate once during cell division, thus allowing for only one cilium for a daughter cell.
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These are small nuclei containing one chromosome or part of a chromosome which did not get to one of the cell poles during cell division. The CBMN test is based on the fact that only dividing cells can express micronuclei, which means that only in those cells, chromosome damage can be detected. Because genotoxicity causes abnormalities in cell division, micronuclei can be detected in binucleated cells. Cytokinesis, which is the next stage, is inhibited by cytochalasin B. A key advantage of this method is that it allows simultaneous detection of multiple molecular events leading to chromosome damage and chromosomal instability.
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Before the introduction of the Nucleofector Technology, efficient gene transfer into primary cells had been restricted to the use of viral vectors, which typically involve disadvantages such as safety risks, lack of reliability, and high cost. The non-viral gene transfer methods available were not suitable for the efficient transfection of primary cells. Non-viral delivery methods may require cell division for completion of transfection, since the DNA enters the nucleus during breakdown of the nuclear envelope upon cell division or by a specific localization sequence. Optimal nucleofection conditions depend upon the individual cell type, not on the substrate being transfected.
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Cytokinesis in terrestrial plants occurs by cell plate formation. This process entails the delivery of Golgi-derived and endosomal vesicles carrying cell wall and cell membrane components to the plane of cell division and the subsequent fusion of these vesicles within this plate. After formation of an early tubulo-vesicular network at the center of the cell, the initially labile cell plate consolidates into a tubular network and eventually a fenestrated sheet. The cell plate grows outward from the center of the cell to the parental plasma membrane with which it will fuse, thus completing cell division.
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Cell division: Xenopus egg extracts have allowed the study of many complicated cellular events in vitro. Because egg cytosol can support successive cycling between mitosis and interphase in vitro, it has been critical to diverse studies of cell division. For example, the small GTPase Ran was first found to regulate interphase nuclear transport, but Xenopus egg extracts revealed the critical role of Ran GTPase in mitosis independent of its role in interphase nuclear transport. Similarly, the cell-free extracts were used to model nuclear envelope assembly from chromatin, revealing the function of RanGTPase in regulating nuclear envelope reassembly after mitosis.
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Mammals have two isoenzymes that are chemically very different, Thymidine Kinase 1 (TK1) and Thymidine Kinase 2 (TK2). The former was first found in fetal tissue, the second was found to be more abundant in adult tissue, and so initially they were termed fetal and adult thymidine kinases. Soon it was shown that TK1 is present in the cytoplasm only in anticipation of cell division (cell cycle-dependent) whereas the presence of TK2, which is located in the mitochondria, is cell cycle-independent. TK1 is synthesized by the cell during the S phase of cell division.
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Kim identified the cancer cell growth inhibition mechanism of magnetic-based cell division difference. Dispersed by the static magnetic field, the core protein GCP3 in spindle formation, during cell division cycle, was identified for the first time in the world. This contributed to establish the scientific basis on the availability to the magnetic field for future anti-cancer therapy. From Harvard MGH research exchanges, the treatment of nerve cell to nerve cell turning the magnetic field grow into the direction perpendicular to the magnetic field that can be used in a certain direction based on research data.
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Three types of cell division: binary fission (taking place in prokaryotes), mitosis and meiosis (taking place in eukaryotes). When cells are ready to divide, because cell size is big enough or because they receive the appropriate stimulus, they activate the mechanism to enter into the cell cycle, and they duplicate most organelles during S (synthesis) phase, including their centrosome. Therefore, when the cell division process will end, each daughter cell will receive a complete set of organelles. At the same time, during S phase all cells must duplicate their DNA very precisely, a process termed DNA replication.
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Not only have analogues for all major cytoskeletal proteins in eukaryotes been found in prokaryotes, cytoskeletal proteins with no known eukaryotic homologues have also been discovered. Cytoskeletal elements play essential roles in cell division, protection, shape determination, and polarity determination in various prokaryotes.
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In other cases, auxin-promoted cell division and cell expansion may be closely sequenced within the same tissue (root initiation, fruit growth). In a living plant, auxins and other plant hormones nearly always appear to interact to determine patterns of plant development.
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Arginine plays an important role in cell division, wound healing, removing ammonia from the body, immune function, and the release of hormones. It is a precursor for the synthesis of nitric oxide (NO), making it important in the regulation of blood pressure.
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As FA is now known to affect DNA repair, specifically homologous recombination, and given the current knowledge about dynamic cell division in the bone marrow, patients are consequently more likely to develop bone marrow failure, myelodysplastic syndromes, and acute myeloid leukemia (AML).
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Dr. Marc Ladanyi at Memorial Sloan-Kettering Cancer Center, in New York City, has pioneered this work. The resultant fusion protein ASPL–TFE3 is a rogue transcription factor that is the driver of aberrant cellular behavior including uncontrolled cell division and enhanced angiogenesis.
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Pefloxacin is a broad-spectrum antibiotic that is active against both Gram-positive and Gram-negative bacteria. It functions by inhibiting DNA gyrase, a type II topoisomerase, and topoisomerase IV, which is an enzyme necessary to separate, replicated DNA, thereby inhibiting cell division.
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The cells are coccoid. Cells are 1-2.5 μm. Cell division is carried out in two or three successive planes, such that tetrads or packets of eight or more cells are formed. S. ureae forms endospores (like all species of the genus).
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Gerlich's work investigates the spatial organization and biomechanics of human chromosomes. By combining cell biology, biophysics, biochemistry, and computer science approaches, he aims to elucidate how chromosomes reorganize during cell cycle progression and how they rebuild a cell nucleus after cell division.
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This increase in size forces the cell to increase the number of paramylon storage granules and develop a polysaccharide mucilaginous wall for protection until it enters a more habitable environment. In addition, cell division continues to take place even as a reproductive cyst.
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The importance of this protein is vital, without its help in DNA replication, cell division and other crucial processes could not occur. This protein domain is thought to be part of a much larger protein complex which includes other proteins such as SeqB.
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The two type IIA topoisomerases, IIα and IIβ, are used to unlink intertwined daughter duplexes, as well as assist in cell division and suppression of recombination, respectively. Type IIIα and IIIβ are thought to work in embryogenesis and interact with helicases, respectively.
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Bacteria are often viewed as the main consumers of DOC, but they can also produce DOC during cell division and viral lysis.Iturriaga, R., and Zsolnay, A. (1981). Transformation of some dissolved organic compounds by a natural heterotrophic population. Mar. Biol. 62, 125–129.
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Gey is also noted to be one of the first to document cell division and growth on film. He devised a time lapse camera that stood twelve feet, built out of spare parts from a nearby junkyard, with a temperature controlled incubator.
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The pure culture, cell division and the ultrastructure of A. vulgares hyphae and mycelia have been studied and described in search of potentially useful characters for phylogenetic analysis. When grown in culture, the fungus can be induced to produce fruit bodies under suitable conditions.
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Mitochondria divide by binary fission, similar to bacterial cell division. The regulation of this division differs between eukaryotes. In many single-celled eukaryotes, their growth and division are linked to the cell cycle. For example, a single mitochondrion may divide synchronously with the nucleus.
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Docetaxel is in the taxane family of medications. It works by disrupting the normal function of microtubules and thereby stopping cell division. Docetaxel was patented in 1986 and approved for medical use in 1995. It is on the World Health Organization's List of Essential Medicines.
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However, inhibiting telomerase alone is not enough to destroy large tumors. It must be combined with surgery, radiation, chemotherapy or immunotherapy. Cells may reduce their telomere length by only 50-252 base pairs per cell division, which can lead to a long lag phase.
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Ciprofloxacin is a broad-spectrum antibiotic of the fluoroquinolone class. It is active against some Gram-positive and many Gram-negative bacteria. It functions by inhibiting a type II topoisomerase (DNA gyrase) and topoisomerase IV, necessary to separate bacterial DNA, thereby inhibiting cell division.
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The eggs hatch after no more than 14 days, with the young already possessing their full complement of adult cells. Growth to the adult size occurs by enlargement of the individual cells (hypertrophy), rather than by cell division. Tardigrades may molt up to 12 times.
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However, ORF3 also interacts with pPirh2 at the same region as p53 and causes an upregulation of p53 expression. This increase in p53 stops the cell division cycle and the result of this is p53 mediated apoptosis, which releases PCV into the extracellular environment.
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Excess HIF stimulates cells to divide and triggers the production of blood vessels when they are not needed. Rapid and uncontrolled cell division, along with the formation of new blood vessels, can lead to the development of tumors in people with hereditary paraganglioma-pheochromocytoma.
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Mitotic homologous recombination occurs mainly between sister chromatids subsequent to replication (but prior to cell division). Inter-sister homologous recombination is ordinarily genetically silent. During mitosis the incidence of recombination between non-sister homologous chromatids is only about 1% of that between sister chromatids.
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INCENP has been shown to interact with H2AFZ, Survivin and CDCA8. The ARK binding region has been found to be necessary and sufficient for binding to aurora-related kinase. This interaction has been implicated in the coordination of chromosome segregation with cell division in yeast.
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Embryology Atlas Through the processes of compaction, cell division, and blastulation, the conceptus takes the form of the blastocyst by the fifth day of development, just as it approaches the site of implantation.Blackburn, Susan. Maternal, Fetal, & Neonatal Physiology, p. 80 (Elsevier Health Sciences 2007).
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Halteria can reproduce asexually by transverse binary fission. During this replication the majority of the ciliature that will be present on the daughter cells is formed de novo.Song, W. (1993). Studies on the cortical morphogenesis during cell division in Halteria grandinella (Muller, 1773) (Ciliophora, Oligotrichida).
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USP domain genes are regulated by a number of proteins involved with growth, DNA repair and cell division. Notable positive regulation occurs via the action of ppGpp, RecA and FtsZ dependent regulatory pathways. USP domain genes are also under the negative control of FadR.
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The gene encoding Pin1 was identified in 1996 as a result of a genetic/biochemical screen for proteins involved in mitotic regulation. It was found to be essential for cell division in some organisms. By 1999, however, it was apparent that Pin1 knockout mice had a surprisingly mild phenotype, indicating that the enzyme was not required for cell division per se. Further studies later found that loss of Pin1 in mice displays are not only neuronal degenerative phenotypes but also several abnormalities, similar to those of cyclin D1-null mice, suggesting the conformation changes mediated by Pin1 may be crucial for cell normal function.
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Loss of SMARCB1 function is the most common genetic mutation observed in epithelioid sarcoma, and this dysfunction is likely a major driver of disease progression. SMARCB1 is a core protein subunit of the 15 subunit SWI/SNF (or BAF) complex involved in regulating the nucleosome architecture of our genome and has been shown to be a potent tumor suppressor gene, meaning that its primary role is to control cell division and to even halt division under appropriate circumstances (i.e. signals to over-replicate). As this tumor suppressor is commonly inactivated in epithelioid sarcoma, cell division can fail to appropriately halt, resulting in unregulated cellular growth and the formation of cancer tumors.
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Although L-forms can develop from Gram- positive as well as from Gram-negative bacteria, in a Gram stain test, the L-forms always colour Gram-negative, due to the lack of a cell wall. The cell wall is important for cell division, which, in most bacteria, occurs by binary fission. This process usually requires a cell wall and components of the bacterial cytoskeleton such as FtsZ. The ability of L-form bacteria to grow and divide in the absence of both of these structures is highly unusual, and may represent a form of cell division that was important in early forms of life.
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There the plasmids are segregated and can replicate without interference from the chromosomal DNA. During cell division many plasmids are plagued with low copy numbers and thus evolved active segregation to avoid plasmid loss during cell division The process of this segregation is carried out by a small number of components, three to be exact, in the DNA, with incredible efficiency. The three components, a parC DNA site, and two proteins parR and parM all combine to create the ParMRC system, a type II plasmid partitioning system. The process by which the plasmids are segregated from the chromosomal DNA is not an extremely complicated one and contains just three components.
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After 20 doublings of the mixed culture, only female cells remained. Cell division ceased in the unmixed control cultures at the anticipated times; When the male control culture stopped dividing, only female cells remained in the mixed culture. This suggested that technical errors or contaminating viruses were unlikely explanations as to why cell division ceased in the older cells, and proved that unless the virus or artifact could distinguish between male and female cells (which it could not) then the cessation of normal cell replication was governed by an internal counting mechanism. These results disproved Carrel's immortality claims and established the Hayflick limit as a credible biological theory.
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Asymmetric ring structure of Vps4 required for ESCRT III disassembly The ESCRT pathway facilitates formation of vesicles that bud into the endosome, neuronal pruning, reassembly of the post-mitotic nuclear envelope and final stage cell division (cytokinetic abscission). Cytokinetic abscission completes the separation of the two daughter cells, and also helps to coordinate a checkpoint that delays cell division until mitotic processes are completed successfully. In some cancer cells, this pathway doesn’t function correctly. Sundquist’s lab is studying these processes by determining the structures and functions of individual ESCRT proteins and the cofactors they recruit to help mediate abscission and the abscission checkpoint, and the signaling pathways that control their activities.
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Cytokinesis illustration Cilliate undergoing cytokinesis, with the cleavage furrow being clearly visible Cytokinesis is not a phase of mitosis but rather a separate process, necessary for completing cell division. In animal cells, a cleavage furrow (pinch) containing a contractile ring develops where the metaphase plate used to be, pinching off the separated nuclei. In both animal and plant cells, cell division is also driven by vesicles derived from the Golgi apparatus, which move along microtubules to the middle of the cell. In plants, this structure coalesces into a cell plate at the center of the phragmoplast and develops into a cell wall, separating the two nuclei.
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Work in Botchan's laboratory focuses on studying the regulation of DNA replication during cell division, using Drosophila embryos as a model organism. The group has been particularly interested in the mechanisms of genomic integration of DNA oncoviruses and in the characterization of the eukaryotic origin recognition complex.
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Vinca alkaloids prevent the assembly of microtubules, whereas taxanes prevent their disassembly. Both mechanisms cause defective mitosis. Anti-microtubule agents are plant-derived chemicals that block cell division by preventing microtubule function. Microtubules are an important cellular structure composed of two proteins, α-tubulin and β-tubulin.
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Bryocella elongata is a bacterium, a type species of genus Bryocella. Cells are Gram-negative, non-motile pink-pigmented rods that multiply by normal cell division and form rosettes. The type strain is SN10(T). B. elongata was first isolated in 2011 from a methanotropic enrichment culture.
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The objective of the plant embryogenesis (PEMBSIS) experiment was to evaluate whether space flight affected the pattern and developmental progression of embryonic daylilies from one well-defined stage to another. It also examined whether cell division (mitosis) and chromosome behavior were modified by the space environment.
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Fetal cells are most sensitive to carcinogens during the early stages of gestation. Notably, early in the gestational period, there is a high rate of cell division. Additionally, the cells exhibit undifferentiated characteristics. These compounding factors illustrate the basis for this heightened cellular sensitivity to genotoxic agents.
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The cyst is covered in two envelopes. The outer envelope is softer and used to attach to a substrate such as filamentous food (algae). A stalk may or may not be present. The inner envelope is stronger and surrounds the cell while cell division takes place.
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Phosphoric acid makes up part of the cell nucleus and reproductive system. Phosphoric acid is involved in photo phosphorylation and electron transport in photosynthesis, anabolite transport and in protein synthesis. Deficiency hinders cell division and reproduction. Symptoms first appear on the petiole and veins of older leaves.
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Loss of Wee1 function will produce smaller than normal daughter cell, because cell division occurs prematurely. Its name is derived from the Scottish dialect word wee, meaning small - its discoverer Paul Nurse was working at the University of Edinburgh in Scotland at the time of discovery.
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GVAX is a cancer vaccine composed of whole tumor cells genetically modified to secrete the immune stimulatory cytokine, granulocyte-macrophage colony- stimulating factor (GM-CSF), and then irradiated to prevent further cell division. The product exists as both autologous (patient specific) and allogeneic (non-patient specific) therapy.
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Eleuteroschisis is asexual reproduction in dinoflagellates in which the parent organism completely sheds its theca (i.e. undergoes ecdysis) either before or immediately following cell division. Neither daughter cell inherits part of the parent theca.FENSOME R.A., TAYLOR F.J.R., NORRIS G., SARJEANT W.A.S., WHARTON D.I. & WILLIAMS G.L. 1993.
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Centrosome disorientation refers to the loss of orthogonality between the mother and daughter centrioles. Once disorientation occurs, the mature centriole begins to move toward the cleave furrow. It has been proposed that this movement is a key step in abscission, the terminal phase of cell division.
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The cortex enables the cell to resist externally applied forces and to exert mechanical work. As such, it plays a role in normal physiology during events involving cell deformation such as cell division and migration, and in diseases such as cancer where cell shape is often deregulated.
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TYK This disorder results from mutations in the proximal tyrosine kinase domain of the FGFR3 gene. This gene plays an important role in embryonic development, playing a part in regulating activities such as cell division, migration and differentiation. Hypochondroplasia can result from p. Lys650Asn as well.
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A. tumefaciens grows optimally at 28 °C. The doubling time can range from 2.5–4h depending on the media, culture format, and level of aeration. At temperatures above 30 °C, A. tumefaciens begins to experience heat shock which is likely to result in errors in cell division.
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Inside the cells they undergo spontaneous transformation into oval-shaped amastigotes. Granulocytes selectively kill the promastigotes by oxidative mechanism, while amastigotes are resistant. Then the surviving amastigotes undergo cell division using simple binary fission. Multiplication continues until the host cell can no longer hold and ruptures.
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Because Hoechst stains bind to DNA, they interfere with DNA replication during cell division. Consequently, they are potentially mutagenic and carcinogenic, so care should be used in their handling and disposal. Hoechst stain is used to sort sperm in livestock and humans. Its safety has been debated.
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Unlike other fluorescent proteins, PAFPs can be used as selective optical markers. An entirely labeled cell can be followed to assess cell division, migration, and morphology. Very small volumes containing PAFPs can be activated with a laser. In these cases, protein trafficking, diffusion, and turnover can be assessed.
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His proposers were James Ritchie, John Gaddum, Sir Maurice Yonge and Harold Callan. He won the Society's Makdougall Brisbane Prize for 1970/72. In 1962 he was elected a Fellow of the Royal Society of London. His academic work was on the mechanisms of cell division and fertilisation.
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Some genetic tracing studies utilize cre-lox recombination to bind a promoter to a reporter gene, such as lacZ or GFP gene. This method can be used for long term quantification of cell division and labeling, whereas the previously mentioned procedures are only useful for short-term quantification.
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Somatic cells that have divided many times will have accumulated DNA mutations and would be more susceptible to becoming cancerous if cell division continued. As such, it is becoming apparent that senescent cells undergo conversion to an immunologic phenotype that enables them to be eliminated by the immune system.
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Peters characterized the regulation and operating principle of a number of proteins that are responsible for the correct chromosome segregation during mitosis. Using the enzyme Polo-like Kinase 1 (Pik1), Peters characterized a cell division enzyme that has shown to be a promising target for chemotherapy against certain cancers.
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Polytene chromosomes were originally observed in the larval salivary glands of Chironomus midges by Balbiani in 1881. They form through repeated rounds of DNA replication without cell division, resulting in characteristic light and dark banding patterns which can be used to identify inversions and deletions which allow species identification.
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Cell division can be characterized by the activity of that enzyme. FLT is phosphorylated as though it were thymidine, and is subsequently incorporated into DNA. Thymidine is essential for DNA replication. Considering that FLT lacks a 3′-hydroxy group, transcription of DNA is impeded following incorporating of FLT.
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Dacarbazine works by methylating guanine at the O-6 and N-7 positions. Guanine is one of the four nucleotides that makes up DNA. The methylated DNA strands stick together such that cell division becomes impossible. This affects cancer cells more than healthy cells because cancer cells divide faster.
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Beta-catenin has also been implicated in regulation of cell fates through asymmetric cell division in the model organism C. elegans. Similarly to the Xenopus oocytes, this is essentially the result of non-equal distribution of Dsh, Frizzled, axin and APC in the cytoplasm of the mother cell.
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The centrosome replicates during the S phase of the cell cycle. During the prophase in the process of cell division called mitosis, the centrosomes migrate to opposite poles of the cell. The mitotic spindle then forms between the two centrosomes. Upon division, each daughter cell receives one centrosome.
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Eukaryotes can reproduce both asexually through mitosis and sexually through meiosis and gamete fusion. In mitosis, one cell divides to produce two genetically identical cells. In meiosis, DNA replication is followed by two rounds of cell division to produce four haploid daughter cells. These act as sex cells (gametes).
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Remak published observations in 1852 on cell division, claiming Schleiden and Schawnn were incorrect about generation schemes. He instead said that binary fission, which was first introduced by Dumortier, was how reproduction of new animal cells were made. Once this tenet was added, the classical cell theory was complete.
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Triacontanol also increases the growth of a cell in vitro by increasing the cell number in the culture. It can be attributed to the increase protein formation and rapid cell division induced by triacontanol.Roger Hangarter, Stanley K. Ries, Peter Carlson. Effect of Triacontanol on Plant Cell Cultures in vitro.
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Cryptophycins are potent microtubule inhibitors, with a mechanism of action similar to that of vinca alkaloids. Treatment of cells with cryptophycins depletes microtubules through interaction with tubulin, thereby preventing cell division. Cryptophycins are capable of inducing apoptosis, possibly through other mechanisms in addition to that mediated by microtubule inhibition.
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The existence of non- bilayer lipid formations with important biological functions was confirmed subsequent to publication of the fluid mosaic model. These membrane structures may be useful when the cell needs to propagate a non bilayer form, which occurs during cell division and the formation of a gap junction.
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Granule cell precursors (GCPs) of the cerebellum, after undergoing symmetric cell division in the external granule-cell layer (EGL), migrate into the internal granule-cell layer (IGL) where they downregulate GluN2B and activate GluN2C, a process that is independent of neuregulin beta signaling through ErbB2 and ErbB4 receptors.
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The focus of Schaechter's research group involved studying bacterial growth and cell division, with particular interest in the involvement of bacterial cell membranes in division. Among the notable discoveries of the group was the association of the E. coli origin of replication with the cell membrane when hemimethylated.
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In mice, hypomorphic mutations in condensin II subunits cause specific defects in T cell development, leading to T cell lymphoma. It is interesting to note that cell types with specialized cell division modes, such as neural stem cells and T cells, are particularly susceptible to mutations in condensin subunits.
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Plant cells are fixed with regards to their neighbor cells within the tissues they are growing in. In contrast to animals where certain cells can migrate within the embryo to form new tissues, the seedlings of higher plants grow entirely based on the orientation of cell division and subsequent elongation and differentiation of cells within their cell walls. Therefore, the accurate control of cell division planes and placement of the future cell wall in plant cells is crucial for the correct architecture of plant tissues and organs. The preprophase stage of somatic plant cell mitosis serves to establish the precise location of the division plane and future cell wall before the cell enters prophase.
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Work by Fairclough, Dayel and King suggests that S. Rosetta can exist in either single-cellular form or in colonies of 4-50 cells, which arrange themselves in tight knit packs of spheres. This was established by performing an experiment involving the introduction of prey bacterium Algoriphagus species to a sample of uni-celled S. Rosetta organism and monitored the activity for 12 hours. Results of this study demonstrated that cell colonies were formed through cell-division of the initial solitary S. Rosetta cell rather than by cell aggregation. Further studies to support the theory of cell-proliferation were done by introducing then removing the drug aphidicolin which serves to block cell-division.
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As pointed out by Vijg, genome repair and maintenance is beneficial early in life by swiftly eliminating DNA damage or damaged cells. However, studies of DNA repair in the brain and in muscle indicate that the transition from mitotic cell division to the post-mitotic condition that occurs early in life is accompanied by a reduction in DNA repair. The reduced expression of DNA repair is presumably part of an evolutionary adaptation for diverting the resources of the cell that were previously used for DNA repair, as well as for replication and cell division, to more essential neuronal and muscular functions. The harmful effect of this genetically controlled reduction in expression is to allow increased accumulation of DNA damage.
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Some embryos have been interpreted as colonies of sulfur-reducing bacteria, a claim that cannot be upheld in all cases. Embryo fossils found in Doushantuo Formation of southern China exhibit occasional asynchronous cell division, common in modern embryos, implying that sophisticated mechanisms for differential cell division timing and embryonic cell lineage differentiation evolved before 551 million years ago. However, embryos composed of hundreds to more than ~1000 cells still show no evidence of blastocoel formation or the organization of blastomeres into epithelia – epithelialization should be underway in modern embryos with >100 cells. Features preserved on Doushantuo embryos are compatible with metazoans (animals), but the absence of epithelialization is consistent only with a stem-metazoan affinity.
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In both invertebrates and mammals, Numb is localized using the Pins/GαI complex and the PAR complex of Bazooka (Par3 in mammals), Par6, and aPKC (atypical protein kinase C). In the sensory organ precursor (SOP) cell, the PAR proteins localize to the posterior pole of the cell, and the Pins/GαI complex is localized to the anterior pole of the cell. This results in an anterior/posterior cell division with daughter cells of similar size. In neuroblasts, both complexes are localized to the apical cortex, causing apical/basal cell division and daughter cells exhibiting strong size asymmetry. In the SOP, one mechanism for Numb localization has been proposed based on the PAR complex.
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During chromosome replication, the enzymes that duplicate DNA cannot continue their duplication all the way to the end of a chromosome, so in each duplication the end of the chromosome is shortened (this is because the synthesis of Okazaki fragments requires RNA primers attaching ahead on the lagging strand). The telomeres are disposable buffers at the ends of chromosomes which are truncated during cell division; their presence protects the genes before them on the chromosome from being truncated instead. The telomeres themselves are protected by a complex of shelterin proteins, as well as by the RNA that telomeric DNA encodes (TERRA). Over time, due to each cell division, the telomere ends become shorter.
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In the early 1970s, Russian theorist Alexei Olovnikov first recognized that chromosomes could not completely replicate their ends. Building on this, and to accommodate Leonard Hayflick's idea of limited somatic cell division, Olovnikov suggested that DNA sequences are lost every time a cell replicates until the loss reaches a critical level, at which point cell division ends. In 1975–1977, Elizabeth Blackburn, working as a postdoctoral fellow at Yale University with Joseph G. Gall, discovered the unusual nature of telomeres, with their simple repeated DNA sequences composing chromosome ends. Blackburn, Carol Greider, and Jack Szostak were awarded the 2009 Nobel Prize in Physiology or Medicine for the discovery of how chromosomes are protected by telomeres and the enzyme telomerase.
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Diplontic life cycle Haplontic life cycle. Meiosis occurs in eukaryotic life cycles involving sexual reproduction, consisting of the constant cyclical process of meiosis and fertilization. This takes place alongside normal mitotic cell division. In multicellular organisms, there is an intermediary step between the diploid and haploid transition where the organism grows.
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This overactive protein directs the cell to grow and divide in the absence of outside signals, leading to uncontrolled cell division and the formation of a tumor. Mutations in the HRAS gene also have been associated with the progression of bladder cancer and an increased risk of tumor recurrence after treatment.
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The protein also translocates to the nucleus in response to treatment with complement system proteins, and can associate with and increase the kinase activity of cell division cycle 2 protein. In different assays and cell types, overexpression of this protein has been shown to activate or suppress cell cycle progression.
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Zeatin is a cytokinin derived from adenine, which occurs in the form of a cis- and a trans-isomer and conjugates. Zeatin was discovered in immature corn kernels from the genus Zea. It promotes growth of lateral buds and when sprayed on meristems stimulates cell division to produce bushier plants.
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The top-down approach is generally considered as the more plausible means of generating extra-numerary chromosomes for the use of genetic engineering of plants. In particular it is useful because their stability during cell division has been demonstrated. The limitation of this approach is that it is labor-intensive.
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The Department of Mechanistic Cell Biology aims to better understand the molecular mechanisms of cell division and their regulation. The main focus is on the key proteins that control the division of chromosomes during mitosis, a process that separates sister chromatids into two identical daughter cells, thereby maintaining chromosome stability.
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HRR can accurately repair DSBs in one sister chromosome by using intact information from the other sister chromosome. Cells in the G1 phase of the cell cycle (i.e. after metaphase/cell division but prior the next round of replication) have only one copy of each chromosome (i.e. sister chromosomes aren’t present).
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This zone is permeated with infection threads full of bacteria. The plant cells are larger than in the previous zone and cell division is halted. ::Interzone II–III—Here the bacteria have entered the plant cells, which contain amyloplasts. They elongate and begin terminally differentiating into symbiotic, nitrogen-fixing bacteroids.
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The sterile cells may form a central support structure or surround the spermatogenous tissue as a protective jacket. The spermatogenous cells give rise to spermatids via mitotic cell division. In some bryophytes, the antheridium is borne on an antheridiophore, a stalk-like structure that carries the antheridium at its apex.
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Polo-like kinases (Plks) are regulatory serine/threonin kinases of the cell cycle involved in mitotic entry, mitotic exit, spindle formation, cytokinesis, and meiosis.Barr, Francis A., Herman HW Silljé, and Erich A. Nigg. "Polo-like kinases and the orchestration of cell division." Nature reviews Molecular cell biology5.6 (2004): 429-441.
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Daniel Louvard is a French scientist with the Department of Cell Biology in the Curie institute, Paris. In 1996 he won the Richard Lounsbery Award jointly with Jacques Pouysségur for "their contributions to the study of the regulation of cell division and differentiation."Richard Lounsbery Award. National Academy of Sciences.
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A mitogen is a peptide or small protein that induces a cell to begin cell division: mitosis. Mitogenesis is the induction (triggering) of mitosis, typically via a mitogen. The mechanism of action of a mitogen is that it triggers signal transduction pathways involving mitogen-activated protein kinase (MAPK), leading to mitosis.
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Cells tend to divide along their long axis according to the so-called Hertwig rule. The axis of cell division is determined by the orientation of the spindle apparatus. Cells divide along the line connecting two centrosomes of the spindle apparatus. After formation, the spindle apparatus undergoes rotation inside the cell.
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Tumor development is a complex process that requires cell division, growth, and survival. One approach used by tumors to upregulate growth and survival is through autocrine production of growth and survival factors. Autocrine signaling plays critical roles in cancer activation and also in providing self-sustaining growth signals to tumors.
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This prevents the incremental shortening of telomeres that is implicated in aging and eventual cell death. In this way, the cells circumvent the Hayflick limit, which is the limited number of cell divisions that most normal cells can undergo before becoming senescent. The result is unlimited cell division and immortality.
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C1P was also previously reported to encourage cell division (mitogenic) in fibroblasts, block apoptosis by inhibiting acid SMase in white blood cells within tissues (macrophages) and increase intracellular free calcium concentrations in thyroid cells. C1P also has known roles in vesicular trafficking, cell survival, phagocytosis ("cell eating") and macrophage degranulation.
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The cell cycle. Many tumor suppressors work to regulate the cycle at specific checkpoints in order to prevent damaged cells from replicating. A tumor suppressor gene, or anti-oncogene, is a gene that regulates a cell during cell division and replication. If the cell grows uncontrollably, it will result in cancer.
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One of Mogilner's research topics is the mitotic spindle and how it is assembled. The mitotic spindle is what pulls conjoined chromosomes apart during cell division. Mogilner hypothesized that the chromosomes were surrounded by proteins that directed the microtubules toward them. A few years after, research in Germany confirmed his prediction.
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ParD forms a dimer and also regulates its own promoter (parDE). As with CcdB the toxin target is DNA gyrase. Induction of ParE toxin results in inhibition of cell division but not cell growth. The parD and ccD systems are found to be strikingly similar in terms of their structures and actions.
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Timothy John Mitchison is a cell biologist and systems biologist and Hasib Sabbagh Professor of Systems Biology at Harvard Medical School in the United States. He is known for his discovery, with Marc Kirschner, of dynamic instability in microtubules, for studies of the mechanism of cell division, and for contributions to chemical biology.
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Ofloxacin is a broad-spectrum antibiotic that is active against both Gram-positive and Gram- negative bacteria. It functions by inhibiting two bacterial type II topoisomerases, DNA gyrase and topoisomerase IV. Topo IV is an enzyme necessary to separate (mostly in prokaryotes, in bacteria in particular) replicated DNA, thereby inhibiting bacterial cell division.
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CML, inhibited by _imatinib_ (small molecule). Molecular genetics has uncovered signalling networks that regulate cellular activities such as proliferation and survival. In a particular cancer, such a network may be radically altered, due to a chance somatic mutation. Targeted therapy inhibits the metabolic pathway that underlies that type of cancer's cell division.
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Vitamin A is an essential nutrient for mammals which takes form in either retinol or the provitamin beta-Carotene. It helps regulation of cell division, cell function, genetic regulation, helps enhance the immune system, and is required for brain function, chemical balance, growth and development of the central nervous system and vision.
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Archana Sharma was a renowned Indian botanist, cytogeneticist, cell biologist, and cytotoxicologist. Her widely recognized contributions include the study of speciation in vegetatively reproducing plants, induction of cell division in adult nuclei, the cause of polyteny in differentiated tissues in plants, cytotaxonomy of flowering plants, and the effect of arsenic in water.
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Reproduction in Thalassiosira weissflogii can be by either asexual or sexual means. The asexual phase involves cell division with each of the new individuals receiving one of the valves. This means that the offspring are of unequal sizes and successive generations tend to decrease in size. Large individuals can also reproduce sexually.
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Some use the term chromosome in a wider sense, to refer to the individualized portions of chromatin in cells, either visible or not under light microscopy. Others use the concept in a narrower sense, to refer to the individualized portions of chromatin during cell division, visible under light microscopy due to high condensation.
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This results in unregulated cell division and the formation of tumors. Other cancers show a loss of sensitivity of the G protein to the GAPs. These G proteins acquire missense mutations that disrupt the inherent GTPase activity of the proteins. The mutant G proteins are still bound by GAPs,Raepple, D. et al.
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Major advantages include the ability to introduce genetic information which is highly compatible with the host genome. This eliminates the risk of disrupting various important processes such as cell division and gene expression. With continued development, the future for use of minichromosomes may make a huge impact on the productivity of major crops.
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M. papillatus has a relatively complex reproductive cycle. Male gametophytes discharge nonflagellated sperm to drift in the current until they attach to the trichogynes of female plants. There the sperm perform mitosis without cell division, turning into a spermatium. Fertilisation then proceeds through a fertilization pore between the trichogyne and the spermatium.
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Studies show that cyanophage replication is driven by energy from photosynthetic metabolism of the host cell. Lysing of the host cell tends to occur after the completion of host DNA replication and immediately prior to cell division. This is due to the increased availability of resources for the replication of viral particles.
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To ensure proper cell division, the cell cycle utilizes numerous checkpoints to monitor cell progression and halt the cycle when processes go awry. These checkpoints include four DNA damage checkpoints, one unreplicated DNA checkpoint at the end of G2, one spindle assembly checkpoint in mitosis, and a chromosome segregation checkpoint during mitosis.
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Vitamin A is an essential nutrient for mammals which takes form in either retinol or the provitamin beta-Carotene. It helps regulation of cell division, cell function, genetic regulation, helps enhance the immune system, and is required for brain function, chemical balance, growth and development of the central nervous system and vision.
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It is often used to categorize fungi. In yeast, heterothallic cells have mating types a and α. An experienced mother cell (one that has divided at least once) will switch mating type every cell division cycle because of the HO allele. Sexual reproduction commonly occurs in two fundamentally different ways in fungi.
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It is also regulated by extracellular signaling. When B. subtilis populations sense waning conditions, they respond by undergoing asymmetric cell division. This ultimately produces spores that are adapted for dispersal and survival in unfavorable conditions. Sporulation in B. subtilis is mediated by CSF (sporulation factor), a pentapeptide cleaved from the precursor peptide PhrC.
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Not all ciliated cells extend to the luminal surface; such cells are capable of cell division providing replacements for cells lost or damaged. Pseudostratified epithelia function in secretion or absorption. If a specimen looks stratified but has cilia, then it is a pseudostratified ciliated epithelium, since stratified epithelia do not have cilia.
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Sexual reproduction in Oedogonium is oogamous; and can be monoecious or dioecious. Species may either be macrandrous (lacking dwarf males) or nannandrous (possessing dwarf males). Dwarf males are small, short, antheridium-producing filaments attached near the oogonia (female sex organ). These dwarf males are derived by repeated cell division of multiflagellate androspores.
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The spindle pole body (SPB) is the microtubule organizing center in yeast cells, functionally equivalent to the centrosome. Unlike the centrosome the SPB does not contain centrioles. The SPB organises the microtubule cytoskeleton which plays many roles in the cell. It is important for organising the spindle and thus in cell division.
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Traditionally, they were thought to be cytoskeletal elements and to consist primarily of vimentin. However, more recent research suggested that that was incorrect and that they may be composed of lipids arranged into bilayer membranes. They were also once thought to be related to centrioles, an organelle involved in cell division in eukaryotes.
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Along with the WUS gene the SHOOTMERISTEMLESS (STM) gene also represses the differentiation of the meristematic dome. This gene acts by inhibiting the possible differentiation of the stem cells but still allows cell division in the daughter cells, which, had they been allowed to differentiate, would have given rise to distinct organs.
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The miracidia simply pierce through the soft skin of the snail and move to the liver. Inside the snail, their cilia is cast off and extra-epithelial covering forms within 24 hours. Then they transform into sporocysts and undergo active cell division after two weeks. The mother sporocyst produces many daughter sporocysts.
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Tubulin inhibitors binding site Colchicine analogues blocks cell division by disrupting the microtubule. It has been reported that the β-subunit of tubulin is involved in colchicine binding. It binds to the soluble tubulin to form colchicine-tubulin complex. This complex along with the normal tubulins then undergoes polymerization to form the microtubule.
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It is thought to be subsequently degraded. Mutations in CENPF lead to impaired cell division during early development. Mitosis has been found to take longer when the gene is mutated. Microtubules are protein structures that are part of the cytoskeleton and are necessary for cells to have diverse, complex shapes and migratory ability.
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FtsK is a transmembrane protein composed of three domains: FtsKN, FtsKL, and FtsKC. Through its N- domain and C-domain FtsK works to coordinate cell division and chromosome differentiation. The FtsKN domain is embedded in the cellular membrane by four transmembrane α-helices. The FtsKL domain extends from the membrane into the cytoplasm.
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Fertilised eggs undergo cell division reaching a diameter of with the developing embryo at on the day before hatching. Upon hatching, the paralarvae are in mantle length (excluding tentacles), with fully functioning fins and ink sacs. They resemble miniature adults and are already strong swimmers. They exhibit schooling behaviour two weeks after hatching.
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Anillin specifically binds F-actin, rather than G-actin. Binding of F-actin by anillin only occurs during cell division. Anillin is also bundles actin filaments together. Amino acids 258-340 are sufficient and necessary for F-actin binding in Drosophila, but amino acids 246-371 are necessary to bundle actin filaments.
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Pederin blocks mitosis at levels as low as 1 ng/ml, by inhibiting protein and DNA synthesis without affecting RNA synthesis, prevents cell division, and has been shown to extend the life of mice bearing a variety of tumors. For these reasons, it has garnered interest as a potential anti-cancer treatment.
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An important aspect of plant behavior includes responding to directional stimuli, which requires changes in cellular signaling to control spatial elements. The integration of stimuli in plant cells is not fully understood, but the movement of the cell nucleus provides one example of a cellular process that underlies plant behavior, and highlights the importance of the cytoskeleton in solving spatial problems within the plant cell. Unlike the static nature typically depicted in textbooks, the plant cell nucleus is a highly dynamic structure, constantly moving around cell via actin networks and myosins. The nucleus undergoes a characteristic program during cell division to guide asymmetric cell division, but there are several stimuli that have been demonstrated to cause movements of the nucleus in the plant cell.
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The precise composition of the divisome and elongasome remains unknown, given that they are highly dynamic protein complexes which recruit and release certain proteins during cell division. However, more than 20 proteins are known to be part of the divisome in E. coli with a similar number of proteins in Gram-positive bacteria (such as Bacillus subtilis), although not all proteins are conserved across bacteria. Several other fts genes, such as ftsA, ftsW, ftsQ, ftsI, ftsL, ftsK, ftsN, and ftsB, were all found to be essential for cell division and to associate with the divisome complex and the FtsZ ring. FtsA protein binds directly to FtsZ in the cytoplasm, and FtsB, FtsL and FtsQ form an essential membrane-embedded subcomplex.
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Charles J. Sherr (born 1944) is the chair of the Tumor Cell Biology Department at St. Jude Children's Research Hospital. He studies tumor suppressor genes and cell division. Sherr received his AB from Oberlin College and his MD/PhD from New York University in 1972. He did a residency in pathology at Bellevue Hospital.
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Auxin stimulates cell elongation by stimulating wall-loosening factors, such as elastins, to loosen cell walls. The effect is stronger if gibberellins are also present. Auxin also stimulates cell division if cytokinins are present. When auxin and cytokinin are applied to callus, rooting can be generated if the auxin concentration is higher than cytokinin concentration.
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When cytokinin and auxin are present in equal levels, the parenchyma cells form an undifferentiated callus. More cytokinin induces growth of shoot buds, while more auxin induces root formation. Cytokinins are involved in many plant processes, including cell division and shoot and root morphogenesis. They are known to regulate axillary bud growth and apical dominance.
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Uninucleate amoebae are found more often in older cultures, with fragmented nucleoli, and usually later degrade. The presence of more than two nuclei is due to nuclear division, without cell division occurring immediately after. In the case of very rare trinucleate cells found by Brown et al. (2007), it is due to incomplete nuclear division.
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This gene is a member of the PAR6 family and encodes a protein with a PSD95/Discs-large/ZO1 (PDZ) domain, an OPR domain and a semi-Cdc42/Rac interactive binding (CRIB) domain. This cytoplasmic protein is involved in asymmetrical cell division and cell polarization processes as a member of a multi-protein complex.
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Previous research had suggested the condition linked to PTEN on chromosome 10, while other research pointed to chromosome 16. Prior to the findings regarding AKT1 in 2011, other researchers expressed doubt regarding the involvement of PTEN or GPC3, which codes for glypican 3 and may play a role in regulating cell division and growth regulation.
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Nonetheless, a few speculations for the causes have been made. During ovulation, the follicle ruptures resulting in epithelial cell damage. In order to heal the tissue and replace the damage, the cells undergoes cell division. Each time the cell divides, there is a possibility for mutations to occur and the chance of tumor formation increases.
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Induced cell cycle arrest is the use of a chemicals or genetic manipulation to artificially halt progression through the cell cycle. Cellular processes like genome duplication and cell division stop. It can be temporary or permanent. It is an artificial activation of naturally occurring cell cycle checkpoints, induced by exogenous stimuli controlled by an experimenter.
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In vivo, FtsZ forms filaments with a repeating arrangement of subunits, all arranged head-to-tail. These filaments form a ring around the longitudinal midpoint, or septum, of the cell. This ring is called the Z-ring. The GTP hydrolyzing activity of the protein is not essential to the formation of filaments or cell division.
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Similarly, instead of blocked cell division a cell may have reduced growth or metabolism ranging from nearly undetectable to almost normal. Thus, there is gradient from "essential" to completely non-essential, again depending on the condition. Some authors have thus distinguished between genes "essential for survival" and "essential for fitness". The role of genetic background.
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The ParMRC system is a mechanism for sorting DNA plasmids to opposite ends of a bacterial cell during cell division. It consists of three proteins: ParM, an actin-like protein that forms elongating polymers to push two plasmids apart, and ParR, and ParC, which bind plasmids to ParM filaments and help to polymerize ParM.
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John C. Reed (born October 11, 1958) is director of the Sanford-Burnham Medical Research Institute in La Jolla, San Diego, California and a pioneer in the field of apoptosis particularly with regard to cancer; he was studying oncogenes and discovered that some of them appeared to regulate cell death rather than cell division.
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Archaea is a domain of organisms that are prokaryotic, single- celled, and are thought to have developed 4 billion years ago. "They have no cell nucleus or any other organelles inside their cells."Archaea replicate asexually in a process known as binary fission. The cell division cycle includes when chromosomes of daughter cells replicate.
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In Bryopsida the leafy moss plant (q. v. "Thallus") is called gametophore. It is the adult form of the haploid gametophyte and develops from the juvenile form, the protonema, under the influence of phytohormones (mainly cytokinins). Whereas the filamentous protonema grows by apical cell division, the gametophore grows by division of three faced apical cells.
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Rather than describing a solution directly, an indirect encoding describes (either explicitly or implicitly) the process by which a solution is constructed. Often, but not always, these indirect encodings are based upon biological principles of development such as morphogen gradients, cell division and cellular differentiation (e.g. Doursat 2008), gene regulatory networks (e.g. Guo et al.
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Transcription can be silenced by histone modification (deacetylation and methylation), RNA interference, and/or DNA methylation. The gene expression patterns that define cell identity are inherited through cell division. This process is called epigenetic regulation. DNA methylation is reliably inherited through the action of maintenance methylases that modify the nascent DNA strand generated by replication.
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Shchelochkov O et al., Mosaicism for r(X) and der(X)del(X)(p11.23)dup(X)(p11.21p11.22) Provides Insight into the Possible Mechanism of Rearrangement, Molecular Cytogenetics 2008, 1:16 Small supernumary rings can also form, resulting in a partial trisomy. Ring chromosomes are unstable during cell division and can form interlocking or fused rings.
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Cartoon of the dividing epithelium cell surrounded by epithelium tissue. Spindle apparatus rotates inside the cell. The rotation is a result of astral microtubules pulling towards tri-cellular- junctions (TCJ), signaling centers localized at the regions where three cells meet. Cell division orientation is of major importance for tissue architecture, cell fates and morphogenesis.
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The two centrioles in the centrosome are tied to one another. The mother centriole has radiating appendages at the distal end of its long axis and is attached to its daughter at the proximal end. Each daughter cell formed after cell division will inherit one of these pairs. Centrioles start duplicating when DNA replicates.
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This particular species is anaerobic, rod-shaped and motile, thanks to possessing eight petritichous flagella. It grows optimally in 7.5% (wt/vol) sodium chloride solution. Albeit, salt shock is achieved with a concentration of 2-2.5M, affecting cell division and protein synthesis. Its reaction to heat shock is also associated with the medium's salt concentration.
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33 tumour-suppressing genes have been identified in humpback whales. These include atr, which detects damage to DNA and halts cell division; amer1, which slows cell growth; and reck, which limits metastasis. Humpbacks have multiple copies of genes that promote apoptosis. Gigantism in cetacea is associated with selective pressure in favor of tumor-suppressing genes.
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C. elegans. Fate mapping and cell lineage are similar but distinct topics, although there is often overlap. For example, the development of the complete cell lineage of C. elegans can be described as the fate maps of each cell division stacked hierarchically. The distinction between the topics is in the type of information included.
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The HeLa cell line was derived for use in cancer research. These cells proliferate abnormally rapidly, even compared to other cancer cells. Like many other cancer cells,The Nobel Prize in Physiology or Medicine 2009 on nobelprize.org HeLa cells have an active version of telomerase during cell division, which copies telomeres over and over again.
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It works by interference with the normal function of microtubules during cell division. Paclitaxel was first isolated in 1971 from the Pacific yew and approved for medical use in 1993. Wayback machine It is on the World Health Organization's List of Essential Medicines. It has been made from precursors, and more recently through cell culture.
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The meristems, where plant cell division occurs, are the usual sites of galls, though insect galls can be found on other parts of the plant, such as the leaves, stalks, branches, buds, roots, and even flowers and fruits. Gall-inducing insects are usually species-specific and sometimes tissue-specific on the plants they gall.
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Guanine preferentially binds. Subsequent to formation of [PtCl(guanine-DNA)(NH3)2]+, crosslinking can occur via displacement of the other chloride, typically by another guanine. Cisplatin crosslinks DNA in several different ways, interfering with cell division by mitosis. The damaged DNA elicits DNA repair mechanisms, which in turn activate apoptosis when repair proves impossible.
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Cre recombinase plays important roles in the life cycle of the P1 bacteriophage. Upon infection of a cell the Cre-loxP system is used to cause circularization of the P1 DNA. In addition to this Cre is also used to resolve dimeric lysogenic P1 DNA that forms during the cell division of the phage.
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This happens during G2 phase of the cell cycle. Initially, cytoplasmic strands form that penetrate the central vacuole and provide pathways for nuclear migration. Actin filaments along these cytoplasmic strands pull the nucleus into the center of the cell. These cytoplasmic strands fuse into a transverse sheet of cytoplasm along the plane of future cell division, forming the phragmosome.
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The cDENN domain is the most highly conserved domain within DENN family proteins, and is also primarily coil in protein DENND1B, which has been crystallized and confirmed to interact with the guanine nucleotide exchange domain of Rab-35. LCHN also contains a Stability of Polarity Axis (SPA) region. that may allow it to play a role in cell division.
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The Eli Lilly natural products group found that alkaloids of the Madagascar periwinkle (Vinca rosea), originally discovered in a screen for anti-diabetic drugs, blocked proliferation of tumour cells. The antitumour effect of the vinca alkaloids (e.g. vincristine) was later shown to be due to their ability to inhibit microtubule polymerization alkaloys, and therefore cell division.
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A provirus is a virus genome that is integrated into the DNA of a host cell. Advantages include automatic host cell division results in replication of the virus's genes, and the fact that it is nearly impossible to remove an integrated provirus from an infected cell without killing the cell.Marcello A. "Latency: the hidden HIV-1 challenge." Retrovirology.
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In many organisms, there is asymmetric cell division, e.g. a stem cell dividing to produce one stem cell and one non-stem cell. The cellular debris that cells accumulate is not evenly divided between the new cells when they divide. Instead more of the damage is passed to one of the cells, leaving the other cell rejuvenated.
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This suggests cospeciation between Trichonympha and Endomicrobia by vertical inheritance. New daughter cells most likely inherit their parent cells’ Endomicrobia during cell division. This causes a lineage of Endomicrobia to be established and maintained in Trichonympha. It has also been found that the Endomicrobia found in Trichonympha are monophyletic, suggesting that Endomicrobia only entered into symbiosis with Trichonympha once.
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In the nematode worm Caenorhabditis elegans there are two genes coding for septins, and septin complexes contain the two different septins in a tetrameric UNC59-UNC61-UNC61-UNC59 complex. Septins in C.elegans concentrate at the cleavage furrow and the spindle midbody during cell division. Septins are also involved in cell migration and axon guidance in C.elegans.
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Dithiopyr acts as a root growth inhibitor, causing cessation of root elongation and inhibition of mitotic cell division. It inhibits formation of microtubules and spindle organizing centers. Dithiopyr may alter microtubule polymerization and stability by "interacting with microtubule associated proteins or microtubule organizing centers rather than interaction directly with tubulin." Mitotic cells are arrested in late prometaphase.
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Figure 9. Joining of single-ended double strand breaks could lead to rearrangements Without proper homologous recombination, chromosomes often incorrectly align for the first phase of cell division in meiosis. This causes chromosomes to fail to properly segregate in a process called nondisjunction. In turn, nondisjunction can cause sperm and ova to have too few or too many chromosomes.
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This allows Cdt1 to carry out its function during pre-RC assembly. When APCCdh1 becomes inactive due to phosphorylation of Cdh1 by G1/S cyclins, geminin activity is increased again. Additionally, Dbf4 stimulates Cell division cycle 7-related protein kinase (Cdc7) activity, which promotes activation of replication origins. APCCdh1 is thought to target Dbf4 for destruction.
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It has a typical diameter of 1 micrometre and a length of 3 to 5 micrometres. Aside from microtubules it also contains various proteins involved in cytokinesis, asymmetric cell division, and chromosome segregation. The midbody is important for completing the final stages of cytokinesis, a process called abscission, although its precise role in these processes is not clear.
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Blebbing also has important functions in other cellular processes, including cell locomotion, cell division, and physical or chemical stresses. Blebs have been seen in cultured cells in certain stages of the cell cycle. These blebs are used for cell locomotion in embryogenesis. The types of blebs vary greatly, including variations in bleb growth rates, size, contents, and actin content.
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In general, younger people tend to have more aggressive tumors. Most pituitary tumors arise spontaneously and are not genetically inherited. Many pituitary tumors arise from a genetic alteration in a single pituitary cell that leads to increased cell division and tumor formation. This genetic change, or mutation, is not present at birth but is acquired during life.
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Asymmetry in the synthesis of leading and lagging strands S phase (Synthesis Phase) is the phase of the cell cycle in which DNA is replicated, occurring between G1 phase and G2 phase. Since accurate duplication of the genome is critical to successful cell division, the processes that occur during S-phase are tightly regulated and widely conserved.
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Non-motile bacteria cannot recognize surfaces or aggregate together as easily as motile bacteria. During surface colonization bacteria cells are able to communicate using quorum sensing (QS) products such as N-acyl homoserine lactone (AHL). Once colonization has begun, the biofilm grows by a combination of cell division and recruitment. Polysaccharide matrices typically enclose bacterial biofilms.
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In the epithelium the cells 'reads' its shape through the specific cell junction called tricellular junctions (TCJ). TCJ provide mechanical and geometrical clues for the spindle apparatus to ensure that cell divide along its long axis. Several factors could regulate cell shape and therefore orientation of cell division. Among these factors is the anisotropic mechanical stress.
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This asymmetric cell division usually occurs early in embryogenesis. Positive feedback can create asymmetry from homogeneity. In cases where the external or stimuli that would cause asymmetry are very weak or disorganized, through positive feedback the system can spontaneously pattern itself. Once the feedback has begun, any small initial signaling is magnified and thus produces an effective patterning mechanism.
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Interleukin 21 (IL-21) is a protein that in humans is encoded by the IL21 gene. Interleukin-21 is a cytokine that has potent regulatory effects on cells of the immune system, including natural killer (NK) cells and cytotoxic T cells that can destroy virally infected or cancerous cells. This cytokine induces cell division/proliferation in its target cells.
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It develops sex organs that produce gametes, haploid sex cells that participate in fertilization to form a diploid zygote which has a double set of chromosomes. Cell division of the zygote results in a new diploid multicellular organism, the second stage in the life cycle known as the sporophyte. The sporophyte can produce haploid spores by meiosis.
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The ABL1 tyrosine kinase activity of BCR- ABL1 is elevated relative to wild-type ABL1. Since ABL activates a number of cell cycle-controlling proteins and enzymes, the result of the BCR-ABL1 fusion is to speed up cell division. Moreover, it inhibits DNA repair, causing genomic instability and potentially causing the feared blast crisis in CML.
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During neuroepithelial cell division, interkinetic nuclear migration allows the cells to divide unrestricted while maintaining a dense packing. During G1 the cell nucleus migrates to the basal side of the cell and remains there for S phase and migrates to the apical side for G2 phase. This migration requires the help of microtubules and actin filaments.
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Dileptus bodies are typically narrow or cylindrical, and have a macronucleus made up of more than a hundred scattered nodules. During cell division, these nodules divide individually. At the front end of the cell is a mobile proboscis. The cytostome is at the base of this organ and is well fortified with stiff microtubular rods (nematodesmata).
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Pendimethalin acts both pre-emergence, that is before weed seedlings have emerged, and early post-emergence. Pendimethalin inhibits root and shoot growth. It controls the weed population and prevents weeds from emerging, particularly during the crucial development phase of the crop. Its primary mode of action is to prevent plant cell division and elongation in susceptible species.
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The G. obscuriglobus genome was sequenced by the J. Craig Venter Institute. The bacterium has a large genome by the standards of other PVC bacteria, around 9 megabases, and contains about 8,000 genes. It has 67% GC content. It possesses unusual genetic infrastructure, lacking a key component of most bacterial cell division processes, the protein FtsZ.
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Cellular abnormalities found within the FDCS tumor have been exploited for diagnostic purposes. Characteristically, FDCS have mircotubuloreticular structures (MTRS) and increased levels of intracellular clusterin. MTRS contribute to microtubule formation of many structures, including the mitotic spindle, during cell division. This contributes to many of the hallmarks of cancer, including proliferative signaling, growth activation, and replicative immortality.
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Cancers and tumors are caused by a series of mutations. Each mutation alters the behavior of the cell somewhat. Carcinogenesis, also called oncogenesis or tumorigenesis, is the formation of a cancer, whereby normal cells are transformed into cancer cells. The process is characterized by changes at the cellular, genetic, and epigenetic levels and abnormal cell division.
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Members of the BMP family were originally found to induce bone formation, as their name suggests. However, BMPs are very multifunctional and can also regulate apoptosis, cell migration, cell division, and differentiation. They also specify the anterior/posterior axis, induce growth, and regulate homeostasis. The BMPs bind to the bone morphogenetic protein receptor type II (BMPR2).
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Karcavich, Rachel E. (2005). Generating neuronal diversity in the Drosophila central nervous system: a view from the ganglion mother cells. Developmental Dynamics: An Official Publication Of The American Association Of Anatomists, 232(3), 609-616. At a certain point, a neuroblast will undergo asymmetric cell division giving rise to a neuroblast and a ganglion mother cell.
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The mesosome was thought to increase the surface area of the cell, aiding the cell in cellular respiration. This is analogous to cristae in the mitochondrion in eukaryotic cells, which are finger-like projections and help eukaryotic cells undergo cellular respiration. Mesosomes were also hypothesized to aid in photosynthesis, cell division, DNA replication, and cell compartmentalisation.
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A specialized anatomical structure, called a clamp connection, is formed at each hyphal septum. As with the structurally similar hook in the ascomycetes, the clamp connection in the basidiomycetes is required for controlled transfer of nuclei during cell division, to maintain the dikaryotic stage with two genetically different nuclei in each hyphal compartment.Alexopoulos et al., pp. 492–493.
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The second reason is that haploid cells of one mating type, upon cell division, often produce cells of the opposite mating type with which they may mate. Katz Ezov et al. presented evidence that in natural S. cerevisiae populations clonal reproduction and a type of “self-fertilization” (in the form of intratetrad mating) predominate. Ruderfer et al.
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By 2010, doctors had begun experimental treatments for leukemia patients using CD19-targeted T cells with added DNA to stimulate cell division. As of 2015 trials had treated about 350 leukemia and lymphoma patients. Antigen CD19 appears only on B cells, which go awry in lymphoma and leukemia. Loss of B cells can be countered with immunoglobulin.
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GISTs are tumors of connective tissue, i.e. sarcomas; unlike most gastrointestinal tumors, they are nonepithelial. About 70% occur in the stomach, 20% in the small intestine and less than 10% in the esophagus. Small tumors are generally benign, especially when cell division rate is slow, but large tumors disseminate to the liver, omentum and peritoneal cavity.
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As women (and mice) age, double-strand breaks accumulate in their primordial follicle reserve. These follicles contain primary oocytes that are arrested in prophase of the first cell division of meiosis. Double- strand breaks are accurately repaired during meiosis by searching for, and building off of, the matching strand (termed “homologous recombinational repair”). Titus et al.
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The underlying mechanism involves multiple genetic mutations that results in rapid cell division. The excessive immature lymphocytes in the bone marrow interfere with the production of new red blood cells, white blood cells, and platelets. Diagnosis is typically based on blood tests and bone marrow examination. ALL is typically treated initially with chemotherapy aimed at bringing about remission.
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Caulobacter crescentus is a Gram-negative, oligotrophic bacterium widely distributed in fresh water lakes and streams. The taxon is more properly known as Caulobacter vibrioides (Henrici and Johnson 1935). Caulobacter is an important model organism for studying the regulation of the cell cycle, asymmetric cell division, and cellular differentiation. Caulobacter daughter cells have two very different forms.
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The yeast cohesin complex consists of specialized proteins, including Scc1. Stable cohesion between sister chromatids before anaphase and their timely separation during anaphase are critical for cell division and chromosome inheritance. In vertebrates, sister chromatid cohesion is released in 2 steps via distinct mechanisms. The first step involves phosphorylation of STAG1 or STAG2 in the cohesin complex.
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In mammalian cells, DNA methylation is the primary marker of transcriptionally silenced regions. Specialized proteins can recognize the marker and recruit histone deacetylases and methylases to re-establish the silencing. Nucleosome histone modifications could also be inherited during cell division, however, it is not clear whether it can work independently without the direction by DNA methylation.
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In cell division, two identical clone daughter cells are produced. Some bacteria, while still reproducing asexually, form more complex reproductive structures that help disperse the newly formed daughter cells. Examples include fruiting body formation by Myxobacteria and aerial hyphae formation by Streptomyces, or budding. Budding involves a cell forming a protrusion that breaks away and produces a daughter cell.
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Genes are regulated so that they are expressed only when the product is needed, since expression draws on limited resources. A cell regulates its gene expression depending on its external environment (e.g. available nutrients, temperature and other stresses), its internal environment (e.g. cell division cycle, metabolism, infection status), and its specific role if in a multicellular organism.
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Cell division without enlargement appears to continue beyond what it would in embryos, and without other embryonic traits becoming apparent. Such division is found in a wide range of eukaryotes, including some that are not truly multicellular, and this more conservative interpretation looks to be more parsimonious than embryonic claims. Some have also been interpreted as algal.
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Factors and mechanisms controlling cell differentiation in somatic embryos are relatively ambiguous. Certain compounds excreted by plant tissue cultures and found in culture media have been shown necessary to coordinate cell division and morphological changes.Warren, G.S., Fowler, M.W. 1981. Physiological interactions during the initial stages of embryogenesis in cultures of Daucus carota L. New Phytol 87:481-486.
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Cell division adds to the length produced by convergent extension. Some of the cells from the anterior portion of the epiblast contribute to the formation of Hensen's node. The Hensen's node is the organizer for gastrulation in the vertebrate embryo. Simultaneously, the secondary hypoblast (endoblast) cells continue to migrate anteriorly from the blastoderm's posterior marginal zone.
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The function of centrosome in this context is hypothesized to ensure the fidelity of cell division because it greatly increases the efficacy. Some cell types arrest in the following cell cycle when centrosomes are absent. This is not a universal phenomenon. When the nematode C. elegans egg is fertilized the sperm delivers a pair of centrioles.
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These centrioles will form the centrosomes which will direct the first cell division of the zygote and this will determine its polarity. It's not yet clear whether the role of the centrosome in polarity determination is microtubule dependent or independent. In human reproduction, the sperm supplies the centriole that creates the centrosome and microtubule system of the zygote.
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ADEP antibiotics can be used to defeat resistant bacterial infections. They bind to ClpP and allow the protease to degrade proteins without the help of an ATPase. ADEP4/ClpP complexes target primarily newly formed proteins, and FtsZ which allows cell division. ClpP active form is a tetradecamer composed of two heptamers to which 14 ADEPs bind to.
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Phytopathology 72:336-346. Nematode feeding on floret primordia induces rapid cell division, cell enlargement, and subsequent cell degeneration and collapse. The continuation of this process results in the formation of a large central cavity (in which the now-sedentary nematodes reside) enveloped by a gall wall. Gall size increases rapidly as nematodes grow and reproduce.
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Cell-based models are mathematical models that represent biological cells as a discrete entities. They are used in the field of computational biology for simulating the biomechanics of multicellular structures such as tissues. Their main advantage is the easy integration of cell level processes such as cell division, intracellular processes and single-cell variability within a cell population.
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Very little is known about reproduction in Mallomonas. All that is known is that two vegetative cells fuse to produce a zygote, which then encysts and remains in sediment until germination. Vegetative cell division occurs after excystment. In only minutes cytokinesis occurs, beginning from the anterior end and proceeding down the longitudinal axis of the cell.
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Some peptidoglycan synthesis inhibitors (eg. cefuroxime, ceftazidime) induce filamentation by inhibiting the penicillin binding proteins (PBPs) responsible for crosslinking peptidoglycan at the septal wall (eg. PBP3 in E. coli and P. aeruginosa). Because the PBPs responsible for lateral wall synthesis are relatively unaffected by cefuroxime and ceftazidime, cell elongation proceeds without any cell division and filamentation is observed.
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Cell polarity is a prerequisite for several fundamental operations in animal cells, such as asymmetric cell division and morphogenesis. For both of these, polarization is determined by the same set of proteins, known as PAR proteins. It is not known how these proteins set polarity. The investigators have proposed a dual approach, combining in vitro and cell extract techniques.
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Overview of signal transduction pathways involved in apoptosis. The role of Raf proteins like B-Raf is indicated in the center.B-Raf is a member of the Raf kinase family of growth signal transduction protein kinases. This protein plays a role in regulating the MAP kinase/ERKs signaling pathway, which affects cell division, differentiation, and secretion.
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The drug Tamoxifen is a commonly administered drug used to treat luminal cancers in patients. Half of patients treated with Tamoxifen are resistant to the drug. Overexpression of ZNF703 has been linked to Tamoxifen resistance. As transcription of the ZNF703 gene reaches substantial levels, instead of blocking cell proliferation, Tamoxifen is found to increase cancer cell division.
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Cell division cycle 7-related protein kinase is an enzyme that in humans is encoded by the CDC7 gene. The Cdc7 kinase is involved in regulation of the cell cycle at the point of chromosomal DNA replication. The gene CDC7 appears to be conserved throughout eukaryotic evolution; this means that most eukaryotic cells have the Cdc7 kinase protein.
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Cancer metastasis consists in the fast and uncontrolled division of abnormal cells. Microtubules have a key role in mitosis: they generate the mitotic spindle assembly, which allows chromosome segregation and the cell division. Their stabilization leads to the inability of cells to reproduce or to their apoptosis. That is why microtubule targeting agents are, nowadays, powerful anticancer drugs.
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These chloroplasts are surrounded by three membranes and contain chlorophylls A and B, along with other pigments, so are probably derived from a captured green alga. Reproduction occurs exclusively through cell division. During mitosis, the nuclear membrane remains intact, and the spindle microtubules form inside of it. The group is characterized by the ultrastructure of the flagella.
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In the Gram-negative bacterium Escherichia coli (E. coli), cell division may be partially regulated by AI-2-mediated quorum sensing. This species uses AI-2, which is produced and processed by the lsr operon. Part of it encodes an ABC transporter, which imports AI-2 into the cells during the early stationery (latent) phase of growth.
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Formation of Microtubule The structure of microtubules is long, hollow cylinder dynamically assembled from α/β-tubulin dimers. They play an essential role in maintaining the structure of the cell as well as cell processes, for example, movement of organelles. In addition, microtubule is responsible of forming mitotic spindle in eukaryotic cells to transport chromosomes in cell division.
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If one of these atypical reproductive cells contributes to the genetic makeup of a child, the child will have an extra chromosome 13 in each of the body's cells. Mosaic Patau syndrome is also not inherited. It occurs as a random error during cell division early in fetal development. Patau syndrome due to a translocation can be inherited.
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A gametid is a complementary gamete to the gamete that gives rise to a zygote after conception. During meiosis, four gametes, or haploid cells, are the products of diploid cell division. Two gametes, one egg and one sperm, unite during conception, yielding a zygote. For each gamete that makes a zygote, there is a complementary gamete, or gametid.
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Another MAP whose function has been investigated during cell division is known as XMAP215 (the "X" stands for Xenopus). XMAP215 has generally been linked to microtubule stabilization. During mitosis the dynamic instability of microtubules has been observed to rise approximately tenfold. This is partly due to phosphorylation of XMAP215, which makes catastrophes (rapid depolymerization of microtubules) more likely.
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The toxic enzyme bolesatine has been isolated from fruiting bodies of R. satanas and implicated in the poisonings. Bolesatine is a protein synthesis inhibitor and, when given to mice, causes massive thrombosis. At lower concentrations, bolesatine is a mitogen, inducing cell division in human T lymphocytes. Licastro F, Morini MC, Kretz O, Dirheimer G, Creppy EE; Stirpe F. (1993).
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Citron-K is expressed during neurogenesis and play important roles in neuronal progenitor cell division. Recessive mutations in Citron-K cause severe microcephaly both in rats and mice. In humans and rodents, loss of Citron-K expression results in defects in neurogenic cytokinesis. Similarly in Drosophila, RNAi knockdown of Citron-K results in a failure of cellular abscission.
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In tectiform choanoflagellates, costal strips are accumulated in a set arrangement below the collar. During cell division, the new cell takes these costal strips as part of cytokinesis and assembles its own lorica using only these previously produced strips. Choanoflagellate biosilicification requires the concentration of silicic acid within the cell. This is carried out by Silicon Transporter (SIT) proteins.
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Ecuadorian Jews have achieved prominence in various fields including academics, industry, and science. Benno Weiser ( Benjamin Varon), who was an active Ecuadorian journalist, later entered the Israeli diplomatic service, serving in various Latin American countries. His brother, Max Weiser, was the first Israeli consul in Ecuador. Moselio Schaechter is a researcher involved studying bacterial growth and cell division.
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Many acridone alkaloids are methylated on the nitrogen atom and also have two oxygen functional groups, which can be free, alkylated or incorporated into rings. Acridone alkaloids show a blue-green fluorescence so that they can be detected with UV light. Some alkaloids of this group are effective against malaria pathogens. Furthermore, acronycin inhibits cell division.
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Hertwig's rule or 'long axis rule' states that a cell divides along its long axis. It was introduced by german zoologist Oscar Hertwig in 1884. The rule emphasizes the cell shape to be a default mechanism of spindle apparatus orientation. Hertwig's rule predicts cell division orientation, that is important for tissue architecture, cell fate and morphogenesis.
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It works mostly via podophyllotoxin which stops cell division. Podophyllin resin has been used to treat warts since at least 1820. It is on the World Health Organization's List of Essential Medicines, the safest and most effective medicines needed in a health system. In the United States a course of treatment costs about 50 to US$100.
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One of the metabolites, stypoldione, has been shown to inhibit cell division in sea urchin eggs and another exhibits cytotoxic activity against human lung and colon carcinoma cells. In another study it was found that some of the metabolites were present across the whole of the seaweed's range but others were found only in localised populations.
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The principal mechanism of the epothilone class is inhibition of microtubule function. Microtubules are essential to cell division, and epothilones therefore stop cells from properly dividing. Epothilone B possess the same biological effects as paclitaxel both in vitro and in cultured cells. This is because they share the same binding site, as well as binding affinity to the microtubule.
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The reproductive cycle of red algae may be triggered by factors such as day length. Red algae reproduce sexually as well as asexually. Asexual reproduction can occur through the production of spores and by vegetative means (fragmentation, cell division or propagules production). In Archibald, J. M., In Simpson, A. G. B., & In Slamovits, C. H. (2017).
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One way simply measures the amount of the different DNA sequences along the length of the chromosome per cell. Sequences that duplicate first, long before cell division, will be more abundant in each cell than the sequences that replicate last just prior to cell division. The other way is to label newly synthesized DNA with chemically tagged nucleotides that become incorporated into the strands as they are synthesized, and then catch cells at different times during the duplication process and purify the DNA synthesized at each of these times using the chemical tag. In either case, we can measure the amount of the different DNA sequences along the length of the chromosome either directly using a machine that reads how much of each sequence is present or indirectly using a process called microarray hybridization.
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She is recognized as a leader in the study of cell polarity in the context of morphogenesis and asymmetric cell division, and has been at the forefront of using mathematical and biophysical approaches to understand cell polarity as a self-organizing, dynamical system. This advancement of quantitative and predictive understanding of cellular behavior relates to health, to learning and to human individuality, especially her research on topics such as cell polarity, asymmetric cell division, polycystic kidney disease, and adaptive evolution. Li was also one of the first to demonstrate the critical in vivo role for the Arp2/3 complex and WASP family proteins in the control of actin filament assembly, and to show through in vitro biochemistry that the Arp2/3 complex is an actin nucleator activated by WASP family members. In collaboration with Drs.
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General stages of cell lineage (cell lineage of liver development in red) Cell lineage denotes the developmental history of a tissue or organ from the fertilized embryo. This is based on the tracking of an organism's cellular ancestry due to the cell divisions and relocation as time progresses, this starts with the originator cells and finishing with a mature cell that can no longer divide. This type of lineage can be studied by marking a cell (with fluorescent molecules or other traceable markers) and following its progeny after cell division. Some organisms, such as C. elegans, have a predetermined pattern of cell progeny and the adult male will always consist of 1031 cells, this is because cell division in C. elegans is genetically determined and known as eutely.
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Particularly hard-hit by heavy water are the delicate assemblies of mitotic spindle formations necessary for cell division in eukaryotes. Plants stop growing and seeds do not germinate when given only heavy water, because heavy water stops eukaryotic cell division. The deuterium cell is larger and is a modification of the direction of division.Crespi, H., Conrad, S., Uphaus, R., Katz, J. (1960) Cultivation of Microorganisms in Heavy Water, Annals of the New York Academy of Sciences, Deuterium Isotopes in Chemistry and Biology, pp. 648–666.Mosin, O. V., I. Ignatov, I. (2013) Microbiological Synthesis of 2H-Labeled Phenylalanine, Alanine, Valine, and Leucine/Isoleucine with Different Degrees of Deuterium Enrichment by the Gram- Positive Facultative Methylotrophic Bacterium Вrevibacterium Methylicum, International Journal of Biomedicine Vol. 3, N 2, pp. 132–138.
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When a cell prepares to divide, a complete new set-up of DNA is required, and the requirement for building blocks, including thymidine triphosphate, increases. Cells prepare for cell division by making some of the enzymes required during the division. They are not normally present in the cells and are downregulated and degraded afterwards. Such enzymes are called salvage enzymes.
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Progeria is caused by mutations that weaken the structure of the cell nucleus, making normal cell division difficult. The histone mark H4K20me3 is involved in Hutchinson-Gilford Progeria syndrome caused by de novo mutations that occurs in a gene that encodes lamin A. Lamin A is made but isn't processed properly. This poor processing creates an abnormal nuclear morphology and disorganized heterochromatin.
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Theoretically, these cells are not germ cells (the source of gametes); they transmit their mutations, to their cellular descendants (if they have any), but not to the organism's descendants. However, in sponges, non-differentiated somatic cells form the germ line and, in Cnidaria, differentiated somatic cells are the source of the germline. Mitotic cell division is only seen in diploid somatic cells.
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Acentric fragments are commonly generated by chromosome-breaking events, such as irradiation. Such acentric fragments are unequally distributed between the daughter cells after cell division. Acentric fragments can also be produced when an inverted segment is present in one member of a chromosome pair. In that case, a crossover event will result in one chromosome with two centromeres and an acentric fragment.
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Telomerase restores short bits of DNA known as telomeres, which are otherwise shortened when a cell divides via mitosis. In normal circumstances, where telomerase is absent, if a cell divides recursively, at some point the progeny reach their Hayflick limit, which is believed to be between 50–70 cell divisions. At the limit the cells become senescent and cell division stops.Siegel, L (2013).
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Werner syndrome ATP-dependent helicase, also known as DNA helicase, RecQ-like type 3, is an enzyme that in humans is encoded by the WRN gene. WRN is a member of the RecQ Helicase family. Helicase enzymes generally unwind and separate double-stranded DNA. These activities are necessary before DNA can be copied in preparation for cell division (DNA replication).
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Michael Botchan is a professor of biochemistry and molecular biology at the University of California, Berkeley, where his research focuses on regulation of DNA replication during cell division. Botchan is a member of the United States National Academy of Sciences and the American Academy of Arts and Sciences and was appointed as the dean of the university's Division of Biological Sciences in 2017.
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This protein family entry consists of several bacterial zeta toxin proteins. Zeta toxin is thought to be part of a postsegregational killing (PSK) system involved in the killing of plasmid-free cells. It relies on antitoxin/toxin systems that secure stable inheritance of low and medium copy number plasmids during cell division and kill cells that have lost the plasmid.
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In developmental biology, midblastula or midblastula transition (MBT) occurs during the blastula stage of embryonic development. During this stage, the embryo is referred to as a blastula. The series of changes to the blastula that characterize the midblastula transition include activation of zygotic gene transcription, slowing of the cell cycle, increased asynchrony in cell division, and an increase in cell motility.
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In insects, they are commonly found in the salivary glands when the cells are not dividing. They are produced when repeated rounds of DNA replication without cell division forms a giant chromosome. Thus polytene chromosomes form when multiple rounds of replication produce many sister chromatids which stay fused together. Polytene chromosomes, at interphase, are seen to have distinct thick and thin banding patterns.
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Neuroepithelial cells symmetrically divide or differentiate into progenitor cells called radial glial cells in asymmetric cell division. These can further differentiate into neurons or glial cells. Neuroepithelial cells are a class of stem cell and have the ability to self-renew. During the formation of the neural tube, neuroepithelial cells undergo symmetric proliferative divisions that give rise to two new neuroepithelial cells.
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In adult Drosophila, each proprioceptor class arises from a specific cell lineage (i.e. each chordotonal neuron is from the chordotonal neuron lineage, although multiple lineages give rise to sensory bristles). After the last cell division, proprioceptors send out axons toward the central nervous system and are guided by hormonal gradients to reach stereotyped synapses. Jan, Y. N. and Jan, L. Y. (1993).
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One basic mechanism that can produce mosaic tissue is mitotic recombination or somatic crossover. It was first discovered by Curt Stern in Drosophila in 1936. The amount of tissue that is mosaic depends on where in the tree of cell division the exchange takes place. A phenotypic character called "twin spot" seen in Drosophila is a result of mitotic recombination.
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Instead, they prevent other mutations from surviving for example by slowing the cell division process to enable DNA repair to complete, or by initiating apoptosis of the cell. In genetic knock-out and rescue experiments, restoration of a caretaker gene from the mutated form to the wildtype version does not limit tumorigenesis.Hainut, P. 2005. ‘‘25 years of p53 research.’’ New York: Springer Publishing.
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It also helps transport cargo needed for cell function such as vesicles made by the endoplasmic reticulum, endosomes, and lysosomes (Karp, 2005). Dynein is involved in the movement of chromosomes and positioning the mitotic spindles for cell division. Dynein carries organelles, vesicles and possibly microtubule fragments along the axons of neurons toward the cell body in a process called retrograde axoplasmic transport.
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Other examples are dinophyta and diatoms that have a cell wall that does not change during the cell cycle. During cell-growth, when the amounts of protein and carbohydrates increase, the vacuole shrinks. The outer membrane that is involved in nutrient uptake remains constant. At cell division, the daughter cells rapidly take up water, complete a new cell wall and the cycle repeats.
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Historically, karyotypes have been obtained by staining cells after they have been chemically arrested during cell division. Karyotypes have been used for several decades to identify chromosomal abnormalities in both germline and cancer cells. Conventional karyotypes can assess the entire genome for changes in chromosome structure and number, but the resolution is relatively coarse, with a detection limit of 5-10Mb. Fig 1.
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In either case, expression of these genes promotes the malignant phenotype of cancer cells. Tumor suppressor genes are genes that inhibit cell division, survival, or other properties of cancer cells. Tumor suppressor genes are often disabled by cancer-promoting genetic changes. Finally Oncovirinae, viruses that contain an oncogene, are categorized as oncogenic because they trigger the growth of tumorous tissues in the host.
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Problems in male meiosis resulting in a male gamete with 2 X-chromosomes. Problems in female meiosis resulting in a female gamete with 2 X-chromosomes. Triple X syndrome is not inherited, but usually occurs as an event during the formation of reproductive cells (ovum and sperm). An error in cell division called nondisjunction can result in reproductive cells with additional chromosomes.
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They are absolutely required for correct positioning and orientation of the mitotic spindle apparatus, and are thus involved in determining the cell division site based on the geometry and polarity of the cells. The maintenance of astral microtubules is dependent on the integrity of centrosome. It is also dependent on several microtubule-associated proteins such as EB1 and adenomatous polyposis coli (APC).
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The second-stage juvenile, or J2, nematode is the only life stage that can penetrate roots. (The first-stage juvenile occurs in the egg, and third- and fourth-stages occur in the roots). The J2 enters the root moving through the plant cells to the vascular tissue where it feeds. The J2 induces cell division in the root to form specialized feeding sites.
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This family includes TGF-β1, TGF-β2, TGF-β3, and TGF-β5. They are involved in positively and negatively regulation of cell division, the formation of the extracellular matrix between cells, apoptosis, and embryogenesis. They bind to TGF-β type II receptor (TGFBRII). TGF-β1 stimulates the synthesis of collagen and fibronectin and inhibits the degradation of the extracellular matrix.
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Phosphatidylinositol glycan anchor biosynthesis class U protein is a protein that in humans is encoded by the PIGU gene. The protein encoded by this gene shares similarity with Saccharomyces cerevisiae Cdc91, a predicted integral membrane protein that may function in cell division control. The protein encoded by this gene is the fifth subunit of GPI transamidase that attaches GPI-anchors to proteins.
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This will become a microsphere. Due to metabolic reaction, osmotic pressure will build up inside the microsphere, and this will generate a force for invaginating the membrane, and ultimately division. In fact, this is close to the cell division of cell wall-less bacteria, such as Mycoplasma. Continuous reactions will also invariably produce variable polymers that can be inherited by daughter cells.
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Mature macrophages do not travel far but stand guard over those areas of the body that are exposed to the outside world. There they act as garbage collectors, antigen presenting cells, or ferocious killers, depending on the signals they receive. They derive from monocytes, granulocyte stem cells, or the cell division of pre-existing macrophages. Human macrophages are about 21 micrometers in diameter.
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Meiosis occurs and a megaspore is produced as the first cell of the megagametophyte. As cell division takes place the nucleus of the megaspore thickens, and cell differentiation occurs to produce prothallial tissue containing an ovum. The remaining undifferentiated cells then form the endosperm. When the male structure releases its pollen grains, some fall onto the female strobilus and reach the ovule.
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Hayflick first became suspicious of Carrel's claims while working in a lab at the Wistar Institute. Hayflick noticed that one of his cultures of embryonic human fibroblasts had developed an unusual appearance and that cell division had slowed. Initially, he brushed this aside as an anomaly caused by contamination or technical error. However, he later observed other cell cultures exhibiting similar manifestations.
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The SOS system has enhanced DNA-repair capacity, including excision and post-replication repair, enhanced mutagenesis, prophage induction. The system can also inhibit cell division and cell respiration. bacterial evolution of certain types of antibiotic resistance. The SOS response is a global response to DNA damage in which the cell cycle is arrested and DNA repair and mutagenesis is induced.
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Indirubin exerts its effects on the human body by downregulating expression of genes. Genes PLK1 and PIN1, both oncogenic, have been shown to be affected by indirubin. Indirubin has, in vitro and in vivo, been shown to reduce expression of the CDC25B gene, which codes for production of CDC25B enzyme. CDC stands for cell-division-cycle, and is used in cellular reproduction.
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Telolecithal (Greek: τέλος (telos) = end, λέκιθος (lekithos) = yolk), refers to the uneven distribution of yolk in the cytoplasm of ovums found in birds, reptiles, fish, and monotremes. The yolk is concentrated at one pole of the egg separate from the developing embryo. This type of egg undergoes discoidal meroblastic cleavage, where yolk is not incorporated in the cells during cell division.
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TipN has two transmembrane regions in the N-terminal region and a large C-terminal coiled-coil domain. TipN homologues are present in other alpha-proteobacteria. TipN localizes to the new pole in both daughter cells after division and relocalizes to the cell division site in the late predivisional cell. Therefore, both daughter cells have TipN at the new pole after division.
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Helobdella triserialis), the provisional epithelium covering the cells plays a role in inducing the O fate. In the absence of cell-cell interactions, the O/P precursors will become O teloblasts. O and P bandlets exhibit very different mitotic patterns (see figure) which are used to identify them in experimental manipulations. O and P teloblasts have very different cell division patterns.
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During cell division, a cell will make copies of its DNA. The enzymes in the cell that are responsible for copying the DNA cannot copy the very ends of the chromosomes. This is sometimes called the "end replication problem". If a cell did not contain telomeres, genetic information from the DNA on the ends of chromosomes would be lost with each division.
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Cyclins are a group of proteins that activate kinases involved in cell division. The degradation of cyclins is the key step that governs the exit from mitosis and progress into the next cell cycle. Cyclins accumulate in the course the cell cycle, then abruptly disappear just before the anaphase of mitosis. The cyclins are removed via a ubiquitin-mediated proteolytic pathway.
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The protein, Shugoshin, is actually Japanese for guardian spirit. Just as its name suggests, the Shugoshin protein guides chromosome cohesion during cell division. It does this by preventing the cohesin complex which regulates chromatid separation from prematurely dissociating. Shugoshin protein is thought to act by protecting two proteins, named Rec8 and Rad21 at the centromeres from protein degradation by the enzyme, separase.
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The telomere prevents the chromosomes from fusing. Most cells turn off telomerase, restricting their proliferation, whilst cancer cells activate telomerase and encourage cell division. In 2018 Collins reported the most detailed image of the three-dimensional molecular structure of telemorase, which offered hope for the design of drugs that can prevent cancer and ageing. Collins developed a scalpel-free approach to tumour biopsies.
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The mitotic phase is a relatively short period of the cell cycle. It alternates with the much longer interphase, where the cell prepares itself for the process of cell division. Interphase is divided into three phases: G1 (first gap), S (synthesis), and G2 (second gap). During all three parts of interphase, the cell grows by producing proteins and cytoplasmic organelles.
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In 1925, they discovered a corn plant had three complete sets of chromosomes (meaning it was a triploid). They also studied the meiotic (cell division) behaviour of the chromosomes in the pollen of the corn. The results of the study were published in 1926.Esra Galun L.F. Randolph and B. McClintock 1926, 'Polyploidy in Zea mays' L. in American Naturalist, Vol.
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It is possible for errors to occur during this process of repetitive cell division. Common among these errors is for the genetic material to not be divided evenly. Normally, when a cell divides each daughter cell has the same genetic material as the parent cell. If the genetic material does not split evenly between the two daughter cells, an event called "nondisjunction" occurs.
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The PCM is essential for nucleation and organization of microtubules. The centrosome cycle is important to ensure that daughter cells receive a centrosome after cell division. As the cell cycle progresses, the centrosome undergoes a series of morphological and functional changes. Initiation of the centrosome cycle occurs early in the cell cycle in order to have two centrosomes by the time mitosis occurs.
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Some cancer cells also have abnormal numbers of chromosomes. About 68% of human solid tumors are aneuploid. Aneuploidy originates during cell division when the chromosomes do not separate properly between the two cells (nondisjunction). Most cases of aneuploidy in the germline result in miscarriage, and the most common extra autosomal chromosomes among live births are X, Y, 21, 18 and 13.
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Polydendrocytes can undergo cell division while maintaining synaptic inputs from neurons. These observations suggest that cells that receive neuronal synaptic inputs and those that differentiate into oligodendrocytes are not mutually exclusive cell populations but that the same population of polydendrocytes can receive synaptic inputs and generate myelinating oligodendrocytes. The functional significance of the neuron-polydendrocyte synapses remains to be elucidated.
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After that, E. coli cells with only 15N in their DNA were transferred to a 14N medium and were allowed to divide; the progress of cell division was monitored by microscopic cell counts and by colony assay. DNA was extracted periodically and was compared to pure 14N DNA and 15N DNA. After one replication, the DNA was found to have intermediate density.
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The latter phase has been modelled using the ABC model, which describes the biological basis of the process from the perspective of molecular and developmental genetics. An external stimulus is required in order to trigger the differentiation of the meristem into a flower meristem. This stimulus will activate mitotic cell division in the meristem, particularly on its sides where new primordia are formed.
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In 1998, he won the Albert Lasker Award for Basic Medical Research with Lee Hartwell and Paul Nurse for their pioneering work on cell division. He was elected a Fellow of the Royal Society (FRS) in 1998 and an officer of the Order of Canada in 2003 in recognition of his life's work. in 1992 he was awarded the Gairdner Foundation International Award.
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Photosynthesis is essential for the production of domoic acid. Periods of darkness or chemical inhibition of photosynthesis has been shown to inhibit toxin production. Additionally, DA production peaks in the stationary phase of the growth cycle when cell division is slowed or absent. Production is minimal or nonexistent during the exponential phase, and ceases completely during the death phase of the growth cycle.
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Trisha Nell Davis (born May 27, 1954) is an American biochemist, the current Earl Davie/ZymoGenetics Chair of the Department of Biochemistry at the University of Washington.. Her early research focused on Calmodulin, though the primary focus of her lab has since shifted to the molecular machinery of cell division in budding yeast, especially the microtubule organizing centers and the kinetochores.
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When LIS1 is deleted, lissencephaly occurs. LIS1 is thought to have several important roles in the creation of the cortex. Since LIS1 is similar to the nuclear distribution protein F (nudF), they are thought to work similarly. The nud family is known to be a factor in nuclear translocation, or moving the nuclei of daughter cells after cell division has occurred.
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Several lines of evidence indicate lifestyle-induced hyperinsulinemia and reduced insulin function (i.e. insulin resistance) as decisive factors in many disease states. For example, hyperinsulinemia and insulin resistance are strongly linked to chronic inflammation, which in turn is strongly linked to a variety of adverse developments such as arterial microinjuries and clot formation (i.e. heart disease) and exaggerated cell division (i.e. cancer).
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Telomere shortening in humans can induce replicative senescence, which blocks cell division. This mechanism appears to prevent genomic instability and development of cancer in human aged cells by limiting the number of cell divisions. However, shortened telomeres impair immune function that might also increase cancer susceptibility. If telomeres become too short, they have the potential to unfold from their presumed closed structure.
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FtsZ was the first protein of the prokaryotic cytoskeleton to be identified. Like tubulin, FtsZ forms filaments in the presence of guanosine triphosphate (GTP), but these filaments do not group into tubules. During cell division, FtsZ is the first protein to move to the division site, and is essential for recruiting other proteins that synthesize the new cell wall between the dividing cells.
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Cell surface heparan sulfate proteoglycans are composed of a membrane-associated protein core substituted with a variable number of heparan sulfate chains. Members of the glypican-related integral membrane proteoglycan family (GRIPS) contain a core protein anchored to the cytoplasmic membrane via a glycosyl phosphatidylinositol linkage. These proteins may play a role in the control of cell division and growth regulation.
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The unsporulated oocyst is shed from an infected bird in the feces. This exposure to air and moisture triggers meiosis and cell division. After 9–12 hours of sporulation (asexual reproduction by the production and release of spores) eight haploid sporozoites are formed. It has completed the sporulation stage after about 24 hours and can now infect a new host.
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Children with RSS that are treated with growth hormone before puberty may achieve several inches of additional height. In January 2008, it was published that mutations in the pericentrin gene (PCNT) were found to cause primordial dwarfism. Pericentrin has a role in cell division, proper chromosome segregation and cytokinesis. Another gene that has been implicated in this condition is DNA2.
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Podophyllotoxin possesses a large number of medical applications, as it is able to stop replication of both cellular and viral DNA by binding necessary enzymes. It can additionally destabilize microtubules and prevent cell division. Because of these interactions it is considered an antimitotic drug. Podophyllotoxin and its derivatives are used as cathartic, purgative, antiviral agent, vesicant, antihelminthic, and antitumor agents.
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Kinesin-like protein KIF22 is a protein that in humans is encoded by the KIF22 gene. The protein encoded by this gene is a member of kinesin-like protein family. This family of proteins are microtubule-dependent molecular motors that transport organelles within cells and move chromosomes during cell division. The C-terminal half of this protein has been shown to bind DNA.
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When a cell prepares to divide, a complete new set-up of DNA is required, and the requirement for building blocks, including thymidine triphosphate, increases. Cells prepare for cell division by making some of the enzymes required during the division. They are not normally present in the cells and are down- regulated and degraded afterwards. Such enzymes are called salvage enzymes.
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The ability of anillin to bind to and bundle actin together is conversed through many species. It is hypothesized that by regulating actin bundling, anillin increases the efficiency of actomyosin contractility during cell division. Both anillin and F-actin are found in contractile structures. They are recruited independently to the contractile ring, but F-actin increases the efficiency of anillin targeting.
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Véraison in Chateauneuf du Pape Grape berries follow a double sigmoid growth curve. The initial phase of berry growth is a result of cell division and cell expansion. As berry growth of phase I slows this is termed the lag phase. The lag phase is not a physiological growth stage, but an artificial designation between the two growth periods of grape berry development.
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Wente and her colleagues discuss the overall function of the nuclear pore complex (NPC). They discuss that NPCs are the only known means of exchange for materials between the nucleus and cytoplasm. They discuss the different types of nucleus to cytoplasm transport. They conclude that proper NPC development is essential for physiological functioning, which if damaged, could cause improper cell division.
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The structure of paclitaxel, a widely used mitotic inhibitor. A mitotic inhibitor is a drug that inhibits mitosis, or cell division. These drugs disrupt microtubules, which are structures that pull the chromosomes apart when a cell divides. Mitotic inhibitors are used in cancer treatment, because cancer cells are able to grow and eventually spread through the body (metastasize) through continuous mitotic division.
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This interrupts cell division, usually during the mitosis (M) phase of the cell cycle when two sets of fully formed chromosomes are supposed to separate into daughter cells. Examples of mitotic inhibitors frequently used in the treatment of cancer include paclitaxel, docetaxel, vinblastine, vincristine, and vinorelbine. Colchicine and griseofulvin are mitotic inhibitors used in the treatment of gout and toenail fungus, respectively.
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Chemotherapy is the treatment of cancer with drugs ("anticancer drugs") that can destroy cancer cells. In current usage, the term "chemotherapy" usually refers to cytotoxic drugs which affect rapidly dividing cells in general, in contrast with targeted therapy (see below). Chemotherapy drugs interfere with cell division in various possible ways, e.g. with the duplication of DNA or the separation of newly formed chromosomes.
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23 pairs of chromosomes). Human gametes have only 23 chromosomes. If the chromosome pairs fail to separate properly during cell division, the egg or sperm may end up with a second copy of one of the chromosomes. (See non-disjunction.) If such a gamete results in fertilization and an embryo, the resulting embryo may also have an entire copy of the extra chromosome.
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In newt and general amphibian embryos, cell division is not a driving role in morphogenesis. Newt embryo cells are much larger and exhibit egg pigmentation to distinguish cells from each other. The newt neural plate doubles in length, decreases in apical width, and increases in thickness. The plate edges rise dorsally and fold toward the midline to form the neural tube.
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Around the sites of these collisions chemical bonds are broken, creating short lived radicals (e.g. the hydroxyl radical, the hydrogen atom and solvated electrons). These radicals cause further chemical changes by bonding with and or stripping particles from nearby molecules. When collisions occur in cells, cell division is often suppressed, halting or slowing the processes that cause the food to mature.
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Root growth occurs by division of stem cells in the root meristem located in the tip of the root, and the subsequent asymmetric expansion of cells in a shoot-ward region to the tip known as the elongation zone. Differential growth during tropisms mainly involves changes in cell expansion versus changes in cell division, although a role for cell division in tropic growth has not been formally ruled out. Gravity is sensed in the root tip and this information must then be relayed to the elongation zone so as to maintain growth direction and mount effective growth responses to changes in orientation to and continue to grow its roots in the same direction as gravity. Abundant evidence demonstrates that roots bend in response to gravity due to a regulated movement of the plant hormone auxin known as polar auxin transport.
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Floxuridine is a pyrimidine analog that acts as an inhibitor of the S-phase of cell division. This selectively kills rapidly dividing cells. Antimetabolites masquerade as pyrimidine-like molecules which prevents normal pyrimidines from being incorporated into DNA during the S phase of the cell cycle. Fluorouracil (the end-product of catabolism of floxuridine) blocks an enzyme which converts cytosine nucleosides into the deoxy derivative.
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Besides providing mechanical support, the nuclear lamina regulates important cellular events such as DNA replication and cell division. Additionally, it participates in chromatin organization and it anchors the nuclear pore complexes embedded in the nuclear envelope. The nuclear lamina is associated with the inner face of the double bilayer nuclear envelope, whereas the outer face is continuous with the endoplasmic reticulum.The Cell: A Molecular Approach, Cooper & Hausman.
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The next sequence of events varies, depending on the particular species, but in most species, the following events occur. The megasporocyte undergoes a meiotic cell division, producing four haploid megaspores. Only one of the four resulting megaspores survives. This megaspore undergoes three rounds of mitotic division, resulting in seven cells with eight haploid nuclei (the central cell has two nuclei, called the polar nuclei).
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The cartilage model will grow in length by continuous cell division of chondrocytes, which is accompanied by further secretion of extracellular matrix. This is called interstitial growth. The process of appositional growth occurs when the cartilage model also grows in thickness due to the addition of more extracellular matrix on the peripheral cartilage surface, which is accompanied by new chondroblasts that develop from the perichondrium.
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Because cytokinin promotes plant cell division and growth, produce farmers use it to increase crops. One study found that applying cytokinin to cotton seedlings led to a 5–10% yield increase under drought conditions. Cytokinins have recently been found to play a role in plant pathogenesis. For example, cytokinins have been described to induce resistance against Pseudomonas syringae in Arabidopsis thaliana and Nicotiana tabacum.
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Flowering plants generate gametes using a specialized cell division called meiosis. Meiosis takes place in the ovule (a structure within the ovary that is located within the pistil at the center of the flower) (see diagram labeled "Angiosperm lifecycle"). A diploid cell (megaspore mother cell) in the ovule undergoes meiosis (involving two successive cell divisions) to produce four cells (megaspores) with haploid nuclei.Snustad DP, Simmons MJ (2008).
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Budding yeast cytokinesis is driven through two septin dependent, redundant processes: recruitment and contraction of the actomyosin ring and formation of the septum by vesicle fusion with the plasma membrane. In contrast to septin mutants, disruption of one single pathway only leads to a delay in cytokinesis, not complete failure of cell division. Hence, the septins are predicted to act at the most upstream level of cytokinesis.
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Under the genetic code, RNA strands are translated to specify the sequence of amino acids within proteins. These RNA strands are initially created using DNA strands as a template in a process called transcription. Within cells, DNA is organized into long structures called chromosomes. During cell division these chromosomes are duplicated in the process of DNA replication, providing each cell its own complete set of chromosomes.
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While haploid organisms have only one copy of each chromosome, most animals and many plants are diploid, containing two of each chromosome and thus two copies of every gene. The two alleles for a gene are located on identical loci of the two homologous chromosomes, each allele inherited from a different parent. Walther Flemming's 1882 diagram of eukaryotic cell division. Chromosomes are copied, condensed, and organized.
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It is classified as a purine analog, which is a type of antimetabolite. It mimics the nucleoside adenosine and thus inhibits the enzyme adenosine deaminase, interfering with the cell's ability to process DNA. Cancer cells generally divide more often than healthy cells; DNA is highly involved in cell division (mitosis) and drugs which target DNA-related processes are therefore more toxic to cancer cells than healthy cells.
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Developmental pluripotency-associated protein 3 is a protein that in humans is encoded by the DPPA3 gene. This gene encodes a protein that in mice may function as a maternal factor during the preimplantation stage of development. In mice, this gene may play a role in transcriptional repression, cell division, and maintenance of cell pluripotentiality. In humans, related intronless loci are located on chromosomes 14 and X.
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Protein pelota homolog is a protein that in humans is encoded by the PELO gene. This gene encodes a protein which contains a conserved nuclear localization signal. The encoded protein may have a role in spermatogenesis, cell cycle control, and in meiotic cell division. In yeasts, the Dom34-Hbs1 complex (with ABCE1) that it forms is responsible for reactivating ribosomes and for recovering those stuck on mRNAs.
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Anaphase lag is a consequence of an event during cell division where sister chromatids do not properly separate from each other because of improper spindle formation. The chromosome or chromatid does not properly migrate during anaphase and the daughter cells will lose some genetic information. It is one of many causes of aneuploidy. This event can occur during both meiosis and mitosis with unique repercussions.
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This reprogramming does not always require cell division. The cells resulting from such reprogramming are more suitable for cell therapy because they do not form teratomas. For example, Chandrakanthan et al., & Pimanda describe the generation of tissue-regenerative multipotent stem cells (iMS cells) by treating mature bone and fat cells transiently with a growth factor (platelet- derived growth factor–AB (PDGF-AB)) and 5-Azacytidine.
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Mohammadi et al. (2011) showed that the integral membrane protein FtsW (TC# 2.A.103.1.1,4-7), an essential protein for cell division, is a transporter of the lipid-linked peptidoglycan precursors across the cytoplasmic membrane. Using E. coli membrane vesicles, they found that transport of Lipid II requires the presence of FtsW, and purified FtsW induced the transbilayer movement of Lipid II in model membranes.
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Cartoon of the dividing epithelium cell surrounded by epithelium tissue. Spindle apparatus rotates inside the cell. The rotation is a result of astral microtubules pulling towards tri-cellular-junctions (TCJ), signaling centers localized at the regions where three cells meet. More than a century ago Oskar Hertwig proposed that the cell division orientation is determined by the shape of the cell (1884), known as Hertwig rule.
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Echinostelium is a genus of slime mould, and the only genus in the family Echinosteliaceae, or Echinosteliidae. It was discovered by Heinrich Anton de Bary in 1855, apparently near Frankfurt am Main. Some species of Echinostelium have a sexual life cycle; others have been shown to be asexual. The plasmodium can divide vegetatively, in a process called plasmotomy, to distinguish it from true cell division.
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The cytotoxic antibiotics are a varied group of drugs that have various mechanisms of action. The common theme that they share in their chemotherapy indication is that they interrupt cell division. The most important subgroup is the anthracyclines and the bleomycins; other prominent examples include mitomycin C and actinomycin. Among the anthracyclines, doxorubicin and daunorubicin were the first, and were obtained from the bacterium Streptomyces peucetius.
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There are several causes of Beau's lines. It is believed that there is a temporary cessation of cell division in the nail matrix. This may be caused by an infection or problem in the nail fold, where the nail begins to form, or it may be caused by an injury to that area. Some other reasons for these lines include trauma, coronary occlusion, hypocalcaemia, and skin disease.
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M-phase inducer phosphatase 3 is an enzyme that in humans is encoded by the CDC25C gene. This gene is highly conserved during evolution and it plays a key role in the regulation of cell division. The encoded protein is a tyrosine phosphatase and belongs to the Cdc25 phosphatase family. It directs dephosphorylation of cyclin B-bound CDC2 (CDK1) and triggers entry into mitosis.
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Polyploidy is a class of mutation that results in a mitotic doubling and failure in cell division. It appears that this is very common in plants, in the method of unreduced pollen. Polyploidy is more common in the perennial species and species with self-compatibility. The genus as a whole is vastly widespread and has a wide range of ploidy located in almost every continent.
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Histone deacetylase (HDAC) inhibitors, such as vorinostat, have shown some promise in epithelioid sarcoma. Researchers in Texas are investigating whether or not HDAC inhibitors can reverse the loss of INI1 function that is characteristic of epithelioid sarcoma. HDAC inhibitors work by blocking events involved in DNA replication and, therefore, in cell division. Blocking HDAC has been shown to encourage cancer cells to enter apoptosis.
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The young typically reach sexual maturity in about three days. In the laboratory, Lepidodermella squamatum has lived for up to forty days, producing four or five eggs during the first ten days of life. Gastrotrichs demonstrate eutely, each species having an invariant genetically fixed number of cells as adults. Cell division ceases at the end of embryonic development and further growth is solely due to cell enlargement.
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It labels all individual chromosomes at every stage of cell division to display structural and numerical abnormalities that may arise throughout the cycle. This is done with a probe that can be locus specific, centromeric, telomeric, and whole-chromosomal. This technique is typically preformed on interphase cells and paraffin block tissues. FISH maps out single copy or repetitive DNA sequences through localization labeling of specific nucleic acids.
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Many insects, such as the model organism Drosophila melanogaster, lay eggs that initially develop as "syncytial" blastoderms, i.e. early on the embryos exhibit incomplete cell division. The nuclei undergo S-phase (DNA replication) and sister chromatids get pulled apart and re-assembled into nuclei containing full sets of homologous chromosomes, but cytokinesis does not occur. Thus, the nuclei multiply in a common cytoplasmic space.
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Protostomes and deuterostomes differ in several ways. Early in development, deuterostome embryos undergo radial cleavage during cell division, while many protostomes (the Spiralia) undergo spiral cleavage. Animals from both groups possess a complete digestive tract, but in protostomes the first opening of the embryonic gut develops into the mouth, and the anus forms secondarily. In deuterostomes, the anus forms first while the mouth develops secondarily.
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Proper biorientation allows correct chromosomal segregation in cell division. Although this process is not well understood, high- resolution imaging of live mouse oocytes has revealed that chromosomes form an intermediate chromosomal configuration, called the prometaphase belt, which occurs prior to biorientation. Kitajima, et al. estimate that about 90% of chromosomes require correction of the kinetochore-microtubule attachments (using Aurora kinase )prior to obtaining correct biorientation.
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The DNA damage response (DDR) machinery plays an important role in spermatogenesis. The protein FMRP binds to meiotic chromosomes and regulates the dynamics of the DDR machinery during spermatogenesis. FMRP appears to be necessary for the repair of DNA damage. Each cell division from a spermatogonium to a spermatid is incomplete; the cells remain connected to one another by bridges of cytoplasm to allow synchronous development.
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Tetraselmis species have proven to be useful for both research and industry. Tetraselmis species have been studied for understanding plankton growth rates, and recently a colonial colony species is being used to gain an understanding of multicellularity evolution.Arora, M., Anil, A.C., Burgess, K., Delany, J. and Mesbahi, E. 2015: Asymmetric cell division and its role in cell fate determination in the green alga Tetraselmis indica. J. Biosci.
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Another example related to aging is the Telomere theory. Telomere theory proposes that telomeres shorten with repeated cell division which attribute to cell senescence and tissue damage. The end replication problem explains the mechanism behind the inability of DNA polymerase to commence the RNA primer to perform its function in completing the lagging strand due to the shortening of DNA. Telomere shortening is common in somatic cells.
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Kim Ashley Nasmyth (born 18 October 1952) is an English geneticist, the Whitley Professor of Biochemistry at the University of Oxford, a Fellow of Trinity College, Oxford, former scientific director of the Research Institute of Molecular Pathology (IMP), and former head of the Department of Biochemistry, University of Oxford. He is best known for his work on the segregation of chromosomes during cell division.
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Cell reproduction is asexual. For most of the constituents of the cell, growth is a steady, continuous process, interrupted only briefly at M phase when the nucleus and then the cell divide in two. The process of cell division, called cell cycle, has four major parts called phases. The first part, called G1 phase is marked by synthesis of various enzymes that are required for DNA replication.
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Cell wall and middle lamella (top) The middle lamella is a layer which cements the cell walls of two adjoining plant cells together. It is the first formed layer which is deposited at the time of cytokinesis. The cell plate that is formed during cell division itself develops into middle lamella or lamellum. The middle lamella is made up of calcium and magnesium pectates.
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Eating seafood contaminated with lead and cadmium puts people at risk for poisoning. Beads also can get tangled in trees during parades. Here, the lead in the beads can get washed off via rain water and find its way into leaves and soil. Lead has been shown to be an inhibitor of cell division, water uptake, and photosynthesis, eventually causing death to the plant.
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Curiously, the testis contains factors such as cytokines, which are usually only produced upon infections and tissue damage. The cytokines interleukin-1α (IL-1α), IL-6 and Activin A are found in the testis, often at high levels. In other tissues, these cytokine would promote inflammation, but here they control testis function. They regulate the development of sperm by controlling their cell division and survival.
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Giant banded (Polytene) chromosomes resulting from the replication of the chromosomes and the synapsis of homologs without cell division is a process called endomitosis. These chromosomes consist of more than 1000 copies of the same chromatid that are aligned and produce alternating dark and light bands when stained. The dark bands are the chromomere. It is unknown when chromomeres first appear on the chromosome.
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She also spent time as a research fellow at the California Institute of Technology (Caltech), studying antibodies and cell division in sea-urchin eggs. From 1954 she was an associate professor at Texas Southern University (TSU) in Houston, becoming a full professor there in 1960 or 1961 until 1970. During the 1950s, she received several grants from the National Science Foundation for embryology studies.
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Schatten’s work on fertilization examines the differential inheritance of cellular components contributed by the sperm and egg, respectively, as well as the program of oocyte activation and cell division during meiosis and mitosis. His group has demonstrated the importance of the sperm centrosome-centriole complex during mammalian fertilization (including humans), with the unexpected exception of rodents in which the centrosome is of maternal origin (see Selected Publications).
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Although fungi are normally haploid, diploid cells can arise by two mechanisms. The first is a failure of the mitotic spindle during regular cell division, and does not involve karyogamy. The resulting cell can only be genetically homozygous since it is produced from one haploid cell. The second mechanism, involving karyogamy of somatic cells, can produce heterozygous diploids if the two nuclei differ in genetic information.
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The endoplasm, along with its granules, contains water, nucleic acids amino acids, carbohydrates, inorganic ions, lipids, enzymes, and other molecular compounds. It is the site of most cellular processes as it houses the organelles that make up the endomembrane system, as well as those that stand alone. The endoplasm is necessary for most metabolic activities, including cell division. The endoplasm, like the cytoplasm, is far from static.
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In addition to these 2 main processes, there are many other activities that take place in the endoplasm. Lysosomes degrade waste and toxins with the enzymes they contain. Smooth endoplasmic reticulum makes hormones and lipids, degrades toxins, and controls cellular levels of calcium. Though most control of cell division is present in the nucleus, the centrosomes present in the endoplasm assist with spindle formation.
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Hayflick demonstrated that a normal human fetal cell population will divide between 40 and 60 times in cell culture before entering a senescence phase. This finding refuted the contention by French Nobel laureate Alexis Carrel that normal cells are immortal. Each time a cell undergoes mitosis, the telomeres on the ends of each chromosome shorten slightly. Cell division will cease once telomeres shorten to a critical length.
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Hyde was a researcher and professor, but also an inventor and innovator. She developed instruments for monitoring physiological parameters in a marine animal that could be used in seawater. Her most well- known invention was an intracellular micropipette electrode. Dr. Hyde had observed that electrolytes in high concentrations affect processes of cell division, leading to her noting of the minute differences in electrical potential within cells.
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Mutations in this gene lead to impaired cell division during early development. Mitosis has been found to take longer when CENPF is mutated. Microtubules are protein structures that are part of the cytoskeleton and are necessary for cells to have diverse, complex shapes and migratory ability. They are made by the centrosome, which contains a pair of cylindrical centrioles at right-angles to each other.
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Following RGC proliferation, neurogenesis involves a final cell division of the parent RGC, which produces one of two possible outcomes. First, this may generate a subclass of neuronal progenitors called intermediate neuronal precursors (INP)s, which will divide one or more times to produce neurons. Alternatively, daughter neurons may be produced directly. Neurons do not immediately form neural circuits through the growth of axons and dendrites.
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One type connects to two basal bodies and one nucleus. The other type attaches to left and right plasma membrane at cell surfaces. The cell division of Trebouxia occurs by the cleavage of the chromatophore into two equal halves followed by the pyrenoid division. The pyrenoid can either divide by simple constriction or it can disappear during the division of the chromatophore as observed during zoosporogenesis.
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Levofloxacin is a broad- spectrum antibiotic that is active against both Gram-positive and Gram- negative bacteria. Like all quinolones, it functions by inhibiting the DNA gyrase and topoisomerase IV, two bacterial type II topoisomerases. Topoisomerase IV is necessary to separate DNA that has been replicated (doubled) prior to bacterial cell division. With the DNA not being separated, the process is stopped, and the bacterium cannot divide.
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A new epigenetic mark found in studies of aging cells is the loss of histones. Most of the evidence shows that loss of histones is linked to cell division. In aging and dividing yeast MNase-seq (Micrococcal Nuclease sequencing) showed a loss of nucleosomes of ~50%. Proper histone dosage is important in yeast as shown from the extended lifespans seen in strains that are overexpressing histones.
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Both the parents produce gametes through meiosis, a special type of cell division that reduces the chromosome number by half. During an early stage of meiosis, before the chromosomes are separated in the two daughter cells, the chromosomes undergo genetic recombination. This allows them to exchange some of their genetic information. Therefore, the gametes from a single organism are all genetically different from each other.
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Plasmids can be incompatible if they share the same replication control mechanism. Under these circumstances, both plasmids contribute to the total copy number and are regulated together. They are not recognized as distinct plasmids. As such, it becomes much more likely that one of the plasmids may be out-copied by the other and lost during cell division (the cell is "cured" of the plasmid).
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The device has been programmed to identify certain parameters and mount an appropriate response. The device searches for transcription factors proteins that control the expression of genes in the cell. A malfunction of these molecules can disrupt gene expression. In cancer cells, for example, the transcription factors regulating cell growth and division do not function properly, leading to increased cell division and the formation of a tumor.
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B.pseudomallei filaments revert to normal forms when the antibiotics are removed, and daughter cells maintain cell-division capacity and viability when re-exposed to antibiotics. Thus, filamentation may be a bacterial survival strategy. In Pseudomonas aeruginosa, antibiotic-induced filamentation appears to trigger a change from normal growth phase to stationary growth phase. Filamentous bacteria also release more endotoxin (lipopolysaccharide), one of the toxins responsible for septic shock.
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When these breaks occur, ATM stops the cell from making new DNA (cell cycle arrest) and recruits and activates other proteins to repair the damage. Thus, ATM allows the cell to repair its DNA before the completion of cell division. If DNA damage is too severe, ATM will mediate the process of programmed cell death (apoptosis) to eliminate the cell and prevent genomic instability.
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The ookinete is a motile cell, capable of invading other organs of the mosquito. It traverses the peritrophic membrane of the mosquito midgut and crosses the midgut epithelium. Once through the epithelium, the ookinete enters the basal lamina, and settles to an immotile oocyst. For several days, the oocyst undergoes 10 to 11 rounds of cell division to create a syncytial cell (sporoblast) containing thousands of nuclei.
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Robin Campbell Allshire (born 19 May 1960) One or more of the preceding sentences incorporates text from the royalsociety.org website where: is Professor of Chromosome Biology at University of Edinburgh and a Wellcome Trust Principal Research Fellow. His research group at the Wellcome Trust Centre for Cell Biology focuses on the epigenetic mechanisms governing the assembly of specialised domains of chromatin and their transmission through cell division.
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HPV E7 binds to retinoblastoma tumor suppressing proteins and limits its ability to control cell division. These two inhibitory proteins are partially responsible for HeLa cells' immortality by inhibiting apoptosis to occur. CDV (Canine Distemper Virus) is able to induce apoptosis despite the presence of these inhibitory proteins. This is an important oncolytic property of CDV: this virus is capable of killing canine lymphoma cells.
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Centrioles are generated in new daughter cells through duplication of pre-existing centrioles in the mother cells. Each daughter cell inherits two centrioles (one centrosome) surrounded by pericentriolar material as a result of cell division. However, the two centrioles are of different ages. This is because one centriole originates from the mother cell while the other is replicated from the mother centriole during the cell cycle.
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Tubulin in molecular biology can refer either to the tubulin protein superfamily of globular proteins, or one of the member proteins of that superfamily. α- and β-tubulins polymerize into microtubules, a major component of the eukaryotic cytoskeleton. Microtubules function in many essential cellular processes, including mitosis. Tubulin-binding drugs kill cancerous cells by inhibiting microtubule dynamics, which are required for DNA segregation and therefore cell division.
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For instance, enhanced activity of the enzyme has been implicated in the derangement of the function of certain systems, such as cell division. Also included are numerous diseases related to local inflammation such as atherosclerosis and psoriasis, or systemic inflammation such as sepsis and septic shock. A number of viruses target tyrosine kinase function during infection. The polyoma virus affects tyrosine kinase activity inside the nuclear matrix.
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At age 17, she wrote, edited and directed the short film Cell Division, which competed in film festivals around the country. She appears in the music video for Maroon 5's "Won't Go Home Without You". In 2013, Raymonde was cast in Chicago P.D., a spin-off of the NBC series Chicago Fire. She, along with co-star Scott Eastwood, left the show for creative reasons.
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Mitosis divides the chromosomes in a cell nucleus. During mitosis chromosome segregation occurs routinely as a step in cell division (see mitosis diagram). As indicated in the mitosis diagram, mitosis is preceded by a round of DNA replication, so that each chromosome forms two copies called chromatids. These chromatids separate to opposite poles, a process facilitated by a protein complex referred to as cohesin.
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Cell division control protein 42 (CDC42), a small Rho GTPase, regulates the formation of F-actin-containing structures through its interaction with the downstream effector proteins. The protein encoded by this gene is a member of the Borg (binder of Rho GTPases) family of CDC42 effector proteins. Borg family proteins contain a CRIB (Cdc42/Rac interactive- binding) domain. They bind to CDC42 and regulate its function negatively.
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By relation, it is thought that LIS1 is a factor in neuronal migration. LIS1 is also considered to be a factor in controlling dynein, a motor protein that affects intercellular movement such as protein sorting and the process of cell division. Another protein that contributes to a lissencephaly disorder is DCX, or Doublecortin. DCX is a microtubule associated protein that is responsible for double cortex malformations.
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When this happens, the sperm and egg cell fuse to form a zygote, the cell from which the sporophyte stage of the life cycle will develop. Unlike all other bryophytes, the first cell division of the zygote is longitudinal. Further divisions produce three basic regions of the sporophyte. At the bottom of the sporophyte (closest to the interior of the gametophyte), is a foot.
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This is advantageous as insertional mutagenesis is avoided. It is disadvantageous in that the progeny of the cell will lose the virus quickly through cell division unless the cell divides very slowly. AAVs differ from adenoviruses in that the viral genes have been removed and they have diminished packing capacity. Lentiviruses integrate into sections of transcriptionally active chromatin and are thus passed on to progeny cells.
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During mitosis, there are five stages of cell division: Prophase, Prometaphase, Metaphase, Anaphase, and Telophase. During prophase, two aster-covered centrosomes migrate to opposite sides of the nucleus in preparation of mitotic spindle formation. During prometaphase there is fragmentation of the nuclear envelope and formation of the mitotic spindles. During metaphase, the kinetochore microtubules extending from each centrosome connect to the centromeres of the chromosomes.
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Although tubulin-like proteins share some amino acid sequence similarity, their equivalence in protein-fold and the similarity in the GTP binding site is more striking. The same holds true for the actin-like proteins and their structure and ATP binding domain. Cytoskeletal proteins are usually correlated with cell shape, DNA segregation and cell division in prokaryotes and eukaryotes. Which proteins fulfill which task is very different.
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For example, DNA segregation in all eukaryotes happens through use of tubulin, but in prokaryotes either WACA proteins, actin-like or tubulin-like proteins can be used. Cell division is mediated in eukaryotes by actin, but in prokaryotes usually by tubulin-like (often FtsZ-ring) proteins and sometimes (Crenarchaeota) ESCRT-III, which in eukaryotes still has a role in the last step of division.
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CDC34 is a gene encoding a protein product that has ubiquitin conjugating activity. CDC34 was originally discovered by work in baker's yeast as a gene that has a role in the cell division cycle. Cdc34 in yeast targets numerous substrates (Sic1, Far1, Cln1, Cln2) for ubiquitin mediated degradation. Ubiquitin-conjugating enzyme E2 R1 is a protein that in humans is encoded by the CDC34 gene.
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Non-pulvinar mediated movement is also possible and happens through differential cell division and growth on either side of the petiole, resulting in a bending motion within the leaves to the desired position. Leaf movement is also controlled by bioactive substances known as leaf opening or leaf closing factors. Several leaf-opening and leaf- closing factors have been characterized biochemically. These factors differ among plants.
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In the body column of Hydra, there is continuous division of epithelial cells occurring while the size of the Hydra remains constant. The movement of individual neurons is coupled to the movement of epithelial cells. Experiments have provided evidence that once neurons are differentiated, epithelial cell division drives their insertion into the nerve net. As neurogenesis occurs, a density gradient of neuronal cells appears in the body.
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Blue light hits a plant's leaves and causes the downstream activation of proton pumps. In turn, this results in a decrease of the cell wall's pH. The decrease, in conjunction with membrane-bound proteins called expansins, increases the plasticity of the apoplastic membrane. This plasticity enables more cell area to be created during cell division, which expands the leaf as more standard- sized cells are added.
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Better crops with plant food, 83(1), 6-7. Within a plant cell these functions are imperative for function, in photophosphorylation for example the creation of stored energy in plants is a result of a chemical reaction including phosphorus. Phosphorus is a key molecular component of genetic reproduction. When phosphorus is present in inadequate levels, genetic processes such as cell division and plant growth are impaired.
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The g1 phase, or Gap 1 phase, is the first of four phases of the cell cycle that takes place in eukaryotic cell division. In this part of interphase, the cell synthesizes mRNA and proteins in preparation for subsequent steps leading to mitosis. G1 phase ends when the cell moves into the S phase of interphase. It takes 30-40 percentage time of a cell cycle.
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After the cell proceeds successfully through the M phase, it may then undergo cell division through cytokinesis. The control of each checkpoint is controlled by cyclin and cyclin-dependent kinases. The progression of interphase is the result of the increased amount of cyclin. As the amount of cyclin increases, more and more cyclin dependent kinases attach to cyclin signaling the cell further into interphase.
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There are several known causes for cavernous hemangiomas, but some cases are still unknown. Radiation treatment used for other medical conditions has been suggested to cause cavernous malformation in some patients. Hemangioma tumors are a result of rapid proliferation of endothelial cells and pericytic hyperplasia, or the enlargement of tissue as a result of abnormal cell division pericytes. The pathogenesis of hemangioma is still not understood.
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Drawing of Loxodes striatus during cell division (5), and its Müller vesicle (12) and nuclei in different stages of development (6-11). Loxodidae members possess the ability to orient themselves in oxygen gradients. They use gravity as a stimulus for this spatial orientation, a phenomenon called gravitaxis or geotaxis. Loxodid ciliates must therefore have developed mechanoreceptors informing them about what is up or down.
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During mitotic S phase, DNA replication produces two nearly identical sister chromatids. DNA double-strand breaks that arise after replication has progressed or during the G2 phase can be repaired before cell division occurs (M-phase of the cell cycle). Thus, during the G2 phase, double-strand breaks in one sister chromatid may be repaired by homologous recombinational repair using the other intact sister chromatid as template.
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C. uncinata goes through asexual reproduction for cell division and duplication called amitosis. As C. uncinata has two nuclei, it goes through two different styles of division of the nuclei. The germ-line nucleus goes through mitosis during asexual division while the somatic nucleus undergoes amitosis. Amitosis is a stochastic process where unlike in mitosis, there is no spindle formation to segregate chromosomes during nuclear division.
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Plant physiologists have identified four different stages the plant goes through after the apex is removed (Stages I-IV). The four stages are referred to as # lateral bud formation, # "imposition of inhibition" (apical dominance), # initiation of lateral bud outgrowth following decapitation, and # elongation and development of the lateral bud into a branch. These stages can also be defined by the hormones that are regulating the process which are as follows: Stage I, cytokinin promoted, causing the lateral bud to form since cytokinin plays a role in cell division; Stage II, auxin is promoted, resulting in apical dominance ("imposition of inhibition"); Stage III, cytokinin released resulting in outward growth of the lateral bud; and Stage IV, auxin is decreased and gibberellic acid is promoted which results in cell division, enabling the bud or branch to continue outward growth. More simply stated, lateral bud formation is inhibited by the shoot apical meristem (SAM).
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Growth from any such meristem at the tip of a root or shoot is termed primary growth and results in the lengthening of that root or shoot. Secondary growth results in widening of a root or shoot from divisions of cells in a cambium. In addition to growth by cell division, a plant may grow through cell elongation. This occurs when individual cells or groups of cells grow longer.
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All three types of keratinocytes are present in the basal layer of the limbus, with holoclones in the least abundance (10%–15%). The basal layer of the cornea is populated by meroclones and paraclones at the periphery, and only paraclones in the central cornea, reflecting the above process of cell division and differentiation. Holoclones are identified by high expression of the marker p63 and are also known as p63 bright cells.
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The cytokinin zeatin is named after the genus of corn, Zea. Cytokinins (CK) are a class of plant growth substances (phytohormones) that promote cell division, or cytokinesis, in plant roots and shoots. They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth, and leaf senescence. Folke Skoog discovered their effects using coconut milk in the 1940s at the University of Wisconsin–Madison.
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Planktothrix grow by cell division in a single plane to form unbranched structures of average length around 4 μm, but unlike other Oscillatoriales, these trichomes are phototactic. Typically, Planktothrix filaments do not have specialized cells such as akinetes or heterocysts, and do not produce mucilaginous envelopes, except for some rare species but only under stress conditions. Several species possess constant ratio of their two main photosynthetic pigments, i.e., phycocyanins and phycoerythrins.
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The haploid gametophyte has n unpaired chromosomes, i.e. half the number of the sporophyte. The gametophyte of ferns is a free-living organism, whereas the gametophyte of the gymnosperms and angiosperms is dependent on the sporophyte. The life cycle of a typical fern proceeds as follows: # A diploid sporophyte phase produces haploid spores by meiosis (a process of cell division which reduces the number of chromosomes by a half).
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Inouye was born in Port Arthur in Manchuria in 1934 and after the World War II, he went back to Japan. He studied at Osaka University, Japan and got his Ph.D. in 1963. After 5-years postdoctoral experience, he moved to Princeton University as a research associate working on the mechanism of cell division. 1970, he joined the faculty at State University of New York at Stony Brook.
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In fact, in association with SMC3, it is recruited to mitotic spindle poles through interaction with RAE1. The dysregulation of SMC1A (both down- and up-regulation) causes aberrant multi-polar spindles, suggesting that cohesin would function to hold microtubules at the spindle pole. Proper cohesion of sister chromatids is a prerequisite for the correct segregation of chromosomes during cell division. The cohesin multiprotein complex is required for sister chromatid cohesion.
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Not only does p16 play an important role in aging, but also in auto-immune diseases like rheumatoid arthritis that progressively lead to mobility impairment in advanced disease. In the nervous system, senescence has been described in astrocytes and microglia, but is less understood in neurons. Because senescence arrests cell division, studies of senescence in the brain were focused mainly on glial cells and less studies were focused on nondividing neurons.
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Many of the physical malformations associated with Roberts syndrome are very similar to the malformations that occur in children whose mothers took thalidomide during pregnancy. The physical similarities suggest that there is a similar underlying biology between ESCO2 and thalidomide. As a result, it is speculated that thalidomide affects chromosomes and cell division in a similar manner to ESCO2. For this reason, Roberts syndrome is sometimes called Pseudothalidomide Syndrome.
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This work required the development of a new technique to separate the inner and outer membranes of Gram-negative bacteria, which became known as the Osborn method. She also researched the mechanisms of bacterial cell division. Later in her career, she pursued an interest in space biology. Osborn worked for NASA and the National Research Council from the mid-1990s through 2008 on lunar and space exploration projects.
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An image of a newt lung cell stained with fluorescent dyes during metaphase. The mitotic spindle can be seen, stained green, attached to the two sets of chromosomes, stained light blue. All chromosomes but one are already at the metaphase plate. During its lifetime, a nucleus may be broken down or destroyed, either in the process of cell division or as a consequence of apoptosis (the process of programmed cell death).
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These autospores (spores having the same distinctive shape as the parent cell) are liberated by the rupture of the parent cell wall (D). On release each autospore grows to become a new individual. the presence of sulphur in the culture medium is considered essential for cell division. it takes place even in the dark with sulphur alone as the source material but under light conditions nitrogen also required in addition.
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Springer New York. The first two species described for the genus, R. fermentans and R. antarcticus, are facultative photoheterotrophs that can grow anaerobically when exposed to light and aerobically under dark conditions at atmospheric levels of oxygen. R. ferrireducens is a nonphototrophic facultative anaerobe capable of reducing Fe(III) at temperatures as low as 4 °C. R. saidenbachensis grows strictly aerobic and has a very low rate of cell division.
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Therefore, the quantification of provirus reflects the number of HTLV-1-infected cells. So, an increase in numbers of HTLV-1-infected cells using cell division, by actions of accessory viral genes, especially Tax, may provide an enhancement of infectivity. Tax expression induces proliferation, inhibits the apoptosis of HTLV-1-infected cells and, conversely, evokes the host immune response, including cytotoxic T cells, to kill virus-infected cells. Figure 1.
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In multicellular organisms, every cell in the organism's body derives ultimately from a single cell in a fertilized egg. The cell is also considered to be the basic unit in many pathological processes. In addition, the phenomenon of energy flow occurs in cells in processes that are part of the function known as metabolism. Finally, cells contain hereditary information (DNA), which is passed from cell to cell during cell division.
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When the enzyme is inhibited by methotrexate, the cellular levels of folate coenzymes diminish. These are required for thymidylate and purine production, which are both essential for DNA synthesis and cell division. Pemetrexed is another anti-metabolite that affects purine and pyrimidine production, and therefore also inhibits DNA synthesis. It primarily inhibits the enzyme thymidylate synthase, but also has effects on DHFR, aminoimidazole carboxamide ribonucleotide formyltransferase and glycinamide ribonucleotide formyltransferase.
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Other autosomal dominant diseases can be inherited from one parent, such as Huntington disease and DiGeorge syndrome. Yet other genetic disorders are caused by an error or mutation occurring during the cell division process (e.g. aneuploidy) and are not hereditary. Screening tests are often used prior to diagnostic testing, designed to separate people according to a fixed characteristic or property, with the intention of detecting early evidence of disease.
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This results in an obconical meristematic cell. Division by this type of cell is parallel to each other and perpendicular to the rest of the cells, forming rows. This eventually results in the formation of a notch at the anterior edge of the prothallus, giving it a roughly heart-shaped appearance (cordate). The cordate prothallus are usually smaller with thinner midribs than that of other members of Polypodiaceae.
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In some cases, such as Pelophylax esculentus, there is also endomeiosis prior to cell division, which means that the maternal chromosomes are duplicated and each egg contains identical pairs of chromosomes. Hybridogenesis can be described as a parthenogenetic-like mode of reproduction, since there is no continuing heredity in the paternal line . It has been documented in the European water frog complex of the genus Pelophylax, which includes three hybridogenic forms.
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After the process of cavitation occurs the blastocoel forms. Following the formation of the blastocoel, the inner mass of cells positions itself in one portion of the inner cavity, while the rest of the cavity is filled with fluid. Cavitation is a crucial process in the development of mammalian embryos. After fertilization, rapid cell division occurs which results in the formation of the morula, or a solid ball of cells.
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The mutations producing the differences detected in this study would have occurred during embryonic cell-division (after the point of fertilization). If they occur early in fetal development, they will be present in a very large proportion of body cells. Another cause of difference between monozygotic twins is epigenetic modification, caused by differing environmental influences throughout their lives. Epigenetics refers to the level of activity of any particular gene.
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Since its initial discovery, Wnt signaling has had an association with cancer. When Wnt1 was discovered, it was first identified as a proto-oncogene in a mouse model for breast cancer. The fact that Wnt1 is a homolog of Wg shows that it is involved in embryonic development, which often calls for rapid cell division and migration. Misregulation of these processes can lead to tumor development via excess cell proliferation.
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Another labelling protein, digoxigenin, is attached to the reference DNA sample. The labelled DNA samples are co- hybridized to probes during cell division, which is the most informative time for observing copy number variation. CGH uses creates a map that shows the relative abundance of DNA and chromosome number. By comparing the fluorescence in a sample compared to a reference, CGH can point to gains or losses of chromosomal regions.
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DNA and RNA), which are required for cell division. Thus, it has a microbiostatic effect rather than a microbiocidal one (it prevents pathogen growth rather than killing them), and has the strongest effect in the beginning stages of an infection, when the pathogen is rapidly dividing. Since it is microbiostatic, sulfadimethoxine still requires the animal to still be able to mount an immune response to kill the pathogen.
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This hedgehog has no pigmentation due to a mutation. Mutations are permanent, transmissible changes to the genetic material (DNA or RNA) of a cell or virus. Mutations result from errors in DNA replication during cell division and by exposure to radiation, chemicals, and other environmental stressors, or viruses and transposable elements. Most mutations that occur are single nucleotide polymorphisms which modify single bases of the DNA sequence, resulting in point mutations.
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As a result any changes observed after a stimulus is applied can be statistically correlated and it could be decided if these changes are reactions to the stimulus or just merely coincidental. In this moment BY-2 cells are relatively well understood and often used in research. This model plant system is especially useful for studies of cell division, cytoskeletons, plant hormone signaling, intracellular trafficking, and organelle differentiation.
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The number of multidrug-resistant bacterial strains is currently increasing; thus, the determination of drug targets for the development of novel antimicrobial drugs is urgently needed. The potential role of FtsZ in the blockage of cell division, together with its high degree of conservation across bacterial species, makes FtsZ a highly attractive target for developing novel antibiotics. Researchers have been working on synthetic molecules and natural products as inhibitors of FtsZ.
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In many cases, gatekeeper genes encode a system of checks and balances that monitor cell division and death. When tissue damage occurs, for example, products of gatekeeper genes ensure that balance of cell growth over cellular death remains in check. In the presence of competent gatekeeper genes, mutations of other genes do not lead to on-going growth imbalances. Mutations altering these genes lead to irregular growth regulation and differentiation.
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In both cases, the inverted duplicated marker forms only after cell division and replication by rejoining the broken, replicated ends of the fragment. It is also suggested that U-type exchange during meiosis I may lead to partial tetrasomy. On the other hand, Class II marker chromosomes result from the second most common type of rearrangement: interstitial deletions. A chromosome is rearranged to give a ring chromosome, and a linear chromosome.
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Flemming furthered this description in 1874 and 1875 as he explained the steps in more detail. He also argued with Schneider's findings that the nucleus separated into rod-like structures by suggesting that the nucleus actually separated into threads that in turn separated. Flemming concluded that cells replicate through cell division, to be more specific mitosis. Matthew Meselson and Franklin Stahl are credited with the discovery of DNA replication.
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The pathogenesis of polymicrogyria is still being researched for understanding though it is historically heterogeneous-4. It results from both genetic and destructive events. While polymicrogyria is associated with genetic mutations, none of these are the sole cause of this abnormality. The cortical development of mammals requires specific cell functions that all involve microtubules, whether it is because of mitosis, specifically cell division, cell migration or neurite growth.
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A series of several mutations to certain classes of genes is usually required before a normal cell will transform into a cancer cell. On average, for example, 15 "driver mutations" and 60 "passenger" mutations are found in colon cancers. Mutations in genes that regulate cell division, apoptosis (cell death), and DNA repair may result in uncontrolled cell proliferation and cancer. Cancer is fundamentally a disease of regulation of tissue growth.
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This was the time that the mechanisms of cell division began to be understood. Eduard Strasburger, Walther Flemming, Heinrich von Waldeyer and the Belgian Edouard Van Beneden laid the basis for the cytology and cytogenetics of the 20th century. Strasburger, the outstanding botanical physiologist of that century, coined the terms nucleoplasm and cytoplasm. He said "new cell nuclei can only arise from the division of other cell nuclei".
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Cadmium has been shown to be carcinogenic due to interactions with DNA topoisomerase IIα. This enzyme helps facilitate cell division and DNA repair, specifically with double strand breaks. Cadmium cations react with the topoisomerase in the following manner: 8 Cd2+ \+ topoisomerase IIα – 8H --> topoisomerase IIα – 8 Cd2+ Here, the cadmium ions react with sulfur-containing thiol groups in cysteine residues, effectively ruining the structure and function of the topoisomerase.
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Encystment protects the protist from environmental changes, the cyst can be a site for nuclear reorganization and cell division, and it can act as a host cell in order to transfer parasitic species. Excystment is when a return to favorable conditions may cause a cyst to return to its original state. In parasitic protists, excystment may occur when the cyst is ingested by a new host. Protists reproduce asexually or sexually.
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Apoptosis—phagocytes clear fragments of dead cells from the body In an animal, cells are constantly dying. A balance between cell division and cell death keeps the number of cells relatively constant in adults. There are two different ways a cell can die: by necrosis or by apoptosis. In contrast to necrosis, which often results from disease or trauma, apoptosis—or programmed cell death—is a normal healthy function of cells.
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Other treatments include, epilation of the infected follicles, topical ointments and steroidal treatments. Topical ointments immobilize the fungus and reduce shedding but they do not penetrate the hair follicle and hence must be used in conjunction with other treatment methods. Steroidal treatments aid in inflammation and pain reduction. Griseofulvin inhibits fungal cell mitosis via disruption of the mitotic spindle structure and preventing cell division at the metaphase stage.
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The unregulated cell division that marks cancer development requires increased protein synthesis for cancer cell function and survival. This increased protein synthesis is typically seen in proteins that modulate cell metabolism and growth processes. Cancer cells are sometimes susceptible to drugs that inhibit chaperones and disrupt proteostasis, such as Hsp90 inhibitors or proteasome inhibitors. Furthermore, cancer cells tend to produce misfolded proteins, which are removed mainly by proteolysis.
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If two cells of the same type meet in this phase, they cross- fertilise to a diploid zygote through the fusion of protoplasms and nuclei. The conditions which trigger this are not known. The diploid zygote becomes a multinucleated plasmodium through multiple nuclear divisions without further cell division. If the resulting cells were peritrichous, they change their shape before the fusion from the peritrichous form to the myxamoeba.
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Plks have been found to cooperate with Cdks in the orchestration of cell division. Entry into M phase is controlled through the activation of cyclin-dependent kinase 1 (CDK1)–cyclin B, and Cdc25 is a phosphatase that dephosphorylates Cdk1 to promote mitotic entry. Plk1 binds to phosphorylated Cdc25 through its PBD.Kumagai, A. & Dunphy, W. G. Purification and molecular cloning of Plx1, a Cdc25-regulatory kinase from Xenopus egg extracts.
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Protein cyclin A governs this process by keeping the process going until the errors are eliminated. In normal cells, persistent cyclin A expression prevents the stabilization of microtubules bound to kinetochores even in cells with aligned chromosomes. As levels of cyclin A decline, microtubule attachments become stable, allowing the chromosomes to be divided correctly as cell division proceeds. In contrast, in cyclin A-deficient cells, microtubule attachments are prematurely stabilized.
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The number of nuclear divisions prior to cell division dictates the number of spores which will be produced, this can vary even between individuals in the same species. Next, autospores are produced inside the mother cell’s mucilage forming an autosporangium. When the spores are formed, the autosporangium decays by rupturing or dissolving, depending on the species. As Dictyochloropsis cells prepare to divide, several intracellular changes happen to the chloroplast.
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Swarmer cells become stalked cells after a short period of motility. Chromosome replication and cell division only occur in stalked cells. Rather than containing an evenly dispersed mixture of proteins, the single celled Caulobacter resembles a highly organized factory, with specific "machinery" regulating each step in the cell cycle to ensure that changes occur at developmentally appropriate times. DNA is copied once per cycle by a particular group of molecules.
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In some cells, the nucleus divides before the second division of chromatophore halves whereas in other cells it divides after the second division of the chromatophore by migrating to centre of cell between chromatophore halves. The detail of cell division is understudied and more research needs to be conducted. Trebouxia has a complex life cycle. The details of the life cycle are not properly understood and more research is required.
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DNA is not completely unwound during replication. It is possible, then, that the modified histones may be carried into each new copy of the DNA. Once there, these histones may act as templates, initiating the surrounding new histones to be shaped in the new manner. By altering the shape of the histones around them, these modified histones would ensure that a lineage-specific transcription program is maintained after cell division.
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The Ti plasmid is maintained at low copy numbers within a bacterial cell. This is partly achieved by influencing the expression of the replication initiator RepC. When bound to ADP, RepA is activated to work with RepB, acting as a negative regulator of the repABC cassette. The levels of RepC is therefore kept low within a cell, preventing too many rounds of replication from occurring during each cell division cycle.
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One group is responsible for the production of plant growth hormones. As these hormones are produced, there will be an increase in the rate of cell division and therefore the formation of crown gall tumors. The second group of proteins are responsible for driving the synthesis of opines in the host plant cells. The specific opines produced depends on the type of the Ti plasmid but not on the plant host.
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This protein can have a new function that promotes the development of cancer. Examples of this include the ETV6-RUNX1 fusion gene that combines two factors that promote blood cell development and the BCR-ABL1 fusion gene of the Philadelphia chromosome. BCR-ABL1 encodes an always- activated tyrosine kinase that causes frequent cell division. These mutations produce a cell that divides more often, even in the absence of growth factors.
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The tetrasomy is typically caused by the incorrect distribution of chromosomes during meiosis or mitosis, called nondisjunction. When cell division occurs normally, each daughter cell receives one short arm and one long arm of each chromosome. However, errors during this process may cause one daughter cell to receive two short arms of chromosome 9, while the other cell receives two long arms. The identical arms are subsequently connected via a centromere.
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The function of the vacuole is still unclear, however, it has been suggested that, like for many eukaryotic cells, it is for storage purposes. Other functions, such as cell division during reproduction and the deposition of apoptotic bodies, have been proposed, although more tests need to be done to validate these roles. Four common forms of Blastocystis hominis. Clockwise from top left: vacuolar, granular, amoeboid, and cyst forms.
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Unlike true stem cells, callus is heterogeneous. Due to this reason, continuous and stable cell division of callus is difficult. Hence a plant stem cell originated from cambium is an immortal cell while that from callus is a temporarily dediffertiated cell obtained from stimulating the somatic cell. Furthermore, the ability to differentiate and proliferate is different that differences between plant stem cell and callus are prevalent in culture and research.
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Their product (PBP-3), as mentioned above, is a membrane transpeptidase required for peptidoglycan synthesis at the septum. Inactivation of the ftsl gene product requires the SOS-promoting recA and lexA genes as well as dpiA and transiently inhibits bacterial cell division. The DpiA is the effector for the DpiB two-component system. Interaction of DpiA with replication origins competes with the binding of the replication proteins DnaA and DnaB.
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Actin microfilaments have been widely studied using cytochalasins. Due to their chemical nature, cytochalasins can help researchers understand the importance of actin in various biological processes. The use of cytochalasins has allowed researchers to better understand actin polymerization, cell motility, ruffling, cell division, contraction, and cell stiffness. The use of cytochalasins has been so important to understanding cytoskeletal movement and many other biological processes, researchers have created two synthetic cytochalasins.
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Microbes trigger development of isolated lymphoid follicles in the small intestine of humans and mice, which are sites of mucosal immune response. Isolated lymphoid follicles (ILFs) collect antigens through M cells, develop germinal centers, and contain many B cells. Gram-negative commensal bacteria trigger the development of inducible lymphoid follicles by releasing peptidogylcans containing diaminopimelic acid during cell division. The peptidoglycans bind to the NOD1 receptor on intestinal epithelial cells.
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Human embryonic development refers to the development and formation of the human embryo. It is characterised by the process of cell division and cellular differentiation of the embryo that occurs during the early stages of development. In biological terms, human development entails growth from a one-celled zygote to an adult human being. Fertilisation occurs when the sperm cell successfully enters and fuses with an egg cell (ovum).
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Joan V. Ruderman (born 1947/48) is an American molecular and cell biologist. She is a Professor Emeritus at Harvard University and Visiting Senior Biologist at Princeton University. She has researched cell division and embryo development, and more recently the effects of, and the public understanding of, environmental estrogens and other endocrine disruptors. She was elected as a member of the United States National Academy of Sciences in 1998.
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Accessed 2016-04-06. It needs an ATPase to identify, unfold, and transfer targeted big proteins into its proteolytic channel. In fact, ClpP on its own can only degrade peptides that are up to six amino acids long. ADEP binding induces ClpP proteolytic activation that leads to the proteins degradation in the cell, especially nascent proteins and the Ftsz protein which is an important protein in cell division.
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The book proceeds along two "tracks": one series of photographs and accompanying text depict the development of the fetus from conception through to birth; the other shows a woman and her partner as her pregnancy progresses. Early images show sperm proceeding toward an ovum; cell division, implantation, and the development of the embryo are then illustrated. The text accompanying the photographs of the woman supplies some antenatal care advice.
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The Klebsormidiaceae are a family containing three genera of charophyte green alga forming multicellular, non-branching filaments. A fourth genus Chlorokybus is sometimes included as well, but this problematic and poorly known genus is sometimes placed in a separate class Chlorokybophyceae. Klebsormidiacea may be sister to Phragmoplastophyta, together forming the Streptophyte clade. The genera Koliella and Raphidonema were formerly classified as close relatives of Klebsormidium, based on similarities in cell division.
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For example, stretches of DNA in human sperm which lack methylation are more prone to mutation. In general, the mutation rate in unicellular eukaryotes (and bacteria) is roughly 0.003 mutations per genome per cell generation. However, some species, especially the ciliate of the genus Paramecium have an unusually low mutation rate. For instance, Paramecium tetraurelia has a base-substitution mutation rate of ~2 × 10−11 per site per cell division.
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Sir Richard Timothy Hunt, (born 19 February 1943) is a British biochemist and molecular physiologist. He was awarded the 2001 Nobel Prize in Physiology or Medicine with Paul Nurse and Leland H. Hartwell for their discoveries of protein molecules that control the division of cells. While studying fertilized sea urchin eggs in the early 1980s, Hunt discovered cyclin, a protein that cyclically aggregates and is depleted during cell division cycles.
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The dysgenic testis can have adequate functional tissue to produce satisfactory levels of testosterone to cause masculinisation. Mixed gonadal dysgenesis is poorly understood at the molecular level. The loss of the Y chromosome can occur from deletions, translocations, or migration failure of paired chromosomes during cell division. The chromosomal loss results in partial expression of the SRY gene, giving rise to abnormal development of the reproductive tract and altered hormones levels.
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Cytokinesis illustration Cilliate undergoing cytokinesis, with the cleavage furrow being clearly visible. Cytokinesis () is the part of the cell division process during which the cytoplasm of a single eukaryotic cell divides into two daughter cells. Cytoplasmic division begins during or after the late stages of nuclear division in mitosis and meiosis. During cytokinesis the spindle apparatus partitions and transports duplicated chromatids into the cytoplasm of the separating daughter cells.
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The astral microtubules originating from centrosomes reach the cell membrane where they are pulled towards specific cortical clues. In vitro, the distribution of cortical clues is set up by the adhesive pattern. In vivo polarity cues are determined by localization of Tricellular junctions localized at cell vertices. The spatial distribution of cortical clues leads to the force field that determine final spindle apparatus orientation and the subsequent orientation of cell division.
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While in bacterial cell division, after duplication of DNA, two circular chromosomes are attached to a special region of the cell membrane, eukaryotic mitosis is usually characterized by the presence of many linear chromosomes, whose kinetochores attaches to the microtubules of the spindle. In relation to the forms of mitosis, closed intranuclear pleuromitosis seems to be the most primitive type, as it is more similar to bacterial division.
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The FPC protein is also found on the centrosomes and mitotic spindle and may regulate centrosome duplication and mitotic spindle assembly during cell division. There have been a large number of various single gene mutations found throughout PKHD1 and are unique to individual families. Most of the patients are compound heterozygotes for PKHD1 mutations. Patients with two nonsense mutations appear to have an earlier onset of the disease.
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In vertebrate cells, replication sites concentrate into positions called replication foci. Replication sites can be detected by immunostaining daughter strands and replication enzymes and monitoring GFP-tagged replication factors. By these methods it is found that replication foci of varying size and positions appear in S phase of cell division and their number per nucleus is far smaller than the number of genomic replication forks. P. Heun et al.
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Finally, adding p53-MDM2 complexes displaces p53 and activates the p53 pathway, leading to cell cycle arrest and apoptosis. Many different methods can be used either to stimulate or to inhibit apoptosis in various places along the death signaling pathway. Apoptosis is a multi-step, multi-pathway cell-death programme that is inherent in every cell of the body. In cancer, the apoptosis cell-division ratio is altered.
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Growth from any such meristem at the tip of a root or shoot is termed primary growth and results in the lengthening of that root or shoot. Secondary growth results in widening of a root or shoot from divisions of cells in a cambium. In addition to growth by cell division, a plant may grow through cell elongation. This occurs when individual cells or groups of cells grow longer.
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However, as the DNA replication or transcription fork moves forward and positive supercoiling increases, the DNA strands wrap tighter and tighter around each other, making it more difficult for the polymerase to move forward. It is important for the local topology of DNA ahead of and behind the polymerase to be relieved so that replication and cell division can proceed. This is what DNA topoisomerases are used for.
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The way these cells regenerate and replace themselves is quite unique. While going through cell division, one of the two daughter cells actually becomes a new stem cell. This occurs so then that daughter cell can end up restoring the population of the stem cells that were lost. The other daughter cell separates itself into a functional cell in order to replace the lost, or injured cells during this process.
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This information is read using the genetic code, which specifies the sequence of the amino acids within proteins. The code is read by copying stretches of DNA into the related nucleic acid RNA in a process called transcription. Within cells, DNA is organized into long structures called chromosomes. During cell division these chromosomes are duplicated in the process of DNA replication, providing each cell its own complete set of chromosomes.
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Growth from any such meristem at the tip of a root or shoot is termed primary growth and results in the lengthening of that root or shoot. Secondary growth results in widening of a root or shoot from divisions of cells in a cambium. In addition to growth by cell division, a plant may grow through cell elongation. This occurs when individual cells or groups of cells grow longer.
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Uramustine (INN) or uracil mustard is a chemotherapy drug which belongs to the class of alkylating agents. It is used in lymphatic malignancies such as non- Hodgkin's lymphoma. It works by damaging DNA, primarily in cancer cells that preferentially take up the uracil due to their need to make nucleic acids during their rapid cycles of cell division. The DNA damage leads to apoptosis of the affected cells.
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Cyclin B was found to interact with this protein, which targets cell division cycle 2 (CDC2) kinase to microtubules. The phosphorylation of this protein affects microtubule properties and cell cycle progression. Multiple alternatively spliced transcript variants encoding distinct isoforms have been observed, the full- length nature of three of which are supported. uMAP4, the ubiquitous isoform of MAP4, functions in the architecture and positioning of the mitotic spindle in human cells.
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DicF RNA is a non-coding RNA that is an antisense inhibitor of cell division gene ftsZ. DicF is bound by the Hfq protein which enhances its interaction with its targets. Pathogenic E. coli strains possess multiple copies of sRNA DicF in their genomes, while non-pathogenic strains do not. DicF and Hfq are both necessary to reduce FtsZ protein levels, leading to cell filamentation under anaerobic conditions.
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These proteins may play a role in the control of cell division and growth regulation. GPC3 interacts with both Wnt and frizzled (FZD) to form a complex and triggers downstream signaling. The core protein of GPC3 may serve as a co-receptor or a receiver for Wnt. A cysteine-rich domain at the N-lobe of GPC3 has been identified as a hydrophobic groove that interacts with Wnt3a.
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This gene is a member of the septin gene family of nucleotide binding proteins, originally described in yeast as cell division cycle regulatory proteins. Septins are highly conserved in yeast, Drosophila, and mouse and appear to regulate cytoskeletal organization. Disruption of septin function disturbs cytokinesis and results in large multinucleate or polyploid cells. This gene is mapped to 22q11, the region frequently deleted in DiGeorge and velocardiofacial syndromes.
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The majority of research in nutriepigenomics has focused on nutritional imbalances during gestation and lactation periods. However, foods that are consumed during adulthood can also impact gene expression and disease pathogenesis. Cancer is the disease most commonly associated with adult nutrition and epigenetic modifications. DNA hypomethelation promotes cancer progression by allowing increased gene transcription, while hypermethylation can silence tumor suppressor genes and further promote uncontrolled cell division and tumor formation.
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The membrane bilayer is not always flat. Local curvature of the membrane can be caused by the asymmetry and non-bilayer organization of lipids as discussed above. More dramatic and functional curvature is achieved through BAR domains, which bind to phosphatidylinositol on the membrane surface, assisting in vesicle formation, organelle formation and cell division. Curvature development is in constant flux and contributes to the dynamic nature of biological membranes.
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Although preferentially cytosolic, SIRT2 transiently shuttles to the nucleus during the G2/M transition of the cell cycle, where it has a strong preference for histone H4 lysine 16 (H4K16ac), thereby regulating chromosomal condensation during mitosis. During the cell cycle, SIRT2 associates with several mitotic structures including the centrosome, mitotic spindle, and midbody, presumably to ensure normal cell division. Finally, cells with SIRT2 overexpression exhibit marked prolongation of the cell cycle.
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A knockout mouse (left) that is a model for obesity, compared with a normal mouse. There are several thousand different strains of knockout mice. Many mouse models are named after the gene that has been inactivated. For example, the p53 knockout mouse is named after the p53 gene which codes for a protein that normally suppresses the growth of tumours by arresting cell division and/or inducing apoptosis.
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Little has been documented about the morphology of Sulcia muelleri. Sulcia muelleri is a rod-shaped bacterium measuring 5–7 μm in length, .7 μm in diameter and 2–5 μm in width. Because S. muelleri lacks most of the genes responsible for cell division and membrane synthesis, it is sometimes observed to extend to unusual lengths of up to 100 μm during part of its life cycle.
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The germ cells split into two populations and move to the paired gonadal ridges. Migration starts with 3-4 cells that undergo three rounds of cell division so that about 30 PGCs arrive at the gonads. On the migratory path of the PGCs, the orientation of underlying cells and their secreted molecules such as fibronectin play an important role. Mammals have a migratory path comparable to that in Xenopus.
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Asci of Morchella elata, Phase contrast image There are 8 ascospores in each ascus of Sordaria fimicola. An ascus (plural asci; from Greek ' 'skin bag') is the sexual spore-bearing cell produced in ascomycete fungi. Each ascus usually contains eight ascospores (or octad), produced by meiosis followed, in most species, by a mitotic cell division. However, asci in some genera or species can occur in numbers of one (e.g.
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The interaction between stromal cells and tumor cells is known to play a major role in cancer growth and progression. In addition, by regulating local cytokine networks (e.g. M-CSF, LIF), bone marrow stromal cells have been described to be involved in human haematopoiesis and inflammatory processes. Stromal cells (in the dermis layer) adjacent to the epidermis (the top layer of the skin) release growth factors that promote cell division.
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Microtubules are long polymers made of smaller units (monomers) of the protein tubulin. Microtubules are created during normal cell functions by assembling (polymerizing) tubulin components, and are disassembled when they are no longer needed. One of the important functions of microtubules is to move and separate chromosomes and other components of the cell for cell division (mitosis). Mitotic inhibitors interfere with the assembly and disassembly of tubulin into microtubule polymers.
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Cell division is stimulated in the hypodermis and cortex, which leads to the formation of a "prenodule". The bacterium then migrates into the cortex of the root while the nodule continues to develop in the same way as a lateral root. Nodule lobe primordia develop in the pericycle, endodermis or cortex during the development of the prenodule and finally the bacterium enters the cells of these to infect the new nodule.
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Hydra undergoes morphallaxis (tissue regeneration) when injured or severed. Typically, Hydras will reproduce by just budding off a whole new individual, the bud will occur around two-thirds of the way down the body axis. When a Hydra is cut in half, each half will regenerate and form into a small Hydra; the "head" will regenerate a "foot" and the "foot" will regenerate a "head". This regeneration occurs without cell division.
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Working in Xenopus (frog) egg extracts, Kirschner and Andrew Murray showed that cyclin synthesis drives the cell cycle Pulverer, Bernd "Milestones in cell division (12): Surfing the cyclin wave" Nature Publishing Group (retrieved 16 May 2012) and, later, that ubiquitin regulates levels of cyclin by marking the cell-cycle molecule for destruction.Brooksbank, Cath "Milestones in cell division (20): Disappearing Act" Nature Publishing Group (retrieved 16 May 2012) His lab discovered and purified many of the components involved in cell cycle progression, including anaphase promoting complex (APC), the complex that ubiquitinates cyclin B. A second notedLewin, B "Great experiments: Dynamic instability of microtubules - Marc Kirschner and Tim Mitchison", CELLS! The web site accompanying the Cells textbook (Jones and Bartlett Publishers (2007) finding was his discovery, with Tim Mitchison, of the dynamic instability of microtubules, In mitosis, for example, microtubules form the spindle that separates the chromosomes. The first step in spindle formation is the nucleation of microtubules by microtubule-organizing centers, which then grow in all directions.
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Raised levels of PLK1 increase the probability of improper segregation of chromosomes which is a critical stage in the development of many cancers. Raised levels of PLK1 have been associated with a poorer prognosis and overall survival in some cancers In addition to its role in cell division, there is evidence that PLK1 also interacts with components of other pathways involved in cancer development including the K-Ras oncogene and the retinoblastoma and p53 tumour suppressors These observations have led to PLK1 being recognised as an important target in the treatment of cancer. Volasertib can be taken either orally or via intravenous infusion, once circulating in the blood stream it is distributed throughout the body, crosses the cell membrane and enters the nucleus of cells where it binds to its target; PLK1. Volasertib inhibits PLK1 preventing its roles in the cell-cycle and cell division which leads to cell arrest and programmed cell death.
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NuSAP is a substrate of cyclin F that is involved in cell division. It is a microtubule-associated protein that is required for the spindle assembly process. Its function is to interact with microtubules and chromatin to create stabilization and cross- linking. A lack of NuSAP has been linked with an increase in mutations due to impaired chromosome alignment during metaphase, while an excess of NuSAP leads to mitotic arrest and microtubule bundling.
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In principle, this approach could be selective for cancer cells in regions of the body, such at the brain, where the majority of normal cells are non-proliferating. During cell division, a structure called a spindle self-assembles from proteins. The spindle attaches to the 23 chromosomes and pulls the DNA into two new cells. The proteins in the spindle have a positive charge on one end and negative charge on the other end.
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Cell growth, division & proliferation Tissue growth is the process by which a tissue increases its size. In animals, tissue growth occurs during embryonic development, post-natal growth, and tissue regeneration. The fundamental cellular basis for tissue growth is the process of cell proliferation, which involves both cell growth and cell division occurring in parallel. How cell proliferation is controlled during tissue growth to determine final tissue size is an open question in biology.
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In general, extracellular growth factors which promote cell division reduce transcription and translation of p27Kip1. Also, increased synthesis of CDk4,6/cyclin D causes binding of p27 to this complex, sequestering it from binding to the CDk2/cyclin E complex. Furthermore, an active CDK2/cyclin E complex will phosphorylate p27 and tag p27 for ubiquitination. A mutation of this gene may lead to loss of control over the cell cycle leading to uncontrolled cellular proliferation.
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The septins were discovered in 1970 by Leland H. Hartwell and colleagues in a screen for temperature-sensitive mutants affecting cell division (cdc mutants) in yeast (Saccharomyces cerevisiae). The screen revealed four mutants which prevented cytokinesis at restrictive temperature. The corresponding genes represent the four original septins, ScCDC3, ScCDC10, ScCDC11, and ScCDC12. Despite disrupted cytokinesis, the cells continued budding, DNA synthesis, and nuclear division, which resulted in large multinucleate cells with multiple, elongated buds.
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In humans, the sites of tissue injury include the jejunum, the ileum, and the colon. Most strains of C jejuni produce cytolethal distending toxin, which inhibits cell division and impedes activation of the immune system. This helps the bacteria to evade the immune system and survive for a limited time inside intestinal cells. A cholera-like enterotoxin was also, at one time, believed to be produced, but this appears not to be the case.
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Removal of Wnt7b activity leads to a failure of medullary development while other aspects of kidney development including ureteric branching, development of the renal cortex, and nephrogenesis are unaffected. The absence of renal medulla also affects the plane of epithelial cell division along with little proliferative growth of the loop of Henle. Wnt7b null allele will result in fatality due to the diminution of placental function leading to the failure to initiate organogenesis.
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However, in Roberts syndrome cell division, the copies are frequently not attached at the centromere. As a result, the chromosomes do not get lined up properly, which causes the cell to divide very slowly or even to not divide at all. The new cells typically will have too many or too few chromosomes. The odd number of chromosomes causes the defective cells to die, which leads to the malformations associated with Roberts syndrome.
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Dynactin is often essential for dynein activity and can be thought of as a "dynein receptor" that modulates binding of dynein to cell organelles which are to be transported along microtubules. Dynactin also enhances the processivity of cytoplasmic dynein and kinesin-2 motors. Dynactin is involved in various processes like chromosome alignment and spindle organization in cell division. Dynactin contributes to mitotic spindle pole focusing through its binding to nuclear mitotic apparatus protein (NuMA).
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Nixon, M. & Messenger, J.B (eds) (1977): The Biology of Cephalopods. Symposium of the Zoological Society of London, pp 38–615 Macrolecithal eggs go through a different type of development than other eggs. Due to the large size of the yolk, the cell division can not split up the yolk mass. The fetus instead develops as a plate-like structure on top of the yolk mass, and only envelopes it at a later stage.
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Divisome and elongasome complexes responsible for peptidoglycan synthesis during lateral cell-wall growth and division. The divisome is a protein complex in bacteria that is responsible for cell division, constriction of inner and outer membranes during division, and peptidoglycan (PG) synthesis at the division site. The divisome is a membrane protein complex with proteins on both sides of the cytoplasmic membrane. In gram-negative cells it is located in the inner membrane.
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The word chromosome () comes from the Greek (chroma, "colour") and (soma, "body"), describing their strong staining by particular dyes. The term was coined by the German scientist von Waldeyer-Hartz, referring to the term chromatin, which was introduced by Walther Flemming, the discoverer of cell division. Some of the early karyological terms have become outdated. For example, Chromatin (Flemming 1880) and Chromosom (Waldeyer 1888), both ascribe color to a non-colored state.
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During most of the cell cycle these are organized in a DNA-protein complex known as chromatin, and during cell division the chromatin can be seen to form the well-defined chromosomes familiar from a karyotype. A small fraction of the cell's genes are located instead in the mitochondria. There are two types of chromatin. Euchromatin is the less compact DNA form, and contains genes that are frequently expressed by the cell.
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The best-characterized members of the family are the FtsW cell division protein, the RodA rod shape determining protein (both of E. coli; TC# 2.A.103.1.2) and the SpoVE protein of B. subtilis (TC# 2.A.103.1.3). They have been shown to function in the translocation (export) of lipid-linked murein precursors such as NAG-NAM- pentapeptide pyrophosphoryl undecaprenol (lipid II). They interact with murein synthases as well as two transpeptidases (PBP2 and PBP3).
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Lipid II was estimated to exist at a concentration of less than 2000 molecules per bacterial cell. Lipid II biosynthesis is functional and essential even in organisms without a cell wall like Chlamydia and Wolbachia. It has been hypothesized that maintaining lipid II biosynthesis reflects its role in prokaryotic cell division. In the discovery and mechanism of assembly of pili in gram positive bacteria Lipid II has been implicated as a crucial structural molecule.
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However, plasmids are not always adapted to their host cell, often resulting in the loss of the plasmid during cell division. In this way, the relative frequency of carriers of this plasmid in a population can decline. However, also in these plasmids mutations can occur, resulting in competition between carriers of the plasmids. Because of this competition, the most stable plasmids will eventually get selected for and their frequency within the population will increase.
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HeLa cells with nuclei (specifically the DNA) stained blue. The central and rightmost cells are in interphase, so the entire nuclei are labeled. The cell on the left is going through mitosis and its DNA has condensed. Cell theory states that the cell is the fundamental unit of life, that all living things are composed of one or more cells, and that all cells arise from pre-existing cells through cell division.
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Gynogenesis is a form of parthenogenesis where an egg begins to divide only after being pricked by a sperm cell, but without the genetic material of the sperm being used. There are two known mechanisms of gynogenesis. The first is an endomitotic event prior to meiosis, where the number of chromosomes in a cell doubles without cell division taking place. After meiosis each egg has the same ploidy (number of chromosomes) as the mother.
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Dithranol accumulates in mitochondria where it interferes with the supply of energy to the cell, probably by the oxidation of dithranol releasing free radicals. This impedes DNA replication and so slows the excessive cell division that occurs in psoriatic plaques. In addition Dithranol may act by reducing the elevated levels of cGMP that occurs in psoriasis. Anthralin is a synthetic compound whose precise mechanism of anti- psoriatic action is not yet fully understood.
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Glypican-4 is a protein that in humans is encoded by the GPC4 gene. Cell surface heparan sulfate proteoglycans are composed of a membrane-associated protein core substituted with a variable number of heparan sulfate chains. Members of the glypican-related integral membrane proteoglycan family (GRIPS) contain a core protein anchored to the cytoplasmic membrane via a glycosyl phosphatidylinositol linkage. These proteins may play a role in the control of cell division and growth regulation.
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In Saccharomyces cerevisiae and the regulation of ScCts1p (S. cerevisiae chitinase 1), one of the chitinases involved in cell separation after cytokinesis by degrading the chitin of the primary septum. As these types of chitinases are important in cell division, there must be tight regulation and activation. Specifically, Cts1 expression has to be activated in daughter cells during late mitosis and the protein has to localize at the daughter site of the septum.
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The prokaryotic cytoskeleton is the collective name for all structural filaments in prokaryotes. It was once thought that prokaryotic cells did not possess cytoskeletons, but recent advances in visualization technology and structure determination have shown that filaments indeed exist in these cells. In fact, homologues for all major cytoskeletal proteins in eukaryotes have been found in prokaryotes. Cytoskeletal elements play essential roles in cell division, protection, shape determination, and polarity determination in various prokaryotes.
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In flowering plants, the sporophyte comprises the whole multicellular body except the pollen and embryo sac Bryophytes (mosses, liverworts and hornworts) have a dominant gametophyte phase on which the adult sporophyte is dependent for nutrition. The embryo sporophyte develops by cell division of the zygote within the female sex organ or archegonium, and in its early development is therefore nurtured by the gametophyte.Ralf Reski(1998): Development, genetics and molecular biology of mosses. In: Botanica Acta.
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The single-stranded DNA was then removed using a single- strand specific DNase under investigation in the Thomas laboratory, leaving the double-stranded gene intact. The elegant electron micrographs of the pre- and post-digested DNA were taken by MacHatty in the Thomas laboratory. Before and following this experiment, Beckwith made important contributions to the study of bacterial genetics. His studies include the mechanisms of protein secretion, disulfide bond formation, and cell division.
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Brinkley has served on numerous journal editorial boards including Journal of Cell Biology and Cell. He briefly served as President of the American Society for Cell Biology (1979–1980). He is the recipient of a Merit Award from the National Institutes of Health, National Cancer Institute, for his research on cell division and genomic instability in tumor cells. He served as President of Federation of American Societies for Experimental Biology from 1998-1999.
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Spindle assembly checkpoint (SAC) abnormalities: The SAC normally delays cell division until all of the chromosomes are accurately attached to the spindle fibers at the kinetochore. Merotelic attachments – when a single kinetochore is connected to microtubules from both spindle poles. Merotelic attachments are not recognized by the SAC, so the cell can attempt to proceed through anaphase. Consequently, the chromatids may lag on the mitotic spindle and not segregate, leading to aneuploidy and chromosome instability.
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Chromosomes duplicate prior to cell division when forming new skin cells for reproduction. After meiotic cell reproduction the four daughter cells have half the number of chromosomes that the parental cell originally had. This is the haploid amount of DNA, often symbolized as N. Meiosis is used by diploid organisms to produce haploid gametes. In a diploid organism such as the human organism, most cells of the body have the diploid amount of DNA, 2N.
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Nemonoxacin is a non-fluorinated quinolone antibiotic undergoing clinical trials. It has the same mechanism of action as fluouroquinolones; it inhibits DNA gyrase, preventing DNA synthesis, gene duplication, and cell division. At the end of 2016, it had reached market in Taiwan, Russia, the Commonwealth Independent States, Turkey, mainland China, and Latin America under the brand name Taigexyn. Nemonoxacin has completed phase 2 trials in the US and has moved on to phase 3 trials.
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The Jak-STAT pathway is instrumental in the development of limbs, specifically in its ability to regulate bone growth through paracrine signaling of cytokines. However, mutations in this pathway have been implicated in severe forms of dwarfism: thanatophoric dysplasia (lethal) and achondroplasic dwarfism (viable). This is due to a mutation in a Fgf gene, causing a premature and constitutive activation of the Stat1 transcription factor. Chondrocyte cell division is prematurely terminated, resulting in lethal dwarfism.
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Glypican-5 is a protein that in humans is encoded by the GPC5 gene. Cell surface heparan sulfate proteoglycans are composed of a membrane-associated protein core substituted with a variable number of heparan sulfate chains. Members of the glypican-related integral membrane proteoglycan family (GRIPS) contain a core protein anchored to the cytoplasmic membrane via a glycosyl phosphatidylinositol linkage. These proteins may play a role in the control of cell division and growth regulation.
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The liver is the main site of transferrin synthesis but other tissues and organs, including the brain, also produce transferrin. A major source of transferrin secretion in the brain is the choroid plexus in the ventricular system. The main role of transferrin is to deliver iron from absorption centers in the duodenum and white blood cell macrophages to all tissues. Transferrin plays a key role in areas where erythropoiesis and active cell division occur.
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For all known substrates, the X amino acid is Alanine, Serine, or Proline. This reaction yields a methylated protein and SAH. Known targets of these methyltransferases in humans include RCC-1 (a regulator of nuclear transport proteins) and Retinoblastoma protein (a tumor suppressor protein that inhibits excessive cell division). RCC-1 methylation is especially important in mitosis as it coordinates the localization of some nuclear proteins in the absence of the nuclear envelope.
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Animation of the structure of a section of DNA. The bases lie horizontally between the two spiraling strands. Nitrogen: blue, oxygen: red, carbon: green, hydrogen: white, phosphorus: orange The Hayflick limit, or Hayflick phenomenon, is the number of times a normal human cell population will divide before cell division stops. The concept of the Hayflick limit was advanced by American anatomist Leonard Hayflick in 1961, at the Wistar Institute in Philadelphia, Pennsylvania, United States.
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Several characteristic genetic changes lead to the creation of a leukemic lymphoblast. These changes include chromosomal translocations, intrachromosomal rearrangements, changes in the number of chromosomes in leukemic cells, and additional mutations in individual genes. Chromosomal translocations involve moving a large region of DNA from one chromosome to another. This move can result in placing a gene from one chromosome that promotes cell division to a more actively transcribed area on another chromosome.
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Turner syndrome is not usually inherited; rather, it occurs during formation of the reproductive cells in a parent or in early cell division during development. No environmental risks are known, and the mother's age does not play a role. Turner syndrome is due to a chromosomal abnormality in which all or part of one of the X chromosomes is missing or altered. While most people have 46 chromosomes, people with TS usually have 45.
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Whereas, disruption of the SPCH (SPeecCHless) gene prevents stomatal development all together. Activation of stomatal production can occur by the activation of EPF1, which activates TMM/ERL, which together activate YODA. YODA inhibits SPCH, causing SPCH activity to decrease, allowing for asymmetrical cell division that initiates stomata formation. Stomatal development is also coordinated by the cellular peptide signal called stomagen, which signals the inhibition of the SPCH, resulting in increased number of stomata.
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Many bacteria reproduce through binary fission, which is compared to mitosis and meiosis in this image. Unlike in multicellular organisms, increases in cell size (cell growth) and reproduction by cell division are tightly linked in unicellular organisms. Bacteria grow to a fixed size and then reproduce through binary fission, a form of asexual reproduction. Under optimal conditions, bacteria can grow and divide extremely rapidly, and bacterial populations can double as quickly as every 9.8 minutes.
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Negative density- dependence, or density-dependent restriction, describes a situation in which population growth is curtailed by crowding, predators and competition. In cell biology, it describes the reduction in cell division. When a cell population reaches a certain density, the amount of required growth factors and nutrients available to each cell becomes insufficient to allow continued cell growth. This is also true for other organisms because an increased density means an increase in intraspecific competition.
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The Ti plasmid is responsible for transmission of crown gall disease in plants infected with A. vitis. Tumorigenic A. vitis transfers its Ti plasmid to other bacteria, and transfers T-DNA into plants. Virulence genes encoded by the Ti plasmid generate single-strand T-DNA molecules, which in turn are transferred to healthy hosts. Disorganized cell division occurs in infected hosts, leading to gall development instead of the formation of healthy vascular tissue.
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Neuroblasts are the progenitor cells which divide asymmetrically to give rise to another neuroblast and a ganglion mother cell (GMC). The neuroblast repeatedly undergoes this asymmetric cell division while the GMC continues on to produce a pair of neurons. Two proteins play an important role in setting up this asymmetry in the neuroblast, Prospero and Numb. These proteins are both synthesized in the neuroblast and segregate into only the GMC during divisions.
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For example, it has been shown that gastrointestinal cancers contain rare subpopulation of cancer stem cells which are capable to divide asymmetrically. The asymmetric division in these cells is regulated by cancer niche (microenvironment) and Wnt pathway. Blocking the Wnt pathway with IWP2 (WNT antagonist) or siRNA-TCF4 resulted in high suppression of asymmetric cell division. Another mutation in asymmetric cell divisions which are involved in tumor growth are loss-of-function mutations.
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It, combined with the Ras pathway, downregulate cyclin D1, a cyclin-dependent kinase if they are not stimulated by the presence of mitogens. In the presence of mitogens, sufficient cyclin D1 can be produced. This process cascades onwards, producing other cyclins which stimulate the cell sufficiently to allow cell division. While animals produce internal signals that can drive the cell cycle forward, external mitogens can cause it to progress without these signals.
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The minichromosome maintenance protein complex (MCM) is a DNA helicase essential for genomic DNA replication. Eukaryotic MCM consists of six gene products, Mcm2–7, which form a heterohexamer. As a critical protein for cell division, MCM is also the target of various checkpoint pathways, such as the S-phase entry and S-phase arrest checkpoints. Both the loading and activation of MCM helicase are strictly regulated and are coupled to cell growth cycles.
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The fusion of the two head-to-head Mcm2-7 hexamers is believed to be facilitated by the removal of Cdt1, leaving the NTDs of the two MCM hexamers flexible for inter-ring interactions. The loading of MCM2-7 onto DNA is an active process that requires ATP hydrolysis by both Orc1-6 and Cdc6. This process is coined "Replication Licensing" as it is a prerequisite for DNA replication initiation in every cell division cycle.
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Alfred Henry Sturtevant (November 21, 1891 - April 5, 1970) was an American geneticist. Sturtevant constructed the first genetic map of a chromosome in 1911. Throughout his career he worked on the organism Drosophila melanogaster with Thomas Hunt Morgan. By watching the development of flies in which the earliest cell division produced two different genomes, he measured the embryonic distance between organs in a unit which is called the sturt in his honor.
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Being pulled in opposite directions will cause the two sister chromatids to break apart from each other, but not necessarily at the site that they fused. This results in the two daughter cells receiving an uneven chromatid. Since the two resulting chromatids lack telomeres, when they replicate the BFB cycle will repeat, and will continue every subsequent cell division until those chromatids receive a telomere, usually from a different chromatid through the process of translocation.
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In phosphatic fossils, the preservation is so fine that even some cellular structure has been preserved. The phosphatic microfossils of the Doushantuo Formation (q.v.), a fossil-rich lagerstätte of the Ediacaran period, about 590–565 Ma (megaannua; million years ago), display some of the most spectacular cellular-level preservation known from the geologic record. The fossils include what may be metazoan blastulas, possibly animal embryos at an early stage in cell division.
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Failure to attach chromosomes to the mitotic apparatus activates the mitotic checkpoint, preventing cells from entering anaphase to proceed with cell division. Agents that disrupt microtubules therefore inhibit mitosis through activation of this checkpoint. Moroidin and its related compounds, the celogentins, inhibit tubulin polymerization. Of this family, celogentin C is the most potent (IC50 0.8×10−6 M), and it is more potent than the anti-mitotic agent vinblastine (IC50 3.0×10−6).
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Studies have shown that the loss of PLK1 expression can induce pro-apoptotic pathways and inhibit growth. Based on yeast and murine studies of meiosis, human PLK1 may also have a regulatory function in meiosis. S. cerevisiae polo kinase CDC5 is required to phosphorylate and remove meiotic cohesion during the first cell division. In CDC5 depleted cells, kinetochores are bioriented during meiosis I, and Mam1, a protein essential for coorientation, fails to associate with kinetochores.
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Before DNA replication, cells contain two centrioles, an older mother centriole, and a younger daughter centriole. During cell division, a new centriole grows at the proximal end of both mother and daughter centrioles. After duplication, the two centriole pairs (the freshly assembled centriole is now a daughter centriole in each pair) will remain attached to each other orthogonally until mitosis. At that point the mother and daughter centrioles separate dependently on an enzyme called separase.
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Halichondria is a genus of sea sponges belonging to the family Halichondriidae.A systematic revision of the central West Atlantic: Halichondrida (Demospongiae, Porifera). Part III: Description of valid species These are massive, amorphous sponges with clearly separated inner and outer skeletons consisting of bundles of spicules arranged in a seemingly random pattern. This genus of sponges became important through the discovery of cell division limiting properties of the extract Halichondrin B, which inhibits cell mitosis.
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Following activation with antigen, B cells begin to proliferate rapidly. In these rapidly dividing cells, the genes encoding the variable domains of the heavy and light chains undergo a high rate of point mutation, by a process called somatic hypermutation (SHM). SHM results in approximately one nucleotide change per variable gene, per cell division. As a consequence, any daughter B cells will acquire slight amino acid differences in the variable domains of their antibody chains.
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In late summer the agamic generation develops in the circular, golden brown, raised, and disc-shaped structure, known as a 'silk button spangle gall'. The gall increase in size even after they fall to the ground in autumn, this being achieved by cell enlargement rather than through further cell division. The gall wasp that causes the agamic generation was previously named as N. vesicator until the two generational status of the species was understood.
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The nematode feeds as an ectoparasite, most often at the site of cell division and elongation of the root (Huang and Becker, 1997). The long stylet allows the nematode to feed on the inner cortex and endodermis. The feeding at root tips causes root abbreviation and stunting (Crow and Han, 2005). In corn roots swelling at root tips may occur due to repeated attempts by the plant to produce new root branches.
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Bicoid has a DNA-binding homeodomain that binds both DNA and the nanos mRNA. Bicoid binds a specific RNA sequence in the 3' untranslated region, called the Bicoid 3'-UTR regulatory element, of caudal mRNA and blocks translation. Hunchback protein levels in the early embryo are significantly augmented by new hunchback gene transcription and translation of the resulting zygotically produced mRNA. During early Drosophila embryogenesis, there are nuclear divisions without cell division.
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Ensembl database, using all 587 genes for EZH2 and the species each gene is found in. Enhancer of zeste (E(z)) was originally identified in Drosophila melanogaster, and its mammalian homologs were subsequently identified and named EZH1 (enhancer of zeste homolog 1) and EZH2 (enhancer of zeste homolog 2). EZH2 is highly conserved through evolution. It and its homologs play essential roles in development, cell differentiation, and cell division in plants, insects, fish, and mammals.
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First, the basal bodies and flagella replicate, then the cytostome and microtubules (the feeding apparatus), and finally the nucleus and remaining cytoskeleton. Once this occurs, the organism begins to cleave at the basal bodies, and this cleavage line moves towards the center of the organism until two separate euglenids are evident. Because of the way that this reproduction takes place and the axis of separation, it is called longitudinal cell division or longitudinal binary fission.
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Cell division control protein 6 homolog is a protein that in humans is encoded by the CDC6 gene. The protein encoded by this gene is highly similar to Saccharomyces cerevisiae Cdc6, a protein essential for the initiation of DNA replication. This protein functions as a regulator at the early steps of DNA replication. It localizes in the cell nucleus during cell cycle phase G1, but translocates to the cytoplasm at the start of S phase.
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It also blocks anchorage-independent colony formation, a hallmark of cancer. This is true whether Pur-alpha is microinjected or expressed after introducing a cloned PURA cDNA into cells. The Pur-alpha inhibition of cancer cell proliferation occurs at specific points in the cell division cycle, primarily at checkpoints for transition to DNA replication or mitosis. These cell cycle effects are consistent with an interaction between Pur-alpha and CDK, cell cycle-dependent protein kinases.
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There are other factors involved in the manifestation of a mitochondrial disease besides the size and location of a mutation. Mitochondria replicate during each cell division during gestation and throughout life. Because the mutation in mitochondrial disease most often occurs early in gestation in these diseases, only those mitochondria in the mutated lineage are defective. This results in an uneven distribution of dysfunctional mitochondria within each cell, and among different tissues of the body.
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Tuberous sclerosis is an autosomal dominant disease in which the genes required to express the tumor-suppressant proteins that form the TSC complex is mutated or missing, so the TSC complex is unable to function properly. This could lead to the disregulation of many signalling proteins and effectors within the cell, including RHEB. Unregulated activity of RHEB can lead to uncontrollable cell growth and cell division which could ultimately lead to formation of tumors.
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Frequency of dividing cells (FDC) is a method used to predict the average growth rate of an aquatic heterotrophic bacterial community. The method uses cell division, specifically septum formation, as a proxy for growth rate. Cells are considered divided, when cavities between individual cells (invagination) are observed under epifluorescence microscopy. FDC is based on the assumption that there relationship between the proportion of cells currently dividing and the growth rate in a bacterial community.
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FANCA mutations have also been implicated in increased risks of cancer and malignancies. For example, patients with homozygous null-mutations in FANCA have a markedly increased susceptibility to acute myeloid leukaemia. Furthermore, as FANC mutations in general affect DNA repair throughout the body and are predisposed to affect dynamic cell division particularly in bone marrow, it is unsurprising that patients are more likely to develop myelodysplastic syndromes (MDS) and acute myeloid leukaemia.
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They have a limited number of divisions before the cells become unable to divide (senescence), or die (crisis). The cause of these barriers is primarily due to the DNA at the end of chromosomes, known as telomeres. Telomeric DNA shortens with every cell division, until it becomes so short it activates senescence, so the cell stops dividing. Cancer cells bypass this barrier by manipulating enzymes (telomerase) to increase the length of telomeres.
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General model for duplication of heterochromatin during cell division Constitutive heterochromatin is replicated late in S phase of the cell cycle and does not participate in meiotic recombination. Histone modifications are one of the main ways that the cell condenses constitutive heterochromatin. The three most common modifications in constitutive heterochromatin are histone hypoacetylation, histone H3-Lys9 methylation (H3K9), and cytosine methylation. These modifications are also found in other types of DNA, but much less frequently.
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The Oedogoniales are an order of filamentous freshwater green algae of the class Chlorophyceae. The order is well-defined and has several unique features, including asexual reproduction with zoospores that possess stephanokont flagella: numerous short flagella arranged in a subapical whorl. The oedogoniales have a highly specialized type of oogamy, and an elaborate method of cell division which results in the accumulation of apical caps. The order comprises one family, Oedogoniaceae, with three genera.
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Neuroblasts undergo three known division types. Type 0 neuroblasts divide to give rise to a neuroblast, and a daughter cell which directly differentiates into a single neuron or glia. Type I neuroblasts give rise to a neuroblast and a ganglion mother cell (GMC), which undergoes a terminal division to generate a pair of sibling neurons. This is the most common form of cell division, and is observed in abdominal, optic lobe, and central brain neuroblasts.
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Other external and internal signals (e.g. blue light, mechanical stress, gravity or cytokinins) can interfere with PIN protein polarity and therefore with the directionality of auxin polar transport. Because auxin controls cell division and cell elongation, the change of PIN proteins localisation, and the subsequent change in auxin distribution, often lead to a change in the growth pattern. For instance, the regulation of polar auxin transport is central in a process such as gravitropism.
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Ras-related protein Ral-A (RalA) is a protein that in humans is encoded by the RALA gene on chromosome 7. This protein is one of two paralogs of the Ral protein, the other being RalB, and part of the Ras GTPase family. RalA functions as a molecular switch to activate a number of biological processes, majorly cell division and transport, via signaling pathways. Its biological role thus implicates it in many cancers.
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The hepatotrophic factor designated augmenter of liver regeneration (ALR) is thought to be one of the factors responsible for the extraordinary regenerative capacity of mammalian liver. It has also been called hepatic regenerative stimulation substance (HSS). The yeast scERV1 gene had been found to be essential for oxidative phosphorylation, the maintenance of mitochondrial genomes, and the cell division cycle. The human gene is both the structural and functional homolog of the yeast scERV1 gene.
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This gene is a member of the septin gene family of nucleotide binding proteins, originally described in yeast as cell division cycle regulatory proteins. Septins are highly conserved in yeast, Drosophila, and mouse and appear to regulate cytoskeletal organization. The protein encoded by this gene is thought to be part of a complex involved in cytokinesis. Alternatively spliced variants which encode different protein isoforms have been described; however, not all variants have been fully characterized.
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Phosphatidylethanolamines are found in all living cells, composing 25% of all phospholipids. In human physiology, they are found particularly in nervous tissue such as the white matter of brain, nerves, neural tissue, and in spinal cord, where they make up 45% of all phospholipids. Phosphatidylethanolamines play a role in membrane fusion and in disassembly of the contractile ring during cytokinesis in cell division. Additionally, it is thought that phosphatidylethanolamine regulates membrane curvature.
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This study produces a series of descriptions of how the notochordal canal develops and some implications based on its development. In the latter study, samples of Sargatia were taken from Cold Spring Harbor and examined in a laboratory. Under a microscope, the sea anemones' cell division was examined in both natural conditions and artificially placed strain. During and after the division processes, the various stripe characteristics were noted and recorded from different samples.
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Mutations in the ATM gene cause ataxia–telangiectasia. The ATM gene provides instructions for making a protein that helps control cell division and is involved in DNA repair. This protein plays an important role in the normal development and activity of several body systems, including the nervous system and immune system. The ATM protein assists cells in recognizing damaged or broken DNA strands and coordinates DNA repair by activating enzymes that fix the broken strands.
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Stathmin, also known as metablastin and oncoprotein 18 is a protein that in humans is encoded by the STMN1 gene. Stathmin is a highly conserved 17 kDa protein that is crucial for the regulation of the cell cytoskeleton. Changes in the cytoskeleton are important because the cytoskeleton is a scaffold required for many cellular processes, such as cytoplasmic organization, cell division and cell motility. More specifically, stathmin is crucial in regulating the cell cycle.
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The function of septins in cells include serving as a localized attachment site for other proteins, and preventing the diffusion of certain molecules from one cell compartment to another. In yeast cells, they build scaffolding to provide structural support during cell division and compartmentalize parts of the cell. Recent research in human cells suggests that septins build cages around bacterial pathogens, immobilizing the harmful microbes and preventing them from invading other cells.
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First fic gene was discovered in the late 1980s in Escherichia coli. Mutation in this gene impaired cell division under stress conditions (cyclic AMP in growth medium at high temperature), which led to annotation as fic-1 for filamentation induced by cAMP. The product of fic-1 was later characterized as toxin from toxin-antitoxin system. Fic domain protein from the Vibrio parahaemolyticus VopS is a toxin secreted by type III secretion system.
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Ras-related protein Ral-B (RalB) is a protein that in humans is encoded by the RALB gene on chromosome 2. This protein is one of two paralogs of the Ral protein, the other being RalA, and part of the Ras GTPase family. RalA functions as a molecular switch to activate a number of biological processes, majorly cell division and transport, via signaling pathways. Its biological role thus implicates it in many cancers.
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C. meneghiniana splits in half during asexual reproduction. The halves are separated by the distinction between the two valves for each cell. Each of the two offspring that arise as a result of cell division have one of the two valves from the parent cell. During the separation of the parent cell, the cytoplasm forms the two offspring valves that will end up complementing the inherited parent valves in the offspring once reproduction is complete.
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It is important in maintaining basic cellular functions such as DNA replication, RNA transcription, cell division and cell activations. However, having too much or too little zinc can cause these functions to be compromised. Zinc is a critical component of the catalytic site of hundreds of kinds of different metalloenzymes in each human being. In its structural role, zinc coordinates with certain protein domains, facilitating protein folding and producing structures such as 'zinc fingers'.
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BRAF V600E gene and SMO gene mutations have been found in ameloblastomas. V600E mutation is also seen in other malignant and benign neoplasms, which activate the MAP kinase pathway required for cell division and differentiation but is the most commonly seen mutation in ameloblastoma. 72% of BRAF mutations are found in the mandible. A recent study discovered a high frequency of BRAF V600E mutations (15 of 24 samples, 63%) in conventional ameloblastoma.
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It is at this rounding stage that the decision on the orientation of the cell division is made by the spindle apparatus. The spindle apparatus then rotates in the round cell and after several minutes the spindle position is stabilised preferentially along the interphase cell long axis. The cell then divides along the spindle apparatus orientation. The first insights into how cells could remember their long axis came from studies on the Drosophila epithelium.
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Cell division involves a single cell (called a mother cell) dividing into two daughter cells. This leads to growth in multicellular organisms (the growth of tissue) and to procreation (vegetative reproduction) in unicellular organisms. Prokaryotic cells divide by binary fission, while eukaryotic cells usually undergo a process of nuclear division, called mitosis, followed by division of the cell, called cytokinesis. A diploid cell may also undergo meiosis to produce haploid cells, usually four.
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Uniquely, streptophyte cells and those of the green algal order Trentepohliales divide by construction of a phragmoplast as a template for building a cell plate late in cell division. The bodies of vascular plants including clubmosses, ferns and seed plants (gymnosperms and angiosperms) generally have aerial and subterranean subsystems. The shoots consist of stems bearing green photosynthesising leaves and reproductive structures. The underground vascularised roots bear root hairs at their tips and generally lack chlorophyll.
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Monocentric organisms, including vertebrates, fungi, and most plants, have a single centromeric region on each chromosome which assembles a single, localized kinetochore. Holocentric organisms, such as nematodes and some plants, assemble a kinetochore along the entire length of a chromosome. Kinetochores start, control, and supervise the striking movements of chromosomes during cell division. During mitosis, which occurs after chromosomes are duplicated in S phase, two sister chromatids are held together by a centromere.
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An autospore is defined one of the daughter cells formed by the internal division of a single cell. Autospores are formed as a result of fission in the mitotic phase of cell division of green algae. There are multiple methods that a cell can take to form autospores. The cell can undergo a multiple fission after 2 nuclear divisions where 4 autospores will form which is the preferred mechanism in organisms such as P. subcapitata.
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Those sequences, located at the end of the telomere and chromosome, would hence get lost gradually. Once all of these sequences have been worn out, the useful genetic information in the cell’s chromosome would also get lost. This prevents cells from cell dividing, withdrawing cells from the cell division cycle. Therefore telomeres act as the buffer for cells to continue dividing and when telomeres are worn out, cells lose their dividing function.
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There are different classes of drugs directed against thymidine metabolism and thereby involving thymidine kinase that are used to control cancer associated cell division. Chain terminators are thymidine analogues that are included in the growing DNA chain, but modified so that the chain cannot be further elongated. As analogs of thymidine, this type of drugs are readily phosphorylated to 5'-monophosphates. The monophosphate is further phosphorylated to the corresponding triphosphate and incorporated in the growing DNA chain.
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At the beginning of preprophase, the cortical microtubules of a plant cell disappear and aggregate into a dense ring underneath the plasma membrane. This preprophase band runs around the equatorial plane of the future mitotic spindle and marks the plane of cell division and future fusion site for the cell plate. It consists of microtubules and microfilaments (actin) and persists into prophase. Spindle formation occurs during prophase with the axis perpendicular to the plane surrounded by the preprophase band.
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He used cell polarisation methods to understand the changes in molecular organisation of the mitotic spindle. With his collaborator Murdoch Mitchison, he found evidence in support of a new theory of cell division. He collaborated with Victor Rothschild in experiments on changes in membrane structure during fertilisation. From 1965 to 1974, he was the Principal and Vice-Chancellor of Edinburgh University. In 1968, he was awarded an honorary Doctorate of Science by the University of Leicester.
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Several discoveries have been made that have led to greater understandings and perhaps eventual treatment for this disease. A 2003 report in Nature said that progeria may be a de novo dominant trait. It develops during cell division in a newly conceived zygote or in the gametes of one of the parents. It is caused by mutations in the LMNA (lamin A protein) gene on chromosome 1; the mutated form of lamin A is commonly known as progerin.
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However, in the first meiotic division the sister chromatids are held together by cohesins and segregated from their homologous pair of cohesion bound sister chromatids after resolution of recombination crossover points (chiasma) between the homologous pairs. The collision of mitosis and meiosis (first division) pathways could cause abnormal chiasma formation, abnormal cohesion expression, and mitotic/meiotic spindle defects that could result in insertions, deletions, abnormal segregation, DNA bridging, and potentially failure of cell division altogether resulting in polyploidy.
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Factors such as the chemistry of the environment may have been responsible for changes. While prokaryotic cyanobacteria themselves reproduce asexually through cell division, they were instrumental in priming the environment for the evolutionary development of more complex eukaryotic organisms. Cyanobacteria (as well as extremophile Gammaproteobacteria) are thought to be largely responsible for increasing the amount of oxygen in the primeval earth's atmosphere through their continuing photosynthesis. Cyanobacteria use water, carbon dioxide and sunlight to create their food.
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An acentric fragment is a segment of a chromosome that lacks a centromere.Acentric Fragment, In: Sydney Brenner and Jeffrey H. Miller, Editor(s)-in-Chief, Encyclopedia of Genetics, Academic Press, New York, 2001, Page 2, , 10.1006/rwgn.2001.1750. Because the centromere is the point of attachment for the mitotic apparatus, acentric fragments are not evenly distributed to the daughter cells in cell division (mitosis and meiosis). As a result, one of the daughters will lack the acentric fragment.
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1\. Shows a plant lacking gibberellins and has an internode length of "0" as well as it is a dwarf plant. 2. Shows your average plant with a moderate amount of gibberellins and an average internode length. 3.Shows a plant with a large amount of gibberellins and so has a much longer internode length because gibberellins promotes cell division in the stem.Gibberellins are involved in the natural process of breaking dormancy and other aspects of germination.
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In Cooperation with Karl Welte and his colleagues at MSKCC the purification and molecular and biological characterization of cytokines, important regulators of cell division, differentiation and migration, were the focus of his work in the following years at MSKCC. Interleukin-2K. Welte, C. Y. Wang, R. Mertelsmann, S. Venuta, S. P. Feldman, M. A. Moore: Purification of human interleukin 2 to apparent homogeneity and its molecular heterogeneity. In: J Exp Med. 1982 Aug 1;156(2), S. 454–464.
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The life cycle of T. thermophila consists of an alternation between asexual and sexual stages. In nutrient rich media during vegetative growth cells reproduce asexually by binary fission. This type of cell division occurs by a sequence of morphogenetic events that results in the development of duplicate sets of cell structures, one for each daughter cell. Only during starvation conditions will cells commit to sexual conjugation, pairing and fusing with a cell of opposite mating type.
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In vitro, when cells approach the Hayflick limit, the time to senescence can be extended by inactivating the tumor suppressor proteins - p53 and Retinoblastoma protein (pRb). Cells that have been so- altered eventually undergo an event termed a "crisis" when the majority of the cells in the culture die. Sometimes, a cell does not stop dividing once it reaches a crisis. In a typical situation, the telomeres are shortened and chromosomal integrity declines with every subsequent cell division.
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Exposed chromosome ends are interpreted as double-stranded breaks (DSB) in DNA; such damage is usually repaired by reattaching (relegating) the broken ends together. When the cell does this due to telomere-shortening, the ends of different chromosomes can be attached to each other. This solves the problem of lacking telomeres, but during cell division anaphase, the fused chromosomes are randomly ripped apart, causing many mutations and chromosomal abnormalities. As this process continues, the cell's genome becomes unstable.
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It has been proposed that the swift rise of angiosperms to dominance was facilitated by a reduction in their genome size. During the early Cretaceous period, only angiosperms underwent rapid genome downsizing, while genome sizes of ferns and gymnosperms remained unchanged. Smaller genomes—and smaller nuclei—allow for faster rates of cell division and smaller cells. Thus, species with smaller genomes can pack more, smaller cells—in particular veins and stomata—into a given leaf volume.
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Actin participates in many important cellular processes, including muscle contraction, cell motility, cell division and cytokinesis, vesicle and organelle movement, cell signaling, and the establishment and maintenance of cell junctions and cell shape. Many of these processes are mediated by extensive and intimate interactions of actin with cellular membranes. In vertebrates, three main groups of actin isoforms, alpha, beta, and gamma have been identified. The alpha actins, found in muscle tissues, are a major constituent of the contractile apparatus.
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While prokaryotic cyanobacteria reproduce asexually through cell division, they were instrumental in priming the environment for the evolutionary development of more complex eukaryotic organisms. Cyanobacteria (as well as extremophile Gammaproteobacteria) are thought to be largely responsible for increasing the amount of oxygen in the primeval earth's atmosphere through their continuing photosynthesis (see Great Oxygenation Event). Cyanobacteria use water, carbon dioxide, and sunlight to create their food. A layer of mucus often forms over mats of cyanobacterial cells.
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Most of these are synthesized by the ribosomes through an enzyme- catalyzed process called protein biosynthesis. A sequence of amino acids is assembled and joined together based upon gene expression of the cell's nucleic acid. In eukaryotic cells, these proteins may then be transported and processed through the Golgi apparatus in preparation for dispatch to their destination. Cells reproduce through a process of cell division in which the parent cell divides into two or more daughter cells.
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Hence, boron deficiency diseases appear in dry weather. Boron has many functions within a plant: it affects flowering and fruiting, pollen germination, cell division, and active salt absorption. The metabolism of amino acids and proteins, carbohydrates, calcium, and water are strongly affected by boron. Many of those listed functions may be embodied by its function in moving the highly polar sugars through cell membranes by reducing their polarity and hence the energy needed to pass the sugar.
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Cdc4 (cell division control protein 4) is a substrate recognition component of the SCF (SKP1-CUL1-F-box protein) ubiquitin ligase complex, which acts as a mediator of ubiquitin transfer to target proteins, leading to their subsequent degradation via the ubiquitin-proteasome pathway. Cdc4 targets primarily cell cycle regulators for proteolysis. It serves the function of an adaptor that brings target molecules to the core SCF complex. Cdc4 was originally identified in the model organism Saccharomyces cerevisiae.
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IAPs like survivin, inhibit apoptosis by physically binding to and inhibiting proper caspase function. The function of IAPs is evolutionarily conserved as Drosophila homologues of IAPs have been shown to be essential for cell survival. IAPs have been implicated in studies to have a regulatory effect on cell division. Yeast cells with knock-outs of certain IAP genes did not show problems associated with cell death, but showed defects in mitosis characterized by improper chromosome segregation or failed cytokinesis.
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The APC protein accomplishes these tasks mainly through association with other proteins, especially those that are involved in cell attachment and signaling. The activity of one protein in particular, beta-catenin, is controlled by the APC protein (see: Wnt signaling pathway). Regulation of beta-catenin prevents genes that stimulate cell division from being turned on too often and prevents cell overgrowth. The human APC gene is located on the long (q) arm of chromosome 5 in band q22.2 (5q22.2).
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They involve in the regulation of a variety of cellular processes, such as cell division, glycogen metabolism, muscle contractility, protein synthesis, and HIV-1 viral transcription. PSME3 facilitates the MDM2-p53/TP53 interaction which promotes ubiquitination- and MDM2-dependent proteasomal degradation of p53/TP53, limiting its accumulation and resulting in inhibited apoptosis after DNA damage, and might play a role in cell cycle regulation. RBFOX2 regulates alternative splicing events by binding to 5'-UGCAUGU-3' elements.
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The first hint that led to the discovery of the SCF complex came from genetic screens of Saccharomyces cerevisiae, also known as budding yeast. Temperature-sensitive cell division cycle (Cdc) mutants—such as Cdc4, Cdc34, and Cdc53—arrested in G1 with unreplicated DNA and multiple elongated buds. The phenotype was attributed to a failure to degrade Sic1, an inhibitor of S cyclin-CDK complexes. These findings indicated that proteolysis is important in the G1/S transition.
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An extrachromosomal array is a method for mosaic analysis in genetics. It is a cosmid, and contains two functioning (wild-type) closely linked genes: a gene of interest and a mosaic marker. Such an array is injected into germ line cells, which already contain mutant (specifically, loss of function) alleles of all three genes in their chromosomal DNA. The cosmid, which is not packed correctly during mitosis, is occasionally present in only one daughter cell following cell division.
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In species of algae that contain a single chloroplast, regulation of chloroplast division is extremely important to ensure that each daughter cell receives a chloroplast—chloroplasts can't be made from scratch. In organisms like plants, whose cells contain multiple chloroplasts, coordination is looser and less important. It is likely that chloroplast and cell division are somewhat synchronized, though the mechanisms for it are mostly unknown. Light has been shown to be a requirement for chloroplast division.
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Kleptogenic reproduction results in three potential outcomes. A unisexual female may simply activate cell division in the egg through the presence of a male's sperm without incorporating any of his genetic material—this results in the production of clonal offspring. The female may also incorporate the male's sperm into her egg, but can do so without excising any of her genetic material. This results in increased ploidy levels that range from triploid to pentaploid in wild individuals.
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MAP/microtubule affinity-regulating kinase 4 is an enzyme that in humans is encoded by the MARK4 gene. MARK4 belongs to the family of serine/threonine kinases that phosphorylate microtubule-associated proteins (MAP) causing their detachment from microtubules. Detachment thereby increases microtubule dynamics and facilitates a number of cell activities including cell division, cell cycle control, cell polarity determination, and cell shape alterations. There are four members of the MARK protein family, MARK1-4, which are highly conserved.
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Erythrocytes mature through erythropoiesis in the bone marrow, where they lose their nuclei, organelles, and ribosomes. The nucleus is expelled during the process of differentiation from an erythroblast to a reticulocyte, which is the immediate precursor of the mature erythrocyte. The presence of mutagens may induce the release of some immature "micronucleated" erythrocytes into the bloodstream. Anucleated cells can also arise from flawed cell division in which one daughter lacks a nucleus and the other has two nuclei.
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A bacterial artificial chromosome (BAC) is a DNA construct, based on a functional fertility plasmid (or F-plasmid), used for transforming and cloning in bacteria, usually E. coli. F-plasmids play a crucial role because they contain partition genes that promote the even distribution of plasmids after bacterial cell division. The bacterial artificial chromosome's usual insert size is 150–350 kbp. A similar cloning vector called a PAC has also been produced from the DNA of P1 bacteriophage.
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However, cannas have a reputation for being difficult micropropagation candidates. Micropropagation techniques can be employed to disinfest plants of a virus. In the growing tip of a plant, cell division is so rapid that the younger cells may not have had time to be infected with the virus. The rapidly growing region of meristem cells producing the shoot tip is cut off and placed in vitro, with a very high probability of being uncontaminated by virus.
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The Venus Flytrap (Dionaea muscipula) presents a spectacular example of thigmonasty; when an insect lands on a trap formed by two curved lobes of a single leaf, the trap rapidly switches from an open to a closed configuration. Investigators have observed an action potential and changes in leaf turgor that accompany the reflex; they trigger the rapid elongation of individual cells. The common term for the elongation is acid growth although the process does not involve cell division.
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DNA methylation can be stable during cell division, allowing for methylation states to be passed to other orthologous genes in a genome. DNA methylation can be reversed via the use of enzymes known as DNA de-methylases, while histone modifications can be reversed via removing histone acetyl groups with deacetylases. Interspecific differences due to environmental factors are shown to be associated with the difference between annual and perennial life cycles. There can be varying adaptive responses based on this.
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It reveals many cellular structures that are invisible with a bright-field microscope, as exemplified in the figure. These structures were made visible to earlier microscopists by staining, but this required additional preparation and death of the cells. The phase- contrast microscope made it possible for biologists to study living cells and how they proliferate through cell division. It is one of the few methods available to quantify cellular structure and components that does not use fluorescence.
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Ubiquitin carboxyl-terminal hydrolase 16 is an enzyme that in humans is encoded by the USP16 gene. This gene encodes a deubiquitinating enzyme that is phosphorylated at the onset of mitosis and then dephosphorylated at the metaphase/anaphase transition. It can deubiquitinate H2A, one of two major ubiquitinated proteins of chromatin, in vitro and a mutant form of the protein was shown to block cell division. Alternate transcriptional splice variants, encoding different isoforms, have been characterized.
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PRC1 dimers, required for the high-affinity interaction with Kinesin-4, recruit Kinesin-4 to regions of antiparallel microtubule overlap, where Kinesin-4, a plus-end directed motor protein that inhibits microtubule dynamics, helps to form length-dependent end tags that help stabilize and regulate spindle microtubule assembly within cytokinesis. This PRC1-Kinesin-4 complex differentially identifies and regulates the spindle midzone microtubules during cell division. This regulation is crucial in order for cytokinesis to progress properly.
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Chromosome mutation was formerly used in a strict sense to mean a change in a chromosomal segment, involving more than one gene. The term "karyotype" refers to the full set of chromosomes from an individual; this can be compared to a "normal" karyotype for the species via genetic testing. A chromosome anomaly may be detected or confirmed in this manner. Chromosome anomalies usually occur when there is an error in cell division following meiosis or mitosis.
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RpoS-dependent genes involved in changes in cell membrane permeability and general cell morphology mostly belong to the osm family of genes. osmB encodes an outer membrane lipoprotein that may play a role in cell aggregation (Jung et al., 1990) , whereas osmY encodes a periplasmic protein. Additional RpoS-dependent factors that determine the size and shape of the cell include the morphogene bolA and products of the ftsQAZ operon that play a role in the timing of cell division .
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They named this cell division gene ftsZ. In 1991 Bi and Lutkenhaus used immunogold electron microscopy to show that FtsZ localized to the invaginating septum at midcell. Subsequently, the Losick and Margolin groups used immuno- fluorescence microscopy and GFP fusions to show that FtsZ assembled Z rings early in the cell cycle, well before the septum began to constrict. Other division proteins then assemble onto the Z ring and constriction occurs in the last part of the cell cycle.
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The microtubule-organizing center (MTOC) is a structure found in eukaryotic cells from which microtubules emerge. MTOCs have two main functions: the organization of eukaryotic flagella and cilia and the organization of the mitotic and meiotic spindle apparatus, which separate the chromosomes during cell division. The MTOC is a major site of microtubule nucleation and can be visualized in cells by immunohistochemical detection of γ-tubulin. The morphological characteristics of MTOCs vary between the different phyla and kingdoms.
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Sue Biggins (born 1968) is an American cell biologist who studies kinetochores and the transfer of chromosomes during cell division. Her team isolated kinetochores from cells, enabling them to be studied separately under laboratory conditions. They also discovered that tension helps kinetochores to attach to microtubules and move from the mother cell to the daughter cells when cells divide. The methodology and concepts she developed for yeast kinetochores are being adopted in laboratories around the world.
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Dunder contains many by-products that help in future fermentations, including dead yeast cells, which are an excellent yeast nutrient. Subsequent fermentations using dunder must be carefully controlled to prevent stress on the yeast which will cause a greater amount of mutations. Also if planning to store dunder before use it is advised to refrigerate the dunder to suppress cell division as to prevent mutations. These mutations change flavor, alcohol content, and overall affect consistency of the finished product.
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In recent years, it has been found that microtubule-based molecular motors (including a number of kinesins) have a role in mitosis (cell division). Kinesins are important for proper spindle length and are involved in sliding microtubules apart within the spindle during prometaphase and metaphase, as well as depolymerizing microtubule minus ends at centrosomes during anaphase. Specifically, Kinesin-5 family proteins act within the spindle to slide microtubules apart, while the Kinesin 13 family act to depolymerize microtubules.
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The localization of RAD51 to the DNA double- strand break requires the formation of the BRCA1-PALB2-BRCA2 complex. PALB2 (Partner and localizer of BRCA2) can function synergistically with a BRCA2 chimera (termed piccolo, or piBRCA2) to further promote strand invasion. These breaks can be caused by natural and medical radiation or other environmental exposures, but also occur when chromosomes exchange genetic material during a special type of cell division that creates sperm and eggs (meiosis).
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The farther a place is from the equator, the less UVB is received, and the potential to produce of vitamin D is diminished. Some regions far from the equator do not receive UVB radiation at all between autumn and spring. Vitamin D deficiency does not kill its victims quickly, and generally does not kill at all. Rather it weakens the immune system, the bones, and compromises the body’s ability to fight uncontrolled cell division which results in cancer.
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For example, an oocyte or sperm cell may gain an extra copy of the X chromosome as a result of the non-disjunction. If one of these cells contributes to the genetic makeup of a child, the child will have an extra X chromosome in each of her cells. In some cases, trisomy X occurs during cell division in early embryonic development. Some females with triple X syndrome have an extra X chromosome in only some of their cells.
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Many of the tumors derive from one (sufficiently) mutated cell, so they are technically a single clone of cells. However, during course of cell division, one of the cells can get mutated further and acquire new characteristics to diverge as a new clone. However, this view of cancer onset has been challenged in recent years and many tumors have been argued to have polyclonal origin, i.e. derived from two or more cells or clones, including malignant mesothelioma.
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Ruderfer et al. pointed out that, in nature, such contacts are frequent between closely related yeast cells for two reasons. The first is that cells of opposite mating type are present together in the same acus, the sac that contains the cells directly produced by a single meiosis, and these cells can mate with each other. The second reason is that haploid cells of one mating type, upon cell division, often produce cells of the opposite mating type.
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Transcription termination factor 2 is a protein that in humans is encoded by the TTF2 gene. This gene encodes a member of the SWI2/SNF2 family of proteins, which play a critical role in altering protein-DNA interactions. The encoded protein has been shown to have dsDNA-dependent ATPase activity and RNA polymerase II termination activity. This protein interacts with cell division cycle 5-like, associates with human splicing complexes, and plays a role in pre-mRNA splicing.
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Auxesis (from the Greek word meaning increase; grow) refers to growth from an increase in cell size rather than an increase in the number of cells. Auxetic growth occurs in certain tissues, such as muscle, of the higher animals as well as in some organisms, such as nematodes, tunicates, and rotifers.Types of Growth: Auxetic Growth, Tutor Vista In plant physiology, an auxetic substance will tend to increase cell growth without any cell division. Auxins are auxetic plant hormones.
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Ubiquitin-activating enzymes, also known as E1 enzymes, catalyze the first step in the ubiquitination reaction, which (among other things) can target a protein for degradation via a proteasome. This covalent bond of ubiquitin or ubiquitin-like proteins to targeted proteins is a major mechanism for regulating protein function in eukaryotic organisms. Many processes such as cell division, immune responses and embryonic development are also regulated by post-translational modification by ubiquitin and ubiquitin-like proteins.
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The blastocyst has a diameter of about 0.1–0.2 mm and comprises 200–300 cells following rapid cleavage (cell division). About seven days after fertilization, the blastocyst undergoes implantation, embedding into the endometrium of the uterine wall. There it will undergo further developmental processes, including gastrulation. Embedding of the blastocyst into the endometrium requires that it hatches from the zona pellucida, which prevents adherence to the fallopian tube as the pre-embryo makes its way to the uterus.
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Intracellular and extracellular signals within the cell highly regulate when and which proteins are tagged with ubiquitin. Once attached to the protein, ubiquitin serves as a signaling molecule to the proteasomes, which then bind to the ubiquinated proteins and degrades them. This ubiquitin-proteasome system acts as the cell's quality control system by breaking down unwanted proteins. Additionally, the system regulates the level of proteins involved in critical cell activities such as the timing of cell division and growth.
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ESCs divide very frequently due to a shortened G1 phase in their cell cycle. Rapid cell division allows the cells to quickly grow in number, but not size, which is important for early embryo development. In ESCs, cyclin A and cyclin E proteins involved in the G1/S transition are always expressed at high levels. Cyclin-dependent kinases such as CDK2 that promote cell cycle progression are overactive, in part due to downregulation of their inhibitors.
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In non-dividing cells, these concatemers remain intact for the life of the host cell. In dividing cells, AAV DNA is lost through cell division, since the episomal DNA is not replicated along with the host cell DNA. Random integration of AAV DNA into the host genome is detectable but occurs at very low frequency. AAVs also present very low immunogenicity, seemingly restricted to generation of neutralizing antibodies, while they induce no clearly defined cytotoxic response.
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Although one can inherit 13q deletion syndrome, the most common way to obtain the disease is through genetic mutations. All human chromosomes have 2 arms, the p (short) arm and the q (long) arm. They are separated from each other only by a primary constriction, the centromere, the point at which the chromosome is attached to the spindle during cell division. When portions of the long arm of chromosome 13 are altered during gametogenesis, 13q deletion syndrome results.
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Heilmann (1926) pp. 64–65. Following an analysis of the germ cells, he moves onward through the developmental cycle by next examining the process of fertilization and subsequent cleavage of the zygote. He presents here several figures and illustrations of the cleavage of the blastoderm in reptiles and birds. He examines in detail the expression of evolutionary stages in the development of embryos, tracing from the process of cell division to the development of specific anatomical features.
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Prasinococcus have a firm cell wall lacking scales and also lack flagella. The mitochondrial lobe and chloroplast outer membrane both protrude into the pyrenoid matrix which is considered characteristic of the genus. The cell wall has a protruding circular collar which is surrounded by holes which penetrate the cell wall. Its method of asexual reproduction is also considered characteristic - after cell division one daughter cell remains within the original cell wall while the other is extruded.
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The still ubiquitous role of thermal cycling in germination and cell division is considered a relic of primordial thermosynthesis. By phosphorylating cell membrane lipids, this first protein gave a selective advantage to the lipid protocell that contained the protein. This protein also synthesized a library of many proteins, of which only a minute fraction had thermosynthesis capabilities. As proposed by Dyson, it propagated functionally: it made daughters with similar capabilities, but it did not copy itself.
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Blooms have been noted in contaminated environments due to excess augmentation of ammonia from industrial waste and are now being associated with the drop in biodiversity in such water bodies. Both sexual and asexual reproduction are possible for species within this genus. In addition, mitosis is well defined in Tetraspora species; particularly investigated in T. gelatinosa. Cell division involves elaborate arrangement of microtubules, basal body complexes and involve the use of structures like phycoplasts and protoplast.
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Cell division in Tetraspora species has been described. It is noted that prior to mitosis beginning, cells become immotile and the basal bodies located at the surface of cells start to retreat in. This causes the preprophase nucleus to migrate toward retreating basal body complex, around which microtubules start to gather. The basal body complex arranges itself to be closely associated with one pole of the cell, creating a mitotic spindle known as open polar fenestrae.
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Conceptualization of p53 pathway. p53-DNA damage complex Between G1 and S phase, three DNA damage checkpoints occur to ensure proper growth and synthesis of DNA prior to cell division. Damaged DNA during G1, before entry into S phase, and during S phase result in the expression of ATM/R protein. ATM/R protein then stabilizes and activates transcription factor p53 so that it can bind to upstream regions of genes, inducing the expression of proteins including p21CIP.
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Injaz was created from ovarian cells of an adult camel slaughtered for its meat in 2005. The cells were grown in tissue culture and then frozen in liquid nitrogen. Afterwards, one of the cells was injected into a nucleus-removed oocyte of the surrogate camel, which were then fused with an electric current and chemically induced to initiate cell division. The resulting embryo was cultured for a week and implanted back into the surrogate camel's uterus.
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The remnants of the megasporangium tissue (the nucellus) surround the megagametophyte. Megagametophytes produce archegonia (lost in some groups such as flowering plants), which produce egg cells. After fertilization, the ovule contains a diploid zygote and then, after cell division begins, an embryo of the next sporophyte generation. In flowering plants, a second sperm nucleus fuses with other nuclei in the megagametophyte forming a typically polyploid (often triploid) endosperm tissue, which serves as nourishment for the young sporophyte.
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They are highly dynamic—they circulate and are moved around within plant cells, and occasionally pinch in two to reproduce. Their behavior is strongly influenced by environmental factors like light color and intensity. Chloroplasts, like mitochondria, contain their own DNA, which is thought to be inherited from their ancestor—a photosynthetic cyanobacterium that was engulfed by an early eukaryotic cell. Chloroplasts cannot be made by the plant cell and must be inherited by each daughter cell during cell division.
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In one, the daughter cells are initially equivalent but a difference is induced by signaling between the cells, from surrounding cells, or from the precursor cell. This mechanism is known as extrinsic asymmetric cell division. In the second mechanism, the prospective daughter cells are inherently different at the time of division of the mother cell. Because this latter mechanism does not depend on interactions of cells with each other or with their environment, it must rely on intrinsic asymmetry.
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Folate is required for cell division, and rapidly dividing cancer cells often express folate receptors in order to capture enough folate to support rapid cell growth. Elevated expression of the folate receptor occurs in many diseases, including other aggressively growing cancers and inflammatory disorders. Vintafolide binds to the folate receptor and is subsequently taken up by the cell through a natural internalization process called endocytosis. Once inside the cell, vintafolide’s linker releases the chemotherapy drug which kills the cell.
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His work looks at specialised structures known as kinetochores and the mechanisms which monitor the correct attachment of microtubules to the chromosomes. Tomo Tanaka studies the processes by which eukaryotic cells maintain their genetic integrity. His group use budding yeast to study chromosome duplication and segregation. By understanding the processes that occur during cell division, it is hoped that a better knowledge will be gained of human diseases such as cancer which are often characterised by chromosome instability.
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To ensure the proper replication of cellular components and division, there are control mechanisms known as cell cycle checkpoints after each of the key steps of the cycle that determine if the cell can progress to the next phase. In cells without nuclei (prokaryotes), (i.e., bacteria and archaea), the cell cycle is divided into the B, C, and D periods. The B period extends from the end of cell division to the beginning of DNA replication.
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Leech embryogenesis is the process by which the embryo of the leech forms and develops. The embryonic development of the larva occurs as a series of stages. During stage 1, the first cleavage occurs, which gives rise to an AB and a CD blastomere, and is in the interphase of this cell division when a yolk-free cytoplasm called teloplasm is formed. The teloplasm is known to be a determinant for the specification of the D cell fate.
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Clb5 and Clb6 levels are high at the beginning of S-phase, though they initially rise in G1. Upon commitment to cell division, G1/S cyclin levels rise, bind Cdk1, and immediately form active complexes. Clb5 and Clb6 are also expressed and bind Cdk1, but are inactive based on control from the Clb-specific Cdk1 inhibitor Sic1. G1/S cyclin-Cdk complexes promote the destruction of Sic1 and allow activation of Clb5- and Clb6-Cdk1 complexes.
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Mitogens can be either endogenous or exogenous factors. Endogenous mitogens function to control cell division is a normal and necessary part of the life cycle of multicellular organisms. For example, in zebrafish, an endogenous mitogen Nrg1 is produced in response to indications of heart damage. When it is expressed, it causes the outer layers of the heart to respond by increasing division rates and producing new layers of heart muscle cells to replace the damaged ones.
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Regardless, it is clear that RAD9 is necessary to sense DNA damage and halt cell division. RAD9 has been suggested to possess 3’ to 5’ exonuclease activity, which is perhaps why it plays a role in detecting DNA damage. When DNA is damaged, it is hypothesized that RAD9 forms a complex with RAD1 and HUS1, and this complex is recruited to sites of DNA damage. It is in this way that RAD9 is able to exert its effects.
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People who inherit only one functional copy of the TP53 gene will most likely develop tumors in early adulthood, a disorder known as Li-Fraumeni syndrome. The TP53 gene can also be modified by mutagens (chemicals, radiation, or viruses), increasing the likelihood for uncontrolled cell division. More than 50 percent of human tumors contain a mutation or deletion of the TP53 gene. Loss of p53 creates genomic instability that most often results in an aneuploidy phenotype.
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Embedded in the conjunctive tissue of the mantle, these cells may survive and form a small pocket in which they continue to secrete calcium carbonate, their natural product. The pocket is called a pearl sac, and grows with time by cell division. The juvenile mantle tissue cells, according to their stage of growth, secrete columnar calcium carbonate from pearl sac's inner surface. In time, the pearl sac's external mantle cells proceed to the formation of tabular aragonite.
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Demecolcine (INN; also known as colcemid) is a drug used in chemotherapy. It is closely related to the natural alkaloid colchicine with the replacement of the acetyl group on the amino moiety with methyl, but it is less toxic. It depolymerises microtubules and limits microtubule formation (inactivates spindle fibre formation), thus arresting cells in metaphase and allowing cell harvest and karyotyping to be performed. During cell division, demecolcine inhibits mitosis at metaphase by inhibiting spindle formation.
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Gary G. Borisy is a retired president and director of the Marine Biological Laboratory in Woods Hole, Massachusetts. In 2013, Borisy joined the Department of Microbiology at the Forsyth Institute. Borisy received his BS in biochemistry (1962) and Ph.D in biophysics (1966) under Edwin Taylor from the University of Chicago, characterizing tubulin and its role in cell division. He then did a postdoc at the Medical Research Council Laboratory of Molecular Biology in Cambridge, England under Hugh Huxley.
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Microalgae are microscopic organisms that can grow via photosynthesis. Many groups grow quickly and are more productive than land plants and macroalgae (seaweed). Microalgae reproduction occurs primarily by vegetative (asexual) cell division, although sexual reproduction can occur in many species under appropriate growth conditions. Microalgae are efficient for fuel production and they are capable of taking a waste (zero-energy) form of carbon () and converting it into a high density liquid form of energy (natural oil).
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Offspring of the females with the trait always inherit the trait (independently from their own gender). Nuclear DNA has two copies per cell (except for sperm and egg cells), one copy being inherited from the father and the other from the mother. Mitochondrial DNA, however, is inherited from the mother only (with some exceptions) and each mitochondrial organelle typically contains between 2 and 10 mtDNA copies. During cell division the mitochondria segregate randomly between the two new cells.
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Acetylation reaction of the K40 lysine in alpha-tubulin, catalyzed by ATAT1. The acetyl group of Acetyl-CoA is transferred to the lysine. Microtubules are highly dynamic tubular polymers assembled from protofilaments of α/β-tubulin dimers, and are essential for intracellular transport, architectural organization, cell division, cellular morphogenesis and force production in eukaryotic cells. There is a constant modulation of the balance between dynamic short-lived, and stable long-lived microtubule subpopulations in the cell.
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The main (67Ga) technique uses scintigraphy to produce two-dimensional images. After the tracer has been injected, images are typically taken by a gamma camera at 24, 48, and in some cases, 72, and 96 hours later. Each set of images takes 30–60 minutes, depending on the size of the area being imaged. The resulting image will have bright areas that collected large amounts of tracer, because inflammation is present or rapid cell division is occurring.
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Chemical treatment on dormant plants has been proven to be an effective method to break dormancy, particularly in woody plants such as grapes, berries, apples, peaches and kiwis. Specifically, hydrogen cyanamide stimulates cell division and growth in dormant plants, causing budbreak when the plant is on the edge of breaking dormancy. Slight injury of cells may play a role in the mechanism of action. The injury is thought to result in increased permeability of cellular membranes.
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