Here, the labyrinthine ridges of a cantaloupe's skin mirror the radial spindles of cellular division observed through a microscope, and cross-sections of vertebrae resemble coiled genetic material.
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With cancer we see uncontrolled cellular division and the spread of cancer cells throughout the body, and in depression we see the workings of neurotransmitters and how molecules affect mood.
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So while researchers were able to successfully create primate embryos on a number of occasions, errors during cellular division meant none of these embryos would last more than a few weeks in a primate's womb.
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There was a magnified picture of cellular division in her biology textbook, and below it the book's previous owner had written GREED in red marker with teardrops coming off the word, like the letters were sweating.
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RNA in situ hybrdization has shown KIAA1147 to be located at high levels in the developing brain. Together, these data suggest that LCHN plays a role in regulating cellular division during development of the brain.
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The nucleoli begin to break down in prophase, resulting in the discontinuation of ribosome production. This indicates a redirection of cellular energy from general cellular metabolism to cellular division. The nuclear envelope stays intact during this process.
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The genus is composed of gammaproteobacterial, secondary- endosymbionts which are gram-negative. Cells are non-flagellated, non-motile, non-spore forming and form long to highly filamentous rods. Cellular division is exhibited through septation. The name 'Arsenophonus nasoniae gen. nov.
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However, nuclei division start happening and many nuclei are produced inside generating giant cells. Surrounding cells will suffer hyperplasia and start cellular division wildly. For M. exigua, these cells will become galls, but not for M. coffeicola.Campos, V. P., Sivapalan, P. & Gnanapragasam, N. C. 1990.
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A tumor is an abnormal growth of body tissue. In the beginning, tumors can be noncancerous, but if they become malignant, they are cancerous. In general, they appear when there is a problem with cellular division. Problems with the body's immune system can lead to tumors.
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Attracted by exudates released by the coffee roots, J2 nematode (migratory stage) moves toward to food source. The nematodes penetrate in the roots and search for a site to feed on. Several cells are selected to start uptaking food. Those cells are modified and grow bigger (hypertrophy) without cellular division.
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Phyllody on a purple coneflower (Echinacea purpurea), a plant development abnormality where leaf-like structures replace flower organs. It can be caused by hormonal imbalance, among other reasons. The word hormone is derived from Greek, meaning set in motion. Plant hormones affect gene expression and transcription levels, cellular division, and growth.
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The cell contained a water-based cytoplasm effectively enclosed by a lipid bilayer membrane. The cell tended to exclude sodium and concentrate potassium by means of specific ion transporters (or ion pumps). The cell multiplied by duplicating all its contents followed by cellular division. The cell used chemiosmosis to produce energy.
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Unlike other multinucleated cells these nuclei contain two distinct lineages of DNA: one from the dinoflagellate and the other from a symbiotic diatom. Some bacteria, such as Mycoplasma pneumoniae, a pathogen of the respiratory tract, may display multinuclear filaments as a result of a delay between genome replication and cellular division.
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MZB exerts its activity through selective inhibition of inosine monophosphate synthetase and guanosine monophosphate synthetase, resulting in the complete inhibition of guanine nucleotide synthesis without incorporation into nucleotides. It arrests DNA synthesis in the S phase of cellular division. Thus, MZB has less toxicity than azathioprine, another immunosuppressant used for some of the same diseases.
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DNA methylation is the modification of DNA nucleotides by addition of a methyl group. These methyl groups are associated with changes in the ability of the corresponding DNA to be used. Patterns of DNA methylation are stable during cellular division. Methylation of tumor suppressor genes in some cancers contributes to the growth and survival of the cancer.
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He spent the following months extending his research, eventually discovering that such oncogene was the mutation of an allele of the Ras subfamily, as well as its activation mechanism. In 2003 he proved that the enzyme CDK2, until then believed to be indispensable in cellular division, was not necessary in order for DNA replication to take place.
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Thiomargarita means "sulfur pearl". This refers to the appearance of the cells; they contain microscopic sulfur granules that scatter incident light, lending the cell a pearly lustre. Like many coccoid bacteria such as Streptococcus, their cellular division tends to occur along a single axis, causing their cells to form chains, rather like strings of pearls. The species name namibiensis means "of Namibia".
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Aurora kinases are serine/threonine kinases that are essential for cell proliferation. They are phosphotransferase enzymes that help the dividing cell dispense its genetic materials to its daughter cells. More specifically, Aurora kinases play a crucial role in cellular division by controlling chromatid segregation. Defects in this segregation can cause genetic instability, a condition which is highly associated with tumorigenesis.
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Sump 1 alone is almost enough to fill an Olympic-size swimming pool. Consistent with landfill practices at that time, no liner was installed at the site. Waste disposal design features such as liners, cellular division of waste, and leachate collection systems were not installed. Instead, the waste materials were placed directly onto the Bay Mud and soils overlying bedrock.
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The human Y chromosome is particularly exposed to high mutation rates due to the environment in which it is housed. The Y chromosome is passed exclusively through sperm, which undergo multiple cell divisions during gametogenesis. Each cellular division provides further opportunity to accumulate base pair mutations. Additionally, sperm are stored in the highly oxidative environment of the testis, which encourages further mutation.
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DnaA protein binding to individual DnaA boxes in the Escherichia coli replication origin, oriC. EMBO J. 1997 November 3; 16(21): 6574–6583. that are recognized by the DnaA protein. DnaA protein plays a crucial role in the initiation of chromosomal DNA replication.Hirota Y, Mordoh J and Jacob F (1970) On the process of cellular division in Escherichia coli III.
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It interacts with the mitotic spindles during cellular division. Due to the usually rapid proliferation of tumour cells, survivin is more expressed during the presence of cancer. The level of survivin correlates to how resistance to chemotherapy a cancerous cell is and how likely that cell is to replicate again. By producing antibodies to target the NES survivin, apoptosis of cancerous cells can be increased.
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Certain mutations and the activation of certain cell-cycle control genes can lead to bacteria forming "filament-like" cells with multiple chromosomes but without cellular division. These mechanisms or mistakes may lead to a similar structure to a coenocyte, though bacteria do not possess nuclei. This fact has been used in certain synthetic biology applications, for example, to create cell-derived fibers for an organically grown concrete.
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A further time- lapse analysis of STE5-8A cells reveals that these mutant cells cannot fully commit to cellular division, as cells exposed to alpha-factor will bud and then revert to mating without completing the cell cycle. Doncic et al. proposed that the incomplete division was due to expression of genes in both the mating pathway and in the G1 cyclin-driven cellular progression.
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Cellular division continues in this manner and the morula stage is reached within the next week. After a total of 21–22 days, the larvae become fully developed and will not hatch until ingested by a host. The larvae can live for a total of six months without the assistance of a host. The timeline of egg development can vary depending on the species.
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Calcium is a necessary ion in the formation of the mitotic spindle. Without the mitotic spindle, cellular division cannot occur. Although young leaves have a higher need for calcium, older leaves contain higher amounts of calcium because calcium is relatively immobile through the plant. It is not transported through the phloem because it can bind with other nutrient ions and precipitate out of liquid solutions.
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Members of the combretastatin family possess varying ability to cause vascular disruption in tumors. Combretastatin binds to the β-subunit of tubulin at what is called the colchicine site, referring to the previously discovered vascular disrupting agent colchicine. Inhibition of tubulin polymerization prevents cancer cells from producing microtubules. Microtubules are essential to cytoskeleton production, intercellular movement, cell movement, and formation of the mitotic spindle used in chromosome segregation and cellular division.
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Once the cell has completed differentiation and become a mature megakaryocyte, it begins the process of producing platelets. The maturation process occurs via endomitotic synchronous replication whereby the cytoplasmic volume enlarges as the number of chromosomes multiplies without cellular division. The cell ceases its growth at 4N, 8N or 16N, becomes granular, and begins to produce platelets. Thrombopoietin plays a role in inducing the megakaryocyte to form small proto-platelet processes.
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"Kinetic Analysis of Regulatory Events in G1 Leading to Proliferation or Quiescence of Swiss 3T3 Cells." PNAS 82 (1985): 5365-369. Like the response to mating pheromones in Hartwell’s experiments, the response to serum starvation was not uniform amongst all cells. Only postmitotic cells younger than three hours arrested cellular division in these conditions, while cells older than four hours were insensitive to the absence of growth factors.
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Through the insertion of multiple genes and telomeres, a shortened minichromosome is produced, which can then be inserted into a host cell A minichromosome is a small chromatin-like structure resembling a chromosome and consisting of centromeres, telomeres and replication origins but little additional genetic material. They replicate autonomously in the cell during cellular division. Minichromosomes may be created by natural processes as chromosomal aberrations or by genetic engineering.
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PDGF plays a role in embryonic development, cell proliferation, cell migration, and angiogenesis. Over- expression of PDGF has been linked to several diseases such as atherosclerosis, fibrotic disorders and malignancies. Synthesis occurs due to external stimuli such as thrombin, low oxygen tension, or other cytokines and growth factors. PDGF is a required element in cellular division for fibroblasts, a type of connective tissue cell that is especially prevalent in wound healing.
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In cell biology, Meiomitosis is an aberrant cellular division pathway that combines normal mitosis pathways with ectopically expressed meiotic machinery resulting in genomic instability. Meiotic pathways are normally restricted to germ cells. Meiotic proteins drive double stranded DNA breaks, chiasma formation, sister chromatid adhesion and rearrange the spindle apparatus. During meiosis, there are 2 sets of cell divisions, the second division is similar to mitosis in that sister chromatids are directly separated.
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Such an observation suggests that the symbiodinium were incorporated into the gametes, the oocytes, during oogenesis– the cellular division process yielding haploid oocytes. There are two primary strategies of symbiodinium uptake by anthozoans. Individuals can either take symbiodinium from the maternal colony, or they can uptake new symbiodinium from the surrounding environment. In situations of environmental uptake, zooplankton can act as an intermediary, transferring the symbiodinium from the surrounding water column, to the daughter colony.
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A very rare type of parasitic twinning is one where a single viable twin is endangered when the other zygote becomes cancerous, or "molar". This means that the molar zygote's cellular division continues unchecked, resulting in a cancerous growth that overtakes the viable fetus. Typically, this results when one twin has either triploidy or complete paternal uniparental disomy, resulting in little or no fetus and a cancerous, overgrown placenta, resembling a bunch of grapes.
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The compound readily eliminates a chloride ion by intramolecular nucleophilic substitution to form a cyclic sulfonium ion. This very reactive intermediate tends to cause permanent alkylation of the guanine nucleotide in DNA strands, which prevents cellular division and generally leads directly to programmed cell death,Mustard agents: description, physical and chemical properties, mechanism of action, symptoms, antidotes and methods of treatment. Organisation for the Prohibition of Chemical Weapons. Accessed June 8, 2010.
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Chaetomium atrobrunneum is strongly cellulolytic, and cellulose- containing growth media can be used to selectively cultivate this and other Chaetomium species. This species has also been reported to produce chaetoatrosin A, a selective inhibitor of chitin synthase II. This enzyme is involved in septum formation and cellular division, and its inhibition by chaetoatrosin A is thought to be the mechanism underlying the antifungal effects of C. atrobrunneum culture filtrates against several medically important fungi including Cryptococcus neoformans.
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Vinca alkaloids are used in chemotherapy for cancer. They are a class of cell cycle–specific cytotoxic drugs that work by inhibiting the ability of cancer cells to divide: Acting upon tubulin, they prevent it from forming into microtubules, a necessary component for cellular division. The vinca alkaloids thus prevent microtubule polymerization, as opposed to the mechanism of action of taxanes. Vinca alkaloids are now produced synthetically and used as drugs in cancer therapy and as immunosuppressive drugs.
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The average cell will divide between 50 and 70 times before cell death. As the cell divides the telomeres on the end of the chromosome get smaller. The Hayflick limit is the theoretical limit to the number of times a cell may divide until the telomere becomes so short that division is inhibited and the cell enters senescence. The phenomenon of limited cellular division was first observed by Leonard Hayflick, and is now referred to as the Hayflick limit.
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When the ER is activated it activates other genes that are responsible for multiple actions of the breast cancer. Activated ER has an effect on cellular division, protease activity, inhibition of cell death and formation of new blood vessels. Aromatase inhibitors affect the ability of estrogens production from androgens by inhibiting the aromatase enzyme activity which is a part of the estrogen pathway . The two categories of AIs are based on their mechanism of action and structure.
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"Regeneration of Vaginal Tissue with non- systemic vaginal administration of Estrogen" May 2009 Lyle, J. Patent application number: 20090124584 There are rudimentary techniques of promoting cellular division to alter the structure of the penis, often referred to as foreskin restoration, and are not to be confused with regeneration. There are manual reconstruction techniques such as those developed by French surgeon Pierre Foldès."Surgical Techniques: Reconstructive Surgery of the Clitoris after Ritual Excision." 2006 Foldes, Pierre J. Sex Medicine 3 pp.
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Most balanced translocation carriers are healthy and do not have any symptoms. It is important to distinguish between chromosomal translocations occurring in gametogenesis, due to errors in meiosis, and translocations that occur in cellular division of somatic cells, due to errors in mitosis. The former results in a chromosomal abnormality featured in all cells of the offspring, as in translocation carriers. Somatic translocations, on the other hand, result in abnormalities featured only in the affected cell line, as in chronic myelogenous leukemia with the Philadelphia chromosome translocation.
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As a result of this stimulation, the B cell can undergo rapid cellular division to form a germinal center where antibody isotype switching and affinity maturation occurs, as well as their differentiation to plasma cells and memory B cells. The end-result is a B cell that is able to mass-produce specific antibodies against an antigenic target. Early evidence for these effects were that in CD40 or CD154 deficient mice, there is little class switching or germinal centre formation, and immune responses are severely inhibited.
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The mitochondrial DNA and other extranuclear types of DNA replicate independently of the DNA located in the nucleus, which is typically arranged in chromosomes that only replicate one time preceding cellular division. The extranuclear genomes of mitochondria and chloroplasts however replicate independently of cell division. They replicate in response to a cell's increasing energy needs which adjust during that cell's lifespan. Since they replicate independently, genomic recombination of these genomes is rarely found in offspring, contrary to nuclear genomes in which recombination is common.
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At the same time, the majority of AT&T; Technologies and the renowned Bell Labs was spun off as Lucent Technologies. The industry as a whole had many other reorganizations since the 1990s, both due to deregulation and because of technological advances reducing demand and pricing power in telecommunications. In 1994, AT&T; purchased the largest cellular carrier, McCaw Cellular, for $11.5 billion and kick-started its cellular division with 2 million subscribers. In 1995, AT&T; purchased long-distance provider Alaska Communications System.
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Some plants like Ficus elastica and Peperomia, which have a periclinal cellular division within the protoderm of the leaves, have an epidermis with multiple cell layers. Epidermal cells are tightly linked to each other and provide mechanical strength and protection to the plant. The walls of the epidermal cells of the above-ground parts of plants contain cutin, and are covered with a cuticle. The cuticle reduces water loss to the atmosphere, it is sometimes covered with wax in smooth sheets, granules, plates, tubes, or filaments.
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At the University of California San Francisco, Blackburn currently researches telomeres and telomerase in many organisms, from yeast to human cells. The lab is focused on telomere maintenance, and how this has an impact on cellular aging. Many chronic diseases have been associated with the improper maintenance of these telomeres, thereby effecting cellular division, cycling, and impaired growth. At the cutting edge of telomere research, the Blackburn lab currently investigates the impact of limited maintenance of telomeres in cells through altering the enzyme telomerase.
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Dryden Mobility was the cellular division of DMTS, with three CDMA cell sites operating in the 800 MHz band, covering the city and approximately 60 kilometers of the Trans Canada Highway. In 2009 Dryden Mobility began conversion to a GSM network in the 850 MHz band intended to cover a greater area than that covered by their CDMA network, from Kenora in the west, to Sioux Lookout to the north, east to Hearst, and south to Sault Ste. Marie.Northern Ontario Business new GSM network. Retrieved 6 October 2009.
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In this sense there are three types of life cycles that utilize sexual reproduction, differentiated by the location of the organism phase(s). In the diplontic life cycle (with pre-gametic meiosis), of which humans are a part, the organism is diploid, grown from a diploid cell called the zygote. The organism's diploid germ-line stem cells undergo meiosis to create haploid gametes (the spermatozoa for males and ova for females), which fertilize to form the zygote. The diploid zygote undergoes repeated cellular division by mitosis to grow into the organism.
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Increased evaporation will lead to an increase in storms in some areas, while leading to accelerated drying of other areas. These storm impacted areas will likely experience increased levels of precipitation and increased flood risks, while areas outside of the storm track will experience less precipitation and increased risk of droughts. Water stress affects plant development and quality in a variety of ways first off drought can cause poor germination and impaired seedling development in plants. At the same time plant growth relies on cellular division, cell enlargement, and differentiation.
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As mentioned above, the G1 cyclins, Cln1/2, are part of a positive feedback loop that promotes their own transcription and the activation of SBF and MBF transcription factors. In 2008, Skotheim et al. proposed that this feedback loop allows for a strong signal to commit to cellular division by the SBF and MBF regulated genes. They hypothesized that without a coherent expression of the genes necessary for early events, like DNA replication and bud-site formation, random individual cellular signals creates noise that weakens the commitment response.
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Circadian rhythms - endogenous, entrainable oscillations in biological processes with periods that roughly correspond to the 24-hour day – were once believed to be an exclusive property of eukaryotic lifeforms. Prokaryotes were thought to lack the cellular complexity to maintain persistent, temperature-compensated timekeeping. In addition, the widely supported "circadian- infradian rule" stipulated that cellular functions could only be coupled to a circadian oscillator in cells dividing only as fast as once in a 24-hour period. Prokaryotes, which often undergo cellular division multiple times in a single day, failed to meet this condition.
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Scientific American Library. . Bacteria often function as multicellular aggregates known as biofilms, exchanging a variety of molecular signals for inter-cell communication, and engaging in coordinated multicellular behaviour. The communal benefits of multicellular cooperation include a cellular division of labour, accessing resources that cannot effectively be used by single cells, collectively defending against antagonists, and optimising population survival by differentiating into distinct cell types. For example, bacteria in biofilms can have more than 500 times increased resistance to antibacterial agents than individual "planktonic" bacteria of the same species.
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Colchicine is widely used in plant breeding by inducing polyploidy in plant cells to produce new or improved varieties, strains and cultivars. Since chromosome segregation is driven by microtubules, colchicine is used in plant cells during cellular division by inhibiting chromosome segregation during meiosis; half the resulting gametes, therefore, contain no chromosomes, while the other half contains double the usual number of chromosomes (i.e., diploid instead of haploid, as gametes usually are), and lead to embryos with double the usual number of chromosomes (i.e., tetraploid instead of diploid).
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Electron microscopy of ultra-thin sections of bacteria I. Cellular division in Bacillus cereus. Journal of Bacteriology 66: 362–373.. His Ph.D. thesis concerned Bacillus cereus, B. megatherium, Escherichia coli, and Protobacterium phosphoreum. In 1953–1954, he was a research assistant at Princeton University; 1954–1956, research associate at Princeton (while being employed by RCA); 1956–1960, Assistant Professor of Zoology at Harvard University; 1960–1963, Associate Professor of Anatomy at Cornell University Medical College; 1963–2011, Professor of Biology at Georgetown University; and 2011–2016, Professor Emeritus at Georgetown.
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These amoeboflagellates also contain a single nucleus, which at this stage in the life cycle is haploid. Under adverse conditions, such as a poor environment, overcrowding or the presence of toxins, these cells can encyst into small, walled cysts that can return to the amoeboflagellate form if conditions improve. The amoeboflagellated stage will undergo sexual reproduction, as two cells fuse to create a diploid cell. This cell will then undergo many rounds of nuclear division without any cellular division, resulting in a rapidly growing, membrane-bound cell with multiple nuclei known as the plasmodium.
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Category:Immunosuppressants Mizoribine (MZB) is an imidazole nucleoside that has been used in renal transplantation, and in steroid-resistant nephrotic syndrome, IgA nephropathy, lupus, as well as for adults with rheumatoid arthritis, lupus nephritis and other rheumatic diseases. MZB exerts its activity through selective inhibition of inosine monophosphate synthetase and guanosine monophosphate synthetase, resulting in the complete inhibition of guanine nucleotide synthesis without incorporation into nucleotides. It arrests DNA synthesis in the S phase of cellular division. Thus, MZB has less toxicity than azathioprine, another immunosuppressant used for some of the same diseases.
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Small nonprotein-coding RNAs (sRNA) are able to perform specific functions without being translated into proteins; 97 bacterial sRNAs from Salmonella Typhi were discovered. AsdA (antisense RNA of dnaA) is a cis- encoded antisense RNA of dnaA described in S. enterica serovar Typhi. It was discovered by deep sequencing and its transcription was confirmed by Northern blot and RACE analysis. AsdA is estimated to be about 540 nucleotides long, and represents the complementary strand to that encoding DnaA, a protein that plays a central role in the initiation of DNA replication and hence cellular division.
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The function of TFH cells. A subset of naive T cells in the T cell zone are activated by antigen and migrate to the follicles where they differentiate into TFH cells that interact with and instruct Follicular B (Fo B) cells to undergo isotype switching, somatic hypermutation, and rapid cellular division to seed germinal centers (GC). Within these germinal centers, TFH cells continue to provide help to GC B cells to facilitate their production of high affinity antibody producing plasma cells (PC) and long-lived memory (Mem) B cells.
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To conclude, spatial localization of cyclin B plays a role in mitotic entry. Translocation of cyclin B from the cytoplasm to the nucleus is necessary for cell division, but not sufficient, as its inhibitors do not allow the cell to enter mitosis prematurely. In addition to the back up inhibition of the cyclin B-Cdk1 complex, premature cellular division is prevented by the translocation of the cyclin B itself. The cyclin B-Cdk1 complex will remain in the cytoplasm in cells with DNA damage, rather than translocate to the nucleus, keeping the cell inhibiting the cell from entering mitosis.
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It is noted by the authors that phosphorylation of cyclin B is nineteen times more favorable in the nucleus than in the cytoplasm, due to the smaller overall volume of the nucleus, allowing a faster phosphorylation rate. The increased translocation due to phosphorylation and increased phosphorylation due to translocation exemplify the positive feedback loop that resembles that previously discovered, which activates the cyclin B-Cdk1 complex. In conclusion, nuclear localization of cyclin B is necessary for cellular entry into mitosis. The translocation of the cyclin from the cytoplasm to the nucleus, which allows for cellular division, is regulated by a positive feedback loop.
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Using a Whi5-GFP fusion protein, they tracked the amount of nuclear Whi5 following the addition of alpha-factor, and noted whether the cell arrested or continued division. As expected pre-Start cells arrested cellular division upon pheromone addition, as indicated by the small fraction of Whi5 export. Conversely, post-Start cells were insensitive to alpha-factor and continued division, as reflected by the large fraction of Whi5 export. Thus, the differential response to the presence of pheromones is reflected in whether the cell is pre- or post-Start, states that can be characterized by how much Whi5 is present in the nucleus.
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The foot portion of the hydra contains the basal disc which allows for the hydra to stick to rocks and other elements. When a hydra gets cut in half, the head portion can regenerate and form a new foot with the basal disc, as well as, the foot portion can regenerate and form a new head with the hypostome region. If a hydra was severed into smaller pieces, the middle pieces would still form a head and foot at the appropriate regions of the hydra. This results in a smaller hydra that was regenerated by morphallaxis and occurs without cellular division.
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Because Motorola relied so long upon the Razr and its derivatives and was slow to develop new products in the growing market for feature-rich touchscreen and 3G phones, the Razr appeal declined while rival offerings like the LG Chocolate, BlackBerry, and iPhone captured, leading Motorola to eventually drop behind Samsung and LG in market share for mobile phones. Motorola's strategy of grabbing market share by selling tens of millions of low-cost Razrs cut into margins and resulted in heavy losses in the cellular division. Motorola capitalized on the Razr too long and it was also slow adopting 3G.
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Germinal centers or germinal centres (GCs) are sites within secondary lymphoid organs – lymph nodes and the spleen – where mature B cells proliferate, differentiate, and mutate their antibody genes (through somatic hypermutation aimed at achieving higher affinity) during a normal immune response to an infection. These develop dynamically after the activation of follicular B cells by T-dependent antigen. As they undergo rapid and mutative cellular division, B cells of the germinal center are known as centroblasts. Once these B cells have stopped proliferating, they are known as centrocytes, and are subjected to selection by follicular helper T (TFH) cells in the presence of follicular dendritic cells (FDCs).
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To further elucidate a biochemical explanation between mating arrest and cell cycle commitment, Doncic et al. conducted the same commitment assay described above on various mutant strains. The mutant, FAR1-S87A, lacks CDK phosphorylation sites, and thus Cln1/2 inhibition of Far1 is compromised. The result is an increase in the amount of Whi5 export required to commit to cellular division, suggesting that Far 1 phosphorylation is key to cellular commitment. Conversely, the mutant, STE5-8A, lacking CDK phosphorylation sites as well (and thus Cln1/2 inhibition of Ste5 is compromised), does not shift the commitment point, suggesting that such inhibition of the mating pathway is not critical for Start.
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The formation of primary plasmodesmata occurs during the part of the cellular division process where the endoplasmic reticulum and the new plate are fused together, this process results in the formation of a cytoplasmic pore (or cytoplasmic sleeve). The desmotubule, also known as the appressed ER, forms alongside the cortical ER. Both the appressed ER and the cortical ER are packed tightly together, thus leaving no room for any luminal space. It is proposed that the appressed ER acts as a membrane transportation route in the plasmodesmata. When filaments of the cortical ER are entangled in the formation of a new cell plate, plasmodesmata formation occurs in land plants.
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Telomerase works by adding base pairs to the overhang of DNA on the 3’ end, extending the strand until DNA polymerase and an RNA primer can complete the complementary strand and successfully synthesize the double stranded DNA. Since DNA polymerase only synthesizes DNA in the leading strand direction, the shortening of the telomere results. Through their research, Blackburn and collaborators were able to show that the telomere is effectively replenished by the enzyme telomerase, which conserves cellular division by preventing the rapid loss of genetic information internal to the telomere, leading to cellular aging. On January 1, 2016, Blackburn was interviewed about her studies, discovering telomerase, and her current research.
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The fluid coating is produced by the body in order to facilitate the transfer of gases between blood and alveolar air, and the type II cells are typically found at the blood-air barrier. Type II cells start to develop at about 26 weeks of gestation, secreting small amounts of surfactant. However, adequate amounts of surfactant are not secreted until about 35 weeks of gestation – this is the main reason for increased rates of infant respiratory distress syndrome, which drastically reduces at ages above 35 weeks gestation. Type II cells are also capable of cellular division, giving rise to more type I and II alveolar cells when the lung tissue is damaged.
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Cleveland has made pioneering discoveries of the mechanisms of chromosome movement and cell-cycle control during normal cellular division, as well as of the principles of neuronal cell development and their relationship to the defects that contribute to inherited neurodegenerative disease. Cleveland's research looks at the molecular genetics of axonal growth and motor neuron disease and the cell biology of mammalian chromosome movement. Most recently, his research has achieved a significant breakthrough in treating Huntington's disease, an inherited and degenerative brain disorder for which there is no cure. A one-time injection of a new DNA-based drug treatment - known as ASO (short for antisense oligonucleotide) - blocked the activity of the gene whose mutation causes the disease.
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Retrieved on 2013-07-10. Because Motorola relied so long upon the Razr and its derivatives and was slow to develop new products in the growing market for feature-rich touchscreen and 3G phones, the Razr appeal declined, leading Motorola to eventually drop behind Samsung and LG in market share for mobile phones. Motorola's strategy of grabbing market share by selling tens of millions of low-cost Razrs cut into margins and resulted in heavy losses in the cellular division. In October 2011, Motorola resurrected the Razr brand for a line of Android smartphones: the Droid Razr for Verizon Wireless (known simply as the "Motorola RAZR" on other networks) and an improved variant, the Droid Razr Maxx.
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Several processes are known to have developed for organelle biogenesis. These can range from de novo synthesis to the copying of a template organelle; the formation of an organelle 'from scratch' and using a preexisting organelle as a template to manufacture an organelle, respectively. The distinct structures of each organelle are thought to be caused by the different mechanisms of the processes which create them and the proteins that they are made up of. Organelles may also be 'split' between two cells during the process of cellular division (known as organelle inheritance), where the organelle of the parent cell doubles in size and then splits with each half being delivered to their respective daughter cells.
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The components of an effective rehabilitation program for all sprain injuries include increasing the range of motion of the affected joint and progressive muscle strengthening exercises. After implementing conservative measures to reduce swelling and pain, mobilizing the limb within 48–72 hours following injury has been shown to promote healing by stimulating growth factors in musculoskeletal tissues linked to cellular division and matrix remodeling. Prolonged immobilization can delay the healing of a sprain, as it usually leads to muscle atrophy and weakness. Although prolonged immobilization can have a negative effect on recovery, a study in 1996 suggest that the use of bracing can improve healing by alleviating pain and stabilizing the injury to prevent further damage to the ligament or re-injury.
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Moreover, it is involved in many cell signaling pathways and in the uptake of extracellular material (endocytosis), the segregation of chromosomes during cellular division, the cytokinesis stage of cell division, as scaffolding to organize the contents of the cell in space and in intracellular transport (for example, the movement of vesicles and organelles within the cell) and can be a template for the construction of a cell wall. Furthermore, it can form specialized structures, such as flagella, cilia, lamellipodia and podosomes. The structure, function and dynamic behavior of the cytoskeleton can be very different, depending on organism and cell type. Even within one cell, the cytoskeleton can change through association with other proteins and the previous history of the network.
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The queen is saved by the quick reactions of her attendant John Brown, and she and the surviving officers barricade themselves in the mess hall as the Vrall feast outside. By the time the TARDIS arrives, the Vrall have begun to reproduce by cellular division, and it is clear that there is no hope of containing them. The Doctor therefore returns to the citadel on the Moon to collect the weapons which the hunters would have used against the Vrall, and he finds what he needs and escapes moments before the citadel finally self-destructs, leaving only an unusually deep crater. The Doctor, Turlough and Kamelion then return to Earth, and use their weapons to kill the Vrall before they can break into the mess hall.
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In 1878, he obtained a post of professor at the University of Geneva where in the following year, he observed the penetration of a spermatozoon into an egg becoming thus a pioneer of the microscopic studies of fertilisation and cellular division. In 1886, he resigned from his post in Geneva to devote himself entirely to his research in Villefranche-sur- Mer where, in 1880, he had established a small marine laboratory with Jules Henri Barrois (1852–1943). Then, financially aided by the French government to carry out a study of distribution of sponges on the Tunisian and Greek coasts, he departed Le Havre on his new yacht, l' Aster on March 13, 1892, accompanied by several team members. After a stopover in Bénodet, the yacht disappeared at sea, and Fol was never seen again.
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For their research and contributions to the understanding of telomeres and the enzyme telomerase, Elizabeth Blackburn, Carol Greider, and Jack Szostaks were awarded the 2009 Nobel Prize in Physiology or Medicine. The substantial research on the effects of chromosomal protection from telomerase, and the impact this has on cellular division has been a revolutionary catalyst in the field of molecular biology. For example, the addition of telomerase to cells that do not possess this enzyme has shown to bypass the limit of cellular aging in those cells, thereby linking this enzyme to reduced cellular aging. The addition of telomerase, and the presence of the enzyme in cancer cells has been shown to provide an immunity mechanism for the cell in proliferating, linking the transferase activity to increased cellular growth and reduced sensitivity for cellular signalling.
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In 1994 the merger of the two companies was completed when AT&T; purchased the rest of McCaw Cellular for $11.5 billion, at that time the second largest merger in US history, second only to the RJR Nabisco takeover documented in Barbarians at the Gate. The merger was completed in late 1994, creating AT&T; Wireless Group, which was at that time the largest cellular carrier in the US. AT&T; kick-started their cellular division with 2 million subscribers. As a result of the merger, Craig McCaw became one of AT&T;'s largest shareholders, but he refused to sit on the Board of Directors because he couldn't stand long meetings. McCaw left daily operations to focus on Teledesic, passing control of AT&T; Wireless to James Barksdale, and then Steve Hooper when Barksdale left for Netscape.
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The finds offer direct evidence that confirms expectations that major evolutionary diversification of animals already had occurred before the onset of the Cambrian period, with its apparent 'explosion' of metazoan life-forms and, therefore, that more remote ancestral forms of the phyla recognizable in Cambrian macrofossils must have existed previously. The documented biota now includes phosphatized microfossils of algae, multicellular thallophytes (seaweeds), acritarchs, ciliates, and cyanophytes, besides adult sponges and adult cnidarians (coelenterates; these may be early forms of tabulate corals (tetracorallians)). There also seem to be what scientists cautiously report as bilateral animal embryos, termed Parapandorina, and eggs (Megasphaera). Some of the possible animal embryos are in an early stage of cellular division (that was first interpreted as spores or algal cells), including eggs and embryos which are most probably of sponges or cnidarians, as well as adult sponges and a variety of adult cnidarians.
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The authors say that their results rule out the existence of nanobacteria as living entities and that they are instead a unique self-propagating entity, namely self-propagating mineral-fetuin complexes. An April 2008 Proceedings of the National Academy of Sciences (PNAS) article also reported that blood nanobacteria are not living organisms and stated that "CaCO3 precipitates prepared in vitro are remarkably similar to purported nanobacteria in terms of their uniformly sized, membrane- delineated vesicular shapes, with cellular division-like formations and aggregations in the form of colonies." The growth of such "biomorphic" inorganic precipitates was studied in detail in a 2009 Science paper, which showed that unusual crystal growth mechanisms can produce witherite precipitates from barium chloride and silica solutions that closely resemble primitive organisms. The authors commented on the close resemblance of these crystals to putative nanobacteria, stating that their results showed that evidence for life cannot rest on morphology alone.
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Another, and perhaps more helpful way to visualize this effect is to look at photomicroscopy slides. Initially, slides of RAD+ and rad9 haploid cells in the exponential phase of growth show simple, single cells, that are indistinguishable from each other. However, the slides look much different after being exposed to x-irradiation for 10 hours. The RAD+ slides now show RAD+ cells existing primarily as two-budded microcolonies, suggesting that cell division has been arrested. In contrast, the rad9 slides show the rad9 cells existing primarily as 3 to 8 budded colonies, and they appear smaller than the RAD+ cells. This is further evidence that the mutant RAD cells continued to divide and are deficient in G2 arrest. However, there is evidence that although the RAD9 gene is necessary to induce G2 arrest in response to DNA damage, giving the cell time to repair the damage, it does not actually play a direct role in repairing DNA. When rad9 cells are artificially arrested in G2 with MBC, a microtubule poison that prevents cellular division, and then treated with x-irradiation, the cells are able to repair their DNA and eventually progress through the cell cycle, dividing into viable cells.
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