"Sexual and emotional responses are fundamental drivers of human behavior, and the links among sex, bonding, and reproduction ultimately ensure the survival of most mammalian species," write researchers from Imperial College London.
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While it's a fact that most mammalian societies are male-dominant, the point is that nature doesn't have to follow that rule, as evidenced by the wide spectrum of behaviors that exist.
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Half of the membrane mass in human and most mammalian red blood cells are proteins. The other half are lipids, namely phospholipids and cholesterol.
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This is two phenylalanines in an acidic tract. It is bound by the endoplasmic reticulum to a lot of proteins involved in lipid metabolism. It is contained in most mammalian ORPs and in about 40% of yeast's ORPs.
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The eIF3 complex is broadly conserved across eukaryotes, but the conservation of individual subunits varies across organisms. For instance, while most mammalian eIF3 complexes are composed of 13 subunits, budding yeast's eIF3 has only six subunits (eIF3a, b, c, g, i, j).
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Some parts of the iris are poisonous. Because both the foliage and rhizomes are deadly toxic, most mammalian herbivores usually leave Iris untouched, although the Muskrat (Ondatra zibethicus) occasionally feeds on their rhizomes and lower stems and the White-Tailed Deer (Odocoileus virginianus) sometimes nibbles the leaf edges.
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The extinction of multituberculates has been a topic of controversy for several decades. After at least 88 million years of dominance over most mammalian assemblies, multituberculates reached the peak of their diversity in the early Palaeocene, before gradually declining across the final stages of the epoch and the Eocene, finally disappearing in the early Oligocene (mid-Miocene if gondwanatherians are multituberculates). Traditionally, the extinction of multituberculates has been linked to the rise of rodents (and, to a lesser degree, earlier placental competitors like hyopsodonts and Plesiadapiformes), which supposedly competitively excluded multituberculates from most mammalian faunas. However, the idea that multituberculates were replaced by rodents and other placentals has been criticised by several authors.
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NONO is found in the nucleus of most mammalian cells and is primarily distributed within the nucleoplasm, it can also be found concentrated within sub-nuclear domains known as paraspeckles. NONO has also been observed within the brain, localised in the cytoplasm of hippocampal neurons that are associated with RNA transport granules.
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Nearly all mammals display sex-dimorphic reproductive and sexual behavior (e.g., lordosis and mounting in rodents). Much research has made it clear that prenatal and early postnatal androgens play a role in the differentiation of most mammalian brains. Experimental manipulation of androgen levels in utero or shortly after birth can alter adult reproductive behavior.
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C7ORF30 is located on chromosome 7 in humans and runs from 23,305,465 to 23,315,705. There are four predicted exons in the human gene with conservation occurring across most mammalian species. There is no conclusive data regarding whether the gene is ubiquitously expressed in human tissues, but expressed sequence tag databases show that it is expressed in many tissues.
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Sexual motivation is influenced by hormones such as testosterone, estrogen, progesterone, oxytocin, and vasopressin. In most mammalian species, sex hormones control the ability to engage in sexual behaviors. However, sex hormones do not directly regulate the ability to copulate in primates (including humans). Rather, sex hormones in primates are only one influence on the motivation to engage in sexual behaviours.
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As the growth cone slows down, branches begin to form through one of two modalities: splitting of the growth cone, or interstitial branching. Growth cone splitting results in bifurcation of the main axon and is associated with axon guidance and innervating multiple faraway targets. Conversely, interstitial branching increases axonal coverage locally to define its presynaptic territory. Most mammalian CNS branches extend interstitially.
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Glucose Glucose transporters are a wide group of membrane proteins that facilitate the transport of glucose across the plasma membrane, a process known as facilitated diffusion. Because glucose is a vital source of energy for all life, these transporters are present in all phyla. The GLUT or SLC2A family are a protein family that is found in most mammalian cells. 14 GLUTS are encoded by human genome.
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As a result, when serum concentration is increased in a gradual manner, most mammalian cells respond in a switch-like manner in entering S-phase. This mitogen stimulated, bistable E2F switch is exhibits hysteresis, as cells are inhibited from returning to G1 even after mitogen withdrawal post E2F activation.Yao, Guang, et al. “A Bistable Rb-E2F Switch Underlies the Restriction Point.” Nature Cell Biology, vol.
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C2orf81 has a molecular weight of 66.6 kDa and its isoelectric point is 5.32. It contains a high amount of prolines in the human protein and most mammalian homologs, but a higher amount of glutamic acid residues in non- mammalian vertebrate homologs. C2orf81 has 4 isoforms and its most common isoform contains 615 amino acids. Isoforms 2 through 4 have 566, 520 and 588 amino acids respectively.
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Microtubule plus ends are often localized to particular structures. In polarized interphase cells, microtubules are disproportionately oriented from the MTOC toward the site of polarity, such as the leading edge of migrating fibroblasts. This configuration is thought to help deliver microtubule-bound vesicles from the Golgi to the site of polarity. Dynamic instability of microtubules is also required for the migration of most mammalian cells that crawl.
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These pumps allow the inside of the embryo to fill with blastocoelic fluid, which supports the further growth of life. The blastomere is considered totipotent. That is, blastomeres are capable of developing from a single cell into a fully fertile adult organism. This has been demonstrated through studies and conjectures made with mouse blastomeres, which have been accepted as true for most mammalian blastomeres as well.
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Nest location can provide partial protection from most mammalian nest predators, especially if placed on islands or floating vegetation in deep waters. Most of the same predators will prey on young cygnets, as will common snapping turtle (Chelhydra serpentina), California gull (Larus californicus), great horned owl (Bubo virginianus), red fox (Vulpes vulpes) and American mink (Mustela vison).Abel, R. A. (1993). Trumpeter swan reintroduction.
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Potassium inwardly-rectifying channel, subfamily J, member 8, also known as KCNJ8, is a human gene encoding the Kir6.1 protein. A mutation in KCNJ8 has been associated with cardiac arrest in the early repolarization syndrome. Potassium channels are present in most mammalian cells, where they participate in a wide range of physiologic responses. Kir6.1 is an integral membrane protein and inward-rectifier type potassium channel.
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The preproinsulin precursor of insulin is encoded by the INS gene, which is located on Chromosome 11p15.5.. In some mammals, such as rats and mice, there are two insulin genes, one of which is the homolog of most mammalian genes (Ins2), and the other of which is a retroposed copy that includes promoter sequence but that is missing an intron (Ins1). Both rodent insulin genes are functional.
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The palmaris is a popular source of tendon material for grafts and this has prompted studies which have shown the absence of the palmaris does not have any appreciable effect on grip strength. The levator claviculae muscle in the posterior triangle of the neck is a supernumerary muscle present in only 2–3% of all people but nearly always present in most mammalian species, including gibbons and orangutans.
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Galactose-alpha-1,3-galactose, commonly known as alpha gal and the Galili antigen, is a carbohydrate found in most mammalian cell membranes. It is not found in primates, including humans, who have lost the GGTA1 gene. Their immune systems recognize it as a foreign body and produce xenoreactive immunoglobulin M antibodies, leading to organ rejection after transplantation. Anti-alpha gal immunoglobulin G antibodies are some of the most common in humans.
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In most mammalian species, the mother bites through the cord and consumes the placenta, primarily for the benefit of prostaglandin on the uterus after birth. This is known as placentophagy. However, it has been observed in zoology that chimpanzees apply themselves to nurturing their offspring, and keep the fetus, cord, and placenta intact until the cord dries and detaches the next day. The placenta exists in most mammals and some reptiles.
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Orthologs have been determined in most eukaryotes, the most highly conserved being found in most mammalian species. Moderate conservation is maintained among other distant species such as: Gallus gallus, Xenopus, Strongylocentrotus purpuratus, Tetraodon, etc. The PRCC1 gene has two distinct regions: a proline-rich region on the N-terminus, and the DUF84 region on the C-terminus. The DUF84 region is found in the genome of a bacterium called Vibrio cholerae.
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Potassium channels are present in most mammalian cells, where they participate in a wide range of physiologic responses. Kir4.2 is an integral membrane protein and inward-rectifier type potassium channel. Kir4.2 has a greater tendency to allow potassium to flow into a cell rather than out of a cell. Three transcript variants encoding the same protein have been found for this gene. The existing literature describing KCNJ15 and Kir4.2 is sparse.
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The estrous cycle or oestrous cycle (derived from Latin oestrus "frenzy", originally from Greek οἶστρος oîstros "gadfly") is the set of recurring physiological changes that are induced by reproductive hormones in most mammalian therian females. Estrous cycles start after sexual maturity in females and are interrupted by anestrous phases or by pregnancies. Typically, estrous cycles continue until death. Some animals may display bloody vaginal discharge, often mistaken for menstruation.
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These are found in snake tongues, many lizard tongues, and the mammalian anteaters. The muscles perpendicular to the long axis may be arranged in a transverse, circular, or radial pattern. A transverse arrangement involves sheets of muscle fibers running perpendicular to the long axis, usually alternating between horizontal and vertical orientations. This arrangement is found in the arms and tentacles of squid, octopuses, and in most mammalian tongues.
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Many animals have as many or more CYP genes than humans do. Reported numbers range from 35 genes in the sponge Amphimedon queenslandica to 235 genes in the cephalochordate Branchiostoma floridae. Mice have genes for 101 CYPs, and sea urchins have even more (perhaps as many as 120 genes). Most CYP enzymes are presumed to have monooxygenase activity, as is the case for most mammalian CYPs that have been investigated (except for, e.g.
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This inhibition provides negative feedback control on the HPG axis. KNDy peptide colocalization was first discovered in 2007 in sheep and was later confirmed to be present in mice, rats, cows and nonhuman primates. KNDy neurons are thought to be located in the hypothalamus region of human brains due to conservation across most mammalian species. Other roles of KNDy neurons include influences on prolactin production; puberty; stress' effects on reproduction; and the control of thermoregulation.
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The complexity in bacterial responses appears to be in the number of proteins induced by oxidative stress. In mammalian cells, the number of proteins induced is small but the regulatory pathways are highly complex. The inducers of oxidative stress responses in bacteria appear to be either the oxidant itself or interaction of the oxidant with a cell component. Most mammalian cells exist in an environment where the oxygen concentration is constant, thus responses are not directly stimulated by oxidants.
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Potassium inwardly-rectifying channel, subfamily J, member 16 (KCNJ16) is a human gene encoding the Kir5.1 protein. Potassium channels are present in most mammalian cells, where they participate in a wide range of physiologic responses. Kir5.1 is an integral membrane protein and inward-rectifier type potassium channel. Kir5.1, which has a greater tendency to allow potassium to flow into a cell rather than out of a cell, can form heterodimers with two other inward-rectifier type potassium channels.
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Potassium channels are present in most mammalian cells, where they participate in a wide range of physiologic responses. The protein encoded by this gene is an integral membrane protein and inward-rectifier type potassium channel. The encoded protein, which has a greater tendency to allow potassium to flow into a cell rather than out of a cell, is controlled by G-proteins. It associates with another G-protein-activated potassium channel to form a heteromultimeric pore- forming complex.
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Potassium inwardly-rectifying channel, subfamily J, member 14 (KCNJ14), also known as Kir2.4, is a human gene. Potassium channels are present in most mammalian cells, where they participate in a wide range of physiologic responses. The protein encoded by this gene is an integral membrane protein and inward-rectifier type potassium channel, and probably has a role in controlling the excitability of motor neurons. Two transcript variants encoding the same protein have been found for this gene.
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Puberty coincides with the beginning of estrous cycles. Estrous cycles are the recurring hormonal and physiological changes that occur within the bodies of most mammalian females that lead to ovulation and the development of a suitable environment for embryonic and fetal growth. The cow is considered [poly-estrous], which means that she will continue to undergo regular estrous cycles until death unless the cycle is interrupted by a pregnancy. In cows, a complete estrous cycle lasts 21 days.
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Interspersed repetitive DNA is found in all eukaryotic genomes. They differ from tandem repeat DNA in that rather than the repeat sequences coming right after one another, they are dispersed throughout the genome and nonadjacent. The sequence that repeats can vary depending on the type of organism, and many other factors. Certain classes of interspersed repeat sequences propagate themselves by RNA mediated transposition; they have been called retrotransposons, and they constitute 25–40% of most mammalian genomes.
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Birds typically have two paired ceca, as, unlike other mammals, do hyraxes. Parrots do not have ceca. Most mammalian herbivores have a relatively large cecum, hosting a large number of bacteria, which aid in the enzymatic breakdown of plant materials such as cellulose; in many species, it is considerably wider than the colon. In contrast, obligatory carnivores, whose diets contain little or no plant material, have a reduced cecum, which is often partially or wholly replaced by the appendix.
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Potassium channels are present in most mammalian cells, where they participate in a wide range of physiologic responses. The protein encoded by this gene is an integral membrane protein and inward-rectifier type potassium channel. It is inhibited by internal ATP and probably plays an important role in potassium homeostasis. The encoded protein has a greater tendency to allow potassium to flow into a cell rather than out of a cell (hence the term "inwardly rectifying").
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In humans, this is called the ovulatory cycle, or menstrual cycle. The period of high fertility is also called the fertile window, and is the only time during the cycle when sex can result in conception. Females of most mammalian species display hormonally-induced physical and behavioral signals of their fertility during the fertile window, such as sexual swellings and increased motivation to mate. Some species will not—or cannot—engage in sex at all outside of this window.
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Potassium channels are present in most mammalian cells, where they participate in a wide range of physiologic responses. The protein encoded by this gene is an integral membrane protein and inward- rectifier type potassium channel. The encoded protein, which has a greater tendency to allow potassium to flow into a cell rather than out of a cell, is controlled by G-proteins. It may associate with other G-protein-activated potassium channel subunits to form a heterotetrameric pore-forming complex.
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It agglutinates most mammalian red blood cell types. As a toxin, it can cause poisoning in monogastric animals, such as humans, through the consumption of raw or improperly prepared kidney beans. Measured in haemagglutinating units (hau), a raw red kidney bean may contain up to 70,000 hau. This can be reduced to safe levels by correct cooking by boiling unsoaked beans for at least 30 minutes, presoaked beans for 15 minutes, 2 hours at , or 45 minutes pressure cooked at 15 psi.
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Most mammalian species produce sound by passing air from the lungs across the larynx, vibrating the vocal folds. Sound then enters the supralaryngeal vocal tract, which can be adjusted to produce various changes in sound output, providing refinement of vocalizations. Although morphological differences between species affect sound production, neural control is thought to be more essential factor in producing the variations within human speech and song compared to those of other mammals. Toothed whale (Odontocete) vocal anatomy Cetacean vocalizations are an exception to this general mechanism.
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This medium contains a great deal of phosphate and is formulated for use in a 5% carbon dioxide atmosphere. RPMI 1640 has traditionally been used for the serum-free expansion of human lymphoid cells. RPMI 1640 uses a bicarbonate buffering system and differs from most mammalian cell culture media in its typical pH 8 formulation. Properly supplemented with serum or an adequate serum replacement, RPMI 1640 allows the cultivation of many cell types, especially human T/B-lymphocytes, bone marrow cells, and hybridoma cells.
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Mammary glands are most obvious in humans, as the female human body stores large amounts of fatty tissue near the nipples, resulting in prominent breasts. Mammary glands are present in all mammals, although they are seldom used by the males of the species. Most mammalian females have two copies of the X chromosome as opposed to males which have only one X and one smaller Y chromosome; some mammals, such as the platypus, have different combinations.Adrian T. Sumner, Chromosomes: Organization and Function (2008), pp.
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N-acetyltransferase (NAT) is an enzyme that catalyzes the transfer of acetyl groups from acetyl-CoA to arylamines, arylhydroxylamines and arylhydrazines. They have wide specificity for aromatic amines, particularly serotonin, and can also catalyze acetyl transfer between arylamines without CoA. N-acetyltransferases are cytosolic enzymes found in the liver and many tissues of most mammalian species, except the dog and fox, which cannot acetylate xenobiotics. Acetyl groups are important in the conjugation of metabolites from the liver, to allow excretion of the byproducts (phase II metabolism).
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Non-motile cilia are also called primary cilia which serve as sensory organelles. Most mammalian cell types possess a single non-motile, primary cilium, which functions as a cellular antenna. Exceptions include olfactory neurons which possess several non-motile cilia and cells of the transient embryonic node, which possess singular motile cilia known as nodal cilia, critical for the establishment of left to right body asymmetry. In eukaryotes, motile cilia and flagella (together known as undulipodia) are structurally similar, although distinctions are sometimes made according to function or length.
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While lipid tails primarily modulate bilayer phase behavior, it is the headgroup that determines the bilayer surface chemistry. Most natural bilayers are composed primarily of phospholipids, but sphingolipids and sterols such as cholesterol are also important components. Of the phospholipids, the most common headgroup is phosphatidylcholine (PC), accounting for about half the phospholipids in most mammalian cells. PC is a zwitterionic headgroup, as it has a negative charge on the phosphate group and a positive charge on the amine but, because these local charges balance, no net charge.
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If binding occurs, a series of events is initiated culminating in cell death via apoptosis. In this manner, the human body eliminates any cells infected by a virus or expressing proteins they shouldn't be (e.g. cancerous cells). For humans, as in most mammalian populations, MHC Class I molecules are extremely variable in their primary structure, and HLA-A is ranked among the genes in humans with the fastest- evolving coding sequence. As of December 2013, there are 2432 known HLA-A alleles coding for 1740 active proteins and 117 null proteins.
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Potassium channels are present in most mammalian cells, where they participate in a wide range of physiologic responses. The protein encoded by this gene is an integral membrane protein and inward-rectifier type potassium channel. The encoded protein, which has a greater tendency to allow potassium to flow into a cell rather than out of a cell, is controlled by G-proteins and may be involved in the regulation of insulin secretion by glucose. It associates with two other G-protein-activated potassium channels to form a heteromultimeric pore-forming complex.
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Potassium inwardly-rectifying channel, subfamily J, member 3, also known as KCNJ3 or Kir3.1, is a human gene. Potassium channels are present in most mammalian cells, where they participate in a wide range of physiologic responses. The protein encoded by this gene is an integral membrane protein and inward-rectifier type potassium channel. The encoded protein, which has a greater tendency to allow potassium to flow into a cell rather than out of a cell, is controlled by G-proteins and plays an important role in regulating heartbeat.
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A third, evolutionarily younger, function of the basilar membrane is strongly developed in the cochlea of most mammalian species and weakly developed in some bird species: Fritzsch B: The water-to-land transition: Evolution of the tetrapod basilar papilla; middle ear, and auditory nuclei. In: the dispersion of incoming sound waves to separate frequencies spatially. In brief, the membrane is tapered and it is stiffer at one end than at the other. Furthermore, sound waves travelling to the "floppier" end of the basilar membrane have to travel through a longer fluid column than sound waves travelling to the nearer, stiffer end.
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After cleavage by the protease, prelamin A is referred to as lamin A. In most mammalian cells, lamin A, along with lamin B1, lamin B2 and lamin C, makes up the nuclear lamina, which provides structural support to the nucleus. Before the late 20th century, research on progeria yielded very little information about the syndrome. In 2003, the cause of progeria was discovered to be a point mutation in position 1824 of the LMNA gene, which replaces a cytosine with thymine. This mutation creates a 5' cryptic splice site within exon 11, resulting in a shorter than normal mRNA transcript.
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The MC1R protein lies within the cell membrane, and is signalled by melanocyte-stimulating hormone (MSH) released by the pituitary gland. When activated by one of the variants of MSH, typically α-MSH, MC1R initiates a complex signaling cascade that leads to the production of the brown or black pigment eumelanin. In contrast, the receptor can also be antagonized by agouti signalling peptide (ASIP), which reverts the cell back to producing the yellow or red phaeomelanin. The pulsatile nature of ASIP signalling through MC1R produces the characteristic yellow and black agouti banding pattern observed on most mammalian hair.
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Glucose and glutamine are the major carbon sources of most mammalian cells, and glucose metabolism is closely related to histone acetylation and deacetylation. Glucose availability affects the intracellular pool of acetyl-CoA, a central metabolic intermediate that is also the acetyl donor in histone acetylation. Glucose is converted to acetyl-CoA by the pyruvate dehydrogenase complex (PDC), which produces acetyl-CoA from glucose- derived pyruvate; and by adenosine triphosphate-citrate lyase (ACLY), which generates acetyl-CoA from glucose-derived citrate. PDC and ACLY activity depend on glucose availability, which thereby influences histone acetylation and consequently modulates gene expression and cell cycle progression.
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The main concern is neurotoxicity, which in most mammalian species may manifest as central nervous system depression, and consequent ataxia, as might be expected from potentiation of inhibitory GABA-ergic synapses. Since drugs that inhibit the enzyme CYP3A4 often also inhibit P-glycoprotein transport, the risk of increased absorption past the blood- brain barrier exists when ivermectin is administered along with other CYP3A4 inhibitors. These drugs include statins, HIV protease inhibitors, many calcium channel blockers, lidocaine, the benzodiazepines, and glucocorticoids such as dexamethasone.Goodman and Gilman's The Pharmacological Basis of Therapeutics, 11th edition, pages 122, 1084–1087.
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Exosomes were first discovered in the maturing mammalian reticulocyte (immature red blood cell) by Stahl and group in 1983 and Johnstone and group in 1983 further termed 'exosomes' by Johnstone and group in 1987. Exosomes were shown to participate in selective removal of many plasma membrane proteins as the reticulocyte becomes a mature red blood cell (erythrocyte). In the reticulocyte, as in most mammalian cells, portions of the plasma membrane are regularly internalized as endosomes, with 50 to 180% of the plasma membrane being recycled every hour. In turn, parts of the membranes of some endosomes are subsequently internalized as smaller vesicles.
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On average, male mammals are larger than females, with males being at least 10% larger than females in over 45% of investigated species. Most mammalian orders are also exhibit male-biased sexual dimorphism, although some orders do not show any bias or are significantly female-biased (Lagomorpha). Sexual size dimorphism increases with body size across mammals (Rensch’s rule), suggesting that there are parallel selection pressures on both male and female size. Male-biased dimorphism relates to sexual selection on males through male–male competition for females, as there is a positive correlation between the degree of sexual selection, as indicated by mating systems, and the degree of male-biased size dimorphism.
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There are hotspots in the genome where DNA sequences are prone to gaps and breaks after inhibition of DNA synthesis such as in the aforementioned checkpoint arrest. These sites are called fragile sites, and can occur commonly as naturally present in most mammalian genomes or occur rarely as a result of mutations, such as DNA-repeat expansion. Rare fragile sites can lead to genetic disease such as fragile X mental retardation syndrome, myotonic dystrophy, Friedrich’s ataxia, and Huntington’s disease, most of which are caused by expansion of repeats at the DNA, RNA, or protein level. Although, seemingly harmful, these common fragile sites are conserved all the way to yeast and bacteria.
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In most mammalian species the result is a system of rank or sexual competition that results in either polygyny, or lifelong pair-bonding between two individuals who live relatively independent of other adults of their species; in both cases male aggression plays an important role in maintaining sexual access to mate(s). What is uniquely characteristic about human societies is what required symbolic cognition, which consequently leads to the evolution of culture: "cooperative, mixed-sex social groups, with significant male care and provisioning of offspring, and relatively stable patterns of reproductive exclusion." This combination is relatively rare in other species because it is "highly susceptible to disintegration." Language and culture provide the glue that holds it together.
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Anatoliadelphys maasae is an extinct genus of predatory metatherian mammal from the Eocene of Europe. It was an arboreal, cat-sized animal, with powerful crushing jaws similar to those of the modern Tasmanian devil. Although most mammalian predators of the northern hemisphere in this time period were placentals, Europe was an archipelago, and the island landmass now forming Turkey might have been devoid of competing mammalian predators, though this may not matter since other carnivorous metatherians are also known from the Cenozoic in the Northern Hemisphere. Nonetheless, it stands as a reminder that mammalian faunas in the Paleogene of the Northern Hemisphere were more complex than previously thought, and metatherians did not lose their hold as major predators after their success in the Cretaceous.
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After cloning two distinct genes for 5-HT1B and 5-HT1D receptors, a better insight into distribution and expression in different tissues was gained, except in brain tissue where they are overlapping in several areas. Most mammalian species, including humans, have 5-HT1D binding sites widely distributed throughout the central nervous system. 5-HT1D receptors are found in all areas of the brain but they differ in quantity at each area. An important initiator of head pain is suggested to be the activation of trigeminovascular afferent nerves which upon activation releases neuropeptides such as CGRP, substance P and neurokinin A. Also they are thought to promote neurogenic inflammatory response important for sensitization of sensory afferents, and also transmission and generation of head pain centrally.
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The term Feed ban is usually a reference to the Food and Drug Administration (FDA) regulations that since 1997 have prohibited the feeding of most mammalian-derived proteins to cattle as a method of preventing the spread of bovine spongiform encephalopathy (BSE). Feeding of infected ruminant material back to ruminants is believed to be the most likely means of transmission of the disease. Exceptions to the FDA ban have existed for mammalian blood and blood products; gelatin; inspected cooked meat products for humans; milk products; and products containing pork and equine (and avian) proteins. On January 26, 2004, FDA officials said they would expand the feed ban by prohibiting, from ruminant feeds, ruminant blood and blood products, poultry litter, and restaurant plate waste.
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The LOCS (originating from both the intrinsic and shell neurons) contains unmyelinated fibres that synapse with the dendrites of the Type I spiral ganglion cells projecting to the inner hair cells. While the intrinsic LOCS neurons tend to be small (~10 to 15 µm in diameter), and the shell OC neurons are larger (~25 µm in diameter), it is the intrinsic OC neurons that possess the larger axons (0.77 µm compared to 0.37 µm diameter for shell neurons). In contrast, the MOCS contains myelinated nerve fibres which innervate the outer hair cells directly. Although both the LOCS and MOCS contain crossed (contralateral) and uncrossed (ipsilateral) fibres, in most mammalian species the majority of LOCS fibres project to the ipsilateral cochlea, whilst the majority of the MOCS fibres project to the contralateral cochlea.
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Members of the TLR family were detected on glia, neurons and on neural progenitor cells in which they regulate cell-fate decision. It has been estimated that most mammalian species have between ten and fifteen types of toll-like receptors. Thirteen TLRs (named simply TLR1 to TLR13) have been identified in humans and mice together, and equivalent forms of many of these have been found in other mammalian species. However, equivalents of certain TLR found in humans are not present in all mammals. For example, a gene coding for a protein analogous to TLR10 in humans is present in mice, but appears to have been damaged at some point in the past by a retrovirus. On the other hand, mice express TLRs 11, 12, and 13, none of which is represented in humans.
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Most mammalian cells can replicate a limited number of times due to progressive shortening of telomeres; virtually all malignant cancer cells gain an ability to maintain their telomeres, conferring "limitless replicative potential". As cells cannot survive at distances of more than 100 μm from a blood supply, cancer cells must initiate the formation of new blood vessels to support their growth via the process of "sustained angiogenesis". During the development of most cancers, primary tumor cells acquire the ability to undergo "invasion and metastasis" whereby they migrate into the surrounding tissue and travel to distant sites in the body, forming secondary tumors. The pathways that cells take toward becoming malignant cancers are variable, and the order in which the hallmarks are acquired can vary from tumor to tumor.
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Hyraxes share several unusual characteristics with mammalian orders Proboscidea (elephants and their extinct relatives) and Sirenia (manatees and dugongs), which have resulted in their all being placed in the taxon Paenungulata. Male hyraxes lack a scrotum and their testicles remain tucked up in their abdominal cavity next to the kidneys, the same as in elephants, manatees, and dugongs. Female hyraxes have a pair of teats near their armpits (axilla), as well as four teats in their groin (inguinal area); elephants have a pair of teats near their axillae, and dugongs and manatees have a pair of teats, one located close to each of the front flippers. The tusks of hyraxes develop from the incisor teeth as do the tusks of elephants; most mammalian tusks develop from the canines.
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He notes that in most mammalian species the only known function of the clitoris is to generate sensation during copulation, but saw no evidence that "the female genitals of any mammalian species have been designed by natural selection for efficiency in orgasm production." He criticizes Elizabeth Sherfey's view that the female orgasm is an adaptation, writing that her arguments are not supported by ethnographic or biological evidence. Symons proposes that male human ancestors lost the ability to detect ovulation in females by smell because females gained a reproductive advantage by concealing ovulation, and that estrus ceased to exist in humans at the same time. Observing that estrous female chimpanzees are more successful than nonestrous females in obtaining meat from males, Symons suggests that when hunting became a dominant male economic activity during human evolution, the benefits to females of receiving meat may have outweighed the costs to them of constant sexual activity, leading to women making sexual overtures to men in order to obtain meat.
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