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EPAS1
Endothelial PAS domain-containing protein 1 (EPAS1, also known as hypoxia-inducible factor-2alpha (HIF-2α)) is a protein that is encoded by the ''EPAS1'' gene in mammals. It is a type of hypoxia-inducible factor, a group of transcription factors involved in the physiological response to oxygen concentration. The gene is active under hypoxic conditions. It is also important in the development of the heart, and for maintaining the catecholamine balance required for protection of the heart. Mutation often leads to neuroendocrine tumors. However, several characterized alleles of ''EPAS1'' contribute to high-altitude adaptation in humans. One such allele, which has been inherited from Denisovan archaic hominins, is known to confer increased athletic performance in some people, and has therefore been referred to as the "super athlete gene". Function The EPAS1 gene encodes one subunit of a transcription factor involved in the induction of genes regulated by oxygen, and which is indu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-altitude Adaptation In Humans
High-altitude adaptation in humans is an instance of evolutionary modification in certain human populations, including those of Tibet in Asia, the Andes of the Americas, and Ethiopia in Africa, who have acquired the ability to survive at altitudes above 2,500 meters. This adaptation means irreversible, long-term physiological responses to high-altitude environments, associated with heritable behavioural and genetic changes. While the rest of the human population would suffer serious health consequences, the indigenous inhabitants of these regions thrive well in the highest parts of the world. These people have undergone extensive physiological and genetic changes, particularly in the regulatory systems of oxygen respiration and blood circulation, when compared to the general lowland population. Around 81.6 million people, approximately 1.1% of the world's human population, live permanently at altitudes above putting these populations at risk for chronic mountain sickness (CMS) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypoxia-inducible Factors
Hypoxia-inducible factors (HIFs) are transcription factors that respond to decreases in available oxygen in the cellular environment, or Hypoxia (medical), hypoxia. They are only present in ParaHoxozoa, parahoxozoan animals. Discovery The HIF transcriptional complex was discovered in 1995 by Gregg L. Semenza and postdoctoral fellow Guang Wang. In 2016, William Kaelin Jr., Peter J. Ratcliffe and Gregg L. Semenza were presented the Lasker Award for their work in elucidating the role of HIF-1 in oxygen sensing and its role in surviving low oxygen conditions. In 2019, the same three individuals were jointly awarded the Nobel Prize in Physiology or Medicine for their work in elucidating how HIF senses and adapts cellular response to oxygen availability. Structure Most, if not all, oxygen-breathing species express the conservation (genetics), highly conserved transcriptional complex HIF-1, which is a heterodimer composed of an alpha and a beta subunit, the latter being a const ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archaic Human Admixture With Modern Humans
There is evidence for interbreeding between archaic and modern humans during the Middle Paleolithic and early Upper Paleolithic. The interbreeding happened in several independent events that included Neanderthals and Denisovans, as well as several unidentified hominins. In Eurasia, interbreeding between Neanderthals and Denisovans with modern humans took place several times. The introgression events into modern humans are estimated to have happened about 47,000–65,000 years ago with Neanderthals and about 44,000–54,000 years ago with Denisovans. Neanderthal-derived DNA has been found in the genomes of most or possibly all contemporary populations, varying noticeably by region. It accounts for 1–4% of modern genomes for people outside Sub-Saharan Africa, although estimates vary, and either none or possibly up to 0.3% — according to recent research — for those in Africa. It is highest in East Asians, intermediate in Europeans, and lower in Southeast Asians. According to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Denisovan
The Denisovans or Denisova hominins ) are an extinct species or subspecies of archaic human that ranged across Asia during the Lower and Middle Paleolithic. Denisovans are known from few physical remains and consequently, most of what is known about them comes from DNA evidence. No formal species name has been established pending more complete fossil material. The first identification of a Denisovan individual occurred in 2010, based on mitochondrial DNA (mtDNA) extracted from a juvenile female finger bone excavated from the Siberian Denisova Cave in the Altai Mountains in 2008. Nuclear DNA indicates close affinities with Neanderthals. The cave was also periodically inhabited by Neanderthals, but it is unclear whether Neanderthals and Denisovans ever cohabited in the cave. Additional specimens from Denisova Cave were subsequently identified, as was a single specimen from the Baishiya Karst Cave on the Tibetan Plateau. DNA evidence suggests they had dark skin, eyes, and hair, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tibetan People
The Tibetan people (; ) are an East Asian ethnic group native to Tibet. Their current population is estimated to be around 6.7 million. In addition to the majority living in Tibet Autonomous Region of China, significant numbers of Tibetans live in the Chinese provinces of Gansu, Qinghai, Sichuan, and Yunnan, as well as in India, Nepal, and Bhutan. Tibetan languages belong to the Tibeto-Burman language group. The traditional or mythological explanation of the Tibetan people's origin is that they are the descendants of the human Pha Trelgen Changchup Sempa and rock ogress Ma Drag Sinmo. It is thought that most of the Tibeto-Burman speakers in Southwest China, including Tibetans, are direct descendants from the ancient Qiang people. Most Tibetans practice Tibetan Buddhism, although some observe the indigenous Bon religion and there is a small Muslim minority. Tibetan Buddhism influences Tibetan art, drama and architecture, while the harsh geography of Tibet has produced an adap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pheochromocytoma
Pheochromocytoma (PHEO or PCC) is a rare tumor of the adrenal medulla composed of chromaffin cells, also known as pheochromocytes. When a tumor composed of the same cells as a pheochromocytoma develops outside the adrenal gland, it is referred to as a paraganglioma. These neuroendocrine tumors are capable of producing and releasing massive amounts of catecholamines, metanephrines, or methoxytyramine, which result in the most common symptoms, including hypertension (high blood pressure), tachycardia (fast heart rate), and diaphoresis (sweating). However, not all of these tumors will secrete catecholamines. Those that do not are referred to as biochemically silent, and are predominantly located in the head and neck. While patients with biochemically silent disease will not develop the typical disease manifestations described above, the tumors grow and compress the surrounding structures of the head and neck, and can result in pulsatile tinnitus (ringing of the ear), hearing loss, au ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Himalayan Wolf
The Himalayan wolf (''Canis lupus chanco'') is a canine of debated taxonomy. It is distinguished by its genetic markers, with mitochondrial DNA indicating that it is genetically basal to the Holarctic gray wolf, genetically the same wolf as the Tibetan and Mongolian wolf, and has an association with the African wolf (''Canis lupaster''). No striking morphological differences are seen between the wolves from the Himalayas and those from Tibet. The Himalayan wolf lineage can be found living in Ladakh in the Himalayas, the Tibetan Plateau, and the mountains of Central Asia predominantly above in elevation because it has adapted to a low-oxygen environment, compared with other wolves that are found only at lower elevations. Some authors have proposed the reclassification of this lineage as a separate species. In 2019, a workshop hosted by the IUCN/SSC Canid Specialist Group noted that the Himalayan wolf's distribution included the Himalayan range and the Tibetan Plateau. The group ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tibetan Mastiff
The Tibetan Mastiff ( bo, འདོགས་ཁྱི, THL: , Wylie: ) * Nepali: * Mongolian: * Hindi/Garhwali/ Kumaoni: * Kashmiri: * Ladakhi: * Dzongkha: is a large size Tibetan dog breed. Its double coat is medium to long, subject to climate, and found in a wide variety of colors, including solid black, black and tan, various shades of red (from pale gold to deep red) and bluish-gray (dilute black), and sometimes with white markings around neck, chest and legs. Name The term ''mastiff'' was assigned by the Europeans who first came to Tibet because that name was used to refer to nearly all large dog breeds in the West. Early Western visitors to Tibet misnamed several of its breeds, such as the Tibetan terrier, which is not a terrier, and the Tibetan spaniel, which is not a spaniel. A better name for the breed might be the ''Tibetan mountain dog'' or—to encompass the landrace breed throughout its range—the ''Himalayan mountain dog''. Description Appearance ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polycythemia
Polycythemia (also known as polycythaemia) is a laboratory finding in which the hematocrit (the volume percentage of red blood cells in the blood) and/or hemoglobin concentration are increased in the blood. Polycythemia is sometimes called erythrocytosis, and there is significant overlap in the two findings, but the terms are not the same: polycythemia describes any increase in hematocrit and/or hemoglobin, while erythrocytosis describes an increase specifically in the number of red blood cells in the blood. Polycythemia has many causes. It can describe an increase in the number of red blood cells ("absolute polycythemia") or to a decrease in the volume of plasma ("relative polycythemia"). Absolute polycythemia can be due to genetic mutations in the bone marrow ("primary polycythemia"), physiologic adaptations to one's environment, medications, and/or other health conditions. Laboratory studies such as serum Erythropoietin, erythropoeitin levels and genetic testing might be helpfu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erythropoietin
Erythropoietin (; EPO), also known as erythropoetin, haematopoietin, or haemopoietin, is a glycoprotein cytokine secreted mainly by the kidneys in response to cellular hypoxia; it stimulates red blood cell production (erythropoiesis) in the bone marrow. Low levels of EPO (around 10 mU/mL) are constantly secreted in sufficient quantities to compensate for normal red blood cell turnover. Common causes of cellular hypoxia resulting in elevated levels of EPO (up to 10 000 mU/mL) include any anemia, and hypoxemia due to chronic lung disease. Erythropoietin is produced by interstitial fibroblasts in the kidney in close association with the peritubular capillary and proximal convoluted tubule. It is also produced in perisinusoidal cells in the liver. Liver production predominates in the fetal and perinatal period; renal production predominates in adulthood. It is homologous with thrombopoietin. Exogenous erythropoietin, recombinant human erythropoietin (rhEPO), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catecholamines
A catecholamine (; abbreviated CA) is a monoamine neurotransmitter, an organic compound that has a catechol (benzene with two hydroxyl side groups next to each other) and a side-chain amine. Catechol can be either a free molecule or a substituent of a larger molecule, where it represents a 1,2-dihydroxybenzene group. Catecholamines are derived from the amino acid tyrosine, which is derived from dietary sources as well as synthesis from phenylalanine. Catecholamines are water-soluble and are 50% bound to plasma proteins in circulation. Included among catecholamines are epinephrine (adrenaline), norepinephrine (noradrenaline), and dopamine. Release of the hormones epinephrine and norepinephrine from the adrenal medulla of the adrenal glands is part of the fight-or-flight response. Tyrosine is created from phenylalanine by hydroxylation by the enzyme phenylalanine hydroxylase. Tyrosine is also ingested directly from dietary protein. Catecholamine-secreting cells use several re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ghost Population
A ghost population is a population that has been inferred through using statistical techniques. Population studies In 2004, it was proposed that maximum likelihood or Bayesian approaches that estimate the migration rates and population sizes using coalescent theory can use datasets which contain a population that has no data. This is referred to as a "ghost population". The manipulation allows exploration in the effects of missing populations on the estimation of population sizes and migration rates between two specific populations. The biases of the inferred population parameters depend on the magnitude of the migration rate from the unknown populations. The technique for deriving ghost populations attracted criticism because ghost populations were the result of statistical models, along with their limitations. Population genetics In 2012, DNA analysis and statistical techniques were used to infer that a now-extinct human population in northern Eurasia had interbred with both th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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