Geneticists have found that allows Tibetans to survive at high altitude
People living on the highest mountain plateau in the world, the Tibetan plateau, has developed a unique adaptation for survival in such conditions. Analyzing the largest sample of genomes of local residents, the scientists found, what kind of mutation is responsible for enhanced oxygen transfer and resistance to high doses of ultraviolet radiation.
Working with the results published in the journal PNAS.
Long known that the population of the Tibetan plateau, including the commonly known as Alpine conductors Sherpas who successfully live in a low 40% relative to sea level oxygen content in the air.
An ordinary man acklimatiseras to a great height temporary increase of the hemoglobin level, however, the Tibetans have other adaptations. It plays into their hands, as the high content of hemoglobin hampers the blood pumping and increases the likelihood of blood clots that can lead to stroke and other heart diseases.
In previous studies it was found that the genes EPAS1, inherited by Tibetans from Denisovsky person and ELGN1 involved in the regulation of the exchange of oxygen.
To determine the role of other genes, a group led by Jian Yang from the University of Queensland in Australia studied the genomes of Tibetans and 3008 7287 representatives of other Nations. The scientists looked for common among the inhabitants of the highlands of gene variants and assess the probability of their distribution in the population by chance or natural selection. The genes EPAS1 and ELGN1 predictable turned out to be strong candidates for evolutionary adaptation. Also, this group got the genes MTHFR, RAP1A, NEK7, ADH7, FGF10, HLA-DQB1 and HCAR2.
The ADH7 gene the Tibetans are associated with increased weight and higher values of body mass index that may contribute to survival in terms of lack of resources.
MTHFR increases the production of folic acid, a vitamin, collapsing under the action of ultraviolet radiation. Increased production of this substance should compensate for the higher doses of UV rays from the Sun at high altitude. HLA-DQB1 belongs to the group of genes regulating important immune system proteins, which may be an adaptation to extreme conditions, like malnutrition.
The role of other gene variants remains unclear — perhaps they appeared as an evolutionary response to selective pressures not associated with living at high altitude.