Biologists have a preliminary version of the genome of domestic yak and found that these animals and their owners — people highlands of Tibet — got the same mutation in the same gene that allowed them to adapt to living at high altitude, according to an article published in the journal Nature Genetics.
It is believed that high-altitude animals developed a range of accessories for cellular and genetic level, allowing them to overcome the harsh climate and the lack of food and oxygen at high altitude. In particular, domestic Tibetan yak (Bos grunniens) have large lungs and heart, well oriented in space, their circulatory system is adapted to low levels of oxygen, and metabolism — a constant lack of food.
A team led by Jian-Quan Liu (Jianquan Liu) from the University of Lanzhou (China) made a preliminary version of the genome of a yak, compared it with similar sequences for the next of kin of yaks — domestic cows and identified "high mountain" mutations in the genome of yaks.
According to biologists, the genome consists of yak 2.657 million nucleotides — "building blocks" of DNA, which is comparable to the size of the genome domestic cow — 2.649 million bases. According to researchers, a yak and cow genomes coincide approximately 94%, which confirms their close family ties. According to scientists, yaks and cows divided about 4.9 million years ago.
The resulting sequence of nucleotides comprises 22.2 thousand genes encoding "instructions" for the assembly of proteins. About 100 of them were unique to the yak and do not occur in the genomes of a cow, man or dog. According to scientists, these genes are responsible for the immune system and sense of smell.
The researchers then compared the structure of genes in the genomes of Tibetans, cows and yaks, trying to discover the adaptation to living at high altitude.
The comparison showed that Tibetan yaks and got about the same set of "high" mutations, absent in normal domestic cows. Thus, the genomes of yaks and their hosts contain similar mutations in Adam17, control the metabolism of the body in a lack of oxygen.
In addition, the four-legged symbol of Tibet received some useful changes in gene Camk2b, allowing him to digest green vegetation and benefit from more nutrients.
The researchers believe that the ancestors of yaks and their owners have reacted in a similar way to relocate to Tibet and become identical mutations that are useful for survival in the high mountains.
Scientists believe that their study will help to better understand the causes of altitude sickness and other disorders associated with living on the unusually high altitude.