Siberian genes
Siberians' genes have adapted to harsh conditions
Alexandra Fedoseeva, "Science in Siberia"
Genes have been discovered that have helped the indigenous peoples of Siberia adapt to life in a cold climate and a fairly monotonous diet. The study was conducted by a team of scientists from the Arizona and Washington Universities in the USA with the participation of the Institute of Cytology and Genetics SB RAS, the results are published in Molecular Biology and Evolution (Hallmark et al., Genomic Evidence of Local Adaptation to Climate and Diet in Indigenous Siberians).
The indigenous inhabitants of Siberia have found mutations in genes that affect lipid metabolism – a complex process that includes the breakdown, digestion, absorption, transportation and accumulation of fats in the body. Changes occurred in membrane-associated phospholipase A2 (PLA2G2A), perlipin gene (PLIN1) and angiopoietin-like protein 3 (ANGPTL8). DNA samples of Nganasans and Yakuts are mainly included in the work, the data obtained were also confirmed on the material of representatives of 17 more Siberian ethnic groups.
"The study explains the fact that indigenous ethnic groups have very low levels of low-density lipoprotein, that is, "bad" cholesterol. And this is against the background of eating mainly fatty meat food: the usual menu is deer blood, raw meat, fish, a delicacy – raw kidneys, brains," says Lyudmila Pavlovna Osipova, a leading researcher at FITZ ICiG SB RAS, candidate of biological Sciences.
Scientists suggest that the genes found are also involved in the work of brown adipose tissue, or brown fat, since it is he who at the molecular level may be responsible for the low level of bad lipids in the blood. Brown fat is activated in the cold and begins to release energy intensively, which warms a person; at the same time, fat, like wood stoves, needs fatty acids and glucose. People with active brown adipose tissue have lower levels of both total and bad cholesterol, but higher levels of good cholesterol (high-density lipoprotein). If the cold lasts long enough, which is what happens in Siberia, brown fat can require fuel all the time, that is, it constantly burns a lot of lipids. "So far, there are no biochemical and physiological data on the state of drilling adipose tissue in the indigenous population of Siberia, but our study suggests that it should be active," Lyudmila Osipova clarifies.
The staff of the Laboratory of Population Ethnogenetics of the FITZ ICiG SB RAS has been working closely with the University of Arizona for many years. "In recent years we have been adapting the indigenous inhabitants of Siberia, before that there were works on the study of the genetic structure of Siberian ethnic groups – this information was also included in the study," says Lyudmila Osipova. – Our laboratory is the keeper of a unique material: my first expedition was back in 1974, so we have samples of true representatives of the Nganasan and other peoples, who are fewer and fewer due to assimilation. In total, the DNA of sixteen populations (Evenks, Dolgans, Selkups, Nenets, Khanty, Komi, Teleuts and others) is collected here, for each of them there is all the necessary information: gender, age, some diseases, pedigree. These are protected personal data, they do not appear anywhere, but they are necessary for our research."
In addition to the low content of low–density lipoproteins in the blood, the characteristic features of the physiology of the indigenous peoples of Siberia include accelerated metabolism and elevated levels of thyroxine, a thyroid hormone. This, according to the researchers, may also be related to the genes found through the mechanisms of functioning of brown fat: thyroxine activates brown adipose tissue, and increased energy release in it requires enhanced nutrition, which can lead to rapid metabolism. "I remember being struck by the elderly women of the Selkups and Nenets: they have absolutely no excess weight, they are very light on their feet, they walk a lot on the tundra. It's amazing how much energy they have with such thinness. After all, we are used to the fact that there should be some fat reserves in the body, but they do not need to. Their body is constantly fueled by a certain type of nutrition and genetically determined metabolism. It is obvious that adaptation to harsh living conditions and to certain foods are interrelated," says the geneticist.
Unfortunately, the unique mechanism of adaptation turns into a risk factor in our time, when representatives of indigenous peoples switch to the so-called European lifestyle with a different type of diet, including a large amount of carbohydrates. Genotypes that are selected as a result of positive selection and are significant in the traditional way of Siberian ethnic groups are completely unsuited to this. There is often a shift in metabolism, excess weight appears, and with it diseases such as type 2 diabetes mellitus and hypertension (the so-called metabolic syndrome). Scientists hope that further research will help to find a solution to this problem.
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