Mutations of Americans

The rate of mutations among Indians and Eskimos is explained

Tape.roo

Geneticists from Harvard Medical School have identified the main types of mutations common among humans. Biologists also named possible causes of these genetic changes in human populations and differences in the rate of their occurrence. A preprint of the article with the results of scientists' research is published in the online repository bioRxiv (Iain Mathieson, David E. Reich, Variation in mutation rates among human populations).

Biologists analyzed the genomes of the main groups of the Earth's population inhabiting North and South America, as well as Eurasia, in order to identify features in genetic changes inherent in each of the populations under consideration. The researchers found that the indigenous peoples of the USA (Indians, Aleuts and Eskimos) are characterized by an increased frequency of substitutions of individual nucleotides near CpG – DNA sites formed by two nucleotides containing cytosine and guanine, respectively. For Europeans and residents of the western part of Eurasia, mutations are the most frequent, as a result of which the three nucleotides of TSS (thymine-cytosine-cytosine) are transformed into TTC.

Scientists suggest that the causes of these two trends are cellular processes that can affect the rate of mutations or the effectiveness of damage repair resulting from deamination of methylated bases. The processes themselves, in turn, are influenced by environmental, genetic and socio-historical factors.

According to the researchers, the results they obtained will help refine existing models of human evolution.

Nucleotides are molecules whose sequences make up DNA. They contain one of the four nitrogenous bases (adenine, guanine, cytosine and thymine) and are designated by the letter corresponding to the base (A, G, C, T). With a single nucleotide substitution, one of the nucleotides is replaced by another, resulting in a point mutation.

Some nitrogenous bases may be methylated, that is, additionally contain a methyl group. As a result, the risk of mutations increases due to deamination - disconnection from the base of the amino group.

Portal "Eternal youth" http://vechnayamolodost.ru  18.07.2016