Why do men and women play different roles in evolution?
Nature prefers to experiment with the variability of traits on males, and females are "responsible" for the stability and transmission of successful traits to the next generations of the species. One of the mechanisms of this is that during the formation of spermatozoa, the probability of recombination of genes is much greater than that of eggs.
The mechanism of chromosome recombination (the exchange of sites that occurs during the formation of germ cells) is one of the driving forces of variability – an increase in the diversity of traits. New combinations of genes (and, accordingly, variants of phenotypes) allow species to adapt and evolve in constantly changing environmental conditions.
Researchers of the biopharmaceutical company deCODE genetics have identified two single nucleotide polymorphisms in the human genome – "snip", (from the English single nucleotide polymorphism, SNP), regulating the process of recombination.
It turned out that two snips in the RNF212 gene, located on the fourth chromosome, increase the likelihood of chromosome recombination during sperm formation, and reduce it during egg formation. Perhaps this unexpected feature is one of the mechanisms that ensure the appearance of a pronounced diversity of traits in the male part of the population that is less valuable for the survival of the species and at the same time restraining the rate of change in the beautiful half of the biological species.
The researchers identified the SNPs they described as a result of a genome-wide analysis of more than 300,000 SNP genomes of more than 20,000 participants in the company's gene research program. SNPs encoded as rs3796619 and rs1670533, according to the authors, are responsible for about 22% of genomic variations formed as a result of recombination of paternal genes, and for 6.5% of variations in egg genomes. The mammalian RNF212 gene has not been studied well enough, but it is known that it is a homologue of the ZHP-3 gene, which provides recombination in the germ cells of other organisms.
According to Kari Stefansson, executive director of deCODE genetics, the company plans to include the identification of these and other SNPs identified by the company's specialists in deCODEme, its proposed program for the analysis of individual genomes.
deCODE genetics specialists have made a number of discoveries in the field of studying the mechanisms of recombination, fertility and human evolution. In 2002, the company published the most detailed map of genome recombinations at that time, showing the "hot" and "cold" recombination points of all chromosomes, as well as the fact that the location of these points in men and women is very different. This map has greatly facilitated the work on creating the final version of the human genome sequence. After that, the company's specialists demonstrated that the level of recombination differs for different families and different women, that the level of recombination increases with the age of the mother, and that its high values correlate with fertility. In 2005, the company announced the identification of a genetic variant associated with a high level of recombination, which turned out to be the first hereditary trait to be affected by positive evolutionary selection in the modern human population.
Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of ScienceDaily.
08.02.2008