Post Date December, 02 2023
American scientists have recently completed the gene sequencing of the human Y chromosome and found that the sex chromosome, which has always been considered fragile, is more capable of self-protection than people think. This achievement has enhanced people's understanding of male infertility and contributed to the study of better diagnostic and treatment methods.
Scientists from the Whitehead Biomedical Research Institute of Massachusetts Institute of Technology and the University of Washington School of Medicine reported in the British journal Nature to be published on the 19th that the sequencing results showed that there was a unique structure inside the Y chromosome, which enabled it to self repair harmful genetic variations.
The Y chromosome is the chromosome that determines the male sex. Unlike most paired chromosomes, it is a lonely one and has no "partner" to pair with. Because of this, the Y chromosome is not "backup" to each other like the two chromosomes in pairs, which can exchange genetic material, eliminate harmful variations and preserve genes. It is generally believed that the damage of Y chromosome in gene variation is much greater than that of other chromosomes, so it is in degradation, and it is the "graveyard" of gene death. Some scientists even believe that within 5 to 10 million years, human Y staining will become garbage.
However, this gene sequencing found that the Y chromosome contains about 78 protein coding genes, more than the original thought of about 40. More importantly, there are some palindrome structures in the Y chromosome, which can repair genes.
Y chromosome sequencing is helpful to research and treat male infertility
The chromosome is in a double helix. If the two base sequences on the chromosome double strand corresponding to one of the regions are essentially identical, but the sequence is reversed, this region is a palindrome structure. Of the 50 million base pairs of Y chromosome, about 6 million are in palindrome structure. The longest palindrome structure has 3 million base pairs.
The study found that the palindrome structure of Y chromosome contains many genes. Because the two corresponding sequences in the palindrome structure are actually the same, a gene has a copy at both ends of the palindrome structure. In this way, even if there is no paired chromosome of the Y chromosome to exchange genetic material, a "gene transformation" process can be completed internally to repair the gene variation similarly.
Scientists say that the frequency of gene transformation in Y chromosome is as high as that of gene exchange in general chromosomes. Only from father to son, 600 base pairs of Y chromosome will be "rewritten". However, although palindrome structure can repair genes, this repetitive structure also makes genes more susceptible to loss.
Scientists believe that many genes in the palindrome structure of the Y chromosome control testicular development, and the loss of these genes will lead to infertility. It is estimated that one in every thousands of males becomes infertile due to this reason.
