The Y chromosome in primates, including humans, is evolving much more rapidly than the X chromosome, suggests a new study of six primate species.
For example, humans and chimpanzees 98% of DNA Although common across the genome, only 14% to 27% of the DNA sequence on the human Y chromosome is shared with our closest living relatives.
The discovery surprised scientists, given that humans and chimpanzees diverged only seven million years ago, a mere blink of an eye in evolutionary terms.
“Evolutionarily speaking, a significant amount of time has passed, so I expect my genome to be very different from bacterial and insect genomes,” said the study’s co-author. Brandon Pickett“But we would expect it to be pretty similar in other primates,” the postdoctoral researcher at the National Institutes of Health’s National Human Genome Research Institute (NHGRI) told Live Science.
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It’s unclear exactly why the Y chromosome is evolving so rapidly. For starters, there is only one copy of the Y chromosome per cell. In primates, females have two X chromosomes and males have one X and one Y chromosome. The Y chromosome plays a key role in sperm production and reproduction. Having only one Y chromosome creates vulnerability; there is no second chromosome to act as a backup if a change occurs.
And change teeth This is likely due to something called mutation bias. The Y chromosome may be more prone to change because it produces more sperm. This requires a lot of DNA replication. And every time DNA is copied, there’s a chance that mistakes can be introduced.
Scientists have so far Primate Genome for All 16 representative families.
A new study published May 29 in the journal Neurology & Neurology, Nature, Scientists compared the sex chromosomes of five species of apes. Chimpanzee (Pan troglodytes), bonobo (Pan Paniscus), Western lowland gorilla (Gorilla Gorilla Gorilla Bornean orangutan and Sumatran orangutan (Pongo pygmaeus and Pongo Aberi) — and our more distant relative, the siamang (Symphalangus syndactylus).
The team studied the chromosomes using telomere-to-telomere (T2T) sequencing, which can precisely sequence repetitive elements, including the telomere “caps,” the protective layer of chromosomes that has previously been difficult to decipher, Pickett said. Using computer software, the researchers compared the sequencing results and created alignments to reveal which parts of the chromosomes have changed and which haven’t.
The sequences of chromosomes X and Y from each of the six species were also compared with the previously sequenced human chromosomes X and Y. Previous researchUses the T2T method.
The results show that the Y chromosome evolved rapidly in all the species studied, with even species in the same genus having very different Y chromosomes from each other. For example, chimpanzees and bonobos, who diverged only one to two million years ago, have dramatic differences in the length of their Y chromosomes, the researchers said. Christian Ruthand senior scientist at the Institute of Primate Genetics at the German Primate Center, who was not involved in the study.
In some cases, length differences caused by chromosomal losses or duplications during DNA copying accounted for about half of the observed differences. For example, The Sumatran orangutan’s Y is twice as long as that of the gibbon. Chromosome.
In contrast, the study found that the X chromosome is highly conserved across primate species, as would be expected for a structure that plays a key role in reproduction.
One reason the Y chromosome appears to thrive despite its high mutation rate is that in all species studied, the Y chromosome contains highly repetitive genetic material, including palindromic repeats (sequences that read the same both ways). These regions of repeated DNA are where genes reside. Thus, the repetitive DNA may protect important genes from replication errors, thereby preserving important biological material, the researchers write in their paper.
But the study had limitations: It looked at only one representative of each primate species, so it couldn’t say how much Y chromosome variation exists among animals of the same species, Pickett said.