A detailed analysis of the just-completed sequence of the human Y chromosome — the chromosome that distinguishes males from females — has uncovered a novel mechanism by which it maintains its genetic integrity. The study is published in the current issue of Nature.
All other chromosomes occur in pairs and preserve genetic integrity by exchanging information with matching genes on the homologous chromosome, a process called “crossing over.” But the Y chromosome lacks that option, being the only chromosome that is unpaired. Instead, the Y appears to exchange genes between the two arms that make up the chromosome itself.
This phenomenon, called gene conversion — the non-reciprocal transfer of genetic information from one DNA molecule to another — has been previously observed on a small scale over long evolutionary timescales between repeated sequences on the same chromosome, but not at the dramatic frequency apparently employed by the Y chromosome.
For more information, go to: Nature
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