"Y" Men are better at fixing things!

[aREDSKIN]

Y Chromosome Can Repair Its Own Genes

MALCOLM RITTER

Associated Press

Proving perhaps that nature has a sense of humor, scientists have discovered that the Y chromosome - the one that makes a man a man - has a remarkable ability to make do-it-yourself repairs.

It can fix many of its genes on its own, rather than using the standard technique that involves cooperation between chromosomes.

That ability may help keep the Y chromosome from rotting away over millions of years of evolution. And the discovery might just bring some respect to a hunk of DNA that has been called the Rodney Dangerfield of genetics.

"It now looks like Y chromosomes really have a big trick up their sleeves," said David Page of the Whitehead Institute for Biomedical Research in Cambridge, Mass.

The gene-fixing technique was already known to happen occasionally in humans, but the surprise is that the Y chromosome has elevated it to standard operating procedure.

The work by scientists at the Whitehead Institute and the Washington University School of Medicine in St. Louis appears in Thursday's issue of the journal Nature. It is the first comprehensive and detailed analysis of the genetic code of the Y chromosome.

The work is "a landmark for the history of sex determination," declared Dr. Francis S. Collins, director of the National Human Genome Research Institute.

Men carry one X chromosome and one Y; women have two Xs. Scientists said detailed comparisons between the X and the Y chromosomes could illuminate basic biological differences between the sexes, perhaps shedding light on differences in disease susceptibility, for example.

The gene-repair discovery might also help the Y chromosome shed its bad rep as a genetic wasteland, an uninteresting piece of DNA that cannot maintain itself and so might be headed for doom.

Broken genes tend to erode away over eons. But because most chromosomes are inherited in pairs, with one coming from Mom and the other from Dad, they can swap corresponding pieces of themselves, enabling the species as a whole get rid of damaged genes.

But the Y chromosome comes by itself. It cannot trade appreciable amounts of DNA with its partner, the X chromosome, so it cannot get rid of damaged genes that way. That has led some scientists to regard it as a "rotting chromosome" that might disappear millions of years from now.

The new work found that the Y chromosome follows a do-it-yourself strategy: It carries backup copies of important genes, and it uses one copy to fix flaws in the other.

Page said that ability comes at a price: When the chromosome makes a mistake in the procedure, it can delete stretches of DNA. Such deletions, occurring in one in every few thousand boys, are a recognized cause of male infertility.

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