SUNDAY, July 21 (HealthDay News) -- Researchers have made the surprising finding that the "female" X chromosome may have an important function in sperm production.
Women have two X chromosomes and men have an X and Y chromosome. This study found that large portions of the X chromosome have evolved to play a specialized role in producing sperm.
And despite its reputation as the most stable chromosome of the genome, the X chromosome has actually been undergoing relatively rapid changes, according to the study published online July 21 in the journal Nature Genetics.
Taken together, these two findings suggest that it's time to reexamine the biological and medical importance of the X chromosome, said the researchers at the Whitehead Institute for Biomedical Research in Cambridge, Mass.
"We view this as the double life of the X chromosome," Whitehead director David Page said in an institute news release.
"The X is the most famous, most intensely studied chromosome in all of human genetics. And the story of the X has been the story of X-linked recessive diseases, such as color blindness, hemophilia, and Duchenne's muscular dystrophy," Page noted. "But there's another side to the X, a side that is rapidly evolving and seems to be attuned to the reproductive needs of males."
In the study, the researchers compared mouse and human X chromosomes and found that they had nearly 95 percent of their X-linked, single-copy genes in common. Nearly all these genes are expressed in both sexes.
But the study also identified about 340 genes that are not shared between mice and humans. Most of these genes are active almost exclusively in testicular germ cells where they likely contribute to sperm production.
"These genes are more likely to have roles in diseases that are related to reproduction, infertility, perhaps even testis cancer. There's a whole other book to be written about this aspect of the X," Page noted in the news release.
The U.S. National Library of Medicine has more about chromosomes.
SOURCE: Whitehead Institute for Biomedical Research, news release, July 21, 2013
be well, feel better
Spring cleaning can help you drop the pounds and keep them off.
Talks every man must have with his doctor.
Follow these tips to kick any bad habit.
You don't need heavy weights for a great workout. You just need a great workout for the weights you have. That's why I created this 20-minute, fat-shredding routine that you can do with just a pair of 5- or 10-pound dumbbells. The best way to describe it: gut-busting.
It's totally possible to rediscover that zest and optimism you felt when you were younger.
Strong social connections are good for your health. Take steps to nurture existing friendships as well as to expand your social circle.
Heart disease is the leading cause of death in U.S. women. Here's what you need to know.
Busy women share their tips for staying mentally and physically energized.