SEATTLE, Aug. 4 /PRNewswire/ -- Scientific dogma has long asserted that females are born with their entire lifetime's supply of eggs, and once they're gone, they're gone. New findings by researchers at Fred Hutchinson Cancer Research Center, published online Aug. 27 in Science, suggest that in nematode worms, at least, this does not hold true.
Molecular physiologist Marc Van Gilst, Ph.D., and colleagues report that during starvation, sexually mature adult worms stop ovulating and the germline component of their reproductive system - the sex cells, including mature and maturing eggs - dies off and leaves behind nothing but a few stem cells. However, once normal food conditions resume, the conserved stem cells can produce a brand new crop of sex cells, complete with youthful and fertile eggs.
This turning back of the reproductive clock all takes place in tiny C. elegans soil worms that are up to 15 times older than normally fed worms in their reproductive prime.
"For many, it has been assumed that cells and organs remain relatively stable during periods of starvation or caloric restriction," said Van Gilst, an assistant member of the Hutchinson Center's Basic Sciences Division, who authored the study with postdoctoral research fellow Giana Angelo, Ph.D. "The idea that an entire system would kill itself off during starvation and then regenerate upon food restoration was very surprising. The fact that extremely old worms could generate new eggs and produce healthy offspring long after their normally fed counterparts had reproduced and died was also unexpected," he said.
The mechanism behind the preservation and extension of fertility long past the worms' normal reproductive prime, Van Gilst suspects, is a signaling receptor protein in the cell nucleus called NHR-49, which promotes a major metabolic response to dietary restriction and fasting. While it has been hypoth
|SOURCE Fred Hutchinson Cancer Research Center|
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