饥饿对生物体的影响可持续数代

Starvation early in life can alter an organism for generations to come, according to a new study in roundworms. The effects are what Duke University biologist Ryan Baugh terms a "bet-hedging strategy." In nature, the worms live a boom-or-bust lifestyle in which the occasional famine will devastate the population, but not all of the worms are killed. The survivors are smaller and less fertile, and they acquire a toughness that lasts at least two generations. 

What changes isn't their genes themselves, but the way in which those genes are used, Baugh said.

Baugh and his Duke team starved thousands of C. elegans worms for one or eight days at the first stage of larval development after hatching. When feeding was resumed, the worms that had starved longer grew more slowly, and ended up smaller and less fertile. They also proved more susceptible to a second bout of starvation. 

The starved worms also had offspring that were smaller, fewer and less fertile. However, these children and grandchildren of famine turned out to be more resistant to starvation and a heat-tolerance test. More of them were also male instead of the usual hermaphroditic, self-fertilizing form.

In their natural conditions, it appears the worms are able to increase their growth rate and fertility in times of plenty and then to turn these traits back down in hard times. "They have a memory of famine," Baugh said. The net result is "a combination of fitness costs and benefits that unfolds over generations," the authors wrote in a study that appears early online in the journal Genetics. 

Thousands of the 1-millimeter worms were hand-sorted multiple times for the meticulous study. "Phenotypic analysis is a lot of work," Baugh said.