Two Modes Of Aging Discovered In Fruit Flies

When food, particularly protein, is in limited supply, female medflies slip into a survival mode, delaying reproduction even until an advanced age. But as soon as a complete diet is available, they shift into high gear, producing eggs and aging rapidly.

"The findings suggest that reproduction may be one of the key pacemakers of aging," says UC Davis insect demographer James R. Carey. Results from the study of 2,500 medflies will be published in the Aug. 14 issue of the journal Science.

Carey and colleagues compared the fertility and life span of medflies receiving a diet of only sugar to those receiving a complete diet including protein, which is crucial for reproduction and often difficult for medflies to find in the wild.

"One of the most notable findings was that in the sugar-only group, even 4- to 5-month-old medflies--the equivalent of 90-year-old humans--could produce a moderate number of eggs once protein was added to their diet," says Carey, currently at the Max Planck Institute for Demographic Research in Rostock, Germany.

The researchers suggest that further studies of the physiological shifts that occur between the waiting and reproductive modes in medflies may yield a better understanding of the fundamental processes that determine longevity.

UC Davis statistics professors Hans-Georg Mueller and Jane-Ling Wang collaborated with Carey on the project, funded by the National Institute on Aging and the National Science Foundation.