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Researchers have known for years that cutting animals' food intake by about one-third extends the creatures' life spans (Science News: 3/15/1997, p. 162: http://www.sciencenews.org/sn_arc97/3_15_97/bob1.htm). Using DNA-coated glass chips, researchers have begun ferreting out the shifting genetic activity that accompanies this drastic dietary effect.

Investigators have now compared the 11,000 genes in the livers of mice eating freely with those in rodents on short-term and long-term diets. Genes implicated in inflammation, cell stress, and other contributors to aging increased their activity in older nondieting mice, Stephen R. Spindler of the University of California, Riverside and his colleagues report in the Sept. 11, 2001 Proceedings of the National Academy of Sciences.

Many of those genes, however, don't boost their activity in aging mice who have been on the calorie-restricted diet for 7 or 27 months, the investigators found. Moreover, old mice placed on the low-cal plan for just 4 weeks had a pattern of genetic activity similar to that of rodents on the diet for much longer periods. This finding suggests that even short-term experiments in mice could unveil new genetic targets relevant to human longevity.