THERMOTOLERANCE AND EXTENDED LIFE-SPAN CONFERRED BY SINGLE-GENE MUTATIONS AND INDUCED BY THERMAL-STRESS

We have discovered that three longevity mutants of the nematode Caenor habditis elegans also exhibit increased intrinsic thermotolerance (Itt ) as young adults. Mutation of the age-1 gene causes not only 65% long er life expectancy but also Itt. The Itt phenotype cosegregates with a ge-1. Long-lived spe-26 and daf-2 mutants also exhibit Itt. We investi gated the relationship between increased thermotolerance and increased life-span by developing conditions for environmental induction of the rmotolerance. Such pretreatments at sublethal temperatures induce sign ificant increases in thermotolerance and small but statistically highl y significant increases in life expectancy, consistent with a causal c onnection between these two traits. Thus, when an animal's resistance to stress is increased, by either genetic or environmental manipulatio n, we also observe an increase in life expectancy. These results sugge st that ability to respond to stress limits the life expectancy of C. elegans and might do so in other metazoa as well.