Thermotolerance of a long-lived mutant of Caenorhabditis elegans.

Age-synchronous cohorts of Caenorhabditis elegans were grown at 20 degrees C, then stressed at 30 degrees C or 35 degrees C. Intrinsic thermotolerance of wild type and age-1 mutant strains was assessed by measuring either progeny production or survival. In addition to increased life span (Age), mutation of age-1 results in a highly significant increased intrinsic thermotolerance (Itt) as measured by survival at 35 degrees C. Mean survival of Age strains is approximately 45% longer than that of non-Age strains for both sterile and nonsterile worms. Thermotolerance declines across the life span of both Age and non-Age strains, but Itt was observed at almost all ages. Unstressed age-1 animals showed a consistent and significant fertility deficit. Short thermal stresses can cause a dramatic reduction in progeny production for both Age and non-Age genotypes. Mutants of age-1 showed a small but consistent increased thermotolerance as measured by fertility. We propose that the enhanced ability of Age strains to cope with environmental stress may be mechanistically related to their lower age-specific mortality rates.