Heating stress patterns in Caenorhabditis elegans longevity and survivorship

Survival data from Chenorhabditis elegans strain TJ1060 (spe-9; fer-15) fol lowing brief exposure to 35 degreesC have been investigated. Three experime nts with 3-day-old worms were conducted with heat duration ranging between 0 and 12 hours. A statistically significant increase in life expectancy was observed in the groups heated for less than 2 hours, as compared to the un heated control groups. In different experiments P-values for the observed l ife spans under the hypothesis that heating has no influence on longevity w ere P < 0.004 after 0.5 hour heat, P < 0.012 after 1 hour heat and P < 0.05 5 after 2 hours of heating. A biphasic survival model with Gamma distribute d frailty has been constructed to describe the survival of worms after heat ing. The increase in the remaining life expectancy is determined by more ef fective protection by heat-induced substances in the ages yanger than 27 da ys. The unheated control group demonstrated acquired heterogeneity of frail ty with chronological age while the heat-induced substances defend the worm s in a universal way and protect against the development of frailty.