The long-term effects of a life-prolonging heat treatment on the Drosophila melanogaster transcriptome suggest that heat shock proteins extend lifespan

Heat-induced hormesis, i.e. the beneficial effect of mild heat-induced stress, increases the average lifespan of many organisms. This effect, which depends on the heat shock factor, decreases the log mortality rate weeks after the stress has ceased. To identify candidate genes that mediate this lifespan-prolonging effect late in life, we treated flies with mild heat stress (34°C for 2h) 3 times early in life and compared the transcriptomic response in these flies versus non-heat-treated controls 10–51days after the last heat treatment. We found significant transcriptomic changes in the heat-treated flies. Several hsp70 probe sets were up-regulated 1.7–2-fold in the mildly stressed flies weeks after the last heat treatment (P