Hsp83 and TotC are Required for Pathogen-Induced Hormesis in the Fruit Fly

Author(s): McClure CD, Zhong W, Priest NK

Summary:

Hormesis contradicts the fundamental evolutionary concept that organisms can’t have it all. Many studies have found that treatments, such as limited stress and diet restriction, can enhance Darwinian fitness without obvious costs. This is a problem for our understanding of trade-offs as it suggests both that organismal fitness is sub-optimal, and that organisms can avoid trade-offs between life history traits. However, few studies have considered the possibility that hormesis is driven by a trade-off between Darwinian fitness and pathogen resistance. Here we show that topical treatment with an inactive fungus increases the survival and fecundity of various strains of the fruit fly. Using mutant strains and the Gal4::UAS knockdown system, we show that the heat shock protein Hsp83, and the generalist stress gene TotC, are required for this response. Preliminary evidence suggests that this hormetic response depends both on the temperature and diet of the host. These results are important as they identify the genetic basis of a novel hormetic response and provide a potential explanation for phenomena which appear to defy the constraints apparent in life history trade-offs: that hormetic responses are only beneficial under a narrow range of ecological conditions. Thus, our results are consistent with the hypothesis that hormesis also involves trade-offs.

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