The role of the stress response is to mitigate stress-induced damages and to allow a restoration of cellular homeostasis

1Scientific RepoRts | 6:33667 | DOI: 10.1038/srep33667

www.nature.com/scientificreports

Thermal stress depletes energy reserves in Drosophila Peter Klepsatel, Martina Gáliková, Yanjun Xu & Ronald P. Kühnlein

Understanding how environmental temperature affects metabolic and physiological functions is of crucial importance to assess the impacts of climate change on organisms. Here, we used different laboratory strains and a wild-caught population of the fruit fly Drosophila melanogaster to examine the effect of temperature on the body energy reserves of an ectothermic organism. We found that permanent ambient temperature elevation or transient thermal stress causes significant depletion of body fat stores. Surprisingly, transient thermal stress induces a lasting “memory effect” on body fat storage, which also reduces survivorship of the flies upon food deprivation later after stress exposure. Functional analyses revealed that an intact heat-shock response is essential to protect flies from temperature-dependent body fat decline. Moreover, we found that the temperature-dependent body fat reduction is caused at least in part by apoptosis of fat body cells, which might irreversibly compromise the fat storage capacity of the flies. Altogether, our results provide evidence that thermal stress has a significant negative impact on organismal energy reserves, which in turn might affect individual fitness.

Temperature is ecologically the most important physical factor that has significant effects on the physiology of organisms, particularly ectotherms1, and which is a key determinant of species geographical distribution and abundance2. Thus anthropogenic global warming, which proceeds at an unprecedented rate, presents a consid- erable challenge for many species3. Organisms have to adapt not only to the rising mean temperatures but also to more pronounced short-term temperature fluctuations4. Accuracy of the estimates of biotic changes in response to climate change is thus dependent on our understanding of how thermal stress affects animal physiology.