Hydrogen sulfide exposure increases desiccation tolerance in Drosophila melanogaster

Hydrogen sulfide (H₂S) has been shown to effect physiological alterations in several animals, frequently leading to an improvement in survival in otherwise lethal conditions. In the present paper, a volatility bioassay system was developed to evaluate the survivorship of Drosophila melanogaster adults exposed to H₂S gas that emanated from a K₂S donor. Using this bioassay system, we found that H₂S exposure significantly increased the survival of flies under arid and food-free conditions, but not under humid and food-free conditions. This suggests that H₂S plays a role in desiccation tolerance but not in nutritional stress alleviation. To further confirm the suggestion, the mRNA levels of two desiccation tolerance-related genes Frost and Desat2, and a starvation-related gene Smp-30, from the control and treated flies were measured by quantitative real-time PCR. These genes were up-regulated within 2 h when the flies transferred to the arid and food-free bioassay system. Addition of H₂S further increased Frost and Desat2 mRNA levels, in contrast to Smp-30. Thus, our molecular results were consistent with our bioassay findings. Because of the molecular and genetic tools available for Drosophila, the fly will be a useful system for determining how H₂S regulates various physiological alterations.