MARRON, M.T.; MARKOW, T.A.; KAIN, K.J.; GIBBS, A.G.*: Effects of stress on energy metabolism in Drosophila.

Laboratory selection experiments have indicated that energy metabolism is an important focus of stress resistance in Drosophila melanogaster. Selection for starvation resistance results in increased lipid storage, and desiccation selection results in increased carbohydrate storage. This suggests that different energetic substrates are used when fruitflies are exposed to different stresses. To test this hypothesis, we assayed lipid and carbohydrate levels in 5 species of Drosophila exposed to either desiccation (no food or water) or starvation (water, but no food). Starved flies metabolized both substrates, with lipid accounting for two-thirds of overall ATP production, whereas desiccated flies relied almost entirely on glycogen metabolism. A broader comparison of 13 species revealed that desert Drosophila had higher levels of both lipids and carbohydrates than mesic species. These fruitflies live in an arid environment with a patchily distributed, ephemeral food source (necrotic cacti), and therefore may be exposed to both desiccation and starvation stress in nature. Supported by the Center for Insect Science and by NSF awards IBN-0110626 (AGG) and DEB-9510645 (TAM).