Redox balance and the oxidative stress response following acute heat stress of the early embryo in temperate and tropical lines of Drosophila melanogaster
Authors: Thomas O'Leary; Brent Lockwood
Affiliation: University of Vermont, Burlington, VT
Keywords: p. physiology; a. stress responses
Early embryos are particularly vulnerable to acute heat stress compared to later life stages. But previous work on Drosophila melanogaster has shown that tropical lines are more heat tolerant than temperate lines, suggesting that selection has made tropical embryos more robust to heat stress. Heat-tolerant genotypes more highly express oxidative stress response genes compared to heat-sensitive genotypes. Beyond the clear benefit of limiting the accumulation of reactive oxygen species and oxidative damage, a robust oxidative stress response may be crucial to maintaining redox balance, which has been shown to be important for progression through early embryogenesis. Here, we characterized redox status and oxidative damage in early embryos (0 – 1 hr after egg laying) following acute heat stress. The response of the embryo was measured through (i) the ratio of redox couples (NADH:NAD+ & GSH:GSSG) as an indication of the general redox state, (ii) superoxide dismutase (SOD) activity to quantify the antioxidant response, and (iii) lipid peroxidation to assess the level of oxidative damage. This work aims to elucidate whether the oxidative stress response is a molecular mechanism underlying acute heat tolerance in early embryos, and therefore, whether maintaining redox homeostasis is critical to heat tolerance in D. melanogaster embryos.