Describing the Ionoregulatory Changes that Underlie Cold Acclimation in Drosophila Melanogaster

At low temperatures Drosophila lose the ability to regulate ion and water balance across the gut leading to a lethal accumulation of K+ in the haemolymph (hyperkalemia). Cold-acclimation can mitigate these ion imbalances, but the physiological mechanisms that facilitate this process are still not understood. Upon adult emergence, D. melanogaster females were subjected to seven days at 25C (warm-acclimation) or 10C (cold-acclimation). Cold-acclimation reduced the critical thermal minimum (CTmin), sped up recovery from chill coma, improved survival following cold stress, and mitigated cold-induced hyperkalemia. In parallel, cold-acclimated flies experienced increased Malpighian tubule fluid and K+ secretion and reduced rectal K+ reabsorption. These changes were independent of Na+/K+- or V-type H+-ATPases. These results suggest that modification of Malpighian tubule and gut mitigate cold-induced hyperkalemia. Additionally, I present preliminary findings on the effects of acclimation, sex, and blood-feeding on the cold tolerance of the arboviral disease vector mosquito, A. aegypti.