Meeting Abstract

S9.1-5  Tuesday, Jan. 7 09:40  Nutrient flux through glycolysis and gluconeogenesis and the evolution of cold-stress tolerance in Drosophila melanogaster. WILLIAMS, C.M.*; SUNNY, N.; EDISON, A.S. ; MORGAN, T.J.; HAHN, D.A.; U. Florida, Gainesville; U. Florida, Gainesville; U. Florida, Gainesville; Kansas State U., Manhattan; U. Florida, Gainesville carolinewilliams@ufl.edu

Ectotherms must maintain energy homeostasis in rapidly changing thermal conditions; a considerable challenge given that metabolism comprises a complex suite of processes that differ in their thermal sensitivities. Cold-adaptation on a broad phylogenetic scale involves changes to enzymes and pathways that allow them to function more effectively at low temperatures, but we lack an understanding of the microevolutionary variation in energy metabolism segregating within populations that may contribute to cold-stress tolerance. Without an integrative understanding of this naturally segregating variation, from the genomic through the physiological to the organismal levels, we cannot predict the evolvability of cold-stress tolerance, an important component of predicting the impacts of global climate change. We hypothesize that susceptibility to cold stress is set by an imbalance between energy supply and demand incurred at low temperatures, and that resistance may be conferred by reorganizing metabolic networks to maintain energy balance more effectively at low temperatures. Using complementary resources of the Drosophila melanogaster Genetic Reference Panel (192 fully-genotyped isogenic lines), and Drosophila lines selected in the laboratory for fast or slow recovery from a cold-induced coma, we show that tolerant flies have higher metabolic rates, maintain metabolic homeostasis more effectively during cold exposure, and show considerable restructuring of metabolic networks. Using stable isotopes, we demonstrate a reallocation of nutrients among core energetic pathways. These alterations to nutrient flux may rebalance energy supply and demand in the cold, and assist in maintaining energy balance in the face of changing temperatures.