Meeting Abstract

48.5  Saturday, Jan. 5  Evolution of Two Genomes: Impact of Sequence Divergence on Mitochondrial Function BARIS, T.Z.*; OLEKSIAK, M.F.; CRAWFORD, D.L.; University of Miami/Rosenstiel School of Marine and Atmospheric Science tbaris@rsmas.miami.edu

We are investigating the divergence in oxidative phosphorylation (OxPhos) metabolism among populations of Fundulus heteroclitus. The OxPhos pathway occurs in mitochondria and uses oxygen to produce the majority of ATP in a cell. This pathway consists of 5 large enzyme complexes with 45 to 4 proteins per complex and is the only pathway in which the proteins involved are coded by both mitochondrial and nuclear genomes. F. heteroclitus populations have sequence divergence in OxPhos genes in both mitochondrial and nuclear genomes. These populations are distributed along a steep thermal cline on the east coast of the United States and have evolved by natural selection to adapt to this clinal variation in temperature. Thus, F. heteroclitus serve as a model species to enhance our understanding of the impact of nucleotide divergence on physiological function. The initial studies of OxPhos function used 96 individuals from six different populations of F. heteroclitus, and differences in mitochondrial respiration were measured using a high-resolution respirometer (Oxygraph-2k, Oroboros Instruments, Innsbruck, Austria). The fish from each population were acclimated to both 12°C and 28°C. Hearts were isolated from each individual, permeabilized, and assayed at 3 different temperatures (12°C, 20°C, and 28°C). Total mitochondrial respiration and individual enzyme complexes of oxidative phosphorylation were measured by addition of complex specific substrates and poisons. Differences among populations and temperatures will provide insights into the evolution and adaptation of natural populations.