title: Thermal sensitivity and phenotypic plasticity of cardiac mitochondrial metabolism in European perch, Perca fluviatilis.
abstract: Cellular and mitochondrial metabolic capacity of the heart has been suggested to limit performance of fish at warm temperatures. We investigated this hypothesis by studying the effects of acute temperature increases (16, 23, 30, 32.5 and 36°C) on the thermal sensitivity of 10 key enzymes governing cardiac oxidative and glycolytic metabolism in two populations of European perch (Perca fluviatilis) field-acclimated to 15.5 and 22.5°C, as well as the effects of acclimation on cardiac lipid composition. In both populations of perch, the activity of glycolytic (pyruvate kinase and lactate dehydrogenase) and tricarboxylic acid cycle (pyruvate dehydrogenase and citrate synthase) enzymes increased with acute warming. However, at temperatures exceeding 30°C, a drastic thermally induced decline in citrate synthase activity was observed in the cold- and warm-acclimated populations, respectively, indicating a bottleneck for producing the reducing equivalents required for oxidative phosphorylation. Yet, the increase in aspartate aminotransferase and malate dehydrogenase activities occurring in both populations at temperatures exceeding 30°C suggests that the malate-aspartate shuttle may help to maintain cardiac oxidative capacities at high temperatures. Warm acclimation resulted in a reorganization of the lipid profile, a general depression of enzymatic activity and an increased fatty acid metabolism and oxidative capacity. Although these compensatory mechanisms may help to maintain cardiac energy production at high temperatures, the activity of the electron transport system enzymes, such as complexes I and IV, declined at 36°C in both populations, indicating a thermal limit of oxidative phosphorylation capacity in the heart of European perch.
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, 41390 Gothenburg, Sweden andreas.ekstrom@bioenv.gu.se.
authors.forename: Andreas
authors.initials: A
authors.lastname: Ekström
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, 41390 Gothenburg, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Sandblom
authors.affiliation: Department of Biology, University of Québec, Rimouski, Québec, Canada G5L 3A1.
authors.forename: Pierre U
authors.initials: PU
authors.lastname: Blier
authors.affiliation: Department of Biology, University of Québec, Rimouski, Québec, Canada G5L 3A1.
authors.forename: Bernard-Antonin
authors.initials: BA
authors.lastname: Dupont Cyr
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, 41390 Gothenburg, Sweden.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Brijs
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, 41390 Gothenburg, Sweden.|Department of Biology, University of Québec, Rimouski, Québec, Canada G5L 3A1.|Department of Chemistry and Biochemistry, University of Moncton, Moncton, NB, Canada E1A 3E9.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Pichaud
mesh_terms: D000064:Acclimatization; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D002950:Citrate (si)-Synthase / Q000378:metabolism; D002952:Citric Acid Cycle; D005227:Fatty Acids / Q000032:analysis / Q000378:metabolism; D029941:Fish Proteins / Q000378:metabolism; D057232:Global Warming; D006019:Glycolysis; D006358:Hot Temperature; D050356:Lipid Metabolism; D008055:Lipids / Q000032:analysis; D008928:Mitochondria / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism; D010084:Oxidation-Reduction; D010471:Perches / Q000502:physiology*; D013696:Temperature
chemical_list: D000596:Amino Acids; D005227:Fatty Acids; D029941:Fish Proteins; D008055:Lipids; D002950:Citrate (si)-Synthase
keywords: Citrate synthase; Fatty acid oxidation; Lipid composition; Temperature acclimation; Tricarboxylic acid cycle