Convergent changes in muscle metabolism depend on duration of high-altitude ancestry across Andean waterfowl

High-altitude environments require that animals meet the metabolic O2 demands for locomotion and thermogenesis in O2-thin air, but the degree to which convergent metabolic changes have arisen across independent high-altitude lineages or the speed at which such changes arise is unclear. We examined seven high-altitude waterfowl that have inhabited the Andes (3812-4806m elevation) over varying evolutionary time scales, to elucidate changes in biochemical pathways of energy metabolism in flight muscle relative to low-altitude sister-taxa. Convergent changes across high-altitude taxa included increased hydroxyacyl-coA dehydrogenase and succinate dehydrogenase activities, decreased lactate dehydrogenase, pyruvate kinase, creatine kinase, and cytochrome c oxidase activities, and increased myoglobin content. ATP synthase activity increased in only the longest established high-altitude taxa, whereas hexokinase activity increased in only newly established taxa. Therefore, changes in pathways of lipid oxidation, glycolysis, and mitochondrial oxidative phosphorylation are common strategies to cope with high-altitude hypoxia, but some changes require longer evolutionary time to arise

Sirtuin 3 Expression and Acetylation of Three Downstream Targets in Painted Turtle Liver and Brain during Anoxia

The western painted turtle is a champion anaerobe; its anoxia tolerance is heavily enabled by metabolic depression. While cellular metabolism is highly regulated by reversible-acetylation of mitochondrial proteins; this phenomenon is relatively unexamined in the anoxia-tolerant turtle. Sirtuin 3 (SIRT3) is a mitochondrial global deacetylase involved in regulating many metabolic and stress-resistance processes, suggesting a potential role in the control of hypometabolism in the turtle. During early anoxia in the brain and liver, mitochondrial acetylation and SIRT3 protein levels increased. Cyclophilin D levels, a direct target of SIRT3, were also elevated during anoxia. Another target of SIRT3, NF-B p65 exhibited increased deacetylation during anoxia and reoxygenation in the brain; while there was no difference in prevalence or activity of manganese superoxide dismutase, an antioxidant target. This thesis provides preliminary evidence that SIRT3 and mitochondrial protein acetylation may play a role in the regulation of anoxia in the painted turtle.M.Sc