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Mitochondrial proton leak compensates for reduced oxidative power during frequent hypothermic events in a protoendothermic mammal, Echinops telfairi

Citation

Polymeropoulos, ET and Oelkrug, R and Jastroch, M, Mitochondrial proton leak compensates for reduced oxidative power during frequent hypothermic events in a protoendothermic mammal, Echinops telfairi, Frontiers in Physiology, 8 Article 909. ISSN 1664-042X (2017) [Refereed Article]


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DOI: doi:10.3389/fphys.2017.00909

Abstract

The lesser hedgehog tenrec (Echinops telfairi) displays reptile-like thermoregulatory behavior with markedly high variability in body temperature and metabolic rate. To understand how energy metabolism copes with this flexibility, we studied the bioenergetics of isolated liver mitochondria from cold (20C) and warm (27C) acclimated tenrecs. Different acclimation temperatures had no impact on mitochondrial respiration using succinate as the substrate. Mimicking the variation of body temperature by changing assay temperatures from 22 to 32C highlighted temperature-sensitivity of respiration. The 40% reduction of respiratory control ratio (RCR) at 22C compared to 32C, a common estimate for mitochondrial efficiency, was caused by reduced substrate oxidation capacity. The simultaneous measurement of mitochondrial membrane potential enabled the precise assessment of efficiency with corrected respiration rates. Using this method, we show that proton leak respiration at the highest common membrane potential was not affected by acclimation temperature but was markedly decreased by assay temperature. Using membrane potential corrected respiration values, we show that the fraction of ATP-linked respiration (coupling efficiency) was maintained (7085%) at lower temperatures. Collectively, we demonstrate that compromised substrate oxidation was temperature-compensated by the reduction of proton leak, thus maintaining the efficiency of mitochondrial energy conversion. Therefore, membrane potential data suggest that adjustments of mitochondrial proton leak contribute to energy homeostasis during thermoregulatory flexibility of tenrecs.

Item Details

Item Type:Refereed Article
Keywords:thermoregulation, protoendotherms
Research Division:Biological Sciences
Research Group:Biochemistry and Cell Biology
Research Field:Cell Metabolism
Objective Division:Environment
Objective Group:Flora, Fauna and Biodiversity
Objective Field:Flora, Fauna and Biodiversity of environments not elsewhere classified
Author:Polymeropoulos, ET (Dr Elias Polymeropoulos)
ID Code:122379
Year Published:2017
Deposited By:Sustainable Marine Research Collaboration
Deposited On:2017-11-13
Last Modified:2017-11-13
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