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


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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Copyright 2017 The Authors Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0)

DOI: doi:10.3389/fphys.2017.00909


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, mitochondria, proton leak, lesser hedgehog tenrec, endothermy, protoendotherm, cold acclimatization
Research Division:Biological Sciences
Research Group:Biochemistry and cell biology
Research Field:Cell metabolism
Objective Division:Environmental Management
Objective Group:Other environmental management
Objective Field:Other environmental management not elsewhere classified
UTAS Author:Polymeropoulos, ET (Dr Elias Polymeropoulos)
ID Code:122379
Year Published:2017
Web of Science® Times Cited:4
Deposited By:Sustainable Marine Research Collaboration
Deposited On:2017-11-13
Last Modified:2018-04-12
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