Oxidative phosphorylation efficiency, proton conductance and reactive oxygen species production of liver mitochondria correlates with body mass in frogs.
Body size is a central biological parameter affecting most biological processes (especially energetics) and the mitochondrion is a key organelle controlling metabolism and is also the cell's main source of chemical energy. However, the link between body size and mitochondrial function is still unclear, especially in ectotherms. In this study, we investigated several parameters of mitochondrial bioenergetics in the liver of three closely related species of frog (the common frog Rana temporaria, the marsh frog Pelophylax ridibundus and the bull frog Lithobates catesbeiana). These particular species were chosen because of their differences in adult body mass. We found that mitochondrial coupling efficiency was markedly increased with animal size, which led to a higher ATP production (+70%) in the larger frogs (L. catesbeiana) compared with the smaller frogs (R. temporaria). This was essentially driven by a strong negative dependence of mitochondrial proton conductance on body mass. Liver mitochondria from the larger frogs (L. catesbeiana) displayed 50% of the proton conductance of mitochondria from the smaller frogs (R. temporaria). Contrary to our prediction, the low mitochondrial proton conductance measured in L. catesbeiana was not associated with higher reactive oxygen species production. Instead, liver mitochondria from the larger individuals produced significantly lower levels of radical oxygen species than those from the smaller frogs. Collectively, the data show that key bioenergetics parameters of mitochondria (proton leak, ATP production efficiency and radical oxygen species production) are correlated with body mass in frogs. This research expands our understanding of the relationship between mitochondrial function and the evolution of allometric scaling in ectotherms.
Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés, UMR 5023, CNRS, Université de Lyon 1, 69622 Villeurbanne, France damien.roussel@univ-lyon1.fr.
Damien
D
Roussel
Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés, UMR 5023, CNRS, Université de Lyon 1, 69622 Villeurbanne, France Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow G12 8QQ, Glasgow, UK.
Karine
K
Salin
Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés, UMR 5023, CNRS, Université de Lyon 1, 69622 Villeurbanne, France.
Adeline
A
Dumet
Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés, UMR 5023, CNRS, Université de Lyon 1, 69622 Villeurbanne, France.
Caroline
C
Romestaing
Laboratoire de Biométrie et Biologie Évolutive, UMR 5558, CNRS, Université de Lyon 1, 69622 Villeurbanne, France Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg 2193, South Africa.
Benjamin
B
Rey
Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés, UMR 5023, CNRS, Université de Lyon 1, 69622 Villeurbanne, France.
Yann
Y
Voituron
D000818:Animals; D001835:Body Weight / Q000502:physiology*; D004734:Energy Metabolism; D008930:Mitochondria, Liver / Q000737:chemistry / Q000378:metabolism*; D010085:Oxidative Phosphorylation; D011522:Protons; D011898:Ranidae / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*
D011522:Protons; D017382:Reactive Oxygen Species
Allometry; Bioenergetics; Free radicals; Mitochondrial efficiency; Proton leak