Magierecka 2023 Abstract IOC160

Magierecka A, McLennan D, Dawson N, Millet C, Metcalfe NB (2023) Sustained swimming performance is independent of organism-level and mitochondrial-level metabolism in European minnows. Mitochondr Physiol Network 28.01.

Link: IOC160

Magierecka A, McLennan D, Dawson N, Millet C, Metcalfe NB (2023)

Event: IOC160

Metabolic rate is a fundamental trait that influences and constraints the behaviour and performance of animals. However, conventional measures of metabolic rate, based on whole-animal oxygen consumption, often fail to show the predicted relationships with measures of animal performance since it is unclear what proportion of consumed oxygen is associated with ATP production. Thus the efficiency with which the mitochondria convert oxygen into ATP can be a better determinant of an animal performance capacity. In this study we examined whether mitochondrial efficiency predicts sustained swimming performance in the European minnow (Phoxinus phoxinus), a riverine fish. We measured individual critical swimming speed (Ucrit) followed by a measurement of maximum metabolic rate (MMR), standard metabolic rate (SMR) and mitochondrial function, predicting that measures of mitochondrial performance such as the ATP produced per molecule O2 consumed will be positively related to Ucrit and that the variation in Ucrit explained by mitochondrial function will be greater than any explained by MMR and SMR. Maximal rates of oxidative phosphorylation at the mitochondrial level were positively correlated with maximal oxidative metabolism of the whole fish. However, contrary to our predictions, swimming performance was unrelated to both organism-level and our measures of mitochondrial level metabolism, with Ucrit, MMR and SMR being influenced by individual body mass only. This suggests that, while mitochondrial function predicts whole-animal metabolism, it does not necessarily constrain animal locomotor performance, and the maximum sustained swimming speed is not determined by energy or oxygen supply. Further research is needed to determine the limits to physical performance.

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Labels: MiParea: Respiration 

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