Article Dans Une Revue Ecological and Evolutionary Physiology Année : 2025

Sexual dimorphism in red blood cell mitochondrial respiration during breeding fasts in king penguins

Résumé

Because of their extended fasting period on land during breeding male king penguins have been extensively studied to unravel the physiological adaptations that enables them to fast while having to find a partner, defend their territory, or brood their offspring. While the different phases of fasting and the nature of the metabolic fuels used are well characterised in male king penguins, fewer studies have focused on the efficiency of the conversion of the metabolic resources into energy at a cellular-level, through mitochondrial respiration.

1 Furthermore, little information is available in females in general while they experience fasting periods as well. Here, we measured mitochondrial respiration rates of red blood cells (RBCs) at the beginning (3 days) and at the end (10 days) of a natural egg-incubation fast in male and female king penguins. We tested if (1) RBC mitochondrial metabolism and its efficiency are modulated by fasting duration in free-living king penguins, but also (2) assess if this modulation is sex-specific. In response to fasting, the respiration allocated to ATP synthesis in RBCs decreased in both sexes. Interestingly, RBC mitochondrial metabolic rates were higher in females at any stage of fasting. Furthermore, RBC mitochondrial metabolism efficiency decreased in males after 10 days of fasting, while it remained constant in females.

Our results demonstrate that RBC mitochondrial metabolism is context and state-dependent, differing between sexes and changing with fasting. They underline the importance of taking both sexes into account in physiological studies, where females remain under-represented.

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hal-05141332 , version 1 (03-07-2025)

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Nina Cossin-Sevrin, Céline Bocquet, Camille Lemonnier, Thomas Faulmann, Natacha Garcin, et al.. Sexual dimorphism in red blood cell mitochondrial respiration during breeding fasts in king penguins. Ecological and Evolutionary Physiology, 2025, 98 (2), pp.96-110. ⟨10.1086/736013⟩. ⟨hal-05141332⟩
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