Females with a mutation in a nuclear-encoded mitochondrial protein pay a higher cost of survival than do males in Drosophila

Males and females age at different rates in a variety of species, but the mechanisms underlying the difference is not understood. In this study, we investigated sex-specific costs of a naturally occurring mildly deleterious deletion (ΔTrp85, ΔVal86) in cytochrome c oxidase subunit 7A (cox7A) in Drosophila simulans. We observed that females and males homozygous for the mutation had 30% and 26% reduced Cox activity, respectively, compared with wild type. Furthermore, 4-day-old females had 34%-42% greater physical activity than males. Greater physical activity in mutant females was correlated with a 19% lower 50% survival compared with wild-type females. Mutant and wild-type males had equal survival. These data suggest that females paid a higher cost of the mutation than did males. The data demonstrate linking population genetics and structural modeling to experimental manipulations that lead to functional predictions of mitochondrial bioenergetics and organism aging.