Bioenergetic consequences of sex-specific mitochondrial DNA evolution

Doubly uniparental inheritance (DUI) represents a notable exception to the general rule of strict maternal inheritance (SMI) of mitochondria in metazoans. This system entails the coexistence of two mitochondrial lineages (F- and M-type) transmitted separately through oocytes and sperm, thence providing an unprecedented opportunity for the mitochondrial genome to evolve adaptively for male functions. In this study, we explored the impact of a sex-specific mitochondrial evolution upon gamete bioenergetics of DUI and SMI bivalve species, comparing the activity of key-enzymes of glycolysis, fermentation, fatty acid metabolism, tricarboxylic acid cycle, oxidative phosphorylation and antioxidant metabolism. Our findings suggest reorganized bioenergetic pathways in DUI gametes compared to SMI gametes. This generally results in a decreased enzymatic capacity in DUI sperm with respect to DUI oocytes, a limitation especially prominent at the terminus of the electron transport system. This bioener...