Paternally-inherited mtDNA variants and sperm performance

Poster session
Partie de:
vendredi 20 déc. 11:30 AM (1 heure)
Dîner   12:30 PM à 01:30 PM (1 heure)
Salle ABCD

The selective neutrality of mitochondrial DNA (mtDNA) is nowadays strongly undermined. Studies on reproductive fitness indicate that specific mtDNA haplotypes strongly affect sperm motility and fertility, while having feeble effect on females. Because of the strict maternal inheritance (SMI) of mitochondria, mtDNA variants that are deleterious for male fitness, but with positive or even neutral effect on females can be retained in a population, a phenomenon known as “Mother’s curse”. A stable exception is the doubly uniparental inheritance (DUI) of mitochondria in bivalves. This system entails two mtDNA lineages that evolves independently and are transmitted separately through oocytes and sperm. This makes DUI an exclusive model to evaluate the result of direct selection on sperm mitochondria and its contribution to the reproductive fitness of males. In this study, we tested how maternal and paternal mtDNA variants impact bivalve sperm performance and bioenergetics in multiple DUI and SMI species of bivalves. Variation was also tested following inhibition of the main metabolic pathways, as well as after the introduction of oocyte-derived chemoattractants. Unlike SMI, DUI sperm displayed i) low speed and marked curvilinear trajectory, ii) a strict OXPHOS-dependent strategy of energy production and iii) a partial shift towards fermentation after oocyte detection. Discussion embraces the adaptive value of mtDNA variation and suggests a link between energy metabolism and the preservation of paternal mitochondria in DUI species.

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