Investigating the role of mitochondrial membrane potential in paternal inheritance of mitochondria

The process of oxidative phosphorylation (OXPHOS) in mitochondria depends on an electrochemical gradient known as the mitochondrial membrane potential ({Delta}{psi}m). Reflecting high functionality, elevated {Delta}{psi}m usually depicts healthy mitochondria and contribute to organelle selection. This study investigates whether mitochondrial properties linked with bioenergetics, such as {Delta}{psi}m, may play a role in paternal inheritance of mitochondria. More specifically, how sperm {Delta}{psi}m responds to egg chemoattractants in bivalves characterized by distinct mitochondrial inheritance patterns: strict maternal inheritance (SMI) and doubly uniparental inheritance (DUI), the latter displaying sex-specific transmission of paternal mitochondrial DNA (mtDNA). Sperm {Delta}{psi}m was examined in four bivalve species: Mytilus edulis and Ruditapes philippinarum (DUI), plus Mercenaria mercenaria and Mya arenaria (SMI). In absence of oocytes, sperm {Delta}{psi}m did not vary between the two groups. However, we revealed an increase in {Delta}{psi}m following egg detection only in sperm bearing paternally-derived mitochondria (DUI). This suggests, along with bioenergetic changes, that {Delta}{psi}m modulation might be a specific property of DUI paternal mitochondria, possibly implicated in their unique ability to be sex-specifically transmitted.