Linking paternally inherited mtDNA variants and sperm performance

Area of Science:

• Evolutionary Biology
• Genetics
• Reproductive Biology

Background:

• Mitochondrial DNA (mtDNA) variants impact reproductive success and male fertility.
• Strict maternal inheritance (SMI) can lead to 'mother's curse' where detrimental male fertility haplotypes persist.
• Doubly uniparental inheritance (DUI) in bivalves offers a unique model to study sex-specific selection on mtDNA.

Purpose of the Study:

• To investigate the impact of mtDNA variants on sperm performance and bioenergetics in DUI and SMI species.
• To evaluate how direct selection on sperm mitochondria contributes to male reproductive fitness.
• To understand the adaptive value of mtDNA variation in relation to male energetic adaptation and fertilization success.

Main Methods:

• Comparative analysis of sperm performance and bioenergetics in DUI and SMI bivalve species.
• Assessment of sperm function under inhibited energy pathways.
• Evaluation of sperm response to oocyte presence.

Main Results:

• DUI sperm exhibited lower speed and linearity compared to SMI sperm.
• DUI sperm relied strictly on oxidative phosphorylation (OXPHOS) for energy production.
• DUI sperm showed a partial metabolic shift towards fermentation upon egg detection.

Conclusions:

• DUI provides a unique system to study sex-specific selection on mitochondria.
• mtDNA variation is linked to male energetic adaptation, influencing fertilization success.
• Findings suggest mechanisms for paternal mitochondria preservation in DUI systems.