Comparative analysis of macaque and human sperm proteomes: Insights into sperm competition.

Male macaques produce faster sperm than male humans due to a higher pressure of sperm competition in macaques. To explore the molecular basis of this biological difference, we firstly constructed macaque and human sperm proteomes using LC-MS/MS. We then detected the positively selected genes specifically on the branch of macaque based on branch-site likelihood method. We identified 197 positively selected genes specifically on the branch of macaque that are unselected in corresponding human orthologs. These genes are highly associated with mitochondria and axoneme that directly drive sperm motility. We further compared the ultrastructural differences of the midpiece between macaque and human sperms to provide evidence for our findings using transmission electron microscopy. In conclusion, our results provide potential molecular targets for explaining the different phenotypes under sperm competition between macaques and humans, and also provide resources for the analysis of male fertility.