Kingdom of reproductive life; core sperm proteome

Reproductive biology is often considered in the three siloed research areas, namely humans, domesticated animals and wildlife. Yet, there are common needs across these silos, notably treatment of subfertility, biomarkers for fertility/gamete selection, development of assisted reproductive technologies and effective contraception. To efficiently develop solutions applicable to all species, we must improve our understanding of the common biology underpinning reproductive processes. Accordingly, here, we performed an in-silico analysis of publicly available sperm proteomic data across 12 vertebrate species to consolidate these proteomic data and to define the core sperm proteome; a collection of highly conserved proteins that are critical for sperm structure and function. Over 2TB of RAW mass spectrometry data was sourced from ProteomeXchange and processed through a stringent and uniform search protocol to provide high confident protein identifications (FDR ≤ 0.01). A total of 13,853 proteins residing in the sperm of those species studied herein were identified, with the most significant contributions to this inventory being from humans and mice. Proteomic characterisation of non-traditional model species revealed >90% of their sperm proteins are currently curated as predicted to exist or inferred from homology, indicating that experimental evidence for their existence remains poorly defined. Despite variations in sperm proteome size, pathway analyses showcased functional relationships between species that differed from that of their evolutionary distances. Moreover, we report proteins that are highly conserved at the species (45 proteins) and order (135 proteins) taxonomic levels. Such proteins, in turn, mapped to critical pathways and molecular functions including protein folding and recycling, acrosome function and energy generation. In addition, we demonstrated that despite the fundamental biological role of spermatozoa, differing physiological adaptations such as alterations in sperm metabolic preferences, external testes or even a history of selective breeding, are reflected in differences in the sperm proteome