Proteome analysis of the fathead minnow (Pimephales promelas) reproductive testes

Proteomics is becoming more widely used as a tool in fish physiology and toxicology and can offer mechanistic insight into organism responses to environmental signals and stressors. Using a LTQ Orbitrap Velos MS/MS, we detected 1075 proteins in the reproductive testis of fathead minnow. Proteins localized to the testis included those with a role in spermatogenesis, DNA repair, gamete meiosis, and proteins that have methylation and phosporylation activity, which are important regulatory mechanisms required for sperm maturation. Enrichment analysis revealed that proteins involved in translation, excision DNA repair, and chromatin remodeling were significantly enriched in the testis (>25% protein coverage of the cellular pathways). Proteins involved in RNA metabolism, spliceosome assembly, metabolism, and DNA unwinding were localized to the testis, and the DEAD (Asp-Glu-Ala-Asp) box RNA-dependent helicase family was well represented in this reproductive tissue. Based upon common detected proteins and functional processes between FHMs and the more ancient sharks, other ray-finned fishes, and mammals, we hypothesize that biological processes involved in the testis (DNA unwinding, RNA processing, spliceosome assembly) have been conserved throughout vertebrate evolution. This study provides the foundation for more in depth proteomics studies investigating the effects of hormones and endocrine disruptors in the teleostean testes.