Qualitative Shotgun Proteomics Strategy for Protein Expression Profiling of Fish Otoliths

Despite decades of research on fish otoliths and their capacity to serve as biochronological recorders, much remains unknown about protein composition, the mechanisms by which proteins are incorporated into otolith matrix, or potential for using provide insight aspects life history. We examined composition Atlantic cod (Gadus morhua) a state-of-the-art shotgun proteomics approach with liquid chromatography coupled an electrospray ionization-orbitrap tandem mass spectrometer. In addition previously known matrix proteins, we discovered over 2000 not identified in more than 1500 any otoliths. These included three novel (Somatolactin, F-actin-capping subunit beta, Annexin) primarily involved binding calcium ions likely mediating crystal nucleation. However, most were necessarily related formation but rather other physiology. For example, sex-related biomarkers males (SPATA6 protein) females (Vitellogenin-2-like protein). highlight some noteworthy classes having diverse functions; however, primary goal here is discuss each separately. The number roles suggest that could reveal critical history information from archived collections be invaluable understanding biology population ecology. This proof-of-concept methodology paper provides whereby can further explored.