Proteomic approach to probe for larval proteins of the mussel Mytilus galloprovincialis

A proteomic approach was used to search for larval proteins specific to the mussel Mytilus galloprovincialis from Galicia in northwest Spain. The study included both a comparative analysis, through two-dimensional electrophoresis, of protein expression maps of the larvae of the mussel and of 5 abundant and commercially important bivalve species from the region (Ostrea edulis, Cerastoderma edule, Pecten maximus, Tapes decussatus, and Venarupis pullastra) and subsequent mass spectrometric analysis of some of the protein spots. A total of 18 spots were selected and isolated from gels of M. galloprovincialis larvae. From their relative position on the electrophoresis gels, 6 of these were clearly exclusive to the mussel species. However, it was not clear whether the other spots were shared by other species. To overcome this ambiguity, first an analysis using matrix assisted laser desorption ionization with time-of-flight (MALDI-TOF) was conducted on the 6 spots of Mytilus that could possibly be shared with only one species. The peptide mass fingerprinting was completely different for the proteins compared. This result confirmed that the 6 proteins were exclusively mussel proteins, but demonstrated the utility of this approach when working with species that are poorly represented at the protein level in databases.