Proteomic analysis of muscle tissue from gilthead sea bream (Sparus aurata, L.) farmed in offshore floating cages

Characterization of the muscle tissue proteome is key to many aspects of fish aquaculture, encompassing physiology, growth, food safety, seafood authentication and quality, traceability and shelf-life. In this study, a 2D-PAGE-MS study was performed on gilthead sea bream (Sparus aurata, L.) muscle tissue along the production cycle in four offshore floating cage plants and two repopulation lagoons located in different areas of Sardinia, Italy. The aim of this study was to accomplish systematic characterization of the gilthead sea bream muscle proteome, and to gather data about its variability in physiological conditions occurring in both farmed and wild fish. In general, a relatively stable protein expression pattern was observed in farmed sea bream muscle compared to othermore dynamic tissue proteomes, such as liver. However, several statistically significant variations in abundance of some proteins and their isoforms were detected, related to growth and environmental factors. Among these, parvalbumins, troponins, and Wap65 showed variations according to fish length and water temperature. Interestingly, the ratio of structural proteins versus glycolytic enzymes was also observed to change during the production cycle, showing an increase with fish length. In order to assess whether the farming conditions were able to induce alterations in the muscle proteome, farmed and wild fish were subjected to a differential proteomics analysis. The data gathered in this study indicate that the protein expression profile of muscle tissue is comparable in wild and maricultured gilthead sea breams of commercial size, supporting the view that farming in offshore floating cages might favor proper muscle tissue development, and therefore enable the production of higher quality fish. In conclusion, this work describes the detailed characterization of the sea bream muscle proteome, and provides a number of insights on its size and environment-related variability.