Molecular biomarkers for flesh quality in farmed Atlantic halibut and cod

The rapid development of molecular biological methods has presented new opportunities for understanding the main causes of poor flesh quality in farmed fish. The calpain/calpastatin system regulates metabolism, protein turnover and myoblast fusion in ske letal muscle. Furthermore through its role in the limited proteolysis of muscle structural proteins the calpain/calpastatin system also has a major role in the post-mortem softening of fish flesh. The first aim of this proposal is to clone full-length cD NAs for key components of the calpain/calpastatin system plus the lysozomal enzyme cathepsin D in halibut and cod. Monoclonal antibodies to these proteins will be produced as tools for future studies on the physiological function and role of the calpain/ calpastatin system in producing soft flesh and gaping in farmed fish. Research in pigs has identified mutations in calpastatin (CAST) as a significant predictor of meat quality. This project will therefore investigate polymorphisms in the CAST gene in fa rmed halibut and cod. The expression patterns of mRNA and protein will be determined in relation to the production cycle with particular reference to the loss of condition associated with winter (halibut) and maturation (cod, male halibut). The effects of season of harvest and feeding regime on the concentrations of calpains and CAST and the autolysis of muscle proteins (release of dystrophin and nebulin) during post-mortem storage will be determined in relation to other flesh quality parameters (texture, pH, water holding capacity, gaping) using multivariate statistical techniques. The research will make a positive contribution to reducing downgrading losses during secondary processing and improving the quality of Norwegian farmed marine fish. This propo sal, builds on our successful NRC Project (1595941/S41) which finish30.9.06, and the "Plan of action 2006": 3.10 Production biology:.Importance of developing molecular markers, 4.1.5 Product quality.