Postmortem Degradation of White Fish Skeletal Muscle (Sea Bass, Dicentrarchus labrax): Fat Diet Effects on In Situ Dystrophin Proteolysis During the Prerigor Stage

Abstract

All during fish postmortem evolution, structural muscle proteins are targets for various proteases. During the prerigor period (24 hours at 4 degrees C for sea bass), cytoskeletal proteins are affected by the first proteolytic events. These cleavages disrupt connections between myofibrils and the extracellular matrix, induce segmentation of myofibril cores, and modify the rheological properties of tissue. Dystrophin, a cytoskeletal actin-binding protein, is a relevant in situ marker for muscular proteolysis in the prerigor period. The immunodetection of dystrophin allowed the monitoring of early proteolysis during fish storage. Using antidystrophin antibodies directed toward the carboxy-terminal region, a highly sensitive domain exposed to calpain activity, we showed that proteolysis kinetics are strongly influenced by the muscular lipid content. In particular, comparison between low-fat diets (11.3% lipid) and high-fat diets (30% lipid), used during sea bass farming (90 days), revealed a faster proteolysis rate during the first 8 hours of storage at 0 degrees C with the high-fat diet. The origin of this faster proteolysis is discussed on the basis of a possible activation or translocation of calpains related to lipid accumulation in muscle fibers and cytoskeleton alterations.

Dystrophin Degradation in Skeletal Muscles with Lipid Enrichment in Cattle

“…This data was also matched with former reports regarding that muscular proteolysis was accelerated during the first 8 hours of storage at 0℃ with the high-fat diet when comparing low-fat diets as a caloric proportion of 11.3% lipid and high-fat diets as caloric proportion of 30% lipid [6]. This faster proteolysis is possibly due to the activation or translocation of calpains, related to lipid accumulation in muscle fibers and cytoskeleton alterations [6].…”

“…Activation of extracellular signal-regulated kinase 1/2 (ERK1/2) but not c-Jun N-terminal kinase-1 or p38 MAP kinase has been noted in the mdx muscle [16]. High fat diet during the farming has also been reported as a faster proteolytic factor, possibly by activation of calpain-related lipid accumulation in muscle fibers with cytoskeletal alterations [6].…”

Effect of thermal treatment on muscle tissue structure and ultrastructure of wild and farmed sea bass, Dicentrarchus labrax L

“…In the present study, the detachment of myofibrils to the sarcolemma shows the early proteolytic activity of the calpains on the costameres such as has been observed on other species (sea bass, Bonnal et al 2001;Ayala et al 2005; farmed cod, Ofstad et al 1996a). In the present work, sarcolemma and endomysium were usually not disrupted in raw samples of wild sea bass, which coincides with the results found in farmed sea bass Ayala et al 2005) and in wild cod (Ofstad et al 1996a).…”

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“…Enzymatic proteolysis of fish meat during post mortem storage cause disruption of the structure of the myofibrillar proteins (Jasra et al, 2001;Verrez-Bagnis et al, 1999) and is thought to cause post-mortem softening, which is one of the most important quality attributes of fish muscle during cold storage. ( Munasinghe et al, 2005;Bonnal et al, 2001;VerrezBagnis et al, 2001;Sompongse et al, 1996). These studies show that the rate of proteolysis varies among species (Papa et al, 1996;.…”