Postmortem grass carp (Ctenopharyngodon idella) muscle towards the disruption of integrity: a likely cause of abnormal regulation of tight junction and decreased antioxidant capacity

The disruption of structural integrity could affect flesh quality changes. This study investigated the disruption of muscle integrity and the affecting factors in postmortem fish at 4 degrees C for 5 days storage. Haematoxylin-eosin staining indicated that profound disruption of structural integrity was observed for the changes of dissolved nucleus, irregular shape of myofibrils and loose attachment. The increased activities of beta-N-acetyl-glucosaminidase (NAG) and alpha-Glucosidase (AG) enzymes confirmed the profound disruption of integrity in postmortem muscle. The abnormal up-regulated gene expressions of claudin-11, claudin-12, claudin-15a, claudin-15b and myosin light chain kinase (MLCK) implied the disrupted intercellular integrity. The impaired cellular integrity and the increased oxidative damage was due to the decreased antioxidant capacity, which was regulated by the decreased transcriptional levels of antioxidant enzymes. Collectively, this study provided a partial molecular mechanisms for the disruption of structural integrity and the changes of flesh quality in postmortem fish muscle.

Automated summary

This study found that the disruption of structural integrity in postmortem fish muscle can affect flesh quality changes. The changes observed in dissolved nucleus, irregular shape of myofibrils, and loose attachment indicate the profound disruption of muscle integrity. The up-regulated gene expressions and decreased antioxidant capacity contribute to the disrupted intercellular integrity and increased oxidative damage.