Limitted degradation of alpha-actinin in the ordinary muscle of cultured red sea bream during storage in ice

Anti-alpha -actinin IgG was prepared from rat serum immunized with purified alpha -actinin in the ordinary muscle of red sea bream. Anti-alpha -actini n IgG showed immune reactivity against not only alpha -actinin in ordinary muscle but also papain-digests of the alpha -actinin. According to immunoel ectron microscopic method, alpha -actinin was detected on Z line of ordinar y muscle cells and non-specific reactions were not detected on another orga nelles. The changes of alpha -actinin in the ordinary muscle of cultured re d sea bream during storage in ice were examined by SDS-PAGE followed by its immunoblotting. It was found that the limited digestion of alpha -actinin in ordinary muscle of cultured red sea bream started on day one in ice, the n, native alpha -actinin was not detected on day 5 and 7. These results sug gested that the weakening of Z-disks in ordinary muscle was caused by the d isappearance of alpha -actinin and resulted in the softness of the flesh te xture of cultured red sea bream.