1Laboratory of Fishery Nutritional Science, Graduate School of Marine Science and Engineering, Nagasaki University, Nagasaki 852-8521, 2Laboratory of Fishery Nutritional Science, Graduate School of Fisheries, Nagasaki University, Nagasaki 852-8521, 3Laboratory of Marine Biochemistry, Graduate School of Marine Science and Engineering, Nagasaki University, Nagasaki 852-8521, Japan
Anti-α-actinin IgG was prepared from rat serum immunized with purified α-actinin in the ordinary muscle of red sea bream. Anti-α-actinin IgG showed immune reactivity against not only α-actinin in ordinary muscle but also papain-digests of the α-actinin. According to immunoelectron microscopic method, α-actinin was detected on Z line of ordinary muscle cells and non-specific reactions were not detected on another organelles. The changes of α-actinin in the ordinary muscle of cultured red sea bream during storage in ice were examined by SDS-PAGE followed by its immunoblotting. It was found that the limited digestion of α-actinin in ordinary muscle of cultured red sea bream started on day one in ice, then, native α-actinin was not detected on day 5 and 7. These results suggested that the weakening of Z-disks in ordinary muscle was caused by the disappearance of α-actinin and resulted in the softness of the flesh texture of cultured red sea bream.