養殖マダイと天然マダイの氷蔵中における普通筋の微細構造と細胞化学的Ｍｇ｀２＋´‐ＡＴＰａｓｅ活性の変化

Abstract

We made a comparative study on changes of ultrastructure and cytochemical Mg2+-adenosine triphosphatase (Mg2+-ATPase) in ordinary muscle of cultured and wild red sea bream during storage in ice.Degeneration of the Z lines of ordinary muscle was faster in cultured fish than in wild fish. In cultured fish, the structure of the Z lines became discontinuous within 1 day in ice. While, the Z lines showed continuity until day 3 in wild fish. Degenerations of other organella, such as the sarcoplasmic reticulum, mitochondria, A band, and I band were similar in both cultured and wild fish.Mg2+-ATPase activity was found at the sarcoplasmic reticulum, near both ends of A band, mitochondria, and nuclear membrane in both fish immediatedly after death. Mg2+-ATPase activity in these organella became undetectable on day 5 in cultured fish, but it was still weakly detected on day 7 in wild fish.These results suggested that ultrastructure and cytochemical Mg2+-ATPase activity are good indicators for post-mortem changes in fish muscle.