The Influence of Characteristics of Actomyosin on the Difference of Rigor Mortis Progress between Cultured and Wild Red Sea Bream

Abstract

As part of a study program to clarify the cause of differences in rigor mortis progress between cultured and wild red sea bream, the superprecipitation reaction, the Mg²⁺-ATPase activity, and the Ca²⁺-sensitivity of actomyosin Mg²⁺-ATPase were measured at several Ca²⁺ and ATP concentrations, and these discrepant points were examined between cultured and wild fish. The superprecipitation reaction became higher with the increase of Ca²⁺ concentration from pCa 7.0 to pCa 5.0 and higher with the decrease of ATP concentration from 3.0mM to 0.5mM in both cultured and wild fish; the level was lower in cultured fish than in wild fish. In both the Mg²⁺-ATPase activity and the Ca²⁺-sensitivity, similarly changing aspects were observed, but the level was higher in cultured fish than in wild fish, contrary to expectations. Therefore, although a significantly positive correlation was found between the superprecipitation reaction and the Mg²⁺-ATPase activity in both cultured and wild fish, the distributive position of both values was clearly different between cultured and wild fish and the superprecipitation reaction was lower in cultured fish than in wild fish when the Mg²⁺-ATPase activity was the same level. These results suggest that the characteristics of actomyosin corresponding to muscular contraction might be remarkably different between cultured and wild red sea bream.