Effects of temperature on myofibrillar ATPase activities of two lobster species

Abstract

In order to clarify the effects of habitat temperatures on crustacean myofibrillar ATPase activities, the activities were measured in the muscle of American lobster Homarus americanus and Japanese spiny lobster Panulirus japonicus. Magnesium (Mg2+)-ATPase activities of the Japanese spiny lobster in the presence and absence of calcium (Ca2+) were lower than the corresponding activities of the American lobster. The American lobster lost Ca2+ sensitivities in myofibrillar Mg2+-ATPase activities over 35°C, while the Japanese spiny lobster lost sensitivities over 40°C. Inactivation profiles in Mg2+- and Ca2+-ATPase activities showed that myofibrillar thermal stability of the American lobster was lower than that of the Japanese spiny lobster. No seasonal change in Mg2+-ATPase activity was observed in either species. These results suggest that the myofibrils of both lobster species would adapt to their habitat temperatures.