Actin Gene Expression During Muscle Growth in Carcinus Maenas

Abstract

ABSTRACT As in other crustaceans, growth in Carcinus maenas (L.) is closely associated with the moult cycle because of the restrictions imposed by the calcified exoskeleton. The greatest increase in body mass occurs after ecdysis when the old exoskeleton is shed and rates of water uptake are elevated with a consequent increase in body volume (Drach, 1939; Mykles, 1980; Hartnoll, 1982). Growth of the walking leg extensor muscles in crustaceans such as Homarus americanus and Carcinus maenas is achieved both by the addition of sarcomeres to lengthen the muscle fibres and by increasing the number of myofibrils to add to their diameter (Govind, 1982; El Haj et al. 1984; El Haj and Houlihan, 1987). Addition of sarcomeric proteins to the fibres is relatively rapid, being restricted to the few days when ecdysis and the immediate postecdysial stages occur, while increases in fibre diameter may occur over the longer intermoult periods (Houlihan and El Haj, 1985; El Haj and Houlihan, 1987). The factors regulating muscle growth in crustaceans have not been identified and the stages of the moult cycle where regulation occurs have not been defined.