Chitinase and Carbonic Anhydrase Activities during Molting Cycle of Mud Crab (Scylla serrata Forskal 1775)

Abstract

Optimum conditions for the activities of chitinase and carbonic anhydrase in gill, integument and haemolymph of mud crab (Scylla serrata Forskal 1775) were determined. The maximum activity of chitinase in all 3 types of tissue was observed at pH 11 and 40^oC. However, optimum conditions for
carbonic anhydrase in gill, integument and haemolymph were at pH 7.6 at 50^oC, pH 7.2 at 50^oC and pH 7.2 at 60^oC, respectively. Both chitinase and carbonic anhydrase activities varied during various stages of molting. For chitinase, activity in gill at 2-day premolt was significantly lower (P<0.01) than that at 6 hr to 5-day postmolt but not significantly (P<0.01) different from that at intermolt. Maximum chitinase activity in integument observed at 24 hr postmolt was significantly higher (P<0.01) than that at intermolt and early premolt. Chitinase activity in haemolymph was quite stable during premolt and postmolt but significantly lower than that at intermolt (P<0.01). Observation of carbonic anhydrase activities in gill and integument revealed significantly higher activity after molting than during intermolt and premolt stages. Maximum activity of carbonic anhydrase in gill and integument was evident at 6 hr and 5-day postmolt, respectively. For haemolymph, the level of carbonic anhydrase activities during various stages of molting cycle were highly significantly different (P<0.01). The results indicated important roles of chitinase and carbonic anhydrase at every stage in molting cycle of mud crab.