Ca2+ATPase, Carbonic Anhydrase and Alkaline Phosphatase Activities in Red Sternum Mud Crabs (Scylla serrata)

Abstract

Red sternum is a poorly understood symptom affecting mud crab aquaculture in Thailand. This work presents the results of enzymatic activities in mud crab exhibiting the red sternum symptom. The enzymatic activities of Ca2+ATPase, carbonic anhydrase and alkaline phosphatase were analyzed in five tissues (muscle, gill, hepatopancreas, integument and hemolymph) from symptomatic and asymptomatic mud crabs. The main features of the symptom include reddish colored stripes on the abdominal thorax, sternum and chelae, swollen hepatopancreas, milky hemolymph and opaque and whitish muscle. The most distinctive change could be observed in the hemolymph which enabled classification of its severity into three groups—group I: translucent brown hemolymph, group II: cloudy orange hemolymph and group III: milky unclotted hemolymph. Ca2+ATPase levels were highest in the muscle of asymptomatic crabs. This enzyme activity tended to increase in all tissues of symptomatic crabs in groups I and II, especially in the gill of group II where it was fivefold higher than in asymptomatic crabs. Carbonic anhydrase and alkaline phosphatase values were highest in the hepatopancreas of asymptomatic crabs. Alkaline phosphatase decreased in all tissues of the three groups of symptomatic crabs. Carbonic anhydrase levels were highly variable with a decreasing trend in most tissues of groups I and II.