Carbonic Anhydrase Activity and Calcium Deposition During the Molt Cycle of the Blue Crab Callinectes Sapidus

Carbonic anhydrase (CA) activity in the epidermis of the blue crab Callinectes sapidus increases significantly during ecdysis, and remains elevated during the postmolt stages. Branchial enzyme activity increases prior to the molt in the posterior gills; in the anterior gills CA activity parallels that in the epidermis. Calcium deposition, as measured by the incorporation of 45Ca into the cuticle, begins in the late premolt stages and increases thereafter. Acetazolamide did not inhibit Ca uptake by the isolated epidermis over a 4-h period in our experiments. Thus, while CA appears to be important to the molt cycle in general, the role of CA in shell deposition is not clear.