The Induction of Carbonic Anhydrase in the Symbiotic Sea Anemone Aiptasia pulchella

The activity and nature of carbonic anhydrase (CA, EC 4.2.1.1 .) was measured and described in the tropical sea anemone Aiptasia pulchella. The hypothesis that high CA activity in animal tissue is induced by the presence of symbiotic algae was tested. CA activity was positively correlated with the number of symbiotic dinoflagellates (zooxanthellae) present. CA activity in aposymbiotic anemone tissue was 2.5 times lower than that in control symbiotic animals or in aposymbiotic animals repopulated with algae. Polyclonal antisera against human CA were used to probe for the presence of CA in both symbiotic and aposymbiotic anemone tissue, and in freshly isolated and cultured zooxanthellae. The resulting immunoblots showed one band with a molecular weight of 30 kDa in symbiotic animal tissue and control mammalian CA lanes, no bands in the aposymbiotic animal lanes, and one band at a molecular weight of 22.5 kDa in freshly isolated and cultured zooxanthellae lanes. Because no 22.5 kDa band was detected in the symbiotic animal tissue lanes, the high CA activity found in symbiotic animal tissue is considered to be due to the induction of animal enzyme by the presence of algae. The lack of any band in the aposymbiotic lanes further supports the hypothesis that CA activity in A. pulchella is induced by the presence of algae.