Carbonic anhydrase activity and biomineralization process in embryos, larvae and adult blue mussels Mytilus edulis L.

To decide whether a physiological role can be attributed to enzymatic activity with respect to crystal formation and biomineralization of the first larval shell, carbonic anhydrase (CA) activity was measured in embryos and larvae of the blue mussels Mytilus edulis L. Also, CA activity was determined in the mantle edge and gonads of adult mussels with different shell length and condition index. The intention was to find a possible correlation between CA activity and adult shell calcification, i.e. gonadal maturation. The comparison of CA activity in different developmental stages of mussels and the results of an X-ray diffraction study of biomineralization processes in embryonic and larval shells indicate that CA activity is maximal at the end of several developmental stages. Consequently, the increase in CA activity precedes some physiological changes, i.e. the somatoblast 2d formation and the occurrence of the first calcite and quartz crystals in embryos, shell field formation in the gastrula stage, shell gland and periostracum production in trochophores, and rapid aragonite deposition in larval prodissoconch I and prodissoconch II shells. Furthermore, it was found that in adult mussels CA activity was quite variable and that in the mantle edge it was frequently inversely related to the activity in the gonad. Received: 28 November 1998 / Received in revised form: 30 August 1999 / Accepted: 31 August 1999