Carbonic Anhydrase and Otolith Formation in the Rainbow Trout, Salmo gairdneri: Enzyme Activity of the Sacculus and Calcium Uptake by the Otolith in Vitro

Abstract

The involvement of saccular carbonic anhydrase (CA) in otolith formation was studied in cultivated rainbow trout. CA activity was electrometrically determined in the sacculus, gill, and blood. In vitro calcium uptake by the otolith in sacculus-otolith preparations was also examined in the presence and absence of Diamox. The sacculus contained CA in a concentration of 95 EU per g-wet tissue after correction for blood contamination. This activity was completely inhibited by Diamox. The gill and the blood had much higher CA activities of 1391 EU per g and 1544 EU per ml, respectively. In organ culture, the otolith showed a calcium uptake of 15.7xl0-3μg per mg-dry tissue after 48 h of incubation. Diamox significantly inhibited this uptake, by 21 %.>These results were discussed in terms of the functional involvement of saccular CA in the car-bonate formation of fish otoliths. © 1979, The Japanese Society of Fisheries Science. All rights reserved.