Changes in the chitinase activity at different stages of red sea bream Pagrus major egg, larva, and juvenile.

概要

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Chitinase activity was detected in the spawned eggs of red sea bream and it increased stepwise with the progress of development. The value of the activity per g egg at the blastula stage in-creased to twice, as high as that of the 4 cell stage. The activity in the course of embryogenesis increased further and just before hatching, the value reached 4.5 times as that of the 4 cell stage. The larval chitinase activity, which was defined as the activity per g larva, began to rise rapidly when feeding commenced. The activity 10 days after hatching increased to about 5 times, as high as that of just after hatching and thereafter the activity fluctuated within a narrow range. The chitinase activity in the juveniles, which was defined as the activity per g tissue for the following organs, stomach, intestine, and pyloric caeca, was constant for the latter two organs throughout the year, although the level in the stomach during the winter season was lowest when compared with the activities in the other seasons. These results suggested that chitinase of red sea bream was synthesized within the egg, and that the synthesis could be induced in the early larval period by the consumption of exogenous foods.