Development of intestinal brush border aminopeptidase in the larval japanese flounder Paralichthys olivaceus

In the present study, immunohistochemical methods have been used to localize aminopeptidase on the intestinal brush border of Japanese flounder Paralichthys olivaceus with a view to tracing the changes in digestive function of the intestinal brush border that occur during the larval stage. Aminopeptidase was purified from the intestinal brush border of adult red seabream Pagrus major, and an anti-aminopeptidase antibody (anti-rAmp) prepared. Because the anti-rAmp recognized the aminopeptidases of four species of fish but not those of zooplankton, it was applied to flounder larvae. The intestinal epithelial cells of the flounder were found to have already begun to synthesize aminopeptidase before hatching and to possess nearly complete capability at 2 day-post-hatching, i.e., 1 day prior to exogenous feeding.