Fish mucus stimulates the generation of superoxide anion by Chattonella marina and Heterosigma akashiwo

Chattonella marina and Heterosigma akashiwo are highly toxic red tide phyto plankton which causes severe damage to fish farming. Recent studies demonst rated that these flagellates release superoxide anion (O-2(-)) under normal growth conditions. In the present study, we examined the effects of the fi sh mucus prepared from skin and gill of yellowtail, red sea bream, and japa nese flounder on the production of O-2(-) by the flagellates. All mucus tes ted stimulated C, marina and H. akashiwo to generate increased amounts of O -2(-) in a concentration dependent manner. Thus, the common substances pres ent in fish mucus of three species may be responsible for the stimulation o f the flagellates. In the presence of 100 mu g/ml of each mucus, 4-6-fold i ncreased level of O-2(-) was detected in both flagellates. After the heat t reatment (at 121 degrees C for 15 min), no significant decrease of stimulat ory effects of the mucus was observed, suggesting that heat-stable componen ts of the mucus may produce the stimulatory effect on the flagellates. Our results suggest the possibility that the fish mucus enhances the oxygen rad ical-mediated toxic effects of C. marina and H, akashiwo.