Generation of superoxide anion radicals by the marine phytoplankton organism, Chattonella antiqua

The generation of superoxide anion radical (O 2 −, believed to be a causative factor in the killing of fish by the phytoplankton Chattonella antiqua , has been examined using several methods: electrochemical technique, reduction of ferricytochrome c and fluorescent laser microscope. Evidence is presented to suggest that these organisms release superoxide continuously while they are living, even in the resting state. Additional generation of O 2 − accompanies the discharge of mucocysts, and is triggered when they are exposed to mucus from the gill lamellae of fish. Such instantaneous generation of O 2 − is also induced when the organisms are in contact with an electrode poised at a potential of +0.1 V versus Ag/AgCI, which is positive enough to oxidize O 2 − to O 2 .