INHIBITORY EFFECT OF THE IRON CHELATOR DESFERRIOXAMINE (DESFERAL) ON THE GENERATION OF ACTIVATED OXYGEN SPECIES BY CHATTONELLA-MARINA

Recent studies demonstrated that the toxic red tide phytoplankton Chat tonella spp. produce activated oxygen species such as superoxide anion (O-2(-)), hydrogen peroxide (H2O2), and hydroxyl radicals (. OH), whi ch may be responsible for the toxicity of this flagellate. However, th e mechanism behind the production of these oxygen radicals and H2O2 by Chattonella spp. is largely unknown, and the physiological significan ce of activated oxygen species for Chattonella spp. is also unclear. I n the present study, we investigated the involvement of iron in the ge neration of O-2(-) and H2O2 by C. marina. The generation of O-2(-) by C. marina was related to the growth phase: the highest rate of O-2(-) production was observed during the exponential growth phase. However, no such increase during the exponential growth phase was observed in C . marina growing in an iron-deficient medium, even though the growth o f C. marina was not significantly affected by iron-deficiency during t he first 4 d. In addition, the iron chelator desferrioxamine (Desferal ) strongly inhibited the generation of both O-2(-) and H2O2 by C. mari na in a concentration-dependent manner. The growth of C. marina was al so inhibited by Desferal. Furthermore, in the presence of 500 mu M Des feral. C. marina-induced growth inhibition of the marine bacteria Vibr io alginolyticus was almost completely abolished. These results sugges t that iron is required for the generation of activated oxygen species by C. marina, as well as for its own growth.