Evidence and cellular localization of an oxidative activity in the coelomic fluid of the earthworm Eisenia fetida andrei

Abstract

An oxidative activity was evidenced in the coelomic fluid of the earthworm Eisenia fetida andrei, when l-DOPA was used as substrate. Oxidative activity, measured by optical density due to dopachrome formation, was found to be optimal at basic pH (9–10). Changes in the rate of substrate conversion observed after the addition of hydrogen peroxide or catalase suggest that oxidation of l-DOPA by E. fetida andrei coelomic fluid is mediated by both oxidasic and peroxidasic systems. Microscopy studies, using substrates for the determination of both phenoloxidase and peroxidase activities, demonstrated that the enzyme(s) is localized in chloragocyte vesicles called chloragosomes. The persistence of a remnant staining after incubation with phenoloxidase inhibitors as well as with peroxidase inhibitors strengthened the hypothesis of a synergistic activity of two oxidative systems in E. fetida andrei coelomic fluid.