28th ANNUAL EASTERN FISH HEALTH WORKSHOP April 21-25, 2003 Production Of Cytotoxic Oxygen Species By Lobster Hemocytes Robert S. Anderson and Amy E. Beaven University of Maryland Center for Environmental Science, Chesapeake Biological Laboratory, P.O. Box 38, Solomons, MD 20688 Cytotoxic oxyradicals are generated during activation of lobster hemocytes and probably play a role in antimicrobial activities of these cells. These reactive oxygen species (ROS) are typically produced upon activation and assembly of membrane-associated NADPH oxidase and released into phagolysosomes. In this study, the ROS superoxide and hypochlorous acid (HOCl) were quantified by chemiluminescence (CL) using the probes lucigenin and luminol, respectively. Phorbol myristate acetate. (PMA), a classical activator of mammalian NADPH oxidase, strongly stimulated HOCl production; its effect on net superoxide release was minimal, but consistently reduced the time to peak release. A single exposure to PMA elicited total ROS release, because additional exposures were ineffective. Other typical NADPH oxidase stimuli including phagocytosis and a Ca ionophore failed to produce ROS from lobster hemocytes. The results suggested that PMA-stimulated, luminol-dependent CL was a valuable method to assess ROS responsiveness in Homarus americanus. By using various NADPH oxidase activators, it was clear that differences existed between the respiratory burst signal transduction pathways in mammals and lobsters. Return to 28th Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page