BIOLUMINESCENCE AS A POSSIBLE AUXILIARY OXYGEN DETOXIFYING MECHANISM IN ELATERID LARVAE

This work examines the hypothesis that beetle bioluminescent reactions may primarily have evolved to provide an auxiliary O-2 detoxifying me chanism. The activities of antioxidant enzymes and of luciferase in th e prothorax (bright) and abdomen (dim) of luminous larval Pyrearinus t ermitilluminans (Coleoptera: Elateridae) were measured after previous challenge with either hyperoxia, hypoxia, or the firefly luciferase in hibitor luciferin 6'-methyl ether (LME). Upon exposure to pure O-2 for 72 h, the prothorax activities of total superoxide dismutase (SOD) an d catalase were found to increase by 85% and 50%, respectively. Concom itantly, levels of luciferase and luciferin increased 80% and 50%. Ass ays of thiobarbituric acid reactive substances (TEARS) showed signific antly augmented lipid peroxidation only in the abdomen (30%) where lev els of antioxidant enzymes and especially luciferase are low. In contr ast, exposure to hypoxia (2% O-2) led to significant increases in prot horax citrate synthase (85%), succinate dehydrogenase (25%), and lacta te dehydrogenase (30%) activities, but not in luciferase or antioxidan t enzyme levels. LME administration alone decreased luciferase activit ies 20% but did not alter prothorax SOD activity. Prothorax SOD activi ty was increased by concomitant LME and hyperoxia treatments (30%), al ong with higher levels of TEARS (25%) and protein reactive carbonyl gr oups (50%). Altogether these data suggest that in elaterids, biolumine scence and reactions catalyzed by antioxidant enzymes may cooperate to minimize oxidative stress. (C) 1998 Elsevier Science Inc.