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 O2 detoxifying mechanism. The activities of antioxidant enzymes and of luciferase in the prothorax (bright) and abdomen (dim) of luminous larval Pyrearinus termitilluminans (Coleoptera: Elateridae) were measured after previous challenge with either hyperoxia, hypoxia, or the firefly luciferase inhibitor luciferin 6'-methyl ether (LME). Upon exposure to pure O2 for 72 h, the prothorax activities of total superoxide dismutase (SOD) and catalase were found to increase by 85% and 50%, respectively. Concomitantly, levels of luciferase and luciferin increased 80% and 50%. Assays of thiobarbituric acid reactive substances (TBARS) showed significantly augmented lipid peroxidation only in the abdomen (30%) where levels of antioxidant enzymes and especially luciferase are low. In contrast, exposure to hypoxia (2% O2) led to significant increases in prothorax citrate synthase (85%), succinate dehydrogenase (25%), and lactate dehydrogenase (30%) activities, but not in luciferase or antioxidant enzyme levels. LME administration alone decreased luciferase activities 20% but did not alter prothorax SOD activity. Prothorax SOD activity was increased by concomitant LME and hyperoxia treatments (30%), along with higher levels of TBARS (25%) and protein reactive carbonyl groups (50%). Altogether these data suggest that in elaterids, bioluminescence and reactions catalyzed by antioxidant enzymes may cooperate to minimize oxidative stress.

A comparison of the effect of experimental general anaesthetics on nerve impulse blockade and on a proteinaceous target site.

While it has been reported that general anaesthetics inhibit the enzyme luciferase and thus reduce the light output of the reaction with luciferin, we find that in squid giant axons injected with luciferin and luciferase, treatment with experimental general anaesthetics at concentrations sufficient to block axonal conduction leads to an increase in the light production by the reaction. This potentiation of the protein activity is best observed when luciferin concentration is above the apparent association constant. Our findings raise doubts regarding the suitability of luciferase as a model for the target region of general anesthetic action.