COELENTERAZINE DISTRIBUTION AND LUCIFERASE CHARACTERISTICS IN OCEANICDECAPOD CRUSTACEANS

Coelenterazine biosynthesis has recently been demonstrated in the deve loping eggs of the decapod Systellaspis debilis. The cellular source o f coelenterazine and the potential for biosynthesis in adult decapods, however, have not been fully investigated. We have conducted a system atic study of coelenterazine content in > 230 individual decapods repr esenting 19 species of Oplophoridae and 22. species from other familie s. We show for the first time that coelenterazine is responsible for b oth secretory and photophore luminescence in the same decapod. Tissues associated with secretory luminescence (hepatopancreas and stomach) i n the Oplophoridae contained almost 3 orders of magnitude more coelent erazine (mean value = 2154 pmol per specimen) than cuticular photophor es (mean value = 8 pmol per specimen). Coelenterazine content increase s by 2 to 4 orders of magnitude during the development of three specie s of Oplophoridae. Species of Oplophoridae contain an order of magnitu de more coelenterazine than those of other families (mean value = 154 pmol per specimen). Coelenterazine was also detected in 11 apparently nonluminous decapod species (mean value = 200 pmol per specimen). S. d ebilis luciferase characterisation enabled a luciferase assay to be de veloped to facilitate studies of the environmental control of biolumin escence. We hypothesise that the coelenterazine requirement in secreto ry bioluminescence exceeds that which could be assimilated from the fo od-chain. The significant increase of coelenterazine during the life c ycle of secretory decapods supports this hypothesis. Putative evidence for environmental control of coelenterazine luminescence is also repo rted.