Presence of coelenterazine in mesopelagic fishes from the Strait of Messina

Coelenterazine, a luciferine, and luciferase activity specific to coelenterazine were detected and assayed in various tissues of mid-water fishes, Argyropelecus hemigymnus, Chauliodus sloani, Myctophum punctatum, Vinciguerria attenuata and Cyclothone braueri. Coelenterazine was found mainly in digestive systems and photophores of these fishes. A large species to species variation was found: extremely high levels of coelenterazine and luciferase were found in the M. punctatum digestive system whereas only a very low level of coelenterazine was detected in C. braueri. Coelenterazine was detected in A. hemigymnus eggs supporting the hypothesis of a maternal transfer of luminous capabilities. Luciferase activity specific to coelenterazine was found in photophores as well as in various other tissues suggesting another (besides light emission) biological function for this enzymatic activity. Distribution of coelenterazine in all tissues of the individuals supports the hypothesis of the dietary acquisition of coelenterazine by these fishes.