Biotransformation enzymes in Cyphoma gibbosum (Gastropoda: Ovulidae)- implications for detoxification of gorgonian allelochemicals

Abstract

The role of biotransformation enzymes in metabolism of lipophilic, dietary allelochemicals such as terpenoids and steroids has not been studied in marine organisms despite the significance of allelochemicals in the evolution of biotransformation enzymes and the importance of these enzymes in detoxification of anthropogenic xenobiotics. Here we report on cytochrome P450 and glutathione transferase (GST) from the digestive gland of Cyphoma gibbosum, a specialist predator that feeds on allelochemically rich gorgonian corals. Levels of these enzymes were compared from C. gibbosum collected in Belize from 4 different gorgonian prey species (Briareum asbestinum, Gorgonia ventalina, Plexaura homomalla, and Pseudopterogorgia americana). Cytochrome P450 specific content was very low and only quantifiable in C. gibbosurn collected from P. americana (21.4 to 27.4 pmol mg-1). A peak at ca 420 nm was also detected in most samples, indicative of degraded P450 or an independent, functional haemoprotein. Methoxyresorufin O-deethylase (MROD) and ethoxyresorufin O-deethylase (EROD) were not detected in C. gibbosum. However, NADPH-cytochrome c (P450) reductase (NCR) was detected in all samples and the specific activity ranged from 23.2 to 67.3 nmol min-1 mg-1 protein. Significantly higher NCR activity was detected in C. gibbosum collected from prostaglandin-rich P. homomalla. Glutathione transferase specific activity ranged from 2.76 to 4.05 mumol min-1 mg-1, ranking it among the highest ever reported (using 1-chloro-2,4-dinitrobenzene as a model substrate), Significantly higher GST activity was detected in C. gibbosum collected from G. ventalina and B. asbestinum, suggesting that GST activity varies in response to different suites of gorgonian allelochemicals.