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, gibbosum collected from P americana (21.4 to 27.4 pm01 mg-'1. A peak at ca 420 nm was also detected in most samples, indicative of degraded P450 or an independent, functional haemoprotein Methoxyresorufin 0-deethylase (MROD) and ethoxyresorufin 0-deethylase (EROD) were not detected in C. gibbosum. However, NADPH-cytochrome c (P4501 reductase (NCR) was detected in all samples and the specific activity ranged from 23.2 to 67.3 nmol min-' mg-' 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 pm01 min-' mg-l, ranking it among the highest ever reported (using l-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 actlvity varies in response to different suites of gorgonian allelochemicals.

Di-ortho polychlorinated biphenyls (PCBs) are prominent environmental contaminants and their biological activity in fish may be more significant than previously thought. Four weeks after intraperitoneal (i.p.) injection with 50 or 250 microg 2,2',4,4',5,5'-hexachlorobiphenyl (2HxCB)/g fish, rainbow trout livers were removed and frozen at -80 degrees C or microsomes were prepared. Microsomal ethoxyresorufin O-deethylase (EROD) activity was approximately one and two orders of magnitude greater than controls in fish treated with 50 and 250 microg 2HxCB/g fish, respectively. Cytochrome P4501A (CYP1A) Western immunoblot relative optical density increased with 2HxCB dose. Hepatic CYP1A1 mRNA levels were approximately threefold greater in fish treated with 250 microg 2HxCB/g fish than in controls, while hepatic CYP1A1 mRNA levels in fish treated with 50 microg 2HxCB/g fish were not significantly induced. There was no increase of CYP1A3 mRNA in 2HxCB-treated fish. The study showed 2HxCB induced hepatic EROD activity, CYP1A protein, and CYP1A1 mRNA content in rainbow trout.