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, 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.

Chemical mediation of interactions among marine organisms

“…2 Recently, Thorton and Kerr 288 reported that high levels of predation by the mollusc Cyphoma gibbosum induced pseudopterosin C 81 production by Pseudopterogorgia elisabethae. While some experimental evidence suggests that C. gibbosum may use biotransformation enzymes to detoxify gorgonian metabolites, 262 this is the first instance where a specialist has been shown to induce the production of a gorgonian metabolite. Interestingly, induction did not occur after high levels of predation by the butterfly fish Chaetodon capistratus or artificial wounding of the sea fan.…”

Proteomic identification, cDNA cloning and enzymatic activity of glutathione S-transferases from the generalist marine gastropod, Cyphoma gibbosum

“…The high concentration of allelochemicals in gorgonian corals [27,[37][38][39][40], coupled with the findings that digestive glands of C. gibbosum contain high levels of GST activity [9], prompted an investigation to identify and biochemically characterize those GST enzymes possibly responsible for detoxifying gorgonian allelochemicals.…”

“…Enzyme activity was measured using CDNB as a substrate by the method of [32] optimized for C. gibbosum [9] …”

“…Only a few studies have addressed the induction of GSTs upon exposure to allelochemicals in marine invertebrates [7][8][9]. One such study [9] examined GST activity in the digestive gland of a generalist gastropod, Cyphoma gibbosum, which exclusively feeds on several families of chemically defended gorgonian corals.…”

“…One such study [9] examined GST activity in the digestive gland of a generalist gastropod, Cyphoma gibbosum, which exclusively feeds on several families of chemically defended gorgonian corals. The authors reported significantly higher GST activity in field-collected C. gibbosum feeding on gorgonians Gorgonia ventalina and Briareum asbestinum, suggesting that GST expression varies in response to different suites of gorgonian allelochemicals.…”