Functional Characterization and Expression of Molluscan Detoxification Enzymes and Transporters Involved in Dietary Allelochemical Resistance
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The processes underlying dietary allelochemical tolerance are likely mediated, in part, by biochemical resistance mechanisms that have evolved under the selective pressure of host chemical defenses. Although many have invoked this hypothesis to explain the variation in marine consumer tolerance, few studies have examined the enzymatic diversity and corresponding metabolism of dietary allelochemicals. Molecular and proteomic techniques identified both allelochemically-responsive cytochrome P450s CYPs, and constitutively expressed glutathione S-transferases GSTs and ABC transporters in Cyphoma gibbosum digestive glands. Inhibition of Cyphoma GST activity by gorgonian extracts and selected allelochemicals i.e., prostaglandins indicated that gorgonian diets contain substrates for molluscan detoxification enzymes. Enzymatic studies with snail microsomes and recombinant CYPs suggested those Cyphoma enzymes most closely related to vertebrate fatty acid hydroxylating enzymes may contribute to the detoxification of ichthyodeterrent cyclopentenone prostaglandins found in abundance in selected gorgonian species.