Functional characterization and expression of molluscan detoxification enzymes and transporters involved in dietary allelochemical resistance
Whalen, Kristen E.
MetadataShow full item record
Understanding how organisms deal with potentially toxic or fitness-reducing allelochemicals is important for understanding patterns of predation and herbivory in the marine environment. The ability of marine consumers to tolerate dietary toxins may involve biochemical resistance mechanisms, which increase the hydrophilicity of compounds and facilitate their active efflux out of sensitive cells and tissues. While several allelochemical-responsive detoxification enzymes have been sequenced and functionally characterized in terrestrial invertebrates feeding on chemically defended host plants, there is virtually no information concerning the role of these biotransformation enzymes that may mediate feeding tolerance in marine invertebrates. The objective of this research was to assess the diversity and dietary regulation of cytochrome P450s (CYP), glutathione S-transferases (GST) and ABC transporters in the generalist marine gastropod Cyphoma gibbosum feeding on a variety of chemically defended gorgonian corals, and to identify those dietary natural products that act as substrates for these proteins. Molecular and proteomic techniques identified both allelochemically-responsive CYPs, and constitutively expressed GSTs and transporters in Cyphoma digestive glands. Inhibition of Cyphoma GST activity by gorgonian extracts and selected allelochemicals (i.e., prostaglandins) indicated that gorgonian diets are likely to contain substrates for molluscan detoxification enzymes. In vitro metabolism studies with 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. Finally, the presence and activity of multixenobiotic resistance transporters in Cyphoma and the co-occuring specialist nudibranch, Tritonia hamnerorum, suggests these efflux transporters could function as a first line of defense against dietary intoxication. Together, these results suggest marine consumers that regularly exploit allelochemical-rich prey have evolved both general (GST and ABC transporters) and allelochemical-specific (CYP) detoxification mechanisms to tolerate prey chemical defenses.
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2008
Showing items related by title, author, creator and subject.
Walsh, David (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1992-04)A pair of simple models representing the interaction of a continuously stratified f-plane quasigeostrophic lens with a uniform external shear flow is examined. The study is motivated by the desire to understand the ...
Bunker, Andrew F.; Haurwitz, B.; Malkus, Joanne Starr; Stommel, Henry M. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1949)The observations presented and discussed in this paper were obtained as part of a research project conducted under contract NObs-2083 with the Bureau of Ships of the U. S. Navy by the Woods Hole Oceanographic Institution. ...
Involvement of Cytochrome P450 1A in the toxicity of aryl hydrocarbon receptor agonists : alteration arachidonic acid metabolism and production of reactive oxygen species Schlezinger, Jennifer J. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1998-08)Two cytochrome P4501A-dependent mechanisms of aryl hydrocarbon receptor (AhR) agonist toxicity were examined in the marine teleost scup (Stenotomus chrysops), alteration of arachidonic acid (AA) metabolism and production ...