Title:
Biochemical Warfare on the Reef: The Role of Glutathione Transferases in Consumer Tolerance of Dietary Prostaglandins
Biochemical Warfare on the Reef: The Role of Glutathione Transferases in Consumer Tolerance of Dietary Prostaglandins
Author(s)
Whalen, Kristen E.
Lane, Amy L.
Kubanek, Julia
Hahn, Mark E.
Lane, Amy L.
Kubanek, Julia
Hahn, Mark E.
Advisor(s)
Editor(s)
Collections
Supplementary to
Permanent Link
Abstract
Background: Despite the profound variation among marine consumers in tolerance for allelochemically-rich foods, few
studies have examined the biochemical adaptations underlying diet choice. Here we examine the role of glutathione Stransferases
(GSTs) in the detoxification of dietary allelochemicals in the digestive gland of the predatory gastropod
Cyphoma gibbosum, a generalist consumer of gorgonian corals. Controlled laboratory feeding experiments were used to
investigate the influence of gorgonian diet on Cyphoma GST activity and isoform expression. Gorgonian extracts and semipurified
fractions were also screened to identify inhibitors and possible substrates of Cyphoma GSTs. In addition, we
investigated the inhibitory properties of prostaglandins (PGs) structurally similar to antipredatory PGs found in high
concentrations in the Caribbean gorgonian Plexaura homomalla.
Principal Findings: Cyphoma GST subunit composition was invariant and activity was constitutively high regardless of
gorgonian diet. Bioassay-guided fractionation of gorgonian extracts revealed that moderately hydrophobic fractions from
all eight gorgonian species examined contained putative GST substrates/inhibitors. LC-MS and NMR spectral analysis of the
most inhibitory fraction from P. homomalla subsequently identified prostaglandin A2 (PGA2) as the dominant component. A
similar screening of commercially available prostaglandins in series A, E, and F revealed that those prostaglandins most
abundant in gorgonian tissues (e.g., PGA2) were also the most potent inhibitors. In vivo estimates of PGA2 concentration in
digestive gland tissues calculated from snail grazing rates revealed that Cyphoma GSTs would be saturated with respect to
PGA2 and operating at or near physiological capacity.
Significance: The high, constitutive activity of Cyphoma GSTs is likely necessitated by the ubiquitous presence of GST
substrates and/or inhibitors in this consumer’s gorgonian diet. This generalist’s GSTsmay operate as ‘all-purpose’ detoxification
enzymes, capable of conjugating or sequestering a broad range of lipophilic gorgonian compounds, thereby allowing this
predator to exploit a range of chemically-defended prey, resulting in a competitive dietary advantage for this species.
Sponsor
Date Issued
2010-01-06
Extent
Resource Type
Text
Resource Subtype
Article