Biochemical warfare on the reef : the role of glutathione transferases in consumer tolerance of dietary prostaglandins

© 2010 The Authors. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS ONE 5 (2010): e8537, doi:10.1371/journal.pone.0008537.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 S-transferases (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 semi-purified 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. 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. 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 GSTs may 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.Financial support for this work was provided by the Ocean Life Institute Tropical Research Initiative Grant (WHOI) to KEW and MEH; the Robert H. Cole Endowed Ocean Ventures Fund (WHOI) to KEW; the National Undersea Research Center - Program Development Proposal (CMRC-03PRMN0103A) to KEW; Walter A. and Hope Noyes Smith, and a National Science Foundation Graduate Research Fellowship to KEW

Accumulation dynamics of PCBs in selected organs and tissues of carp (Cyprinus carpio L.)

The study was aimed at the PCB (Clophen A50) accumulation dynamics in the gill filaments, muscle tissue, perintestinal adipose tissue, alimentary tract and the liver of cultured carp, Cyprinus carpio L. when taken, only, either from contaminated water or contaminated diet. The highest accumulation dynamics was observed in first 5-10 days of intoxication followed by a visible decrease resulted partly from increase in a growth rate of the tested organs and tissues as well as from the smaller daily intake per weight unit of the tested fish

Dynamics of the PCBs decline in selected organs of carp (Cyprinus carpio L.) during depuration in clean water

The aim of this study was to determine the dynamics of PCB content decline in three selected organs and tissues (gill filaments, muscle tissue, perintestinal adipose tissue, liver, and alimentary tract) of cultured carp, previously exposed to Clophen A50 via oral route, in the course of their 40-day stay in PCB-free environment. The samples were analysed using gas chromatography. The highest decrease in PCB concentration, related to wet weight was noted for the perintestinal adipose tissue and the alimentary tract. The lowest PCB decrease in lipids was recorded in the liver (l0.0 %) and the highest one-in the alimentary tract. In decrease related to the total weight of the organs and tissue studied was the highest for the gill filaments (61.6 %) while the values compared for perintestinal adipose tissues showed a 6.6 % increase

Accumulation dynamics of PCBs in selected organs and tissues of carp (Cyprinus carpio L.)

The study was aimed at the PCB (Clophen A50) accumulation dynamics in the gill filaments, muscle tissue, perintestinal adipose tissue, alimentary tract and the liver of cultured carp, Cyprinus carpio L. when taken, only, either from contaminated water or contaminated diet. The highest accumulation dynamics was observed in first 5-10 days of intoxication followed by a visible decrease resulted partly from increase in a growth rate of the tested organs and tissues as well as from the smaller daily intake per weight unit of the tested fish

Polychlorinated hydrocarbons in fishes, blue mussel (Mytilus edulis) and bottom sediments of the south-western Baltic Sea

Polychlorinated hydrocarbons are convenient indicators of environmental pollution. The aim of this study was to determine the presence of p,p′-DDT and its metabolites (p,p′-DDE and p,p′-DDD) and γ-HCH and PCBs in: the dorsal muscles of 3 most important fish species (cod, herring, and flounder), in blue mussel, and in the bottom sediments off the coast of the south-western Baltic Sea. The analyses were carried out using the method of gas chromatography. The presence of all analysed compounds was detected in the samples studied. The highest concentrations of polychlorinated hydrocarbons in the bottom sediments were stated at the coast of Kiel, while the lowest-in the Świnoujście area. In blue mussels no such significant differences in the content levels of the analysed compounds were observed. The muscles of herring demonstrated the highest content of ΣDDT and PCBs. The present results will constitute a contribution to the knowledge on the presence of polychlorinated hydrocarbons in the marine environment of the south-western Baltic Sea

Changes in total PCB content in selected fish products during hot- and cold smoking

Background. Stability and high bioaccumulation coefficients of polychlorinated biphenyls (PCB) in aqueous organisms may constitute a health hazard for their consumers (it is really the potential toxicity of PCBs that determine their hazard—not stability). As the fish are mostly eaten in the form of processed products, the influence of technological processes and different methods of cooking on changes in the levels of toxic compounds in final products is of great importance and may be helpful for appropriate processing. Since smoked fish products are in great demand in Poland, the goal of this study was to determine changes in total PCB content in herring fillets during hot smoking and in hot and cold smoked mackerel fillets. Materials and methods. Herring fillets were hot smoked under industrial conditions, whereas mackerel fillets were cold- and hot smoked. Analyses were carried out using a capillary gas chromatograph coupled with a mass spectrometer GC-MS (HP 6890/5973) with a HP-5 column. Results. The hot smoking process affected the loss of total PCB content in mackerel and herring fillets, with its highest value in the first hour of partial drying. The main factor determining the changes in the content of these compounds in wet matter and lipids was their escape in co-distillation with water vapour. The increase of their content, in the final stage of hot smoking and during the whole cold smoking process, was caused by contamination of fish fillets with polychlorinated biphenyls present in the curing smoke. Conclusion. From the toxicological point of view the process of hot smoking, is much healthier for people because it causes the reduction of total PCB content in final smoked products. Cold smoked mackerel is much more popular on the Polish market for its stronger taste and aromatic smell. However, lengthy exposure to smoke in low temperature increased the total PCB content in cold smoked fish. The consumption of these products should be limited based on these results

Absorption of polychlorinated biphenyls (PCB) through gills and skin of common carp, Cyprinus carpio L

Gills and skin of mirror carp were exposed separately to Clophen A-50 in the concentration of 200 µg/dm3. After one hour, the content of polychlorinated biphenyls (PCB) was determined in the wet weight of the blood, muscles, and the skin as well as in the lipids of these tissues. It turned out that 63% ofthe PCB were absorbed through the gills, while only 32% - through the skin