Monitoring of brevetoxins in the Karenia brevis bloom-exposed Eastern oyster (Crassostrea virginica)

Gulf Coast Seafood Laboratory, U.S. Food and Drug Administration, 1 Iberville Drive, Dauphin Island, AL 36528, USA.
Toxicon (Impact Factor: 2.49). 05/2008; 52(1):32-8. DOI: 10.1016/j.toxicon.2008.04.174
Source: PubMed


Brevetoxin uptake and elimination were examined in Eastern oyster (Crassostrea virginica) exposed to recurring blooms of the marine alga Karenia brevis in Sarasota Bay, FL, over a three-year period. Brevetoxins were monitored by in vitro assays (ELISA, cytotoxicity assay, and receptor binding assay) and LC-MS, with in vivo toxicity of shellfish extracts assessed by the traditional mouse bioassay. Measurements by all methods reflected well the progression and magnitude of the blooms. Highest levels recorded by mouse bioassay at bloom peak were 157 MU/100g. Oysters were toxic by mouse bioassay at levels >or=20 MU/100g for up to two weeks after bloom dissipation, whereas brevetoxins were measurable by in vitro assays and LC-MS for several months afterwards. For the structure-based methods, summed values for the principal brevetoxin metabolites of PbTx-2 (cysteine and cysteine sulfoxide conjugates), as determined by LC-MS, were highly correlated (r(2)=0.90) with composite toxin measurements by ELISA. ELISA and LC-MS values also correlated well (r(2)=0.74 and 0.73, respectively) with those of mouse bioassay. Pharmacology-based cytotoxicity and receptor binding assays did not correlate as well (r(2)=0.65), and were weakly correlated with mouse bioassay (r(2)=0.48 and 0.50, respectively). ELISA and LC-MS methods offer rapid screening and confirmation, respectively, of brevetoxin contamination in the oyster, and are excellent alternatives to mouse bioassay for assessing oyster toxicity following K. brevis blooms.

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    • ") of 0.5 and 0.6 (Fig. 7), respectively; in the Eastern oyster, correlation coefficient values of 0.7 were reported (Plakas et al., 2008). The mild conditions used for LC-MS and ELISA extract preparation is expected to preserve the structural integrity of brevetoxins as present in clams and the results reflective of the major metabolites. "
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    ABSTRACT: Brevetoxins in clams (Mercenaria sp.) exposed to recurring blooms of Karenia brevis in Sarasota Bay, FL, were studied over a three-year period. Brevetoxin profiles in toxic clams were generated by ELISA and LC-MS. Several brevetoxin metabolites, as identified by LC-MS, were major contributors to the composite brevetoxin response of ELISA. These were S-desoxyBTX-B2 (m/z 1018), BTX-B2 (m/z 1034), BTX-B5 (m/z 911), open A-ring BTX-B5 (m/z 929), and BTX-B1 (m/z 1018). Summed values of these metabolites were highly correlated (R2 = 0.9) with composite B-type brevetoxin measurements by ELISA. S-desoxyBTX-B2, BTX-B2, and BTX-B1 were the most persistent and detectable in shellfish for several months after dissipation of blooms. These metabolites were selected as LC-MS biomarkers of brevetoxin exposure and reflective of composite B-type brevetoxins in hard clam. ELISA and LC-MS values were moderately correlated with toxicity of the shellfish by mouse bioassay. ELISA and LC-MS methods offer rapid screening and confirmatory determination of brevetoxins, respectively, as well as toxicity assessment in clams exposed to K. brevis blooms.
    Toxicon 01/2015; 96(1). DOI:10.1016/j.toxicon.2015.01.014 · 2.49 Impact Factor
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    • "This functional role in the food web may play a critical role in toxin transfer to higher trophic levels. While numerous studies have been conducted on brevetoxin accumulation by commercially exploited suspension-feeding bivalves (e.g., Roberts et al., 1979; Plakas et al., 2008), there is limited information on brevetoxin accumulation in the natural benthic community during a harmful algal bloom (Simon and Dauer, 1972; Summerson and Peterson, 1990; Pierce et al., 2004a). The objective of this study was therefore to investigate toxin trophic transfer from toxic algae to a macrobenthic community from nearshore Florida waters. "
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    ABSTRACT: Harmful algal blooms can cause mass mortalities of top predators such as fish, marine mammals and seabirds but the food web transfer from toxic phytoplankton to these organisms has not been fully elucidated. Macrobenthic invertebrates in coastal waters, including bivalve suspension- and deposit-feeders, carnivorous gastropods, deposit-feeding amphipods and polychaetes, are a major food source for a wide variety of predators and can thus play a critical role in the trophic transfer of algal toxins to higher trophic levels. The objective of this study was to investigate toxin accumulation in transplanted juvenile hard clams, Mercenaria mercenaria, a species naturally occurring in the region, and in various macrobenthic functional groups from Florida coastal waters during a natural bloom of the dinoflagellate, Karenia brevis, a producer of brevetoxins. Bloom concentrations in the water column ranged from 100 to 1200 cells ml−1 over the course of the experiment. This study revealed that these lipophilic toxins can be rapidly accumulated by both suspension- and deposit-feeding benthos, especially bivalve molluscs [1.9–2.8 μg PbTx-3 eq (g wet weight)−1]. Transplanted M. mercenaria rapidly accumulated toxins from the water column attaining ∼0.5 μg PbTx-3 eq (g wet tissue)−1 after only 4 h-exposure to the K. brevis bloom and a maximum value of 1.5 ± 0.2 μg PbTx-3 eq (g wet tissue)−1 after 72 h. Relatively high brevetoxin concentrations were also measured in co-occurring benthic carnivorous gastropods [1–2.6 μg PbTx-3 eq (g wet weight, WW)−1]. Mean toxin concentrations in polychaetes and crustaceans varied in the range ∼0.04–0.2 μg PbTx-3 eq (g WW)−1 over the study period, and thus were typically lower than in molluscs. This study demonstrated in situ toxin accumulation by benthic primary and secondary consumers during a natural Florida red tide. Accumulation by primary consumers may be highly variable in space and time (as shown in bivalves from the natural benthic community) and among taxonomic groups. Toxin transfer further up the food web will thus depend on the toxin level accumulated in prey, the number of pathways from which the predator may accumulate toxins and on possible biological magnification of lipophilic toxins. Overall, this study revealed qualitatively and quantitatively that benthic consumers of a number of taxa can serve as vectors for transporting brevetoxins within the food web.
    Harmful Algae 04/2012; 16:27–34. DOI:10.1016/j.hal.2012.01.001 · 3.87 Impact Factor
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    • "The elutant from LC was analyzed by an Applied Biosystems/MDS Sciex 4000 QTRAP hybrid triple quadrupole/linear ion trap mass spectrometer equipped with a Turbo V™ source (Applied Biosystems, Foster City, CA, USA). The detection of brevetoxin congeners and metabolites by mass spectrometry was achieved by multiple reaction monitoring (MRM) and selected ion monitoring (SIM) [53], [54]. The following brevetoxin congeners and their derivatives were analyzed by comparison to commercial and/or in house derivatized standards: brevetoxin-1, -2, -3, -7, -9, oxidized brevetoxin-2, open A-ring brevetoxin-2, -3, -7, oxidized brevetoxin-2, cysteine-brevetoxin-A(B) and its sulfoxide, open-A ring cysteine-brevetoxin-B, and glutathione-brevetoxin-A(B). "
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    ABSTRACT: Sentinel species such as bottlenose dolphins (Tursiops truncatus) can be impacted by large-scale mortality events due to exposure to marine algal toxins. In the Sarasota Bay region (Gulf of Mexico, Florida, USA), the bottlenose dolphin population is frequently exposed to harmful algal blooms (HABs) of Karenia brevis and the neurotoxic brevetoxins (PbTx; BTX) produced by this dinoflagellate. Live dolphins sampled during capture-release health assessments performed in this region tested positive for two HAB toxins; brevetoxin and domoic acid (DA). Over a ten-year study period (2000-2009) we have determined that bottlenose dolphins are exposed to brevetoxin and/or DA on a nearly annual basis (i.e., DA: 2004, 2005, 2006, 2008, 2009; brevetoxin: 2000, 2004, 2005, 2008, 2009) with 36% of all animals testing positive for brevetoxin (n = 118) and 53% positive for DA (n = 83) with several individuals (14%) testing positive for both neurotoxins in at least one tissue/fluid. To date there have been no previously published reports of DA in southwestern Florida marine mammals, however the May 2008 health assessment coincided with a Pseudo-nitzschia pseudodelicatissima bloom that was the likely source of DA observed in seawater and live dolphin samples. Concurrently, both DA and brevetoxin were observed in common prey fish. Although no Pseudo-nitzschia bloom was identified the following year, DA was identified in seawater, fish, sediment, snails, and dolphins. DA concentrations in feces were positively correlated with hematologic parameters including an increase in total white blood cell (p = 0.001) and eosinophil (p<0.001) counts. Our findings demonstrate that dolphins within Sarasota Bay are commonly exposed to two algal toxins, and provide the impetus to further explore the potential long-term impacts on bottlenose dolphin health.
    PLoS ONE 03/2011; 6(3):e17394. DOI:10.1371/journal.pone.0017394 · 3.23 Impact Factor
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