Brevetoxin metabolism and elimination in the Eastern oyster (Crassostrea virginica) after controlled exposures to Karenia brevis

Toxicon. 2004 Nov;44(6):677-85. doi: 10.1016/j.toxicon.2004.07.027.

Abstract

The metabolism and elimination of brevetoxins were examined in the Eastern oyster (Crassostrea virginica) following controlled exposures to Karenia brevis cultures in the laboratory. After a 2-day exposure period ( approximately 62 million cells/oyster), elimination of brevetoxins and their metabolites was monitored by using liquid chromatography/mass spectrometry (LC/MS). Composite toxin in oyster extracts was measured by in vitro assay (i.e. cytotoxicity, receptor binding, and ELISA). Of the parent algal toxins, PbTx-1 and PbTx-2 were not detectable by LC/MS in K. brevis-exposed oysters. PbTx-3 and PbTx-9, which are accumulated directly from K. brevis and through metabolic reduction of PbTx-2 in the oyster, were at levels initially (after exposure) of 0.74 and 0.49 microg equiv./g, respectively, and were eliminated largely within 2 weeks after dosing. PbTx-7 and PbTx-10, the reduced forms of PbTx-1, were non-detectable. Conjugative brevetoxin metabolites identified previously in field-exposed oysters were confirmed in the laboratory-exposed oysters. Cysteine conjugates of PbTx-1 and PbTx-2, and their sulfoxides, were in the highest abundance, as apparent in LC/MS ion traces, and were detectable for up to 6 months after dosing. Composite toxin measurements by in vitro assay also reflected persistence (up to 6 months) of brevetoxin residues in the oyster. Levels of cysteine conjugates, as determined by LC/MS, were well correlated with those of composite toxin, as measured by ELISA, throughout depuration. Composite toxin levels by cytotoxicity assay were well correlated with those by receptor binding assay. Cysteine-PbTx conjugates are useful LC/MS determinants of brevetoxin exposure and potential markers for composite toxin in the Eastern oyster.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Binding, Competitive / drug effects
  • Biological Assay
  • Chromatography, Liquid
  • DNA Adducts / chemistry
  • Dinoflagellida / chemistry*
  • Dose-Response Relationship, Drug
  • Enzyme-Linked Immunosorbent Assay
  • Marine Toxins / metabolism*
  • Marine Toxins / toxicity
  • Mass Spectrometry
  • Mice
  • Ostreidae / metabolism*
  • Oxocins / metabolism*
  • Oxocins / toxicity
  • Rats
  • Tritium

Substances

  • DNA Adducts
  • Marine Toxins
  • Oxocins
  • Tritium
  • brevetoxin T17
  • brevetoxin