Lipophilic toxicity from the marine dinoflagellate Karenia brevisulcata: use of the brevetoxin neuroblastoma assay to assess toxin presence and concentration.

A method for assessing the presence and concentration of a major toxin produced by Karenia brevisulcata has been developed, based on the neuroblastoma assay for brevetoxins. This cytotoxicity assay, coupled with observations of the dose-response relationship and of changes in cellular morphology during the assay gave a characteristic toxin 'signature'. This signature was consistent whether the toxicity was assessed in extracts of shellfish, seawater samples, uni-algal cultures of K. brevisulcata, or in partially purified toxin samples. Using this method it was possible to confirm the presence of this toxicity during a mixed Karenia bloom, and infer that K. brevisulcata toxin (KBT) was the probable cause of the fish and shellfish mortality observed at that time. The neuroblastoma assay thus provides a solution to the problem of confirming the presence of KBT in suspected K. brevisulcata events, even in the absence of a known toxin structure.