Identification of biological threat agents in the environment and its challenge

The present invention relates to a method for quantitatively assaying the presence of DSP toxins such as okadaic acid and dinophysistoxin-1 in marine samples. The method comprises the steps of preparing a marine extract, fractionating the prepared marine extract and selecting the extract fraction containing the toxin to be assayed. Once the desired extract fraction has been selected, a labelled substrate for protein phosphatase and at least one protein phosphatase are added to the extract in an assay. The amount of toxin present is quantitatively measured by the ability of the extract fraction to inhibit catalysis, mainly dephosphorylation, of the labelled substrate by protein phosphatases, such as phosphatase-1 (PP1) or phosphatase-2A (PP2A). Preferably, the method of the present invention is used to assay the presence of okadaic acid in marine organisms such as mussels, oysters, scallops, phytoplankton and the like.