DNA probes for ASP producers
Amnesic shellfish poisoning, or ASP, is caused by micro-algae in the diatom genus Pseudo-nitzschia. Some Pseudo-nitzschia species are highly toxic, some mildly toxic, and others are non-toxic. Up till now several days of cell preparation followed by high-powered electron microscopy has been required for confident identifications. Now, with DNA probes developed by Dr Chris Scholin, Monterey Bay Aquarium Research Institute (MBARI), in California, the species can be determined in 4 hours from receipt of a seawater sample.

Probes for PSP producers

Paralytic shellfish poison (PSP) causes paralysis in extreme cases and is of concern world-wide. DNA probes, targeted at rRNA, have been developed by Chris Scholin for the dinoflagellate genus Alexandrium, and for some Alexandrium species. The whole cell format probes are now available for commercial testing and sandwich hybridisation assays are also available.

Probes for NSP producers

Whole cell probes for the range of brevetoxin producers are currently being designed and trialled. Probes for all the Karenia species have been designed and validated in the whole cell format. SHA format probes are also being developed.

Probes for fish killers too....
Several micro-algal species can kill fish. John Tyrrell, working at Auckland University and then at MBARI with Chris Scholin, has developed sandwich hybridisation assay probes for Heterosigma akashiwo, Fibrocapsa japonica and Chattonella antiqua. Cawthron has international accreditation for the use of these probes (IANZ).

Recently probes for Karlodinium micrum and Takayama tasmanica and T.helix were designed by Miguel de Salas, University of Tasmania, and trialled at Cawthron in Nelson, New Zealand.

DNA probes will soon be available for all toxic micro-algae, and different marine farms will be able to select "designer" sets of probes specifically suited to their needs. It is likely that probes will be developed for a range of other purposes in the marine environment, from disease detection to rapid recognition of unwanted "invaders".

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