Study on DNA probe speciric for toxic dinoflagellate

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Toxic dinoflagellates Alexandrium catenella and A.tamarense produce potent neurotoxins responsible for paralytic shellfish poisoning (PSP) in coastal waters and cause serious economic and public health problems. However, the morphological taxonomy of these organisms remains controversial because of the very similar and changeable features. Accordingly, a simple and objective method for identification is a pressing need. In this study I attempted to identify these species by rDNA sequence and to develop DNA probe specific for each species. The results are as follows ;(1) PSP toxins from many strains of A.tamarense and A.catenella were analyzed by HPLC-fluorometric analysis and the typical strains showing different toxin content and composition were selected for following studies.(2) The 5.8SrDNA and flanking internal transcribed spacer (ITS1 and ITS2) from these strains were amplified using the PCR and subjected to restriction fragment-length polymorphism (RFLP) analysis. RFLP analysis of this region is useful for species discrimination.(3) It was possible to discriminate both toxic species from non toxic ones by phylogenetic analysis using DNA sequence comparison of the 5.8SrDNA and ITS regions.(4) The 3' end of ITS1 region (149-177bp) is definitely an effective DNA probe for the identification of toxic Alexandrium species.