Development and Utilization of Biosenser by Means of Genetic Marker of Harmful and Noxious Microalgae

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Harmful and noxious microalgae in costal weaters and cause serious problems in publich health and fisheries. The morphological taxonomy of these microalgae, however, remains controversial because of the similarity and changeability of morphological features. Accordingly, a objective and precise method for identification is really reqiured. In this study we established the base of monitoring of these noxious species by flow cytometry using a monoclonal antibody and DNA probes. The results obtained are as follows ;# We enumerated the microorganisms which killed the noxious red tide phytoplankton Heterosigma akashiwo (raphidophyceae) and Gymnodinium mikimotoi, (dinophyceae) haduring their blooms which occurred in Hiroshima Bay and Uranouchi Bay or Tanabe Bay, Osaka Bay'Japan, in 1995,1996 and 1997 using the MPN method. At every sampling site in these years, the rapid increase of the algicidal microorganisms in the seawater fractions less than 0.8mum was observed at the termination period of the blooms.# We cloned and sequenced 5.8SrDNA and ITS1 / ITS2 regions of several strains of Alexandrium spp. In this experiments we it became clear that the nucleotide sequences of 3'-region of ITS1 were similar in the intratypes but not in entertypes. So, it is possible to discriminate Alexandrium tamarense and A.catenella by means of PCR methods with specific primers.# The nucleotides sequence of 18SrDNA of G.mikimotoi had 97% abd 94% similarity against Prorocentrum micans and Symbiodinium sp., respectively.# We developed a new DNA probe which is very specific for G.mikimotoi.# The G.mikimotoi cells labeled with the specific DNA brobe were easily discriminate from other microalgae by means of flowcytomete.