12th International Conference on Harmful Algae

INTERNATIONAL SOCIETY FOR THE STUDY OF HARMFUL ALGAE12 th <strong>International</strong> <strong>Conference</strong> on Harmful Algae, Copenhagen, Denmark, 4-8 September 2006bloom levels. High levels of algaldensity (up to 28.9 millionflagellates/l, 31.6 millionpicoplankters/l and 8.9 million otheralgal cells/l) were attained.Phytoplankton biomass measuredin terms of chlorophyll alsoresponded similarly. From thisstudy, it is evident that enrichmentwith sewage could inducedevelopment of algal blooms inmicrocosms. The magnitude of theblooms and their productioncharacteristics were high. Thepresence of a variety ofphytoplankton species in bloomdensities, particularly thedinoflagellates implicated intoxigenic episodes elsewhere, is amatter of concern anddemonstrated the existence of apotential for development oftoxigenic algal blooms off this coastdue to eutrophication.PO.08-01Verification of diarrhetic activitiesof PTX-2 and okadaic acid in vivoSession: PO.08 - ToxicologyEmiko ItoChiba University, CHIBA, JapanDiarrhetic activities of OA and PTX-2 were studied in mouse and rat byoral route.Stock solutions of OA and PTX2were prepared with 50 % ethanoland dimethylformamide and dilutedwith saline before use. At sublethaldoses, both toxins produced in micethe severest tissue injuries in thesmall intestine at 60 min and themaximum fluid accumulation at 90min. The recovery thereafter waswell and rapid. The minimumadverse effect doses for OA andPTX2 were estimated to be 75μg/kg and 400 μg/kg, respectively.Single administration of OA at 50μg/kg or PTX2 at 300 μg/kg did notcause fluid accumulation, however,by co-administration they hadsynergistic effect. The effects of thetwo toxins were discernible. TheOA-induced erosion wascharacterized by edema, whilevacuole formation at epithelial cellswas more prominent with PTX2. Incontrast to mice, rats were moretolerant to the toxins. Both OA andPTX2 diluted in saline causedintestinal fluid accumulation at 400μg/kg and over. Use of triolein-oil forOA dilution lowered the minimumeffective dose to 200 μg/kg and theuse of 2% lecithin-water lowered theminimum effective dose for PTX2 to300 μg/kg.PO.01-23Phylogenetic relationshipsbetween Cochlodiniumpolykrikoides populations fromJapanese and East Asian coastsSession: PO.01 - GeneticsMitsunori Iwataki 1 , Hisae Kawami 1 ,Kazumi Matsuoka 1 , Y Fukuyo 21 Nagasaki University, NAGASAKI, Japan2 Tokyo University, TOKYO; JapanThe unarmoured dinoflagellateCochlodinium polykrikoides isresponsible for recurrent massmortalities of fish in East andSoutheast Asian countries. InJapanese and Korean coastalwaters, blooms of this species occurevery summer. To distinguish thepopulations and their geographicaldistribution, SSU rDNA and partialLSU rDNA sequences of C.polykrikoides collected along thecoasts of Western Japan wereanalyzed and compared tosequences from Korea, Philippinesand Malaysia. In the phylogenetictree constructed by the gammaweighted neighbour-joining method,198