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 2006had become very heterogeneous interms of toxicity and mitochondrialgenotypes; and the stability of them,although the OF935-AT6 wasestablished from one single cellfrom natural population.PO.02-08Mononucleotide polymorphism ofa microcystin synthetase, mcyHin the releasing of microcystinsin a specific strain of MicrocystisaeruginosaSession: PO.02 - GenomicsHN ChouNational Taiwan University, TAIPEI, TaiwanMicrocystins are a group ofhepatotoxins produced mainly bytoxic species of Microcystis throughthe function of microcystinsynthetases that are coded from aseries of genes, mcyA~mcyJ. Thetoxins are produced within thecyanobacteria cells and areexpected to be predominantly foundin slow-growing, healthy cells.Microcystin release is generallyconsidered to be linked to adecrease in the integrity of the cells.However, in a strain of M.aeruginosa it was foundmicrocystins are released during thelog phase of growth andcontinuously accumulate in the cellfreemedium. A single nucleotidedifference of the sequence mcyHwas found in the toxin-releasingstrain compared to other non-toxinreleasing strains. The sequence ofmcyH is known to be homologous tothe bacteria transporter, but is alsoknown as a key protein thatmaintains the integrity of themicrocystin synthetase clusters.PO.08-02Biologically active substanceswith spiro-linked rings in seafoodSession: PO.08 - ToxicologyB Christian 1 , B Luckas 1 , G Gerdts 21 Institute of Nutrition, JENA, Germany2 Alfred-Wegener-Institute, HELGOLAND,GermanyIn the middle of the 1990s a newclass of neurotoxins was discoveredin aquaculture sites along the EastCoast of Canada. These toxinswere found to be 'fast acting' toxinscausing death within severalminutes when injected into mice.The molecular structure of thetoxins, named spirolides, consists ofa spiro-linked, tricyclic system ofpolyethers and a seven-memberedspiro-linked cyclic iminium moiety.Spirolides were first isolated fromshellfish and later from planktonsamples. In 2000, Alexandriumostenfeldii was identified as thecausative organism of spirolides.Whereas spirolides belonging togroups A-D are biologically active,spirolides E and F show nobiological activity. The instability ofthe cyclic iminium function underenzymatic or acid conditions can beimportant with respect to an oraltoxicity of spirolides.The Alfred-Wegener-Institute forPolar- and Marine Research (AWI)on Helgoland Island succeeded incultivating a Danish strain ofAlexandrium ostenfeldii (KO287).Subsequently the extracts weretested for spirolides by LC-MS/MS.For a study of the metabolisation ofspirolides in shellfish, extracts fromtissues of edible mussels wereincubated with an extractof KO287. The measurement ofextracts from mussels´ tissuesrevealed no characteristicdifferences in the spirolide profilecompared to KO287.151