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 2006activities, toxins produced by K.concordia and K. brevisulcata actedmuch faster than that of K.mikimotoi. Unlike K. mikimotoi, bothK. concordia and K. brevisulcata arelethal nearly to all organsims tested.The potential for using thebioassays developed as diagnostictests for the differenthaemolytic/neurotoxic toxins arediscussed.O.10-04Impact of environmental factorson growth, toxicity and toxinproduction of harmful algaeChattonella marina (Kagoshimastrain)Session: O.10 - Toxin analysis 2Presentation time: 15:55 - 16:15Shahroz M HaqueBagladesh Agricultural University,MYMENSINGH, BangladeshGrowth, toxin profile and intensity oftoxicity of the red tide-formingphytoflagellate Chattonella marina(Kagoshima Strain) wereinvestigated at differenttemperatures and light intensities.The optimal growth range was at25-30 °C and a light intensity of100-150 µmol m -2 s -1 .Ichthyotoxicities at differenttemperatures and light intensitieswere found to vary immensely, thehighest toxicity was found at 20 °Cand 150 µmol m -2 s -1 . Chattonellamarina contained the toxincomponents CmTx-I, CmTx-II,CmTx-III and CmTx-IV,corresponding to PbTx-2, PbTx-9,PbTx-3 and oxidized PbTx-2. Toxinyields varied markedly withtemperature and light intensity. Thetoxic components CmTx-I, CmTx-IIand CmTx-III peaked at 20 °C withyields of 0.35, 0.30 and 2.5 pg cell -1 ,but the highest yield (0.7 pg cell -1 ) ofCmTx-IV was at 30 °C. The yieldsof all CmTx components decreasedsharply at temperatures exceeding20 °C. The highest amount of thetoxin CmTx-IV (0.70 pg cell -1 ) wasalso at 150 µmol m -2 s -1 . Anegative correlation between growthrate and toxin production was foundin the strain.O.11-01The genetic basis for thebiosynthesis of PSTs incyanobacteria and algaeSession: O.11 - GeneticsPresentation time: 16:40 - 17:00R Kellmann 1 , YJ Jeon 2 , TK Mihali 2 , RCavaliere 2 , BA Neilan 21 University of Bergen, BERGEN, Norway2 University of New South Wales, SYDNEY,AustraliaResearch efforts are growingworldwide in an attempt tounderstand the ecophysiologicalmechanisms involved in theformation, control and spread oftoxic blooms, however little is knownabout the biosynthesis of algaltoxins, the identity of genes andenzymes involved, and how theyare regulated. Saxitoxin and itsanalogues, which are responsiblefor paralytic shellfish poisoning, areone of the most enigmatic groups ofalgal toxins. Although they aresynthesised by a complex andunique pathway, organisms fromtwo kingdoms, which are thedinoflagellates and cyanobacteria,are capable of producing the sametoxins. In spite of efforts over thelast 30 years, the identity of genesinvolved in this pathway haveremained a mystery. Here wepresent the genes that areresponsible for the biosynthesis ofsaxitoxin analogues incyanobacteria from the genera52