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 2006The congener was identified as adeoxy GTX4-12ol lacking an oxygenatom at position C12. This is thefirst report of the congener.PO.02-09Is application of quantitative-PCRpossible for measurements intoxic Microcystis populations?Session: PO.02 - GenomicsJZ Lin, HN ChouNational Taiwan University, TAIPEI, TaiwanSix characteristic segments,mcyA~E, and the promoter of themicrocystin synthetase genecluster, designed in a Quantitative-PCR amplification were applied forquantitative measurements of toxicpopulations in environmentalsamples. Observations during themethod-development experimentsagainst 8 toxic and 4 non-toxicclones of Microcystis were: (i) theexpected specific amplicons werefound in all toxic clones but wereabsent or less abundant in non-toxicclones; (ii) all the toxic clonesshowed consistent Tm values ofmcyD, implying this partial mcyDsegment as the most conservedamong the tested mcys; (iii) a linearcorrelation was obtained betweenthe microscopically determined cellnumbers and the PCR thresholdcycles; (iv) cell concentration of thetoxic Microcystis from Q-PCRmeasurement was not affected byaddition of non-toxic populations; (v)gene copy number per cell wasvariable during the different growthstages and a maximal of 20 at theearly logarithmic and stationaryphase of batch cultures of toxicMicrocystis. This Q-PCR can beapplied in the environmentalsamples to as few as 800 toxiccells. The selection of suitableprimer pairs for specific mcysegments is important to avoidmisleading results.PO.10-01Effects of UVBR on differentstrains of the cyanobacteriumNodularia spumigena from theBaltic SeaSession: PO.10 - Ecophysiology &autecologyV Lindberg, M Mohlin, A WulffGöteborg University, GÖTEBORG, SwedenNodularia spumigena is one ofseveral toxin-producingcyanobacteria in the Baltic Sea. Itproduces the hepatoxin nodularin, atumour promoter known to havekilled wild and domestic animals.Nodularia spumigena blooms occurduring late summer, a period withstrong light, calm weather andstable water-column stratification.The tolerance to high lightintensities of three different strainsof N. spumigena was tested for 10days in two different laboratoryexperiments. Cultures were kept insemi-continuous growth andexposed to UVBR and UVAR, up to0.8 W/m 2 and 5 W/m 2 , respectively.Variables measured: growth (lightmicroscope), photosyntheticcapacity (phyto-PAM, Walz),content and composition ofphotosynthetic pigments, phycobilinpigments and UV-absorbingcompounds (HPLC). Despite sometreatment effects, UVBR intensitiesup to 0.4 W/m 2 do not seem to havea negative impact on the threestrains on day 10. However, whenexposed to UVBR intensities up to0.8 W/m 2 all strains were to someextent negatively affected by alower maximum quantum yield ofphotosynthesis but not growth. Inconclusion, this toxiccyanobacterium appear to have the221