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 2006catalase, and glutathione S-transferase) is shown.O.12-03Cytotoxic and genotoxic effectsof microcystins in mammaliancell lines.Session: O.12 - Toxicology 2Presentation time: 17:20 - 17:40E Dias 1 , P Pereira 1 , C Batoréu 2 , PJordan 1 , MJ Silva 11 National Health Institute, LISBON,Portugal2 Faculty of Pharmacy of Lisbon University,LISBON, PortugalMicrocystin-LR (MCLR) has beenrecognized as a tumor promoter.However, knowledge of itscarcinogenicity mechanismsremains largely unknown. In thiswork we evaluated the genotoxicpotential of microcystins inmammalian cell lines. Microcystinswere extracted from M. aeruginosaand purified by preparative liquidchromatography. Cytotoxicity tests(MTT reduction, LDH release) wereused to determine the sensitivity ofseveral cell lines (Vero, HepG2 andAML12) to MCLR (1.4-175 μg ml -1 ).Genotoxicity of MCLR (2-60 μg ml-1) in Vero cells were analyzed bythe micronucleus assay. MTT andLDH assays showed that MCLRhad dose- and time-dependentcytotoxic effects on all three celllines. However, Vero cells were themost sensitive, showing a 50%decrease in the viability afterexposure to 22 μg ml -1 of MCLR for24h. Above 48h, cell survivaldecreased more than 80%. Similareffects were obtained with the othercells after longer exposure (48-96h)to higher toxin concentrations (44-175μg ml -1 ). Preliminary results ofmicronuclei analysis in MCLRtreatedVero cells (= 20 μg ml -1 )revealed an aneugenic/clastogenicactivity. In summary, we identified apermanent cell line as a usefulmodel system for microcystinstoxicity/genotoxicity assessmentand we showed that MCLRpresents genotoxic properties. Thissupports previous suggestions thatmicrocystins can act as cancerinitiators.O.12-04Ecological implications ofcylindrospermopsin infreshwatersSession: O.12 - Toxicology 2Presentation time: 17:40 - 18:00M SeifertUniversity of Queensland, INALA, AustraliaThe potent cyanobacterial toxin,cylindrospermopsin, is beingincreasingly found in freshwatersaround the world. In addition, theproduction of the toxin, and itsanalogues deoxycylindrospermopsinand 7-epicylindrospermopsin,is beingreported from an increasing numberof cyanobacteria. In Queensland(Australia), Cylindrospermopsisraciborskii is the dominantcylindrospermopsin producingcyanobacterium and has beenimplicated as the causative agent inan instance of mass humanintoxication, numerous livestockmortalities and is considered amajor threat to drinking watersupplies. This has lead tosubstantial research into thecylindrospermopsin production, theremoval of the toxin from drinkingwaters and its toxicity to mammals.In contrast, the potential ecologicalimplications of C. raciborskii andcylindrospermopsin have beenlargely ignored. The QueenslandDepartment of Natural Resources,Mines and Water recognised this56