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 2006characteristics or by DNA sequencedivergence. The North Americanclade, as defined by its LSUribosomal DNA sequence, is themost widely distributedrepresentative of the PSP toxinproducingA. tamarense clades.Populations of this clade causerecurrent blooms in many regions ofthe world. Natural populations fromNorth America, Northern Europeand Japan exhibit notable geneticdifferentiation that can be detectedby molecular markers with differentresolution properties. Whereasmolecular sequence analysis ofribosomal DNA yields only a coarseresolution pattern of regionalsubclades, mitochondrial DNAsequences and microsatellites, aswell as Amplified Fragment LengthPolymorphism (AFLP) analysis,allow the estimation of geneticdifferentiation between contiguouspopulations. No congruence of anyof the genetic markers were foundbetween the expression of PSPtoxin phenotypes or allelochemicalproperties that can affect grazers orcompeting algal species, but interpopulationdifferences in PSP toxinprofile were apparent on a broadgeographical scale. The variableexpression of the allelopathicphenotype within a population fromNorthern Europe was used toexperimentally test the protectivebenefit of allelochemical propertieson bloom formation.O.11-04Genetic differences betweenKarlodinium veneficum strains:using DNA variation tounderstand strain variation at thebloom, regional and worldwidelevelSession: O.11 - GeneticsPresentation time: 17:40 - 18:00TR BachvaroffUMBI, BALTIMORE, United States ofAmericaKarlodinium veneficum is a toxicbloom forming dinoflagellate foundin estuarine systems throughout theworld. Strains from the U. S. Atlanticcoast (24 strains), the North Sea (3)and the Pacific (3) as well as asingle Mediterranean strain wereused to understand the geneticbasis of the wide range of karlotoxintypes and cellular quotas observedamong strains of K. veneficum. Thephenotype is expressed asdifferences in toxin (pg) per cell,toxin type, and pigment tochlorophyll ratios. Differences ingenotype were determined usinggenetic loci isolated from a library ofenriched repeat sequences. TheITS sequence and pigment ratioscan distinguish between U.S.Atlantic coast strains and Europeanor Pacific isolates. Simple sequencerepeats, or microsatellite loci candistinguish among the U.S. strains.Further, one marker, KvF4 yields a485 bp fragment for U.S.Chesapeake Bay strains producingkarlotoxin 1 while the same locusyields a 283 bp fragment for allother US strains producingkarlotoxin 2. Generally, thesegenetic markers can be divided intothose useful for distinguishingbetween different isolates from thesame bloom, those that distinguishstrains from the same region, andthose that distinguish betweenstrains from different parts of theworld.O.12-01In vivo exposure to microcystinsinduced DNA damage inhaemocytes of the zebra musselas measured with the Cometassay54