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 2006It is highly possible thatmacromolecules are involved in thetransportation and the accumulationof saxitoxins in marine organisms.As an efficient tool to detect themacromolecules having affinity tosaxitoxins, we developed saxitoxinconjugatedaffinity gel. In thispaper, we report the 1st trial to testits efficiency using the extract ofscallop Patinopecten yessoensis.The mantle was chosen as thetarget organ because it retained thetoxins much longer than otherorgans.The affinity gel and a controlacetylated gel without toxin-ligandwere prepared according to thepreviously reported procedures.The extracts of toxic and non-toxicscallop samples were fractionatedwith two types of gel in spincolumnsand the retained proteinswere compared by SDS-PAGE.Several specific bands detected inthe samples were analyzed withpeptide-mass fingerprinting methodand identified by the search engineMS-Fit based on NBCInr. database.So far, tropomyosins were found ascandidate proteins. The actual toxinbinding properties and the role intoxin accumulation of them are nowunder investigation. Since theprocedure is simple and requiresonly short period, it will be aneffective tool as the first screeningfor saxitoxin-binding proteins.O.01-06Amphidinols and karlotoxins –brothers in arms part deux:structural similaritiesSession: O.01 - Toxin synthesisPresentation time: 12:40 - 13:00AR Place 1 , JE Adolf 1 , TR Bachvaroff 1 ,JE Peng 2 , MT Hamann 21 University of Maryland Biotechnology Ins,BALTIMORE, MARYLAND, United Statesof America2 University of Mississippi, UNIVERSITY,MS 38677, United States of AmericaAmphidinols have commonstructural features characterized by2 ether rings, 7 double bondsinvolving a conjugated triene and anexomethylene, a branching methyl,an olefinic methyl, and polyhydroxylgroups. We recently finished theplanar structure of karlotoxin-2(KmTx2) which was found to have amolecular formula ofC67H121ClO24. KmTx2 contained2 ether rings, 5 double bondsinvolving a conjugated diene andexomethylene, a branching methyl,and polyhydroxyl groups. Noolefinic methyl group was found. Asulphated derivative of KmTx2 (inthe hydrophilic segment) was alsoisolated and found to be significantlyless toxic. The determination of therelative and absolute configurationof the polyhydroxyl linear molecularof KmTx2 remains to be completedand will be reported in due course.Given these extensive structuralsimilarities the biological activities ofamphidinols and karlotoxins arealso remarkably similar. Both toxinsshow sterol dependent antifungal,cytotoxic and hemolytic activities inthe submicromolar range.Karlotoxins are also ichthyotoxic atconcentrations less than 0.2 µg/ml.Based on experimental datagathered from Karlodinium wehypothesize that both groups oftoxins have evolved to assist inpredator avoidance and preycapture for mixotrophic growth.28