@phdthesis{52635, type = "Thesis", year = "2017", title = "Criblage bioguidé et analyse CL - SMHR des toxines et d'au tres métabolites d'intérêt chez les dinoflagellés G ambierdiscus et Fukuyoa, Bioguided screening and LC-HRMS for identification of toxins and other metabolites of interest produced by the dinoflagellates Gambierdiscus and Fukuyoa", journal = "", editor = "", volume = "", number = "", pages = "", author = "Pisapia Francesco", url = "https://archimer.ifremer.fr/doc/00415/52635/", organization = "", address = "FRANCE", school = "Université de Nantes", abstract = "
The epi-benthic dinoflagellates Gambierdiscus and Fukuyoa produce ciguatoxins (CTXs) and maitotoxins (MTXs), which are among the most potent marine toxins known. CTXs are bio-accumulated and bio-transformed along the marine food chain and cause Ciguatera Fish Poisoning (CFP), the most common non-bacterial foodborne intoxication worldwide. Recently, CFP has been reported from areas previously not considered endemic, namely the Canary Islands, and an increasing number of species has been discovered in these genera. Little is known about the relative toxicity between different species and the toxin congeners produced by these dinoflagellates, especially by strains outside the Pacific Ocean. Several strains of Gambierdiscus and Fukuyoa were screened for their cigua- and maito-toxicity using neuro-2a and hemolytic assays, respectively. G. excentricus showed particularly high toxicity and two strains from Canary Islands were selected for toxin purification using a bioguided fractionation approach. Non-targeted high resolution mass spectrometry (MS) analysis permitted the discovery of a novel MTX congener, maitotoxin-4 (MTX4). Targeted low resolution MS analysis of more than 40 strains of Gambierdiscus and Fukuyoa revealed the presence of MTX4 in G. excentricus only, including strains from the Canaries, the South Western Atlantic (Brazil) and the North Western Atlantic (Gulf of Mexico). As MTX4 was not detected in any other species examined, MTX4 may serve as a biomarker for the highly toxic G. excentricus. Future work will include isolation and structural elucidation of MTX4 and identification of CTX congeners produced by G. excentricus.
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