7 research outputs found
Maitotoxin-4, a Novel MTX Analog Produced by Gambierdiscus excentricus
Maitotoxins (MTXs) are among the most potent toxins known. These toxins are produced by epi-benthic dinoflagellates of the genera Gambierdiscus and Fukuyoa and may play a role in causing the symptoms associated with Ciguatera Fish Poisoning. A recent survey revealed that, of the species tested, the newly described species from the Canary Islands, G. excentricus, is one of the most maitotoxic. The goal of the present study was to characterize MTX-related compounds produced by this species. Initially, lysates of cells from two Canary Island G. excentricus strains VGO791 and VGO792 were partially purified by (i) liquid-liquid partitioning between dichloromethane and aqueous methanol followed by (ii) size-exclusion chromatography. Fractions from chromatographic separation were screened for MTX toxicity using both the neuroblastoma neuro-2a (N2a) cytotoxicity and Ca2+ flux functional assays. Fractions containing MTX activity were analyzed using liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) to pinpoint potential MTX analogs. Subsequent non-targeted HRMS analysis permitted the identification of a novel MTX analog, maitotoxin-4 (MTX4, accurate mono-isotopic mass of 3292.4860 Da, as free acid form) in the most toxic fractions. HRMS/MS spectra of MTX4 as well as of MTX are presented. In addition, crude methanolic extracts of five other strains of G. excentricus and 37 other strains representing one Fukuyoa species and ten species, one ribotype and one undetermined strain/species of Gambierdiscus were screened for the presence of MTXs using low resolution tandem mass spectrometry (LRMS/MS). This targeted analysis indicated the original maitotoxin (MTX) was only present in one strain (G. australes S080911_1). Putative maitotoxin-2 (p-MTX2) and maitotoxin-3 (p-MTX3) were identified in several other species, but confirmation was not possible because of the lack of reference material. Maitotoxin-4 was detected in all seven strains of G. excentricus examined, independently of their origin (Brazil, Canary Islands and Caribbean), and not detected in any other species. MTX4 may therefore serve as a biomarker for the highly toxic G. excentricus in the Atlantic area
Taxonomy of Gambierdiscus including four new species, Gambierdiscus caribaeus, Gambierdiscus carolinianus, Gambierdiscus carpenteri and Gambierdiscus ruetzleri (Gonyaulacales, Dinophyceae)
10.2216/07-15.1Phycologia485344-390PYCO
Molecular Approaches to the Study of Phytoplankton Life Cycles: Implications for Harmful Algal Bloom Ecology
Toxicity screening of 13 Gambierdiscus strains using neuro-2a and
Species in the epi-benthic dinoflagellate genus Gambierdiscus produce ciguatoxins (CTXs) and
maitotoxins (MTXs), which are among the most potent marine toxins known. Consumption of
fish
contaminated with sufficient quantities of CTXs causes Ciguatera Fish Poisoning (CFP), the largest cause
of non-bacterial food poisoning worldwide. Maitotoxins, which can be found in the digestive system of
fish, could also contribute to CFP if such tissues are consumed. Recently, an increasing number of
Gambierdiscus species have been identified; yet, little is known about the variation in toxicity among
Gambierdiscus strains or species.
This study is the
first assessment of relative CTX- and MTX-toxicity of Gambierdiscus species from areas
as widespread as the North-Eastern Atlantic Ocean, Pacific Ocean and the Mediterranean Sea. A total of 13
strains were screened: (i) seven Pacific strains of G. australes, G. balechii, G. caribaeus, G. carpenteri,
G. pacificus, G. scabrosus and one strain of an undetermined species (Gambierdiscus sp. Viet Nam), (ii)
five
strains from the North-Eastern Atlantic Ocean (two G. australes, a single G. excentricus and two G. silvae
strains), and (iii) one G. carolinianus strain from the Mediterranean Sea. Cell pellets of Gambierdiscus were
extracted with methanol and the crude extracts partitioned into a CTX-containing dichloromethane
fraction and a MTX-containing aqueous methanol fraction. CTX-toxicity was estimated using the neuro-
2a cytoxicity assay, and MTX-toxicity via a human erythrocyte lysis assay.
Different species were grouped into different ratios of CTX- and MTX-toxicity, however, the ratio was
not related to the geographical origin of species (Atlantic, Mediterranean, Pacific). All strains showed
MTX-toxicity, ranging from 1.5 to 86 pg MTX equivalents (eq) cell 1. All but one of the strains showed
relatively low CTX-toxicity ranging from 0.6 to 50 fg CTX3C eq cell 1. The exception was the highly toxic
G. excentricus strain from the Canary Islands, which produced 1426 fg CTX3C eq cell 1. As was true for
CTX, the highest MTX-toxicity was also found in G. excentricus. Thus, the present study confirmed that at
least one species from the Atlantic Ocean demonstrates similar toxicity as the most toxic strains from the
Pacific, even if the metabolites in
fish have so far been shown to be more toxic in the Pacific Ocean.Versión del edito
Ecological Aspects of Harmful Algal In Situ Population Growth Rates
14 pages, 4 figures, 2 tablesPeer reviewe