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
