Assessment of cytotoxicity in ten strains of Gambierdiscus australes from Macaronesian Islands by neuro-2a cell-based assays

Ciguatera poisoning (CP) results from the consumption of seafood contaminated with ciguatoxins (CTXs). This disease is highly prevalent in French Polynesia with several well-identified hotspots. Rapa Island, the southernmost inhabited island in the country, was reportedly free of CP until 2007. This study describes the integrated approach used to investigate the etiology of a fatal mass-poisoning outbreak that occurred in Rapa in 2009. Symptoms reported in patients were evocative of ciguatera. Several Gambierdiscus field samples collected from benthic assemblages tested positive by the receptor binding assay (RBA). Additionally, the toxicity screening of ≈250 fish by RBA indicated ≈78% of fish could contain CTXs. The presence of CTXs in fish was confirmed by liquid chromatography tandem mass spectrometry (LC-MS/MS). The potential link between climate change and this range expansion of ciguatera to a subtropical locale of French Polynesia was also examined based on the analysis of temperature time-series data. Results are indicative of a global warming trend in Rapa area. A five-fold reduction in incidence rates was observed between 2009 and 2012, which was due in part to self-regulating behavior among individuals (avoidance of particular fish species and areas). Such observations underscore the prominent role played by community outreach in ciguatera risk management.

Section: Introductionmentioning

confidence: 57%

Evidence for the Range Expansion of Ciguatera in French Polynesia: A Revisit of the 2009 Mass-Poisoning Outbreak in Rapa Island (Australes Archipelago)

Chinain

Gatti

Ung

et al. 2020

“…The enhanced growth rate observed in this study likely results from the stabilization of pH in the cultures over the duration of the experiments. Several studies have examined the toxin production patterns in relation to growth rates in various Gambierdiscus species such as G. polynesiensis, G. excentricus, G. australes, and G. carpenteri, and concluded to a higher toxin biosynthesis in strains/species with low reproductive rates [24,44,54,67,82]. These findings suggest a trade-off between investments of cellular resources in growth vs. the production of defensive compounds [24,54], a pattern also described in another closely related harmful algal species, Karenia brevis [83,84].…”

Section: Discussionmentioning

confidence: 99%

Intraspecific Variability in the Toxin Production and Toxin Profiles of In Vitro Cultures of Gambierdiscus polynesiensis (Dinophyceae) from French Polynesia

Longo

Sibat

Viallon

et al. 2019

Ciguatera poisoning (CP) is a foodborne disease caused by the consumption of seafood contaminated with ciguatoxins (CTXs) produced by dinoflagellates in the genera Gambierdiscus and Fukuyoa. The toxin production and toxin profiles were explored in four clones of G. polynesiensis originating from different islands in French Polynesia with contrasted CP risk: RIK7 (Mangareva, Gambier), NHA4 (Nuku Hiva, Marquesas), RAI-1 (Raivavae, Australes), and RG92 (Rangiroa, Tuamotu). Productions of CTXs, maitotoxins (MTXs), and gambierone group analogs were examined at exponential and stationary growth phases using the neuroblastoma cell-based assay and liquid chromatography–tandem mass spectrometry. While none of the strains was found to produce known MTX compounds, all strains showed high overall P-CTX production ranging from 1.1 ± 0.1 to 4.6 ± 0.7 pg cell−1. In total, nine P-CTX analogs were detected, depending on strain and growth phase. The production of gambierone, as well as 44-methylgamberione, was also confirmed in G. polynesiensis. This study highlighted: (i) intraspecific variations in toxin production and profiles between clones from distinct geographic origins and (ii) the noticeable increase in toxin production of both CTXs, in particular CTX4A/B, and gambierone group analogs from the exponential to the stationary phase.

“…A previous study showed that toxicity is more closely related to genetics rather than to environmental (temperature, ph and salinity) factors [44]. Among Gambierdiscus species in the Canary Islands, both G. excentricus [45,46] and G. australes [47] are known to produce high levels of CTX. However, information on other regional members of this genus is scarce.…”

Section: Introductionmentioning

confidence: 98%

Toxicity Characterisation of Gambierdiscus Species from the Canary Islands

Rossignoli

Tudó

Bravo

et al. 2020

Self Cite

In the last decade, several outbreaks of ciguatera fish poisoning (CFP) have been reported in the Canary Islands (central northeast Atlantic Ocean), confirming ciguatera as an emerging alimentary risk in this region. Five Gambierdiscus species, G. australes, G. excentricus, G. silvae, G. carolinianus and G. caribaeus, have been detected in macrophytes from this area and are known to produce the ciguatoxins (CTXs) that cause CFP. A characterization of the toxicity of these species is the first step in identifying locations in the Canary Islands at risk of CFP. Therefore, in this study the toxicity of 63 strains of these five Gambierdiscus species were analysed using the erythrocyte lysis assay to evaluate their maitotoxin (MTX) content. In addition, 20 of the strains were also analysed in a neuroblastoma Neuro-2a (N2a) cytotoxicity assay to determine their CTX-like toxicity. The results allowed the different species to be grouped according to their ratios of CTX-like and MTX-like toxicity. MTX-like toxicity was especially high in G. excentricus and G. australes but much lower in the other species and lowest in G. silvae. CTX-like toxicity was highest in G. excentricus, which produced the toxin in amounts ranging between 128.2 ± 25.68 and 510.6 ± 134.2 fg CTX1B equivalents (eq) cell−1 (mean ± SD). In the other species, CTX concentrations were as follows: G. carolinianus (100.84 ± 18.05 fg CTX1B eq cell−1), G. australes (31.1 ± 0.56 to 107.16 ± 21.88 fg CTX1B eq cell−1), G. silvae (12.19 ± 0.62 to 76.79 ± 4.97 fg CTX1B eq cell−1) and G. caribaeus (<LOD to 90.37 ± 15.89 fg CTX1B eq cell−1). Unlike the similar CTX-like toxicity of G. australes and G. silvae strains from different locations, G. excentricus and G. caribaeus differed considerably according to the origin of the strain. These differences emphasise the importance of species identification to assess the regional risk of CFP.