Toxicology of Gambierdiscus spp. (Dinophyceae) from Tropical and Temperate Australian Waters.

Michaela Larsson,Martina Doblin,Olivier Laczka,D Harwood,Shauna Murray,Richard Lewis,S Himaya

doi:10.3390/md16010007

Abstract

Ciguatera Fish Poisoning (CFP) is a human illness caused by the consumption of marine fish contaminated with ciguatoxins (CTX) and possibly maitotoxins (MTX), produced by species from the benthic dinoflagellate genus Gambierdiscus. Here, we describe the identity and toxicology of Gambierdiscus spp. isolated from the tropical and temperate waters of eastern Australia. Based on newly cultured strains, we found that four Gambierdiscus species were present at the tropical location, including G. carpenteri, G. lapillus and two others which were not genetically identical to other currently described species within the genus, and may represent new species. Only G. carpenteri was identified from the temperate location. Using LC-MS/MS analysis we did not find any characterized microalgal CTXs (P-CTX-3B, P-CTX-3C, P-CTX-4A and P-CTX-4B) or MTX-1; however, putative maitotoxin-3 (MTX-3) was detected in all species except for the temperate population of G. carpenteri. Using the Ca2+ influx SH-SY5Y cell Fluorescent Imaging Plate Reader (FLIPR) bioassay we found CTX-like activity in extracts of the unidentified Gambierdiscus strains and trace level activity in strains of G. lapillus. While no detectable CTX-like activity was observed in tropical or temperate strains of G. carpenteri, all species showed strong maitotoxin-like activity. This study, which represents the most comprehensive analyses of the toxicology of Gambierdiscus strains isolated from Australia to date, suggests that CFP in this region may be caused by currently undescribed ciguatoxins and maitotoxins.

Highlights

Ciguatera Fish Poisoning (CFP) is a human illness which arises from the consumption of marine fish contaminated with ciguatoxins (CTX) [1]
Three strains (UTSHI6B5, UTSHI2B6, UTSHI2B5) group with high support in the large subunit (LSU) rDNA D8–D10 region phylogeny with G. lapillus (Figure 1b), a new species described from the same tropical location in eastern Australia (Heron Island) [58]
Extracts of three species showed CTX-like activity, likely caused by compounds which are distinct from currently characterized toxins

Summary

Introduction

Ciguatera Fish Poisoning (CFP) is a human illness which arises from the consumption of marine fish contaminated with ciguatoxins (CTX) [1]. 200,000 people each year are affected [2], making it the most prevalent nonbacterial human illness associated with seafood consumption [3,4]. The risk of CFP is higher in tropical locations and is prevalent among island communities who rely on seafood for survival [5,6], affecting up to per 100,000 people each year [7]. With the onset of international travel and worldwide seafood trade, this foodborne syndrome has become a global issue [8,9,10]. Some species of dinoflagellates from the genus Gambierdiscus produce CTXs, the causative agents of CFP [11]. Adachi and Fukuyo [12] originally described Gambierdiscus toxicus, the first species in the

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