Toxicological Investigations on the Sea Urchin Tripneustes gratilla (Toxopneustidae, Echinoid) from Anaho Bay (Nuku Hiva, French Polynesia): Evidence for the Presence of Pacific Ciguatoxins.

Hélène Taiana Darius,Manoella Sibat,R Wayne Litaker,Mireille Chinain,Jérôme Viallon,Mélanie Roué,Clémence Mahana Iti Gatti,Philipp Hess,Zouher Amzil,Patricia A Tester,Mark W Vandersea

doi:10.3390/md16040122

Abstract

The sea urchin Tripneustes gratilla (Toxopneustidae, Echinoids) is a source of protein for many islanders in the Indo-West Pacific. It was previously reported to occasionally cause ciguatera-like poisoning; however, the exact nature of the causative agent was not confirmed. In April and July 2015, ciguatera poisonings were reported following the consumption of T. gratilla in Anaho Bay (Nuku Hiva Island, Marquesas archipelago, French Polynesia). Patient symptomatology was recorded and sea urchin samples were collected from Anaho Bay in July 2015 and November 2016. Toxicity analysis using the neuroblastoma cell–based assay (CBA-N2a) detected the presence of ciguatoxins (CTXs) in T. gratilla samples. Gambierdiscus species were predominant in the benthic assemblages of Anaho Bay, and G. polynesiensis was highly prevalent in in vitro cultures according to qPCR results. Liquid chromatography–tandem mass spectrometry (LC-MS/MS) analyses revealed that P-CTX-3B was the major ciguatoxin congener in toxic sea urchin samples, followed by 51-OH-P-CTX-3C, P-CTX-3C, P-CTX-4A, and P-CTX-4B. Between July 2015 and November 2016, the toxin content in T. gratilla decreased, but was consistently above the safety limit allowed for human consumption. This study provides evidence of CTX bioaccumulation in T. gratilla as a cause of ciguatera-like poisoning associated with a documented symptomatology.

Highlights

Tripneustes gratilla Linnaeus, 1758 (Echinoidea, Temnopleuroida, Toxopneustidae) (Figure 1) is a fast-growing echinoid found in isolated populations throughout the warm temperate Indo-PacificMar
All of them presented at the hospital on Nuku Hiva Island with a poisoning syndrome evocative of ciguatera poisoning after consuming T. gratilla specimens
Among eight clonal cultures tested, two strains of G. carpenteri (NHA19 and NAH20) were nontoxic, whereas four strains of G. polynesiensis and two strains of G. pacificus displayed CTX-like toxic activity on neuroblastoma cells; i.e., all six liposoluble fractions showed no cytotoxicity under OV− conditions versus a sigmoidal dose-response curve in OV+ conditions, a response typical of CTX bioactivity (Figure 3)

Summary

Introduction

Tripneustes gratilla Linnaeus, 1758 (Echinoidea, Temnopleuroida, Toxopneustidae) (Figure 1) is a fast-growing echinoid found in isolated populations throughout the warm temperate Indo-Pacific. Mar. Drugs 2018, 16, 122; doi:10.3390/md16040122 www.mdpi.com/journal/marinedrugs. Mar. Drugs 2018, 16, 122 region [1]. Tripneustes species are mostly grazers of sea grasses in tropical regions [3,4] and macroalgae in more temperate regions [1,5]. Sea urchins must ingest and process large quantities of macroalgae and/or sea grass to meet their nutritional requirements for protein [6]. According to Byrne et al, 2008 [7], Tripneustes species are ecologically important, especially in sea grass habitats, and are often keystone species as primary herbivores

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Conclusion