TY - JOUR T1 - Evidence of the bioaccumulation of ciguatoxins in giant clams (Tridacna maxima) exposed to Gambierdiscus spp. cells A1 - Roue,Melanie A1 - Darius,Helene Taiana A1 - Picot,Sandy A1 - Ung,Andre A1 - Viallon,Jerome A1 - Gaertner-Mazouni,Nabila A1 - Sibat,Manoella A1 - Amzil,Zouher A1 - Chinain,Mireille AD - IRD, UMR EIO 241, POB 529, F-98713 Papeete, Tahiti, Fr Polynesia. AD - ILM, Lab Tox Microalgae UMR EIO 241, POB 30, F-98713 Papeete, Tahiti, Fr Polynesia. AD - UPF, UMR EIO 241, POB 6570, F-98702 Faaa, Tahiti, France. AD - IFREMER, Phycotoxins Lab, POB 21105, F-44311 Nantes, France. UR - https://doi.org/10.1016/j.hal.2016.05.007 DO - 10.1016/j.hal.2016.05.007 KW - Giant clams KW - Ex situ contamination KW - Ciguatoxins KW - Gambierdiscus polynesiensis KW - LC-MS/MS KW - Neuroblastoma cell-based assay N2 - Ciguatera Fish Poisoning (CFP) is a foodborne disease classically related to the consumption of tropical coral reef fishes contaminated with ciguatoxins (CTXs), neurotoxins produced by dinoflagellates of the Gambierdiscus genus. Severe atypical ciguatera-like incidents involving giant clams, a marine resource highly consumed in the South Pacific, are also frequently reported in many Pacific Islands Countries and Territories. The present study was designed to assess the ability of giant clams to accumulate CTXs in their tissues and highlight the potential health risks associated with their consumption. Since giant clams are likely to be exposed to both free-swimming Gambierdiscus cells and dissolved CTXs in natural environment, ex situ contamination experiments were conducted as follows: giant clams were exposed to live or lyzed cells of TB92, a highly toxic strain of G. polynesiensis containing 5.83 ± 0.85 pg P-CTX-3C equiv. cell−1vs. HIT0, a weakly toxic strain of G. toxicus containing only (2.05 ± 1.16) × 10−3 pg P-CTX-3C equiv. cell−1, administered over a 48 h period at a concentration of 150 cells mL−1. The presence of CTXs in giant clams tissues was further assessed using the mouse neuroblastoma cell-based assay (CBA-N2a). Results showed that giant clams exposed to either lyzed or live cells of TB92 were able to bioaccumulate CTXs at concentrations well above the safety limit recommended for human consumption, i.e. 3.28 ± 1.37 and 2.92 ± 1.03 ng P-CTX-3C equiv. g−1 flesh (wet weight), respectively, which represented approximately 3% of the total toxin load administered to the animals. In contrast, giant clams exposed to live or lyzed cells of HIT0 were found to be free of toxins, suggesting that in the nature, the risk of contamination of these bivalves is established only in the presence of highly toxic blooms of Gambierdiscus. Liquid chromatography–mass spectrometry (LC–MS/MS) analyses confirmed CBA-N2a results and also revealed that P-CTX-3B was the major CTX congener retained in the tissues of giant clams fed with TB92 cells. To the best of our knowledge, this study is the first to provide evidence of the bioaccumulation of Gambierdiscus CTXs in giant clams and confirms that these bivalve molluscs can actually constitute another pathway in ciguatera poisonings. While most monitoring programs currently focus on fish toxicity, these findings stress the importance of a concomitant surveillance of these marine invertebrates in applicable locations for an accurate assessment of ciguatera risk. Y1 - 2016/07 PB - Elsevier Science Bv JF - Harmful Algae SN - 1568-9883 VL - 57 IS - Part. A SP - 78 EP - 87 ID - 45415 ER -