New strategies in the fight against Ciguatera

International audienceCiguatera is the major cause of food poisonings by seafood worldwide, with an estimated 50 000 to 500 000 victims per year. It is caused by very potent neurotoxins, Ciguatoxins which are lipid-soluble polyether compounds produced by dinoflagellates from the genus Gambierdiscus spp.. Ciguatoxins are mostly found in tropical and subtropical zones, including notably the Caribbean’s, French Polynesia, New Caledonia, Indian Ocean and Southern Asia. Within the last decade, they have been also identified in fishes caught in European waters (ex.: in Madeira and Canary Islands), while Gambierdiscus spp. have also been found both in the NE Atlantic Ocean and in the Mediterranean Sea. Ciguatoxins bind to Voltage Gated Sodium Channels at the surface of human sensory neurons where they remain, causing Ciguatera Fish Poisoning or CFP. This severe disease is characterized by with a variety of gastrointestinal, cardiovascular and neurological symptoms (paresthesia, ataxia, cold allodynia), including persistent neurological effects. Despite the importance and prevalence of CFP, there is so far no simple and quick way of detecting these toxins in contaminated samples. Currently, only heavy and expensive laboratory methods are available to detect them: LC-MS/MS, receptor-binding assays by competition with radiolabeled compounds, and neuroblastoma cell-based assays performed on mammalian neurons. We have started to engineer biosensors based on the detection of a transcriptional signal in the yeast model Saccharomyces cerevisiae. This unicellular eukaryotic model is well-known and easy to genetically modify, grows fast and presents a very good conservation of signaling pathways with higher eukaryotes. Moreover, in an attempt to use developing Nanobiotechnology approaches, we will present our current strategy to study and characterize the binding of Ciguatoxins on mammalian neuronal cells by Single Molecule Force Spectroscopy using AFM