Étude des mécanismes de contamination des mollusques bivalves par des neurotoxines à action rapide (FAT) & développement de procédés de détoxification.

• Main Author: Walid, Medhioub
• Other Authors: Laboratoire Phycotoxine, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Laboratoire d’Aquaculture Marine et Continentale Monastir (INSTM), Institut National des Sciences et Technologies de la Mer Salammbô (INSTM), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Bretagne occidentale - Brest, Philippe Soudant/Mejeddine Kraeim([e-mail]/[e-mail])
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2011
• Subjects: histology; Karenia selliformis; gymnodimine; Ruditapes decussatus; Alexandrium ostenfeldii; spirolide; Crassostrea gigas; culture; détoxification; histologie; [SDV.MHEP.PHY]Life Sciences [q-bio]/Human health and pathology/Tissues and Organs [q-bio.TO]
• Online Access: https://tel.archives-ouvertes.fr/tel-00598247; https://tel.archives-ouvertes.fr/tel-00598247/document; https://tel.archives-ouvertes.fr/tel-00598247/file/MS_ThA_se_MW-Finale.pdf

This study aimed to determine the optimal conditions of growth and toxin production in Karenia selliformis and Alexandrium ostenfeldii in order to produce cells at a high concentration with known toxicity to perform further contamination and detoxification trial on edible shellfish. Moreover, this work aims to study the impact of non-toxic microalga on the detoxification kinetics of clam Ruditapes decussatus contaminated by gymnodimines and oyster Crassostrea gigas contaminated by spirolides. The final goal of this study is to determine the physiological impact of toxic microalgae in the shellfish tissues. Initially, results revealed that the growth performance of K. selliformis (growth rate and maximum concentration) is obtained at a temperature of 22°C and at a salinity of 36 psu when using the f/2 medium, while those of A. ostenfeldii are obtained at a temperature of 16°C and at a salinity of 35 psu using the L1 medium. Gymnodimine concentration increases with the age of the culture of K. selliformis while spirolide concentration decreases during cell growth of A. ostenfeldii especially during the culture in a photobioreactor of 100 l. Secondly, the experimental studies focused on the interaction between toxic micro-algae with molluscs bivalves. The results revealed i) a major accumulation of GYMs and SPXs in digestive gland of clams and oysters ii) a rapid detoxification of contaminated shellfish when adding food. Finally, this study addressed an important issue on the impact of toxic algae on shellfish. The exposure to A. ostenfeldii showed i) a decrease in the digestive gland tubule thickness and the percentage of active digestive tubules ii) an inflammatory response consisting of hemocyte infiltration and diapedesis into the intestinal tract of the oysters. Concerning the natural and experimental contamination of clams, histological analysis did not reveal any alteration of the digestive gland as demonstrated in oysters contaminated by A. ostenfeldii. Cette étude à pour objectif de maîtriser les ...