Oyster's cells regulatory volume decrease A new tool for evaluating the toxicity of low concentration hydrocarbons in marine waters

• Published in: Ecotoxicology and Environmental Safety
• Main Authors: Ben Naceur, Chiraz, Maxime, Valerie, Ben Mansour, Hedi, Le Tilly, Veronique, Sire, Olivier
• Other Authors: Université de Monastir - University of Monastir (UM), Institut de Recherche Dupuy de Lôme (IRDL), Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Université de Bretagne Sud (UBS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: Marine environmental biomonitoring; Diesel fuel; Crassostrea gigas; Regulatory volume decrease; Glutathione S-transferase; Oyster cells; [CHIM.MATE]Chemical Sciences/Material chemistry
• Online Access: https://hal.archives-ouvertes.fr/hal-02110760; https://doi.org/10.1016/j.ecoenv.2016.07.030

Human activities require fossil fuels for transport and energy, a substantial part of which can accidentally or voluntarily (oil spillage) flow to the marine environment and cause adverse effects in human and ecosystems' health. This experiment was designed to estimate the suitability of an original cellular biomarker to early quantify the biological risk associated to hydrocarbons pollutants in seawater. Oocytes and hepatopancreas cells, isolated from oyster (Crassostrea gigas), were tested for their capacity to regulate their volume following a hypo-osmotic challenge. Cell volumes were estimated from cell images recorded at regular time intervals during a 90 min-period. When exposed to diluted seawater (osmolalities from 895 to 712 mosm kg(-1)), both cell types first swell and then undergo a shrinkage known as Regulatory Volume Decrease (RVD). This process is inversely proportional to the magnitude of the osmotic shock and is best fitted using a first-order exponential decay model. The Recovered Volume Factor (RVF) calculated from this model appears to be an accurate tool to compare cells responses. As shown by an about 50% decrease in RVF, the RVD process was significantly inhibited in cells sampled from oysters previously exposed to a low concentration of diesel oil (8.4 mg L-1 during 24 h). This toxic effect was interpreted as a decreased permeability of the cell membranes resulting from an alteration of their lipidic structure by diesel oil compounds. In contrast, the previous contact of oysters with diesel did not induce any rise in the gills glutathione S-transferase specific activity. Therefore, this work demonstrates that the study of the RVD process of cells selected from sentinel animal species could be an alternative bioassay for the monitoring of hydrocarbons and probably, of various chemicals in the environment liable to alter the cellular regulations. Especially, given the high sensitivity of this biomarker compared with a proven one, it could become a relevant and accurate tool to estimate the ...