title: Oyster's cells regulatory volume decrease: A new tool for evaluating the toxicity of low concentration hydrocarbons in marine waters.
abstract: 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 90min-period. When exposed to diluted seawater (osmolalities from 895 to 712mosmkg(-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 (8.4mgL(-1) during 24h). 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 biological hazards of micropollutants in the water.
authors.affiliation: Institut Supérieur des Sciences Appliquées et de Technologie de Mahdia, Université de Monastir, Tunisia.
authors.forename: Chiraz
authors.initials: C
authors.lastname: Ben Naceur
authors.affiliation: Université Bretagne Sud, FRE CNRS 3744, IRDL, 56017 Vannes, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Maxime
authors.affiliation: Institut Supérieur des Sciences Appliquées et de Technologie de Mahdia, Université de Monastir, Tunisia.
authors.forename: Hedi
authors.initials: H
authors.lastname: Ben Mansour
authors.affiliation: Université Bretagne Sud, FRE CNRS 3744, IRDL, 56017 Vannes, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Le Tilly
authors.affiliation: Université Bretagne Sud, FRE CNRS 3744, IRDL, 56017 Vannes, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Sire
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D048429:Cell Size / Q000187:drug effects; D049896:Crassostrea / Q000187:drug effects*; D005742:Gasoline / Q000032:analysis / Q000633:toxicity*; D005880:Gills / Q000166:cytology*; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D012623:Seawater / Q000737:chemistry; D014867:Water / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D015415:Biomarkers; D005742:Gasoline; D014874:Water Pollutants, Chemical; D014867:Water; D005982:Glutathione Transferase
keywords: Crassostrea gigas; Diesel fuel; Glutathione S-transferase; Marine environmental biomonitoring; Oyster cells; Regulatory volume decrease