Some Basic Methods in Respiratory Physiology Studies Applied in the Siberian Sturgeon

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Acid-Base Balance and Ammonia Loading in the Siberian Sturgeon Acipenser baerii, Exposed to High Concentrations of Ammonia

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Oxygen Demand in Sturgeon Farming

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Consequences of High Levels of Ammonia Exposure on the Gills Epithelium and on the Haematological Characteristics of the Blood of the Siberian Sturgeon, Acipenser baerii

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Effects of hyposmotic stress on exocytosis in isolated turbot, Scophthalmus maximus, hepatocytes

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Effects of hypo‐osmotic stress on ATP release in isolated turbot ( Scophthalmus maximus ) hepatocytes

International audienceBackground information . ATP is released from many cell types exposed to hypo‐osmotic shock and is involved in RVD (regulatory volume decrease). Purinergic signalling events have been extensively investigated in mammals, but not in marine teleosteans. Results . The effect of hypo‐osmotic shock on ATP release was examined in isolated hepatocytes from turbot ( Scophthalmus maximus ), a marine flatfish. Hypo‐osmotic stress (240 mOsm·kg −1 ) induced a significant increase in ATP efflux, and was inhibited by a potential CFTR (cystic fibrosis transmembrane conductance regulator) inhibitor, glibenclamide, but not by the MDR1 (multidrug resistance 1) P‐glycoprotein inhibitor, verapamil. ATP efflux could be a cAMP‐dependent process, as IBMX (isobutylmethylxanthine) and forskolin triggered the process under iso‐osmotic conditions. Protein kinases, including protein kinase C, could also be involved, as staurosporine and chelerythrine inhibited the mechanism. Calcium could contribute to ATP efflux as ionomycin, a calcium ionophore, elicited a rapid release under iso‐osmotic conditions, and chelation using EGTA abolished ATP release under hypo‐osmotic conditions. RVD was partially abolished by apyrase, an ATP scavenger, and suramin, a purinoceptor antagonist. Moreover, hypo‐osmotic shock induced a rise in intracellular calcium which could be involved in RVD. Since extracellular ATP triggered an increase in cellular free‐calcium content under iso‐osmotic conditions, our results could indicate that hypo‐osmotic‐induced ATP efflux contributes to RVD in turbot hepatocytes by stimulating purinergic receptors, which may lead to activation of a calcium signalling pathway. Conclusions . These data provide the first evidence of volume‐sensitive ATP signalling for volume maintenance in a marine teleost fish cell type

Evaluation of chromosomal damage by flow cytometry in turbot (Scophthalmus maximus L.) exposed to fuel oil.

International audienceFlatfishes, turbots (Scophthalmus maximus), were injected intraperitoneally with two doses of fuel oil number 2. Biliary metabolites were evaluated by fixed fluorescence to verify the efficiency of intoxication. Ethoxyresorufin-O-deethylase (EROD) activity was compared with chromosomal damage measured by flow cytometry. The analysis of biliary metabolites showed a good dose-response relation and constitutes a clear reference for the subsequent measurements. Comparing flow cytometry and EROD results, a shorter delay of response for EROD activity was obtained, but chromosomal damage was significant only after one week. The persistence of the EROD response was shorter, while the genotoxic signal still persisted after one month. The measurement of chromosomal damage allowed a good differentiation between the two tested doses. In the case of EROD activity, the results were less clear. The results suggest that within a few weeks after exposure to fuel oil number 2, the measurements of chromosomal damage by flow cytometry can be used to detect a dose-dependent genotoxic response in fish

Volume regulation following hyposmotic shock in isolated turbot (Scophthalmus maximus) hepatocytes.

International audienceRegulatory volume decrease (RVD) following hyposmotic stimulation was studied in isolated turbot, Scophthalmus maximus, hepatocytes. Exposed to a reduced osmolality (from 320 to 240 mosm kg(-1)), cells first swelled and then exhibited a RVD. Volume regulation was significantly inhibited in presence of NPPB, 9-AC, acetazolamide, DIDS and barium. Taken together, these results could suggest that RVD operated via separate K+ and Cl- channels and probably Cl-/HCO3(-) exchanger in turbot hepatocytes. The K+/Cl- cotransporter could also be involved as furosemide and DIOA strongly inhibited the process whereas NEM, a K+/Cl- cotransporter activator, added under isosmotic conditions, led to cell shrinkage. RVD in turbot hepatocytes appeared also to depend on proteins p38 MAP kinase and tyrosine kinase but not on proteins ERK 1/2. Arachidonic acid and leukotrienes could also be involved since inhibition of synthesis of both these compounds by quinacrine and NDGA, respectively, inhibited the volume regulation. Likewise, Ca2+ has been proved to be an essential messenger as RVD was prevented in absence of Ca2+. Finally, this work provides bases for novel studies on cell volume regulation in marine teleosteans

Influence of oil exposure on the physiology and ecology of the common sole Solea solea: Experimental and field approaches

International audienceEvaluating the ecological impact of an oil spill is a complex issue requiring coherently articulated examination of the sequence of interactions that link the cell, where contaminants exert their effects, to the ecosystem, where interactions with human activities arise. This sequence of interactions traverses the frontiers between scientific disciplines (chemistry, toxicology, physiology, and fisheries ecology). Using the common sole (Solea solea L.) as a model species for the coastal habitats polluted by the "Erika" oil spill, our research project attempted to define indices of functional integrity that characterised the consequences of fuel exposure at the different biological levels. The coupling of field observations with experimental laboratory work revealed how functional alterations which are readily observable within individuals and their organs are progressively obscured as investigation progresses towards more complex organisational levels. Some of the approaches and indices are proposed as instruments for evaluating the impact of contamination by hydrocarbons. Key words: Oil spill / Complex system approach / Common sole / Physiological ecology Résumé-Influence de l'exposition au fioul sur la physiologie et l'écologie de la sole commune Solea solea : approches expérimentales et in situ. L'évaluation des conséquences écologiques d'une marée noire est un problème complexe qui requiert un examen articulé et cohérent de la chaîne d'interactions qui relie l'échelle cellulaire, à la-quelle agit le contaminant, à l'échelle écosystémique, où se situent les interactions avec les activités humaines. Cette chaîne d'interactions traverse les frontières des disciplines scientifiques (chimie, toxicologie, physiologie, écologie ha-lieutique). En prenant la sole (Solea solea L.) comme espèce cible-espèce caractéristique des habitats côtiers pollués par l'« Erika »-le programme de recherche ECTOPHY est une première tentative de mise en place d'une approche multidisciplinaire visant à définir, valider et mettre en relation des indicateurs d'intégrité fonctionnelle caractérisant les différents niveaux biologiques. Le couplage d'observations in situ avec des expositions en milieu contrôlé a montré que des pertes de fonctionnalité évidentes et durables à l'échelle de l'individu sont masquées à l'échelle de la population. Certaines des approches (in situ ou expérimentale) et certains des indicateurs testés peuvent être proposés comme instruments utilisables dans le cadre d'évaluation d'impact de pollutions par des hydrocarbures