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La présente Ligne Directrice décrit un essai permettant d’évaluer les effets sur les premiers stades de vie et les conséquences néfastes possibles de produits chimiques potentiellement perturbateurs endocriniens (ex. oestrogènes, androgènes et inhibiteurs de la stéroïdogenèse) sur le développement sexuel des poissons. Dans l’essai, les poissons sont exposés, de l'œuf nouvellement fécondé à l'achèvement de la différenciation sexuelle vers 60 jours après la ponte, à au moins trois concentrations de la substance d'essai dissoute dans de l'eau. A chaque niveau de traitement et dans le(s) témoin(s), il est recommandé d’utiliser au moins quatre réplicats. A la fin de l’essai, deux effets principaux sont mesurés sur chaque poisson: la concentration de vitellogénine à partir d’échantillons biologiques de tête et de queue ou à partir du sang, et la proportion de mâles, femelles, hermaphrodites et de poissons non sexuellement différenciés, à partir de l’examen histologique des gonades. Pour les espèces de poissons possédant un marqueur génétique sexuel, le sexe génétique est identifié chez chaque individu pour déterminer si une réversion sexuelle a eu lieu. La combinaison des deux effets endocriniens principaux, la concentration de vitellogénine et le ratio phénotypique mâles/femelles (et éventuellement le sexe génotypique) permet à l’essai d’indiquer le mode d’action de la substance testée.

Chemical tests and reagents --- Chemical reagents --- Reagents, Chemical --- Indicators and test-papers

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This Test Guideline describes an in vitro screen for chemical effects on steroidogenesis, specifically the production of 17ß-estradiol (E2) and testosterone (T). The human H295R adreno-carcinoma cell line, used for the assay, expresses genes that encode for all the key enzymes for steroidogenesis. After an acclimation period of 24 h in multi-well plates, cells are exposed for 48 h to seven concentrations of the test chemical in at least triplicate. Solvent and a known inhibitor and inducer of hormone production are run at a fixed concentration as negative and positive controls. At the end of the exposure period, cell viability in each well is analyzed. Concentrations of hormones in the medium can be measured using a variety of methods including commercially available hormone measurement kits and/or instrumental techniques such as liquid chromatography-mass spectrometry. Data are expressed as fold change relative to the solvent control and the Lowest-Observed-Effect-Concentration. If the assay is negative, the highest concentration tested is reported as the No-Observed-Effect-Concentration.

Chemical tests and reagents --- Chemical reagents --- Reagents, Chemical --- Indicators and test-papers

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The purpose of this test is to determine the effects of a substance on the growth of freshwater microalgae and/or cyanobacteria. Exponentially growing test organisms are exposed to the test substance in batch cultures over a period of normally 72 hours. The system response is the reduction of growth in a series of algal cultures exposed to, at least, five concentrations of a test substance. Three replicates at each test concentration should be used. The response is evaluated as a function of the exposure concentration in comparison with the average growth of control cultures. The cultures are allowed unrestricted exponential growth under nutrient sufficient conditions (two alternative growth media: the OECD and the AAP) and continuous fluorescent illumination. Growth and growth inhibition are quantified from measurements of the algal biomass as a function of time. The limit test corresponds to one dose level of 100 mg/L. This study includes: the determination, at least daily, of the algal biomass; the measure of the pH (at the beginning and at the end); microscopic observation. This Test Guideline describes two response variables: average specific growth rate, and yield.  

Environment --- Chemical tests and reagents --- Freshwater algae --- Cyanobacteria --- Bacteria, Blue-green --- Blue-green algae --- Blue-green bacteria --- Blue-greens (Microorganisms) --- Cryptophyceae --- Cyanochloronta --- Cyanophyceae --- Cyanophycota --- Cyanophyta --- Myxophyceae --- Myxophyta --- Phycochromophyceae --- Schizophyceae --- Prokaryotes --- Algae --- Freshwater phytoplankton --- Chemical reagents --- Reagents, Chemical --- Indicators and test-papers --- Toxicology --- Standards.