Effets de contaminations d'embryons et d'adultes de poissons zèbres (Danio rerio) par des PCB et des HAP

Abstract : Aquatic environments are ultimate reservoir for many persistent organic pollutants, including polychlorinatedbiphenyls (PCBs, bioaccumulative compounds) and polycyclic aromatic hydrocarbons (PAHs, compoundsaccumulated in the sediment and metabolized by vertebrates). Fish can be exposed to these pollutants at different life stages which can alter their functional integrity. The objectives of this PhD were to assess physiological alterations following exposure to mixtures representative of environmental situations. Thus, on the one hand,juvenile and adult zebrafish were exposed through the trophic pathway to PCB mixture representative of European Estuaries. The results showed that bioaccumulation varied with the congeners as well as transfer to eggs and for the latter, the level of chlorination is decisive. Impaired reproduction characterized by a reduction in the rate of fertilization and the appearance of a massive follicular atresia were shown. This work could be completed 1) at the molecular level to better understand the underlying mechanisms including endocrine disruptive activity and 2) by the evaluation of effects at the population level by a modelling approach. On the other hand, embryos were exposed for 96 h to sediment spiked with individual PAHs. The obtained phenotypes were consistent with the effects described for these PAHs and thus validated the exposure process. This procedure could be used to assess the toxicity of natural sediment after extraction of the aromatic fraction as well as to assess the toxicity of hydrophobic molecules. To be reliable tests, it remains essential to identify early markers of late effects to avoid under estimating the toxicity of a compound.
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Tarek Daouk. Effets de contaminations d'embryons et d'adultes de poissons zèbres (Danio rerio) par des PCB et des HAP. Sciences agricoles. Université de La Rochelle, 2011. Français. ⟨NNT : 2011LAROS346⟩. ⟨tel-00753036⟩

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