Toxicocinétique, toxicité chimique et radiologique de l'uranium chez le poisson zèbre (Danio rerio)

This thesis explores the toxicokinetic and toxicologic aspects of uranium in fish. Uranium appears to be highly bioaccumulated and bioconcentrated in fish. It spreads all through the whole organism. Nevertheless, its distribution is heterogeneous (gills and liver being the main sites of accumulation).From a toxicologic point of view, we notice perturbations of the antioxidant system (inhibitions of hepatic SOD, CAT and GPx activities; depletion of total GSH) and of the cholinergic system (inhibition/over-activation of brain AChE). Genotoxic effects also appear in red blood cells, hepatocytes and gonadic cells. The kinetics of these biochemical perturbations depend on the radiological activity of uranium, responses appearing earlier with increasing delivered activity. Histological effects (differing in types depending on delivered radiological activity) are also observed (in gills and muscles).Ce travail de thèse a visé à étudier les paramètres toxicocinétiques et toxicologiques de l'uranium chez le poisson. Il apparaît que l'uranium est hautement bioaccumulé et bioconcentré par les poissons. Sa répartition, bien que généralisée à l'ensemble de l'organisme, est néanmoins très hétérogène (branchies et foie constituant des sites majeurs d'accumulation). On note une perturbation du système antioxydant hépatique (inhibition des activités SOD, CAT et GPx ; déplétion du GSHtot) et du système cholinergique cérébral (inhibition/suractivation de l'AChE). Des atteintes génotoxiques surviennent également au niveau sanguin, hépatique et gonadique. L'activité radiologique de l'uranium influe sur les cinétiques d'apparition de ces perturbations biochimiques, celles-ci apparaissant d'autant plus précocement que l'activité délivrée est importante. Des atteintes histologiques (de différentes natures selon l'activité radiologique mise en jeu) sont également constatées (branchies, muscle)

Toxicocinétique, toxicité chimique et radiologique de l'uranium chez le poisson zèbre (Danio rerio)

Ce travail de thèse a visé à étudier les paramètres toxicocinétiques et toxicologiques de l'uranium chez le poisson. Il apparaît que l uranium est hautement bioaccumulé et bioconcentré par les poissons. Sa répartition, bien que généralisée à l'ensemble de l'organisme, est néanmoins très hétérogène (branchies et foie constituant des sites majeurs d'accumulation). On note une perturbation du système antioxydant hépatique (inhibition des activités SOD, CAT et GPx ; déplétion du GSHtot) et du système cholinergique cérébral (inhibition/suractivation de l AChE). Des atteintes génotoxiques surviennent également au niveau sanguin, hépatique et gonadique. L'activité radiologique de l'uranium influe sur les cinétiques d apparition de ces perturbations biochimiques, celles-ci apparaissant d'autant plus précocement que l'activité délivrée est importante. Des atteintes histologiques (de différentes natures selon l activité radiologique mise en jeu) sont également constatées (branchies, muscle)This thesis explores the toxicokinetic and toxicologic aspects of uranium in fish. Uranium appears to be highly bioaccumulated and bioconcentrated in fish. It spreads all through the whole organism. Nevertheless, its distribution is heterogeneous (gills and liver being the main sites of accumulation).From a toxicologic point of view, we notice perturbations of the antioxidant system (inhibitions of hepatic SOD, CAT and GPx activities; depletion of total GSH) and of the cholinergic system (inhibition/over-activation of brain AChE). Genotoxic effects also appear in red blood cells, hepatocytes and gonadic cells. The kinetics of these biochemical perturbations depend on the radiological activity of uranium, responses appearing earlier with increasing delivered activity. Histological effects (differing in types depending on delivered radiological activity) are also observed (in gills and muscles)METZ-SCD (574632105) / SudocSudocFranceF

Ultrastructural effects on gill, muscle, and gonadal tissues induced in zebrafish (Danio rerio) by a waterborne uranium exposure

International audienceExperiments on adult zebrafish (Danio rerio) were conducted to assess histopathological effects induced on gill, muscle, and gonadal tissues after waterborne uranium exposure. Although histopathology is often employed as a tool for the detection and assessment of xenobiotic-mediated effects in aquatic organisms, few studies have been dedicated to the investigation of histopathological consequences of uranium exposure in fish. Results showed that gill tissue architecture was markedly disrupted. Major symptoms were alterations of the secondary lamellae epithelium (from extensive oedema to desquamation), hyperplasia of chloride cells, and breakdown of the pillar cell system. Muscle histology was also affected. Degeneration and disorganization of myofibrillar sarcomeric pattern as well as abnormal localization of mitochondria within muscle and altered endomysial sheaths were observed. Morphological alterations of spermatozoa within the gonadal tissue were also noticed. This study demonstrated that uranium exposure induced a variety of histological impairments in fish, supporting environmental concerns when uranium contaminates aquatic systems. (C) 2010 Elsevier B.V. All rights reserved

Uranium bioaccumulation and biological disorders induced in zebrafish (Danio rerio) after a depleted uranium waterborne exposure

International audienceBecause of its toxicity and its ubiquity within aquatic compartments, uranium (U) represents a significant hazard to aquatic species such as fish. In a previous study, we investigated some biological responses in zebrafish either exposed to depleted or to enriched U (i.e., to different radiological activities). However, results required further experiments to better understand biological responses. Moreover, we failed to clearly demonstrate a significant relationship between biological effects and U radiological activity. We therefore chose to herein examine U bioaccumulation and induced effects in zebrafish according to a chemical dose-response approach. Results showed that U is highly bioconcentrated in fish, according to a time- and concentration-dependent model. Additionally, hepatic antioxidant defenses, red blood cells DNA integrity and brain acetylcholinesterase activity were found to be significantly altered. Generally, the higher the U concentration, the sooner and/or the greater the effect, suggesting a close relationship between accumulation and effect