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Effet de la pollution urbaine et industrielle sur le système endocrinien : évaluation des conséquences sur la reproduction de "Ruditapes decusatus" issue du golfe de Gabès (Tunisie)

Abstract : Our study aimed to assess the presence of endocrine disrupting compounds in the Gulf of Gabes area (Tunisia), their effects on the reproductive potential of the marine bivalve, Ruditapes decussatus as well as elucidating their mechanisms of action. To achieve these goals, several methodologies have been deployed, such as laboratory in vivo exposures (to urban or industrial effluents, estradiol), and in situ sampling to assess the risk of such substances on this ecosystem by using a multiparametric approach based on different levels of biological organization in clams (from biochemical level to the population level). We have demonstrated the presence of reprotoxic compounds along the south-eastern coast of Tunisia. The results revealed, a strong correlation between chemical contamination (cadmium, estrogenic and androgenic activities in sediment) and some reproductive parameters (oocyte diameter, vitellogénine and glycogen levels) and, a particular site (El hofra) that differs from all the other studied sites in this polluted context. Clams from this station seem to suffer from endocrine disruption probably resulting from a synergistic effect between both cadmium contamination and the presence of chemicals acting as estrogens and androgens in the environment. In parallel to this in situ study, three laboratory experiments were performed. The results showed that exposure to a mixture of chemical compounds released by the Sfax wastewater treatment plant had an adverse impact on the reproductive potential of R. decussatus, by inducing vitellogenin synthesis and stimulating reproduction in both sexes. Results of the exposure of organisms to 17β-estradiol alone, revealed that the estrogenic compound could contribute to the observed effects on the reproductive cycle of the test animals in the previous experiment. This natural hormone has induced deleterious effects and may play a role in the physiology of the clam. To study its mechanism of action via estrogen receptors, a partial cDNA of the gene was isolated and characterized from the clam R. decussatus. However, analysis of the transcriptional response did not show a significant change in the gene expression in males as well as in females following exposure to estrogens (17β-estradiol, urban and industrial effluents).
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Submitted on : Wednesday, March 28, 2018 - 3:05:08 PM
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  • HAL Id : tel-01745755, version 1

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Sawssan Mezghani-Chaari. Effet de la pollution urbaine et industrielle sur le système endocrinien : évaluation des conséquences sur la reproduction de "Ruditapes decusatus" issue du golfe de Gabès (Tunisie). Ecotoxicologie. Normandie Université; Université de Sfax (Tunisie), 2017. Français. ⟨NNT : 2017NORMLH25⟩. ⟨tel-01745755⟩

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