Développement de marqueurs de neurotoxicité et de perturbations endocrines chez l'amphipode d'eau douce Gammarus fossarum

Abstract : The aim of this works was to develop specific biomarkers of neurotoxicity (cholinesterase activity) and endocrine disruptions linked to reproduction (vitellogenine synthesis) in freshwater amphipod Gammarus fossarum. G. fossarum owns only an isoforme of cholinesterase of type acetylcholinesterase (AChE). Biotic factors have been shown as the main source of natural variability of the activity AChE in this species. Therefore, the selection of organisms with male phenotype and a body-weight of 15-20 mg allowed to propose a methodology of reliable and strong dosage. A reference value and a threshold value were described. Our works on the AChE, also demonstrated that there is no relation between the inhibition of this enzymatic activity and the mortality. On the other hand, a direct relation was observed between the activity AChE and behaviours. Finally, the coupled use of in situ bioassays and measure of the activity AChE showed to be a relevant tool for the environmental assessment of anti-ChE compound impact. The description of the physiological processes, bound to the reproduction cycle of females (moult cycle, oocyte growth and embryonic development), brought bases for the development of the Vtg gene expression as biomarker. It also allowed to develop a robust and reproducible reprotoxicity-test displaying a very weak variability of the basic values observed in the non-impacted organisms. Females present an important rise of the Vtg synthesis during their reproduction cycle, corresponding with the implementation of the secondary vitellogenesis process. The induction of the Vtg gene expression was observed in males exposed in laboratory to model endocrine disrupters and in organisms exposed in situ, in areas subjected to an anthropological pressure
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Benoît Xuereb. Développement de marqueurs de neurotoxicité et de perturbations endocrines chez l'amphipode d'eau douce Gammarus fossarum. Ecologie, Environnement. Université Paul Verlaine - Metz, 2009. Français. ⟨NNT : 2009METZ057S⟩. ⟨tel-01751328⟩

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