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Specific Pathways of Dietary Methylmercury and Inorganic Mercury Determined by Mercury Speciation and Isotopic Composition in Zebrafish (Danio rerio)

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journal contribution
posted on 03.11.2015, 00:00 by Caiyan Feng, Zoyne Pedrero, Sophie Gentès, Julien Barre, Marina Renedo, Emmanuel Tessier, Sylvain Berail, Régine Maury-Brachet, Nathalie Mesmer-Dudons, Magalie Baudrimont, Alexia Legeay, Laurence Maurice, Patrice Gonzalez, David Amouroux
An original approach is proposed to investigate inorganic (iHg) and methylmercury (MeHg) trophic transfer and fate in a model fish, Danio rerio, by combining natural isotopic fractionation and speciation. Animals were exposed to three different dietary conditions: (1) 50 ng Hg g–1, 80% as MeHg; (2) diet enriched in MeHg 10 000 ng Hg g–1, 95% as MeHg, and (3) diet enriched in iHg 10 000 ng Hg g–1, 99% as iHg. Harvesting was carried out after 0, 7, 25, and 62 days. Time-dependent Hg species distribution and isotopic fractionation in fish organs (muscle, brain, liver) and feces, exhibited different patterns, as a consequence of their dissimilar metabolization. The rapid isotopic re-equilibration to the new MeHg-food source reflects its high bioaccumulation rate. Relevant aspects related to Hg excretion are also described. This study confirms Hg isotopic fractionation as a powerful tool to investigate biological processes, although its deconvolution and fully understanding is still a challenge.