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| Registros recuperados: 19 | |
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| Cossa, Daniel; Garnier, Cedric; Buscail, Roselyne; Elbaz-poulichet, Francoise; Mikac, Nevenka; Patel-sorrentino, Nathalie; Tessier, Erwan; Rigaud, Sylvain; Lenoble, Veronique; Gobeil, Charles. |
| Methylation of mercury (Hg) is the crucial process that controls Hg biomagnification along the aquatic food chains. Aquatic sediments are of particular interest because they constitute an essential reservoir where inorganic divalent Hg (HgII) is methylated. Methylmercury (MeHg) concentrations in sediments mainly result from the balance between methylation and demethylation reactions, two opposite natural processes primarily mediated by aquatic microorganisms. Thus, Hg availability and the activity of methylating microbial communities control the MeHg abundance in sediments. Consistently, some studies have reported a significant positive correlation between MeHg and HgII or total Hg (HgT), taken as a proxy for HgII, in aquatic sediments using... |
| Tipo: Text |
Palavras-chave: Mercury; Methylmercury; Aquatic sediment; Methylation; Demethylation. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00171/28220/26520.pdf |
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| Guedron, Stephane; Grimaldi, Michel; Grimaldi, Catherine; Cossa, Daniel; Tisserand, Delphine; Charlet, Laurent. |
| Total mercury (HgT) and monomethylmercury (MMHg) were investigated in a tropical head watershed (1 km(2)) of French Guiana. The watershed includes a pristine area on the hill slopes and a former gold mined flat in the bottomland. Concentrations of dissolved and particulate HgT and MMHg were measured in rain, throughfall, soil water and at three points along the stream. Samples were taken in-between and during 14 storm events at the beginning and middle of the 2005 and 2006 rainy seasons. Dissolved and particulate HgT concentrations in the stream slightly increased downstream, while dissolved and particulate MMHg concentrations were low at the pristine sub-watershed outlet (median = 0.006 ng L-1 and 1.84 ng g(-1), respectively) and sharply increased at the... |
| Tipo: Text |
Palavras-chave: Mercury; Methylmercury; Tropical watershed; Gold placers; Stream water; Oxisols; Hydromorphic soils. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00035/14628/12134.pdf |
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| Faro,L.R.F.; Rodrigues,K.J.A.; Santana,M.B.; Vidal,L.; Alfonso,M.; Durán,R.. |
| The present study was carried out in order to compare the effects of administration of organic (methylmercury, MeHg) and inorganic (mercury chloride, HgCl 2 ) forms of mercury on in vivo dopamine (DA) release from rat striatum. Experiments were performed in conscious and freely moving female adult Sprague-Dawley (230-280 g) rats using brain microdialysis coupled to HPLC with electrochemical detection. Perfusion of different concentrations of MeHg or HgCl 2 (2 µL/min for 1 h, N = 5-7/group) into the striatum produced significant increases in the levels of DA. Infusion of 40 µM, 400 µM, or 4 mM MeHg increased DA levels to 907 ± 31, 2324 ± 156, and 9032 ± 70% of basal levels, respectively. The same concentrations of HgCl 2 increased DA levels to 1240 ± 66,... |
| Tipo: Info:eu-repo/semantics/other |
Palavras-chave: Methylmercury; Mercury chloride; Dopamine release in vivo; Microdialysis; Mercury determination; Striatum. |
| Ano: 2007 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2007001000009 |
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| Guédron, S.; Audry, S.; Acha, D.; Bouchet, S.; Point, D.; Condom, T.; Heredia, C.; Campillo, S.; Baya, A.; Groleau, A.; Amice, Erwan; Amouroux, D.. |
| Monomethylmercury (MMHg) concentrations in aquatic biota from Lake Titicaca are elevated although the mercury (Hg) contamination level of the lake is low. The contribution of sediments to the lake MMHg pool remained however unclear. In this work, seven cores representative of the contrasted sediments and aquatic ecotopes of Lake Titicaca were sliced and analyzed for Hg and redox-sensitive elements (Mn, Fe, N and S) speciation in pore-water (PW) and sediment to document early diagenetic processes responsible for MMHg production and accumulation in PW during organic matter (OM) oxidation. The highest MMHg concentrations (up to 12.2 ng L−1 and 90% of THg) were found in subsurface PWs of the carbonate-rich sediments which cover 75% of the small basin and 20%... |
| Tipo: Text |
Palavras-chave: Methylmercury; Lake sediment; Early diagenesis; High altitude ecosystem; Diffusive fluxes. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00615/72735/71843.pdf |
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| Muresan Paslaru, Bogdan. |
| The mercury cycle was explored in the Petit-Saut reservoir / Sinnamary Estuary continuum in French Guiana. Main processes involve (i) photo-induced reduction, (ii) adsorption and desorption at the particle surfaces, (iii) methylating bacterial activity, (iv) precipitation and dissolution of iron oxyhydroxides and sulfides. Sources of mercury to the Petit-Saut reservoir consist of the partly impacted river-tributaries, the atmospheric deposition and the flooded soils or vegetation. Once into the reservoir, divalent mercury undergoes a large spectrum of transformations including speciation and phase changes. We, here, probe these processes and demonstrate that the Petit-Saut reservoir behaves as a privileged site for atmospheric recycling and in situ... |
| Tipo: Text |
Palavras-chave: Atmosphere; Estuary; Reservoir; French Guiana; Methylmercury; Mercury; Atmosphère; Estuaire; Retenue; Guyane française; Methylmercure; Mercure. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/these-1508.pdf |
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| Bonci,D.M.O.; Lima,S.M.A. de; Grötzner,S.R.; Oliveira Ribeiro,C.A.; Hamassaki,D.E.; Ventura,D.F.. |
| To quantify the effects of methylmercury (MeHg) on amacrine and on ON-bipolar cells in the retina, experiments were performed in MeHg-exposed groups of adult trahiras (Hoplias malabaricus) at two dose levels (2 and 6 µg/g, ip). The retinas of test and control groups were processed by mouse anti-parvalbumin and rabbit anti-alphaprotein kinase C (alphaPKC) immunocytochemistry. Morphology and soma location in the inner nuclear layer were used to identify immunoreactive parvalbumin (PV-IR) and alphaPKC (alphaPKC-IR) in wholemount preparations. Cell density, topography and isodensity maps were estimated using confocal images. PV-IR was detected in amacrine cells in the inner nuclear layer and in displaced amacrine cells from the ganglion cell layer, and... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Methylmercury; Retina; Hoplias malabaricus; Amacrine cells; Displaced amacrine cells; ON-bipolar cells. |
| Ano: 2006 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2006000300011 |
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| Farias,Luciana A.; Fávaro,Déborah I. T.; Pessoa,Artemiza; Aguiar,Jaime P. L.; Yuyama,Lúcia K. O.. |
| The present study evaluated Hg and MeHg content in hair samples of 201 children 2 to 7 years old, living in six neighborhoods of the city of Manaus, Amazonas State, Brazil. In general, the total Hg and MeHg median ranges in hair were similar (0.91 to 1.71 mg kg-1) except for the São Jose neighborhood, which was lower (0.16 mg kg-1). De spite the fact that the Manaus population consumes fish as part of the normal dietary intake, the Hg hair levels were below the level for an adult population not exposed to mercury (2.0 mg kg-1). These data were compared to demographic, socioeconomic information and eating habits of the families that took part in the study. The results were also compared to other published data from the Amazon region, other regions of Brazil... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Mercury; Methylmercury; Children's hair; Amazon region. |
| Ano: 2012 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0044-59672012000200015 |
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| Maués,L.A.L.; Macchi,B.M.; Crespo-López,M.E.; Nasciutti,L.E.; Picanço-Diniz,D.L.W.; Antunes-Rodrigues,J.; Nascimento,J.L.M. do. |
| Heavy metals, such as methylmercury, are key environmental pollutants that easily reach human beings by bioaccumulation through the food chain. Several reports have demonstrated that endocrine organs, and especially the pituitary gland, are potential targets for mercury accumulation; however, the effects on the regulation of hormonal release are unclear. It has been suggested that serum prolactin could represent a biomarker of heavy metal exposure. The aim of this study was to evaluate the effect of methylmercury on prolactin release and the role of the nitrergic system using prolactin secretory cells (the mammosomatotroph cell line, GH3B6). Exposure to methylmercury (0-100 μM) was cytotoxic in a time- and concentration-dependent manner, with an LC50... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Mercury; Methylmercury; Prolactin; Oxidative stress; Pituitary; Nitric oxide. |
| Ano: 2015 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2015000800691 |
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| Herculano,A.M.; Crespo-López,M.E.; Lima,S.M.A.; Picanço-Diniz,D.L.W.; Nascimento,J.L.M. Do. |
| The visual system is a potential target for methylmercury (MeHg) intoxication. Nevertheless, there are few studies about the cellular mechanisms of toxicity induced by MeHg in retinal cells. Various reports have indicated a critical role for nitric oxide synthase (NOS) activation in modulating MeHg neurotoxicity in cerebellar and cortical regions. The aim of the present study is to describe the effects of MeHg on cell viability and NOS activation in chick retinal cell cultures. For this purpose, primary cultures were prepared from 7-day-old chick embryos: retinas were aseptically dissected and dissociated and cells were grown at 37ºC for 7-8 days. Cultures were exposed to MeHg (10 µM, 100 µM, and 1 mM) for 2, 4, and 6 h. Cell viability was measured by MTT... |
| Tipo: Info:eu-repo/semantics/other |
Palavras-chave: Methylmercury; Chick retinal cell culture; Nitric oxide synthase; Cell viability; Neurotoxicity. |
| Ano: 2006 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2006000300013 |
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| Pakhomova, Svetlana; Yakushev, Evgeniy; Protsenko, Elizaveta; Rigaud, Sylvain; Cossa, Daniel; Knoery, Joel; Couture, Raoul-marie; Radakovitch, Olivier; Yakubov, Shamil; Krzeminska, Dominika; Newton, Alice. |
| This study presents a specifically designed Mercury module in a coupled benthic-pelagic reactive-transport model - Bottom RedOx Model (BROM) that allows to study mercury (Hg) biogeochemistry under different conditions. This module considers the transformation of elemental mercury (Hg(0)), divalent mercury (Hg(II)) and methylmercury (MeHg). The behavior of mercury species in the model is interconnected with changes of oxygen, hydrogen sulfide, iron oxides, organic matter, and biota. We simulated the transformation and transport of Hg species in the water column and upper sediment layer under five different scenarios, combining various levels of oxygenation and trophic state in the Berre lagoon, a shallow eutrophic lagoon of the French Mediterranean coast... |
| Tipo: Text |
Palavras-chave: Mercury; Methylmercury; Biogeochemical modeling; Anoxia; Eutrophication; Lagoon; BROM. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00454/56535/58239.pdf |
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| Muresan, B; Cossa, Daniel; Richard, Sophie; Dominique, Y. |
| The distribution and speciation of mercury (Hg) in the water column, the inputs (wet deposition and tributaries) and the outputs (atmospheric evasion and outlet) of an artificial partially anoxic tropical lake (Petit-Sa-Lit reservoir, French Guiana) were investigated oil a seasonal basis in order to appraise the cycling and transformations of this metal. The total mercury (HgT) concentrations in the oxygenated epilimnetic waters averaged 5 +/- 3 pmol L-1 in the unfiltered samples (HgTUNF) and 4 +/- 2 pmol L-1 in the dissolved (HgTD) phase (< 0.45 mu m). On average, the monomethylmercury (MMHg) constituted 8%, 40%, and 18% of the HgT in the dissolved phase, tile particulate suspended matter and in tile unfiltered samples, respectively. Covariant elevated... |
| Tipo: Text |
Palavras-chave: Tropical environment; Artificial reservoir; Methylmercury; Mercury. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-4198.pdf |
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| Meinerz,D.F.; de Paula,M.T.; Comparsi,B.; Silva,M.U.; Schmitz,A.E.; Braga,H.C.; Taube,P.S.; Braga,A.L.; Rocha,J.B.T.; Dafre,A.L.; Farina,M.; Franco,J.L.; Posser,T.. |
| We evaluated the potential neuroprotective effect of 1-100 µM of four organoselenium compounds: diphenyl diselenide, 3’3-ditri-fluoromethyldiphenyl diselenide, p-methoxy-diphenyl diselenide, and p-chloro-diphenyl diselenide, against methylmercury-induced mitochondrial dysfunction and oxidative stress in mitochondrial-enriched fractions from adult Swiss mouse brain. Methylmercury (10-100 µM) significantly decreased mitochondrial activity, assessed by MTT reduction assay, in a dose-dependent manner, which occurred in parallel with increased glutathione oxidation, hydroperoxide formation (xylenol orange assay) and lipid peroxidation end-products (thiobarbituric acid reactive substances, TBARS). The co-incubation with diphenyl diselenide (100 µM) completely... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Methylmercury; Mitochondria; Oxidative stress; Organoselenium compounds; Diphenyl diselenide. |
| Ano: 2011 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2011001100012 |
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| Briant, Nicolas; Chouvelon, Tiphaine; Martinez, Laura; Brach-papa, Christophe; Chiffoleau, Jean-francois; Savoye, N.; Sonke, J.; Knoery, Joel. |
| Marine mercury (Hg) concentrations have been monitored in the French coastline for the last half a century using bivalves. The analyses presented in this study concerned 192 samples of bivalves (mussels: Mytilus edulis and Mytilus galloprovincialis and oysters: Crassostrea gigas and Isognomon alatus) from 77 sampling stations along the French coast and in the French Antilles sea. The goals of this study were to assess MeHg levels in various common bivalves from French coastline, and to identify possible geographic, taxonomic or temporal variations of concentrations. We show that the evolution of methylmercury (MeHg) concentrations covary with total mercury (HgT) concentrations. Moreover, in most of the study sites, HgT concentrations have not decreased... |
| Tipo: Text |
Palavras-chave: Mercury; Methylmercury; France; Bivalves; Speciation. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00353/46465/46398.pdf |
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| Rocha,Carlos Alberto Machado da; Cunha,Lorena Araújo da; Pinheiro,Raul Henrique da Silva; Bahia,Marcelo de Oliveira; Burbano,Rommel Mario Rodríguez. |
| The frequencies of micronuclei (MN) and morphological nuclear abnormalities (NA) in erythrocytes in the peripheral blood of tambaqui (Colossoma macropomum), treated with 2 mg.L-1 methylmercury (MeHg), were analyzed. Two groups (nine specimens in each) were exposed to MeHg for different periods (group A - 24 h; group B - 120 h). A third group served as negative control (group C, untreated; n = 9). Although, when compared to the control group there were no significant differences in MN frequency in the treated groups, for NA, the differences between the frequencies of group B (treated for 120 h) and the control group were extremely significant (p < 0.02), thus demonstrating the potentially adverse effects of MeHg on C. macropomum erythrocytes after... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Cytotoxicity; Genotoxicity; Methylmercury; Micronuclei assay. |
| Ano: 2011 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572011000400024 |
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| Muresan Paslaru, Bogdan; Cossa, Daniel; Jezequel, D; Prevot, F; Kerbellec, S. |
| Solid sediment, pore and epibenthic waters were collected from the Thau lagoon (France) in order to study the post depositional partition and mobility of mercury and monomethylmercury in an organic rich sediment. Total Hg (HgT) and monomethymercury (MMHg) profiles were produced in both dissolved and solid phases. The distribution of HgT in the solid appeared to be related to the historical changes in the Hg inputs into the lagoon. HgT was in equilibrium between solid and solution in the sulfidic part of the cores, with a mean log Kd of 4.9 +- 0.2. The solid appeared to be a source of HgT for pore water in the upper oxic to suboxic parts of the cores. The MMHg represented a small fraction of HgT: 3-15 % and 0.02-0.80 % in the dissolved and in the solid... |
| Tipo: Text |
Palavras-chave: Fluxes; Partition; Sediment; Lagoon; Methylmercury; Mercury. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2006/publication-2083.pdf |
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| Cossa, Daniel; De Madron, Xavier Durrieu; Schafer, Jorg; Lanceleur, Laurent; Guedron, Stephane; Buscail, Roselyne; Thomas, Bastien; Castelle, Sabine; Naudin, Jean-jacques. |
| Despite the ecologic and economical importance of coastal areas, the neurotoxic bioaccumulable monomethylmercury (MMHg) fluxes within the ocean margins and exchanges with the open sea remain unassessed. The aim of this paper is to address the questions of the abundance, distribution, production and exchanges of methylated mercury species (MeHgT), including MMHg and dimethylmercury (DMHg), in the waters, atmosphere and sediments of the Northwestern Mediterranean margin including the Rhône River delta, the continental shelf and its slope (Gulf of Lions) and the adjacent open sea (North Gyre). Concentrations of MeHgT ranged from <0.02 to 0.48 pmol L−1 with highest values associated with the oxygen-deficient zone of the open sea. The methylated mercury to... |
| Tipo: Text |
Palavras-chave: Mercury; Methylmercury; Ocean margin; Coastal area; Mediterranean. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00363/47399/47477.pdf |
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| Registros recuperados: 19 | |
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