Consulta: subjectFacets:"Methylmercury"
Registros recuperados: 19
Data/hora: 11/06/2024 14:34:21

Studies of micronuclei and other nuclear abnormalities in red blood cells of Colossoma macropomum exposed to methylmercury
Provedor de dados: 74
Autores: 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 &lt; 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

Géochimie du mercure dans le continuum de la retenue de Petit-Saut et de l'estuaire du Sinnamary, Guyane française
Provedor de dados: 5
Autores: 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

Spatial and temporal distribution of mercury and methylmercury in bivalves from the French coastline
Provedor de dados: 5
Autores: 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

Difference of mercury bioaccumulation in red mullets from the north-western Mediterranean and Black seas
Provedor de dados: 5
Autores: Harmelin-vivien, M.; Cossa, Daniel; Crochet, Sylvette; Banaru, D.; Letourneur, Y.; Mellon-duval, Capucine.
The relationships between total mercury (Hg) concentration and stable nitrogen isotope ratio (delta N-15) were evaluated in Mullus barbatus barbatus and M. surmuletus from the Mediterranean Sea and M. barbatus ponticus from the Black Sea. Mercury concentration in fish muscle was six times higher in the two Mediterranean species than in the Black Sea one for similar sized animals. A positive correlation between Hg concentration and delta N-15 occurred in all species. Increase in Hg concentration with delta N-15 was high and similar in the two Mediterranean fishes and much lower in the Black Sea species. Since this was neither related to trophic level difference between species nor to methylmercury (MeHg) concentration differences between the north-western...
Tipo: Text
Palavras-chave: Black Sea; Mediterranean; Mullidae; Methylmercury; Trophic level; N 15.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6647.pdf

Amazonian former gold mined soils as a source of methylmercury: Evidence from a small scale watershed in French Guiana
Provedor de dados: 5
Autores: 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

Monomethylmercury sources in a tropical artificial reservoir
Provedor de dados: 5
Autores: 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 (&lt; 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

The biogeochemistry of mercury at the sediment water interface in the Thau lagoon. 1. Partition and speciation
Provedor de dados: 5
Autores: 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

Modeling the Influence of Eutrophication and Redox Conditions on Mercury Cycling at the Sediment-Water Interface in the Berre Lagoon
Provedor de dados: 5
Autores: 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

Diagenetic production, accumulation and sediment-water exchanges of methylmercury in contrasted sediment facies of Lake Titicaca (Bolivia)
Provedor de dados: 5
Autores: 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

A Michaelis–Menten type equation for describing methylmercury dependence on inorganic mercury in aquatic sediments
Provedor de dados: 5
Autores: 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

The open sea as the main source of methylmercury in the water column of the Gulf of Lions (Northwestern Mediterranean margin)
Provedor de dados: 5
Autores: 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 &lt;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

Mercury and methylmercury concentration assessment in children's hair from Manaus, Amazonas state, Brazil
Provedor de dados: 36
Autores: 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

Mercury and methylmercury in carapace of the marine turtle Caretta caretta, in northeastern Brazil and its potential for environmental monitoring
Provedor de dados: 42
Autores: RODRIGUEZ,CÉSAR AUGUSTO B.; BEZERRA,MOISES F.; REZENDE,CARLOS EDUARDO DE; BASTOS,WANDERLEY R.; LACERDA,LUIZ D. DE.
Abstract: The present work tests the use of carapace fragments of the marine turtle Caretta caretta as a tool for environmental biomonitoring of mercury (Hg) and to evaluate the influence of biological and ecological factors in Hg concentrations. Samples of carapace fragments were obtained during the nesting season of 2012 and 2016 and were analyzed for their total-Hg and methyl-Hg concentrations and the isotopic composition of carbon and nitrogen (δ15N and δ13C). Seventy-six females were sampled, with an average size of 87.1 to 107 cm of curved carapace length (CCL). The results showed a wide variation in total Hg concentrations (3.3 – 1,672 ng g-1) and low concentrations of methyl-Hg, not showing any pattern of accumulation among the individuals. The...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Caretta caretta; Mercury; Carapace; Methylmercury; Stable isotopes.
Ano: 2019
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652019000300402

Cytotoxicity and genotoxicity of low doses of mercury chloride and methylmercury chloride on human lymphocytes in vitro
Provedor de dados: 56
Autores: Silva-Pereira,L.C.; Cardoso,P.C.S.; Leite,D.S.; Bahia,M.O.; Bastos,W.R.; Smith,M.A.C.; Burbano,R.R.
Mercury is a xenobiotic metal that is a highly deleterious environmental pollutant. The biotransformation of mercury chloride (HgCl2) into methylmercury chloride (CH3HgCl) in aquatic environments is well-known and humans are exposed by consumption of contaminated fish, shellfish and algae. The objective of the present study was to determine the changes induced in vitro by two mercury compounds (HgCl2 and CH3HgCl) in cultured human lymphocytes. Short-term human leukocyte cultures from 10 healthy donors (5 females and 5 males) were set-up by adding drops of whole blood in complete medium. Cultures were separately and simultaneously treated with low doses (0.1 to 1000 µg/l) of HgCl2 and CH3HgCl and incubated at 37ºC for 48 h. Genotoxicity was assessed by...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Methylmercury; Cytotoxicity; Genotoxicity; Mitotic index; Human lymphocytes; Chromosome aberrations.
Ano: 2005
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2005000600012

Methylmercury inhibits prolactin release in a cell line of pituitary origin
Provedor de dados: 56
Autores: 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

Comparative effects of organic and inorganic mercury on in vivo dopamine release in freely moving rats
Provedor de dados: 56
Autores: 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

Methylmercury intoxication activates nitric oxide synthase in chick retinal cell culture
Provedor de dados: 56
Autores: 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

Losses of immunoreactive parvalbumin amacrine and immunoreactive alphaprotein kinase C bipolar cells caused by methylmercury chloride intoxication in the retina of the tropical fish Hoplias malabaricus
Provedor de dados: 56
Autores: 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

Protective effects of organoselenium compounds against methylmercury-induced oxidative stress in mouse brain mitochondrial-enriched fractions
Provedor de dados: 56
Autores: 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