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1.
Food Chem ; 303: 125351, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31466027

RESUMO

The ability of vegetables to inhibit methylmercury absorption was verified, with the aim of lowering the mercury level in cultured fish. Vegetable juice was obtained from 17 varieties of commercial vegetables. A test solution containing 1 µg/g methylmercury, 10% vegetable juice, and 90% physiological saline (v/v) was introduced into the intestinal tract of red sea bream, and the mercury absorption rate was measured. A significant inhibitory effect was observed for green pepper, burdock, and red shiso, mainly in the fraction with a molecular weight >3 kDa. Frozen storage for one month did not affect the inhibitory effect of green pepper; however, the inhibitory effect of frozen burdock and red shiso were destroyed after one week and one month, respectively. During one month of storage in frozen conditions, the inhibitory effect of green pepper was observed in fractions larger than 100 kDa. Molecular weight distribution of the effective fraction varied among the vegetables.


Assuntos
Sucos de Frutas e Vegetais/análise , Absorção Intestinal/efeitos dos fármacos , Intestinos/efeitos dos fármacos , Mercúrio/metabolismo , Dourada , Animais , Mercúrio/química , Mercúrio/toxicidade , Alimentos Marinhos/análise
2.
Environ Monit Assess ; 191(9): 566, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31418123

RESUMO

Mercury (Hg) is a pollutant that poses a global threat, and it was listed as one of the ten leading 'chemicals of concern' by the World Health Organization in 2017. The review aims to summarize the sources of Hg, its combined effects on the ecosystem, and its remediation in the environment. The flow of Hg from coal to fly ash (FA), soil, and plants has become a serious concern. Hg chemically binds to sulphur-containing components in coal during coal formation. Coal combustion in thermal power plants is the major anthropogenic source of Hg in the environment. Hg is taken up by plant roots from contaminated soil and transferred to the stem and aerial parts. Through bioaccumulation in the plant system, Hg moves into the food chain, resulting in potential health and ecological risks. The world average Hg concentrations reported in coal and FA are 0.01-1 and 0.62 mg/kg, respectively. The mass of Hg accumulated globally in the soil is estimated to be 250-1000 Gg. Several techniques have been applied to remove or minimize elevated levels of Hg from FA, soil, and water (soil washing, selective catalytic reduction, wet flue gas desulphurization, stabilization, adsorption, thermal treatment, electro-remediation, and phytoremediation). Adsorbents such as activated carbon and carbon nanotubes have been used for Hg removal. The application of phytoremediation techniques has been proven as a promising approach in the removal of Hg from contaminated soil. Plant species such as Brassica juncea are potential candidates for Hg removal from soil.


Assuntos
Poluentes Ambientais/análise , Poluentes Ambientais/toxicidade , Recuperação e Remediação Ambiental/métodos , Mercúrio/análise , Mercúrio/toxicidade , Biodegradação Ambiental , Carvão Mineral/análise , Cinza de Carvão/análise , Monitoramento Ambiental/métodos , Mostardeira/crescimento & desenvolvimento , Nanotubos de Carbono/química , Centrais Elétricas , Solo/química
3.
Ecotoxicol Environ Saf ; 183: 109542, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31401333

RESUMO

Mercury (Hg) is one of the most toxic heavy metals with strong negative effects on the plant growth and functions. Salicylic acid (SA) is an important signaling molecule which confers tolerance to metal toxicities but little is known about the mechanisms of SA-mediated alleviation of Hg stress. Here, physiochemical and molecular responses of Hg-stressed lemon balm (Melissa officinalis L.) to exogenous SA were investigated to reveal SA-induced tolerance mechanisms. The CHLG gene of lemon balm which encodes chlorophyll synthase was also partly isolated and sequenced for the first time. Hg stress markedly decreased growth, relative water content (RWC) and photosynthetic pigments of the plant. However, exogenous SA significantly mitigated the toxic effects of mercury on the growth and RWC and enabled plant to maintain chlorophylls to the similar levels of unstressed plants. Hg-induced oxidative damage was also reduced following treatment with SA and treated plants showed the lower extent of lipid peroxidation which was accompanied with the higher free proline and phenolics contents and elevation of the antioxidant capacity as evidenced by DPPH radical scavenging and FRAP assays. Moreover, SA treatment resulted in up-regulation of CHLG and phenylalanine ammonia-lyase (PAL) genes as key components of chlorophyll and phenylpropanoid routes, respectively. Our results collectively indicate the ameliorative effects of exogenous SA in mercury toxicity through coordinated alternations in plant metabolic processes which provide insights to better understand mechanisms of Hg tolerance in lemon balm plant.


Assuntos
Antioxidantes/metabolismo , Poluentes Ambientais/toxicidade , Melissa/efeitos dos fármacos , Mercúrio/toxicidade , Fotossíntese/efeitos dos fármacos , Ácido Salicílico/farmacologia , Carbono-Oxigênio Ligases/genética , Carbono-Oxigênio Ligases/metabolismo , Clorofila/metabolismo , Poluentes Ambientais/metabolismo , Expressão Gênica/efeitos dos fármacos , Peroxidação de Lipídeos/efeitos dos fármacos , Melissa/crescimento & desenvolvimento , Melissa/metabolismo , Mercúrio/metabolismo , Oxirredução , Fenóis/metabolismo , Fenilalanina Amônia-Liase/genética , Fenilalanina Amônia-Liase/metabolismo
4.
Ecotoxicol Environ Saf ; 183: 109549, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31408818

RESUMO

Paspalum distichum L. was tested to evaluate its ability to phytoremediate mercury (Hg) contaminated soil over a 60-d period by analysis of the total Hg concentrations in roots and leaves. Hg concentration in Hg-contamination soil decreased by 70.0 µg g-1 after 60 day of grass cultivation and Hg was readily taken up by the roots (4.51 ±â€¯1.90 µg g-1) rather than the leaves (0.35 ±â€¯0.02 µg g-1). In addition, a comparative proteomic study was performed to unravel the protein expression involved in the Hg stress response in P. distichum L. A total of 49 proteins were classified as differentially proteins in the roots by the 'top three' proteomic analysis, of which 32 were up-regulated and 17 down-regulated in response to Hg stress. These changed proteins were classified by gene ontology analysis into five complex molecular functions involving photosynthesis and energy metabolism (31%), oxidative stress (14%), protein folding (16%), sulfur compound metabolism (10%), metal binding, and ion transport (29%). Moreover, the protein expression patterns were consistent with the metabolism pathway results. Overall, the results contribute to our understanding of the molecular mechanisms of the Hg response in P. distichum and we propose a theoretical basis for the phytoremediation of Hg-contaminated soils.


Assuntos
Mercúrio/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Paspalum/efeitos dos fármacos , Proteínas de Plantas/metabolismo , Poluentes do Solo/toxicidade , Biodegradação Ambiental , Regulação para Baixo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Mercúrio/metabolismo , Estresse Oxidativo/genética , Paspalum/genética , Paspalum/metabolismo , Fotossíntese/efeitos dos fármacos , Fotossíntese/genética , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Proteômica , Poluentes do Solo/metabolismo , Regulação para Cima
5.
Chemistry ; 25(55): 12810-12819, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31298434

RESUMO

The Hg-C bond of MeHgCl, a ubiquitous environmental toxicant, is notoriously inert and exceedingly difficult to cleave. The cleavage of the Hg-C bond of MeHgCl at low temperature, therefore, is of significant importance for human health. Among various bis(imidazole)-2-selones Ln Se (n=1-4, or 6), the three-spacer L3 Se shows extraordinarily high reactivity in the degradation of various mercury alkyls including MeHgCl because of its unique ability to coordinate through κ2 -fashion, in which both the Se atoms simultaneously attack the Hg center of mercury alkyls for facile Hg-C bond cleavage. It has the highest softness (σ) parameter and the lowest HOMO(Ln Se)-LUMO(MeHgX) energy gap and, thus, L3 Se is the most reactive among Ln Se towards MeHgX (X=Cl or I). L3 Se is highly efficient, more than L1 Se, in restoring the activity of antioxidant enzyme glutathione reductase (GR) that is completely inhibited by MeHgCl; 80 % GR activity is recovered by L3 Se relative to 50 % by L1 Se. It shows an excellent cytoprotective effect in liver cells against MeHgCl-induced oxidative stress by protecting vital antioxidant enzymes from inhibition caused by MeHgCl and, thus, does not allow to increase the intracellular reactive oxygen species (ROS) levels. Furthermore, it protects the mitochondrial membrane potential (ΔΨm ) from perturbation by MeHgCl. Major Hg-responsive genes analyses demonstrate that L3 Se plays a significant role in MeHg+ detoxification in liver cells.


Assuntos
Antioxidantes/farmacologia , Glutationa Redutase/metabolismo , Substâncias Perigosas/análise , Mercúrio/análise , Mercúrio/toxicidade , Compostos Organometálicos/química , Espécies Reativas de Oxigênio/metabolismo , Selênio/química , Antioxidantes/química , Citoproteção , Glutationa Redutase/química , Substâncias Perigosas/química , Humanos , Mercúrio/química , Espécies Reativas de Oxigênio/química , Selênio/análise
6.
Aquat Toxicol ; 214: 105259, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31352075

RESUMO

The potential of using gene expression signature as a biomarker of toxicants exposure was explored in the microalga Chlamydomonas reinhardtii exposed 2 h to mercury (Hg) as inorganic mercury (IHg) and methyl mercury (MeHg) in presence of copper (Cu) and Suwannee River Humic Acid (SRHA). Total cellular Hg (THg = IHg + MeHg) decreased in presence of SRHA for 0.7 nM IHg and 0.4 nM MeHg, but increased for 70 nM IHg exposure. In mixtures of IHg + MeHg and (IHg or MeHg) + Cu, SRHA decreased THg uptake, except for 0.7 nM IHg + 0.4 nM MeHg which was unchanged (p-value>0.05). In the absence of SRHA, 0.5 µM Cu strongly decreased intracellular THg concentration for 70 nM IHg, while it had no effect for 0.7 nM IHg and 0.4 nM MeHg. The expression of single transcripts was not correlated with measured THg uptake, but a subset of 60 transcripts showed signatures specific to the exposed metal(s) and was congruent with exposure concentration. Notably, the range of fold change values of this subset correlated with THg bioaccumulation with a two-slope pattern in line with [THg]intra/[THg]med ratios. Gene expression signature seems a promising approach to complement chemical analyses to assess bioavailability of toxicants in presence of other metals and organic matter.


Assuntos
Chlamydomonas reinhardtii/genética , Exposição Ambiental , Perfilação da Expressão Gênica , Mercúrio/toxicidade , Compostos de Metilmercúrio/toxicidade , Animais , Disponibilidade Biológica , Cádmio/toxicidade , Chlamydomonas reinhardtii/efeitos dos fármacos , Chlamydomonas reinhardtii/metabolismo , Feminino , Substâncias Húmicas/análise , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , NAD/metabolismo , Oncorhynchus mykiss/metabolismo , Consumo de Oxigênio/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Temperatura Ambiente , Poluentes Químicos da Água/toxicidade
7.
Arch Environ Contam Toxicol ; 77(3): 421-431, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31292676

RESUMO

Mercury (Hg), one of the most toxic heavy metals, is commonly used in the gold extraction process in small-scale mining operations in many countries. Our previous field work on the impact of mining on soil nematode assemblages in a small-scale mining area in Sibutad, the Philippines, revealed no significant negative effects despite sometimes strongly elevated Hg concentrations. Using a microcosm approach, we now applied similar Hg concentrations as commonly found in these field sites (2.5, 5, and 10 mg/kg Hg) and determined their impact on nematode assemblages from a different soil with different physicochemical soil attributes. Our results demonstrate (a) limited "bottling" effects (incubation effects) after a 45-day incubation period: a nematode abundance decrease of up to 37%, but absence of significant differences in diversity and nematode assemblage composition; (b) that total nematode abundance already decreased at Hg concentrations (2.5 mg/kg), which did not yield significant impacts on other nematode assemblage descriptors, such as assemblage composition and different diversity indices; and (c) that the Hg concentrations found in the Sibutad field sites can be detrimental to soil nematode assemblages. The discrepancy between our microcosm and the field-based results is probably related to differences in physicochemical soil attributes (e.g., OM contents, soil pH), which suggests that nematode-based environmental assessments should be interpreted in a context-dependent manner.


Assuntos
Mercúrio/toxicidade , Nematoides/efeitos dos fármacos , Microbiologia do Solo , Poluentes do Solo/toxicidade , Animais , Biodiversidade , Ecotoxicologia/métodos , Mineração , Filipinas , Solo/química
8.
Ecotoxicol Environ Saf ; 182: 109440, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31336228

RESUMO

Mercury, and particularly its organic form, methylmercury (MeHg), is a ubiquitous environmental contaminant with documented dosage-dependent adverse effects on endpoints spanning many levels of biological organization. However, relatively little is known about the sublethal impacts of environmentally-relevant exposures on behavioral characteristics that may impact predator-prey relationships, and thus the potential for Hg bioaccumulation within food webs due to behavioral impairments. This study investigated the potential for dietary mercury exposure to impair two behavioral outcomes in the highly invasive rusty crayfish, Faxonius rusticus, which are expected to influence interactions with their fish predators: the tail-flip escape response and chelae pinch strength. Field-caught animals were randomly assigned to four dietary treatments with mean (±1 SE) dry-weight total Hg (THg) concentrations of 3.52 ±â€¯0.57, 114.01 ±â€¯4.05, 274.10 ±â€¯0.38, and 565.79 ±â€¯1.33 ng/g in the control, low, moderate and high exposure treatments, respectively, for 16 weeks. After initial observations, exposures began and mass and behavior were measured every two weeks. At the end of the experiment, THg concentrations in tail muscle tissue were significantly higher in the high exposure treatment than in the control and low exposure treatments (Tukey's HSD, family-wise α = 0.05). Exposure-dependent declines in survival, mass, pinch strength, or tail-flip escape response velocity were not detected within the 12- to 16-week experimental exposure period, which represents one season of the crayfish's 3-4 year lifespan. This suggests that crayfish may be relatively tolerant of dietary exposure to sublethal concentrations of mercury within a single season. Further investigation of the physiological underpinnings of this tolerance is warranted.


Assuntos
Astacoidea/fisiologia , Comportamento Animal/efeitos dos fármacos , Mercúrio/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Cyprinidae , Dieta , Exposição Dietética , Exposição Ambiental , Peixes , Cadeia Alimentar , Mercúrio/análise , Compostos de Metilmercúrio , Músculos/química , Alimentos Marinhos
11.
Life Sci ; 231: 116578, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31211996

RESUMO

AIMS: The aim of the present study is to shed light on the modulating action of selenium on two of the most crucial cellular pathways; apoptosis and autophagy and the possible interplay between them in determining the pituitary fate in the context of mercury intoxication through demonstration of the molecular, histopathological, immunohistochemical, and ultrastructural features of selenium mercury-treated adenohypophysis. METHODS: Thirty adult Sprague Dawley male albino rats were assigned into control group, mercury-treated group and mercury­selenium concomitantly-treated group. The adenohypophysis was subjected to structural, molecular and protein expression assessment of autophagy and apoptotic markers and western blotted analysis of Beclin 1 as a key cross-regulator of autophagy and apoptosis. KEY FINDINGS: Selenium treatment ameliorated the mercury-induced apoptosis detected by improvement in PCR and immunohistochemical expression of the apoptotic markers Bax, Bcl-2 and Caspase-3. Selenium also improved mercury-induced autophagic dysfunction with statistically significant improvement in western blotted levels of the autophagy markers LC3I, LC3II and Beclin1. The histopathological and ultrastructural studies strongly confirmed those findings. SIGNIFICANCE: The crosstalk between the apoptotic Bcl-2 family of proteins and the autophagic Beclin-1LC3 pathway in the context of mercury intoxication paves the way for developing novel effective treatment strategies for several mercury-induced pituitary diseases.


Assuntos
Intoxicação por Mercúrio/prevenção & controle , Mercúrio/toxicidade , Hipófise/efeitos dos fármacos , Selênio/farmacologia , Animais , Apoptose/efeitos dos fármacos , Proteínas Reguladoras de Apoptose/metabolismo , Autofagia/efeitos dos fármacos , Proteína Beclina-1/metabolismo , Caspase 3/metabolismo , Masculino , Intoxicação por Mercúrio/metabolismo , Intoxicação por Mercúrio/patologia , Hipófise/metabolismo , Hipófise/patologia , Adeno-Hipófise/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Ratos , Ratos Sprague-Dawley , Proteína X Associada a bcl-2/metabolismo
12.
Ecotoxicol Environ Saf ; 180: 535-541, 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31128551

RESUMO

The relatively low availability of toxicity data for indigenous tropical species has often been discussed. In addition, several taxonomic groups of invertebrates are understudied, such as dragonflies and ostracods. The aim of the present study was therefore to evaluate the acute toxicity of four metals (cadmium - Cd, copper - Cu, manganese - Mn, and mercury - Hg) to the tropical dragonfly nymphs of Tramea cophysa and two tropical ostracod species (Chlamydotheca sp. and Strandesia trispinosa). Toxicity data for other invertebrates were also mined to allow comparing the sensitivity of the three test species with that of other (temperate and tropical) invertebrates. The order of metal sensitivity was different for the three test species: T. cophysa: Cu > CdHg > Mn, Chlamydotheca sp.: Cd > Cu > Hg > Mn, and S. trispinosa: Cd > Hg > Cu > Mn. However, manganese was the least toxic metal tested for all three species, which is hypothesized to be due to a possible metal transfer to the cuticle of the moulting test species. The sensitivity ranking of the three test species to the metals was S. trispinosa > Chlamydotheca sp.>T. cophysa (except for Cu for which the ranking was Chlamydotheca sp.>T. cophysa > S. trispinosa). Overall, the test species are concluded to be suitable test organisms for tropical toxicity evaluations. Future studies should also evaluate the chronic toxicity and include other important metal exposure routes such as sediment and food.


Assuntos
Metais Pesados/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Cádmio/toxicidade , Cobre/toxicidade , Crustáceos/efeitos dos fármacos , Manganês/toxicidade , Mercúrio/toxicidade , Odonatos/efeitos dos fármacos
13.
Methods Mol Biol ; 1965: 7-17, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31069665

RESUMO

Mouse embryonic fibroblasts (MEFs) are commonly collected as a means to maintain the culture and growth of embryonic stem cells (ESCs). However, their utility can extend well beyond their use exclusively in ESC culture. With collection from various transgenic mouse models, use of MEFs may serve as a more simplistic means to reconstitute in vivo/in utero toxicological assessments in an in vitro format for evaluation of function of specific proteins during toxic insults. The ease of collection, rapid growth kinetics, and large-scale expansion to perform multiple, high-throughput experiments are just some of the advantages of MEF use. Here, we describe procedures for successful MEF isolation and culture. As an example of MEF utility, we use MEFs collected form wild-type (WT) and Nrf2 knockout mice. After collection, MEFs were pretreated with the Nrf2 activator, dithiol-3-thione (D3T; 10 µM) for 12 h, and then treated with either hydrogen peroxide (0-2000 µM) or mercury (0-100 µM) for another 24 h. Viability was measured via MTT assay after 24 h of treatment.


Assuntos
Embrião de Mamíferos/citologia , Fibroblastos/citologia , Peróxido de Hidrogênio/toxicidade , Mercúrio/toxicidade , Fator 2 Relacionado a NF-E2/genética , Tionas/toxicidade , Tiofenos/toxicidade , Animais , Técnicas de Cultura de Células , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Feminino , Fibroblastos/efeitos dos fármacos , Técnicas de Inativação de Genes , Camundongos , Camundongos Transgênicos , Modelos Biológicos , Testes de Toxicidade
14.
Int J Mol Sci ; 20(10)2019 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-31100949

RESUMO

Methylmercury (MeHg) causes severe damage to the central nervous system, and there is increasing evidence of the association between MeHg exposure and vascular dysfunction, hemorrhage, and edema in the brain, but not in other organs of patients with acute MeHg intoxication. These observations suggest that MeHg possibly causes blood-brain barrier (BBB) damage. MeHg penetrates the BBB into the brain parenchyma via active transport systems, mainly the l-type amino acid transporter 1, on endothelial cell membranes. Recently, exposure to mercury has significantly increased. Numerous reports suggest that long-term low-level MeHg exposure can impair endothelial function and increase the risks of cardiovascular disease. The most widely reported mechanism of MeHg toxicity is oxidative stress and related pathways, such as neuroinflammation. BBB dysfunction has been suggested by both in vitro and in vivo models of MeHg intoxication. Therapy targeted at both maintaining the BBB and suppressing oxidative stress may represent a promising therapeutic strategy for MeHg intoxication. This paper reviews studies on the relationship between MeHg exposure and vascular dysfunction, with a special emphasis on the BBB.


Assuntos
Barreira Hematoencefálica/efeitos dos fármacos , Barreira Hematoencefálica/metabolismo , Sistema Nervoso Central/efeitos dos fármacos , Sistema Nervoso Central/metabolismo , Compostos de Metilmercúrio/toxicidade , Sistemas de Transporte de Aminoácidos Básicos/efeitos dos fármacos , Animais , Transporte Biológico/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Humanos , Transportador 1 de Aminoácidos Neutros Grandes/metabolismo , Mercúrio/toxicidade , Estresse Oxidativo
15.
Environ Pollut ; 250: 944-952, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31085481

RESUMO

The Minamata Convention entered into force in 2017 with the aim to phase-out the use of mercury (Hg) in manufacturing processes such as the chlor-alkali or vinyl chloride monomer production. However, past industrial use of Hg had already resulted in extensive soil pollution, which poses a potential environmental threat. We investigated the emission of gaseous elemental mercury (Hg0) from Hg polluted soils in settlement areas in the canton of Valais, Switzerland, and its impact on local air Hg concentrations. Most soil Hg was found as soil matrix-bound divalent Hg (HgII). Elemental mercury (Hg0) was undetectable in soils, yet we observed substantial Hg0 emission (20-1392 ng m-2 h-1) from 27 soil plots contaminated with Hg (0.2-390 mg Hg kg-1). The emissions of Hg0 were calculated for 1274 parcels covering an area of 8.6 km2 of which 12% exceeded the Swiss soil remediation threshold of 2 mg Hg kg-1. The annual Hg0 emission from this area was approximately 6 kg a-1, which is almost 1% of the total atmospheric Hg emissions in Switzerland based on emission inventory estimates. Our results show a higher abundance of Hg resistance genes (merA) in soil microbial communities with increasing soil Hg concentrations, indicating that biotic reduction of HgII is likely an important pathway to form volatile Hg0 in these soils. The total soil Hg pool in the top 20 cm of the investigated area was 4288 kg; hence, if not remediated, these contaminated soils remain a long-term source of atmospheric Hg, which is prone to long-range atmospheric transport.


Assuntos
Bactérias/efeitos dos fármacos , Bactérias/genética , Monitoramento Ambiental/métodos , Mercúrio/análise , Mercúrio/toxicidade , Oxirredutases/genética , Poluentes do Solo/análise , Solo/química , Farmacorresistência Bacteriana/genética , Poluição Ambiental/análise , Indústrias , Conceitos Meteorológicos , Suíça
16.
Food Chem Toxicol ; 130: 187-198, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31078725

RESUMO

Mercury (Hg) is a potent toxicant. In the field of public health a chronic-low-level environmental Hg exposure resulting from fish consumption in general population is still being discussed. The objective of the study was to assess the influence of real Hg exposure on biomarkers of selenium (Se) status and selected biomarkers of pro-oxidant/anti-oxidant effects in healthy men (n = 67) who participated in the short-term intervention study consisting in daily fish consumption for two weeks. The analysis included Se level, Se-associated antioxidants at molecular (profile of 7 genes encoding selected proteins related to antioxidant defense) and biochemical levels (Se-dependent glutathione peroxidases activities and plasma selenoprotein P concentration). A pro-oxidant/anti-oxidant balance was explored using a biomarker of plasma lipid peroxidation and total antioxidant activity. The study revealed significant correlations (p < 0.05) between the biomarkers of exposure to Hg, Se level and Se-dependent antioxidants. Even though the risk of adverse effects of Hg for volunteers was substantially low, biomarkers of Hg altered levels of circulation selenoproteins and their genes expression. Changes in genes expression during study differed between the main enzymes involved in two systems: downregulation of thioredoxin reductase1 and upregulation of glutathione peroxidases. Hg exposure caused imbalance between the biomarkers of pro-oxidant/anti-oxidant effects.


Assuntos
Antioxidantes/metabolismo , Exposição Ambiental , Mercúrio/toxicidade , Selênio/metabolismo , Adulto , Biomarcadores , Dieta , Humanos , Masculino , Pessoa de Meia-Idade , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo , Adulto Jovem
17.
Cell Mol Life Sci ; 76(20): 4131-4144, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31053883

RESUMO

ABCB6 belongs to the family of ATP-binding cassette (ABC) transporters, which transport various molecules across extra- and intra-cellular membranes, bearing significant impact on human disease and pharmacology. Although mutations in the ABCB6 gene have been linked to a variety of pathophysiological conditions ranging from transfusion incompatibility to pigmentation defects, its precise cellular localization and function is not understood. In particular, the intracellular localization of ABCB6 has been a matter of debate, with conflicting reports suggesting mitochondrial or endolysosomal expression. ABCB6 shows significant sequence identity to HMT-1 (heavy metal tolerance factor 1) proteins, whose evolutionarily conserved role is to confer tolerance to heavy metals through the intracellular sequestration of metal complexes. Here, we show that the cadmium-sensitive phenotype of Schizosaccharomyces pombe and Caenorhabditis elegans strains defective for HMT-1 is rescued by the human ABCB6 protein. Overexpression of ABCB6 conferred tolerance to cadmium and As(III) (As2O3), but not to As(V) (Na2HAsO4), Sb(V), Hg(II), or Zn(II). Inactivating mutations of ABCB6 abolished vacuolar sequestration of cadmium, effectively suppressing the cadmium tolerance phenotype. Modulation of ABCB6 expression levels in human glioblastoma cells resulted in a concomitant change in cadmium sensitivity. Our findings reveal ABCB6 as a functional homologue of the HMT-1 proteins, linking endolysosomal ABCB6 to the highly conserved mechanism of intracellular cadmium detoxification.


Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Cádmio/toxicidade , Proteínas de Caenorhabditis elegans/genética , Inativação Metabólica/genética , Poluentes Químicos da Água/toxicidade , Transportadores de Cassetes de Ligação de ATP/deficiência , Transportadores de Cassetes de Ligação de ATP/metabolismo , Animais , Antimônio/toxicidade , Arseniatos/toxicidade , Trióxido de Arsênio/toxicidade , Cádmio/metabolismo , Caenorhabditis elegans/efeitos dos fármacos , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Linhagem Celular Tumoral , Sequência Conservada , Expressão Gênica , Teste de Complementação Genética , Células HeLa , Humanos , Mercúrio/toxicidade , Mutação , Neurônios/citologia , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Schizosaccharomyces/efeitos dos fármacos , Schizosaccharomyces/genética , Schizosaccharomyces/metabolismo , Vacúolos/efeitos dos fármacos , Vacúolos/metabolismo , Poluentes Químicos da Água/metabolismo , Zinco/toxicidade
18.
Toxicol Lett ; 312: 45-54, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31071422

RESUMO

Mercury (Hg) is a heavy metal and Hg exposure is associated with various neural, immune, and cardiovascular abnormalities. However, few studies have evaluated Hg's toxicologic effect on reproductive and metabolic functions. In this study, we assessed whether Hg exposure results in reproductive and metabolic abnormalities. Hg was administered to adult female Wistar rats, mimicking the Hg levels found in exposed human blood, and their reproductive and metabolic function was assessed. Rats exposed to Hg displayed abnormal estrous cyclicity and ovarian follicular development, with a reduction in ovarian antral follicles and an increase in atretic and cystic ovarian follicles. Uterine atrophy with the presence of inflammatory cells was observed in Hg-exposed rats. The presence of abnormal ovarian fat accumulation, as well as increased ovarian lipid drops accumulation, was observed in Hg-exposed rats. Ovarian oxidative stress was also present in the Hg-exposed rats. High fasting glucose levels, glucose, and insulin intolerance were observed in Hg-exposed rats. Thus, these data suggest that Hg exposure led to abnormal reproductive and metabolic features similar to those found in the polycystic ovary syndrome (PCOS) rat models.


Assuntos
Mercúrio/toxicidade , Síndrome do Ovário Policístico/induzido quimicamente , Animais , Glicemia , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Glucose/metabolismo , Teste de Tolerância a Glucose , Resistência à Insulina , Ratos , Ratos Wistar
19.
Environ Sci Pollut Res Int ; 26(16): 16727-16741, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30989610

RESUMO

Cadmium and mercury are non-biodegradable toxic metals that may cause many detrimental effects to the thyroid gland and blood. Vitamin C has been found to be a significant chain-breaking antioxidant and enzyme co-factor against metal toxicity and thus make them less available for animals. The current study was performed to find the effect of individual metals (cadmium and mercury), their co-administration, and the ameliorative effects of vitamin C on some of the parameters that indicate oxidative stress and thyroid dysfunction. Cadmium chloride (1.5 mg/kg), mercuric chloride (1.2 mg/kg), and vitamin C (150 mg/kg of body weight) were orally administered to eight treatment groups of the rabbits (1. control; 2. Vit C; 3. CdCl2; 4. HgCl2; 5. Vit C + CdCl2; 6. Vit C + HgCl2; 7. CdCl2 + HgCl2, and 8. Vit C + CdCl2 + HgCl2). After the biometric measurements of all experimental rabbits, biochemical parameters viz. triidothyronine (T3), thyroxine (T4), thyroid-stimulating hormone (TSH), and triglycerides were measured using commercially available kits. The results exhibited significant decline (p < 0.05) in mean hemoglobin, corpuscular hemoglobin, packed cell volume, T3 (0.4 ± 0.0 ng/ml), and T4 (26.3 ± 1.6 ng/ml) concentration. While, TSH (0.23 ± 0.01 nmol/l) and triglyceride (4.42 ± 0.18 nmol/l) were significantly (p < 0.05) increased but chemo-treatment with Vit C reduces the effects of Cd, Hg, and their co-administration but not regained the values similar to those of controls. This indicates that Vit C had a shielding effect on the possible metal toxicity. The Cd and Hg also found to accumulate in vital organs when measured by atomic absorption spectrophotometer. The metal concentration trend was observed as follows: kidney > liver > heart > lungs. It was concluded that Cd and Hg are toxic and tended to bioaccumulate in different organs and their toxic action can be subdued by vitamin C in biological systems.


Assuntos
Antioxidantes/farmacologia , Ácido Ascórbico/farmacologia , Cádmio/toxicidade , Mercúrio/toxicidade , Glândula Tireoide/efeitos dos fármacos , Hormônios Tireóideos/sangue , Tireotropina/sangue , Animais , Peso Corporal/efeitos dos fármacos , Cádmio/metabolismo , Intoxicação por Metais Pesados , Hemoglobinas/análise , Rim/efeitos dos fármacos , Rim/metabolismo , Fígado/efeitos dos fármacos , Fígado/metabolismo , Mercúrio/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Coelhos , Glândula Tireoide/metabolismo
20.
Cells ; 8(4)2019 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-30987227

RESUMO

A largely understudied microbially mediated mercury (Hg) bioremediative pathway includes the volatilization of Hg2+ to Hg°. Therefore, studies on Hg resistant bacteria (HgR), isolated from historically long-term contaminated environments, can serve as models to understand mechanisms underpinning Hg cycling. Towards this end, a mercury resistant bacterial strain, identified as Stenotrophomonas sp., strain MA5, was isolated from Mill Branch on the Savannah River Site (SRS); an Hg-impacted ecosystem. Minimum inhibitory concentration (MIC) analysis showed Hg resistance of up to 20 µg/mL by MA5 with 95% of cells retaining viability. Microcosm studies showed that the strain depleted more than 90% of spiked Hg2+ within the first 24 h of growth and the detection of volatilized mercury indicated that the strain was able to reduce Hg2+ to Hg°. To understand molecular mechanisms of Hg volatilization, a draft whole genome sequence was obtained, annotated and analyzed, which revealed the presence of a transposon-derived mer operon (merRTPADE) in MA5, known to transport and reduce Hg2+ into Hg°. Based on the whole genome sequence of strain MA5, qRT-PCR assays were designed on merRTPADE, we found a ~40-fold higher transcription of mer T, P, A, D and E when cells were exposed to 5 µg/mL Hg2+. Interestingly, strain MA5 increased cellular size as a function of increasing Hg concentrations, which is likely an evolutionary response mechanism to cope with Hg stress. Moreover, metal contaminated environments are shown to co-select for antibiotic resistance. When MA5 was screened for antibiotic resistance, broad resistance against penicillin, streptomycin, tetracycline, ampicillin, rifampicin, and erythromycin was found; this correlated with the presence of multiple gene determinants for antibiotic resistance within the whole genome sequence of MA5. Overall, this study provides an in-depth understanding of the underpinnings of Stenotrophomonas-mercury interactions that facilitate cellular survival in a contaminated soil habitat.


Assuntos
Mercúrio/toxicidade , Rios/microbiologia , Stenotrophomonas/efeitos dos fármacos , Stenotrophomonas/isolamento & purificação , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Resistência Microbiana a Medicamentos/efeitos dos fármacos , Genes Bacterianos , Mercúrio/isolamento & purificação , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Stenotrophomonas/genética , Stenotrophomonas/crescimento & desenvolvimento , Estresse Fisiológico/efeitos dos fármacos , Transcrição Genética/efeitos dos fármacos , Volatilização
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