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1.
Ecotoxicology ; 29(8): 1128-1137, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32827288

RESUMO

Mercury exposure can disrupt development of the cerebellum, part of the brain essential for coordination of movement through a complex environment, including flight. In precocial birds, such as fowl, the cerebellum develops embryonically, and the chick is capable of leaving the nest within hours of hatching. However, most birds, including all songbirds, are altricial, and spend weeks in the nest between hatching and fledging. The objective of this study was to describe the normal development of the cerebellum in a model altricial songbird so as to determine the effect of exposure to mercury on cerebellar maturation. Adult zebra finch (Taeniopygia guttata) pairs were fed either a control diet, or a diet augmented with one of four treatment-levels of methylmercury (0.3-2.4 µg/g wet weight), and their offspring, the subjects of this study, were fed the same diet by parents. We documented, for the first time, the schedule of cerebellar development in an altricial bird, and compared stages of development among methylmercury-exposed groups. For all treatments of methylmercury, the age of completion of cellular migration was later than for control zebra finches, indicating a delay in cerebellar maturation. Displaced (heterotopic) Purkinje neurons, a pathology typical of methylmercury exposure in developing vertebrate brains, were more numerous in methylmercury-exposed birds, and persisted at least until the age of independence. Delays in maturation of the cerebellum could delay fledging in altricial bird species, with potential serious implications for the fitness of exposed individuals, as predation rates in the nest are often very high.


Assuntos
Cerebelo/crescimento & desenvolvimento , Poluentes Ambientais/toxicidade , Tentilhões , Mercúrio/toxicidade , Animais , Cerebelo/efeitos dos fármacos , Feminino , Masculino
2.
Aquat Toxicol ; 226: 105567, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32745893

RESUMO

The increasing contamination of water bodies with mercury (Hg) raises concerns about the possible effects of this metal on native fish species. Our current understanding of its dynamics in fish organs remains limited. In this study, adult individuals of the native species Astyanax eigenmanniorum were exposed to three environmentally relevant HgCl2 concentrations (5, 100, and 170 µg L-1) for 96 h. To evaluate total Hg (THg) elimination, new individuals were exposed to 100 µg L-1 of HgCl2 (96 h), and at the end of the exposure period, half of the fish were placed in tanks with clean water for 168 h. In both assays, the organs were removed, and THg levels were measured using ICP-MS. The uptake of IHg in A. eigenmanniorum showed a differential accumulation in the organs. Gills, intestine, and brain were the tissues with the highest THg levels. Finally, no elimination of THg in the water was observed, but intestine and gills significantly removed the THg accumulated. Probably a Hg redistribution through the tissues could take place.


Assuntos
Characidae/metabolismo , Mercúrio/metabolismo , Poluentes Químicos da Água/metabolismo , Adulto , Animais , Bioacumulação , Encéfalo/metabolismo , Characidae/sangue , Monitoramento Ambiental , Brânquias/metabolismo , Humanos , Mucosa Intestinal/metabolismo , Mercúrio/análise , Mercúrio/toxicidade , Taxa de Depuração Metabólica , Distribuição Tecidual , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
3.
Environ Sci Pollut Res Int ; 27(32): 40563-40572, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32671705

RESUMO

This study evaluated the toxic effects of inorganic mercury (Hg) in pregnant and lactating rats, as well as the possible protective effect of zinc (Zn) and N-acetylcysteine (NAC). Pregnant and lactating rats were pre-treated with ZnCl2 (27 mg/kg) and/or NAC (5 mg/kg) and after 24 h, they were exposed to HgCl2 (10 mg/kg). Animals were sacrificed 24 h after Hg exposure, and biochemical tests and metal determination were performed. Regarding pregnant rats, Hg exposure caused kidney, blood, and placenta δ-aminolevulinic acid dehydratase (δ-ALA-D) activity inhibition, and the pre-treatments showed a tendency of protection. Moreover, all the animals exposed to Hg presented high Hg levels in the kidney, liver, and placenta when compared with control group. Pregnant rats pre-exposed to Zn (Zn-Hg and Zn/NAC-Hg groups) presented an increase in hepatic metallothionein levels. Therefore, lactating rats exposed to Hg presented renal and blood δ-ALA-D inhibition; the pre-treatments showed a tendency to prevent the renal δ-ALA-D inhibition and prevented the blood δ-ALA-D inhibition caused by Hg. Lactating rats exposed to Hg presented high Hg levels in the kidney and liver. These results showed that 10 mg/kg of HgCl2 causes biochemistry alterations in pregnant and lactating rats, and Zn and NAC present promising results against these damages.


Assuntos
Acetilcisteína , Mercúrio , Acetilcisteína/farmacologia , Animais , Feminino , Rim , Lactação , Fígado , Cloreto de Mercúrio/toxicidade , Mercúrio/toxicidade , Sintase do Porfobilinogênio , Gravidez , Ratos , Zinco
4.
Acta amaz ; 50(2): 142-148, abr - jun. 2020.
Artigo em Inglês | LILACS | ID: biblio-1118376

RESUMO

This is the first study to investigate mercury (Hg) contamination in felid species in the Brazilian Amazon. We collected 26 fur samples from wild felids of four species (Puma concolor, Panthera onca, Leopardus pardalis and Leopardus wiedii) occurring in the Mamirauá and Amanã sustainable development reserves, in the state of Amazonas. Samples were from museum specimens, except for five P. onca samples collected from free-living individuals. Total Hg concentrations ranged from 0.12 to 48.1 µg g-1. Concentrations of Hg did not differ significantly between museum specimens and live individuals of P. onca, but varied significantly among species, with significantly higher concentrations for P. onca and L. pardalis, which could be related to factors such as diet and habitat. (AU)


Assuntos
Metais Pesados , Bioacumulação , Mamíferos , Ecossistema Amazônico , Mercúrio/toxicidade
5.
Ecotoxicol Environ Saf ; 201: 110861, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32544748

RESUMO

Marine biota have been co-challenged with ocean warming and mercury (Hg) pollution over many generations because of human activities; however, the molecular mechanisms to explain their combined effects are not well understood. In this study, a marine planktonic copepod Pseudodiaptomus annandalei was acutely exposed to different temperature (22 and 25 °C) and Hg (0 and 118 µg/L) treatments in a 24-h cross-factored experiment. Hg accumulation and its subcellular fractions were determined in the copepods after exposure. The expression of the genes of superoxide dismutase (SOD), glutathione peroxidase (GPx), metallothionein1 (mt1), heat shock protein 70 (hsp70), hsp90, hexokinase (hk), and pyruvate kinase (pk) was also analyzed. Both the Hg treatment alone and the combined exposure of warmer temperature plus Hg pollution remarkably facilitated Hg bioaccumulation in the exposed copepods. Compared with the Hg treatment alone, the combined exposure increased total Hg accumulation and also the amount of Hg stored in the metal-sensitive fractions (MSF), suggesting elevated Hg toxicity in P. annandalei under a warmer environment, given that the MSF is directly related to metal toxicity. The warmer temperature significantly up-regulated the mRNA levels of mt1, hsp70, hsp90, and hk, indicating the copepods suffered from thermal stress. With exposure to Hg, the mRNA level of SOD increased strikingly but the transcript levels of hsp90, hk, and pk decreased significantly, indicating that Hg induced toxic events (e.g., oxidative damage and energy depletion). Particularly, in contrast to the Hg treatment alone, the combined exposure significantly down-regulated the mRNA levels of SOD and GPx but up-regulated the mRNA levels of mt1, hsp70, hsp90, hk, and pk. Collectively, the results of this study indicate that ocean warming will potentially boost Hg toxicity in the marine copepod P. annandalei, which is information that will increase the accuracy of the projections of marine ecosystem responses to the joint effects of climate change stressors and metal pollution on the future ocean.


Assuntos
Copépodes/efeitos dos fármacos , Temperatura Alta , Mercúrio/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Copépodes/genética , Copépodes/metabolismo , Glutationa Peroxidase/genética , Glutationa Peroxidase/metabolismo , Proteínas de Choque Térmico HSP70/metabolismo , Proteínas de Choque Térmico HSP90/genética , Proteínas de Choque Térmico HSP90/metabolismo , Hexoquinase/genética , Hexoquinase/metabolismo , Mercúrio/farmacocinética , Metalotioneína/genética , Metalotioneína/metabolismo , Piruvato Quinase/genética , Piruvato Quinase/metabolismo , RNA Mensageiro/metabolismo , Superóxido Dismutase/genética , Superóxido Dismutase/metabolismo , Regulação para Cima , Poluentes Químicos da Água/farmacocinética
6.
Ecotoxicol Environ Saf ; 202: 110900, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32593095

RESUMO

Heavy metals such as lead (Pb), cadmium (Cd), and mercury (Hg) are representative neurotoxicological contaminants that can evoke cognitive dysfunctions. Low levels of these contaminants can be detected simultaneously in the human blood. In our previous study, behavioral performances were markedly impaired by exposure to these heavy metal mixtures (MM) at low levels. However, the aspects of cognitive functions involved are not well understood. Here, we further analyzed search strategies using a new algorithm named Morris water maze-unbiased strategy classification (MUST-C). Rat pups were co-exposed to low doses of Pb, Cd, and Hg during the embryonic and lactation stage. MM exposure at low doses, similar to those found in the general population, impaired search strategies even though their latency and path length were not affected in the Morris water maze task. MM-exposed rats preferred to use more directionless repetition strategies and less target orientation strategies than did vehicle-exposed animals in a dose-dependent manner. In addition, thionine staining and electron microscopy further revealed that MM exposure induced dose-dependent search strategy related place cell injures in the hippocampal CA1 and CA3 regions. These results demonstrate that the use of suboptimal search strategies underlies the early cognitive deficits in rats exposed to low doses of MM. The current study determined that search strategy analysis might be a novel sensitive assessment method for evaluating in the neurobehavioral toxicity.


Assuntos
Disfunção Cognitiva/induzido quimicamente , Poluentes Ambientais/toxicidade , Metais Pesados/toxicidade , Animais , Cádmio/toxicidade , Cognição , Feminino , Hipocampo , Humanos , Hormônios Juvenis , Lactação , Masculino , Mercúrio/toxicidade , Ratos
7.
Ecotoxicol Environ Saf ; 201: 110811, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32544744

RESUMO

Xenobiotic mediated renal toxicity is one of the major health concerns to the organisms, including humans. New chemicals with nephrotoxic potential are continuously being added to the list of existing nephrotoxicants. To predict the nephrotoxicity of these new chemicals, reliable and cost-effective alternative animal models are required. It is a prerequisite for the identification and assessment of these compounds as potential nephrotoxicants to prevent renal toxicity in the exposed population. Drosophila melanogaster, a genetically tractable invertebrate animal model, has a renal system functionally analogous to humans. The Malpighian tubules (MTs) of D. melanogaster are similar to the tubular part of nephron of the human kidney. Besides, it recapitulates the renal toxicity hallmark with mammals when exposed to known nephrotoxicants. In this study, first instar larvae of D. melanogaster (Oregon R) were exposed to different concentrations of two well-known nephrotoxicants, cadmium (Cd) and mercury (Hg). Akin to higher organisms, Cd and Hg exposure to D. melanogaster produce similar phenotypes. MTs of exposed D. melanogaster larvae exhibited increased oxidative stress, activated cellular antioxidant defense mechanism, GSH depletion, increased cleaved caspase-3 expression, increased DEVDase activity and increased cell death. The functional status of MTs was assessed by fluid secretion rate (FSR), efflux activity of transporter protein, mitochondrial membrane potential (MMP), ATP level and expression of junctional protein (Dlg). All the phenotypes observed in MTs of D. melanogaster larvae recapitulate the phenotypes observed in higher organisms. Increased uric acid level, the hallmark of renal dysfunction, was also observed in exposed larvae. Taken together, the study suggests that MTs of D. melanogaster may be used as a functional model to evaluate xenobiotic mediated nephrotoxicity.


Assuntos
Alternativas aos Testes com Animais , Cádmio/toxicidade , Drosophila melanogaster/efeitos dos fármacos , Rim/efeitos dos fármacos , Túbulos de Malpighi/efeitos dos fármacos , Mercúrio/toxicidade , Animais , Antioxidantes/metabolismo , Transporte Biológico , Cádmio/metabolismo , Humanos , Rim/metabolismo , Larva/efeitos dos fármacos , Túbulos de Malpighi/metabolismo , Mercúrio/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Xenobióticos/metabolismo , Xenobióticos/toxicidade
8.
Aquat Toxicol ; 224: 105502, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32480176

RESUMO

The present study examined the effect of titanium dioxide nanoparticles (nanoTiO2) and mercury (Hg) compounds on the green alga, Chlamydomonas reinhardtii. Mixtures containing nanoTiO2 of different primary sizes (5 nm, 15 nm and 20 nm), inorganic Hg (IHg) or monomethyl Hg (CH3Hg+, MeHg) were studied and compared with individual treatments. Oxidative stress and membrane damage were examined. Stability of nanoTiO2 materials in terms of hydrodynamic size and surface charge as well as Hg adsorption on different nanoTiO2 materials were characterized. The uptake of Hg compounds in the absence and presence of nanoTiO2 was also quantified. Results show that increasing concentrations of nanoTiO2 with different primary size diminished oxidative stress and membrane damage induced by high concentrations of IHg or MeHg, due to the adsorption of Hg on the nanoTiO2 aggregates and consequent decrease of cellular Hg concentrations. The observed alleviation effect of nanoTiO2 materials on Hg biouptake and toxicity was more pronounced for the materials with smaller primary size. IHg adsorbed onto the nanoTiO2 materials to a higher extent than MeHg. The present study highlights that the effects of contaminants are modulated by the co-existing engineered nanomaterials; therefore, it is essential to get a better understanding of their combined effect in the environment.


Assuntos
Chlamydomonas reinhardtii/efeitos dos fármacos , Mercúrio/toxicidade , Compostos de Metilmercúrio/toxicidade , Nanopartículas/química , Titânio/farmacologia , Poluentes Químicos da Água/toxicidade , Adsorção , Chlamydomonas reinhardtii/metabolismo , Mercúrio/metabolismo , Compostos de Metilmercúrio/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Tamanho da Partícula , Propriedades de Superfície , Titânio/química , Poluentes Químicos da Água/metabolismo
9.
Artigo em Inglês | MEDLINE | ID: mdl-32575788

RESUMO

Prenatal exposure to mercury, stress, and depression may have adverse effects on birth outcomes. Little is known on the influence of chemical and non-chemical stressors on birth outcomes in the country of Suriname. We assessed the influence of prenatal exposure to mercury, perceived stress, and depression on adverse birth outcomes in 1143 pregnant Surinamese women who participated in the Caribbean Consortium for Research in Environmental and Occupational Health-MeKiTamara prospective cohort study. Associations between mercury (≥1.1 µg/g hair, USEPA action level/top versus bottom quartile), probable depression (Edinburgh Depression Scale ≥12), high perceived stress (Cohen's Perceived Stress Scale ≥20), and adverse birth outcomes (low birthweight (<2500 g), preterm birth (<37 completed weeks of gestation), and low Apgar score (<7 at 5 min)) were assessed using bivariate and multivariate logistic regressions. Prevalence of elevated mercury levels, high perceived stress, and probable depression were 37.5%, 27.2%, and 22.4%, respectively. Mercury exposure was significantly associated with preterm birth in the overall study cohort (OR 2.47; 95% CI 1.05-5.83) and perceived stress with a low Apgar score (OR 9.73; 95% CI 2.03-46.70). Depression was not associated with any birth outcomes. These findings can inform policy- and practice-oriented solutions to improve maternal and child health in Suriname.


Assuntos
Depressão , Mercúrio , Nascimento Prematuro , Efeitos Tardios da Exposição Pré-Natal , Estresse Psicológico , Adulto , Região do Caribe , Criança , Feminino , Humanos , Recém-Nascido , Mercúrio/toxicidade , Gravidez , Estudos Prospectivos , Suriname , Adulto Jovem
10.
Toxicol Lett ; 332: 20-26, 2020 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-32569801

RESUMO

The aim of this study was to summarise the available information regarding the partition of toxic metal (Cd, Hg, Mn, Pb) levels in the maternal/foetal unit from large epidemiological studies. We performed a systematic search of PubMed/MedLine, EMBASE, and ISI Web of Science for papers on Cd, total Hg, Mn or Pb levels in the maternal/cord blood that were published in English (n > = 200; 2010-2017). Data on year of publication, sample size, location, year of survey, and main results were extracted. We found a total of 35 papers. Most studies included large convenience samples of healthy pregnant women. The maternal/cord blood was properly used as a biomarker of prenatal exposure to toxic metals. The partition of these toxic metal levels in the maternal/foetal unit was metal-specific. Cd median levels (IQR) in cord blood reported worldwide were much lower [∼ 70 % < LOD = ± 0.11 µg/L] than those found in maternal blood [0.23 µg/L (0.15-0.35), ∼ 65 % > LOD]. Considering that Cd was under LOD in 70 % of the cord blood, Cd cord:maternal ratio as well as Cd cord proportion were not provided. Total Hg median levels (IQR) in cord blood [0.75 µg/L (0.40-1.19), ∼30 % < LOD = ±0.35 µg/L] were usually higher than in maternal blood [0.55 µg/L (0.40-0.85), ∼ 10 % < LOD = ±0.15 µg/L]. Hg cord:maternal ratio was 1.34 (1.00-1.91), and infants born would have Hg cord:(cord + maternal) proportion ranged from 0.50 to 0.63. Mn was the only metal that was detected in 100 % in both maternal (LOD : ±0.50 µg/L) and cord (LOD = ±0.2 µg/L) blood. Mn median levels (IQR) in cord blood [32.96 µg/L (26.90-40.10)] were 2 times higher than in maternal blood [14.01 µg/L (11.50-17.58)]. Mn cord:maternal ratio was 2.35 (1.09-3.80), and infants born would have Mn proportion ranged from 0.52 to 0.79. Pb median levels (IQR) in cord blood [5.79 µg/L (4.34-8.38), ∼ 5% < LOD : ±2.07 µg/L] were usually equal to or lower than those reported in maternal blood [8.07 µg/L (5.79-10.76), ∼ 1% < LOD = ±1.03 µg/L]. Pb cord:maternal ratio was 0.71 (0.59-0.96), and infants born would have Pb proportion ranged from 0.37 to 0.49. Globally, the results indicate that total Hg and Mn levels were lower in maternal blood but higher in cord blood. However, much greater variability was seen with Cd and Pb. At delivery, total Hg and Pb levels in maternal blood were strong predictors of cord blood levels. Our findings empty that understanding the partition, levels and correlations of toxic metals in the maternal/cord blood may help to elucidate the adverse effects of these metals on foetuses and neonates.


Assuntos
Estudos Epidemiológicos , Intoxicação por Metais Pesados/epidemiologia , Troca Materno-Fetal , Metais Pesados/farmacocinética , Metais Pesados/toxicidade , Adulto , Cádmio/farmacocinética , Cádmio/toxicidade , Feminino , Humanos , Lactente , Recém-Nascido , Chumbo/farmacocinética , Chumbo/toxicidade , Manganês/farmacocinética , Manganês/toxicidade , Mercúrio/farmacocinética , Mercúrio/toxicidade , Gravidez
11.
Aquat Toxicol ; 224: 105494, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32422488

RESUMO

Little is known about the impacts of dietary exposure to inorganic mercury (Hg) for a long duration on the health indicators, growth, and disease resistance in Oreochromis niloticus. Accordingly, the current study was designed to assess the effects of Hg contaminated diets on blood biochemistry, growth, chemical composition, Hg bioaccumulation in the tissues, histopathology of liver and head kidneys, and disease resistance to Aeromonas hydrophila of O. niloticus. Also, the efficiency of citronella oil, geranium oil (GO), curcumin (CUR), Bacillus toyonensis (BT), and Bacillus subtilis (BS) as dietary supplements on reversing the negative impacts of Hg were assessed. A total of 240 tilapia fingerlings were assigned to eight dietary treatments fed on the basal diet (G1), G1 diet contaminated with 50 ppm Hg (G2), whereas the other groups fed the G2 diet and enriched with 400 mg CO (G3), 400 mg GO (G4), 200 mg CUR (G5), 7 × 107 cells BT (G6), 7 × 107 cells BS (G7), and 7 × 107 BT + BS/ kg diet (G8) for 16 weeks. The obtained results showed that fish fed on the G2 diet had significantly impaired growth performance indicators, blood parameters, and resistance to bacterial infection compared with fish in the control group. Additionally, distinct pathological perturbations in liver and head kidneys were observed. In contrast, fish groups G3 to G8 had a significant enhancement in the growth performance, Hg bioaccumulation in fish tissues, blood biochemistry, and resistance against A. hydrophila infection compared with fish in the G2 group. Maximum improvement was recorded in G5, G6, and G8. Conclusively, from both health and an economic point of view, these results suggested that several benefits might be gained by adding these additives, especially CUR, BT, and BT + BS, on growth enhancement and ameliorating Hg negative impacts in O. niloticus.


Assuntos
Ração Animal/análise , Bioacumulação , Ciclídeos/crescimento & desenvolvimento , Resistência à Doença/efeitos dos fármacos , Doenças dos Peixes/prevenção & controle , Infecções por Bactérias Gram-Negativas/veterinária , Mercúrio/toxicidade , Poluentes Químicos da Água/toxicidade , Aeromonas hydrophila/patogenicidade , Animais , Ciclídeos/imunologia , Ciclídeos/microbiologia , Dieta , Suplementos Nutricionais , Resistência à Doença/imunologia , Doenças dos Peixes/imunologia , Doenças dos Peixes/microbiologia , Infecções por Bactérias Gram-Negativas/imunologia , Infecções por Bactérias Gram-Negativas/microbiologia , Rim Cefálico/efeitos dos fármacos , Rim Cefálico/metabolismo , Rim Cefálico/patologia , Fígado/efeitos dos fármacos , Fígado/metabolismo , Fígado/patologia , Mercúrio/metabolismo , Poluentes Químicos da Água/metabolismo
12.
Environ Monit Assess ; 192(6): 330, 2020 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-32372388

RESUMO

The present study investigated the acute (72 h) and sub-acute (14 days) toxicity of mercury, lead, and cadmium to the green microalga, Nannochloropsis oculata. The acute toxicity testing was conducted according to the modified OECD guideline (No. 201). The 72-h IC50 values of Hg, Pb, and Cd exposed to N. oculata were 0.87, 1.81, and 4.97 mg/L, respectively. These results showed that mercury is about twice as toxic as lead and about 5.7 times more toxic than cadmium to this marine microalga. Lead is about 2.7 times more toxic than cadmium. The chlorophyll a content of the microalga decreased in the 10th and 14th days of the sub-acute toxicity test. Although the carotenoid content increased following exposure to the low levels of tested heavy metals (which may show the protective role of carotenoids against oxidative stress), with increased exposure time the total carotenoid reduced compared to control. A regular monitoring program to examine the level of metals in the aquatic ecosystem for protecting microalgae should be implemented.


Assuntos
Clorofila A , Monitoramento Ambiental , Metais Pesados , Microalgas , Poluentes Químicos da Água , Cádmio/toxicidade , Clorofila A/metabolismo , Ecossistema , Exposição Ambiental , Chumbo/toxicidade , Mercúrio/toxicidade , Metais Pesados/toxicidade , Microalgas/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade
13.
Artigo em Inglês | MEDLINE | ID: mdl-32419600

RESUMO

The mining sector in South Africa is expected to be the fifth largest in the world. Both mining and transport are the most common reasons for an increased risk of human exposure to heavy metal contamination in South Africa. Due to increasing amounts of metals in the environment, this study identified three metals cadmium, chromium and mercury based on the risk of exposure in South Africa. The aim of this study was to investigate the changes in the morphology of the spleen tissue of male Sprague-Dawley rats exposed to these metals alone and in combination by using light microscopy. Forty eight animals in eight experimental groups were exposed, via oral gavage, to these metals at 1000× the World Health Organization's acceptable water limits of each respective metal, alone and in combination, for 28 days. Changes in the histological structure of the spleen were observed using haematoxylin and eosin and picrosirius red staining. Necrosis was observed in all the groups, with the severity varying between the different exposure groups, alone or in combination. Fibrosis in the spleen tissue was only seen in the experimental groups exposed to cadmium and mercury respectively, as well as in the combination of cadmium and mercury.


Assuntos
Cádmio/toxicidade , Cromo/toxicidade , Poluentes Ambientais/toxicidade , Mercúrio/toxicidade , Baço/efeitos dos fármacos , Baço/patologia , Animais , Cádmio/sangue , Cromo/sangue , Poluentes Ambientais/sangue , Fibrose , Humanos , Masculino , Mercúrio/sangue , Mineração , Ratos , Ratos Sprague-Dawley , África do Sul
15.
Chemosphere ; 253: 126645, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32283423

RESUMO

Worldwide shark populations have experienced rapid declines over the last decades, mainly due to overfishing. Marine protected areas (MPAs) have thus become an indispensable tool for the protection of these marine predators. Two recently-created MPAs in the Northeast Pacific Ocean, the Revillagigedo National Park and Clipperton Atoll, are characterized by different trophic structures potentially influencing the trophic niche and contaminant exposure of resident sharks in these two sites. In this context, we used carbon (δ13C) and nitrogen (δ15N) stable isotope analyzes as well as total mercury concentrations ([THg]) to assess the effect of foraging site on the trophic niche and Hg levels of juvenile silvertip (ST) sharks Carcharhinus albimarginatus. Analyzing fin clip samples from Revillagigedo and Clipperton, we found that shark δ15N varied spatially in relation to δ15N baselines, suggesting similar trophic position in both MPAs. Moreover, δ13C values indicated that ST sharks from Revillagigedo would feed on different food webs (i.e. both benthic and pelagic) while individuals from Clipperton would only rely on benthic food webs. These differences between MPAs led to a weak overlap of isotopic niches between the two populations, highlighting the site residency of juvenile ST sharks. Within each population, [THg] was not correlated with trophic tracers (δ15N and δ13C) and was also similar between populations. This study revealed no influence of site or food web in [THg] and raises the question of the origin of Hg exposure for reef shark populations in the Northeast Pacific Ocean.


Assuntos
Mercúrio/toxicidade , Tubarões/fisiologia , Poluentes Químicos da Água/toxicidade , Animais , Conservação dos Recursos Naturais , Pesqueiros , Cadeia Alimentar , Isótopos , Mercúrio/metabolismo , Isótopos de Nitrogênio/análise , Oceano Pacífico , Alimentos Marinhos , Poluentes Químicos da Água/metabolismo
16.
Ecotoxicol Environ Saf ; 195: 110472, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32199219

RESUMO

The mercury residue in soil not only poisons plants, but also bioaccumulates and biomagnifies through the food chain, causing a significant risk to human health. As an essential condiment on the table, the food safety of ginger should be focused on. Using soil culture experiments, this study aimed to identify the response of ginger growth to mercury pollution, assess the transmission and residue of mercury in different product organs and explore the mitigation mechanism of silicon on mercury toxicity. Effects of soil mercury pollution on ginger growth showed hormesis and time effect. Long-term mercury pollution led to growth inhibition and quality degradation of ginger, eventually reducing its yield by 25.96% (mercury = 9 mg kg-1). Contents of mercury and silicon in different organs both were the highest in root, followed by rhizome, less in stem and leaf, especially the mercury residue in rhizome manifested as Mother-ginger > Son-ginger > Grandson-ginger. At 6 mg kg-1 soil mercury level, the mercury residue of Mother-ginger exceeds the edible pollutant limit standard (China) by 10.7 times, which makes no obvious risk after being consumed by adults, but poses a potential health threat to children. Notably, it is safer to consume the newly sprouted and inflated tender ginger. Application of silicon fertilizer could alleviate mercury toxicity, mainly by promoting ginger root growth and leaf pigment synthesis, stimulating water-gas exchange system, fluorescence system and antioxidant system to make an anti-stress response. 2 mg kg-1 silicon fertilizer had the most significant mitigation effect on mercury stress, which increased the yield of ginger by 24.85% and reduced the mercury residue of ginger block by 44.44%-60.17%.


Assuntos
Gengibre/efeitos dos fármacos , Mercúrio/toxicidade , Silício/farmacologia , Poluentes do Solo/toxicidade , Antioxidantes/metabolismo , Fertilizantes , Gengibre/crescimento & desenvolvimento , Gengibre/metabolismo , Mercúrio/farmacocinética , Folhas de Planta/química , Rizoma/metabolismo , Medição de Risco , Poluentes do Solo/farmacocinética
17.
Artigo em Inglês | MEDLINE | ID: mdl-32166694

RESUMO

Hypoxia and mercury contamination often co-occur in tropical freshwater ecosystems, but the interactive effects of these two stressors on fish populations are poorly known. The effects of mercury (Hg) on recorded changes in the detailed form of the electrocardiogram (ECG) during exposure to progressive hypoxia were investigated in two Neotropical freshwater fish species, matrinxã, Brycon amazonicus and traíra, Hoplias malabaricus. Matrinxã were exposed to a sublethal concentration of 0.1 mg L-1 of HgCl2 in water for 96 h. Traíra were exposed to dietary doses of Hg by being fed over a period of 30 days with juvenile matrinxãs previously exposed to HgCl2, resulting in a dose of 0.45 mg of total Hg per fish, each 96 h. Both species showed a bradycardia in progressive hypoxia. Hg exposure impaired cardiac electrical excitability, leading to first-degree atrioventricular block, plus profound extension of the ventricular action potential (AP) plateau. Moreover, there was the development of cardiac arrhythmias and anomalies such as occasional absence of QRS complexes, extra systoles, negative Q-, R- and S-waves (QRS complex), and T wave inversion, especially in hypoxia below O2 partial pressures (PO2) of 5.3 kPa. Sub-chronic dietary Hg exposure induced intense bradycardia in normoxia in traira, plus lengthening of ventricular AP duration coupled with prolonged QRS intervals. This indicates slower ventricular AP conduction during ventricular depolarization. Overall, the data indicate that both acute waterborne and sub-chronic dietary exposure (trophic level transfer), at sublethal concentrations of mercury, cause damage in electrical stability and rhythm of the heartbeat, leading to myocardial dysfunction, which is further intensified during hypoxia. These changes could lead to impaired cardiac output, with consequences for swimming ability, foraging capacity, and hence growth and/or reproductive performance.


Assuntos
Peixes/fisiologia , Mercúrio/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Caraciformes , Ecossistema , Eletrocardiografia , Eutrofização , Água Doce , Hipóxia
18.
Artigo em Inglês | MEDLINE | ID: mdl-32155754

RESUMO

Aluminium (Al) is a non-essential neurotoxicant and there is limited information regarding exposure to Al in utero. This study sought to evaluate the in utero exposure to Al in urban South African women, its effects on birth outcomes and possible synergistic effects between Al, essential and neurotoxic elements such as lead (Pb), mercury (Hg) and arsenic (As), as well as a a potential sex-dependent response to these elements in neonates. This study has found elevated levels of Al in urban women at delivery. The Spearman's rank correlation coefficients (p-value) of the association between maternal serum Al and birth outcomes (gestational age and parity), and between maternal serum Al and Cu, Zn and Se, were statistically significant. However, in the general and the stratified models, no association was found between any of the birth outcomes and maternal serum Al. The association between maternal serum Al and neurotoxic elements at delivery showed a significant positive correlation for Pb only (rho = 0.361; p < 0.001) which was found to be sex-dependent in neonates (males, rho = 0.285; p < 0.004 and females, rho = 0.444, p < 0.001). Our preliminary findings indicate that in utero exposure to Al is an emerging concern requiring further research and directives from public health authorities.


Assuntos
Alumínio , Arsênico , Mercúrio , Oligoelementos , Adulto , Alumínio/toxicidade , Arsênico/toxicidade , Feminino , Idade Gestacional , Humanos , Recém-Nascido , Masculino , Exposição Materna , Mercúrio/toxicidade , Gravidez , Resultado da Gravidez , Oligoelementos/toxicidade , Adulto Jovem
19.
Ecotoxicol Environ Saf ; 192: 110238, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32036095

RESUMO

Mercury (Hg) is an extremely dangerous environmental contaminant, responsible for human diseases including neurological disorders. However, the mechanisms of inorganic Hg (iHg)-induced cell death and toxicity are little known. Dihydrolipoic acid (DHLA) is the reduced form of a naturally occurring compound lipoic acid, which act as a potent antioxidant through multiple mechanisms. So we hypothesized that DHLA has an inhibitory role on iHg-cytotoxicity. The purposes of this research were to investigate mechanism/s of cytotoxicity of iHg, as well as, the cyto-protection of DHLA against iHg induced toxicity using PC12 cells. Treatment of PC12 cells with HgCl2 (Hg2+) (0-2.5 µM) for 48 h resulted in significant toxic effects, such as, cell viability loss, high level of lactate dehydrogenase (LDH) release, DNA damage, cellular glutathione (GSH) level decrease and increased Hg accumulation. In addition, protein level expressions of akt, p-akt, mTOR, GR, NFkB, ERK1, Nrf2 and HO-1 in cells were downregulated; and cleaved caspase 3 and cytochrome c release were upregulated after Hg2+ (2.5 µM) exposure and thus inducing apoptosis. Hg2+induced apoptosis was also confirmed by flow cytometry. However, pretreatment with DHLA (50 µM) for 3 h before Hg2+ (2.5 µM) exposure showed inhibition against iHg2+-induced cytotoxicity by reversing cell viability loss, LDH release, DNA damage, GSH decrease and inhibiting Hg accumulation. Moreover, DHLA pretreatment reversed the protein level expressions of akt, p-akt, mTOR, GR, NFkB, ERK1, Nrf2, HO-1, cleaved caspase 3 and cytochrome c. In conclusion, results showed that DHLA could attenuate Hg2+-induced cytotoxicity via limiting Hg accumulation, boosting up of antioxidant defense, and inhibition of apoptosis in cells.


Assuntos
Apoptose/efeitos dos fármacos , Poluentes Ambientais/toxicidade , Mercúrio/toxicidade , Ácido Tióctico/análogos & derivados , Animais , Antioxidantes/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Dano ao DNA , Poluentes Ambientais/metabolismo , Glutationa/metabolismo , Mercúrio/metabolismo , Células PC12 , Ratos , Transdução de Sinais/efeitos dos fármacos , Ácido Tióctico/farmacologia
20.
Artigo em Chinês | MEDLINE | ID: mdl-32062889

RESUMO

Objective: To investigate the relationship between renal injury and apoptosis in rats with nephrotic syndrome induced by mercury, in order to find out the pathogenesis. Methods: Forty-eight healthy male SPF-grade BN (Brown-Norway) rats were divided into the control group and the exposure group by random number table. The nephrotic syndrome was caused by subcutaneous injection of HgCl(2) (1 mg/ml) in the abdominal weight per kg of body weight. The control group was injected with the same volume of NaCl as the exposure group. Some rats were sacrificed on the 14th, 21st, 28th, and 35th days, and the serum kidney injury indicators creatinine (CRE) and urea nitrogen (BUN) were detected, and the renal tissue mercury content was detected; the in situ terminal transferase labeling technology (TUNEL) was detected Apoptosis, immunofluorescence detection of Cyt C content, Western blot detection of mitochondrial pathway apoptosis-related proteins [B-cell lymphoma 2 (Bcl-2) , Bcl-2 related X protein (BAX) , cysteine proteinase 3 (Caspase 3) ], mitogen-activated protein kinase (MAPK) signaling pathway-related proteins[p38 mitogen-activated protein kinase (P38MAPK) , extracellular regulatory protein kinase (ERK) ] expression. Results: Compared with the control group, the BUN content in the serum of rats in the exposure group was significantly increased on days 7, 21, and 28, the CRE content was significantly increased on 21 days, the CRE content was significantly decreased on 28 and 35 days, and the organ coefficient and renal mercury content were 14 to 35 days. Significantly increased, and the differences were statistically significant (P<0.05) . Compared with the control group, rats in the exposed group showed increased glomerular stroma, tubule dilatation and other renal cell apoptosis at 14 to 35 days, and Cyt C expression was obvious in the exposed groups at 14, 21 days. Compared with the control group, the BAX content of the rats in the exposed group was significantly increased on the 21st day, the content of Caspase 3 in the rats on the 14th and 21st days was significantly increased, and the content of the P38MAPK in the 35th day was significantly increased (P<0.05) . Conclusion: HgCl(2) may cause renal cell damage through the mitochondrial pathway of apoptosis and cause nephrotic syndrome, and the MAPK signaling pathway may regulate this process and exert an inhibitory effect on apoptosis.


Assuntos
Apoptose , Mercúrio/toxicidade , Síndrome Nefrótica/patologia , Animais , Rim/patologia , Sistema de Sinalização das MAP Quinases , Masculino , Mitocôndrias , Síndrome Nefrótica/induzido quimicamente , Ratos
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