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1.
Ecotoxicol Environ Saf ; 207: 111224, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32890955

RESUMO

The roots of 4 japonica, 4 indica, and 7 hybrid rice varieties were obtained by hydroponic experiment and used to explore the relationship between charge characteristics and exchangeable manganese(II) (Mn(II)) on rice roots and Mn(II) absorption in roots and shoots of the rice. Results indicated Mn(II) adsorbed on rice roots mainly existed as exchangeable Mn(II) after 2 h. The roots of indica and hybrid rice carried more negative charges than the roots of japonica rice. Accordingly, this led to more exchangeable Mn(II) to be adsorbed on roots of indica and hybrid rice after 2 h and more Mn(II) absorbed in the roots of the same varieties after 48 h. However, this was contrary to the result of Mn(II) absorption in rice shoots after 48 h. Coexisting cations of K+, Na+, Ca2+, and Mg2+ reduced the exchangeable Mn(II) on rice roots through their competition with Mn(II) for sorption sites on rice roots, which led to the decrease in Mn(II) absorption in rice roots and shoots. Ca2+ and Mg2+ showed a greater decrease in the Mn(II) absorbed in roots and shoots than K+ and Na+. The reduction of Mn(II) absorption in the roots of indica rice and hybrid rice induced by Ca2+ and Mg2+ was more than that of japonica rice. This was attributed to more negative charges on the roots of the former than the latter. Therefore, the absorption of Mn(II) by rice roots was determined by surface charge properties and exchangeable Mn(II) on the rice roots. The results suggested that Ca2+ and Mg2+ have potential to alleviate Mn(II) toxicity to rice.


Assuntos
Manganês/toxicidade , Oryza/metabolismo , Poluentes do Solo/toxicidade , Adsorção , Manganês/metabolismo , Oryza/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos , Poluentes do Solo/metabolismo
2.
Ecotoxicol Environ Saf ; 207: 111537, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33254399

RESUMO

Despite being an essential trace element with great importance for vital metabolic activities, the manganese (Mn) can also cause damage to organ systems. However, data on the effect of this metal on the male reproductive system are limited, especially using relevant doses to human exposure. The present study aimed to evaluate and compare the effects of Mn exposure on the testicular structure of mice. Three experiments were conducted: (I) direct exposure to realistic doses (0.013, 0.13, and 1.3 mg/kg/day of MnCl2); (II) parental and direct exposure to realistic doses (as in experiment I), where the animals were exposed during intrauterine development and from lactation until reproductive maturity; (III) direct exposure to high doses (15, 30, and 60 mg/kg/day of MnCl2). Biometric, histopathological, histomorphometric and stereological parameters of the testis were evaluated, in addition to sperm morphology. Bioinformatic analyses were performed to identify potential Mn binding sites in 3ß-HSD and P450ssc, as well as their protein-protein interaction network. The results obtained were compared using the integrated biomarker response index (IBR). There was an increase of seminiferous tubules pathologies in all experimental conditions tested, with effects on tubular volume, as well as a reduction in tubular diameter. The IBR analyses showed that parental and direct exposure had a significant negative effect on the testicular structure due to the exposure of this metal to sensitive periods of animal development. This study suggests that Mn has the potential to alter the morphological parameters of the testes, affecting the spermatogenesis in mice.


Assuntos
Poluentes Ambientais/toxicidade , Manganês/toxicidade , Testículo/anatomia & histologia , Animais , Feminino , Lactação/efeitos dos fármacos , Masculino , Camundongos , Espermatogênese/efeitos dos fármacos , Testículo/efeitos dos fármacos , Testes de Toxicidade
3.
J Toxicol Sci ; 45(10): 619-624, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33012730

RESUMO

Manganese (Mn) poisoning may result in a neurological disorder called manganism. Although the neurotoxic mechanism of Mn is unclear, oxidative stress may be involved based on the interactions between neurotransmitter catecholamines and metals such as iron. Here, we propose a novel mechanism in which Mn oxidizes catecholamines and inhibits cellular transcription. Mn accelerated the oxidation of adrenaline (Ad) and produced adrenochrome (AdC) more effectively than iron. Furthermore, the oxidation of DNA bases increased when Ad, Mn, and iron were present. However, despite the absence of iron, cell viability decreased in the presence of AdC or Ad with Mn, which suggests there is another mechanism independent of oxidative DNA damage. AdC or preincubated Ad with Mn reduced mRNA synthesis in T7 RNA polymerase-driven transcription. RNA synthesis decreased in AdC-treated cells dose-dependently. These results show that Mn disrupts neuronal function via catecholamine oxidation-mediated transcriptional inhibition.


Assuntos
Catecolaminas/genética , Catecolaminas/metabolismo , Intoxicação por Manganês , Manganês/toxicidade , Transcrição Genética/efeitos dos fármacos , Adrenocromo/metabolismo , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Dano ao DNA/efeitos dos fármacos , Relação Dose-Resposta a Droga , Epinefrina/metabolismo , Humanos , Ferro/metabolismo , Oxirredução/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , RNA Mensageiro/metabolismo
4.
Ecotoxicol Environ Saf ; 203: 111010, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888587

RESUMO

Manganese (Mn) toxicity is common in plants grown on very acid soils. However, some plants species that grow in this condition can take up high amounts of Mn and are referred to as hyperaccumulating species. In this study, we evaluated the capacity of Ilex paraguariensis to accumulate Mn and the effect of excessive concentrations on plant growth and nutrition. For this, a container experiment was conducted using soils from different parent materials (basalt and sandstone), with and without liming, and at six doses of applied Mn (0, 30, 90, 270, 540 and 1,080 mg kg-1). Clonal plants grown for 203 days were harvested to evaluate yield, and leaf tissue samples were evaluated for Mn and other elements. Without liming and with high Mn doses, leaf Mn concentrations reached 13,452 and 12,127 mg kg-1 in sandstone and basalt soils, respectively; concentrations in excess of 10,000 mg kg-1 are characteristic of hyperaccumulating plants. Liming reduced these values to 7203 and 8030 mg kg-1. More plant growth accompanied increased Mn leaf concentrations, with a growth reduction noted at the highest dose in unlimed soils. Elemental distribution showed Mn presence in the mesophyll, primarily in vascular bundles, without high Mn precipitates. Interveinal chlorosis of young leaves associated with high Mn concentration and lower Fe concentrations was observed, especially in sandstone soil without liming. However, the occurrence of this symptom was not associated with decreased plant growth.


Assuntos
Ácidos/farmacologia , Ilex paraguariensis/metabolismo , Manganês/metabolismo , Doenças das Plantas/induzido quimicamente , Poluentes do Solo/metabolismo , Ácidos/análise , Compostos de Cálcio/análise , Compostos de Cálcio/farmacologia , Ilex paraguariensis/efeitos dos fármacos , Ilex paraguariensis/crescimento & desenvolvimento , Ferro/metabolismo , Manganês/análise , Manganês/toxicidade , Óxidos/análise , Óxidos/farmacologia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Solo/química , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
5.
Artigo em Inglês | MEDLINE | ID: mdl-32916867

RESUMO

This study assessed the significance and potential impact of potentially toxic element (PTE) (i.e., Mn, Pb, Cu, Zn, Cr, Cd, and Ni) pollution in the surface soil from an abandoned manganese mining area in Xiangtan City, Hunan Province, China, on the health of residents. The risks were sequentially evaluated using a series of protocols including: the geo-accumulation index (Igeo), pollution load index (PLI), potential ecological risk index (RI), and implications for human health from external exposures using the hazard quotient (HQ), hazard index (HI) and carcinogenic risk (CR). The results revealed that Mn and Cd were the major pollutants in the soil samples. The ecological risk assessment identified moderate risks, which were mainly derived from Cd (82.91%). The results of the health risk assessment revealed that generally across the area, the non-carcinogenic risk was insignificant, and the carcinogenic risk was at an acceptable level. However, due to local spatial fluctuation, some of the sites presented a non-carcinogenic risk to children. The soil ingestion pathway is the main route of exposure through both non-carcinogenic and carcinogenic risks, with Mn being the major contributor to non-carcinogenic risk, with Cr and Cd the major contributors to carcinogenic risk. In addition, three pollution sources were identified through the Pearson correlation coefficient and principal component analysis (PCA), which included: a. mining activities and emissions from related transportation; b. natural background; c. agricultural management practices and municipal sewage discharge. The study provides information on the effects of spatial variation for the development of the abandoned mining areas and a useful approach to the prioritization of locations for the development and utilization of soil in these areas in China.


Assuntos
Metais Pesados , Mineração , Poluentes do Solo , Criança , China , Cidades , Monitoramento Ambiental , Humanos , Manganês/toxicidade , Metais Pesados/análise , Medição de Risco , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
6.
Ecotoxicol Environ Saf ; 202: 110904, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800239

RESUMO

Cation diffusion facilitators (CDFs) play central roles in metal homeostasis and tolerance in plants, but the specific functions of Camellia sinensis CDF-encoding genes and the underlying mechanisms remain unknown. Previously, transcriptome sequencing results in our lab indicated that the expression of CsMTP8.2 in tea plant shoots was down-regulated exposed to excessive amount of Mn2+ conditions. To elucidate the possible mechanisms involved, we systematically identified 13 C. sinensis CsMTP genes from three subfamilies and characterized their phylogeny, structures, and the features of the encoded proteins. The transcription of CsMTP genes was differentially regulated in C. sinensis shoots and roots in responses to high concentrations of Mn, Zn, Fe, and Al. Differences in the cis-acting regulatory elements in the CsMTP8.1 and CsMTP8.2 promoters suggested the expression of these two genes may be differentially regulated. Transient expression analysis indicated that CsMTP8.2 was localized to the plasma membrane in tobacco and onion epidermal cells. Moreover, when heterologously expressed in yeast, CsMTP8.2 conferred tolerance to Ni and Mn but not to Zn. Additionally, heterologous expression of CsMTP8.2 in Arabidopsis thaliana revealed that CsMTP8.2 positively regulated the response to manganese toxicity by decreasing the accumulation of Mn in plants. However, there was no difference in the accumulation of other metals, including Cu, Fe, and Zn. These results suggest that CsMTP8.2 is a Mn-specific transporter that contributes to the efflux of excess Mn2+ from plant cells.


Assuntos
Camellia sinensis/genética , Manganês/toxicidade , Poluentes do Solo/toxicidade , Arabidopsis/metabolismo , Membrana Celular/metabolismo , Regulação da Expressão Gênica de Plantas , Manganês/metabolismo , Filogenia , Células Vegetais/metabolismo , Proteínas de Plantas/metabolismo , Raízes de Plantas/metabolismo , Brotos de Planta/metabolismo , Saccharomyces cerevisiae/metabolismo , Chá
7.
Plant Physiol Biochem ; 155: 231-242, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32781273

RESUMO

Manganese (Mn) is an essential micronutrient for plant growth. However, excess manganese is toxic and inhibits crop production. Although it is widely known that physiological and molecular mechanisms underlie plant responses to Mn toxicity, few studies have been conducted to compare Mn tolerance capabilities between young and old leaves in plants; thus, the mechanisms underlying Mn tolerance in different plant tissues or organs are not fully understood. In this study, the dose responses of soybean to Mn availability were investigated. Genome-wide transcriptomic analysis was subsequently conducted to identify the differentially expressed genes (DEGs) in both young and old leaves of soybean in responses to Mn toxicity. Our results showed that excess Mn severely inhibited soybean growth and increased both Mn accumulation in and brown spots on soybean leaves, especially for the old leaves, strongly suggesting that more Mn was allocated to old leaves in soybean. Transcriptomic profiling revealed that totals of 4410 and 2258 DEGs were separately identified in young leaves and old leaves. Furthermore, only 944 DEGs were found to be commonly regulated in both young and old leaves of soybean, strongly suggesting distinct responses present in soybean young and old leaves in responses to Mn toxicity.


Assuntos
Regulação da Expressão Gênica de Plantas , Manganês/toxicidade , Soja/genética , Folhas de Planta/efeitos dos fármacos , Soja/efeitos dos fármacos , Transcriptoma
8.
Ecotoxicol Environ Saf ; 203: 110975, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32678756

RESUMO

Manganese (Mn) produces cholinergic neuronal loss in basal forebrain (BF) region that was related to cognitive dysfunction induced after single and repeated Mn treatment. All processes that generate cholinergic neuronal loss in BF remain to be understood. Mn exposure may produce the reduction of BF cholinergic neurons by increasing amyloid beta (Aß) and phosphorylated Tau (pTau) protein levels, altering heat shock proteins' (HSPs) expression, disrupting proteasome P20S activity and generating oxidative stress. These mechanisms, described to be altered by Mn in regions different than BF, could lead to the memory and learning process alteration produced after Mn exposure. The research performed shows that single and repeated Mn treatment of SN56 cholinergic neurons from BF induces P20S inhibition, increases Aß and pTau protein levels, produces HSP90 and HSP70 proteins expression alteration, and oxidative stress generation, being the last two effects mediated by NRF2 pathway alteration. The increment of Aß and pTau protein levels was mediated by HSPs and proteasome dysfunction. All these mechanisms mediated the cell decline observed after Mn treatment. Our results are relevant because they may assist to reveal the processes leading to the neurotoxicity and cognitive alterations observed after Mn exposure.


Assuntos
Peptídeos beta-Amiloides/metabolismo , Prosencéfalo Basal/efeitos dos fármacos , Neurônios Colinérgicos/efeitos dos fármacos , Poluentes Ambientais/toxicidade , Proteínas de Choque Térmico HSP70/metabolismo , Proteínas de Choque Térmico HSP90/metabolismo , Manganês/toxicidade , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteínas tau/metabolismo , Animais , Prosencéfalo Basal/metabolismo , Prosencéfalo Basal/patologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Neurônios Colinérgicos/metabolismo , Neurônios Colinérgicos/patologia , Relação Dose-Resposta a Droga , Poluentes Ambientais/metabolismo , Manganês/metabolismo , Camundongos , Estresse Oxidativo/efeitos dos fármacos
9.
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
10.
Ecotoxicol Environ Saf ; 201: 110712, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32502905

RESUMO

Exposure to manganese (Mn) can cause male reproductive damage and lead to abnormal secretion of sex hormones. Gonadotropin-releasing hormone (GnRH) plays an important role in the neuromodulation of vertebrate reproduction. Astrocytes can indirectly regulate the secretion of GnRH by binding paracrine prostaglandin E2 (PGE2) specifically to the EP1 and EP2 receptors on GnRH neurons. Prior studies assessed the abnormal secretion of GnRH caused by Mn exposure, but the specific mechanism has not been reported in detail. This study investigated the effects of Mn exposure on the reproductive system of male mice to clarify the role of PGE2 in the abnormal secretion of GnRH in the hypothalamus caused by exposure to Mn. Our data demonstrate that antagonizing the EP1 and EP2 receptors of PGE2 can restore abnormal levels of GnRH caused by Mn exposure. Mn exposure causes reduced sperm count and sperm shape deformities. These findings suggest that EP1 and EP2, the receptors of PGE2, may be the key to abnormal GnRH secretion caused by Mn exposure. Antagonizing the PGE2 receptors may reduce reproductive damage caused by Mn exposure.


Assuntos
Hormônio Liberador de Gonadotropina/metabolismo , Hipotálamo/efeitos dos fármacos , Manganês/toxicidade , Receptores de Prostaglandina E Subtipo EP1/metabolismo , Receptores de Prostaglandina E Subtipo EP2/metabolismo , Reprodução/efeitos dos fármacos , Animais , Hipotálamo/metabolismo , Masculino , Manganês/metabolismo , Camundongos , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Receptores de Prostaglandina E Subtipo EP1/antagonistas & inibidores , Receptores de Prostaglandina E Subtipo EP2/antagonistas & inibidores
11.
J Neurosci ; 40(30): 5871-5891, 2020 07 22.
Artigo em Inglês | MEDLINE | ID: mdl-32576620

RESUMO

Manganese exposure produces Parkinson's-like neurologic symptoms, suggesting a selective dysregulation of dopamine transmission. It is unknown, however, how manganese accumulates in dopaminergic brain regions or how it regulates the activity of dopamine neurons. Our in vivo studies in male C57BLJ mice suggest that manganese accumulates in dopamine neurons of the VTA and substantia nigra via nifedipine-sensitive Ca2+ channels. Manganese produces a Ca2+ channel-mediated current, which increases neurotransmitter release and rhythmic firing activity of dopamine neurons. These increases are prevented by blockade of Ca2+ channels and depend on downstream recruitment of Ca2+-activated potassium channels to the plasma membrane. These findings demonstrate the mechanism of manganese-induced dysfunction of dopamine neurons, and reveal a potential therapeutic target to attenuate manganese-induced impairment of dopamine transmission.SIGNIFICANCE STATEMENT Manganese is a trace element critical to many physiological processes. Overexposure to manganese is an environmental risk factor for neurologic disorders, such as a Parkinson's disease-like syndrome known as manganism. We found that manganese concentration-dependently increased the excitability of dopamine neurons, decreased the amplitude of action potentials, and narrowed action potential width. Blockade of Ca2+ channels prevented these effects as well as manganese accumulation in the mouse midbrain in vivo Our data provide a potential mechanism for manganese regulation of dopaminergic neurons.


Assuntos
Neurônios Dopaminérgicos/efeitos dos fármacos , Neurônios Dopaminérgicos/metabolismo , Manganês/metabolismo , Manganês/toxicidade , Potenciais de Ação/efeitos dos fármacos , Potenciais de Ação/fisiologia , Animais , Células Cultivadas , Relação Dose-Resposta a Droga , Células HEK293 , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Técnicas de Cultura de Órgãos
12.
Biochim Biophys Acta Mol Cell Res ; 1867(10): 118787, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32592735

RESUMO

Manganese (Mn) plays an important role in many physiological processes. Nevertheless, Mn accumulation in the brain can cause a parkinsonian-like syndrome known as manganism. Unfortunately, the therapeutic options for this disease are scarce and of limited efficacy. For this reason, a great effort is being made to understand the cellular and molecular mechanisms involved in Mn toxicity in neuronal and glial cells. Even though evidence indicates that Mn activates autophagy in microglia, the consequences of this activation in cell death remain unknown. In this study, we demonstrated a key role of reactive oxygen species in Mn-induced damage in microglial cells. These species generated by Mn2+ induce lysosomal alterations, LMP, cathepsins release and cell death. Besides, we described for the first time the kinetic of Mn2+-induced autophagy in BV-2 microglial cells and its relevance to cell fate. We found that Mn promotes a time-dependent increase in LC3-II and p62 expression levels, suggesting autophagy activation. Possibly, cells trigger autophagy to neutralize the risks associated with lysosomal rupture. In addition, pre-treatment with both Rapamycin and Melatonin enhanced autophagy and retarded Mn2+ cytotoxicity. In summary, our results demonstrated that, despite the damage inflicted on a subset of lysosomes, the autophagic pathway plays a protective role in Mn-induced microglial cell death. We propose that 2 h Mn2+ exposure will not induce disturbances in the autophagic flux. However, as time passes, the accumulated damage inside the cell could trigger a dysfunction of this mechanism. These findings may represent a valuable contribution to future research concerning manganism therapies.


Assuntos
Autofagia/efeitos dos fármacos , Citoproteção , Manganês/toxicidade , Animais , Linhagem Celular , Citoproteção/efeitos dos fármacos , Proteínas de Fluorescência Verde/metabolismo , Cinética , Lisossomos/efeitos dos fármacos , Lisossomos/metabolismo , Camundongos , Modelos Biológicos , Espécies Reativas de Oxigênio/metabolismo
13.
Aquat Toxicol ; 224: 105484, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32380302

RESUMO

One of the consequences of global mining is the exposure of metals into the environment, caused by the rupture of tailings dams. Excess of metals, such as aluminum (Al) and manganese (Mn) can cause serious damage to fauna and flora. The presence of these metals, associated with the temperature increase that occurs nowadays can potentially increase biochemical and metabolic rates in plant tissues and may affect growth. Therefore, the objective of this work was to evaluate the toxicity of the metals Al and Mn into the biomass' growth of the macrophyte Ricciocarpos natans, under two temperatures (25 and 27 °C). R. natans individuals (n = 10 ± 0.5 cm wide) were exposed during 30 days to Al (1.5; 2.5 and 5.0 mg L-1) and Mn (0.7; 1.5 and 3.0 mg L-1) at temperatures and photoperiod-controlled germination chambers. Fresh macrophyte masses were determined gravimetrically to determine the kinetic growth using a logistic model. With that, it was noticed that the presence of Al interfered negatively in the increase of the R. natans biomass, mainly in the highest concentrations and at 27 °C. Mn, on the other hand, affected the increase in biomass, mainly in the highest concentration. As a result, the growth coefficients (µ) changed, being up to 4 times lower in the Al bioassays and up to 2 times higher than the control in the Mn bioassays. However, the dry R. natans biomass individuals that were exposed to the treatments was reduced when compared to the control, except for the lower concentration of Mn. These results contribute to the understanding of the environmental changes that can occur due to metals contained in mining tailings in aquatic ecosystems and the influence of global warming on the metabolic processes of the growth of aquatic macrophytes.


Assuntos
Alumínio/toxicidade , Temperatura Alta , Hydrocharitaceae/crescimento & desenvolvimento , Manganês/toxicidade , Rios/química , Poluentes Químicos da Água/toxicidade , Alumínio/metabolismo , Biomassa , Brasil , Ecossistema , Monitoramento Ambiental , Hydrocharitaceae/metabolismo , Manganês/metabolismo , Mineração , Poluentes Químicos da Água/metabolismo
14.
Toxicology ; 441: 152504, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32445656

RESUMO

Manganese (Mn) is essential for animal development and homeostasis. However, anthropogenic activities increase the concentration of Mn in the environment and lead to increased risk of exposure to high doses of the metal. Thus, this study aimed to evaluate the effect of high doses of Mn on the male reproductive system of swiss mice. The 22-day old mice were randomly sorted into four groups and exposed to 0 (control), 15, 30 and 60 mg of MnCl2/kg/day, via daily gavages for 45 days. After the exposure, the mice were euthanized and sperm, hormonal and oxidative stress endpoints were evaluated in the testis, seminal vesicle and hypothalamus. Exposure to Mn promoted weight reduction of androgen-dependent organs, as well as alteration of the levels of fecal androgenic metabolites. Sperm parameters were drastically affected in all treated groups and the antioxidants tested (catalase and glutathione-disulfide reductase activities, and non-protein thiols content) decreased in the testis. However, only a few endpoints were altered in the seminal vesicle. For the hypothalamus, there was a reduction in acetylcholinesterase activity, suggesting a neurotoxic potential of Mn. In conclusion, Mn may affect the hypothalamic-gonadal axis by impairing the development of androgen-dependent organs, testicular redox status and Leydig cell maturation.


Assuntos
Genitália Masculina/efeitos dos fármacos , Manganês/toxicidade , Reprodução/efeitos dos fármacos , Androgênios/análise , Animais , Fezes/química , Genitália Masculina/metabolismo , Células Intersticiais do Testículo/efeitos dos fármacos , Masculino , Camundongos , Estresse Oxidativo/efeitos dos fármacos , Motilidade Espermática/efeitos dos fármacos , Espermatogênese/efeitos dos fármacos , Testosterona/sangue
15.
Ecotoxicol Environ Saf ; 198: 110696, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32380306

RESUMO

Cleome viscosa L. is a promising species for the phytoremediation of Mn-contaminanted soil. To reveal the adaptive mechanisms of species to Mn stress, plant growth, Mn subcellular distribution, Mn chemical forms, and plant physiological and biochemical traits were characterized in plants grown under different concentrations of Mn2+ (0, 1000, 5000, 10000, 15000 and 20000 µM). The results showed that C. viscosa plant biomass initially increased and then decreased with rising Mn treatment concentration. C. viscosa plants can accumulate high levels of Mn in roots and leaves, and both the bioconcentration factor (BCF) and the translocation factor (TF) exhibited values higher than one. Mn was primarily retained in the cell wall and soluble fractions. Predominant chemical forms of Mn were pectate and protein, phosphates, and oxalates-integrated Mn. The activities of antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and the contents of proline, soluble sugar, and soluble protein initially increased and then decreased with enhancing Mn treatment concentration, whereas the malondialdehyde (MDA) content simultaneously displayed a gradual increase. Combined, these results indicate that C. viscosa can tolerate Mn-stress conditions by increasing antioxidant enzyme activities and non-enzymatic metabolites contents. In addition, Mn immobilization in the cell wall and soluble fractions, alongside the storage of Mn in low-activity chemical forms are further important mechanisms to cope with high environmental Mn concentration. This study reveals the adaptive mechanisms of plants to Mn stress, and provides a theoretical basis for the use of C. viscosa as a candidate phytoremediation plant for Mn-contaminated soil.


Assuntos
Cleome/fisiologia , Manganês/toxicidade , Poluentes do Solo/toxicidade , Antioxidantes/metabolismo , Biodegradação Ambiental , Biomassa , Catalase/metabolismo , Cleome/metabolismo , Malondialdeído/metabolismo , Manganês/metabolismo , Peroxidase/metabolismo , Peroxidases/metabolismo , Desenvolvimento Vegetal , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Solo/química , Poluentes do Solo/análise , Superóxido Dismutase/metabolismo
16.
Environ Toxicol Pharmacol ; 78: 103399, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32380377

RESUMO

Heavy metals enter the aquatic environment and accumulate within water sediments, but these metal-sediment interactions remain to be explored within toxicity studies. We developed an exposure model in mice that encapsulates the aquatic microenvironment of metals before exposure. Male and female C57/BL6 mice were exposed via their drinking water to manganese contaminated sediment (Sed_Mn) or to manganese without sediment interaction (Mn) for six weeks. Sediment interaction did not alter weekly manganese ingestion from water in males or females. We analyzed motor impairment, a common feature in manganese-induced Parkinsonism, using the beam traversal, cylinder, and accelerating rotarod tests. Sed_Mn mice performed better overall compared to Mn mice and males were more sensitive to manganese than females in both Sed_Mn and Mn treatment groups. Our study indicates that metal-sediment interactions may alter metal toxicity in mammals and introduces a new exposure model to test the toxicity of metal contaminants of drinking water.


Assuntos
Manganês/toxicidade , Transtornos Parkinsonianos/induzido quimicamente , Poluentes Químicos da Água/toxicidade , Animais , Comportamento Animal , Feminino , Sedimentos Geológicos , Masculino , Camundongos Endogâmicos C57BL , Caracteres Sexuais
17.
PLoS One ; 15(4): e0231634, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32298350

RESUMO

The WST-1 assay is the most common test to assess the in vitro cytotoxicity of chemicals. Tetrazolium-based assays can, however, be affected by the interference of tested chemicals, including carbon nanotubes or Mg particles. Here, we report a new interference of Mn materials with the WST-1 assay. Endothelial cells exposed to Mn particles (Mn alone or Fe-Mn alloy from 50 to 1600 µg/ml) were severely damaged according to the WST-1 assay, but not the ATP content assay. Subsequent experiments revealed that Mn particles interfere with the reduction of the tetrazolium salt to formazan. Therefore, the WST-1 assay is not suitable to evaluate the in vitro cytotoxicity of Mn-containing materials, and luminescence-based assays such as CellTiter-Glo® appear more appropriate.


Assuntos
Citotoxinas/toxicidade , Células Endoteliais/efeitos dos fármacos , Manganês/toxicidade , Sobrevivência Celular/efeitos dos fármacos , Células Endoteliais/citologia , Células Endoteliais da Veia Umbilical Humana , Humanos , Medições Luminescentes/métodos , Oxirredução , Sais de Tetrazólio/química , Testes de Toxicidade/métodos
18.
Sci Rep ; 10(1): 5206, 2020 03 23.
Artigo em Inglês | MEDLINE | ID: mdl-32251356

RESUMO

Groundwater through hand-operated tubewell (a type of water well) tapping is the main source of drinking water in Bangladesh. This study investigated iron and manganese concentration in groundwater across Jashore district-one of the worst arsenic contaminated area in Bangladesh. One working tubewell that had been tested previously for arsenic and marked safe (green) was selected from each unions of the district. Results revealed that approximately 73% and 87% of groundwater samples exceeded the limits for iron and manganese in Bangladesh drinking water, respectively. Additionally, spatial distribution of iron and manganese indicate that only 5% of the total surface area of groundwater is covered by safe level of iron and manganese. Human health risk due to ingestion of iron and manganese through drinking water was evaluated using hazard quotients (HQ) for adults and children. The result of the health risk assessment revealed that the non-carcinogenic health risks due to ingestion of iron (HQ up to 1.446 for adults and 0.590 for children) and manganese (HQ up to 2.459 for adults and 1.004 for children) contaminated groundwater are much higher among adults than children. On the basis of occurrences, spatial distribution and health risk assessment results, the area can be categorized as a high-risk zone for iron and manganese-related problems and needs special attention in order to protect public health of local residents.


Assuntos
Água Subterrânea/química , Ferro/toxicidade , Manganês/toxicidade , Medição de Risco , Abastecimento de Água , Poços de Água , Adulto , Arsênico/análise , Bangladesh , Criança , Humanos , Ferro/análise , Manganês/análise
19.
Infect Immun ; 88(6)2020 05 20.
Artigo em Inglês | MEDLINE | ID: mdl-32229614

RESUMO

Bacterial pathogens encounter a variety of nutritional environments in the human host, including nutrient metal restriction and overload. Uptake of manganese (Mn) is essential for Enterococcus faecalis growth and virulence; however, it is not known how this organism prevents Mn toxicity. In this study, we examine the role of the highly conserved MntE transporter in E. faecalis Mn homeostasis and virulence. We show that inactivation of mntE results in growth restriction in the presence of excess Mn, but not other metals, demonstrating its specific role in Mn detoxification. Upon growth in the presence of excess Mn, an mntE mutant accumulates intracellular Mn, iron (Fe), and magnesium (Mg), supporting a role for MntE in Mn and Fe export and a role for Mg in offsetting Mn toxicity. Growth of the mntE mutant in excess Fe also results in increased levels of intracellular Fe, but not Mn or Mg, providing further support for MntE in Fe efflux. Inactivation of mntE in the presence of excess iron also results in the upregulation of glycerol catabolic genes and enhanced biofilm growth, and addition of glycerol is sufficient to augment biofilm growth for both the mntE mutant and its wild-type parental strain, demonstrating that glycerol availability significantly enhances biofilm formation. Finally, we show that mntE contributes to colonization of the antibiotic-treated mouse gastrointestinal (GI) tract, suggesting that E. faecalis encounters excess Mn in this niche. Collectively, these findings demonstrate that the manganese exporter MntE plays a crucial role in E. faecalis metal homeostasis and virulence.


Assuntos
Proteínas de Bactérias/metabolismo , Enterococcus faecalis/metabolismo , Infecções por Bactérias Gram-Positivas/microbiologia , Manganês/metabolismo , Animais , Biofilmes , Transporte Biológico , Modelos Animais de Doenças , Trato Gastrointestinal/microbiologia , Homeostase , Espaço Intracelular/metabolismo , Manganês/toxicidade , Metais/metabolismo , Camundongos
20.
Exp Biol Med (Maywood) ; 245(9): 835-844, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32252555

RESUMO

IMPACT STATEMENT: Humans and animals are regularly exposed to toxic chemicals with subsequent adverse effects. Manganese exposure occurs via contaminated sources; over-exposure is associated with neuronal, hepatorenal dysfunction, etc. This work advances the field of natural chemopreventive agents by reporting evidence lacking in the literature on GA and ω-3-FA obtained primarily from the diet in protecting biological beings against toxic chemicals. Individually, GA and ω-3-FA exhibit various pharmacological effects. Our findings confirm the previous reports; however, we demonstrate the additional evidence for GA and ω-3-FA in abating toxic response incumbent on oxidative damage associated with manganese exposure. These findings further underscore the relevance of GA usage in food, cosmetics-pharmaceutical industries, and ω-3-FA as a safe supplement. Dietary supplements with GA and fish oil-rich in ω-3FA may be the potential natural therapy against hepatorenal injury in individuals inadvertently or occupationally exposed to manganese, thereby, promoting human and veterinary health outcomes.


Assuntos
Ácidos Graxos Ômega-3/farmacologia , Ácido Gálico/farmacologia , Inflamação/induzido quimicamente , Manganês/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Animais , Doença Hepática Induzida por Substâncias e Drogas/patologia , Inflamação/patologia , Nefropatias/induzido quimicamente , Nefropatias/patologia , Masculino , Distribuição Aleatória , Ratos , Ratos Wistar
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