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1.
J Agric Food Chem ; 67(35): 9877-9884, 2019 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-31398030

RESUMO

Heavy metal contaminants and nutrient deficiencies in soil negatively affect crop growth and human health. The plant cadmium resistance (PCR) protein transports heavy metals. The abundance of PCR is correlated with that of cell number regulator (CNR) protein, and the two proteins have similar conserved domains. Hence, CNR might also participate in heavy metal transport. We isolated and analyzed TaCNR5 from wheat (Triticum aestivum). The expression level of TaCNR5 in the shoots of wheat increased under cadmium (Cd), zinc (Zn), or manganese (Mn) treatments. Transgenic plants expressing TaCNR5 showed enhanced tolerance to Zn and Mn. Overexpression of TaCNR5 in Arabidopsis increased Cd, Zn, and Mn translocation from roots to shoots. The concentrations of Zn and Mn in rice grains were increased in transgenic plants expressing TaCNR5. These roles of TaCNR5 in the translocation and distribution of heavy metals mean that it has potential as a genetic biofortification tool to fortify cereal grains with micronutrients.


Assuntos
Manganês/metabolismo , Oryza/genética , Oryza/metabolismo , Proteínas de Plantas/genética , Triticum/genética , Zinco/metabolismo , Arabidopsis/química , Arabidopsis/genética , Arabidopsis/metabolismo , Biofortificação , Transporte Biológico , Cádmio/análise , Cádmio/metabolismo , Manganês/análise , Oryza/química , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/química , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Triticum/química , Triticum/metabolismo , Zinco/análise
2.
Microbiol Res ; 226: 48-54, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31284944

RESUMO

The Burkholderia pseudomallei complex consists of six phylogenetically related Gram-negative bacterial species that include environmental saprophytes and mammalian pathogens. These microbes possess multiple type VI secretion systems (T6SS) that provide a fitness advantage in diverse niches by translocating effector molecules into prokaryotic and eukaryotic cells in a contact-dependent manner. Several recent studies have elucidated the regulation and function of T6SS-2, a novel contact-independent member of the T6SS family. Expression of the T6SS-2 gene cluster is repressed by OxyR, Zur and TctR and is activated by GvmR and reactive oxygen species (ROS). The last two genes of the T6SS-2 gene cluster encode a zincophore (TseZ) and a manganeseophore (TseM) that are exported into the extracellular milieu in a contact-independent fashion when microbes encounter oxidative stress. TseZ and TseM bind Zn2+ and Mn2+, respectively, and deliver them to bacteria where they provide protection against the lethal effects of ROS. The TonB-dependent transporters that interact with TseZ and TseM, and actively transport Zn2+ and Mn2+ across the outer membrane, have also been identified. Finally, T6SS-2 provides a contact-independent growth advantage in nutrient limited environments and is critical for virulence in Galleria mellonella larvae, but is dispensable for virulence in rodent models of infection.


Assuntos
Proteínas de Bactérias/genética , Burkholderia pseudomallei/genética , Burkholderia pseudomallei/metabolismo , Manganês/metabolismo , Sistemas de Secreção Tipo VI/genética , Sistemas de Secreção Tipo VI/metabolismo , Zinco/metabolismo , Animais , Proteínas de Bactérias/metabolismo , Burkholderia pseudomallei/classificação , Regulação Bacteriana da Expressão Gênica , Genes Reguladores/genética , Homeostase , Larva , Proteínas de Membrana Transportadoras/genética , Metiltransferases , Família Multigênica , Oxirredução , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo , Virulência/genética
3.
Sci Total Environ ; 690: 867-877, 2019 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-31302551

RESUMO

Fishery targeted species living in estuaries face multiple anthropogenic pressures including habitat contamination. However, trace metal concentrations in aquatic organisms can be highly variable, making it difficult to interpret accumulation responses. Understanding sources for metal accumulation in these organisms and their biokinetics is important for management of local fisheries and ensuring safety and quality of consumed seafood, particularly in urbanised areas. In this study, we exposed Australian sand clams, school prawns and sand whiting to a combination of cadmium (Cd), manganese (Mn) and zinc (Zn) radioisotopes 1) dissolved in seawater, 2) adsorbed to suspended sediment particles and 3) in radiolabelled food. Sand clams were sensitive to Cd, Mn and Zn uptake and accumulation from all sources because of their filter feeding physiology. Mean Cd and Zn assimilation efficiencies (AE) were higher in clams fed benthic diatoms (51, 43, 63% for Cd, Mn and Zn, respectively) than clams fed an algal flagellate species (22, 32, 33% for Cd, Mn and Zn, respectively). Metal uptake by prawns from seawater was low, whereas assimilation from diet was high (67, 59, 64% mean AEs from Cd, Mn and Zn, respectively). Sand whiting did not accumulate metals from seawater, even after concentrations were increased. Assimilation from diet (labelled prawns) was also low for sand whiting, particularly for Cd and Zn (11, 26, 14% mean AEs from Cd, Mn and Zn, respectively). These results may help explain the persistence of sand whiting in contaminated estuaries. Suspended sediment exposures showed that prawns and fish are less likely than clams to be negatively affected by disturbance events such as floods, which can bring metals into estuaries. The findings of this study have implications for fisheries management, both for protection and remediation of important habitats, and to ensure safe standards for seafood consumption by humans.


Assuntos
Organismos Aquáticos/metabolismo , Pesqueiros/estatística & dados numéricos , Metais/metabolismo , Poluentes Químicos da Água/metabolismo , Cádmio/metabolismo , Manganês/metabolismo , Zinco/metabolismo
4.
Ecotoxicol Environ Saf ; 181: 455-462, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31228821

RESUMO

Macleaya cordata is a perennial herb, a candidate phytoremediation plant with high biomass and manganese (Mn) tolerance. To study the mechanism underlying its Mn adaptability, Mn2+ at various concentrations (0, 1000, 5000, 10000, 15000, and 20000 µM) were applied to M. cordata to investigate the subcellular distribution and chemical forms of Mn, as well as the resulting physiological and biochemical changes by pot culture experiment under natural light in a greenhouse. According to our results, Mn level in M. cordata increased with exogenous Mn concentrations; and Mn contents in different tissues exhibited a leaf > root > stem pattern. Meanwhile, biomass and the level of photosynthetic pigments increased at lower Mn concentrations but declined as Mn concentration further ascended. Subcellular distribution analysis revealed that Mn was sequestered in cell wall and vacuole; in addition, it was incorporated into pectates and protein, phosphates, and oxalates. These findings revealed a possible effective strategy for M. cordata to reduce Mn mobility and toxicity. Moreover, a continuous boost in the level of malondialdehyde was observed with Mn gradient; whereas contents of soluble proteins and proline, and the activities of superoxide dismutase and peroxidase were initially increased and then dropped. Altogether, these results indicated that most Mn was trapped in the cell wall and soluble fractions in low toxicity forms such as pectates and protein, phosphates, and oxalates. These strategies, that is functioning cooperatively with the well-coordinated antioxidant defense systems and the non-enzymatic metabolites, confer strong resistance to Mn in M. cordata.


Assuntos
Adaptação Fisiológica , Poluentes Ambientais/metabolismo , Manganês/metabolismo , Papaveraceae/fisiologia , Antioxidantes/metabolismo , Biodegradação Ambiental , Biomassa , Parede Celular/metabolismo , Papaveraceae/enzimologia , Papaveraceae/metabolismo , Fotossíntese , Vacúolos/metabolismo
5.
Ecotoxicol Environ Saf ; 181: 18-25, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31154116

RESUMO

Effective phytoremediation of Mn contaminated soil requires the selection of a species with good manganese tolerance. Broussonetia papyrifera is an important economic plant and pioneer species, it could be well adapted to drought and saline-alkali environment. In order to understand the effect of Mn stress on B. papyrifera, the effects of different concentrations of Mn (0-50 mmol/L) stress on the growth, morphology, Mn tolerance and physiological indexes of the plant were explored. The results showed that the biomass, surface area, length, root volume, tips, forks, and crossings of B. papyrifera reached the maximum at the Mn concentration of 1 mmol/L. Mn content in the tissue and TF in plants increased with the increase of concentration, while the BCF increased first and then decreased, and the maximum BCF was 0.154 at 10 mmol/L. The accumulation of Mn lead to cell membrane lipid peroxidation, which increased toxic substances in plants, resulting in the increase of MDA and PRO, and affected the synthesis of chlorophyll. However, B. papyrifera could effectively alleviate oxidative stress by increasing the activities of antioxidant enzymes (SOD, POD, CAT), protein and soluble sugar. The results suggested that B. papyrifera had a good oxidative stress mechanism to Mn stress and could be used as candidates for remediation of pollution in mining areas.


Assuntos
Broussonetia/efeitos dos fármacos , Manganês/metabolismo , Poluentes do Solo/metabolismo , Solo/química , Estresse Fisiológico/efeitos dos fármacos , Antioxidantes/metabolismo , Biodegradação Ambiental , Biomassa , Broussonetia/fisiologia , Clorofila/metabolismo , Secas , Manganês/toxicidade , Poluentes do Solo/toxicidade
6.
Arch Anim Nutr ; 73(4): 324-337, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31192701

RESUMO

This experiment was conducted to evaluate the effects of different sources and levels of trace elements on growth performance, carcass composition and mineral excretion levels of broilers. In a completely randomised experimental design, 900 one-day-old male Ross-308 broilers were assigned to 5 treatments, with 6 replicates of 30 birds each. The control group (CITE) was fed with a basal diet containing regular inclusion levels of inorganic trace elements. Treatment groups were supplied with reduced levels (30% and 50% of the regular level) of inorganic (ITE) or organic trace elements (OTE), respectively. Groups 50% ITE, 30% OTE and 50% OTE diets had equivalent average daily gain (ADG), average daily feed intake (ADFI), feed to gain ratio (F/G ratio) and mortality rate compared with group CITE in any phase. However, compared with group CITE chicks in group 30% ITE have lower ADG and ADFI and higher F/G ratio. The carcass yields were not affected by dietary treatments. Compared with group CITE, in groups 30% ITE, 50% ITE, 30% OTE and 50% OTE the shear force values of the breast muscle were only 71.8%, 83.4%, 63.5% and 59.4% (p < 0.05), respectively. Birds received diets containing reduced levels of trace elements had diminished excretions of Mn and Zn throughout the entire period (p < 0.01). In conclusion, the reduced supplementation of trace elements had no or slightly negative impact on growth performance, carcass yield and meat quality, but decreased faecal mineral excretion. Moreover, the trace element supply as OTE played a limited role on performance and excretion and was only partly beneficial for animal performance in case the trace element supply was reduced to 30%.


Assuntos
Galinhas/fisiologia , Dieta/veterinária , Eliminação Intestinal , Minerais/metabolismo , Oligoelementos/metabolismo , Ração Animal/análise , Fenômenos Fisiológicos da Nutrição Animal/efeitos dos fármacos , Animais , Galinhas/crescimento & desenvolvimento , Cobre/administração & dosagem , Cobre/química , Cobre/metabolismo , Suplementos Nutricionais/análise , Relação Dose-Resposta a Droga , Fezes/química , Ferro/administração & dosagem , Ferro/química , Ferro/metabolismo , Masculino , Manganês/administração & dosagem , Manganês/química , Manganês/metabolismo , Carne/análise , Distribuição Aleatória , Oligoelementos/administração & dosagem , Zinco/administração & dosagem , Zinco/química , Zinco/metabolismo
7.
Molecules ; 24(7)2019 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-30934859

RESUMO

Artemisinins are widely used to treat Plasmodium infections due to their high clinical efficacy; however, the antimalarial mechanism of artemisinin remains unresolved. Mutations in P. falciparum ATPase6 (PfATP6), a sarcoplasmic endoplasmic reticulum Ca2+-transporting ATPase, are associated with increased tolerance to artemisinin. We utilized Saccharomyces cerevisiae as a model to examine the involvement of Pmr1p, a functional homolog of PfATP6, on the toxicity of artemisinin. Our analysis demonstrated that cells lacking Pmr1p are less susceptible to growth inhibition from artemisinin and its derivatives. No association between sensitivity to artemisinin and altered trafficking of the drug efflux pump Pdr5p, calcium homeostasis, or protein glycosylation was found in pmr1∆ yeast. Basal ROS levels are elevated in pmr1∆ yeast and artemisinin exposure does not enhance ROS accumulation. This is in contrast to WT cells that exhibit a significant increase in ROS production following treatment with artemisinin. Yeast deleted for PMR1 are known to accumulate excess manganese ions that can function as ROS-scavenging molecules, but no correlation between manganese content and artemisinin resistance was observed. We propose that loss of function mutations in Pmr1p in yeast cells and PfATP6 in P. falciparum are protective against artemisinin toxicity due to reduced intracellular oxidative damage.


Assuntos
Antimaláricos/farmacologia , Artemisininas/farmacologia , ATPases Transportadoras de Cálcio/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Transportadores de Cassetes de Ligação de ATP/metabolismo , Cálcio/metabolismo , Farmacorresistência Fúngica , Deleção de Genes , Manganês/metabolismo , Mutação , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/metabolismo , Leveduras/efeitos dos fármacos , Leveduras/metabolismo
8.
Dalton Trans ; 48(21): 7047-7061, 2019 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-30938390

RESUMO

Recent developments in Mn biology have added new physiological and pathophysiological roles of this essential metal ion to the already existing repertoire of indispensable biological roles of Mn ions. Notably, the discovery of Mn2+ specific transporters, maladies related to mutations in these transporters, and evidence of the role of labile Mn2+ species as anti-oxidants have initiated studies targeted at elucidating Mn ion regulation and pathways implicated in pathological conditions. Closely inter-linked with the quest for understanding metal ion homeostasis are basic questions like "How are metal ions installed in their correct biological addresses where they need to function?" and "Are dynamic changes in metal ion distribution functionally relevant?" These questions become more critical in the context of Mn2+ ions, which have inherently low binding affinities toward most ligands and hence would always face competing metal ions in the biological milieu. In the emerging context of functional roles of the labile Mn2+ ion pool, the development of chemical tools and techniques that can provide information on the location, distribution and dynamic changes in these parameters under physiological and pathophysiological conditions becomes imperative. In this frontier article, we discuss the challenges that had left Mn2+ ions lagging behind in the race for the development of chemical tools and recent approaches that addressed these challenges to develop tools and techniques that can illuminate Mn ions in living systems.


Assuntos
Manganês/metabolismo , Animais , Cátions Bivalentes , Membrana Celular/metabolismo , Corantes Fluorescentes/química , Homeostase , Humanos , Ligantes , Manganês/química , Imagem Óptica/métodos , Ligação Proteica , Transdução de Sinais
9.
Nat Commun ; 10(1): 1518, 2019 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-30944331

RESUMO

When migrating in vivo, cells are exposed to numerous conflicting signals: chemokines, repellents, extracellular matrix, growth factors. The roles of several of these molecules have been studied individually in vitro or in vivo, but we have yet to understand how cells integrate them. To start addressing this question, we used the cephalic neural crest as a model system and looked at the roles of its best examples of positive and negative signals: stromal-cell derived factor 1 (Sdf1/Cxcl12) and class3-Semaphorins. Here we show that Sdf1 and Sema3A antagonistically control cell-matrix adhesion via opposite effects on Rac1 activity at the single cell level. Directional migration at the population level emerges as a result of global Semaphorin-dependent confinement and broad activation of adhesion by Sdf1 in the context of a biased Fibronectin distribution. These results indicate that uneven in vivo topology renders the need for precise distribution of secreted signals mostly dispensable.


Assuntos
Movimento Celular/fisiologia , Junções Célula-Matriz/fisiologia , Crista Neural/citologia , Animais , Adesão Celular/efeitos dos fármacos , Adesão Celular/fisiologia , Comunicação Celular/fisiologia , Linhagem Celular , Forma Celular/efeitos dos fármacos , Extensões da Superfície Celular/efeitos dos fármacos , Junções Célula-Matriz/efeitos dos fármacos , Junções Célula-Matriz/metabolismo , Quimiocina CXCL12/metabolismo , Feminino , Fibronectinas/metabolismo , Masculino , Manganês/metabolismo , Camundongos , Proteínas do Tecido Nervoso/fisiologia , Crista Neural/efeitos dos fármacos , Crista Neural/metabolismo , Receptores CXCR4/metabolismo , Semaforinas/metabolismo , Xenopus laevis/embriologia , Proteínas rac1 de Ligação ao GTP/metabolismo
10.
Sci Total Environ ; 666: 1003-1010, 2019 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-30970467

RESUMO

Occupational manganese (Mn) exposure has been associated with cognitive and olfactory dysfunction; however, few studies have incorporated cumulative biomarkers of Mn exposure such as bone Mn (BnMn). Our goal was to assess the cross-sectional association between BnMn, blood Mn (BMn), and fingernail Mn (FMn) with cognitive and olfactory function among Mn-exposed workers. A transportable in vivo neutron activation analysis (IVNAA) system was designed and utilized to assess BnMn among 60 Chinese workers. BMn and FMn were measured using inductively coupled plasma mass spectrometry. Cognitive and olfactory function was assessed using Animal and Fruit Naming tests, World Health Organization/University of California-Los Angeles Auditory Verbal Learning Test (AVLT) and the University of Pennsylvania Smell Identification Test (UPSIT). Additional data were obtained via questionnaire. Regression models adjusted for age, education, factory of employment, and smoking status (UPSIT only), were used to assess the relationship between Mn biomarkers and test scores. In adjusted models, increasing BnMn was significantly associated with decreased performance on average AVLT scores [ß (95% confidence interval (CI)) = -0.65 (-1.21, -0.09)] and Animal Naming scores [ß (95% CI) = -1.54 (-3.00, -0.07)]. Increasing FMn was significantly associated with reduced performance measured by the average AVLT [ß (95% CI) = -0.35 (-0.70, -0.006)] and the difference in AVLT scores [ß (95% CI) = -0.40 (-0.77, -0.03)]. BMn was not significantly associated with any test scores; no significant associations were observed with Fruit Naming or UPSIT tests. BnMn and FMn, but not BMn, are associated with cognitive function in Mn-exposed workers. None of the biomarkers were significantly associated with olfactory function.


Assuntos
Cognição/efeitos dos fármacos , Aprendizagem/efeitos dos fármacos , Manganês/metabolismo , Exposição Ocupacional/efeitos adversos , Olfato/efeitos dos fármacos , Fala/efeitos dos fármacos , Adulto , Osso e Ossos/química , China , Estudos Transversais , Humanos , Masculino , Manganês/sangue , Pessoa de Meia-Idade , Unhas/química , Testes Neuropsicológicos
11.
J Biochem ; 166(2): 149-156, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-30825308

RESUMO

A cutinase from Saccharomonospora viridis AHK190, Cut190, can hydrolyze polyethylene terephthalate and has a unique feature that the activity and stability are regulated by Ca2+ binding. Our recent structural and functional analyses showed three Ca2+ binding sites and their respective roles. Here, we analysed the binding thermodynamics of Mn2+, Zn2+ and Mg2+ to Cut190 and their effects on the catalytic activity and thermal stability. The binding affinities of Mn2+ and Zn2+ were higher than that of Mg2+ and are all entropy driven with a binding stoichiometry of three, one and one for Zn2+, Mn2+ and Mg2+, respectively. The catalytic activity was measured in the presence of the respective metals, where the activity of 0.25 mM Mn2+ was comparable to that of 2.5 mM Ca2+. Our 3D Reference Interaction Site Model calculations suggested that all the ions exhibited a high occupancy rate for Site 2. Thus, Mn2+ and Mg2+ would most likely bind to Site 2 (contributes to stability) with high affinity, while to Sites 1 and 3 (contributes to activity) with low affinity. We elucidate the metal-dependent structural and functional properties of Cut190 and show the subtle balance on structure stability and flexibility is controlled by specific metal ions.


Assuntos
Actinobacteria/enzimologia , Cálcio/metabolismo , Hidrolases de Éster Carboxílico/metabolismo , Magnésio/metabolismo , Manganês/metabolismo , Zinco/metabolismo , Sítios de Ligação , Cálcio/química , Hidrolases de Éster Carboxílico/química , Hidrolases de Éster Carboxílico/genética , Estabilidade Enzimática , Magnésio/química , Manganês/química , Modelos Moleculares , Mutação , Termodinâmica , Zinco/química
12.
J Trace Elem Med Biol ; 53: 27-33, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30910203

RESUMO

Açaí pulp consumption has increased in Brazil and worldwide. Recently, a high average content of manganese (450 mg/kg) was observed in açaí pulp, raising the hypothesis of toxicological effects associated to its ingestion. However, the total concentration of an element does not reflect the real benefits and risks of consuming a food. In this context, the total, bioaccessible and bioavailable concentrations of Fe and Mn were assessed in 9 açaí pulps. Fe and Mn contents ranged from 27.6 to 73 and from 145 to 1197 mg kg-1, respectively. Fe and Mn bioaccessibilities represented from 29 to 40 and from 39 to 55% of total amounts. Fe bioavailabilities were lower than LOQ and those of Mn varied from 8 to 17% of total. A daily consumption of 100 g of açaí pulp exceeds by at least 1.5-fold the recommended Mn daily intakes for adults whereas poorly contributes to Fe intakes. Since the lowest Mn bioaccessible and bioavailable fraction corresponded to a Mn intake value higher than the tolerable upper intakes for children and that high amounts of Mn intake may impair Fe absorption, higher açaí consumption may be worrisome. Future nutritional, toxicological and speciation studies must be undertaken.


Assuntos
Digestão , Euterpe/química , Trato Gastrointestinal/metabolismo , Ferro/análise , Ferro/metabolismo , Manganês/análise , Manganês/metabolismo , Humanos , Espectrometria de Massas
13.
Mol Biotechnol ; 61(6): 385-399, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30919326

RESUMO

D-Tagatose is a ketohexose, which presents unique properties as a low-calorie functional sweetener possessing a sweet flavor profile similar to D-sucrose and having no aftertaste. Considered a generally recognized as safe (GRAS) substance by FAO/WHO, D-tagatose can be used as an intermediate for the synthesis of other optically active compounds as well as an additive in detergent, cosmetic, and pharmaceutical formulations. This study reports important features for L-arabinose isomerase (EC 5.3.1.4) (L-AI) use in industry. We describe arabinose (araA) gene virulence analysis, gene isolation, sequencing, cloning, and heterologous overexpression of L-AI from the food-grade GRAS bacterium Enterococcus faecium DBFIQ E36 in Escherichia coli and assess biochemical properties of this recombinant enzyme. Recombinant L-AI (rL-AI) was one-step purified to homogeneity by Ni2+-agarose resin affinity chromatography and biochemical characterization revealed low identity with both thermophilic and mesophilic L-AIs but high degree of conservation in residues involved in substrate recognition. Optimal conditions for rL-AI activity were 50 °C, pH 5.5, and 0.3 mM Mn2+, exhibiting a low cofactor concentration requirement and an acidic optimum pH. Half-life at 45 °C and 50 °C were 1427 h and 11 h, respectively, and 21.5 h and 39.5 h at pH 4.5 and 5.6, respectively, showing the high stability of the enzyme in the presence of a metallic cofactor. Bioconversion yield for D-tagatose biosynthesis was 45% at 50 °C after 48 h. These properties highlight the technological potential of E. faecium rL-AI as biocatalyst for D-tagatose production.


Assuntos
Aldose-Cetose Isomerases/metabolismo , Proteínas de Bactérias/metabolismo , Enterococcus faecium/enzimologia , Galactose/metabolismo , Hexoses/biossíntese , Aldose-Cetose Isomerases/genética , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Cátions Bivalentes , Clonagem Molecular , Coenzimas/metabolismo , Enterococcus faecium/genética , Ensaios Enzimáticos , Estabilidade Enzimática , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Vetores Genéticos/química , Vetores Genéticos/metabolismo , Temperatura Alta , Concentração de Íons de Hidrogênio , Cinética , Manganês/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Especificidade por Substrato
14.
Environ Sci Pollut Res Int ; 26(12): 12550-12562, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30848428

RESUMO

The brain is an important organ rich in mitochondria and more susceptible to oxidative stress. Tiron (sodium 4,5-dihydroxybenzene-1,3-disulfonate) is a potent antioxidant. This study aims to evaluate the effect of tiron on the impairment of brain mitochondria induced by exposure to radiation or manganese (Mn) toxicity. We assessed the capability of oxidative phosphorylation (OXPHOS) through determination of mitochondrial redox state, the activity of electron transport chain (ETC), and Krebs cycle as well as the level of adenosine triphosphate (ATP) production. Rats were exposed to 7 Gy of γ-rays or injected i.p. with manganese chloride (100 mg/kg), then treated with tiron (471 mg/kg) for 7 days. The results showed that tiron treatment revealed positive modulation on the mitochondrial redox state manifested by a marked decrease of hydrogen peroxide (H2O2), malondialdehyde (MDA), and total nitrate/nitrite (NOx) associated with a significant increase in total antioxidant capacity (TAC), glutathione (GSH) content, manganese superoxide dismutase (MnSOD), and glutathione peroxidase (GPx) activities. Moreover, tiron can increase the activity of ETC through preventing the depletion in the activity of mitochondrial complexes (I, II, III, and IV), an elevation of coenzyme Q10 (CoQ10) and cytochrome c (Cyt-c) levels. Additionally, tiron showed a noticeable increase in mitochondrial aconitase (mt-aconitase) activity as the major component of Krebs cycle to maintain a high level of ATP production. Tiron also can restore mitochondrial metal homeostasis through positive changes in the levels of calcium (Ca), iron (Fe), Mn, and copper (Cu). It can be concluded that tiron may be used as a good mitigating agent to attenuate the harmful effects on the brain through the inhibition of mitochondrial injury post-exposure to radiation or Mn toxicity.


Assuntos
Sal Dissódico do Ácido 1,2-Di-Hidroxibenzeno-3,5 Dissulfônico/metabolismo , Antioxidantes/metabolismo , Encéfalo/efeitos dos fármacos , Manganês/toxicidade , Animais , Encéfalo/fisiologia , Encéfalo/efeitos da radiação , Cobre/metabolismo , Raios gama , Glutationa/metabolismo , Glutationa Peroxidase/metabolismo , Peróxido de Hidrogênio/metabolismo , Masculino , Malondialdeído/metabolismo , Manganês/metabolismo , Mitocôndrias/metabolismo , Oxirredução , Fosforilação Oxidativa/efeitos dos fármacos , Fosforilação Oxidativa/efeitos da radiação , Estresse Oxidativo/efeitos dos fármacos , Ratos , Superóxido Dismutase/metabolismo
15.
Plant Sci ; 280: 97-109, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30824033

RESUMO

Manganese (Mn) toxicity is an important limiting factor for crop production in acidic soils. The basic helix-loop-helix (bHLH) transcription factors are involved in a variety of physiological processes. However, whether the bHLHs are involved in excess Mn stress response is largely unknown. Here, we report the functional characterization of ZmbHLH105 isolated from maize (Zea mays). The transcript levels of ZmbHLH105 were higher in leaves, and were markedly up-regulated under excess Mn stress in maize. ZmbHLH105 was localized in the nucleus with transactivation activity. Ectopic expression of ZmbHLH105 enhanced Mn tolerance in Saccharomyces cerevisiae cells. ZmbHLH105-overexpressing (OE) plants showed improved excess Mn tolerance in transgenic tobacco. The stress-tolerant phenotypes of these OE tobacco lines were accompanied by increases of key antioxidant enzyme activities, but decreases of reactive oxygen species (ROS) accumulations. Importantly, the OE plants had less increases than the wild-type in toxic Mn accumulation. Moreover, the transcript levels of Mn/Fe-related transporters in the OE lines displayed remarkable decreases compared with the wild-type under Mn stress, suggesting that ZmbHLH105 reduced Mn accumulation in plants largely by repressing expression of Mn/Fe-regulated transporter genes. Taken together, these results indicate that ZmbHLH105 confers improved Mn stress tolerance possibly by regulating antioxidant machinery-mediated ROS scavenging and expression of Mn/Fe-related transporters in plants. ZmbHLH105 could be exploited for developing drought-tolerant maize varieties.


Assuntos
Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/metabolismo , Zea mays/metabolismo , Antioxidantes/metabolismo , Regulação da Expressão Gênica de Plantas/genética , Regulação da Expressão Gênica de Plantas/fisiologia , Manganês/metabolismo , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas/genética , Tabaco/genética , Tabaco/metabolismo , Zea mays/genética
16.
Environ Sci Pollut Res Int ; 26(13): 12698-12708, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30877544

RESUMO

In this study, zero-valent iron (ZVI), nanoscale zero-valent iron (nZVI), Fe(II), and Mn(II) were investigated for their effects on mixotrophic denitrification coupled with cadmium (Cd(II)) adsorption process by Acinetobacter sp. SZ28. The removal rates of nitrate were 0.228 mg L-1 h-1 (ZVI), 0.133 mg L-1 h-1 (nZVI), 0.309 mg L-1 h-1 (Fe(II)) and 0.234 mg L-1 h-1 (Mn(II)), respectively. The Cd(II) removal efficiencies were 97.23% (ZVI), 95.79% (nZVI), 80.63% (Fe(II)), and 84.58% (Mn(II)), respectively. Meteorological chromatography analysis indicated that the characteristics of gas composition were different under different electron donor conditions. Moreover, characterization of bacterial metabolites produced by strain SZ28 under different conditions was analyzed. Sequence amplification identified the presence of the nitrate reductase gene (napA) and Mn(II)-oxide gene (cumA) in strain SZ28. The results of XRD and SEM indicated that ZVI, nZVI, Fe(II), and Mn(II) were oxidized into corresponding oxides. XPS spectra indicated that the Cd(II) was adsorbed onto biogenic precipitation.


Assuntos
Acinetobacter/metabolismo , Cádmio/metabolismo , Nitratos/metabolismo , Poluentes Químicos da Água/metabolismo , Purificação da Água/métodos , Acinetobacter/genética , Adsorção , Proteínas de Bactérias/genética , Cádmio/isolamento & purificação , Desnitrificação , Elétrons , Ferro/química , Ferro/metabolismo , Manganês/química , Manganês/metabolismo , Microscopia Eletrônica de Varredura , Nitrato Redutase/genética , Nitratos/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Difração de Raios X
17.
Regul Toxicol Pharmacol ; 104: 98-107, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30878574

RESUMO

INTRODUCTION: Manganese (Mn) is an essential element required for several biological systems. However, it is toxic in excessive accumulation. The toxic effects following Mn overexposure is well known in the CNS but other studies evaluating other target tissues remain scarce. OBJECTIVE: This study aimed to investigate sex-related differences in oxidative stress, metabolic parameters and Mn deposition in peripheral organs of Wistar rats exposed to subacute model of intoxication. METHODS: Male and female adult Wistar rats received 6 or 15 mg/kg of MnCl2, intraperitoneally, 5 days a week, for 4 consecutive weeks to mimic subacute intoxication. Control group received sterile saline 0,9% following the same protocol. After this period, the metal accumulation, oxidative stress, mitochondrial activity and histological parameters in cardiac muscle, kidney, lungs and liver were analysed. RESULTS: Increased Mn concentrations were found in all organs, especially kidneys. The cardiac muscle analysis revealed increased lipid peroxidation and decreasing of GSH levels in both doses of Mn in male and female rats. The increase of lipid peroxidation in liver was more evident in the male group, and there was a significant decrease of antioxidant capacity in males' kidney. Nevertheless, there was an increase of mitochondrial complex I activity in kidney of females and increase of mitochondrial complex II activity in male group. Histological analysis revealed morphological changes in hepatic and pulmonary tissue. CONCLUSION: Taken together, our results showed that subacute Mn exposure lead to significant metabolic, biochemical alterations especially in kidney and liver. Nevertheless, despite Mn deposition was virtually the same in the peripheral organs of male and female rats, it promotes different toxic effects between sexes.


Assuntos
Coração/efeitos dos fármacos , Rim/efeitos dos fármacos , Fígado/efeitos dos fármacos , Pulmão/efeitos dos fármacos , Manganês/farmacocinética , Manganês/toxicidade , Caracteres Sexuais , Animais , Relação Dose-Resposta a Droga , Feminino , Rim/metabolismo , Fígado/metabolismo , Pulmão/metabolismo , Masculino , Manganês/administração & dosagem , Manganês/metabolismo , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Oxirredução , Estresse Oxidativo/efeitos dos fármacos , Ratos , Ratos Wistar
18.
Artigo em Inglês | MEDLINE | ID: mdl-30818751

RESUMO

In recent years, biological purification technology has been widely developed in the process of iron and manganese removal from groundwater. The cultivation and maturation of the biological filter layer are key for biological iron and manganese removal processes. The time needed for maturation varies significantly with the water quality, filter and filter media conditions and operation parameters; sometimes it takes only one or two months, sometime more than half a year. In this paper, the feasibility of adopting an intermittent operation for the cultivation of biofilter was investigated with productive filters in a groundwater treatment plant, and the comparative test of the filter column was conducted. The results showed that the intermittent operation had little effect on the cultivation of the biofilter because dissolved oxygen would be gradually exhausted during the filter-suspension process, making the filter layer anaerobic, thus possibly inhibiting the growth and reproduction of IMOB (Iron and Manganese Oxidizing Bacteria). At the same time, the test shows that when the mature biological filter needs the suspension operation, the emptying method should be considered to avoid the destruction of the biological layer.


Assuntos
Água Subterrânea/microbiologia , Ferro/isolamento & purificação , Manganês/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Bactérias/crescimento & desenvolvimento , Bactérias/metabolismo , Biodegradação Ambiental , Filtração , Água Subterrânea/química , Ferro/metabolismo , Manganês/metabolismo , Oxirredução , Oxigênio/análise , Oxigênio/metabolismo , Poluentes Químicos da Água/metabolismo
19.
MBio ; 10(1)2019 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-30808698

RESUMO

Manganese (Mn) is an essential micronutrient critical for the pathogenesis of Staphylococcus aureus, a significant cause of human morbidity and mortality. Paradoxically, excess Mn is toxic; therefore, maintenance of intracellular Mn homeostasis is required for survival. Here we describe a Mn exporter in S. aureus, MntE, which is a member of the cation diffusion facilitator (CDF) protein family and conserved among Gram-positive pathogens. Upregulation of mntE transcription in response to excess Mn is dependent on the presence of MntR, a transcriptional repressor of the mntABC Mn uptake system. Inactivation of mntE or mntR leads to reduced growth in media supplemented with Mn, demonstrating MntE is required for detoxification of excess Mn. Inactivation of mntE results in elevated levels of intracellular Mn, but reduced intracellular iron (Fe) levels, supporting the hypothesis that MntE functions as a Mn efflux pump and Mn efflux influences Fe homeostasis. Strains inactivated for mntE are more sensitive to the oxidants NaOCl and paraquat, indicating Mn homeostasis is critical for resisting oxidative stress. Furthermore, mntE and mntR are required for full virulence of S. aureus during infection, suggesting S. aureus experiences Mn toxicity in vivo Combined, these data support a model in which MntR controls Mn homeostasis by balancing transcriptional repression of mntABC and induction of mntE, both of which are critical for S. aureus pathogenesis. Thus, Mn efflux contributes to bacterial survival and virulence during infection, establishing MntE as a potential antimicrobial target and expanding our understanding of Mn homeostasis.IMPORTANCE Manganese (Mn) is generally viewed as a critical nutrient that is beneficial to pathogenic bacteria due to its function as an enzymatic cofactor and its capability of acting as an antioxidant; yet paradoxically, high concentrations of this transition metal can be toxic. In this work, we demonstrate Staphylococcus aureus utilizes the cation diffusion facilitator (CDF) family protein MntE to alleviate Mn toxicity through efflux of excess Mn. Inactivation of mntE leads to a significant reduction in S. aureus resistance to oxidative stress and S. aureus -mediated mortality within a mouse model of systemic infection. These results highlight the importance of MntE-mediated Mn detoxification in intracellular Mn homeostasis, resistance to oxidative stress, and S. aureus virulence. Therefore, this establishes MntE as a potential target for development of anti-S. aureus therapeutics.


Assuntos
Proteínas de Transporte de Cátions/metabolismo , Manganês/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Animais , Proteínas de Transporte de Cátions/genética , Modelos Animais de Doenças , Regulação Bacteriana da Expressão Gênica , Homeostase , Ferro/metabolismo , Manganês/toxicidade , Camundongos Endogâmicos BALB C , Viabilidade Microbiana , Infecções Estafilocócicas/microbiologia , Infecções Estafilocócicas/patologia , Staphylococcus aureus/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Transcrição Genética , Virulência/efeitos dos fármacos
20.
Bioprocess Biosyst Eng ; 42(5): 741-752, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30783765

RESUMO

To accelerate extensive application of biological manganese removal technology, a pilot-scale biofilter for ammonia, iron and manganese removal was constructed to investigate the removal performance and microbial community profiles at different manganese concentrations. When manganese in influent increased from 1 to 10 mg/L, the pollutants were completely removed. Ammonia and iron was slightly changed along the filter depth, while manganese obviously increased. In 0 m of the filter depth, the abundance of Gallionella (iron oxidizing bacteria, IOB) increased, while Crenothrix (IOB) decreased. The abundance of Gallionella (manganese oxidizing bacteria, MnOB) in 0.4 and 0.8 m increased to 16.82% and 12.37%, respectively; and Crenothrix (MnOB) in 0.8 m increased to 19.95%, but decreased to 25.08% in 0.4 m. The abundance of ammonia oxidizing bacteria (AOB, Nitrosococcus) decreased in 0.4 and 0.8 m. The biofilter presented a high ability to remove manganese, and had a broad application prospect.


Assuntos
Amônia/metabolismo , Bactérias/crescimento & desenvolvimento , Ferro/metabolismo , Manganês/metabolismo , Microbiota , Purificação da Água/métodos , Filtração/métodos
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