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1.
Ecotoxicol Environ Saf ; 189: 110037, 2019 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-31812018

RESUMO

As an emerging class of nitrogenous disinfection by-products (N-DBPs), haloacetamides (HAcAms) have been widely detected in drinking water. Limited toxicity studies have shown an inconsistent toxicity of monoHAcAms, including CAcAm, BAcAm and IAcAm. In this study, the developmental toxicity of monoHAcAms was evaluated in embryo-larval stage of zebrafish. Embryos were exposed to one concentration of 2.50, 5.00, 10.0, 20.0, 40.0 and 80.0 mg/L monoHAcAms from 4 h post-fertilization (hpf) to 120 hpf. Multiple endpoints, including hatching rate, morphological abnormalities, mortality as well as locomotor behavior were assessed at specified stages (24, 48, 72, 96 and 120 hpf). Results showed that 80 mg/L CAcAm and 40 mg/L BAcAm significantly decreased the hatching rate, IAcAm decreased the hatching rate and delayed the hatching process in a concentration-dependent manner with an EC50 of 16.37 mg/L at 72 hpf. The frequency and severity order of morphological abnormalities increased with the raised exposure concentrations and prolonged exposure time, and the corresponding EC50 at 96 hpf were 21.10, 9.77 and 16.60 mg/L for CAcAm, BAcAm and IAcAm, respectively. MonoHAcAms exposure resulted in a time- and dose-dependent response in mortality and the calculated LC50 at 72 hpf were 38.44, 17.74 and 28.82 mg/L for CAcAm, BAcAm and IAcAm, respectively. Based on EC50 for morphological abnormalities and LC50, a toxicity rank order of BAcAm > IAcAm > CAcAm was observed. Different degrees of hyperactivity and hypoactivity were observed from locomotor behavior analysis in larvae from ≤10.0 mg/L monoHAcAms exposure groups. The light-dark periodic change was disappeared in larvae of 10.0 mg/L BAcAm exposure group. In summary, our study showed that monoHAcAms were developmentally toxic to zebrafish even at very low concentrations and BAcAm exerted higher toxicity than IAcAm and CAcAm. These results will further our understanding of the toxicity of HAcAms and its potential toxicological impact on human and ecological environment.

2.
Sci Total Environ ; 692: 1267-1275, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31539958

RESUMO

Humans are exposed to disinfection by-products (DBPs) mainly through drinking water ingestion and dermal contact. As an emerging class of nitrogenous DBPs (N-DBPs), haloacetamides (HAcAms) have been found to have significantly higher cytotoxicity than regulated DBPs. In this study, we investigated the cytotoxicity of HAcAms on two exposure pathway-related cell lines: human gastric epithelial GES-1 cells and immortalized keratinocytes HaCaT. Our results showed that the ranking order of cytotoxicity of 13 HAcAms was different between HaCaT and GES-1 cells. In addition, the 50% inhibitive concentration in HaCaT was 1.01-3.29 times that in GES-1. Further comparison among GES-1, HaCaT and CHO cell lines confirmed that different cell lines exhibited different sensitivity to the same compound. Importantly, HAcAms showed 5.83-7.13 × 104 times higher toxicity than the well-clarified DBP chloroform, clearly demonstrating the increased toxicity of HAcAms. Finally, using a novel high-content screening (HCS) analysis, we found that 39.29% of chlorinated HAcAms, 42.86% of brominated HAcAms and 16.07% of iodinated HAcAms significantly affected at least one of the cell-health parameters, such as nuclear size, membrane permeability, mitochondrial membrane potential, or cytochrome c release, in GES-1 or HaCaT cells. Thus, brominated HAcAms appear to have stronger effects under the sublethal exposure dose, possibly causing cytotoxicity via apoptosis. Together, our study provides new insights to the toxicity of HAcAms and a comprehensive toxicology dataset for health risk assessment.


Assuntos
Acetamidas/toxicidade , Desinfetantes/toxicidade , Poluentes Químicos da Água/toxicidade , Linhagem Celular , Desinfecção , Humanos , Testes de Toxicidade
3.
Artigo em Inglês | MEDLINE | ID: mdl-27235999

RESUMO

Color is an important property for food evaluation. Synthetic azo dyes are usually used in food product to obtain better appearance because of their stability and low cost. However, such dyes should be strictly controlled because of their potential threat to human health. A simple, rapid and sensitive method has been developed to determine orange II, allura red, and para red simultaneously by ion mobility spectrometry. The three dyes could be separated at the same time and the migration time of orange II, allura red, and para red are 12.070±0.010, 8.180±0.015, and 11.037±0.016ms, respectively. The effects of different parameters, such as pH, solvent, percentage of water, were investigated to establish the optimal condition. The detection limits were 0.1, 0.05, and 0.2µg/mL for orange II, allura red, and para red, respectively. The recoveries of the three azo dyes from jellies were all higher than 81%. The developed method is fast and accurate for the detection of the three synthetic dyes.


Assuntos
Compostos Azo/análise , Análise de Alimentos/métodos , Compostos Azo/química , Concentração de Íons de Hidrogênio , Limite de Detecção , Espectrometria de Massas
4.
Artigo em Inglês | MEDLINE | ID: mdl-26818744

RESUMO

Lead exposure can induce increased blood pressure. Several mechanisms have been proposed to explain lead-induced hypertension. Changes in angiotensinogen (AGT) expression levels or gene variants may also influence blood pressure. In this study, we hypothesized that AGT expression levels or gene variants contribute to lead-induced hypertension. A preliminary HEK293 cell model experiment was performed to analyze the association between AGT expression and lead exposure. In a population-based study, serum AGT level was measured in both lead-exposed and control populations. To further detect the influence of AGT gene single nucleotide polymorphisms (SNPs) in lead-induced hypertension, two SNPs (rs699 and rs4762) were genotyped in a case-control study including 219 lead-exposed subjects and 393 controls. Lead exposure caused an increase in AGT expression level in HEK 293 cell models (P < 0.001) compared to lead-free cells, and individuals exposed to lead had higher systolic and diastolic blood pressure (P < 0.001). Lead-exposed individuals had higher serum AGT levels compared to controls (P < 0.001). However, no association was found between AGT gene SNPs (rs699 and rs4762) and lead exposure. Nevertheless, the change in AGT expression level may play an important role in the development of lead-induced hypertension.


Assuntos
Angiotensinogênio/efeitos dos fármacos , Pressão Sanguínea/efeitos dos fármacos , Exposição Ambiental/efeitos adversos , Regulação da Expressão Gênica/efeitos dos fármacos , Células HEK293/efeitos dos fármacos , Hipertensão/etiologia , Chumbo/efeitos adversos , Angiotensinogênio/genética , Estudos de Casos e Controles , China , Feminino , Genótipo , Haplótipos , Humanos , Masculino , Mutagênicos/efeitos adversos , Polimorfismo de Nucleotídeo Único
5.
PLoS One ; 8(1): e54420, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23365666

RESUMO

Free extracellular DNA provides nutrition to bacteria and promotes bacterial evolution by inducing excessive mutagenesis of the genome. To understand the influence of extracellular DNA fragments on D. radiodurans, we investigated cell growth and survival after extracellular DNA or dNMPs treatment. The results showed that the extracellular DNA fragments inhibited the growth of D. radiodurans. Interestingly, dGMP, a DNA component, enhanced D. radiodurans tolerance to H(2)O(2) and gamma-radiation significantly. Further experiments indicated that extracellular dGMP stimulated the activity of one catalase (KatA, DR1998), and induced gene transcription including the extracellular nuclease (drb0067). When this only extracellular nuclease gene (drb0067) in D. radiodurans was deleted, the mutant strain showed more sensitive to H(2)O(2) and gamma-radiation than the wild type strain. These results suggest that DRB0067 plays an important role in oxidative stress resistance. Taken together, we proposed a new anti-oxidation mechanism in D. radiodurans. This mechanism acts to increase expression levels of DRB0067 which then secretes active nuclease to degrade extracellular DNA fragments. The extracellular nuclease has a two-fold benefit, creating more free dNTPs for further cell protection and the removal of extracellular DNA fragments.


Assuntos
Proteínas de Bactérias/genética , DNA Bacteriano , Deinococcus/enzimologia , Deinococcus/genética , Nucleotídeos de Desoxiguanina/farmacologia , Desoxirribonucleases/genética , Proteínas de Bactérias/metabolismo , Catalase/genética , Catalase/metabolismo , Deinococcus/efeitos dos fármacos , Deinococcus/efeitos da radiação , Desoxirribonucleases/metabolismo , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Escherichia coli/metabolismo , Escherichia coli/efeitos da radiação , Espaço Extracelular/metabolismo , Raios gama , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Regulação Bacteriana da Expressão Gênica/efeitos da radiação , Peróxido de Hidrogênio/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Estresse Oxidativo/efeitos da radiação , Tolerância a Radiação/efeitos dos fármacos , Transcrição Genética/efeitos dos fármacos , Transcrição Genética/efeitos da radiação
6.
PLoS One ; 7(4): e35057, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22523570

RESUMO

The high intracellular Mn/Fe ratio observed within the bacteria Deinococcus radiodurans may contribute to its remarkable resistance to environmental stresses. We isolated DR2539, a novel regulator of intracellular Mn/Fe homeostasis in D. radiodurans. Electrophoretic gel mobility shift assays (EMSAs) revealed that DR2539 binds specifically to the promoter of the manganese acquisition transporter (MntH) gene, and that DR0865, the only Fur homologue in D. radiodurans, cannot bind to the promoter of mntH, but it can bind to the promoter of another manganese acquisition transporter, MntABC. ß-galactosidase expression analysis indicated that DR2539 acts as a manganese- and iron-dependent transcriptional repressor. Further sequence alignment analysis revealed that DR2539 has evolved some special characteristics. Site-directed mutagenesis suggested that His98 plays an important role in the activities of DR2539, and further protein-DNA binding activity assays showed that the activity of H98Y mutants decreased dramatically relative to wild type DR2539. Our study suggests that D. radiodurans has evolved a very efficient manganese regulation mechanism that involves its high intracellular Mn/Fe ratio and permits resistance to extreme conditions.


Assuntos
Proteínas de Bactérias/genética , Proteínas de Transporte de Cátions/genética , Deinococcus/metabolismo , Proteínas Repressoras/fisiologia , Sequência de Aminoácidos , Proteínas de Bactérias/biossíntese , Proteínas de Transporte de Cátions/biossíntese , Deinococcus/genética , Compostos Ferrosos/metabolismo , Regulação Bacteriana da Expressão Gênica , Manganês/metabolismo , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Alinhamento de Sequência
7.
DNA Repair (Amst) ; 11(4): 349-56, 2012 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-22301370

RESUMO

The single-stranded DNA-specific nuclease RecJ is found in most bacteria where it is involved in the RecFOR double-stranded break (DSBs) repair pathway. DSBs repair mainly occurs via the RecFOR pathway in Deinococcus radiodurans, a well-known radiation-resistant bacterium. A recJ null mutant was constructed to investigate the role of recJ in D. radiodurans. recJ inactivation caused growth defects and sensitivity to high temperatures. However, the radiation resistance of the recJ mutant was only moderately decreased. The full-length D. radiodurans RecJ (DrRecJ) protein was expressed and purified to further characterize its biochemical properties. DrRecJ possessed a Mn(2+) concentration-dependent nuclease activity where the optimal Mn(2+) concentration was 0.1mM. DrRecJ had a similar activity profile after adding 10mM Mg(2+) to reactions with different Mn(2+) concentrations, indicating that Mn(2+) is a RecJ regulator. Escherichia coli RecJ has no activity on 5' ssDNA tails shorter than 6-nt, but DrRecJ could effectively degrade DNA with a 4-nt 5' ssDNA tail, suggesting that DrRecJ may have a wider range of DNA substrates. Moreover, SSB in D. radiodurans stimulated the DrRecJ exonuclease activity, whereas DdrB inhibited it and provided protection to ssDNA. Overall, our results indicate that recJ is a nonessential gene in D. radiodurans and that the activity of DrRecJ is regulated by Mn(2+) and SSB-DdrB.


Assuntos
Proteínas de Bactérias/metabolismo , Deinococcus/enzimologia , Exodesoxirribonucleases/metabolismo , Proteínas de Bactérias/genética , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/efeitos da radiação , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Sobrevivência Celular/efeitos da radiação , DNA de Cadeia Simples/metabolismo , Proteínas de Ligação a DNA/metabolismo , Deinococcus/citologia , Deinococcus/genética , Deinococcus/efeitos da radiação , Ativação Enzimática/efeitos dos fármacos , Ativação Enzimática/efeitos da radiação , Exodesoxirribonucleases/deficiência , Exodesoxirribonucleases/genética , Técnicas de Inativação de Genes , Manganês/farmacologia , Tolerância a Radiação/genética
9.
J Bacteriol ; 192(13): 3540-4, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20418393

RESUMO

Besides inhibiting RecA activity at the protein level, Deinococcus radiodurans RecX can suppress RecA induction at the transcriptional level. The regulation of RecX on recA induction is independent of RecA activity, and its N terminus is involved in this process.


Assuntos
Proteínas de Bactérias/metabolismo , Deinococcus/metabolismo , Recombinases Rec A/metabolismo , Proteínas de Bactérias/genética , Deinococcus/genética , Regulação Bacteriana da Expressão Gênica/genética , Regulação Bacteriana da Expressão Gênica/fisiologia , Recombinases Rec A/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa
10.
Microbiology ; 155(Pt 8): 2775-83, 2009 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19443548

RESUMO

A novel carotenoid 1,2-hydratase (CruF) responsible for the C-1',2' hydration of gamma-carotene was identified in the non-photosynthetic bacteria Deinococcus radiodurans R1 and Deinococcus geothermalis DSM 11300. Gene expression and disruption experiments demonstrated that dr0091 and dgeo2309 encode CruF in D. radiodurans and D. geothermalis, respectively. Their homologues were also found in the genomes of cyanobacteria, and exhibited little homology to the hydroxyneurosporene synthase (CrtC) proteins found mainly in photosynthetic bacteria. Phylogenetic analysis showed that CruF homologues form a separate family, which is evolutionarily distant from the known CrtC family.


Assuntos
Deinococcus/enzimologia , Hidroliases , Vias Biossintéticas , Carotenoides/metabolismo , DNA Bacteriano/análise , DNA Bacteriano/genética , DNA Bacteriano/metabolismo , Deinococcus/genética , Evolução Molecular , Deleção de Genes , Expressão Gênica , Genes Bacterianos , Hidroliases/genética , Hidroliases/metabolismo , Filogenia , Análise de Sequência de DNA , Homologia de Sequência do Ácido Nucleico
11.
Wei Sheng Wu Xue Bao ; 48(3): 317-22, 2008 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-18479057

RESUMO

RecA/Rad51/RadA recombinases are important recombination proteins with conserved functions. Studies on the enzymes have shown that members of RecA/Rad51/RadA family from bacteria, eukaryota, methanogens and halophilic archaea have UV inducibility. However, the UV inducibility of RadA homologues from hyperthermophilic archaea is controversial. We analyzed the UV inducibility of Sulfolobus tokodaii RadA by RT-PCR and immune assays. Comparing with the mock, the transcription and expression of the radA increased 2 and 1.5 folds respectively after UV irradiation at 100 J/m2, or 3 and 1 fold at 200 J/m2. These results demonstrated that S. tokodaii RadA could be induced after UV treatment. In addition, proteome induction analysis proved that there existed a DNA damage induction response in S. tokodaii, which further supported RadA inductility in this hyperthermophilic archaeon.


Assuntos
Proteínas Arqueais/genética , Proteínas de Ligação a DNA/genética , Regulação da Expressão Gênica em Archaea/efeitos da radiação , Sulfolobus/genética , Sulfolobus/efeitos da radiação , Anticorpos/análise , Anticorpos/imunologia , Proteínas Arqueais/imunologia , Proteínas Arqueais/isolamento & purificação , Western Blotting , Clonagem Molecular , Dano ao DNA , Proteínas de Ligação a DNA/imunologia , Proteínas de Ligação a DNA/isolamento & purificação , Eletroforese em Gel Bidimensional , Imunoensaio , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Raios Ultravioleta/efeitos adversos
12.
Sci China C Life Sci ; 51(1): 60-5, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18176792

RESUMO

ST0838 (designed stRad55B) is one of the four RadA paralogs (or Rad55 homologues) in the genome of the hyperthermophilic crenarchaeon Sulfolobus tokodaii. The gene is induced by UV irradiation, suggesting that it is involved in DNA recombinational repair in this organism. However, this protein could not be expressed normally in vitro. In this study, thermostable and soluble stRad55B was obtained by co-expression with S. tokodaii RadA (stRadA) in E. coli, and the enzymatic properties were examined. It was found that stRad55B bound ssDNA preferentially and had a very weak ATPase activity that was not stimulated by DNA. The recombinant protein inhibited the strand exchange activity promoted by stRadA, indicating that stRad55B might be an inhibitor to the homologous recombination in this archaeon. The results will be helpful for further functional and interaction analysis of RadA paralogs and for the understanding of the mechanism of recombinational repair in archaea.


Assuntos
Proteínas Arqueais/metabolismo , Proteínas de Ligação a DNA/metabolismo , Regulação da Expressão Gênica , Sulfolobus/metabolismo , Adenosina Trifosfatases/metabolismo , Proteínas Arqueais/genética , Proteínas Arqueais/isolamento & purificação , DNA/genética , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/isolamento & purificação , Regulação da Expressão Gênica/efeitos da radiação , Ligação Proteica , Desnaturação Proteica , Sulfolobus/genética , Sulfolobus/efeitos da radiação , Temperatura Ambiente
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