scholarly journals Inactivation of Escherichia coli by Nanoparticulate Zerovalent Iron and Ferrous Ion

2010 ◽  
Vol 76 (22) ◽  
pp. 7668-7670 ◽  
Author(s):  
Jee Yeon Kim ◽  
Hee-Jin Park ◽  
Changha Lee ◽  
Kara L. Nelson ◽  
David L. Sedlak ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Reactive Oxygen Species ◽  
Cell Membrane ◽  
Respiratory Activity ◽  
Membrane Integrity ◽  
Ferrous Ion ◽  
Zerovalent Iron ◽  
Oxygen Species ◽  
Cell Membrane Integrity

ABSTRACT The mechanism of Escherichia coli inactivation by nanoparticulate zerovalent iron (nZVI) and Fe(II) was investigated using reactive oxygen species (ROS) quenchers and probes, an oxidative stress assay, and microscopic observations. Disruption of cell membrane integrity and respiratory activity was observed under deaerated conditions [more disruption by nZVI than Fe(II)], and OH or Fe(IV) appears to play a role.

The Protective Effects of Graphene Oxide Against the Stress from Organic Solvent by Covering Hela Cells

2019 ◽  
Vol 15 (4) ◽  
pp. 412-419 ◽  
Author(s):  
Haidi Gao ◽  
Jia-Hui Liu ◽  
Victoria Arantza León Anchustegui ◽  
Yulin Chang ◽  
Jichuan Zhang ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Graphene Oxide ◽  
Cell Membrane ◽  
Organic Solvent ◽  
Hela Cells ◽  
Membrane Integrity ◽  
Protective Role ◽  
Oxygen Species ◽  
Protective Effects ◽  
Cell Membrane Integrity

Background: In recent years, new nanomaterials have received great attention due to their widespread use in agriculture, food safety and pharmacy. Among them, graphene and graphene oxide (GO) are emerging as promising nanomaterials, which may have far-reaching effects on pharmacy and health. </P><P> Objective: In this paper, the living Hela cells were covered by GO (Hela@GO) and the cell viability, reactive oxygen species, membrane integrity and apoptosis of them were compared with the control Hela cells, especially under the stress from four kinds of organic solvent, including dimethyl sulphoxide, ethanol, acetone, and glycerin. </P><P> Results: It was suggested that the GO may protect cells by covering the cells, keeping their membrane integrity, reducing the ROS and decreasing the apoptosis. </P><P> Conclusion: GO has attracted the tremendous attention of their bioapplications. In this research, the GO adhered to Hela cells. It was observed that the Hela@GO grew well. Besides, it was suggested that the GO would play a protective role to Hela cells against four organic solvents, by maintaining the cell membrane integrity, reducing ROS, and inhibiting the apoptosis.

scholarly journals Thermal and Nonthermal Effects of Discontinuous Microwave Exposure (2.45 Gigahertz) on the Cell Membrane of Escherichia coli

2014 ◽  
Vol 80 (16) ◽  
pp. 4832-4841 ◽  
Author(s):  
Carole Rougier ◽  
Audrey Prorot ◽  
Philippe Chazal ◽  
Philippe Leveque ◽  
Patrick Leprat
Keyword(s):  
Escherichia Coli ◽  
Cell Membrane ◽  
Cell Membranes ◽  
Membrane Integrity ◽  
Threshold Effect ◽  
Cell Suspensions ◽  
Conventional Heating ◽  
Content Type ◽  
Cell Membrane Integrity ◽  
Average Temperature

ABSTRACTThe aim of this study was to investigate the effects on the cell membranes ofEscherichia coliof 2.45-GHz microwave (MW) treatment under various conditions with an average temperature of the cell suspension maintained at 37°C in order to examine the possible thermal versus nonthermal effects of short-duration MW exposure. To this purpose, microwave irradiation of bacteria was performed under carefully defined and controlled parameters, resulting in a discontinuous MW exposure in order to maintain the average temperature of the bacterial cell suspensions at 37°C.Escherichia colicells were exposed to 200- to 2,000-W discontinuous microwave (DW) treatments for different periods of time. For each experiment, conventional heating (CH) in a water bath at 37°C was performed as a control. The effects of DW exposure on cell membranes was investigated using flow cytometry (FCM), after propidium iodide (PI) staining of cells, in addition to the assessment of intracellular protein release in bacterial suspensions. No effect was detected when bacteria were exposed to conventional heating or 200 W, whereas cell membrane integrity was slightly altered when cell suspensions were subjected to powers ranging from 400 to 2,000 W. Thermal characterization suggested that the temperature reached by the microwave-exposed samples for the contact time studied was not high enough to explain the measured modifications of cell membrane integrity. Because the results indicated that the cell response is power dependent, the hypothesis of a specific electromagnetic threshold effect, probably related to the temperature increase, can be advanced.

A compensatory increase in trehalose synthesis in response to desiccation stress in Saccharomyces cerevisiae cells lacking the heat shock protein Hsp12p

2008 ◽  
Vol 54 (7) ◽  
pp. 559-568 ◽  
Author(s):  
Vanessa J. Shamrock ◽  
George G. Lindsey
Keyword(s):  
Oxidative Stress ◽  
Reactive Oxygen Species ◽  
Flow Cytometry ◽  
Type Strain ◽  
Wild Type Strain ◽  
Membrane Integrity ◽  
Oxygen Species ◽  
Wild Type ◽  
Plasma Membrane Integrity ◽  
Trehalose Synthesis

The effect of HSP12 deletion on the response of yeast to desiccation was investigated. The Δhsp12 strain was found to be more desiccation tolerant than the wild-type strain. Furthermore, the increased intracellular trehalose levels in the Δhsp12 strain suggested that this strain compensated for the lack of Hsp12p synthesis by increasing trehalose synthesis, which facilitated increased desiccation tolerance. Results obtained from flow cytometry using the membrane exclusion dye propidium iodide suggested that Hsp12p helped maintain plasma membrane integrity during desiccation. Analysis of the oxidative loads experienced by the wild-type and Δhsp12 strains showed that during mid-exponential phase, the increased trehalose levels present in the Δhsp12 cells resulted in increased protection of these cells against reactive oxygen species compared with wild-type cells. During stationary phase, lower levels of reactive oxygen species reduction by reduced glutathione was enhanced in the wild-type strain, which displayed lower intracellular trehalose concentrations. Comparison of the tolerance of the wild-type and Δhsp12 strains with applied oxidative stress showed that the Δhsp12 strain was more tolerant to exogenously applied H2O2, which we attributed to the higher intracellular trehalose concentration. Flow cytometry demonstrated that Hsp12p played a role in maintaining plasma membrane integrity during applied oxidative stress.

Structure, mechanism and ensemble formation of the alkylhydroperoxide reductase subunits AhpC and AhpF fromEscherichia coli

2014 ◽  
Vol 70 (11) ◽  
pp. 2848-2862 ◽  
Author(s):  
Phat Vinh Dip ◽  
Neelagandan Kamariah ◽  
Malathy Sony Subramanian Manimekalai ◽  
Wilson Nartey ◽  
Asha Manikkoth Balakrishna ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Reactive Oxygen Species ◽  
Catalytic Activity ◽  
Mechanistic Model ◽  
Titration Calorimetry ◽  
Oxygen Species ◽  
X Ray ◽  
X Ray Scattering ◽  
Ring Solution

Hydroperoxides are reactive oxygen species (ROS) that are toxic to all cells and must be converted into the corresponding alcohols to alleviate oxidative stress. InEscherichia coli, the enzyme primarily responsible for this reaction is alkylhydroperoxide reductase (AhpR). Here, the crystal structures of both of the subunits ofEcAhpR,EcAhpF (57 kDa) andEcAhpC (21 kDa), have been solved. TheEcAhpF structures (2.0 and 2.65 Å resolution) reveal an open and elongated conformation, while that ofEcAhpC (3.3 Å resolution) forms a decameric ring. Solution X-ray scattering analysis ofEcAhpF unravels the flexibility of its N-terminal domain, and its binding toEcAhpC was demonstrated by isothermal titration calorimetry. These studies suggest a novel overall mechanistic model of AhpR as a hydroperoxide scavenger, in which the dimeric, extended AhpF prefers complex formation with the AhpC ring to accelerate the catalytic activity and thus to increase the chance of rescuing the cell from ROS.

Detecting reactive oxygen species in free-living symbiotic dinoflagellates exposed to nanoparticles v1

2021 ◽  
Author(s):  
Liza M M Roger ◽  
Nastassja Lewinski
Keyword(s):  
Oxidative Stress ◽  
Reactive Oxygen Species ◽  
Cell Membrane ◽  
Fluorescent Probe ◽  
Cellular Systems ◽  
Oxygen Species ◽  
Free Living ◽  
Fluorescent Compound ◽  
H2o2 Formation ◽  
Symbiotic Dinoflagellates

2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) is a popular fluorescent probe for the detection of oxidative stress in cells. Since the probe can be prone to auto-oxidation, carboxy-2',7'-dichlorodihydrofluorescein-diacetate (carboxy-H2DCF-DA) which is more stable and easily penetrates cell membranes is often reported in the literature instead. Upon crossing the cell membrane, esterases hydrolyse DCFH-DA to DCFH, which remains trapped within cells. The oxidation of DCFH yields DCF, a fluorescent compound which can be measured using excitation/emission wavelengths of 485-495/520-530 nm. Due to several cases of interference when used in cellular systems, DCFH-DA is a general marker of the cellular oxidative stress rather than a specific indicator H2O2 formation or other ROS.

scholarly journals Oxidative stress in pregnancy and reproduction

2016 ◽  
Vol 9 (3) ◽  
pp. 113-116 ◽  
Author(s):  
Kate Duhig ◽  
Lucy C Chappell ◽  
Andrew H Shennan
Keyword(s):  
Oxidative Stress ◽  
Reactive Oxygen Species ◽  
Preterm Labour ◽  
Membrane Integrity ◽  
Cellular Membrane ◽  
Cellular Damage ◽  
Oxygen Species ◽  
Overwhelming Evidence ◽  
Excess Reactive Oxygen Species ◽  
In Pregnancy

Oxidative stress is implicated in the pathophysiology of many reproductive complications including infertility, miscarriage, pre-eclampsia, fetal growth restriction and preterm labour. The presence of excess reactive oxygen species can lead to cellular damage of deoxyribonucleic acids, lipids and proteins. Antioxidants protect cells from peroxidation reactions, limiting cellular damage and helping to maintain cellular membrane integrity. There is overwhelming evidence for oxidative stress causing harm in reproduction. However, there is sparse evidence that supplementation with commonly used antioxidants (mostly vitamins C and E) makes any difference in overcoming oxidative stress or reversing disease processes. There may be potential for antioxidant therapy to ameliorate or prevent disease, but this requires a thorough understanding of the mechanism of action and specificity of currently used antioxidants.

Identification of FtpA, a Dps-like protein involved in anti-oxidative stress and virulence in Actinobacillus pleuropneumoniae

2021 ◽  
Author(s):  
Hao Tang ◽  
Qiuhong Zhang ◽  
Weiyao Han ◽  
Zhenyue Wang ◽  
Siqi Pang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Reactive Oxygen Species ◽  
Fenton Reaction ◽  
Actinobacillus Pleuropneumoniae ◽  
Bacterial Pathogenesis ◽  
Oxygen Species ◽  
Wild Type ◽  
Aerobic Conditions

Bacteria have evolved a variety of enzymes to eliminate endogenous or host-derived oxidative stress factors. The Dps protein, first identified in Escherichia coli , contains a ferroxidase center and protects bacteria from reactive oxygen species damage. There is a lack of knowledge of the role of Dps-like proteins in bacterial pathogenesis. Actinobacillus pleuropneumoniae causes pleuropneumonia, a respiratory disease of swine. The A. pleuropneumoniae ftpA gene is up-regulated during a shift to anaerobiosis, in biofilms and, as found in this study, also by H 2 O 2 . An A. pleuropneumoniae ftpA deletion mutant (△ ftpA ) had increased H 2 O 2 sensitivity, less intracellular viability in macrophages, and decreased virulence in a mouse infection model. Expression of ftpA in an E. coli dps mutant restored wild-type resistance to H 2 O 2 . FtpA possesses a conserved ferritin domain containing a ferroxidase site. Recombinant rFtpA bound and oxidized Fe 2+ reversibly. Under aerobic conditions, compared with the wild-type strain, the viability of an △ ftpA mutant was reduced after extended culture, transition from anaerobic to aerobic conditions, and upon supplementation with Fenton reaction substrates. Under anaerobic conditions, additional H 2 O 2 resulted in a more severe growth defect of △ ftpA than under aerobic conditions. Therefore, by oxidizing and mineralizing Fe 2+ , FtpA alleviates oxidative damage mediated by intracellular Fenton reactions. Furthermore, by mutational analysis, two residues were confirmed to be critical for Fe 2+ binding and oxidization, as well as for A. pleuropneumoniae H 2 O 2 resistance. Taken together, this study demonstrates that A. pleuropneumoniae FtpA is a Dps-like protein, playing critical roles in oxidative stress resistance and virulence. IMPORTANCE As a ferroxidase, Dps of Escherichia coli can protect bacteria from reactive oxygen species damage, but its role in bacterial pathogenesis has received little attention. In this study, FtpA of the swine respiratory pathogen A. pleuropneumoniae was identified as a new Dps-like protein. It facilitated A. pleuropneumoniae resistance to H 2 O 2 , survival in macrophages, and infection in vivo . FtpA could bind and oxidize Fe 2+ through two important residues in its ferroxidase site and protected the bacteria from oxidative damage mediated by the intracellular Fenton reaction. These findings provide new insights into the role of the FtpA-based antioxidant system in the pathogenesis of A. pleuropneumoniae , and the conserved Fe 2+ binding ligands in Dps/FtpA provide novel drug target candidates for disease prevention.

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