Peroxide Resistance Research Articles

Hematological changes and resistance of erythrocytes of crimean horses in response to 32 km races

Aim. The aim of the present study was to investigate the alterations of some hematological parameters (hae- matocrit (HCT), haemoglobin concentration (HGB), the count of red blood cells (RBC), mean corpuscular hemoglobin concentration (MCHC), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), red cell distribution width (RDW), as well as resistance of erythrocytes to urea and hydrogen peroxide in horses after 32 km endurance race. Methods. Seven horses from Crimea region (Bilohirsk, Crimean region) were involved in this study. Haematological parameters (haematocrit (HCT), haemoglobin concentration (HGB), the count of red blood cells (RBC), mean corpuscular hemoglobin concentration (MCHC), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), red cell distribution width (RDW)) were determined with use of hematological and biochemical methods. Blood samples have been investigated by centrifugation at 3,000 g for 15 min. The peroxide and osmotic resistance of erythrocytes were determined spectrophoto- metrically at 540 nm by monitoring the rate of erythrocytes disintegration by hydrogen peroxide. Endurance h orses used in this study are trained and conditioned to perform over long distances at moderate speeds. The prolonged exercises were used in endurance race. The walk about 3 km/h for 20 min, the trot about 7 km/h for 15 min, and the canter about 5 km/h for 15 min) and the walk about 1 km were repeated for 1 h (phase I); rest in an outdoor paddock without access to water for 30 min. And phase II: the walk about 3 km/h for 20 min, the trot about 7 km/h for 15 min, and the canter about 5 km/h for 15 min) and the walk about 1 km was repeated for 1 h. Results. The results of the present study showed that adequate endurance race of low intensity could im- prove oxygen-dependent respiratory function in horses from Crimean region. Furthermore, the non-signifi cant increase of red blood cells indices in endurance horses indicate about good athletic level after 32 km endur- ance ride. Statistically signifi cant differences in the percentage of hemolyzed erythrocytes between pre- and post-ride period were observed and thereby signifying an oxidative stress-dependent impairment of erythrocyte stability. Conclusions. The haematological changes caused by various physical efforts refl ect changes in the functions of different systems and can be used for health control and diagnosis of diseases. It also allow the evaluating the level of sport performance, the accuracy of training, and physiological condition of horses.

Reaction of PerR with Molecular Oxygen May Assist H2O2 Sensing in Anaerobes.

PerR is the peroxide resistance regulator found in several pathogenic bacteria and governs their resistance to peroxide stress by inducing enzymes that destroy peroxides. However, it has recently been implicated as a key component of the aerotolerance in several facultative or strict anaerobes, including the highly pathogenic Staphylococcus aureus. By combining (18)O labeling studies to ESI- and MALDI-TOF MS detection and EMSA experiments, we demonstrate that the active form of PerR reacts with dioxygen, which leads ultimately to disruption of the PerR/DNA complex and is thus physiologically meaningful. Moreover, we show that the presence of O2 assists PerR sensing of H2O2, another feature likely to be important for anaerobic organisms. These results allow one to envisage different scenarios for the response of anaerobes to air exposure.

Experimental investigation of some systemic effects of nitric oxide inhalation

The goal of this work was to study the influence of nitric oxide inhalation on parameters of blood proand antioxidant systems in rats under both an intact condition and experimental thermal injury. We studied 40 Wistar rats that were divided into four equal groups. The intact group was subjected to no manipulation exnept a single blood sampling, main group I was subjected to inhalation of a air mixture containing 20 ppm of nitric oxide for 10 days, the control group was subjected to thermal injury and conventional treatment, and main group II was subjected to thermal injury and daily inhalation of nitric oxide (20 ppm) for 10 days. We studied the intensity of lipid peroxidation in the blood plasma, the total antioxidant activity, the peroxide resistance of erythrocytes, the level of malondialdehyde in the blood plasma and erythrocytes, and the activity of superoxide dismutase. It was shown that daily inhalations of a mixture containing a low concentration of nitric oxide (20 ppm) modified blood oxidative metabolism in healthy and burned rats. We hypothesized that the activation of lipid peroxidation in erythrocytes accompanied by a pronounced increase in the catalytic activity of superoxide dismutase is a unified response of healthy and burned rats to exogenous nitric oxide exposure. We also observed a moderate prooxidant effect in the blood plasma of healthy animals comparable to that in the erythrocytes of these rats. In the case of thermal injury, oxidative stress tended to be corrected after the end of the course of inhalation.

The three catalases in Deinococcus radiodurans: Only two show catalase activity

Deinococcus radiodurans, which is extremely resistant to ionizing radiation and oxidative stress, is known to have three catalases (DR1998, DRA0146, and DRA0259). In this study, to investigate the role of each catalase, we constructed catalase mutants (Δdr1998, ΔdrA0146, and ΔdrA0259) of D. radiodurans. Of the three mutants, Δdr1998 exhibited the greatest decrease in hydrogen peroxide (H2O2) resistance and the highest increase in intracellular reactive oxygen species (ROS) levels following H2O2 treatments, whereas ΔdrA0146 showed no change in its H2O2 resistance or ROS level. Catalase activity was not attenuated in ΔdrA0146, and none of the three bands detected in an in-gel catalase activity assay disappeared in ΔdrA0146. The purified His-tagged recombinant DRA0146 did not show catalase activity. In addition, the phylogenetic analysis of the deinococcal catalases revealed that the DR1998-type catalase is common in the genus Deinococcus, but the DRA0146-type catalase was found in only 4 of 23 Deinococcus species. Taken together, these results indicate that DR1998 plays a critical role in the anti-oxidative system of D. radiodurans by detoxifying H2O2, but DRA0146 does not have catalase activity and is not involved in the resistance to H2O2 stress.

The Cytochrome bd Oxidase of Porphyromonas gingivalis Contributes to Oxidative Stress Resistance and Dioxygen Tolerance.

Porphyromonas gingivalis is an etiologic agent of periodontal disease in humans. The disease is associated with the formation of a mixed oral biofilm which is exposed to oxygen and environmental stress, such as oxidative stress. To investigate possible roles for cytochrome bd oxidase in the growth and persistence of this anaerobic bacterium inside the oral biofilm, mutant strains deficient in cytochrome bd oxidase activity were characterized. This study demonstrated that the cytochrome bd oxidase of Porphyromonas gingivalis, encoded by cydAB, was able to catalyse O2 consumption and was involved in peroxide and superoxide resistance, and dioxygen tolerance.

The complex genetic and molecular basis of a model quantitative trait.

Quantitative traits are often influenced by many loci with small effects. Identifying most of these loci and resolving them to specific genes or genetic variants is challenging. Yet, achieving such a detailed understanding of quantitative traits is important, as it can improve our knowledge of the genetic and molecular basis of heritable phenotypic variation. In this study, we use a genetic mapping strategy that involves recurrent backcrossing with phenotypic selection to obtain new insights into an ecologically, industrially, and medically relevant quantitative trait-tolerance of oxidative stress, as measured based on resistance to hydrogen peroxide. We examine the genetic basis of hydrogen peroxide resistance in three related yeast crosses and detect 64 distinct genomic loci that likely influence the trait. By precisely resolving or cloning a number of these loci, we demonstrate that a broad spectrum of cellular processes contribute to hydrogen peroxide resistance, including DNA repair, scavenging of reactive oxygen species, stress-induced MAPK signaling, translation, and water transport. Consistent with the complex genetic and molecular basis of hydrogen peroxide resistance, we show two examples where multiple distinct causal genetic variants underlie what appears to be a single locus. Our results improve understanding of the genetic and molecular basis of a highly complex, model quantitative trait.

The Candida albicans Histone Acetyltransferase Hat1 Regulates Stress Resistance and Virulence via Distinct Chromatin Assembly Pathways.

Human fungal pathogens like Candida albicans respond to host immune surveillance by rapidly adapting their transcriptional programs. Chromatin assembly factors are involved in the regulation of stress genes by modulating the histone density at these loci. Here, we report a novel role for the chromatin assembly-associated histone acetyltransferase complex NuB4 in regulating oxidative stress resistance, antifungal drug tolerance and virulence in C. albicans. Strikingly, depletion of the NuB4 catalytic subunit, the histone acetyltransferase Hat1, markedly increases resistance to oxidative stress and tolerance to azole antifungals. Hydrogen peroxide resistance in cells lacking Hat1 results from higher induction rates of oxidative stress gene expression, accompanied by reduced histone density as well as subsequent increased RNA polymerase recruitment. Furthermore, hat1Δ/Δ cells, despite showing growth defects in vitro, display reduced susceptibility to reactive oxygen-mediated killing by innate immune cells. Thus, clearance from infected mice is delayed although cells lacking Hat1 are severely compromised in killing the host. Interestingly, increased oxidative stress resistance and azole tolerance are phenocopied by the loss of histone chaperone complexes CAF-1 and HIR, respectively, suggesting a central role for NuB4 in the delivery of histones destined for chromatin assembly via distinct pathways. Remarkably, the oxidative stress phenotype of hat1Δ/Δ cells is a species-specific trait only found in C. albicans and members of the CTG clade. The reduced azole susceptibility appears to be conserved in a wider range of fungi. Thus, our work demonstrates how highly conserved chromatin assembly pathways can acquire new functions in pathogenic fungi during coevolution with the host.

INDICATORS OF OXIDATIVE STRESS AND RESISTANCE OF ERYTHROCYTES IN PATIENTS WITH CHRONIC KIDNEY DISEASE STAGE VD DEPENDING ON MODALITY OF RENAL REPLACEMENT THERAPY

The object was to study the effect of oxidative factors and methods of renal replacement therapy (RRT) on indices of oxidative stress (OS) and resistance cells in blood in patients with chronic kidney disease stage V(CKD VD) and anemic syndrome.
 Material and methods. The study involved 47 patients with CKD VD: 14patients were treated by hemodiafiltration (HDF), 14 patients by hemodialysis (HD) and 19 patients by peritoneal dialysis (PD). The severity ofanemia was assessed according to the KDIGO (2012) criteria. The control group consisted of30 healthy people of the same age and sex. Along with the standard diagnostic methods, we defined the content of malonic dialdehyde in serum (MDAs) and in erythrocytes (MDAe), the content of ceruloplasmin (CPs), transferrin (TRs) and SH - groups in the blood serum, the index of the OS (IOS), catalase activity in serum (CTs), glucose - 6 - phosphate dehydrogenase (G - 6 - PDHe) and total peroxidase activity (TPA) in erythrocyte, osmotic (OR) and peroxide resistance (PR) of red blood cells and erythrocyte membrane permeability (EMP). Statistical analysis was performed using the programs Microsoft Excel 5,0 and MedStat.
 Results. It has been stated that in the CKD VD patients agains the rates in control group the MDAs content increased by 3.3 times and MDAe - 1.2 times, TRs content reduced by 34%, SH - groups - by 31%, TPAe - by 41% and G - 6 - FDGe - by 58%, marcers of OR by 30%, PR - by 60%; 4.6 times increased CTs activity and OSI; 2 times grew peroxide hemolysis (PH) and 1.3 times - EMP. The analysis (depending on the RRT modality) showed that the patients treated by HDF had typical MDAs increase by 3.9 times on a background of CPs by 24%o, TRs - 33%, SH - groups - 25%, TPAe - 51%, G6 - PDHe - 42%; the increase in serum OSI - 5.4 times and 2.6 times in erythrocytes, PR - by 3.6 times and CTs activity by 3,5 times; HD group were characterized by the highest value of MDAe, OSI, PH and CTs, along with more expressed decrease of indices TRs, SH - groups, TPA and G - 6 - FDHe activity compared with rates in patients with HDF. The patients treated with PD had the lowest content of MDAs and the highest values on the background ofTPAe, the significant increase of CPs by 1.7 times and lowest TRs and G - 6 - PDHe. The patients with PD showed twice lower OS activity by OSI.
 Conclusion.Thus, in patients with CKD VD, who had HD, HDF or PD an anemic syndrome was associated with high OS activity and the increased degree of hemolysis. These changes are stipulated by RRT methods: for patients receiving HDF were typical the lowest rates of hemolysis and the highest degree of protection for erythrocytes, and for patients treated with HD - the highest OS.

Regulation of oxidative stress resistance in Campylobacter jejuni, a microaerophilic foodborne pathogen.

Campylobacter jejuni is one of the leading bacterial causes of human gastroenteritis. Due to the increasing rates of human campylobacteriosis, C. jejuni is considered as a serious public health concern worldwide. C. jejuni is a microaerophilic, fastidious bacterium. C. jejuni must overcome a wide range of stress conditions during foodborne transmission to humans, such as food preservation and processing conditions, and even in infection of the gastrointestinal tracts of humans. Particularly, this microaerophilic foodborne pathogen must survive in the atmospheric conditions prior to the initiation of infection. C. jejuni possesses unique regulatory mechanisms for oxidative stress resistance. Lacking OxyR and SoxRS that are highly conserved in other Gram-negative foodborne pathogens, C. jejuni modulates the expression of genes involved in oxidative stress resistance mainly via the peroxide resistance regulator and Campylobacter oxidative stress regulator. Based on recent findings of ours and others, in this review, we described how C. jejuni regulates the expression of oxidative stress defense.

Proteome analysis identifies the Dpr protein of Streptococcus mutans as an important factor in the presence of early streptococcal colonizers of tooth surfaces.

Oral streptococci are primary colonizers of tooth surfaces and Streptococcus mutans is the principal causative agent of dental caries in humans. A number of proteins are involved in the formation of monospecies biofilms by S. mutans. This study analyzed the protein expression profiles of S. mutans biofilms formed in the presence or absence of S. gordonii, a pioneer colonizer of the tooth surface, by two-dimensional gel electrophoresis (2-DE). After identifying S. mutans proteins by Mass spectrometric analysis, their expression in the presence of S. gordonii was analyzed. S. mutans was inoculated with or without S. gordonii DL1. The two species were compartmentalized using 0.2-μl Anopore membranes. The biofilms on polystyrene plates were harvested, and the solubilized proteins were separated by 2-DE. When S. mutans biofilms were formed in the presence of S. gordonii, the peroxide resistance protein Dpr of the former showed 4.3-fold increased expression compared to biofilms that developed in the absence of the pioneer colonizer. In addition, we performed a competition assay using S. mutans antioxidant protein mutants together with S. gordonii and other initial colonizers. Growth of the dpr-knockout S. mutans mutant was significantly inhibited by S. gordonii, as well as by S. sanguinis. Furthermore, a cell viability assay revealed that the viability of the dpr-defective mutant was significantly attenuated compared to the wild-type strain when co-cultured with S. gordonii. Therefore, these results suggest that Dpr might be one of the essential proteins for S. mutans survival on teeth in the presence of early colonizing oral streptococci.

Non-selective regulation of peroxide and superoxide resistance genes by PerR in Campylobacter jejuni.

Campylobacter jejuni is an important foodborne pathogen. The molecular mechanisms for the regulation of oxidative stress resistance have not yet been understood fully in this bacterium. In this study, we investigated how PerR (peroxide stress regulator) modulates the transcriptional regulation of both peroxide and superoxide resistance genes in C. jejuni, particularly under oxidative stress conditions. The transcriptional levels of ahpC, katA, and sodB were substantially increased by aeration and oxidant exposure. Interestingly, a perR mutation completely abrogated the transcriptional response of ahpC, katA and sodB to oxidants. Furthermore, we demonstrated that perR transcription was reduced by aeration and oxidant exposure. In contrast to the unique role of PerR homologs in peroxide stress regulation in other bacteria, C. jejuni PerR directly regulates the transcription of sodB, the most important gene in superoxide defense, as evidenced by the alteration of sodB transcription by the perR mutation and direct binding of rPerR to the sodB promoter. In addition, we also observed notable morphological changes in C. jejuni from spiral rods to cocoid morphology under aerobic conditions. Based on the intracellular ATP levels, C. jejuni entered a viable-but-non-culturable (VBNC) state under aerobic conditions. These findings clearly demonstrate that C. jejuni possesses a unique regulatory mechanism of oxidative stress defense that does not specifically distinguish between peroxide and superoxide defense, and PerR plays a pivotal role in this non-selective regulation of oxidative stress resistance in C. jejuni.

The influence of great nettle polysaccharide on physical activity of animals, processes of phagocytosis and resistance of erythrocyte membranes

Polysaccharide complex is excreted from great nettle, qualitative and quantitative monosaccharide composition is determined, its influence on physical activity, processes of phagocytosis, osmotic, thermic and peroxide resistance of erythrocyte membranes is studied.

Plasmid-encoded tetracycline efflux pump protein alters bacterial stress responses and ecological fitness of Acinetobacter oleivorans.

Acquisition of the extracellular tetracycline (TC) resistance plasmid pAST2 affected host gene expression and phenotype in the oil-degrading soil bacterium, Acinetobacter oleivorans DR1. Whole-transcriptome profiling of DR1 cells harboring pAST2 revealed that all the plasmid genes were highly expressed under TC conditions, and the expression levels of many host chromosomal genes were modulated by the presence of pAST2. The host energy burden imposed by replication of pAST2 led to (i) lowered ATP concentrations, (ii) downregulated expression of many genes involved in cellular growth, and (iii) reduced growth rate. Interestingly, some phenotypes were restored by deleting the plasmid-encoded efflux pump gene tetH, suggesting that the membrane integrity changes resulting from the incorporation of efflux pump proteins also resulted in altered host response under the tested conditions. Alteration of membrane integrity by tetH deletion was shown by measuring permeability of fluorescent probe and membrane hydrophobicity. The presence of the plasmid conferred peroxide and superoxide resistance to cells, but only peroxide resistance was diminished by tetH gene deletion, suggesting that the plasmid-encoded membrane-bound efflux pump protein provided peroxide resistance. The downregulation of fimbriae-related genes presumably led to reduced swimming motility, but this phenotype was recovered by tetH gene deletion. Our data suggest that not only the plasmid replication burden, but also its encoded efflux pump protein altered host chromosomal gene expression and phenotype, which also alters the ecological fitness of the host in the environment.

Structure of the Zymomonas mobilis respiratory chain: oxygen affinity of electron transport and the role of cytochrome c peroxidase.

The genome of the ethanol-producing bacterium Zymomonas mobilis encodes a bd-type terminal oxidase, cytochrome bc1 complex and several c-type cytochromes, yet lacks sequences homologous to any of the known bacterial cytochrome c oxidase genes. Recently, it was suggested that a putative respiratory cytochrome c peroxidase, receiving electrons from the cytochrome bc1 complex via cytochrome c552, might function as a peroxidase and/or an alternative oxidase. The present study was designed to test this hypothesis, by construction of a cytochrome c peroxidase mutant (Zm6-perC), and comparison of its properties with those of a mutant defective in the cytochrome b subunit of the bc1 complex (Zm6-cytB). Disruption of the cytochrome c peroxidase gene (ZZ60192) caused a decrease of the membrane NADH peroxidase activity, impaired the resistance of growing culture to exogenous hydrogen peroxide and hampered aerobic growth. However, this mutation did not affect the activity or oxygen affinity of the respiratory chain, or the kinetics of cytochrome d reduction. Furthermore, the peroxide resistance and membrane NADH peroxidase activity of strain Zm6-cytB had not decreased, but both the oxygen affinity of electron transport and the kinetics of cytochrome d reduction were affected. It is therefore concluded that the cytochrome c peroxidase does not terminate the cytochrome bc1 branch of Z. mobilis, and that it is functioning as a quinol peroxidase.

Oxidative stress based response of a transcriptional regulator, OhrR, from Burkholderia thailandensis (LB252)

Bacteria face a burst of oxidative species during host invasion. As a protective mechanism, they possess several proteins involved in inorganic peroxide sensing. However, much has to be discovered about the sensor‐responder proteins involved in organic hydroperoxide (OHP) resistance, which is important since OHPs are more toxic. Burkholderia thailandensis, a soil dwelling bacterium, contains genes ohrR and ohr, that are involved in OHP detoxification, with the former encoding an organic hydroperoxide reductase regulator (OhrR), a MarR family transcriptional regulator, regulating expression of the gene encoding organic hydroperoxide reductase (Ohr). EMSAs revealed specificity of B. thailandensis OhrR for the promoter region of ohr, with half‐maximal saturation of 3.6 nM. SDS‐PAGE demonstrated formation of reversible, oligomeric species of OhrR on treatment with organic and inorganic oxidants. Conformational changes were indicated by reduced thermal stability of oxidized protein compared to its reduced form (Tm 65.3 °C). Attenuated DNA binding in the presence of oxidants further confirmed structural changes in oxidized OhrR by virtue of disulfide bond formation between redox‐active cysteines. B. thailandensis shares 80% genetic homology with its pathogenic homologues B. pseudomallei and B. mallei, making characterizing its protein machinery involved in peroxide resistance even more crucial.

LRRK2, but not pathogenic mutants, protects against H2O2 stress depending on mitochondrial function and endocytosis in a yeast model

BackgroundMutations in LRRK2 are the most common genetic cause of Parkinson's disease (PD). Studies in the yeast Saccharomyces cerevisiae have provided valuable insights into the mechanisms of cellular dysfunction associated with the expression of faulty PD genes. MethodsWe developed a yeast model for full-length LRRK2 studies. We expressed wild-type (wt) LRRK2 and mutations and evaluated their role during oxidative stress conditions. The involvement of mitochondria was assessed by using rho-zero mutants and by evaluating reactive oxygen species (ROS) production and mitochondrial membrane potential by flow cytometry. The involvement of endocytosis was also studied by testing several endocytic mutants and by following the vacuolar delivery of the probe FM4-64. ResultsExpression of LRRK2 in yeast was associated to increased hydrogen peroxide resistance. This phenotype, which was dependent on mitochondrial function, was not observed for PD-mutants G2019S and R1441C or in the absence of the kinase activity and the WD40 repeat domain. Expression of the pathogenic mutants stimulated ROS production and increased mitochondrial membrane potential. For the PD-mutants, but not for wild-type LRRK2, endocytic defects were also observed. Additionally, several endocytic proteins were required for LRRK2-mediated protection against hydrogen peroxide. ConclusionsOur results indicate that LRRK2 confers cellular protection during oxidative stress depending on mitochondrial function and endocytosis. General significanceBoth the loss of capacity of LRRK2 pathogenic mutants to protect against oxidative stress and their enhancement of dysfunction may be important for the development of PD during the aging process.

The gain of hydrogen peroxide resistance benefits growth fitness in mycobacteria under stress

The gain of hydrogen peroxide resistance benefits growth fitness in mycobacteria under stress

Cytochrome bd Oxidase and Hydrogen Peroxide Resistance in Mycobacterium tuberculosis

Cytochrome bd oxidase is a prokaryotic respiratory oxidase, phylogenetically unrelated to the well-known heme-copper oxidases, which catalyzes the reduction of O2 to 2H2O. Apart from having a role in energy metabolism, this enzyme plays other key functions relevant to physiology and, particularly, to adaptation to stress conditions (reference 1 and references therein). The enzyme is encoded in several pathogens, and its expression was found to correlate positively with virulence in some bacteria. In Mycobacterium tuberculosis, a transient upregulation of cytochrome bd was observed in vivo during the transition from acute to chronic infection of mouse lungs, as was reduced virulence of a mutant strain defective in the cytochrome bd -associated transporter CydC (2). Stimulation …

INFLUENCE OF AMELANCHIER MEDIC POLYSACCHARIDE ON RESISTANCE OF BLOOD CELLS MEMBRANE

When adding to the blood a healthy donor water soluble polysaccharide complex of Amelanchier Medic fruit increases thermal, osmotic and peroxide resistance of erythrocyte membranes protecting cells from destruction caused by the action of experimental unfavorable factors

Single Glutamate to Aspartate Mutation Makes Ferric Uptake Regulator (Fur) as Sensitive to H2O2 as Peroxide Resistance Regulator (PerR)

Let the Fur fly: Mutation of a single glutamate into an aspartate was shown to make the Fe sensor Fur as reactive to H2O2 as the peroxide sensor PerR. In vivo and in vitro peroxide sensitivities of a series of PerR and Fur Asp/Glu mutants were studied by mass spectrometry. A combination of Mössbauer spectroscopy analyses and DFT calculations gave a structural rationale for this behavior.