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Sample records for intracellular redox state

  1. Screening of dietary antioxidants against mitochondria-mediated oxidative stress by visualization of intracellular redox state.

    PubMed

    Maharjan, Sunita; Sakai, Yasuyoshi; Hoseki, Jun

    2016-01-01

    Mitochondrial impairment and the resulting generation of reactive oxygen species (ROS) have been associated with aging and its related pathological conditions. Recently, dietary antioxidants have gained significant attention as potential preventive and therapeutic agents against ROS-generated aging and pathological conditions. We previously demonstrated that food-derived antioxidants prevented intracellular oxidative stress under proteasome inhibition conditions, which was attributed to mitochondrial dysfunction and ROS generation, followed by cell death. Here, we further screened dietary antioxidants for their activity as redox modulators by visualization of the redox state using Redoxfluor, a fluorescent protein redox probe. Direct alleviation of ROS by antioxidants, but not induction of antioxidative enzymes, prevented mitochondria-mediated intracellular oxidation. The effective antioxidants scavenged mitochondrial ROS and suppressed cell death. Our study indicates that redox visualization under mitochondria-mediated oxidative stress is useful for screening potential antioxidants to counteract mitochondrial dysfunction, which has been implicated in aging and the pathogenesis of aging-related diseases.

  2. Bacterial Community Morphogenesis Is Intimately Linked to the Intracellular Redox State

    PubMed Central

    Okegbe, Chinweike; Price-Whelan, Alexa; Sakhtah, Hassan; Hunter, Ryan C.; Newman, Dianne K.

    2013-01-01

    Many microbial species form multicellular structures comprising elaborate wrinkles and concentric rings, yet the rules governing their architecture are poorly understood. The opportunistic pathogen Pseudomonas aeruginosa produces phenazines, small molecules that act as alternate electron acceptors to oxygen and nitrate to oxidize the intracellular redox state and that influence biofilm morphogenesis. Here, we show that the depth occupied by cells within colony biofilms correlates well with electron acceptor availability. Perturbations in the environmental provision, endogenous production, and utilization of electron acceptors affect colony development in a manner consistent with redox control. Intracellular NADH levels peak before the induction of colony wrinkling. These results suggest that redox imbalance is a major factor driving the morphogenesis of P. aeruginosa biofilms and that wrinkling itself is an adaptation that maximizes oxygen accessibility and thereby supports metabolic homeostasis. This type of redox-driven morphological change is reminiscent of developmental processes that occur in metazoans. PMID:23292774

  3. In vivo NAD assay reveals the intracellular NAD contents and redox state in healthy human brain and their age dependences.

    PubMed

    Zhu, Xiao-Hong; Lu, Ming; Lee, Byeong-Yeul; Ugurbil, Kamil; Chen, Wei

    2015-03-03

    NAD is an essential metabolite that exists in NAD(+) or NADH form in all living cells. Despite its critical roles in regulating mitochondrial energy production through the NAD(+)/NADH redox state and modulating cellular signaling processes through the activity of the NAD(+)-dependent enzymes, the method for quantifying intracellular NAD contents and redox state is limited to a few in vitro or ex vivo assays, which are not suitable for studying a living brain or organ. Here, we present a magnetic resonance (MR) -based in vivo NAD assay that uses the high-field MR scanner and is capable of noninvasively assessing NAD(+) and NADH contents and the NAD(+)/NADH redox state in intact human brain. The results of this study provide the first insight, to our knowledge, into the cellular NAD concentrations and redox state in the brains of healthy volunteers. Furthermore, an age-dependent increase of intracellular NADH and age-dependent reductions in NAD(+), total NAD contents, and NAD(+)/NADH redox potential of the healthy human brain were revealed in this study. The overall findings not only provide direct evidence of declined mitochondrial functions and altered NAD homeostasis that accompany the normal aging process but also, elucidate the merits and potentials of this new NAD assay for noninvasively studying the intracellular NAD metabolism and redox state in normal and diseased human brain or other organs in situ.

  4. In vivo NAD assay reveals the intracellular NAD contents and redox state in healthy human brain and their age dependences

    PubMed Central

    Zhu, Xiao-Hong; Lu, Ming; Lee, Byeong-Yeul; Ugurbil, Kamil; Chen, Wei

    2015-01-01

    NAD is an essential metabolite that exists in NAD+ or NADH form in all living cells. Despite its critical roles in regulating mitochondrial energy production through the NAD+/NADH redox state and modulating cellular signaling processes through the activity of the NAD+-dependent enzymes, the method for quantifying intracellular NAD contents and redox state is limited to a few in vitro or ex vivo assays, which are not suitable for studying a living brain or organ. Here, we present a magnetic resonance (MR) -based in vivo NAD assay that uses the high-field MR scanner and is capable of noninvasively assessing NAD+ and NADH contents and the NAD+/NADH redox state in intact human brain. The results of this study provide the first insight, to our knowledge, into the cellular NAD concentrations and redox state in the brains of healthy volunteers. Furthermore, an age-dependent increase of intracellular NADH and age-dependent reductions in NAD+, total NAD contents, and NAD+/NADH redox potential of the healthy human brain were revealed in this study. The overall findings not only provide direct evidence of declined mitochondrial functions and altered NAD homeostasis that accompany the normal aging process but also, elucidate the merits and potentials of this new NAD assay for noninvasively studying the intracellular NAD metabolism and redox state in normal and diseased human brain or other organs in situ. PMID:25730862

  5. Altered intracellular calcium homeostasis and endoplasmic reticulum redox state in Saccharomyces cerevisiae cells lacking Grx6 glutaredoxin.

    PubMed

    Puigpinós, Judit; Casas, Celia; Herrero, Enrique

    2015-01-01

    Glutaredoxin 6 (Grx6) of Saccharomyces cerevisiae is an integral thiol oxidoreductase protein of the endoplasmic reticulum/Golgi vesicles. Its absence alters the redox equilibrium of the reticulum lumen toward a more oxidized state, thus compensating the defects in protein folding/secretion and cell growth caused by low levels of the oxidase Ero1. In addition, null mutants in GRX6 display a more intense unfolded protein response than wild-type cells upon treatment with inducers of this pathway. These observations support a role of Grx6 in regulating the glutathionylation of thiols of endoplasmic reticulum/Golgi target proteins and consequently the equilibrium between reduced and oxidized glutathione in the lumen of these compartments. A specific function influenced by Grx6 activity is the homeostasis of intracellular calcium. Grx6-deficient mutants have reduced levels of calcium in the ER lumen, whereas accumulation occurs at the cytosol from extracellular sources. This results in permanent activation of the calcineurin-dependent pathway in these cells. Some but not all the phenotypes of the mutant are coincident with those of mutants deficient in intracellular calcium transporters, such as the Golgi Pmr1 protein. The results presented in this study provide evidence for redox regulation of calcium homeostasis in yeast cells. © 2015 Puigpinós et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  6. Glycolytic pyruvate regulates P-Glycoprotein expression in multicellular tumor spheroids via modulation of the intracellular redox state.

    PubMed

    Wartenberg, Maria; Richter, Madeleine; Datchev, André; Günther, Sebastian; Milosevic, Nada; Bekhite, Mohamed M; Figulla, Hans-Reiner; Aran, Josep M; Pétriz, Jordi; Sauer, Heinrich

    2010-02-01

    ABC transporters like P-glycoprotein (P-gp/ABCB1) are membrane proteins responsible for the transport of toxic compounds out of non-malignant cells and tumor tissue. To investigate the effect of glycolysis and the tissue redox state on P-gp expression in multicellular tumor spheroids derived from prostate adenocarcinoma cells (DU-145), glioma cells (Gli36), and the human cervix carcinoma cell line KB-3-1 transfected with a P-gp-EGFP fusion gene that allows monitoring of P-gp expression in living cells. During cell culture of DU-145, Gli36, and KB-3-1 tumor spheroids P-gp expression was observed as well as increased lactate and decreased pyruvate levels and expression of glycolytic enzymes. Inhibition of glycolysis for 24 h by either iodoacetate (IA) or 2-deoxy-D-glucose (2-DDG) downregulated P-gp expression which was reversed upon coincubation with the radical scavenger ebselen as shown by semi-quantitative immunohistochemisty in DU-145 and Gli36 tumor spheroids, and by EGFP fluorescence in KB-3-1 tumor spheroids. Consequently endogenous ROS generation in DU-145 tumor spheroids was increased in the presence of either IA or 2-DDG, which was abolished upon coincubation with ebselen. Exogenous addition of pyruvate significantly reduced ROS generation, increased P-gp expression as well as efflux of the P-gp substrate doxorubicin. Doxorubicin transport was significantly blunted by 2-DDG and IA, indicating that inhibition of glycolysis reversed the multidrug resistance phenotype. In summary our data demonstrate that P-gp expression in tumor spheroids is closely related to the glycolytic metabolism of tumor cells and can be downregulated by glycolysis inhibitors via mechanisms that involve changes in the cellular redox state. (c) 2009 Wiley-Liss, Inc.

  7. Post-irradiation hypoxic incubation of X-irradiated MOLT-4 cells reduces apoptotic cell death by changing the intracellular redox state and modulating SAPK/JNK pathways.

    PubMed

    Hamasu, T; Inanami, O; Tsujitani, M; Yokoyama, K; Takahashi, E; Kashiwakura, I; Kuwabara, M

    2005-05-01

    To elucidate radiobiological effects of hypoxia on X-ray-induced apoptosis, MOLT-4 cells were treated under four set of conditions: (1) both X irradiation and incubation under normoxia, (2) X irradiation under hypoxia and subsequent incubation under normoxia, (3) X irradiation under normoxia and subsequent incubation under hypoxia, and (4) both X irradiation and incubation under hypoxia, and the induction of apoptosis was examined by fluorescence microscopy. About 28-33% apoptosis was observed in cells treated under conditions 1 and 2, but this value was significantly reduced to around 18-20% in cells treated under conditions 3 and 4, suggesting that post-irradiation hypoxic incubation rather than hypoxic irradiation mainly caused the reduction of apoptosis. The activation and expression of apoptosis signal-related molecules SAPK/JNK, Fas and caspase-3 were also suppressed by hypoxic incubation. Effects of hypoxic incubation were canceled when cells were treated under conditions 3 and 4 with an oxygen-mimicking hypoxic cell radiosensitizer, whereas the addition of N-acetyl-L-cysteine again reduced the induction of apoptosis. From these results it was concluded that hypoxia reduced the induction of apoptosis by changing the intracellular redox state, followed by the regulation of apoptotic signals in X-irradiated MOLT-4 cells.

  8. Pyridine nucleotide cycling and control of intracellular redox state in relation to poly (ADP-ribose) polymerase activity and nuclear localization of glutathione during exponential growth of Arabidopsis cells in culture.

    PubMed

    Pellny, Till K; Locato, Vittoria; Vivancos, Pedro Diaz; Markovic, Jelena; De Gara, Laura; Pallardó, Federico V; Foyer, Christine H

    2009-05-01

    Pyridine nucleotides, ascorbate and glutathione are major redox metabolites in plant cells, with specific roles in cellular redox homeostasis and the regulation of the cell cycle. However, the regulation of these metabolite pools during exponential growth and their precise functions in the cell cycle remain to be characterized. The present analysis of the abundance of ascorbate, glutathione, and pyridine nucleotides during exponential growth of Arabidopsis cells in culture provides evidence for the differential regulation of each of these redox pools. Ascorbate was most abundant early in the growth cycle, but glutathione was low at this point. The cellular ascorbate to dehydroascorbate and reduced glutathione (GSH) to glutathione disulphide ratios were high and constant but the pyridine nucleotide pools were largely oxidized over the period of exponential growth and only became more reduced once growth had ceased. The glutathione pool increased in parallel with poly (ADP-ribose) polymerase (PARP) activities and with increases in the abundance of PARP1 and PARP2 mRNAs at a time of high cell cycle activity as indicated by transcriptome information. Marked changes in the intracellular partitioning of GSH between the cytoplasm and nucleus were observed. Extension of the exponential growth phase by dilution or changing the media led to increases in the glutathione and nicotinamide adenine dinucleotide, oxidized form (NAD)-plus-nicotinamide adenine dinucleotide, reduced form (NADH) pools and to higher NAD/NADH ratios but the nicotinamide adenine dinucleotide phosphate, oxidized form (NADP)-plus-nicotinamide adenine dinucleotide phosphate, reduced form (NADPH) pool sizes, and NAPD/NADPH ratios were much less affected. The ascorbate, glutathione, and pyridine nucleotide pools and PARP activity decreased before the exponential growth phase ended. We conclude that there are marked changes in intracellular redox state during the growth cycle but that redox homeostasis is

  9. Overexpression of the transcription factor Yap1 modifies intracellular redox conditions and enhances recombinant protein secretion

    PubMed Central

    Delic, Marizela; Graf, Alexandra B.; Koellensperger, Gunda; Haberhauer-Troyer, Christina; Hann, Stephan; Mattanovich, Diethard; Gasser, Brigitte

    2014-01-01

    Oxidative folding of secretory proteins in the endoplasmic reticulum (ER) is a redox active process, which also impacts the redox conditions in the cytosol. As the transcription factor Yap1 is involved in the transcriptional response to oxidative stress, we investigate its role upon the production of secretory proteins, using the yeast Pichia pastoris as model, and report a novel important role of Yap1 during oxidative protein folding. Yap1 is needed for the detoxification of reactive oxygen species (ROS) caused by increased oxidative protein folding. Constitutive co-overexpression of PpYAP1 leads to increased levels of secreted recombinant protein, while a lowered Yap1 function leads to accumulation of ROS and strong flocculation. Transcriptional analysis revealed that more than 150 genes were affected by overexpression of YAP1, in particular genes coding for antioxidant enzymes or involved in oxidation-reduction processes. By monitoring intracellular redox conditions within the cytosol and the ER using redox-sensitive roGFP1 variants, we could show that overexpression of YAP1 restores cellular redox conditions of protein-secreting P. pastoris by reoxidizing the cytosolic redox state to the levels of the wild type. These alterations are also reflected by increased levels of oxidized intracellular glutathione (GSSG) in the YAP1 co-overexpressing strain. Taken together, these data indicate a strong impact of intracellular redox balance on the secretion of (recombinant) proteins without affecting protein folding per se. Re-establishing suitable redox conditions by tuning the antioxidant capacity of the cell reduces metabolic load and cell stress caused by high oxidative protein folding load, thereby increasing the secretion capacity. PMID:28357216

  10. Transient light-induced intracellular oxidation revealed by redox biosensor

    SciTech Connect

    Kolossov, Vladimir L.; Beaudoin, Jessica N.; Hanafin, William P.; DiLiberto, Stephen J.; Kenis, Paul J.A.; Rex Gaskins, H.

    2013-10-04

    Highlights: •Time-resolved live cell imaging revealed light-induced oxidation. •Only the roGFP probe fused with glutaredoxin reveals photooxidation. •The transient oxidation is rapidly reduced by the cytosolic antioxidant system. •Intracellular photooxidation is media-dependent. •Oxidation is triggered exclusively by exposure to short wavelength excitation. -- Abstract: We have implemented a ratiometric, genetically encoded redox-sensitive green fluorescent protein fused to human glutaredoxin (Grx1-roGFP2) to monitor real time intracellular glutathione redox potentials of mammalian cells. This probe enabled detection of media-dependent oxidation of the cytosol triggered by short wavelength excitation. The transient nature of light-induced oxidation was revealed by time-lapse live cell imaging when time intervals of less than 30 s were implemented. In contrast, transient ROS generation was not observed with the parental roGFP2 probe without Grx1, which exhibits slower thiol-disulfide exchange. These data demonstrate that the enhanced sensitivity of the Grx1-roGFP2 fusion protein enables the detection of short-lived ROS in living cells. The superior sensitivity of Grx1-roGFP2, however, also enhances responsiveness to environmental cues introducing a greater likelihood of false positive results during image acquisition.

  11. Monitoring Intracellular Redox Changes in Ozone-exposed airway epithelial cells

    EPA Science Inventory

    Background: The toxicity of many compounds involves oxidative injury to cells. Direct assessment of mechanistic events involved in xenobiotic-induced oxidative stress is not easily achievable. Development of genetically-encoded probes designed for monitoring intracellular redox s...

  12. Monitoring Intracellular Redox Changes in Ozone-exposed airway epithelial cells

    EPA Science Inventory

    Background: The toxicity of many compounds involves oxidative injury to cells. Direct assessment of mechanistic events involved in xenobiotic-induced oxidative stress is not easily achievable. Development of genetically-encoded probes designed for monitoring intracellular redox s...

  13. Fluorescent protein-based FRET sensor for intracellular monitoring of redox status in bacteria at single cell level.

    PubMed

    Abraham, Bobin George; Santala, Ville; Tkachenko, Nikolai V; Karp, Matti

    2014-11-01

    Monitoring of intracellular redox status in a bacterial cell provides vital information about the physiological status of the cell, which can be exploited in several applications such as metabolic engineering and computational modeling. Fluorescent protein-based genetically encoded sensors can be used to monitor intracellular oxidation/reduction status. This study reports the development of a redox sensor for intracellular measurements using fluorescent protein pairs and the phenomenon of Förster resonance energy transfer (FRET). For the development of the sensor, fluorescent proteins Citrine and Cerulean were genetically modified to carry reactive cysteine residues on the protein surface close to the chromophore and a constructed FRET pair was fused using a biotinylation domain as a linker. In oxidized state, the FRET pairs are in close proximity by labile disulfide bond formation resulting in higher FRET efficiency. In reducing environment, the FRET is diminished due to the increased distance between FRET pairs providing large dynamic measurement range to the sensor. Intracellular studies in Escherichia coli mutants revealed the capability of the sensor in detecting real-time redox variations at single cell level. The results were validated by intensity based and time resolved measurements. The functional immobilization of the fluorescent protein-based FRET sensor at solid surfaces for in vitro applications was also demonstrated.

  14. Redox Regulation of Intracellular Zinc: Molecular Signaling in the Life and Death of Neurons

    PubMed Central

    Aizenman, Elias

    2011-01-01

    Abstract Zn2+ has emerged as a major regulator of neuronal physiology, as well as an important signaling agent in neural injury. The intracellular concentration of this metal is tightly regulated through the actions of Zn2+ transporters and the thiol-rich metal binding protein metallothionein, closely linking the redox status of the cell to cellular availability of Zn2+. Accordingly, oxidative and nitrosative stress during ischemic injury leads to an accumulation of neuronal free Zn2+ and the activation of several downstream cell death processes. While this Zn2+ rise is an established signaling event in neuronal cell death, recent evidence suggests that a transient, sublethal accumulation of free Zn2+ can also play a critical role in neuroprotective pathways activated during ischemic preconditioning. Thus, redox-sensitive proteins, like metallothioneins, may play a critical role in determining neuronal cell fate by regulating the localization and concentration of intracellular free Zn2+. Antioxid. Redox Signal. 15, 2249–2263. PMID:20849376

  15. Fully glutathione degradable waterborne polyurethane nanocarriers: Preparation, redox-sensitivity, and triggered intracellular drug release.

    PubMed

    Omrani, Ismail; Babanejad, Niloofar; Shendi, Hasan Kashef; Nabid, Mohammad Reza

    2017-01-01

    Polyurethanes are important class of biomaterials that are extensively used in medical devices. In spite of their easy synthesis, polyurethanes that are fully degradable in response to the intracellular reducing environment are less explored for controlled drug delivery. Herein, a novel glutathione degradable waterborne polyurethane (WPU) nanocarrier for redox triggered intracellular delivery of a model lipophilic anticancer drug, doxorubicin (DOX) is reported. The WPU was prepared from polyaddition reaction of isophorone diisocyanate (IPDI) and a novel linear polyester polyol involving disulfide linkage, disulfide labeled chain extender, dimethylolpropionic acid (DMPA) using dibutyltin dilaurate (DBTDL) as a catalyst. The resulting polyurethane self-assembles into nanocarrier in water. The dynamic light scattering (DLS) measurements and scanning electron microscope (SEM) revealed fast swelling and disruption of nanocarriers under an intracellular reduction-mimicking environment. The in vitro release studies showed that DOX was released in a controlled and redox-dependent manner. MTT assays showed that DOX-loaded WPU had a high in vitro antitumor activity in both HDF noncancer cells and MCF- 7 cancer cells. In addition, it is found that the blank WPU nanocarriers are nontoxic to HDF and MCF-7 cells even at a high concentration of 2mg/mL. Hence, nanocarriers based on disulfide labeled WPU have appeared as a new class of biocompatible and redox-degradable nanovehicle for efficient intracellular drug delivery. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Elevated p66Shc is associated with intracellular redox imbalance in developmentally compromised bovine embryos.

    PubMed

    Bain, Nathan T; Madan, Pavneesh; Betts, Dean H

    2013-01-01

    The in vitro production of mammalian embryos suffers from low efficiency, with 50-70% of all fertilized oocytes failing to develop to the blastocyst stage. This high rate of developmental failure is due, in part, to the effects of oxidative stress generated by reactive oxygen species (ROS). The p66Shc adaptor protein controls oxidative stress response by regulating intracellular ROS levels through multiple pathways, including mitochondrial ROS generation and the repression of antioxidants. This study explored the relationship between p66Shc levels, redox state, and developmental potential in early bovine embryos. Embryo developmental potential was established based on observing their time of first cleavage. P66Shc, catalase, and mitochondrial-specific, manganese-superoxide dismutate (MnSOD) levels were compared between embryos with high and low developmental potentials. Additionally, p66Shc, catalase, and MnSOD content were assayed following a variety of oxidative stress-inducing and-alleviating conditions. Increased developmental potential correlated with significantly lower p66Shc content, significantly higher levels of catalase and MnSOD, and significantly lower intracellular ROS levels (MitoSOX staining) and reduced DNA damage (γ-H2A.X(phospho S139) immunostaining). p66Shc content was increased by either high (20%) O(2) culture or H(2)O(2) treatment, and significantly decreased by supplementing culture media with the antioxidant polyethylene glycol-conjugated catalase. While the abundance of p66Shc varied according to pro/anti-oxidant culture conditions, antioxidant content varied only according to developmental potential. This discrepancy has important implications regarding ongoing efforts towards maximizing in vitro embryo production.

  17. The role of intracellular redox imbalance in nanomaterial induced cellular damage and genotoxicity: a review.

    PubMed

    Kermanizadeh, Ali; Chauché, Caroline; Brown, David M; Loft, Steffen; Møller, Peter

    2015-03-01

    The terms oxidative stress, free radical generation, and intracellular antioxidant protection have become part of everyday nanotoxicology terminology. In recent years, an ever increasing number of in vitro and in vivo studies have implicated disruptions to the redox balance and oxidative stress as one of the main contributors to nanomaterial (NM) induced adverse effects. One of the most important and widely investigated of these effects is genotoxicity. In general, systems that defend an organism against oxidative damage to DNA are very complex and include prevention of reactive oxygen species (ROS) production, neutralizing ROS (scavengers), enzymatic nucleotide pool sanitation, and DNA repair. This review discusses the importance of the maintenance of the redox balance in this context before examining studies that have investigated engineered NM induced redox imbalance and genotoxicity. Furthermore, we identify data gaps, and highlight a number of issues that exist with the methodologies that are routinely utilized to investigate intracellular ROS production or anti-oxidant depletion. We conclude that for a large number of engineered NM types changes in the redox balance toward oxidative stress are normally associated with DNA damage. © 2014 Wiley Periodicals, Inc.

  18. Intracellular Redox Compartmentation and ROS-Related Communication in Regulation and Signaling1[OPEN

    PubMed Central

    2016-01-01

    Recent years have witnessed enormous progress in understanding redox signaling related to reactive oxygen species (ROS) in plants. The consensus view is that such signaling is intrinsic to many developmental processes and responses to the environment. ROS-related redox signaling is tightly wedded to compartmentation. Because membranes function as barriers, highly redox-active powerhouses such as chloroplasts, peroxisomes, and mitochondria may elicit specific signaling responses. However, transporter functions allow membranes also to act as bridges between compartments, and so regulated capacity to transmit redox changes across membranes influences the outcome of triggers produced at different locations. As well as ROS and other oxidizing species, antioxidants are key players that determine the extent of ROS accumulation at different sites and that may themselves act as signal transmitters. Like ROS, antioxidants can be transported across membranes. In addition, the intracellular distribution of antioxidative enzymes may be modulated to regulate or facilitate redox signaling appropriate to the conditions. Finally, there is substantial plasticity in organellar shape, with extensions such as stromules, peroxules, and matrixules playing potentially crucial roles in organelle-organelle communication. We provide an overview of the advances in subcellular compartmentation, identifying the gaps in our knowledge and discussing future developments in the area. PMID:27208308

  19. Proteostasis and REDOX state in the heart

    PubMed Central

    Christians, Elisabeth S.

    2012-01-01

    Force-generating contractile cells of the myocardium must achieve and maintain their primary function as an efficient mechanical pump over the life span of the organism. Because only half of the cardiomyocytes can be replaced during the entire human life span, the maintenance strategy elicited by cardiac cells relies on uninterrupted renewal of their components, including proteins whose specialized functions constitute this complex and sophisticated contractile apparatus. Thus cardiac proteins are continuously synthesized and degraded to ensure proteome homeostasis, also termed “proteostasis.” Once synthesized, proteins undergo additional folding, posttranslational modifications, and trafficking and/or become involved in protein-protein or protein-DNA interactions to exert their functions. This includes key transient interactions of cardiac proteins with molecular chaperones, which assist with quality control at multiple levels to prevent misfolding or to facilitate degradation. Importantly, cardiac proteome maintenance depends on the cellular environment and, in particular, the reduction-oxidation (REDOX) state, which is significantly different among cardiac organelles (e.g., mitochondria and endoplasmic reticulum). Taking into account the high metabolic activity for oxygen consumption and ATP production by mitochondria, it is a challenge for cardiac cells to maintain the REDOX state while preventing either excessive oxidative or reductive stress. A perturbed REDOX environment can affect protein handling and conformation (e.g., disulfide bonds), disrupt key structure-function relationships, and trigger a pathogenic cascade of protein aggregation, decreased cell survival, and increased organ dysfunction. This review covers current knowledge regarding the general domain of REDOX state and protein folding, specifically in cardiomyocytes under normal-healthy conditions and during disease states associated with morbidity and mortality in humans. PMID:22003057

  20. Real-Time Imaging of the Intracellular Glutathione Redox Potential in the Malaria Parasite Plasmodium falciparum

    PubMed Central

    Kasozi, Denis; Mohring, Franziska; Rahlfs, Stefan; Meyer, Andreas J.; Becker, Katja

    2013-01-01

    In the malaria parasite Plasmodium falciparum, the cellular redox potential influences signaling events, antioxidant defense, and mechanisms of drug action and resistance. Until now, the real-time determination of the redox potential in malaria parasites has been limited because conventional approaches disrupt sub-cellular integrity. Using a glutathione biosensor comprising human glutaredoxin-1 linked to a redox-sensitive green fluorescent protein (hGrx1-roGFP2), we systematically characterized basal values and drug-induced changes in the cytosolic glutathione-dependent redox potential (EGSH) of drug-sensitive (3D7) and resistant (Dd2) P. falciparum parasites. Via confocal microscopy, we demonstrated that hGrx1-roGFP2 rapidly detects EGSH changes induced by oxidative and nitrosative stress. The cytosolic basal EGSH of 3D7 and Dd2 were estimated to be −314.2±3.1 mV and −313.9±3.4 mV, respectively, which is indicative of a highly reducing compartment. We furthermore monitored short-, medium-, and long-term changes in EGSH after incubation with various redox-active compounds and antimalarial drugs. Interestingly, the redox cyclers methylene blue and pyocyanin rapidly changed the fluorescence ratio of hGrx1-roGFP2 in the cytosol of P. falciparum, which can, however, partially be explained by a direct interaction with the probe. In contrast, quinoline and artemisinin-based antimalarial drugs showed strong effects on the parasites' EGSH after longer incubation times (24 h). As tested for various conditions, these effects were accompanied by a drop in total glutathione concentrations determined in parallel with alternative methods. Notably, the effects were generally more pronounced in the chloroquine-sensitive 3D7 strain than in the resistant Dd2 strain. Based on these results hGrx1-roGFP2 can be recommended as a reliable and specific biosensor for real-time spatiotemporal monitoring of the intracellular EGSH in P. falciparum. Applying this technique in further

  1. Opening of connexin 43 hemichannels is increased by lowering intracellular redox potential

    PubMed Central

    Retamal, Mauricio A.; Schalper, Kurt A.; Shoji, Kenji F.; Bennett, Michael V. L.; Sáez, Juan C.

    2007-01-01

    Nonjunctional membrane in many cells contains connexin gap junction hemichannels (or connexons) that can open to allow permeation of small molecules. Opening of Cx43 hemichannels is infrequent in normal extracellular Ca2+ and enhanced by low Ca2+, positive membrane potentials, and dephosphorylation of critical residues. Here we report that lowering intracellular redox potential increases Cx43 hemichannel open probability under otherwise normal conditions. We studied dye uptake and single-channel activity in HeLa cells transfected with wild-type Cx43, Cx43 with enhanced GFP attached to its C terminus (Cx43-EGFP), and Cx43 with enhanced GFP attached to its N terminus (EGFP-Cx43). Dithiothreitol [(DTT) 10 mM], a membrane permeant-reducing agent, increased the rate of dye uptake by cells expressing Cx43 and Cx43-EGFP, but not by parental cells or cells expressing EGFP-Cx43. Induced dye uptake was blocked by La3+, by a peptide gap junction and hemichannel blocker (gap 26), and by flufenamic acid. DTT increased Cx43-EGFP hemichannel opening at positive voltages. Bath application of reduced glutathione, a membrane impermeant-reducing agent, did not increase dye uptake, but glutathione in the recording pipette increased hemichannel opening at positive voltages, suggesting that it acted intracellularly. DTT caused little change in levels of surface Cx43 or Cx43-EGFP, or in intracellular pH. These findings suggest that lowering intracellular redox potential increases the opening of Cx43 and Cx43-EGFP hemichannels, possibly by action on cytoplasmic cysteine residues in the connexin C terminus. PMID:17494739

  2. Opening of connexin 43 hemichannels is increased by lowering intracellular redox potential.

    PubMed

    Retamal, Mauricio A; Schalper, Kurt A; Shoji, Kenji F; Bennett, Michael V L; Sáez, Juan C

    2007-05-15

    Nonjunctional membrane in many cells contains connexin gap junction hemichannels (or connexons) that can open to allow permeation of small molecules. Opening of Cx43 hemichannels is infrequent in normal extracellular Ca(2+) and enhanced by low Ca(2+), positive membrane potentials, and dephosphorylation of critical residues. Here we report that lowering intracellular redox potential increases Cx43 hemichannel open probability under otherwise normal conditions. We studied dye uptake and single-channel activity in HeLa cells transfected with wild-type Cx43, Cx43 with enhanced GFP attached to its C terminus (Cx43-EGFP), and Cx43 with enhanced GFP attached to its N terminus (EGFP-Cx43). Dithiothreitol [(DTT) 10 mM], a membrane permeant-reducing agent, increased the rate of dye uptake by cells expressing Cx43 and Cx43-EGFP, but not by parental cells or cells expressing EGFP-Cx43. Induced dye uptake was blocked by La(3+), by a peptide gap junction and hemichannel blocker (gap 26), and by flufenamic acid. DTT increased Cx43-EGFP hemichannel opening at positive voltages. Bath application of reduced glutathione, a membrane impermeant-reducing agent, did not increase dye uptake, but glutathione in the recording pipette increased hemichannel opening at positive voltages, suggesting that it acted intracellularly. DTT caused little change in levels of surface Cx43 or Cx43-EGFP, or in intracellular pH. These findings suggest that lowering intracellular redox potential increases the opening of Cx43 and Cx43-EGFP hemichannels, possibly by action on cytoplasmic cysteine residues in the connexin C terminus.

  3. Overlap of Doxycycline Fluorescence with that of the Redox-Sensitive Intracellular Reporter roGFP.

    PubMed

    Khader, Heba; Solodushko, Victor; Al-Mehdi, Abu Bakr; Audia, Jonathon; Fouty, Brian

    2014-03-01

    Tetracycline-inducible systems allow for either suppression or induction of transgene expression to facilitate studies of cell physiology. Doxycycline is a preferred inducer for these gene expression systems due to its membrane permeability; however, the heterocyclic structure of doxycycline exhibits fluorogenic properties that can potentially bias measurement of other fluorochromes. Thus the simultaneous use of tetracycline-inducible systems and fluorescent proteins as reporter genes or as intracellular biosensors may lead to potentially confounding results. Herein, using cells which co-express the ratiometric redox sensitive intracellular reporter, roGFP, and a tetracycline-inducible reporter plasmid encoding the reporter gene, mCherry, as a model system, we describe the overlapping intracellular fluorescent signals between doxycycline and commonly used intracellular fluorescent probes. In our cells, the addition of doxycycline to cells caused a dose- and time-dependent increase in cell fluorescence with 405 nm excitation which overlapped with that of the oxidized configuration of roGFP. Incubating cells in concentrations of doxycycline less than 1 μg/mL and removing doxycycline from the media 60 min before performing experiments eliminated fluorescence interference while still maintaining maximal reporter transgene activation.

  4. Intracellular redox induced drug release in cancerous and mesenchymal stem cells.

    PubMed

    Timin, Alexander S; Lepik, Kirill V; Muslimov, Albert R; Gorin, Dmitry A; Afanasyev, Boris V; Sukhorukov, Gleb B

    2016-11-01

    In this report, we investigated intracellular redox induced drug release in cancerous cells and human mesenchymal stem cells (MSCs) as an example of healthy cells using redox-responsive microcapsules with covalently bonded anti-cancer drug (doxorubicin) via the amine-reactive cross-linker, 3,3'-dithiobis(sulfosuccinimidyl propionate) containing disulfide bond. Such rationally designed capsules with incorporated redox-sensitive cross-linker are capable of controllable Dox release in the presence of glutathione (GSH) due to a thiol-cleavable disulfide bonds. The treatment of human MSCs and human cervical cancer cell line (HeLa) with Dox-conjugated capsules showed that the Dox release was observed only when capsules incubated with HeLa cells which can be induced by high GSH level in cancerous (HeLa) cells. Moreover, the results of cell viability indicated that Dox-conjugated capsules are more effective when inducing cell death of HeLa than free Dox improving the anti-tumor efficacy of chemotherapeutic drug and simultaneously they possess lower cytotoxicity against MSCs compared to cancerous cells. Such properties are important in design of smart drug carriers for efficient cancer therapy. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Electrochemical detection of intracellular and cell membrane redox systems in Saccharomyces cerevisiae

    NASA Astrophysics Data System (ADS)

    Rawson, Frankie J.; Downard, Alison J.; Baronian, Keith H.

    2014-06-01

    Redox mediators can interact with eukaryote cells at a number of different cell locations. While cell membrane redox centres are easily accessible, the redox centres of catabolism are situated within the cytoplasm and mitochondria and can be difficult to access. We have systematically investigated the interaction of thirteen commonly used lipophilic and hydrophilic mediators with the yeast Saccharomyces cerevisiae. A double mediator system is used in which ferricyanide is the final electron acceptor (the reporter mediator). After incubation of cells with mediators, steady state voltammetry of the ferri/ferrocyanide redox couple allows quantitation of the amount of mediator reduced by the cells. The plateau current at 425 mV vs Ag/AgCl gives the analytical signal. The results show that five of the mediators interact with at least three different trans Plasma Membrane Electron Transport systems (tPMETs), and that four mediators cross the plasma membrane to interact with cytoplasmic and mitochondrial redox molecules. Four of the mediators inhibit electron transfer from S. cerevisiae. Catabolic inhibitors were used to locate the cellular source of electrons for three of the mediators.

  6. Electrochemical detection of intracellular and cell membrane redox systems in Saccharomyces cerevisiae

    PubMed Central

    Rawson, Frankie J.; Downard, Alison J.; Baronian, Keith H.

    2014-01-01

    Redox mediators can interact with eukaryote cells at a number of different cell locations. While cell membrane redox centres are easily accessible, the redox centres of catabolism are situated within the cytoplasm and mitochondria and can be difficult to access. We have systematically investigated the interaction of thirteen commonly used lipophilic and hydrophilic mediators with the yeast Saccharomyces cerevisiae. A double mediator system is used in which ferricyanide is the final electron acceptor (the reporter mediator). After incubation of cells with mediators, steady state voltammetry of the ferri/ferrocyanide redox couple allows quantitation of the amount of mediator reduced by the cells. The plateau current at 425 mV vs Ag/AgCl gives the analytical signal. The results show that five of the mediators interact with at least three different trans Plasma Membrane Electron Transport systems (tPMETs), and that four mediators cross the plasma membrane to interact with cytoplasmic and mitochondrial redox molecules. Four of the mediators inhibit electron transfer from S. cerevisiae. Catabolic inhibitors were used to locate the cellular source of electrons for three of the mediators. PMID:24910017

  7. The Role of Copper Chaperone Atox1 in Coupling Redox Homeostasis to Intracellular Copper Distribution

    PubMed Central

    Hatori, Yuta; Lutsenko, Svetlana

    2016-01-01

    Human antioxidant protein 1 (Atox1) is a small cytosolic protein with an essential role in copper homeostasis. Atox1 functions as a copper carrier facilitating copper transfer to the secretory pathway. This process is required for activation of copper dependent enzymes involved in neurotransmitter biosynthesis, iron efflux, neovascularization, wound healing, and regulation of blood pressure. Recently, new cellular roles for Atox1 have emerged. Changing levels of Atox1 were shown to modulate response to cancer therapies, contribute to inflammatory response, and protect cells against various oxidative stresses. It has also become apparent that the activity of Atox1 is tightly linked to the cellular redox status. In this review, we summarize biochemical information related to a dual role of Atox1 as a copper chaperone and an antioxidant. We discuss how these two activities could be linked and contribute to establishing the intracellular copper balance and functional identity of cells during differentiation. PMID:27472369

  8. Anti-cancer effects of cerium oxide nanoparticles and its intracellular redox activity.

    PubMed

    Pešić, Milica; Podolski-Renić, Ana; Stojković, Sonja; Matović, Branko; Zmejkoski, Danica; Kojić, Vesna; Bogdanović, Gordana; Pavićević, Aleksandra; Mojović, Miloš; Savić, Aleksandar; Milenković, Ivana; Kalauzi, Aleksandar; Radotić, Ksenija

    2015-05-05

    Data on medical applications of cerium oxide nanoparticles CeO2 (CONP) are promising, yet information regarding their action in cells is incomplete and there are conflicting reports about in vitro toxicity. Herein, we have studied cytotoxic effect of CONP in several cancer and normal cell lines and their potential to change intracellular redox status. The IC50 was achieved only in two of eight tested cell lines, melanoma 518A2 and colorectal adenocarcinoma HT-29. Self-propagating room temperature method was applied to produce CONP with an average crystalline size of 4 nm. The results confirmed presence of Ce(3+) and O(2-) vacancies. The induction of cell death by CONP and the production of reactive oxygen species (ROS) were analyzed by flow-cytometry. Free radicals related antioxidant capacity of the cells was studied by the reduction of stable free radical TEMPONE using electron spin resonance spectroscopy. CONP showed low or moderate cytotoxicity in cancer cell lines: adenocarcinoma DLD1 and multi-drug resistant DLD1-TxR, non-small cell lung carcinoma NCI-H460 and multi-drug resistant NCI-H460/R, while normal cell lines (keratinocytes HaCaT, lung fetal fibroblasts MRC-5) were insensitive. The most sensitive were 518A2 melanoma and HT-29 colorectal adenocarcinoma cell lines, with the IC50 values being between 100 and 200 μM. Decreased rate of TEMPONE reduction and increased production of certain ROS species (peroxynitrite and hydrogen peroxide anion) indicates that free radical metabolism, thus redox status was changed, and antioxidant capacity damaged in the CONP treated 518A2 and HT-29 cells. In conclusion, changes in intracellular redox status induced by CONP are partly attributed to the prooxidant activity of the nanoparticles. Further, ROS induced cell damages might eventually lead to the cell death. However, low inhibitory potential of CONP in the other human cell lines tested indicates that CONP may be safe for human usage in industry and medicine.

  9. Thiol/disulfide redox states in signaling and sensing

    PubMed Central

    Go, Young-Mi; Jones, Dean P.

    2015-01-01

    Rapid advances in redox systems biology are creating new opportunities to understand complexities of human disease and contributions of environmental exposures. New understanding of thiol-disulfide systems have occurred during the past decade as a consequence of the discoveries that thiol and disulfide systems are maintained in kinetically controlled steady-states displaced from thermodynamic equilibrium, that a widely distributed family of NADPH oxidases produces oxidants that function in cell signaling, and that a family of peroxiredoxins utilize thioredoxin as a reductant to complement the well-studied glutathione antioxidant system for peroxide elimination and redox regulation. This review focuses on thiol/disulfide redox state in biologic systems and the knowledge base available to support development of integrated redox systems biology models to better understand the function and dysfunction of thiol-disulfide redox systems. In particular, central principles have emerged concerning redox compartmentalization and utility of thiol/disulfide redox measures as indicators of physiologic function. Advances in redox proteomics show that, in addition to functioning in protein active sites and cell signaling, cysteine residues also serve as redox sensors to integrate biologic functions. These advances provide a framework for translation of redox systems biology concepts to practical use in understanding and treating human disease. Biological responses to cadmium, a widespread environmental agent, are used to illustrate the utility of these advances to the understanding of complex pleiotropic toxicities. PMID:23356510

  10. Proline modulates the intracellular redox environment and protects mammalian cells against oxidative stress.

    PubMed

    Krishnan, Navasona; Dickman, Martin B; Becker, Donald F

    2008-02-15

    The potential of proline to suppress reactive oxygen species (ROS) and apoptosis in mammalian cells was tested by manipulating intracellular proline levels exogenously and endogenously by overexpression of proline metabolic enzymes. Proline was observed to protect cells against H(2)O(2), tert-butyl hydroperoxide, and a carcinogenic oxidative stress inducer but was not effective against superoxide generators such as menadione. Oxidative stress protection by proline requires the secondary amine of the pyrrolidine ring and involves preservation of the glutathione redox environment. Overexpression of proline dehydrogenase (PRODH), a mitochondrial flavoenzyme that oxidizes proline, resulted in 6-fold lower intracellular proline content and decreased cell survival relative to control cells. Cells overexpressing PRODH were rescued by pipecolate, an analog that mimics the antioxidant properties of proline, and by tetrahydro-2-furoic acid, a specific inhibitor of PRODH. In contrast, overexpression of the proline biosynthetic enzymes Delta(1)-pyrroline-5-carboxylate (P5C) synthetase (P5CS) and P5C reductase (P5CR) resulted in 2-fold higher proline content, significantly lower ROS levels, and increased cell survival relative to control cells. In different mammalian cell lines exposed to physiological H(2)O(2) levels, increased endogenous P5CS and P5CR expression was observed, indicating that upregulation of proline biosynthesis is an oxidative stress response.

  11. Fluoroquinolones Lower Constitutive H2AX and ATM Phosphorylation in TK6 Lymphoblastoid Cells via Modulation of Intracellular Redox Status

    PubMed Central

    Halicka, H. Dorota; Smart, Daniel J.; Traganos, Frank; Williams, Gary M.; Darzynkiewicz, Zbigniew

    2008-01-01

    Accumulation of reactive oxygen species (ROS)-induced damage and mutations in genomic DNA is considered the primary etiology of aging and age-related pathologies including cancer. Strategies aimed at slowing these conditions often involve protecting against oxidative DNA damage via modulation of the intracellular redox state. Recently, a biomarker of DNA double-strand breaks (DSBs), serine-139-phosphorylated histone H2AX (γH2AX), and its upstream mediator, activated PI-3-related kinase ATM (ATMP1981), were shown to be constitutively expressed in cells and modulated by antioxidant treatment. Thus, both constitutive histone H2AX phosphorylation (CHP) and constitutive ATM activation (CAA) are thought to reflect a cell’s response to endogenous ROS-induced DSBs. In the present study, we investigated the effects of a battery of fluoroquinolone (FQ) compounds, namely Ciprofloxacin, Enrofloxacin, Gatifloxacin, Lomefloxacin and Ofloxacin, on CHP and CAA in human TK6 lymphoblastoid cells. All FQs tested reduced CHP and CAA compared to controls following 6 and 24 h treatment, with CAA being more sensitive to their effects at both time points. In addition, intracellular ROS levels and mitochondrial activities were also lowered in FQ-treated cells at 6 and 24 h. We believe that FQs mediate this effect via a combination of ROS-scavenging and mitochondrial suppression, and therefore may protect against the onset or slow the progression of numerous oxidative pathophysiological conditions. PMID:19815954

  12. Involvement of Redox State in the Aging of Drosophila melanogaster

    PubMed Central

    Radyuk, Svetlana N.; Sohal, Rajindar S.

    2013-01-01

    Abstract Significance: The main objective of this review was to provide an exposition of investigations, conducted in Drosophila melanogaster, on the role of reactive oxygen species and redox state in the aging process. While early transgenic studies did not clearly support the validity of the oxidative stress hypothesis of aging, predicated on the accumulation of structural damage, they spawned a broader search for redox-related effects that might impact the aging process. Recent Advances: Initial evidence implicating the thiol redox state as a possible causative factor in aging has been obtained in Drosophila. Overexpression of genes, such as GCL, G6PD, Prx2, and Prx5, which are involved in the maintenance of thiol redox homeostasis, has strong positive effects on longevity. Further, the depletion of peroxiredoxin activity in the mitochondria through the double knockdown of Prx5 and Prx3 not only results in a redox crisis but also elicits a rapid aging phenotype. Critical Issues: Herein, we summarize the present status of knowledge about the main components of the machinery controlling thiol redox homeostasis and describe how age-related redox fluctuations might impact aging more acutely through disruption of the redox-sensitive signaling mechanisms rather than via the simple accumulation of structural damage. Future Directions: Based on these initial insights into the plausible impact of redox fluctuations on redox signaling, future studies should focus on the pathways that have been explicitly implicated in aging, such as insulin signaling, TOR, and JNK/FOXO, with particular attention to elements that are redox sensitive. Antioxid. Redox Signal. 19, 788–803. PMID:23458359

  13. Redox State of the Neoarchean Earth Environment

    NASA Technical Reports Server (NTRS)

    Zerkle, Aubrey L.; Claire, Mark W.; Domagal-Goldman, Shawn; Farquhar, James; Poulton, Simon W.

    2011-01-01

    A Titan-like organic haze has been hypothesized for Earth's atmosphere prior to widespread surface oxygenation approx.2.45 billion years ago (Ga). We present a high-resolution record of quadruple sulfur isotopes, carbon isotopes, and Fe speciation from the approx.2.65-2.5 Ga Ghaap Group, South Africa, which suggest a linkage between organic haze and the biogeochemical cycling of carbon, sulfur, oxygen, and iron on the Archean Earth. These sediments provide evidence for oxygen production in microbial mats and localized oxygenation of surface waters. However, this oxygen production occurred under a reduced atmosphere which existed in multiple distinct redox states that correlate to changes in carbon and sulfur isotopes. The data are corroborated by photochemical model results that suggest bi-stable transitions between organic haze and haze-free atmospheric conditions in the Archean. These geochemical correlations also extend to other datasets, indicating that variations in the character of anomalous sulfur fractionation could provide insight into the role of carbon-bearing species in the reducing Archean atmosphere.

  14. Intracellular redox-activated anticancer drug delivery by functionalized hollow mesoporous silica nanoreservoirs with tumor specificity.

    PubMed

    Luo, Zhong; Hu, Yan; Cai, Kaiyong; Ding, Xingwei; Zhang, Quan; Li, Menghuan; Ma, Xing; Zhang, Beilu; Zeng, Yongfei; Li, Peizhou; Li, Jinghua; Liu, Junjie; Zhao, Yanli

    2014-09-01

    In this study, a type of intracellular redox-triggered hollow mesoporous silica nanoreservoirs (HMSNs) with tumor specificity was developed in order to deliver anticancer drug (i.e., doxorubicin (DOX)) to the target tumor cells with high therapeutic efficiency and reduced side effects. Firstly, adamantanamine was grafted onto the orifices of HMSNs using a redox-cleavable disulfide bond as an intermediate linker. Subsequently, a synthetic functional molecule, lactobionic acid-grafted-β-cyclodextrin (β-CD-LA), was immobilized on the surface of HMSNs through specific complexation with the adamantyl group, where β-CD served as an end-capper to keep the loaded drug within HMSNs. β-CD-LA on HMSNs could also act as a targeting agent towards tumor cells (i.e., HepG2 cells), since the lactose group in β-CD-LA is a specific ligand binding with the asialoglycoprotein receptor (ASGP-R) on HepG2 cells. In vitro studies demonstrated that DOX-loaded nanoreservoirs could be selectively endocytosed by HepG2 cells, releasing therapeutic DOX into cytoplasm and efficiently inducing the apoptosis and cell death. In vivo investigations further confirmed that DOX-loaded nanoreservoirs could permeate into the tumor sites and actively interact with tumor cells, which inhibited the tumor growth with the minimized side effect. On the whole, this drug delivery system exhibits a great potential as an efficient carrier for targeted tumor therapy in vitro and in vivo. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Redox-sensitive materials for drug delivery: targeting the correct intracellular environment, tuning release rates, and appropriate predictive systems.

    PubMed

    Phillips, Daniel J; Gibson, Matthew I

    2014-08-10

    The development of responsive drug delivery systems (DDS) holds great promise as a tool for improving the pharmacokinetic properties of drug compounds. Redox-sensitive systems are particularly attractive given the rich variety of redox gradients present in vivo. These gradients, where the circulation is generally considered oxidizing and the cellular environment is substantially more reducing, provide attractive options for targeted, specific cargo delivery. Experimental evidence suggests that a "one size fits all" redox gradient does not exist. Rather, there are subtle differences in redox potential within a cell, while the chemical nature of reducing agents in these microenvironments varies. Recent works have demonstrated an ability to modulate the degradation rate of redox-susceptible groups and, hence, provide new tools to engineer precision-targeted DDS. Modern synthetic and macromolecular chemistry provides access to a wide range of redox-susceptible architectures. However, in order to utilize these in real applications, the actual chemical nature of the redox-susceptible group, the sub-cellular location being targeted, and the redox microenvironment being encountered should be considered in detail. This is critical to avoid the over-simplification possible when using non-biological reducing agents, which may provide inaccurate kinetic information, and to ensure these materials can be advanced beyond simple "on/off" systems. Furthermore, a strong case can be made for the use of biorelevant reducing agents such as glutathione when demonstrating a materials redox response. A further understanding of the complexities of the extra- and intracellular microenvironments would greatly assist with the design and application of DDS.

  16. Redox-responsive micelles self-assembled from dynamic covalent block copolymers for intracellular drug delivery.

    PubMed

    Yang, Qinglai; Tan, Lianjiang; He, Changyu; Liu, Bingya; Xu, Yuhong; Zhu, Zhenggang; Shao, Zhifeng; Gong, Bing; Shen, Yu-Mei

    2015-04-01

    Redox-responsive micelles self-assembled from dynamic covalent block copolymers with double disulfide linkage in the backbone have been developed successfully. The amphiphilic block copolymers PEG-PLA associated with complementary H-bonding sequences can self-assemble into spherical micelles in aqueous media with sizes from 34 nm to 107 nm with different molar mass of PEG and PLA. Moreover, in vitro drug release analyses indicate that reductive environment can result in triggered drug release profiles. The glutathione (GSH) mediated intracellular drug delivery was investigated against HeLa human cervical carcinoma cell line. Flow cytometry and fluorescence microscopy measurements demonstrated that the micelles exhibited faster drug release in glutathione monoester (GSH-OEt) pretreated HeLa cells than that in the nonpretreated cells. Cytotoxicity assay of DOX-loaded micelles indicated the higher cellular proliferation inhibition against 10 mM of GSH-OEt pretreated HeLa cells than that of the nonpretreated ones. These reduction-responsive, biodegradable and biocompatibility micelles could provide a favorable platform to construct excellent drug delivery systems for cancer therapy.

  17. Different redox states of metallothionein/thionein in biological tissue

    PubMed Central

    Krężel, Artur; Maret, Wolfgang

    2006-01-01

    Mammalian metallothioneins are redox-active metalloproteins. In the case of zinc metallothioneins, the redox activity resides in the cysteine sulfur ligands of zinc. Oxidation releases zinc, whereas reduction re-generates zinc-binding capacity. Attempts to demonstrate the presence of the apoprotein (thionein) and the oxidized protein (thionin) in tissues posed tremendous analytical challenges. One emerging strategy is differential chemical modification of cysteine residues in the protein. Chemical modification distinguishes three states of the cysteine ligands (reduced, oxidized and metal-bound) based on (i) quenched reactivity of the thiolates when bound to metal ions and restoration of thiol reactivity in the presence of metal-ion-chelating agents, and (ii) modification of free thiols with alkylating agents and subsequent reduction of disulfides to yield reactive thiols. Under normal physiological conditions, metallothionein exists in three states in rat liver and in cell lines. Ras-mediated oncogenic transformation of normal HOSE (human ovarian surface epithelial) cells induces oxidative stress and increases the amount of thionin and the availability of cellular zinc. These experiments support the notion that metallothionein is a dynamic protein in terms of its redox state and metal content and functions at a juncture of redox and zinc metabolism. Thus redox control of zinc availability from this protein establishes multiple methods of zinc-dependent cellular regulation, while the presence of both oxidized and reduced states of the apoprotein suggest that they serve as a redox couple, the generation of which is controlled by metal ion release from metallothionein. PMID:17134375

  18. Redox state is a central modulator of the balance between self-renewal and differentiation in a dividing glial precursor cell

    PubMed Central

    Smith, Joel; Ladi, Ena; Mayer-Pröschel, Margot; Noble, Mark

    2000-01-01

    We have discovered that intracellular redox state appears to be a necessary and sufficient modulator of the balance between self-renewal and differentiation in dividing oligodendrocyte-type-2 astrocyte progenitor cells. The intracellular redox state of freshly isolated progenitors allows prospective isolation of cells with different self-renewal characteristics. Redox state is itself modulated by cell-extrinsic signaling molecules that alter the balance between self-renewal and differentiation: growth factors that promote self-renewal cause progenitors to become more reduced, while signaling molecules that promote differentiation cause progenitors to become more oxidized. Moreover, pharmacological antagonists of the redox effects of these cell-extrinsic signaling molecules antagonize their effects on self-renewal and differentiation, indicating that cell-extrinsic signaling molecules that modulate this balance converge on redox modulation as a critical component of their effector mechanism. PMID:10944195

  19. Statins: Pleiotropic Regulators of Cardiovascular Redox State

    PubMed Central

    Channon, Keith M.

    2014-01-01

    Abstract Lipid-lowering treatment with statins is one of the most effective therapeutic strategies in cardiovascular medicine because they reduce cardiovascular risk in both primary and secondary prevention. Despite the well-established links between low-density lipoprotein and cardiovascular risk, the clinical benefit from statin treatment is not fully explained by their lipid-lowering potential. A number of pleiotropic effects of statins have been described over the past decade, and their ability to suppress global oxidative stress is probably one of the most important mechanisms by which they exert their beneficial effects on the cardiovascular system. In this Forum, there are review articles discussing the molecular mechanisms by which statins modify redox signaling in the vasculature and the heart. They exert direct effects on the vascular wall and the myocardium or indirect by targeting the interactions between the cardiovascular system and adipose tissue or circulating cell types. The review articles in this Forum follow a translational approach and link the molecular mechanisms by which statins modify cardiovascular redox signaling with their clinical benefit in the prevention and treatment of cardiovascular diseases. Antioxid. Redox Signal. 20, 1195–1197. PMID:24409984

  20. Statins: pleiotropic regulators of cardiovascular redox state.

    PubMed

    Antoniades, Charalambos; Channon, Keith M

    2014-03-10

    Lipid-lowering treatment with statins is one of the most effective therapeutic strategies in cardiovascular medicine because they reduce cardiovascular risk in both primary and secondary prevention. Despite the well-established links between low-density lipoprotein and cardiovascular risk, the clinical benefit from statin treatment is not fully explained by their lipid-lowering potential. A number of pleiotropic effects of statins have been described over the past decade, and their ability to suppress global oxidative stress is probably one of the most important mechanisms by which they exert their beneficial effects on the cardiovascular system. In this Forum, there are review articles discussing the molecular mechanisms by which statins modify redox signaling in the vasculature and the heart. They exert direct effects on the vascular wall and the myocardium or indirect by targeting the interactions between the cardiovascular system and adipose tissue or circulating cell types. The review articles in this Forum follow a translational approach and link the molecular mechanisms by which statins modify cardiovascular redox signaling with their clinical benefit in the prevention and treatment of cardiovascular diseases.

  1. Bioelectrochemical probing of intracellular redox processes in living yeast cells--application of redox polymer wiring in a microfluidic environment.

    PubMed

    Heiskanen, Arto; Coman, Vasile; Kostesha, Natalie; Sabourin, David; Haslett, Nick; Baronian, Keith; Gorton, Lo; Dufva, Martin; Emnéus, Jenny

    2013-04-01

    Conventionally, microbial bioelectrochemical assays have been conducted using immobilized cells on an electrode that is placed in an electrochemical batch cell. In this paper, we describe a developed microfluidic platform with integrated microelectrode arrays for automated bioelectrochemical assays utilizing a new double mediator system to map redox metabolism and screen for genetic modifications in Saccharomyces cerevisiae cells. The function of this new double mediator system based on menadione and osmium redox polymer (PVI-Os) is demonstrated. "Wiring" of S. cerevisiae cells using PVI-Os shows a significant improvement of bioelectrochemical monitoring in a microfluidic environment and functions as an effective immobilization matrix for cells that are not strongly adherent. The function of the developed microfluidic platform is demonstrated using two strains of S. cerevisiae, ENY.WA and its deletion mutant EBY44, which lacks the enzyme phosphoglucose isomerase. The cellular responses to introduced glucose and fructose were recorded for the two S. cerevisiae strains, and the obtained results are compared with previously published work when using an electrochemical batch cell, indicating that microfluidic bioelectrochemical assays employing the menadione-PVI-Os double mediator system provides an effective means to conduct automated microbial assays.

  2. Changes in the redox state in the retina and brain during the onset of diabetes in rats.

    PubMed

    Salceda, R; Vilchis, C; Coffe, V; Hernández-Muñoz, R

    1998-06-01

    Diabetic retinopathy is thought to result from chronic changes in the metabolic pathways of the retina. Hyperglycemia leads to increased intracellular glucose concentrations, alterations in glucose degradation and an increase in lactate/pyruvate ratio. We measured lactate content in retina and other ocular and non-ocular tissues from normal and diabetic rats in the early stages of streptozotocin-induced diabetes. The intracellular redox state was calculated from the cytoplasmic [lactate]/[pyruvate] ratio. Elevated lactate concentration were found in retina and cerebral cortex from diabetic rats. These concentrations led to a significant and progressive decrease in the NAD+/NADH ratio, suggesting that altered glucose metabolism is an initial step of retinopathy. It is thus possible that tissues such as cerebral cortex have mechanisms that prevent the damaging effect of lactate produced by hyperglycemia and/or alterations of the intracellular redox state.

  3. Zn2+-dependent redox switch in the intracellular T1-T1 interface of a Kv channel.

    PubMed

    Wang, Guangyu; Strang, Candace; Pfaffinger, Paul J; Covarrubias, Manuel

    2007-05-04

    The thiol-based redox regulation of proteins plays a central role in cellular signaling. Here, we investigated the redox regulation at the Zn(2+) binding site (HX(5)CX(20)CC) in the intracellular T1-T1 inter-subunit interface of a Kv4 channel. This site undergoes conformational changes coupled to voltage-dependent gating, which may be sensitive to oxidative stress. The main results show that internally applied nitric oxide (NO) inhibits channel activity profoundly. This inhibition is reversed by reduced glutathione and suppressed by intracellular Zn(2+), and at least two Zn(2+) site cysteines are required to observe the NO-induced inhibition (Cys-110 from one subunit and Cys-132 from the neighboring subunit). Biochemical evidence suggests strongly that NO induces a disulfide bridge between Cys-110 and Cys-132 in intact cells. Finally, further mutational studies suggest that intra-subunit Zn(2+) coordination involving His-104, Cys-131, and Cys-132 protects against the formation of the inhibitory disulfide bond. We propose that the interfacial T1 Zn(2+) site of Kv4 channels acts as a Zn(2+)-dependent redox switch that may regulate the activity of neuronal and cardiac A-type K(+) currents under physiological and pathological conditions.

  4. Intracellular diagnostics: hunting for the mode of action of redox-modulating selenium compounds in selected model systems.

    PubMed

    Mániková, Dominika; Letavayová, Lucia Medvecová; Vlasáková, Danuša; Košík, Pavol; Estevam, Ethiene Castellucci; Nasim, Muhammad Jawad; Gruhlke, Martin; Slusarenko, Alan; Burkholz, Torsten; Jacob, Claus; Chovanec, Miroslav

    2014-08-13

    Redox-modulating compounds derived from natural sources, such as redox active secondary metabolites, are currently of considerable interest in the field of chemoprevention, drug and phytoprotectant development. Unfortunately, the exact and occasionally even selective activity of such products, and the underlying (bio-)chemical causes thereof, are often only poorly understood. A combination of the nematode- and yeast-based assays provides a powerful platform to investigate a possible biological activity of a new compound and also to explore the "redox link" which may exist between its activity on the one side and its chemistry on the other. Here, we will demonstrate the usefulness of this platform for screening several selenium and tellurium compounds for their activity and action. We will also show how the nematode-based assay can be used to obtain information on compound uptake and distribution inside a multicellular organism, whilst the yeast-based system can be employed to explore possible intracellular mechanisms via chemogenetic screening and intracellular diagnostics. Whilst none of these simple and easy-to-use assays can ultimately substitute for in-depth studies in human cells and animals, these methods nonetheless provide a first glimpse on the possible biological activities of new compounds and offer direction for more complicated future investigations. They may also uncover some rather unpleasant biochemical actions of certain compounds, such as the ability of the trace element supplement selenite to induce DNA strand breaks.

  5. Cellular Senescence, Neurological Function, and Redox State.

    PubMed

    Maciel-Barón, Luis Ángel; Moreno-Blas, Daniel; Morales-Rosales, Sandra Lizbeth; González-Puertos, Viridiana Yazmín; López-Díazguerrero, Norma Edith; Torres, Claudio; Castro-Obregón, Susana; Königsberg, Mina

    2017-06-08

    Cellular senescence, characterized by permanent cell cycle arrest, has been extensively studied in mitotic cells such as fibroblasts. However, senescent cells have also been observed in the brain. Even though it is recognized that cellular energetic metabolism and redox homeostasis are perturbed in the aged brain and neurodegenerative diseases (NDDs), it is still unknown which alterations in the overall physiology can stimulate cellular senescence induction and their relationship with the former events. Recent Advances: Recent findings have shown that during prolonged inflammatory and pathologic events, the blood-brain barrier could be compromised and immune cells might enter the brain; this fact along with the brain's high oxygen dependence might result in oxidative damage to macromolecules and therefore senescence induction. Thus, cellular senescence in different brain cell types is revised here. Most information related to cellular senescence in the brain has been obtained from research in glial cells since it has been assumed that the senescent phenotype is a feature exclusive to mitotic cells. Nevertheless, neurons with senescence hallmarks have been observed in old mouse brains. Therefore, although this is a controversial topic in the field, here we summarize and integrate the observations from several studies and propose that neurons indeed senesce. It is still unknown which alterations in the overall metabolism can stimulate senescence induction in the aged brain, what are the mechanisms and signaling pathways, and what is their relationship to NDD development. The understanding of these processes will expose new targets to intervene age-associated pathologies.-Antioxid. Redox Signal. 00, 000-000.

  6. Smart pH/Redox Dual-Responsive Nanogels for On-Demand Intracellular Anticancer Drug Release.

    PubMed

    Yang, Hao; Wang, Qin; Huang, Shan; Xiao, Ai; Li, Fuying; Gan, Lu; Yang, Xiangliang

    2016-03-01

    Efficient accumulation and intracellular drug release in cancer cells remain a crucial challenge in developing ideal anticancer drug delivery systems. Here, poly(N-isopropylacrylamide)-ss-acrylic acid (P(NIPAM-ss-AA)) nanogels based on NIPAM and AA cross-linked by N,N'-bis(acryloyl)cystamine (BAC) were constructed by precipitation polymerization. The nanogels exhibited pH/redox dual responsive doxorubicin (DOX) release behavior in vitro and in tumor cells, in which DOX release from nanogels was accelerated in lysosomal pH (pH 4.5) and cytosolic reduction (10 mM GSH) conditions. Moreover, intracellular tracking of DOX-loaded nanogels confirmed that after the nanogels and the loaded DOX entered the cells simultaneously mainly via lipid raft/caveolae-mediated endocytosis, DOX-loaded nanogels were transported to lysosomes and then the loaded DOX was released to nucleus triggered by lysosomal pH and cytoplasmic high GSH. MTT analysis showed that DOX-loaded nanogels could efficiently inhibit the proliferation of HepG2 cells. In vivo animal studies demonstrated that DOX-loaded nanogels were accumulated and penetrated in tumor tissues more efficiently than free DOX. Meanwhile, DOX-loaded nanogels exhibited stronger tumor inhibition activity and fewer side effects. This study indicated that pH/redox dual-responsive nanogels might present a prospective platform for intracellular drug controlled release in cancer therapy.

  7. A Low Glutathione Redox State Couples with a Decreased Ascorbate Redox Ratio to Accelerate Flowering in Oncidium Orchid.

    PubMed

    Chin, Dan-Chu; Hsieh, Chia-Chi; Lin, Hsin-Yi; Yeh, Kai-Wun

    2016-02-01

    Glutathione (GSH) plays multiple roles in plants, including stress defense and regulation of growth/development. Previous studies have demonstrated that the ascorbate (AsA) redox state is involved in flowering initiation in Oncidium orchid. In this study, we discovered that a significantly decreased GSH content and GSH redox ratio are correlated with a decline in the AsA redox state during flowering initiation and high ambient temperature-induced flowering. At the same time, the expression level and enzymatic activity of GSH redox-regulated genes, glutathione reductase (GR1), and the GSH biosynthesis genes γ-glutamylcysteine synthetase (GSH1) and glutathione synthase (GSH2), are down-regulated. Elevating dehydroascorbate (DHA) content in Oncidium by artificial addition of DHA resulted in a decreased AsA and GSH redox ratio, and enhanced dehydroascorbate reductase (DHAR) activity. This demonstrated that the lower GSH redox state could be influenced by the lower AsA redox ratio. Moreover, exogenous application of buthionine sulfoximine (BSO), to inhibit GSH biosynthesis, and glutathione disulfide (GSSG), to decrease the GSH redox ratio, also caused early flowering. However, spraying plants with GSH increased the GSH redox ratio and delayed flowering. Furthermore, transgenic Arabidopsis overexpressing Oncidium GSH1, GSH2 and GR1 displayed a high GSH redox ratio as well as delayed flowering under high ambient temperature treatment, while pad2, cad2 and gr1 mutants exhibited early flowering and a low GSH redox ratio. In conclusion, our results provide evidence that the decreased GSH redox state is linked to the decline in the AsA redox ratio and mediated by down-regulated expression of GSH metabolism-related genes to affect flowering time in Oncidium orchid.

  8. The Aer protein and the serine chemoreceptor Tsr independently sense intracellular energy levels and transduce oxygen, redox, and energy signals for Escherichia coli behavior

    PubMed Central

    Rebbapragada, Anuradha; Johnson, Mark S.; Harding, Gordon P.; Zuccarelli, Anthony J.; Fletcher, Hansel M.; Zhulin, Igor B.; Taylor, Barry L.

    1997-01-01

    We identified a protein, Aer, as a signal transducer that senses intracellular energy levels rather than the external environment and that transduces signals for aerotaxis (taxis to oxygen) and other energy-dependent behavioral responses in Escherichia coli. Domains in Aer are similar to the signaling domain in chemotaxis receptors and the putative oxygen-sensing domain of some transcriptional activators. A putative FAD-binding site in the N-terminal domain of Aer shares a consensus sequence with the NifL, Bat, and Wc-1 signal-transducing proteins that regulate gene expression in response to redox changes, oxygen, and blue light, respectively. A double mutant deficient in aer and tsr, which codes for the serine chemoreceptor, was negative for aerotaxis, redox taxis, and glycerol taxis, each of which requires the proton motive force and/or electron transport system for signaling. We propose that Aer and Tsr sense the proton motive force or cellular redox state and thereby integrate diverse signals that guide E. coli to environments where maximal energy is available for growth. PMID:9380671

  9. Model-driven intracellular redox status modulation for increasing isobutanol production in Escherichia coli.

    PubMed

    Liu, Jiao; Qi, Haishan; Wang, Cheng; Wen, Jianping

    2015-01-01

    Few strains have been found to produce isobutanol naturally. For building a high performance isobutanol-producing strain, rebalancing redox status of the cell was very crucial through systematic investigation of redox cofactors metabolism. Then, the metabolic model provided a powerful tool for the rational modulation of the redox status. Firstly, a starting isobutanol-producing E. coli strain LA02 was engineered with only 2.7 g/L isobutanol produced. Then, the genome-scale metabolic modeling was specially carried out for the redox cofactor metabolism of the strain LA02 by combining flux balance analysis and minimization of metabolic adjustment, and the GAPD reaction catalyzed by the glyceraldehyde-3-phosphate dehydrogenase was predicted as the key target for redox status improvement. Under guidance of the metabolic model prediction, a gapN-encoding NADP(+) dependent glyceraldehyde-3-phosphate dehydrogenase pathway was constructed and then fine-tuned using five constitutive promoters. The best strain LA09 was obtained with the strongest promoter BBa_J23100. The NADPH/NADP + ratios of strain LA09 reached 0.67 at exponential phase and 0.64 at stationary phase. The redox modulations resulted in the decrease production of ethanol and lactate by 17.5 and 51.7% to 1.32 and 6.08 g/L, respectively. Therefore, the isobutanol titer was increased by 221% to 8.68 g/L. This research has achieved rational redox status improvement of isobutanol-producing strain under guidance of the prediction and modeling of the genome-scale metabolic model of isobutanol-producing E. coli strain with the aid of synthetic promoters. Therefore, the production of isobutanol was dramatically increased by 2.21-fold from 2.7 to 8.68 g/L. Moreover, the developed model-driven method special for redox cofactor metabolism was of very helpful to the redox status modulation of other bio-products.

  10. Intracellular glasses and seed survival in the dry state.

    PubMed

    Buitink, Julia; Leprince, Olivier

    2008-10-01

    So-called orthodox seeds can resist complete desiccation and survive the dry state for extended periods of time. During drying, the cellular viscosity increases dramatically and in the dry state, the cytoplasm transforms into a glassy state. The formation of intracellular glasses is indispensable to survive the dry state. Indeed, the storage stability of seeds is related to the packing density and molecular mobility of the intracellular glass, suggesting that the physico-chemical properties of intracellular glasses provide stability for long-term survival. Whereas seeds contain large amounts of soluble non-reducing sugars, which are known to be good glass formers, detailed in vivo measurements using techniques such as FTIR and EPR spectroscopy reveal that these intracellular glasses have properties that are quite different from those of simple sugar glasses. Intracellular glasses exhibit slow molecular mobility and a high molecular packing, resembling glasses made of mixtures of sugars with proteins, which potentially interact with additional cytoplasmic components such as salts, organic acids and amino acids. Above the glass transition temperature, the cytoplasm of biological systems still exhibits a low molecular mobility and a high stability, which serves as an ecological advantage, keeping the seeds stable under adverse conditions of temperature or water content that bring the tissues out of the glassy state.

  11. Contrasting effects of intracellular redox couples on the regulation of maxi-K channels in isolated myocytes from rabbit pulmonary artery.

    PubMed Central

    Thuringer, D; Findlay, I

    1997-01-01

    1. The effects of intracellular redox couples were investigated on the activation by voltage, Ca2+ and NS 1619 of maxi-K channels in enzymatically isolated smooth muscle cells from large pulmonary arteries of rabbits. 2. In inside-out membrane patches, maxi-K channels were characterized by a single-channel conductance of 266 pS in symmetrical 140 mM KCl solutions. The relationship between the open-state probability (Po) and the membrane potential could be fitted to the Boltzmann equation. The activating action of intracellular Ca2+ was reversible, concentration dependent, and was manifested as the reduction in the voltage necessary to half-activate the channel (V1/2) with no change in the slope factor. NS 1619 also predisposed the maxi-K channel to open at more hyperpolarized membrane potentials. 3. The oxidizing agent 5,5'-dithio-bis(2-nitrobenzoic acid) (DTNB, 1 mM) activated maxi-K channels by inducing a negative shift of the activity-voltage curve, while the reducing agent 2-hydroxy-1-ethanethiol (beta-mercaptoethanol) (BME, 1 mM) had no effect. DTNB increased the efficacy of Ca2+ in activating maxi-K channels. The action of DTNB was not reversible upon wash-out, but could be counteracted by BME. 4. Maxi-K channel activity was unaffected by other oxidizing agents, such as NAD (2 mM) and glutathione disulphide (GSSG, 5 mM), or by their reduced forms (NADH and GSH). Mg-ATP (0.1 and 1 mM) increased the channel activity in a dose-dependent manner, while guanine nucleotides (100 microM GTP gamma S, 500 microM GDP and 200 microM GDP beta S) had no effect. 5. Our data suggest that a change in the intracellular redox state, which would be expected during acute hypoxia, does not alter the activity of maxi-K channels of large pulmonary artery smooth muscle cells. The sulfhydryl-specific redox reagents (DTNB and BME) must act through another regulatory mechanism. PMID:9161977

  12. Contrasting effects of intracellular redox couples on the regulation of maxi-K channels in isolated myocytes from rabbit pulmonary artery.

    PubMed

    Thuringer, D; Findlay, I

    1997-05-01

    1. The effects of intracellular redox couples were investigated on the activation by voltage, Ca2+ and NS 1619 of maxi-K channels in enzymatically isolated smooth muscle cells from large pulmonary arteries of rabbits. 2. In inside-out membrane patches, maxi-K channels were characterized by a single-channel conductance of 266 pS in symmetrical 140 mM KCl solutions. The relationship between the open-state probability (Po) and the membrane potential could be fitted to the Boltzmann equation. The activating action of intracellular Ca2+ was reversible, concentration dependent, and was manifested as the reduction in the voltage necessary to half-activate the channel (V1/2) with no change in the slope factor. NS 1619 also predisposed the maxi-K channel to open at more hyperpolarized membrane potentials. 3. The oxidizing agent 5,5'-dithio-bis(2-nitrobenzoic acid) (DTNB, 1 mM) activated maxi-K channels by inducing a negative shift of the activity-voltage curve, while the reducing agent 2-hydroxy-1-ethanethiol (beta-mercaptoethanol) (BME, 1 mM) had no effect. DTNB increased the efficacy of Ca2+ in activating maxi-K channels. The action of DTNB was not reversible upon wash-out, but could be counteracted by BME. 4. Maxi-K channel activity was unaffected by other oxidizing agents, such as NAD (2 mM) and glutathione disulphide (GSSG, 5 mM), or by their reduced forms (NADH and GSH). Mg-ATP (0.1 and 1 mM) increased the channel activity in a dose-dependent manner, while guanine nucleotides (100 microM GTP gamma S, 500 microM GDP and 200 microM GDP beta S) had no effect. 5. Our data suggest that a change in the intracellular redox state, which would be expected during acute hypoxia, does not alter the activity of maxi-K channels of large pulmonary artery smooth muscle cells. The sulfhydryl-specific redox reagents (DTNB and BME) must act through another regulatory mechanism.

  13. Fc-receptor-mediated intracellular delivery of Cu/Zn-superoxide dismutase (SOD1) protects against redox-induced apoptosis through a nitric oxide dependent mechanism.

    PubMed Central

    Vouldoukis, I.; Sivan, V.; Vozenin, M. C.; Kamaté, C.; Calenda, A.; Mazier, D.; Dugas, B.

    2000-01-01

    BACKGROUND: Using specific antibodies against bovine Cu/Zn-superoxide dismutase (EC 1.15.1.1, SOD1) we demonstrated that anti-SOD antibodies (IgG1) are able to promote the intracellular translocation of the antioxidant enzyme. The transduction signalling mediated by IgG1 immune complexes are known to promote a concomitant production of superoxide and nitric oxide leading to the production of peroxynitrites and cell death by apoptosis. The Fc-mediated intracellular delivery of SOD1 thus limited the endogenous production of superoxide. It was thus of interest to confirm that in the absence of superoxide anion, the production of nitric oxide protected cells against apoptosis. Study in greater detail clearly stated that under superoxide anion-free conditions, nitric oxide promoted the cell antioxidant armature and thus protected cells against redox-induced apoptosis. MATERIALS AND METHODS: The murine macrophage cell-lines J774 A1 were preactivated or not with interferon-gamma and were then stimulated by IgG1 immune complexes (IC), free SOD1 or SOD1 IC and superoxide anion, nitric oxide, peroxynitrite, and tumor necrosis factor-alpha (TNF-alpha) production was evaluated. The redox consequences of these activation processes were also evaluated on mitochondrial respiration and apoptosis as well as on the controlled expression of the cellular antioxidant armature. RESULTS: We demonstrated that SOD1 IC induced a Fcgamma receptor (FcgammaR)-dependent intracellular delivery of the antioxidant enzyme in IFN-gamma activated murine macrophages (the J774 AI cell line). The concomitant stimulation of the FcyR and the translocation of the SOD1 in the cytoplasm of IFN-gamma-activated macrophages not only reduced the production of superoxide anion but also induced the expression of the inducible form of nitric oxide synthase (iNOS) and the related NO production. This inducing effect in the absence of superoxide anion production reduced mitochondrial damages and cell death by

  14. Direct Determination of the Intracellular Oxidation State of Plutonium

    PubMed Central

    Gorman-Lewis, Drew; Aryal, Baikuntha P.; Paunesku, Tatjana; Vogt, Stefan; Lai, Barry; Woloschak, Gayle E.; Jensen, Mark P.

    2013-01-01

    Microprobe X-ray absorption near edge structure (μ-XANES) measurements were used to determine directly, for the first time, the oxidation state of intracellular plutonium in individual 0.1 μm2 areas within single rat pheochromocytoma cells (PC12). The living cells were incubated in vitro for 3 hours in the presence of Pu added to the media in different oxidation states (Pu(III), Pu(IV), and Pu(VI)) and in different chemical forms. Regardless of the initial oxidation state or chemical form of Pu presented to the cells, the XANES spectra of the intracellular Pu deposits was always consistent with tetravalent Pu even though the intracellular milieu is generally reducing. PMID:21755934

  15. Biological validation of coenzyme Q redox state by HPLC-EC measurement: relationship between coenzyme Q redox state and coenzyme Q content in rat tissues.

    PubMed

    Galinier, A; Carrière, A; Fernandez, Y; Bessac, A M; Caspar-Bauguil, S; Periquet, B; Comtat, M; Thouvenot, J P; Casteilla, L

    2004-12-03

    The properties of coenzymes Q (CoQ9 and CoQ10) are closely linked to their redox state (CoQox/total CoQ) x 100. In this work, CoQ redox state was biologically validated by high performance liquid chromatography-electrochemical measurement after modulation of mitochondrial electron flow of cultured cells by molecules increasing (rotenone, carbonyl cyanide chlorophenylhydrazone) or decreasing (antimycin) CoQ oxidation. The tissue specificity of CoQ redox state and content were investigated in control and hypoxic rats. In control rats, there was a strong negative linear regression between tissular CoQ redox state and CoQ content. Hypoxia increased CoQ9 redox state and decreased CoQ9 content in a negative linear relationship in the different tissues, except the heart and lung. This result demonstrates that, under conditions of mitochondrial impairment, CoQ redox control is tissue-specific.

  16. Redox state of earth's upper mantle from kimberlitic ilmenites

    NASA Technical Reports Server (NTRS)

    Haggerty, S. E.; Tompkins, L. A.

    1983-01-01

    Temperatures and oxygen fugacities are reported on discrete ilmenite nodules in kimberlites from West Africa which demonstrate that the source region in the upper mantle is moderately oxidized, consistent with other nodule suites in kimberlites from southern Africa and the United States. A model is presented for a variety of tectonic settings, proposing that the upper mantle is profiled in redox potential, oxidized in the fertile asthenosphere but reduced in the depleted lithosphere.

  17. Extracellular Redox Regulation of Intracellular Reactive Oxygen Generation, Mitochondrial Function and Lipid Turnover in Cultured Human Adipocytes

    PubMed Central

    Oliveira, Marcus F.; Burritt, Nathan; Corkey, Barbara E.

    2016-01-01

    Background Many tissues play an important role in metabolic homeostasis and the development of diabetes and obesity. We hypothesized that the circulating redox metabolome is a master metabolic regulatory system that impacts all organs and modulates reactive oxygen species (ROS) production, lipid peroxidation, energy production and changes in lipid turnover in many cells including adipocytes. Methods Differentiated human preadipocytes were exposed to the redox couples, lactate (L) and pyruvate (P), β–hydroxybutyrate (βOHB) and acetoacetate (Acoc), and the thiol-disulfides cysteine/ cystine (Cys/CySS) and GSH/GSSG for 1.5–4 hours. ROS measurements were done with CM-H2DCFDA. Lipid peroxidation (LPO) was assessed by a modification of the thiobarbituric acid method. Lipolysis was measured as glycerol release. Lipid synthesis was measured as 14C-glucose incorporated into lipid. Respiration was assessed using the SeaHorse XF24 analyzer and the proton leak was determined from the difference in respiration with oligomycin and antimycin A. Results Metabolites with increasing oxidation potentials (GSSG, CySS, Acoc) increased adipocyte ROS. In contrast, P caused a decrease in ROS compared with L. Acoc also induced a significant increase in both LPO and lipid synthesis. L and Acoc increased lipolysis. βOHB increased respiration, mainly due to an increased proton leak. GSSG, when present throughout 14 days of differentiation significantly increased fat accumulation, but not when added later. Conclusions We demonstrated that in human adipocytes changes in the external redox state impacted ROS production, LPO, energy efficiency, lipid handling, and differentiation. A more oxidized state generally led to increased ROS, LPO and lipid turnover and more reduction led to increased respiration and a proton leak. However, not all of the redox couples were the same suggesting compartmentalization. These data are consistent with the concept of the circulating redox metabolome as a

  18. Kinetics and intracellular location of intramolecular disulfide bond formation mediated by the cytoplasmic redox system encoded by vaccinia virus

    SciTech Connect

    Bisht, Himani; Brown, Erica; Moss, Bernard

    2010-03-15

    Poxviruses encode a redox system for intramolecular disulfide bond formation in cytoplasmic domains of viral proteins. Our objectives were to determine the kinetics and intracellular location of disulfide bond formation. The vaccinia virus L1 myristoylated membrane protein, used as an example, has three intramolecular disulfide bonds. Reduced and disulfide-bonded forms of L1 were distinguished by electrophoretic mobility and reactivity with monoclonal and polyclonal antibodies. Because disulfide bonds formed during 5 min pulse labeling with radioactive amino acids, a protocol was devised in which dithiothreitol was present at this step. Disulfide bond formation was detected by 2 min after removal of reducing agent and was nearly complete in 10 min. When the penultimate glycine residue was mutated to prevent myristoylation, L1 was mistargeted to the endoplasmic reticulum and disulfide bond formation failed to occur. These data suggested that viral membrane association was required for oxidation of L1, providing specificity for the process.

  19. Ethanol Attenuates Histiotrophic Nutrition Pathways and Alters the Intracellular Redox Environment and Thiol Proteome during Rat Organogenesis

    PubMed Central

    Jilek, Joseph L.; Sant, Karilyn E.; Cho, Katherine H.; Reed, Matthew S.; Pohl, Jan; Hansen, Jason M.; Harris, Craig

    2015-01-01

    Ethanol (EtOH) is a reactive oxygen-generating teratogen involved in the etiology of structural and functional developmental defects. Embryonic nutrition, redox environment, and changes in the thiol proteome following EtOH exposures (1.56.0 mg/ml) were studied in rat whole embryo culture. Glutathione (GSH) and cysteine (Cys) concentrations with their respective intracellular redox potentials (Eh) were determined using high-performance liquid chromatography. EtOH reduced GSH and Cys concentrations in embryo (EMB) and visceral yolk sac (VYS) tissues, and also in yolk sac and amniotic fluids. These changes produced greater oxidation as indicated by increasingly positive Eh values. EtOH reduced histiotrophic nutrition pathway activities as measured by the clearance of fluorescin isothiocyanate (FITC)-albumin from culture media. A significant decrease in total FITC clearance was observed at all concentrations, reaching approximately 50% at the highest dose. EtOH-induced changes to the thiol proteome were measured in EMBs and VYSs using isotope-coded affinity tags. Decreased concentrations for specific proteins from cytoskeletal dynamics and endocytosis pathways (α-actinin, α-tubulin, cubilin, and actin-related protein 2); nuclear translocation (Ran and RanBP1); and maintenance of receptor-mediated endocytosis (cubilin) were observed. Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis also identified a decrease in ribosomal proteins in both EMB and VYS. Results show that EtOH interferes with nutrient uptake to reduce availability of amino acids and micronutrients required by the conceptus. Intracellular antioxidants such as GSH and Cys are depleted following EtOH and Eh values increase. Thiol proteome analysis in the EMB and VYS show selectively altered actin/cytoskeleton, endocytosis, ribosome biogenesis and function, nuclear transport, and stress-related responses. PMID:26185205

  20. Ethanol Attenuates Histiotrophic Nutrition Pathways and Alters the Intracellular Redox Environment and Thiol Proteome during Rat Organogenesis.

    PubMed

    Jilek, Joseph L; Sant, Karilyn E; Cho, Katherine H; Reed, Matthew S; Pohl, Jan; Hansen, Jason M; Harris, Craig

    2015-10-01

    Ethanol (EtOH) is a reactive oxygen-generating teratogen involved in the etiology of structural and functional developmental defects. Embryonic nutrition, redox environment, and changes in the thiol proteome following EtOH exposures (1.56.0 mg/ml) were studied in rat whole embryo culture. Glutathione (GSH) and cysteine (Cys) concentrations with their respective intracellular redox potentials (Eh) were determined using high-performance liquid chromatography. EtOH reduced GSH and Cys concentrations in embryo (EMB) and visceral yolk sac (VYS) tissues, and also in yolk sac and amniotic fluids. These changes produced greater oxidation as indicated by increasingly positive Eh values. EtOH reduced histiotrophic nutrition pathway activities as measured by the clearance of fluorescin isothiocyanate (FITC)-albumin from culture media. A significant decrease in total FITC clearance was observed at all concentrations, reaching approximately 50% at the highest dose. EtOH-induced changes to the thiol proteome were measured in EMBs and VYSs using isotope-coded affinity tags. Decreased concentrations for specific proteins from cytoskeletal dynamics and endocytosis pathways (α-actinin, α-tubulin, cubilin, and actin-related protein 2); nuclear translocation (Ran and RanBP1); and maintenance of receptor-mediated endocytosis (cubilin) were observed. Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis also identified a decrease in ribosomal proteins in both EMB and VYS. Results show that EtOH interferes with nutrient uptake to reduce availability of amino acids and micronutrients required by the conceptus. Intracellular antioxidants such as GSH and Cys are depleted following EtOH and Eh values increase. Thiol proteome analysis in the EMB and VYS show selectively altered actin/cytoskeleton, endocytosis, ribosome biogenesis and function, nuclear transport, and stress-related responses. © The Author 2015. Published by Oxford University Press on behalf of the Society of

  1. pH/redox dual-sensitive dextran nanogels for enhanced intracellular drug delivery.

    PubMed

    Curcio, Manuela; Diaz-Gomez, Luis; Cirillo, Giuseppe; Concheiro, Angel; Iemma, Francesca; Alvarez-Lorenzo, Carmen

    2017-08-01

    pH/redox dual-responsive nanogels (DEX-SS) were prepared by precipitation polymerization of methacrylated dextran (DEXMA), 2-aminoethylmethacrylate (AEMA) and N,N'-bis(acryloyl)cystamine (BAC), and then loaded with methotrexate (MTX). Nanogels were spherical and exhibited homogeneous size distribution (460nm, PDI<0.30) as observed using dynamic light scattering (DLS) and scanning electron microscopy (SEM). DEX-SS were sensitive to the variations of pH and redox environment. Nanogels incubated in buffer pH 5.0 containing 10mM glutathione (GSH) synergistically increased the mean diameter and the PDI to 750nm and 0.42, respectively. In vitro release experiments were performed at pH 7.4 and 5.0 with and without GSH. The cumulative release of MTX in pH 5.0 medium with 10mMGSH was 5-fold higher than that recorded at pH 7.4 without GSH. Fibroblasts and tumor cells were used to tests the effects of blank DEX-SS and MTX@DEX-SS nanogels on cell viability. Remarkable influence of pH on nanogels internalization into HeLa cells was evidenced by means of confocal microscopy and flow cytometry. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Artificial Enzyme-based Logic Operations to Mimic an Intracellular Enzyme-participated Redox Balance System.

    PubMed

    Huang, Yanyan; Pu, Fang; Ren, Jinsong; Qu, Xiaogang

    2017-07-06

    Owing to the biocatalytic properties of artificial enzymes and the redox characteristic of glutathione, a colorimetric and resettable biological operation was successfully designed to mimic enzyme-participated redox balance in living systems. As one promising candidate of a natural enzyme, artificial enzyme possesses many advantages and has been used in numerous fields. Similar to natural enzymes, communications are also present between different artificial enzymes. With the assistance of four artificial enzymes, three simple biological logic gates were fabricated to help us deepen the understanding of communications between artificial enzymes. In the presence of glutathione, the system could be easily reset without any complicated procedures. We prospect that this work may push forward the exploration of communications between different artificial enzymes and the design of novel artificial enzyme-based biological gates or nanodevices. We hope that our mimic system may help us further understand the functioning of complex biological pathways in biological systems. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. An intracellular redox sensor for reactive oxygen species at the M3-M4 linker of GABAAρ1 receptors

    PubMed Central

    Beltrán González, Andrea N; Gasulla, Javier; Calvo, Daniel J

    2014-01-01

    Background and Purpose Reactive oxygen species (ROS) are normally involved in cell oxidative stress but also play a role as cellular messengers in redox signalling; for example, modulating the activity of neurotransmitter receptors and ion channels. However, the direct actions of ROS on GABAA receptors were not previously demonstrated. In the present work, we studied the effects of ROS on GABAAρ1 receptor function. Experimental Approach GABAAρ1 receptors were expressed in oocytes and GABA-evoked responses electrophysiologically recorded in the presence or absence of ROS. Chemical protection of cysteines by selective sulfhydryl reagents and site-directed mutagenesis studies were used to identify protein residues involved in ROS actions. Key Results GABAAρ1 receptor-mediated responses were significantly enhanced in a concentration-dependent and reversible manner by H2O2. Potentiating effects were attenuated by a free radical scavenger, lipoic acid or an inhibitor of the Fenton reaction, deferoxamine. Each ρ1 subunit contains only three cysteine residues, two extracellular at the Cys-loop (C177 and C191) and one intracellular (C364) at the M3-M4 linker. Mutant GABAAρ1 receptors in which C364 was exchanged by alanine were completely insensitive to modulation, implying that this site, rather than a cysteine in the Cys-loop, is essential for ROS modulation. Conclusion and Implications Our results show that the function of GABAAρ1 receptors is enhanced by ROS and that the intracellular C364 is the sensor for ROS actions. PMID:24428763

  4. Glutathione redox potential in the mitochondrial intermembrane space is linked to the cytosol and impacts the Mia40 redox state

    PubMed Central

    Kojer, Kerstin; Bien, Melanie; Gangel, Heike; Morgan, Bruce; Dick, Tobias P; Riemer, Jan

    2012-01-01

    Glutathione is an important mediator and regulator of cellular redox processes. Detailed knowledge of local glutathione redox potential (EGSH) dynamics is critical to understand the network of redox processes and their influence on cellular function. Using dynamic oxidant recovery assays together with EGSH-specific fluorescent reporters, we investigate the glutathione pools of the cytosol, mitochondrial matrix and intermembrane space (IMS). We demonstrate that the glutathione pools of IMS and cytosol are dynamically interconnected via porins. In contrast, no appreciable communication was observed between the glutathione pools of the IMS and matrix. By modulating redox pathways in the cytosol and IMS, we find that the cytosolic glutathione reductase system is the major determinant of EGSH in the IMS, thus explaining a steady-state EGSH in the IMS which is similar to the cytosol. Moreover, we show that the local EGSH contributes to the partially reduced redox state of the IMS oxidoreductase Mia40 in vivo. Taken together, we provide a comprehensive mechanistic picture of the IMS redox milieu and define the redox influences on Mia40 in living cells. PMID:22705944

  5. Fluoroquinolones lower constitutive H2AX and ATM phosphorylation in TK6 lymphoblastoid cells via modulation of the intracellular redox status.

    PubMed

    Halicka, H Dorota; Smart, Daniel J; Traganos, Frank; Williams, Gary M; Darzynkiewicz, Zbigniew

    2009-01-01

    Accumulation of reactive oxygen species (ROS)-induced damage and mutations in the genomic DNA is considered the primary etiology of aging and age-related pathologies including cancer. Strategies aimed at slowing these conditions often involve protecting against oxidative DNA damage via modulation of the intracellular redox state. Recently, a biomarker of DNA double-strand breaks (DSBs), serine 139-phosphorylated histone H2AX (gammaH2AX), and its upstream mediator, activated PI-3-related kinase, ATM (ATM(P1981)), were shown to be constitutively expressed in cells and modulated by antioxidant treatment. Thus, both constitutive histone H2AX phosphorylation (CHP) and constitutive ATM activation (CAA) are thought to reflect a cell's response to endogenous ROS-induced DSBs. In the present study, we investigated the effects of a battery of fluoroquinolone (FQ) compounds, namely ciprofloxacin, enrofloxacin, gatifloxacin, lomefloxacin and ofloxacin, on CHP and CAA in human TK6 lymphoblastoid cells. All FQs tested reduced CHP and CAA compared to controls following 6 and 24 h treatment with CAA being more sensitive to their effects at both time points. In addition, intracellular ROS levels and mitochondrial activities were also lowered in FQ-treated cells at 6 and 24 h.We presume that FQs mediate this effect via a combination of ROS-scavenging and mitochondrial suppression and therefore may protect against the onset or may slow the progression of numerous oxidative pathophysiological conditions.

  6. The redox switch/redox coupling hypothesis.

    PubMed

    Cerdán, Sebastián; Rodrigues, Tiago B; Sierra, Alejandra; Benito, Marina; Fonseca, Luis L; Fonseca, Carla P; García-Martín, María L

    2006-01-01

    We provide an integrative interpretation of neuroglial metabolic coupling including the presence of subcellular compartmentation of pyruvate and monocarboxylate recycling through the plasma membrane of both neurons and glial cells. The subcellular compartmentation of pyruvate allows neurons and astrocytes to select between glucose and lactate as alternative substrates, depending on their relative extracellular concentration and the operation of a redox switch. This mechanism is based on the inhibition of glycolysis at the level of glyceraldehyde 3-phosphate dehydrogenase by NAD(+) limitation, under sufficiently reduced cytosolic NAD(+)/NADH redox conditions. Lactate and pyruvate recycling through the plasma membrane allows the return to the extracellular medium of cytosolic monocarboxylates enabling their transcellular, reversible, exchange between neurons and astrocytes. Together, intracellular pyruvate compartmentation and monocarboxylate recycling result in an effective transcellular coupling between the cytosolic NAD(+)/NADH redox states of both neurons and glial cells. Following glutamatergic neurotransmission, increased glutamate uptake by the astrocytes is proposed to augment glycolysis and tricarboxylic acid cycle activity, balancing to a reduced cytosolic NAD(+)/NADH in the glia. Reducing equivalents are transferred then to the neuron resulting in a reduced neuronal NAD(+)/NADH redox state. This may eventually switch off neuronal glycolysis, favoring the oxidation of extracellular lactate in the lactate dehydrogenase (LDH) equilibrium and in the neuronal tricarboxylic acid cycles. Finally, pyruvate derived from neuronal lactate oxidation, may return to the extracellular space and to the astrocyte, restoring the basal redox state and beginning a new loop of the lactate/pyruvate transcellular coupling cycle. Transcellular redox coupling operates through the plasma membrane transporters of monocarboxylates, similarly to the intracellular redox shuttles

  7. Mitochondrial cytochrome redox states and respiration in acute pulmonary oxygen sensing.

    PubMed

    Sommer, N; Pak, O; Schörner, S; Derfuss, T; Krug, A; Gnaiger, E; Ghofrani, H A; Schermuly, R T; Huckstorf, C; Seeger, W; Grimminger, F; Weissmann, N

    2010-11-01

    Hypoxic pulmonary vasoconstriction (HPV) is an essential mechanism to optimise lung gas exchange. We aimed to decipher the proposed oxygen sensing mechanism of mitochondria in HPV. Cytochrome redox state was assessed by remission spectrophotometry in intact lungs and isolated pulmonary artery smooth muscle cells (PASMC). Mitochondrial respiration was quantified by high-resolution respirometry. Alterations were compared with HPV and hypoxia-induced functional and molecular readouts on the cellular level. Aortic and renal arterial smooth muscle cells (ASMC and RASMC, respectively) served as controls. The hypoxia-induced decrease of mitochondrial respiration paralleled HPV in isolated lungs. In PASMC, reduction of respiration and mitochondrial cytochrome c and aa3 (complex IV), but not of cytochrome b (complex III) matched an increase in matrix superoxide levels as well as mitochondrial membrane hyperpolarisation with subsequent cytosolic calcium increase. In contrast to PASMC, RASMC displayed a lower decrease in respiration and no rise in superoxide, membrane potential or intracellular calcium. Pharmacological inhibition of mitochondria revealed analogous kinetics of cytochrome redox state and strength of HPV. Our data suggest inhibition of complex IV as an essential step in mitochondrial oxygen sensing of HPV. Concomitantly, increased superoxide release from complex III and mitochondrial membrane hyperpolarisation may initiate the cytosolic calcium increase underlying HPV.

  8. Thiol switches in redox regulation of chloroplasts: balancing redox state, metabolism and oxidative stress.

    PubMed

    Dietz, Karl-Josef; Hell, Rüdiger

    2015-05-01

    In photosynthesizing chloroplasts, rapidly changing energy input, intermediate generation of strong reductants as well as oxidants and multiple participating physicochemical processes and pathways, call for efficient regulation. Coupling redox information to protein function via thiol modifications offers a powerful mechanism to activate, down-regulate and coordinate interdependent processes. Efficient thiol switching of target proteins involves the thiol-disulfide redox regulatory network, which is highly elaborated in chloroplasts. This review addresses the features of this network. Its conditional function depends on specificity of reduction and oxidation reactions and pathways, thiol redox buffering, but also formation of heterogeneous milieus by microdomains, metabolite gradients and macromolecular assemblies. One major player is glutathione. Its synthesis and function is under feedback redox control. The number of thiol-controlled processes and involved thiol switched proteins is steadily increasing, e.g., in tetrapyrrole biosynthesis, plastid transcription and plastid translation. Thus chloroplasts utilize an intricate and versatile redox regulatory network for intraorganellar and retrograde communication.

  9. Dietary nucleotides enhance the liver redox state and protein synthesis in cirrhotic rats.

    PubMed

    Pérez, María José; Sánchez-Medina, Fermín; Torres, Maribel; Gil, Angel; Suárez, Antonio

    2004-10-01

    Cirrhosis is characterized by altered lipid and protein metabolism and an excessive accumulation of extracellular matrix components. The aim of this work was to determine the effect of dietary nucleotide intake on the intracellular pools of nucleic acids and nucleotides, hepatic redox state, and protein synthesis during cirrhosis. Rats were given 300 mg/L thioacetamide (TAA) in drinking water and were fed diets without (TAA-Nt) or with nucleotides (Nt) (TAA+Nt, 3 g each of AMP, inosine 5'-monophosphate, CMP, GMP, and UMP per kg diet) for 4 mo. The degree of liver histological injury was less in group TAA+Nt than in TAA-Nt. The intake of nucleotides significantly increased the hepatic concentration of total nucleotides, adenine nucleotides, and ATP+ADP+AMP. Interestingly, the concentration of CDP-choline, a nucleotide necessary for phospholipid synthesis, was significantly higher in TAA+Nt than in TAA-Nt. The hepatic pyruvate:lactate (P = 0.075) and acetoacetate:beta-hydrodybutyrate (P < 0.05) ratios, indicators of cytosolic and mitochondrial redox states, were lower in TAA-Nt than in TAA+Nt. The total protein concentration was higher in the livers of TAA+Nt than in TAA-Nt. Although there were no differences in the expression of the albumin gene, the hepatic albumin concentration was significantly higher in TAA+Nt than in TAA-Nt. These data indicate that the reduction of liver injury in nucleotide-supplemented rats may be due to the increased intracellular availability of key metabolic nucleotides, the restoration of mitochondrial function, and the augmentation of protein synthesis.

  10. Composition of Olivine, Melt Redox State, and Oxygen Fugacity

    NASA Astrophysics Data System (ADS)

    Barton, M.

    2003-12-01

    The compositions of ferro-magnesian silicates in equilibrium with melts are a function of oxygen fugacity. This was demonstrated experimentally in the case of olivine by Roeder and Emslie (1970). In principle, therefore, the composition of coexisting olivine and melt (with total Fe as FeO) allows melt redox state and hence oxygen fugacity to be calculated if the equilibrium distribution of Mg and Fe between olivine and melt is known. It has been found that the expression given by Gee and Sack (1988) accurately describes this distribution over a wide range of liquid compositions, so that melt redox state and oxygen fugacity can be calculated from the compositions of olivine-melt pairs. Oxygen fugacities have been calculated from published data for olivine-melt pairs produced in 160 experiments at 105 Pa at known oxygen fugacities (from 3 log units below to 7.6 log units above QFM) over a range of T from 1080 to 1339OC. Melt compositions in these experiments include tholeiitic and alkali-olivine basalts, picrites, andesites, and highly alkaline lavas (nephelinites, leucitites, ugandites). Forsterite compositions of olivines range from 0.98-0.55, whereas melt Mg-no's range from 0.75-0.25 (all Fe as FeO). There is excellent correlation (0.99) between calculated and experimental values. The maximum difference between calculated and experimental values is about 0.5 log units, but the average uncertainty (calculated at the 1-sigma level) is 0.24 log units. The results indicate that the expression given by Kress and Carmichael (1991) better describes the relationship between melt redox state and oxygen fugacity than that given by Kilinc et al. (1983). The results suggest that oxygen fugacities can be retrieved from coexisting olivine-melt pairs in natural samples. However, the non-linear relationship between olivine composition, melt ferric-ferrous iron ratio, and (log) oxygen fugacity indicates relatively large uncertainties at oxygen fugacities more reducing than about

  11. Donor/Acceptor Mixed Self-Assembled Monolayers for Realising a Multi-Redox-State Surface.

    PubMed

    Casado-Montenegro, Javier; Marchante, Elena; Crivillers, Núria; Rovira, Concepció; Mas-Torrent, Marta

    2016-06-17

    Mixed molecular self-assembled monolayers (SAMs) on gold, based on two types of electroactive molecules, that is, electron-donor (ferrocene) and electron-acceptor (anthraquinone) molecules, are prepared as an approach to realise surfaces exhibiting multiple accessible redox states. The SAMs are investigated in different electrolyte media. The nature of these media has a strong impact on the types of redox processes that take place and on the redox potentials. Under optimised conditions, surfaces with three redox states are achieved. Such states are accessible in a relatively narrow potential window in which the SAMs on gold are stable. This communication elucidates the key challenges in fabricating bicomponent SAMs as electrochemical switches.

  12. Redox state changes in human skeletal muscle after isometric contraction.

    PubMed Central

    Henriksson, J; Katz, A; Sahlin, K

    1986-01-01

    Subjects maintained an isometric contraction of the quadriceps femoris muscle at two-thirds maximal voluntary contraction (m.v.c.) force for 5 s (5.0 +/- 0.3 s; mean +/- S.E. of mean; n = 6) or until fatigue (52 +/- 4 s; n = 13). Muscle biopsies were obtained at rest, immediately after the contractions and also at 1 and 4 min of recovery after contraction to fatigue. In all subjects 5 s isometric contraction resulted in an increase of muscle NADH (0.084 +/- 0.012 at rest to 0.203 +/- 0.041 mmol/kg dry wt.) and a decrease of phosphocreatine (PC; change in concentration = -17.3 +/- 3.8 mmol/kg dry wt.). Glucose-6-phosphate concentration was more than doubled whereas lactate increased in only four of the six subjects. The two subjects who did not show any increase in lactate also had the lowest increase in NADH. At fatigue NADH increased to 0.226 +/- 0.032 mmol/kg dry wt. which was not significantly different from the value after 5 s contraction. Muscle PC was nearly depleted and lactate increased 12-fold above resting levels. The major part (65%) of the NADH increase at fatigue had reverted after 1 min recovery but only a slight further decrease occurred between 1 and 4 min of recovery. In relative terms the time course of the changes in muscle NADH during the first minute of recovery was similar to that of PC resynthesis, suggesting a common regulator such as O2 availability. In contrast to the delayed return of NADH concentration, PC resynthesis continued during the later part of the recovery period and PC concentration was almost fully restored after 4 min of recovery. It is concluded that muscle NADH is already maximally increased in the first seconds of muscle contraction at two-thirds m.v.c. Indirect evidence indicates that this increase reflects a reduction of the mitochondrial NAD-NADH redox couple. The rapid establishment of a reduced mitochondrial redox state at the start of muscle contraction will probably lead to a reduction of the redox state in the

  13. Regulation of soluble guanylyl cyclase redox state by hydrogen sulfide.

    PubMed

    Zhou, Zongmin; Martin, Emil; Sharina, Iraida; Esposito, Iolanda; Szabo, Csaba; Bucci, Mariarosaria; Cirino, Giuseppe; Papapetropoulos, Andreas

    2016-09-01

    Soluble guanylate cyclase (sGC) is a receptor for nitric oxide (NO). Binding of NO to ferrous (Fe(2+)) heme increases its catalytic activity, leading to the production of cGMP from GTP. Hydrogen sulfide (H2S) is a signaling molecule that exerts both direct and indirect anti-oxidant effects. In the present, study we aimed to determine whether H2S could regulate sGC redox state and affect its responsiveness to NO-releasing agents and sGC activators. Using cultured rat aortic smooth muscle cells, we observed that treatment with H2S augmented the response to the NO donor DEA/NO, while attenuating the response to the heme-independent activator BAY58-2667 that targets oxidized sGC. Similarly, overexpression of H2S-synthesizing enzyme cystathionine-γ lyase reduced the ability of BAY58-2667 to promote cGMP accumulation. In experiments with phenylephrine-constricted mouse aortic rings, treatment with rotenone (a compound that increases ROS production), caused a rightward shift of the DEA/NO concentration-response curve, an effect partially restored by H2S. When rings were pre-treated with H2S, the concentration-response curve to BAY 58-2667 shifted to the right. Using purified recombinant human sGC, we observed that treatment with H2S converted ferric to ferrous sGC enhancing NO-donor-stimulated sGC activity and reducing BAY 58-2667-triggered cGMP formation. The present study identified an additional mechanism of cross-talk between the NO and H2S pathways at the level of redox regulation of sGC. Our results provide evidence that H2S reduces sGC heme Fe, thus, facilitating NO-mediated cellular signaling events. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Multiple redox states of multiheme cytochromes may enable bacterial response to changing redox environments

    NASA Astrophysics Data System (ADS)

    Arbour, T.; Wrighton, K. C.; Mullin, S. W.; Castelle, C.; Luef, B.; Gilbert, B.; Banfield, J. F.

    2013-12-01

    Multiheme c-type cytochromes (MHCs) are key components in electron-transport pathways that enable some microorganisms to transfer electron byproducts of metabolism to a variety of minerals. As a response to changes in mineral redox potential, microbial communities may shift their membership, or individual organisms may adjust protein expression. Alternatively, the ability to respond may be conferred by the innate characteristics of certain electron-transport-chain components. Here, we used potentiostat-controlled microbial fuel cells (MFCs) to measure the timescale of response to imposed changes in redox conditions, thus placing constraints on the importance of these different mechanisms. In the experiments, a solid electrode acts as an electron-accepting mineral whose redox potential can be precisely controlled. We inoculated duplicate MFCs with a sediment/groundwater mixture from an aquifer at Rifle, Colorado, supplied acetate as an electron donor, and obtained stable, mixed-species biofilms dominated by Geobacter and a novel Geobacter-related family. We poised the anode at potentials spanning the range of natural Fe(III)-reduction, then performed cyclic voltammetry (CV) to characterize the overall biofilm redox signature. The apparent biofilm midpoint potential shifted directly with anode set potential when the latter was changed within the range from about -250 to -50 mV vs. SHE. Following a jump in set potential by 200 mV, the CV-midpoint shift by ~100 mV over a timescale of ~30 minutes to a few hours, depending on the direction of the potential change. The extracellular electron transfer molecules, whose overall CV signature is very similar to those of purified MHCs, appear to span a broad redox range (~200 mV), supporting the hypothesis that MHCs confer substantial redox flexibility. This flexibility may be a principle reason for the abundance of MHCs expressed by microorganisms capable of extracellular electron transfer to minerals.

  15. Redox-sensitive micelles self-assembled from amphiphilic hyaluronic acid-deoxycholic acid conjugates for targeted intracellular delivery of paclitaxel.

    PubMed

    Li, Jing; Huo, Meirong; Wang, Jing; Zhou, Jianping; Mohammad, Jumah M; Zhang, Yinlong; Zhu, Qinnv; Waddad, Ayman Y; Zhang, Qiang

    2012-03-01

    A targeted intracellular delivery system of paclitaxel (PTX) was successfully developed based on redox-sensitive hyaluronic acid-deoxycholic acid (HA-ss-DOCA) conjugates. The conjugates self-assembled into nano-size micelles in aqueous media and exhibited excellent drug-loading capacities (34.1%) and entrapment efficiency (93.2%) for PTX. HA-ss-DOCA micelles were sufficiently stable at simulated normal physiologic condition but fast disassembled in the presence of 20 mm reducing agent, glutathione. In vitro drug release studies showed that the PTX-loaded HA-ss-DOCA micelles accomplished rapid drug release under reducing condition. Intracellular release of fluorescent probe nile red indicated that HA-ss-DOCA micelles provide an effective approach for rapid transport of cargo into the cytoplasm. Enhanced cytotoxicity of PTX-loaded HA-ss-DOCA micelles further confirmed that the sensitive micelles are more potent for intracellular drug delivery as compared to the insensitive control. Based on flow cytometry and confocal microscopic analyses, observations revealed that HA-ss-DOCA micelles were taken up to human breast adenocarcinoma cells (MDA-MB-231) via HA-receptor mediated endocytosis. In vivo investigation of micelles in tumor-bearing mice confirmed that HA-ss-DOCA micelles possessed much higher tumor targeting capacity than the insensitive control. These results suggest that redox-sensitive HA-ss-DOCA micelles hold great potential as targeted intracellular delivery carriers of lipophilic anticancer drugs.

  16. Feasibility of assessing health state by detecting redox state of human body based on Chinese medicine constitution.

    PubMed

    Li, Ling-Ru; Wang, Qi; Wang, Ji; Wang, Qian-Fei; Yang, Ling-Ling; Zheng, Lu-Yu; Zhang, Yan

    2016-08-01

    This article discussed the feasibility of assessing health state by detecting redox state of human body. Firstly, the balance of redox state is the basis of homeostasis, and the balance ability of redox can reflflect health state of human body. Secondly, the redox state of human body is a sensitive index of multiple risk factors of health such as age, external environment and psychological factors. It participates in the occurrence and development of multiple diseases involving metabolic diseases and nervous system diseases, and can serve as a cut-in point for treatment of these diseases. Detecting the redox state of high risk people is signifificantly important for early detection and treatment of disease. The blood plasma and urine could be selected to detect, which is convenient. It is pointed that the indexes not only involve oxidation product and antioxidant enzyme but also redox couple. Chinese medicine constitution reflflects the state of body itself and the ability of adapting to external environment, which is consistent with the connotation of health. It is found that there are nine basic types of constitution in Chinese population, which provides a theoretical basis of health preservation, preventive treatment of disease and personalized treatment. With the combination of redox state detection and the Chinese medicine constitution theory, the heath state can be systemically assessed by conducting large-scale epidemiological survey with classifified detection on redox state of human body.

  17. Redox and pH dual responsive poly(amidoamine) dendrimer-poly(ethylene glycol) conjugates for intracellular delivery of doxorubicin.

    PubMed

    Hu, Wen; Qiu, Lipeng; Cheng, Liang; Hu, Qing; Liu, Yang; Hu, Ziyang; Chen, Dawei; Cheng, Lifang

    2016-05-01

    To solve the contradiction between long circulation time and effective intracellular drug release, redox and pH-responsive drug delivery system was developed by incorporated redox-sensitive disulfide linkage between poly(amidoamine) dendrimers (PAMAM) and poly(ethylene glycol) (PEG). Doxorubicin (DOX) was loaded into the hydrophobic core of the conjugates to prepare PAMAM-SS-PEG/DOX complexes (PSSP/DOX). In vitro release studies suggested that DOX release from PSSP/DOX complexes followed an redox and acid-triggered manner and increased with increasing PEGylation degree. In vitro cytotoxicity of PSSP/DOX complexes against B16 tumor cells increased with, while cellular uptake decreased with increasing PEGylation degree. Further, intracellular DOX release observation and measurement indicate that the intracellular DOX release played a critical role for the cytotoxicity of DOX-loaded PSSP conjugates. In addition, cellular entry mechanism of the PSSP/DOX study demonstrated that both clathrin- and caveolae-mediated endocytosis were the primary pathways for cellular entry of PSSP/DOX. Finally, in vivo study of PSSP/DOX complexes in B16 tumor-bearing mice indicate that PSSP/DOX could significantly improve antitumor efficiency and present a good safety. The redox and pH-responsive drug delivery system has been demonstrated to be a promising candidate for solid tumor therapy. In previous research, pH-sensitive diblock polymer of poly(ethylene glycol)-poly(2,4,6-trimethoxybenzylidene-pentaerythritol carbonate) (PEG-PTMBPEC) was synthesized to facilitate the intracellular anticancer drug release. However, the nanoparticles based on PEG-PTMBPEC get into the tumor cells just relying on the EPR-mediated passive targeting resulting in the low drug accumulation. Therefore, cRGD peptide modified PEG-PTMBPEC polymeric micelles were developed for specific targeted delivery of doxorubicin (DOX) to neovascular cells and tumor cells simultaneously. The precise intracellular target site

  18. 20S proteasome activity is modified via S-glutathionylation based on intracellular redox status of the yeast Saccharomyces cerevisiae: implications for the degradation of oxidized proteins.

    PubMed

    Demasi, Marilene; Hand, Adrian; Ohara, Erina; Oliveira, Cristiano L P; Bicev, Renata N; Bertoncini, Clelia A; Netto, Luis E S

    2014-09-01

    Protein S-glutathionylation is a post-translational modification that controls many cellular pathways. Recently, we demonstrated that the α5-subunit of the 20S proteasome is S-glutathionylated in yeast cells grown to the stationary phase in rich medium containing glucose, stimulating 20S core gate opening and increasing the degradation of oxidized proteins. In the present study, we evaluated the correlation between proteasomal S-glutathionylation and the intracellular redox status. The redox status was controlled by growing yeast cells in distinct carbon sources which induced respiratory (glycerol/ethanol) or fermentative (glucose) metabolism. Cells grown under glycerol/ethanol displayed higher reductive power when compared to cells grown under glucose. When purified from cells grown in glucose, 20S proteasome α5-subunit exhibited an intense anti-glutathione labeling. A higher frequency of the open catalytic chamber gate was observed in the S-glutathionylated preparations as demonstrated by transmission electron microscopy. Therefore, cells that had been grown in glucose displayed an increased ability to degrade oxidized proteins. The results of the present study suggest that 20S proteasomal S-glutathionylation is a relevant adaptive response to oxidative stress that is capable to sense the intracellular redox environment, leading to the removal of oxidized proteins via a process that is not dependent upon ubiquitylation and ATP consumption. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. A Novel Redox State Heme a Marker in Cytochrome c Oxidase Revealed by Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Piccoli, C.; Perna, G.; Scrima, R.; Cela, O.; Rinaldi, R.; Boffoli, D.; Capozzi, V.; Capitanio, N.

    2005-01-01

    This study was aimed to characterize by Raman spectroscopy (excitation line 633 nm) different redox states of the mitochondrial cytochrome c oxidase. The results obtained from a systematic analysis carried out on the mitochondrial enzyme prepared under redox conditions, differently affecting the valence state of the metal prosthetic groups, and a comparison with homologous bacterial heme-copper oxidases, cytochrome c and pyridine hemo-chrome extract revealed a novel redox state marker specifically linked to the redox transition of heme a, peaking at 1645 cm-1, and tentatively assigned to the C=C and/or C=N streching mode of the imidazole ring of a proxymal histidine ligand. The possible involvment of this redox-linked conformational change in the catalytic activity of cytochrome oxidase is discussed.

  20. Redox state and O2*- production in neutrophils of Crohn's disease patients.

    PubMed

    Biagioni, Chiara; Favilli, Fabio; Catarzi, Serena; Marcucci, Tommaso; Fazi, Marilena; Tonelli, Francesco; Vincenzini, Maria T; Iantomasi, Teresa

    2006-02-01

    The aim of this in vitro study was to evaluate the intracellular redox state and respiratory burst (RB) in neutrophils of patients with Crohn's disease (CD). The intracellular redox state and RB in neutrophils was assessed by the superoxide anion (O2*-) production induced in these cells after stimulation by various factors related to the molecular mechanisms that, if altered, may be responsible for an abnormal immune response. This can, in part, cause the onset of inflammation and tissue damage seen in CD. This study demonstrated a decreased glutathione/glutathione disulfide (GSH/GSSG) ratio index of an increased oxidative state in CD patient neutrophils. Moreover, our findings showed a decrease in tumor necrosis factor (TNF-alpha)- or phorbol 12-myristate 13-acetate (PMA)-induced O2*- production in CD patient neutrophils adherent to fibronectin as compared with controls. A decreased adhesion was also demonstrated. For this reason, the involvement of altered mechanisms of protein kinase C (PKC) and beta-integrin activation in CD patient neutrophils is suggested. These data also showed that the harmful effects of TNF-alpha cannot be caused by excessive reactive oxygen species (ROS) production induced by neutrophils. Decreased cell viability after a prolonged time of adhesion (20 hrs) was also measured in CD patient neutrophils. The findings of this study demonstrate, for the first time, that granulocyte-macrophage colony-stimulating factor (GM-CSF), a compound recently used in CD therapy, is able to activate the RB for a prolonged time both in control and CD patient neutrophils. Increased viability of CD patient neutrophils caused by GM-CSF stimulation was also observed. In conclusion, our results indicate that decreased O2*- production and adhesion, caused, in part, by an anomalous response to TNF-alpha, together with low GSH level and low cell viability, may be responsible for the defective neutrophil function found in CD patients. This can contribute to the

  1. Extracellular redox state: refining the definition of oxidative stress in aging.

    PubMed

    Jones, Dean P

    2006-01-01

    Oxidative stress in aging can result from an imbalance of prooxidants and antioxidants with excessive, destructive free radical chemistry. Thiol systems are important in the control of these processes, both by protecting against damage and serving in redox signaling mechanisms to sense danger and repair the damage. Studies by a number of research groups in collaboration with the Emory Clinical Biomarkers Laboratory show that the redox state of the central tissue antioxidant, glutathione (GSH), can be measured in human plasma and provides a quantitative systemic indicator of oxidative stress. Plasma GSH/GSSG redox in humans becomes oxidized with age, in response to chemotherapy, as a consequence of cigarette smoking, and in association with common age-related diseases (e.g., type 2 diabetes, cardiovascular disease). However, the GSH/GSSG redox is not equilibrated with the larger plasma cysteine/cystine (Cys/CySS) pool, and the Cys/CySS redox varies with age in a pattern that is distinct from that of GSH/GSSG redox. Furthermore, in vitro studies show that variation in Cys/CySS redox over the range found in vivo affects signaling pathways, which control cell proliferation and oxidant-induced apoptosis. The results point to the conclusion that free radical scavenging antioxidants are of increased importance when thiol/disulfide redox states are oxidized. Because thiol/disulfide redox states, per se, function in redox signaling and control as well as antioxidant protection, GSH/GSSG and Cys/CySS redox states may provide central parameters to link environmental influences and progression of changes associated with aging.

  2. Exogenous antioxidants—Double-edged swords in cellular redox state

    PubMed Central

    Bohn, Torsten

    2010-01-01

    The balance between oxidation and antioxidation is believed to be critical in maintaining healthy biological systems. Under physiological conditions, the human antioxidative defense system including e.g., superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione (GSH) and others, allows the elimination of excess reactive oxygen species (ROS) including, among others superoxide anions (O2.-), hydroxyl radicals (OH.), alkoxyl radicals (RO.) and peroxyradicals (ROO.). However, our endogenous antioxidant defense systems are incomplete without exogenous originating reducing compounds such as vitamin C, vitamin E, carotenoids and polyphenols, playing an essential role in many antioxidant mechanisms in living organisms. Therefore, there is continuous demand for exogenous antioxidants in order to prevent oxidative stress, representing a disequilibrium redox state in favor of oxidation. However, high doses of isolated compounds may be toxic, owing to prooxidative effects at high concentrations or their potential to react with beneficial concentrations of ROS normally present at physiological conditions that are required for optimal cellular functioning. This review aims to examine the double-edged effects of dietary originating antioxidants with a focus on the most abundant compounds, especially polyphenols, vitamin C, vitamin E and carotenoids. Different approaches to enrich our body with exogenous antioxidants such as via synthetic antioxidants, diets rich in fruits and vegetables and taking supplements will be reviewed and experimental and epidemiological evidences discussed, highlighting that antioxidants at physiological doses are generally safe, exhibiting interesting health beneficial effects. PMID:20972369

  3. Redox state of plutonium in irradiated mixed oxide fuels

    NASA Astrophysics Data System (ADS)

    Degueldre, C.; Pin, S.; Poonoosamy, J.; Kulik, D. A.

    2014-03-01

    Nowadays, MOX fuels are used in about 20 nuclear power plants around the world. After irradiation, plutonium co-exists with uranium oxide. Due to the redox sensitive nature of UO2 other plutonium oxides than PuO2 potentially present in the fuel may interact with the matrix. The aim of this study is to determine which plutonium species are present in heterogeneous and homogeneous MOX. The results provided by X-ray Absorption Near Edge Spectroscopy (XANES) for non-irradiated as well as irradiated (center and periphery) homogeneous MOX fuel were published earlier and are completed by Extended X-ray Fine Structure (EXAFS) analysis in this work. The EXAFS signals have been extracted using the ATHENA code and the analyses were carried using EXCURE98 as performed earlier for an analogous element. EXAFS shows that plutonium redox state remains tetravalent in the solid solution and that the minor fraction of trivalent Pu must be below 10%. Independently, the study of homogeneous MOX was also approached by thermodynamics of solid solution of (U,Pu)O2. Such solid solutions were modeled using the Gibbs Energy Minimisation (GEM)-Selektor code (developed at LES, NES, PSI) supported by the literature data on such solid solutions. A comparative study was performed showing which plutonium oxides in their respective mole fractions are more likely to occur in (U,Pu)O2. In the modeling, these oxides were set as ideal and non-ideal solid solutions, as well as separate pure phases. Pu exists mainly as PuO2 in the case of separate phases, but can exist under its reduced forms, PuO1.61 and PuO1.5 in minor fraction i.e. ~15% in ideal solid solution (unlikely) and ~10% in non-ideal solid solution (likely) and at temperature around 1300 K. This combined thermodynamic and EXAFS studies confirm independently the results obtained so far by Pu XANES for the same MOX samples.

  4. Arteriovenous oscillations of the redox potential: Is the redox state influencing blood flow?

    PubMed

    Poznanski, Jaroslaw; Szczesny, Pawel; Pawlinski, Bartosz; Mazurek, Tomasz; Zielenkiewicz, Piotr; Gajewski, Zdzislaw; Paczek, Leszek

    2017-09-01

    Studies on the regulation of human blood flow revealed several modes of oscillations with frequencies ranging from 0.005 to 1 Hz. Several mechanisms were proposed that might influence these oscillations, such as the activity of vascular endothelium, the neurogenic activity of vessel wall, the intrinsic activity of vascular smooth muscle, respiration, and heartbeat. These studies relied typically on non-invasive techniques, for example, laser Doppler flowmetry. Oscillations of biochemical markers were rarely coupled to blood flow. The redox potential difference between the artery and the vein was measured by platinum electrodes placed in the parallel homonymous femoral artery and the femoral vein of ventilated anesthetized pigs. Continuous measurement at 5 Hz sampling rate using a digital nanovoltmeter revealed fluctuating signals with three basic modes of oscillations: ∼ 1, ∼ 0.1 and ∼ 0.01 Hz. These signals clearly overlap with reported modes of oscillations in blood flow, suggesting coupling of the redox potential and blood flow. The amplitude of the oscillations associated with heart action was significantly smaller than for the other two modes, despite the fact that heart action has the greatest influence on blood flow. This finding suggests that redox potential in blood might be not a derivative but either a mediator or an effector of the blood flow control system.

  5. Mantle redox evolution and the oxidation state of the Archean atmosphere

    NASA Technical Reports Server (NTRS)

    Kasting, J. F.; Eggler, D. H.; Raeburn, S. P.

    1993-01-01

    Current models predict that the early atmosphere consisted mostly of CO2, N2, and H2O, along with traces of H2 and CO. Such models are based on the assumption that the redox state of the upper mantle has not changed, so that volcanic gas composition has remained approximately constant with time. We argue here that this assumption is probably incorrect: the upper mantle was originally more reduced than today, although not as reduced as the metal arrest level, and has become progressively more oxidized as a consequence of the release of reduced volcanic gases and the subduction of hydrated, oxidized seafloor. Data on the redox state of sulfide and chromite inclusions in diamonds imply that the process of mantle oxidation was slow, so that reduced conditions could have prevailed for as much as half of the earth's history. To be sure, other oxybarometers of ancient rocks give different results, so the question of when the mantle redox state has changed remains unresolved. Mantle redox evolution is intimately linked to the oxidation state of the primitive atmosphere: A reduced Archean atmosphere would have had a high hydrogen escape rate and should correspond to a changing mantle redox state; an oxidized Archean atmosphere should be associated with a constant mantle redox state. The converses of these statements are also true. Finally, our theory of mantle redox evolution may explain why the Archean atmosphere remained oxygen-deficient until approximately 2.0 billion years ago (Ga) despite a probable early origin for photosynthesis.

  6. Redox Conditions in Selected Principal Aquifers of the United States

    USGS Publications Warehouse

    McMahon, P.B.; Cowdery, T.K.; Chapelle, F.H.; Jurgens, B.C.

    2009-01-01

    Reduction/oxidation (redox) processes affect the quality of groundwater in all aquifer systems. Redox processes can alternately mobilize or immobilize potentially toxic metals associated with naturally occurring aquifer materials, contribute to the degradation or preservation of anthropogenic contami-nants, and generate undesirable byproducts, such as dissolved manganese (Mn2+), ferrous iron (Fe2+), hydrogen sulfide (H2S), and methane (CH4). Determining the kinds of redox processes that occur in an aquifer system, documenting their spatial distribution, and understanding how they affect concentrations of natural or anthropogenic contaminants are central to assessing and predicting the chemical quality of groundwater. This Fact Sheet extends the analysis of U.S. Geological Survey authors to additional principal aquifer systems by applying a framework developed by the USGS to a larger set of water-quality data from the USGS national water databases. For a detailed explanation, see the 'Introduction' in the Fact Sheet.

  7. Prediction of intracellular metabolic states from extracellular metabolomic data.

    PubMed

    Aurich, Maike K; Paglia, Giuseppe; Rolfsson, Óttar; Hrafnsdóttir, Sigrún; Magnúsdóttir, Manuela; Stefaniak, Magdalena M; Palsson, Bernhard Ø; Fleming, Ronan M T; Thiele, Ines

    Metabolic models can provide a mechanistic framework to analyze information-rich omics data sets, and are increasingly being used to investigate metabolic alternations in human diseases. An expression of the altered metabolic pathway utilization is the selection of metabolites consumed and released by cells. However, methods for the inference of intracellular metabolic states from extracellular measurements in the context of metabolic models remain underdeveloped compared to methods for other omics data. Herein, we describe a workflow for such an integrative analysis emphasizing on extracellular metabolomics data. We demonstrate, using the lymphoblastic leukemia cell lines Molt-4 and CCRF-CEM, how our methods can reveal differences in cell metabolism. Our models explain metabolite uptake and secretion by predicting a more glycolytic phenotype for the CCRF-CEM model and a more oxidative phenotype for the Molt-4 model, which was supported by our experimental data. Gene expression analysis revealed altered expression of gene products at key regulatory steps in those central metabolic pathways, and literature query emphasized the role of these genes in cancer metabolism. Moreover, in silico gene knock-outs identified unique control points for each cell line model, e.g., phosphoglycerate dehydrogenase for the Molt-4 model. Thus, our workflow is well-suited to the characterization of cellular metabolic traits based on extracellular metabolomic data, and it allows the integration of multiple omics data sets into a cohesive picture based on a defined model context.

  8. Propelled Transnuclear Gene Transport Achieved through Intracellularly Redox-Responsive and Acidity-Accelerative Decomposition of Supramolecular Florescence-Quenchable Vectors.

    PubMed

    Zhu, Jing-Yi; Wan, Shuang-Shuang; Zheng, Di-Wei; Lei, Qi; Zhuo, Ren-Xi; Feng, Jun; Zhang, Xian-Zheng

    2017-01-11

    Intracellularly biotriggered decomposition of gene vectors is generally thought to benefit transfection. However, the bioresponsiveness is far from satisfactory, and the exact role of biodecomposition in the transfection process remains unclear to date. To overcome the challenges, highly rapid bioresponse of vectors has to be achieved so as to greatly amplify the intracellular deviation compared with the noncontrolled pattern. To this end, a supramolecular polyrotaxane has been elaborately designed by integrating reversible dynamics of supramolecular assembly and chemically labile bonds, in order to effectively propel intracellular decomposition. Inside tumor cells, the redox-responsive bulk dissociation of the supramolecular vector readily took place and was further accelerated by the lysosomal-acidity-triggered terminal decomposition. Both the in vitro and in vivo experiments have demonstrated that this supramolecule could mediate considerably more rapid gene accumulation in nuclei than the nonresponsive controls including PEI25K, the gold standard of nonviral vectors. Along with the structural decomposition, the supramolecule simultaneously underwent the transition of fluorescence quenching, favoring the evaluation over the bioresponsiveness inside cells. Based on the resulting data, it is suggested that the biotriggered volume expansion of supramolecule/DNA complexes may be the major factor accounting for that dramatically accelerated transnuclear gene transport during cellular mitosis, thus affecting the transfection. This study offers an understanding of the intracellular gene transport from a new viewpoint.

  9. Redox state of low-molecular-weight thiols and disulphides during somatic embryogenesis of salt-treated suspension cultures of Dactylis glomerata L.

    PubMed

    Zagorchev, Lyuben; Seal, Charlotte E; Kranner, Ilse; Odjakova, Mariela

    2012-05-01

    The tripeptide antioxidant γ-L-glutamyl-L-cysteinyl-glycine, or glutathione (GSH), serves a central role in ROS scavenging and oxidative signalling. Here, GSH, glutathione disulphide (GSSG), and other low-molecular-weight (LMW) thiols and their corresponding disulphides were studied in embryogenic suspension cultures of Dactylis glomerata L. subjected to moderate (0.085 M NaCl) or severe (0.17 M NaCl) salt stress. Total glutathione (GSH + GSSG) concentrations and redox state were associated with growth and development in control cultures and in moderately salt-stressed cultures and were affected by severe salt stress. The redox state of the cystine (CySS)/2 cysteine (Cys) redox couple was also affected by developmental stage and salt stress. The glutathione half-cell reduction potential (E(GSSG/2 GSH)) increased with the duration of culturing and peaked when somatic embryos were formed, as did the half-cell reduction potential of the CySS/2 Cys redox couple (E(CySS/2 Cys)). The most noticeable relationship between cellular redox state and developmental state was found when all LMW thiols and disulphides present were mathematically combined into a 'thiol-disulphide redox environment' (E(thiol-disulphide)), whereby reducing conditions accompanied proliferation, resulting in the formation of pro-embryogenic masses (PEMs), and oxidizing conditions accompanied differentiation, resulting in the formation of somatic embryos. The comparatively high contribution of E(CySS/2 Cys) to E(thiol-disulphide) in cultures exposed to severe salt stress suggests that Cys and CySS may be important intracellular redox regulators with a potential role in stress signalling.

  10. Redox state and energy metabolism during liver regeneration: alterations produced by acute ethanol administration.

    PubMed

    Gutiérrez-Salinas, J; Miranda-Garduño, L; Trejo-Izquierdo, E; Díaz-Muñoz, M; Vidrio, S; Morales-González, J A; Hernández-Muñoz, R

    1999-12-01

    Ethanol metabolism can induce modifications in liver metabolic pathways that are tightly regulated through the availability of cellular energy and through the redox state. Since partial hepatectomy (PH)-induced liver proliferation requires an oversupply of energy for enhanced syntheses of DNA and proteins, the present study was aimed at evaluating the effect of acute ethanol administration on the PH-induced changes in cellular redox and energy potentials. Ethanol (5 g/kg body weight) was administered to control rats and to two-thirds hepatectomized rats. Quantitation of the liver content of lactate, pyruvate, beta-hydroxybutyrate, acetoacetate, and adenine nucleotides led us to estimate the cytosolic and mitochondrial redox potentials and energy parameters. Specific activities in the liver of alcohol-metabolizing enzymes also were measured in these animals. Liver regeneration had no effect on cellular energy availability, but induced a more reduced cytosolic redox state accompanied by an oxidized mitochondrial redox state during the first 48 hr of treatment; the redox state normalized thereafter. Administration of ethanol did not modify energy parameters in PH rats, but this hepatotoxin readily blocked the PH-induced changes in the cellular redox state. In addition, proliferating liver promoted decreases in the activity of alcohol dehydrogenase (ADH) and of cytochrome P4502E1 (CYP2E1); ethanol treatment prevented the PH-induced diminution of ADH activity. In summary, our data suggest that ethanol could minimize the PH-promoted metabolic adjustments mediated by redox reactions, probably leading to an ineffective preparatory event that culminates in compensatory liver growth after PH in the rat.

  11. Redox-Based Regulation of Bacterial Development and Behavior.

    PubMed

    Sporer, Abigail J; Kahl, Lisa J; Price-Whelan, Alexa; Dietrich, Lars E P

    2017-06-20

    Severe changes in the environmental redox potential, and resulting alterations in the oxidation states of intracellular metabolites and enzymes, have historically been considered negative stressors, requiring responses that are strictly defensive. However, recent work in diverse organisms has revealed that more subtle changes in the intracellular redox state can act as signals, eliciting responses with benefits beyond defense and detoxification. Changes in redox state have been shown to influence or trigger chromosome segregation, sporulation, aerotaxis, and social behaviors, including luminescence as well as biofilm establishment and dispersal. Connections between redox state and complex behavior allow bacteria to link developmental choices with metabolic state and coordinate appropriate responses. Promising future directions for this area of study include metabolomic analysis of species- and condition-dependent changes in metabolite oxidation states and elucidation of the mechanisms whereby the redox state influences circadian regulation.

  12. Noninvasive optical cytochrome c oxidase redox state measurements using diffuse optical spectroscopy

    NASA Astrophysics Data System (ADS)

    Lee, Jangwoen; Kim, Jae G.; Mahon, Sari B.; Mukai, David; Yoon, David; Boss, Gerry R.; Patterson, Steven E.; Rockwood, Gary; Isom, Gary; Brenner, Matthew

    2014-05-01

    A major need exists for methods to assess organ oxidative metabolic states in vivo. By contrasting the responses to cyanide (CN) poisoning versus hemorrhage in animal models, we demonstrate that diffuse optical spectroscopy (DOS) can detect cytochrome c oxidase (CcO) redox states. Intermittent decreases in inspired O2 from 100% to 21% were applied before, during, and after CN poisoning, hemorrhage, and resuscitation in rabbits. Continuous DOS measurements of total hemoglobin, oxyhemoglobin, deoxyhemoglobin, and oxidized and reduced CcO from muscle were obtained. Rabbit hemorrhage was accomplished with stepwise removal of blood, followed by blood resuscitation. CN treated rabbits received 0.166 mg/min NaCN infusion. During hemorrhage, CcO redox state became reduced concurrently with decreases in oxyhemoglobin, resulting from reduced tissue oxygen delivery and hypoxia. In contrast, during CN infusion, CcO redox state decreased while oxyhemoglobin concentration increased due to CN binding and reduction of CcO with resultant inhibition of the electron transport chain. Spectral absorption similarities between hemoglobin and CcO make noninvasive spectroscopic distinction of CcO redox states difficult. By contrasting physiological perturbations of CN poisoning versus hemorrhage, we demonstrate that DOS measured CcO redox state changes are decoupled from hemoglobin concentration measurement changes.

  13. Redox state dependence of axial ligand dynamics in Nitrosomonas europaea cytochrome c552.

    PubMed

    Kaur, Ravinder; Bren, Kara L

    2013-12-12

    Analysis of NMR spectra reveals that the heme axial Met ligand orientation and dynamics in Nitrosomonas europaea cytochrome c552 (Ne cyt c) are dependent on the heme redox state. In the oxidized state, the heme axial Met is fluxional, interconverting between two conformers related to each other by inversion through the Met δS atom. In the reduced state, there is no evidence of fluxionality, with the Met occupying one conformation similar to that seen in the homologous Pseudomonas aeruginosa cytochrome c551. Comparison of the observed and calculated pseudocontact shifts for oxidized Ne cyt c using the reduced protein structure as a reference structure reveals a redox-dependent change in the structure of the loop bearing the axial Met (loop 3). Analysis of nuclear Overhauser effects (NOEs) and existing structural data provides further support for the redox state dependence of the loop 3 structure. Implications for electron transfer function are discussed.

  14. Mitochondrial Thioredoxin System as a Modulator of Cyclophilin D Redox State

    NASA Astrophysics Data System (ADS)

    Folda, Alessandra; Citta, Anna; Scalcon, Valeria; Calì, Tito; Zonta, Francesco; Scutari, Guido; Bindoli, Alberto; Rigobello, Maria Pia

    2016-03-01

    The mitochondrial thioredoxin system (NADPH, thioredoxin reductase, thioredoxin) is a major redox regulator. Here we have investigated the redox correlation between this system and the mitochondrial enzyme cyclophilin D. The peptidyl prolyl cis-trans isomerase activity of cyclophilin D was stimulated by the thioredoxin system, while it was decreased by cyclosporin A and the thioredoxin reductase inhibitor auranofin. The redox state of cyclophilin D, thioredoxin 1 and 2 and peroxiredoxin 3 was measured in isolated rat heart mitochondria and in tumor cell lines (CEM-R and HeLa) by redox Western blot analysis upon inhibition of thioredoxin reductase with auranofin, arsenic trioxide, 1-chloro-2,4-dinitrobenzene or after treatment with hydrogen peroxide. A concomitant oxidation of thioredoxin, peroxiredoxin and cyclophilin D was observed, suggesting a redox communication between the thioredoxin system and cyclophilin. This correlation was further confirmed by i) co-immunoprecipitation assay of cyclophilin D with thioredoxin 2 and peroxiredoxin 3, ii) molecular modeling and iii) depleting thioredoxin reductase by siRNA. We conclude that the mitochondrial thioredoxin system controls the redox state of cyclophilin D which, in turn, may act as a regulator of several processes including ROS production and pro-apoptotic factors release.

  15. Mitochondrial Thioredoxin System as a Modulator of Cyclophilin D Redox State

    PubMed Central

    Folda, Alessandra; Citta, Anna; Scalcon, Valeria; Calì, Tito; Zonta, Francesco; Scutari, Guido; Bindoli, Alberto; Rigobello, Maria Pia

    2016-01-01

    The mitochondrial thioredoxin system (NADPH, thioredoxin reductase, thioredoxin) is a major redox regulator. Here we have investigated the redox correlation between this system and the mitochondrial enzyme cyclophilin D. The peptidyl prolyl cis-trans isomerase activity of cyclophilin D was stimulated by the thioredoxin system, while it was decreased by cyclosporin A and the thioredoxin reductase inhibitor auranofin. The redox state of cyclophilin D, thioredoxin 1 and 2 and peroxiredoxin 3 was measured in isolated rat heart mitochondria and in tumor cell lines (CEM-R and HeLa) by redox Western blot analysis upon inhibition of thioredoxin reductase with auranofin, arsenic trioxide, 1-chloro-2,4-dinitrobenzene or after treatment with hydrogen peroxide. A concomitant oxidation of thioredoxin, peroxiredoxin and cyclophilin D was observed, suggesting a redox communication between the thioredoxin system and cyclophilin. This correlation was further confirmed by i) co-immunoprecipitation assay of cyclophilin D with thioredoxin 2 and peroxiredoxin 3, ii) molecular modeling and iii) depleting thioredoxin reductase by siRNA. We conclude that the mitochondrial thioredoxin system controls the redox state of cyclophilin D which, in turn, may act as a regulator of several processes including ROS production and pro-apoptotic factors release. PMID:26975474

  16. Hypokinesia of myocardium of perfused rat heart at different oxygenation of myoglobin and redox state of cytochrome

    NASA Astrophysics Data System (ADS)

    Frank, Klaus H.; Zuendorf, J.; Tauschek, D.; Kessler, Manfred D.

    2002-06-01

    Questions about development of hypo-kinetic zones in myocardium of patients suffering from severe coronary heart disease are discussed controversially among heart surgeons. We established a model for isolated and hemoglobin free perfusion of rat heart in which sufficient flow was established within all capillaries and thus existence of ischemic capillaries could be excluded. A definite diagnosis of tissue anoxia is only possible by optical measurements of the oxidation and the reduction (redox state) of the cytochrome oxidase of intact myocytes. Therefore, we used an EMPHO for this kind of measurements. Intracellular oxygenation of myoglobin oxygenation (MbO2) and redox state of cytochrome aa3, b and c were recorded in the outer wall of working, hypo-kinetic and a-kinetic myocardium. As a result of our investigations we were able to prove that by lowering at the venous end of capillaries tissue pO2 and myoglobin oxygenation stepwise below 5 mmHg and 50% of saturation respectively, a continuous decrease of myocardial contractility could be achieved.

  17. Changes in intracellular and apoplastic peroxidase activity, ascorbate redox status, and root elongation induced by enhanced ascorbate content in Allium cepa L.

    PubMed

    Córdoba-Pedregosa, María del Carmen; Villalba, José Manuel; Córdoba, Francisco; González-Reyes, José Antonio

    2005-02-01

    Onions (Allium cepa L.) treated with external ascorbic acid or with the immediate precursor of its synthesis L-galactono-gamma-lactone show a stimulated elongation rate of the roots and an increase in the number of new radicles appearing at the bulb base. Treatment with both molecules resulted in an enhanced accumulation of ascorbate and dehydroascorbate along the root axis, but the distribution of these redox forms was not uniform along the root, as detected in intracellular (symplastic) and extracellular (apoplastic) compartments. Thus, those radicular zones metabolically more active, such as the meristem and the elongation zone, accumulated the highest amount of both redox forms of ascorbate. On the other hand, ascorbate and L-galactono-gamma-lactone also stimulated cytosolic glucose-6-phosphate dehydrogenase activity and inhibited peroxidase activity as deduced from in vivo and in vitro experiments. Differences were also found when comparing apoplastic and symplastic activities. These results are compatible with the idea of an ascorbate-mediated stimulation of root growth by inhibiting cell wall stiffening and increasing root metabolism.

  18. Six States Switching of Redox-Active Molecular Tweezers by Three Orthogonal Stimuli.

    PubMed

    Doistau, Benjamin; Benda, Lorien; Cantin, Jean-Louis; Chamoreau, Lise-Marie; Ruiz, Eliseo; Marvaud, Valérie; Hasenknopf, Bernold; Vives, Guillaume

    2017-07-12

    A six level molecular switch based on terpyridine(Ni-salphen)2 tweezers and addressable by three orthogonal stimuli (metal coordination, redox reaction, and guest binding) is reported. By a metal coordination stimulus, the tweezers can be mechanically switched from an open "W"-shaped conformation to a closed "U"-shaped form. Theses two states can each be reversibly oxidized by the redox stimulus and bind to a pyrazine guest resulting in four additional states. All six states are stable and accessible by the right combination of stimuli and were studied by NMR, XRD, EPR spectroscopy, and DFT calculations. The combination of the supramolecular concepts of mechanical motion and guest binding with the redox noninnocent and valence tautomerism properties of Ni-salphen complexes added two new dimensions to a mechanical switch.

  19. Quantum-dot/dopamine bioconjugates function as redox coupled assemblies for in vitro and intracellular pH sensing

    NASA Astrophysics Data System (ADS)

    Medintz, Igor L.; Stewart, Michael H.; Trammell, Scott A.; Susumu, Kimihiro; Delehanty, James B.; Mei, Bing C.; Melinger, Joseph S.; Blanco-Canosa, Juan B.; Dawson, Philip E.; Mattoussi, Hedi

    2010-08-01

    The use of semiconductor quantum dots (QDs) for bioimaging and sensing has progressively matured over the past decade. QDs are highly sensitive to charge-transfer processes, which can alter their optical properties. Here, we demonstrate that QD-dopamine-peptide bioconjugates can function as charge-transfer coupled pH sensors. Dopamine is normally characterized by two intrinsic redox properties: a Nernstian dependence of formal potential on pH and oxidation of hydroquinone to quinone by O2 at basic pH. We show that the latter quinone can function as an electron acceptor quenching QD photoluminescence in a manner that depends directly on pH. We characterize the pH-dependent QD quenching using both electrochemistry and spectroscopy. QD-dopamine conjugates were also used as pH sensors that measured changes in cytoplasmic pH as cells underwent drug-induced alkalosis. A detailed mechanism describing the QD quenching processes that is consistent with dopamine's inherent redox chemistry is presented.

  20. Intermittent fasting results in tissue-specific changes in bioenergetics and redox state.

    PubMed

    Chausse, Bruno; Vieira-Lara, Marcel A; Sanchez, Angélica B; Medeiros, Marisa H G; Kowaltowski, Alicia J

    2015-01-01

    Intermittent fasting (IF) is a dietary intervention often used as an alternative to caloric restriction (CR) and characterized by 24 hour cycles alternating ad libitum feeding and fasting. Although the consequences of CR are well studied, the effects of IF on redox status are not. Here, we address the effects of IF on redox state markers in different tissues in order to uncover how changes in feeding frequency alter redox balance in rats. IF rats displayed lower body mass due to decreased energy conversion efficiency. Livers in IF rats presented increased mitochondrial respiratory capacity and enhanced levels of protein carbonyls. Surprisingly, IF animals also presented an increase in oxidative damage in the brain that was not related to changes in mitochondrial bioenergetics. Conversely, IF promoted a substantial protection against oxidative damage in the heart. No difference in mitochondrial bioenergetics or redox homeostasis was observed in skeletal muscles of IF animals. Overall, IF affects redox balance in a tissue-specific manner, leading to redox imbalance in the liver and brain and protection against oxidative damage in the heart.

  1. Intermittent Fasting Results in Tissue-Specific Changes in Bioenergetics and Redox State

    PubMed Central

    Chausse, Bruno; Vieira-Lara, Marcel A.; Sanchez, Angélica B.; Medeiros, Marisa H. G.; Kowaltowski, Alicia J.

    2015-01-01

    Intermittent fasting (IF) is a dietary intervention often used as an alternative to caloric restriction (CR) and characterized by 24 hour cycles alternating ad libitum feeding and fasting. Although the consequences of CR are well studied, the effects of IF on redox status are not. Here, we address the effects of IF on redox state markers in different tissues in order to uncover how changes in feeding frequency alter redox balance in rats. IF rats displayed lower body mass due to decreased energy conversion efficiency. Livers in IF rats presented increased mitochondrial respiratory capacity and enhanced levels of protein carbonyls. Surprisingly, IF animals also presented an increase in oxidative damage in the brain that was not related to changes in mitochondrial bioenergetics. Conversely, IF promoted a substantial protection against oxidative damage in the heart. No difference in mitochondrial bioenergetics or redox homeostasis was observed in skeletal muscles of IF animals. Overall, IF affects redox balance in a tissue-specific manner, leading to redox imbalance in the liver and brain and protection against oxidative damage in the heart. PMID:25749501

  2. Assessment of Cellular Redox State Using NAD(P)H Fluorescence Intensity and Lifetime

    PubMed Central

    Blacker, Thomas S.; Berecz, Tunde; Duchen, Michael R.; Szabadkai, Gyorgy

    2017-01-01

    NADH and NADPH are redox cofactors, primarily involved in catabolic and anabolic metabolic processes respectively. In addition, NADPH plays an important role in cellular antioxidant defence. In live cells and tissues, the intensity of their spectrally-identical autofluorescence, termed NAD(P)H, can be used to probe the mitochondrial redox state, while their distinct enzyme-binding characteristics can be used to separate their relative contributions to the total NAD(P)H intensity using fluorescence lifetime imaging microscopy (FLIM). These protocols allow differences in metabolism to be detected between cell types and altered physiological and pathological states. PMID:28286806

  3. beta-sitosterol decreases irradiation-induced thymocyte early damage by regulation of the intracellular redox balance and maintenance of mitochondrial membrane stability.

    PubMed

    Li, Chun Rong; Zhou, Zhe; Lin, Ru Xin; Zhu, Dan; Sun, Yu Ning; Tian, Lin Lin; Li, Lu; Gao, Yue; Wang, Sheng Qi

    2007-10-15

    Both radiation injury and oxidation toxicity occur when cells are exposed to ion irradiation (IR), ultimately leading to apoptosis. This study was designed to determine the effect of beta-sitosterol (BSS) on early cellular damage in irradiated thymocytes and a possible mechanism of effect on irradiation-mediated activation of the apoptotic pathways. Thymocytes were irradiated (6 Gy) with or without BSS. Cell apoptosis and apoptosis-related proteins were evaluated. BSS decreased irradiation-induced cell death and nuclear DNA strand breaks while attenuating intracellular reactive oxygen species (ROS) and increasing the activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). BSS decreased the release of cytochrome c from mitochondria to the cytosol and the mitochondrio-nuclear translocation of apoptosis-inducing factor (AIF). Furthermore, BSS partially inhibited the radiation-induced increase of cleaved caspase 3 and cleaved PARP, and attenuated the activation of JNK and AP-1. In addition, evidence suggests that ROS generated by irradiation are involved in this course of cell damage. The results indicate that BSS confers a radioprotective effect on thymocytes by regulation of the intracellular redox balance which is carried out via the scavenging of ROS and maintenance of mitochondrial membrane stability.

  4. Crosstalk of Signaling and Metabolism Mediated by the NAD(+)/NADH Redox State in Brain Cells.

    PubMed

    Winkler, Ulrike; Hirrlinger, Johannes

    2015-12-01

    The energy metabolism of the brain has to be precisely adjusted to activity to cope with the organ's energy demand, implying that signaling regulates metabolism and metabolic states feedback to signaling. The NAD(+)/NADH redox state constitutes a metabolic node well suited for integration of metabolic and signaling events. It is affected by flux through metabolic pathways within a cell, but also by the metabolic state of neighboring cells, for example by lactate transferred between cells. Furthermore, signaling events both in neurons and astrocytes have been reported to change the NAD(+)/NADH redox state. Vice versa, a number of signaling events like astroglial Ca(2+) signals, neuronal NMDA-receptors as well as the activity of transcription factors are modulated by the NAD(+)/NADH redox state. In this short review, this bidirectional interdependence of signaling and metabolism involving the NAD(+)/NADH redox state as well as its potential relevance for the physiology of the brain and the whole organism in respect to blood glucose regulation and body weight control are discussed.

  5. Iron isotope constraints on the Archean and Paleoproterozoic ocean redox state.

    PubMed

    Rouxel, Olivier J; Bekker, Andrey; Edwards, Katrina J

    2005-02-18

    The response of the ocean redox state to the rise of atmospheric oxygen about 2.3 billion years ago (Ga) is a matter of controversy. Here we provide iron isotope evidence that the change in the ocean iron cycle occurred at the same time as the change in the atmospheric redox state. Variable and negative iron isotope values in pyrites older than about 2.3 Ga suggest that an iron-rich global ocean was strongly affected by the deposition of iron oxides. Between 2.3 and 1.8 Ga, positive iron isotope values of pyrite likely reflect an increase in the precipitation of iron sulfides relative to iron oxides in a redox stratified ocean.

  6. Redox states of Desulfovibrio vulgaris DsrC, a key protein in dissimilatory sulfite reduction.

    PubMed

    Venceslau, Sofia S; Cort, John R; Baker, Erin S; Chu, Rosalie K; Robinson, Errol W; Dahl, Christiane; Saraiva, Lígia M; Pereira, Inês A C

    2013-11-29

    Dissimilatory reduction of sulfite is carried out by the siroheme enzyme DsrAB, with the involvement of the protein DsrC, which has two conserved redox-active cysteines. DsrC was initially believed to be a third subunit of DsrAB. Here, we report a study of the distribution of DsrC in cell extracts to show that, in the model sulfate reducer Desulfovibrio vulgaris, the majority of DsrC is not associated with DsrAB and is thus free to interact with other proteins. In addition, we developed a cysteine-labelling gel-shift assay to monitor the DsrC redox state and behaviour, and procedures to produce the different redox forms. The oxidized state of DsrC with an intramolecular disulfide bond, which is proposed to be a key metabolic intermediate, could be successfully produced for the first time by treatment with arginine.

  7. Biochemical methods for monitoring protein thiol redox states in biological systems

    PubMed Central

    Rudyk, Olena; Eaton, Philip

    2014-01-01

    Oxidative post-translational modifications of proteins resulting from events that increase cellular oxidant levels play important roles in physiological and pathophysiological processes. Evaluation of alterations to protein redox states is increasingly common place because of methodological advances that have enabled detection, quantification and identification of such changes in cells and tissues. This mini-review provides a synopsis of biochemical methods that can be utilized to monitor the array of different oxidative and electrophilic modifications that can occur to protein thiols and can be important in the regulatory or maladaptive impact oxidants can have on biological systems. Several of the methods discussed are valuable for monitoring the redox state of established redox sensing proteins such as Keap1. PMID:25009782

  8. Redox biology of tuberculosis pathogenesis.

    PubMed

    Trivedi, Abhishek; Singh, Nisha; Bhat, Shabir Ahmed; Gupta, Pawan; Kumar, Ashwani

    2012-01-01

    Mycobacterium tuberculosis (Mtb) is one of the most successful human pathogens. Mtb is persistently exposed to numerous oxidoreductive stresses during its pathogenic cycle of infection and transmission. The distinctive ability of Mtb, not only to survive the redox stress manifested by the host but also to use it for synchronizing the metabolic pathways and expression of virulence factors, is central to its success as a pathogen. This review describes the paradigmatic redox and hypoxia sensors employed by Mtb to continuously monitor variations in the intracellular redox state and the surrounding microenvironment. Two component proteins, namely, DosS and DosT, are employed by Mtb to sense changes in oxygen, nitric oxide, and carbon monoxide levels, while WhiB3 and anti-sigma factor RsrA are used to monitor changes in intracellular redox state. Using these and other unidentified redox sensors, Mtb orchestrates its metabolic pathways to survive in nutrient-deficient, acidic, oxidative, nitrosative, and hypoxic environments inside granulomas or infectious lesions. A number of these metabolic pathways are unique to mycobacteria and thus represent potential drug targets. In addition, Mtb employs versatile machinery of the mycothiol and thioredoxin systems to ensure a reductive intracellular environment for optimal functioning of its proteins even upon exposure to oxidative stress. Mtb also utilizes a battery of protective enzymes, such as superoxide dismutase (SOD), catalase (KatG), alkyl hydroperoxidase (AhpC), and peroxiredoxins, to neutralize the redox stress generated by the host immune system. This chapter reviews the current understanding of mechanisms employed by Mtb to sense and neutralize redox stress and their importance in TB pathogenesis and drug development. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. Cellular redox state and endothelial dysfunction in mildly hyperhomocysteinemic cystathionine beta-synthase-deficient mice.

    PubMed

    Weiss, Norbert; Heydrick, Stanley; Zhang, Ying-Yi; Bierl, Charlene; Cap, André; Loscalzo, Joseph

    2002-01-01

    Previous in vitro experiments have shown that hyperhomocysteinemia leads to oxidative inactivation of nitric oxide, in part by inhibiting the expression of cellular glutathione peroxidase (GPx-1). To elucidate the role of intracellular redox status on homocysteine-induced endothelial dysfunction and oxidant stress, heterozygous cystathionine beta-synthase-deficient (CBS(-/+)) and wild-type (CBS(+/+)) mice were treated with the cysteine donor L-2-oxothiazolidine-4-carboxylic acid (OTC). CBS(-/+) mice had significantly lower GPx-1 activity compared with their CBS(+/+) littermates, and OTC treatment led to a modest increase in tissue GPx-1 activity and significant increases in total thiols and in reduced glutathione levels in both CBS(+/+) and CBS(-/+) mice. Superfusion of the mesentery with beta-methacholine or bradykinin produced dose-dependent vasodilation of mesenteric arterioles in CBS(+/+) mice and in CBS(+/+) mice treated with OTC. In contrast, mesenteric arterioles from CBS(-/+) mice manifested dose-dependent vasoconstriction in response to both agonists. OTC treatment of CBS(-/+) mice restored normal microvascular vasodilator reactivity to beta-methacholine and bradykinin. These findings demonstrate that mild hyperhomocysteinemia leads to endothelial dysfunction in association with decreased bioavailable nitric oxide. Increasing the cellular thiol and reduced glutathione pools and increasing GPx-1 activity restores endothelial function. These findings emphasize the importance of intracellular redox balance for nitric oxide bioactivity and endothelial function.

  10. Redox states of Desulfovibrio vulgaris DsrC, a key protein in dissimilatory sulfite reduction

    SciTech Connect

    Venceslau, Sofia S.; Cort, John R.; Baker, Erin S.; Chu, Rosalie K.; Robinson, Errol W.; Dahl, Christiane; Saraiva, Lígia M.; Pereira, Inês A.C.

    2013-11-29

    Highlights: •DsrC is known to interact with the dissimilatory sulfite reductase enzyme (DsrAB). •We show that, however, most cellular DsrC is not associated with DsrAB. •A gel-shift assay was developed that allows monitoring of the DsrC redox state. •The DsrC intramolecularly oxidized state could only be produced by arginine treatment. -- Abstract: Dissimilatory reduction of sulfite is carried out by the siroheme enzyme DsrAB, with the involvement of the protein DsrC, which has two conserved redox-active cysteines. DsrC was initially believed to be a third subunit of DsrAB. Here, we report a study of the distribution of DsrC in cell extracts to show that, in the model sulfate reducer Desulfovibrio vulgaris, the majority of DsrC is not associated with DsrAB and is thus free to interact with other proteins. In addition, we developed a cysteine-labelling gel-shift assay to monitor the DsrC redox state and behaviour, and procedures to produce the different redox forms. The oxidized state of DsrC with an intramolecular disulfide bond, which is proposed to be a key metabolic intermediate, could be successfully produced for the first time by treatment with arginine.

  11. Fluorescence spectroscopy and cryoimaging of rat lung tissue mitochondrial redox state

    NASA Astrophysics Data System (ADS)

    Sepehr, R.; Audi, S.; Staniszewski, K.; Maleki, S.; Ranji, M.

    2011-07-01

    The objective of this study was to demonstrate the utility of optical cryoimaging and fluorometry to evaluate tissue redox state of the mitochondrial metabolic coenzymes NADH (Nicotinamide Adenine Dinucleotide) and FAD (Flavin Adenine Dinucleotide) in intact rat lungs. The ratio (NADH/FAD), referred to as mitochondrial redox ratio (RR), is a measure of the lung tissue mitochondrial redox state. Isolated rat lungs were connected to a ventilation-perfused system. Surface NADH and FAD fluorescence signals were acquired before and after lung perfusion in the absence (control perfusate) or presence of potassium cyanide (KCN, complex IV inhibitor) to reduce the mitochondrial respiratory chain (state 5 respiration). Another group of lungs were perfused with control perfusate or KCN-containing perfusate as above, after which the lungs were deflated and frozen rapidly for subsequent 3D cryoimaging. Results demonstrate that lung treatment with KCN increased lung surface NADH signal by 22%, decreased FAD signal by 8%, and as result increased RR by 31% as compared to control perfusate (baseline) values. Cryoimaging results also show that KCN increased mean lung tissue NADH signal by 37%, decreased mean FAD signal by 4%, and increased mean RR by 47%. These results demonstrate the utility of these optical techniques to evaluate the effect of pulmonary oxidative stress on tissue mitochondrial redox state in intact lungs.

  12. Extrinsic periodic information interpolates between monostable and bistable states in intracellular calcium dynamics

    NASA Astrophysics Data System (ADS)

    Lin, Ling; Duan, Wei-Long

    2015-06-01

    Extrinsic periodic information including physiological cyclical and circadian replacement would affect inevitably a real cell, in this paper we investigate the effect of extrinsic periodic information on intracellular calcium dynamics by means of second-order algorithm for stochastic simulation colored noises. By simulating time evolutions and stationary probability distribution of intracellular Ca2+ concentrations, the results show: (i) intracellular calcium oscillation between cytosol and calcium store shows synchronous and anti-synchronous oscillation as intensity and frequency of extrinsic periodic information vary; (ii) extrinsic periodic information interpolates stability from bistable state → monostable state → bistable state → monostable state as frequency of extrinsic periodic information increases; (iii) extrinsic periodic information interpolates stability from monostable state → bistable state as intensity of extrinsic periodic information increases.

  13. Redox State of Cytochromes in Frozen Yeast Cells Probed by Resonance Raman Spectroscopy

    PubMed Central

    Okotrub, Konstantin A.; Surovtsev, Nikolay V.

    2015-01-01

    Cryopreservation is a well-established technique used for the long-term storage of biological materials whose biological activity is effectively stopped under low temperatures (suspended animation). Since most biological methods do not work in a low-temperature frozen environment, the mechanism and details of the depression of cellular activity in the frozen state remain largely uncharacterized. In this work, we propose, to our knowledge, a new approach to study the downregulation of the redox activity of cytochromes b and c in freezing yeast cells in a contactless, label-free manner. Our approach is based on cytochrome photobleaching effects observed in the resonance Raman spectra of live cells. Photoinduced and native redox reactions that contributed to the photobleaching rate were studied over a wide temperature range (from −173 to +25°C). We found that ice formation influences both the rate of cytochrome redox reactions and the balance between the reduced and oxidized cytochromes. We demonstrate that the temperature dependence of native redox reaction rates can be well described by the thermal activation law with an apparent energy of 32.5 kJ/mol, showing that the redox reaction rate is ∼1015 times slower at liquid nitrogen temperature than at room temperature. PMID:26636934

  14. Redox State of Cytochromes in Frozen Yeast Cells Probed by Resonance Raman Spectroscopy.

    PubMed

    Okotrub, Konstantin A; Surovtsev, Nikolay V

    2015-12-01

    Cryopreservation is a well-established technique used for the long-term storage of biological materials whose biological activity is effectively stopped under low temperatures (suspended animation). Since most biological methods do not work in a low-temperature frozen environment, the mechanism and details of the depression of cellular activity in the frozen state remain largely uncharacterized. In this work, we propose, to our knowledge, a new approach to study the downregulation of the redox activity of cytochromes b and c in freezing yeast cells in a contactless, label-free manner. Our approach is based on cytochrome photobleaching effects observed in the resonance Raman spectra of live cells. Photoinduced and native redox reactions that contributed to the photobleaching rate were studied over a wide temperature range (from -173 to +25 °C). We found that ice formation influences both the rate of cytochrome redox reactions and the balance between the reduced and oxidized cytochromes. We demonstrate that the temperature dependence of native redox reaction rates can be well described by the thermal activation law with an apparent energy of 32.5 kJ/mol, showing that the redox reaction rate is ∼10(15) times slower at liquid nitrogen temperature than at room temperature. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  15. Intracellular redox equilibrium is essential for the constitutive expression of AP-1 dependent genes in resting cells: studies on TGF-β1 regulation.

    PubMed

    González-Ramos, Marta; Mora, Inés; de Frutos, Sergio; Garesse, Rafael; Rodríguez-Puyol, Manuel; Olmos, Gemma; Rodríguez-Puyol, Diego

    2012-06-01

    The mechanisms involved in the continuous expression of constitutive genes are unclear. We hypothesize that steady state intracellular reactive oxygen species (ROS), which their levels are tightly maintained, could be regulating the expression of these constitutive genes in resting cells. We analyzed the regulation of an important constitutive gene, TGF-β1, after decreasing intracellular ROS concentration in human mesangial cells. Decreased intracellular hydrogen peroxide by catalase addition reduced TGF-β1 protein, mRNA expression and promoter activity. Furthermore, catalase decreased the basal activity of Activated Protein-1 (AP-1) that regulates TGF-β1 promoter activity. This effect disappeared when AP-1 binding site was removed. Similar results were observed with another protein containing AP-1 binding sites in its promoter, such as eNOS, but it was not the case in other constitutive genes without any AP-1 binding site, as COX1 or PKG1. The pharmacological inhibition of the different ROS synthesis sources by blocking NADPH oxidase, the mitochondrial respiratory chain or xanthine oxidase, or the use of human fibroblasts with genetically deficient mitochondrial activity, induced a similar, significant reduction of steady state ROS concentration as the one observed with catalase. Moreover, there was decreased TGF-β1 expression in all the cases excepting the xanthine oxidase blockade. These findings suggest a novel role for the steady state intracellular ROS concentration, where the compartmentalized, different systems involved in the intracellular ROS production, could be essential for the expression of constitutive AP1-dependent genes, as TGF-β1.

  16. Mapping solvation dynamics at the function site of flavodoxin in three redox states.

    PubMed

    Chang, Chih-Wei; He, Ting-Fang; Guo, Lijun; Stevens, Jeffrey A; Li, Tanping; Wang, Lijuan; Zhong, Dongping

    2010-09-15

    Flavoproteins are unique redox coenzymes, and the dynamic solvation at their function sites is critical to the understanding of their electron-transfer properties. Here, we report our complete characterization of the function-site solvation of holoflavodoxin in three redox states and of the binding-site solvation of apoflavodoxin. Using intrinsic flavin cofactor and tryptophan residue as the local optical probes with two site-specific mutations, we observed distinct ultrafast solvation dynamics at the function site in the three states and at the related recognition site of the cofactor, ranging from a few to hundreds of picoseconds. The initial ultrafast motion in 1-2.6 ps reflects the local water-network relaxation around the shallow, solvent-exposed function site. The second relaxation in 20-40 ps results from the coupled local water-protein fluctuation. The third dynamics in hundreds of picoseconds is from the intrinsic fluctuation of the loose loops flanking the cofactor at the function site. These solvation dynamics with different amplitudes well correlate with the redox states from the oxidized form, to the more rigid semiquinone and to the much looser hydroquinone. This observation of the redox control of local protein conformation plasticity and water network flexibility is significant, and such an intimate relationship is essential to the biological function of interprotein electron transfer.

  17. Disrupted intracellular redox balance of the diplomonad fish parasite Spironucleus vortens by 5-nitroimidazoles and garlic-derived compounds.

    PubMed

    Williams, C F; Lloyd, D; Kolarich, D; Alagesan, K; Duchêne, M; Cable, J; Williams, D; Leitsch, D

    2012-11-23

    The 5-nitroimidazole, metronidazole, has traditionally been employed in veterinary medicine to treat a range of infections including the diplomonad fish parasite Spironucleus. This study aims to determine the mode of action of metronidazole on Spironucleus vortens, including the specific mechanism of activation of the pro-drug and subsequent cellular targets of the drug metabolites. Due to the ban on use of metronidazole in the treatment of production animals in Europe and USA, garlic-derived compounds were also investigated as natural alternatives to metronidazole chemotherapy. Scanning electron microscopy (SEM) provided an overview of gross cellular damage caused by metronidazole and garlic derivatives. Proteomic analyses by 2D gel electrophoresis identified the proteins involved in specific covalent adduct formation with nitroimidazoles. Furthermore, thioredoxin reductase (TrxR) activity and non-protein thiol concentration were assayed in extracts of S. vortens before and after treatment with nitroimidazoles and garlic-derivatives. Metronidazole and garlic-derived compounds caused severe damage of trophozoites indicated by membrane blebbing and lysed cell debris. Analysis of the S. vortens proteome identified several proteins capable of specific nitroimidazole binding, including; uridine phosphorylase, enolase, protein disulphide isomerase, aminoacyl-histidine dipeptidase and malic enzyme. Of the compounds tested, metronidazole and the garlic-derived compound ajoene were the most effective at inhibiting TrxR activity and depleting non-protein thiols. These data suggest TrxR-mediated activation of nitroimidazoles, leading to depletion of non-protein thiols. Redox imbalance due to antioxidant failure is implicated as the mode of action of nitroimidazoles and garlic-derived compounds, ultimately leading to cell death. Possible synergy between garlic derivatives and metronidazole should be further investigated in vitro in order to determine their theoretical

  18. State of charge monitoring methods for vanadium redox flow battery control

    NASA Astrophysics Data System (ADS)

    Skyllas-Kazacos, Maria; Kazacos, Michael

    2011-10-01

    During operation of redox flow batteries, differential transfer of ions and electrolyte across the membrane and gassing side reactions during charging, can lead to an imbalance between the two half-cells that results in loss of capacity. This capacity loss can be corrected by either simple remixing of the two solutions, or by chemical or electrochemical rebalancing. In order to develop automated electrolyte management systems therefore, the state-of-charge of each half-cell electrolyte needs to be known. In this study, two state-of-charge monitoring methods are investigated for use in the vanadium redox flow battery. The first method utilizes conductivity measurements to independently measure the state-of-charge of each half-cell electrolyte. The second method is based on spectrophotometric principles and uses the different colours of the charged and discharged anolyte and catholyte to monitor system balance and state-of charge of each half-cell of the VRB during operation.

  19. Intracellular redox-responsive nanocarrier for plasmid delivery: in vitro characterization and in vivo studies in mice

    PubMed Central

    Zhang, Lifen; Zhang, Yushun; Chen, Zhenzhen; He, Yuling

    2016-01-01

    Although some modifications of polyethyleneimine (PEI) properties have been explored to balance the transfection efficiency and cytotoxicity, its successful plasmid delivery in vitro and in vivo to realize its true therapeutic potentials remains a major challenge, mainly due to intracellular trafficking barriers. Herein, we present a delivery nanocarrier Pluronic-PEI-SS by conjugating reducible disulfide-linked PEI (PEI-SS) to biocompatible Pluronic for enhanced DNA delivery and transfection efficiency in vitro and in vivo. Pluronic-PEI-SS strongly condensed plasmid DNA to low positively charged nanocomplexes, exhibited good stability against deoxyribonuclease I digestion, and tended to be easily degraded in the presence of reducing agent 1,4-dithiothreitol. The in vitro transfection of the complex Pluronic-PEI-SS/DNA into HeLa and 293T cells resulted in lower cytotoxicity as well as significantly higher cellular uptake, nucleus transfection, and gene expression than Pluronic-PEI (25 kDa), PEI-SS, and PEI 25 kDa given alone. Furthermore, the in vivo transfection study demonstrated that Pluronic-PEI-SS/DNA complexes induced a higher enrichment than the commercial PEI/DNA complex in the tumor, indicating their potential application as biocompatible vector in gene delivery. PMID:27785025

  20. Intracellular Redox State as Target for Anti-Influenza Therapy: Are Antioxidants Always Effective?

    PubMed Central

    Sgarbanti, Rossella; Amatore, Donatella; Celestino, Ignacio; Marcocci, Maria Elena; Fraternale, Alessandra; Ciriolo, Maria Rosa; Magnani, Mauro; Saladino, Raffaele; Garaci, Enrico; Palamara, Anna Teresa; Nencioni, Lucia

    2014-01-01

    Influenza virus infections represent a big issue for public health since effective treatments are still lacking. In particular, the emergence of strains resistant to drugs limits the effectiveness of anti-influenza agents. For this reason, many efforts have been dedicated to the identification of new therapeutic strategies aimed at targeting the virus-host cell interactions. Oxidative stress is a characteristic of some viral infections including influenza. Because antioxidants defend cells from damage caused by reactive oxygen species induced by different stimuli including pathogens, they represent interesting molecules to fight infectious diseases. However, most of the available studies have found that these would-be panaceas could actually exacerbate the diseases they claim to prevent, and have thus revealed "the dark side" of these molecules. This review article discusses the latest opportunities and drawbacks of the antioxidants used in anti-influenza therapy and new perspectives. PMID:25478883

  1. Cytochrome redox states and respiratory control in mouse and beef heart mitochondria at steady-state levels of hypoxia.

    PubMed

    Harrison, David K; Fasching, Mario; Fontana-Ayoub, Mona; Gnaiger, Erich

    2015-11-15

    Mitochondrial control of cellular redox states is a fundamental component of cell signaling in the coordination of core energy metabolism and homeostasis during normoxia and hypoxia. We investigated the relationship between cytochrome redox states and mitochondrial oxygen consumption at steady-state levels of hypoxia in mitochondria isolated from beef and mouse heart (BHImt, MHImt), comparing two species with different cardiac dynamics and local oxygen demands. A low-noise, rapid spectrophotometric system using visible light for the measurement of cytochrome redox states was combined with high-resolution respirometry. Monophasic hyperbolic relationships were observed between oxygen consumption, JO2, and oxygen partial pressure, Po2, within the range <1.1 kPa (8.3 mmHg; 13 μM). P50j (Po2 at 0.5·Jmax) was 0.015 ± 0.0004 and 0.021 ± 0.003 kPa (0.11 and 0.16 mmHg) for BHImt and MHImt, respectively. Maximum oxygen consumption, Jmax, was measured at saturating ADP levels (OXPHOS capacity) with Complex I-linked substrate supply. Redox states of cytochromes aa3 and c were biphasic hyperbolic functions of Po2. The relationship between cytochrome oxidation state and oxygen consumption revealed a separation of distinct phases from mild to severe and deep hypoxia. When cytochrome c oxidation increased from fully reduced to 45% oxidized at 0.1 Jmax, Po2 was as low as 0.002 kPa (0.02 μM), and trace amounts of oxygen are sufficient to partially oxidize the cytochromes. At higher Po2 under severe hypoxia, respiration increases steeply, whereas redox changes are small. Under mild hypoxia, the steep slope of oxidation of cytochrome c when flux remains more stable represents a cushioning mechanism that helps to maintain respiration high at the onset of hypoxia. Copyright © 2015 the American Physiological Society.

  2. Reactive oxygen species production and redox state in parthenogenetic and sperm-mediated bovine oocyte activation.

    PubMed

    Morado, S; Cetica, P; Beconi, M; Thompson, J G; Dalvit, G

    2013-05-01

    The knowledge concerning redox and reactive oxygen species (ROS)-mediated regulation of early embryo development is scarce and remains controversial. The aim of this work was to determine ROS production and redox state during early in vitro embryo development in sperm-mediated and parthenogenetic activation of bovine oocytes. Sperm-mediated oocyte activation was carried out in IVF-modified synthetic oviductal fluid (mSOF) with frozen-thawed semen. Parthenogenetic activation was performed in TALP plus ionomycin and then in IVF-mSOF with 6-dimethylaminopurine plus cytochalasin B. Embryos were cultured in IVF-mSOF. ROS and redox state were determined at each 2-h interval (7-24 h from activation) by 2',7'-dichlorodihydrofluorescein diacetate and RedoxSensor Red CC-1 fluorochromes respectively. ROS levels and redox state differed between activated and non-activated oocytes (P<0.05 by ANOVA). In sperm-activated oocytes, an increase was observed between 15 and 19 h (P<0.05). Conversely, in parthenogenetically activated oocytes, we observed a decrease at 9 h (P<0.05). In sperm-activated oocytes, ROS fluctuated throughout the 24 h, presenting peaks around 7, 19, and 24 h (P<0.05), while in parthenogenetic activation, peaks were detected at 7, 11, and 17 h (P<0.05). In the present work, we found clear distinctive metabolic patterns between normal and parthenogenetic zygotes. Oxidative activity and ROS production are an integral part of bovine zygote behavior, and defining a temporal pattern of change may be linked with developmental competence.

  3. Variations in Fe and S redox states in ocean island basalts

    NASA Astrophysics Data System (ADS)

    Brounce, M. N.; Peterson, M. E.; Stolper, E. M.; Eiler, J. M.

    2016-12-01

    The chemical and isotopic compositions of ocean island basalts (OIB) suggest that their mantle sources contain imprints of subducted sediments, altered oceanic crust, undegassed mantle, and/or residues of continental crust formation. By comparing the oxygen fugacities (fO2) of OIBs to the extent to which they contain these imprints, it may be possible to relate specific compositions to spatial and temporal variations in source fO2. To explore this, we present µ-XANES measurements of the oxidation states of Fe and S from pillow glass and olivine-hosted melt inclusions from the Reykjanes Ridge, Mauna Kea, Kilauea, Loihi, Hawaiian South Arch, Reunion Island, and the Ontong Java Plateau; we then compare these measurements with previous determinations of the chemical and isotopic compositions of these OIBs. Reykjanes Ridge and Ontong Java glasses have Fe and S redox states that are similar to MORBs; although these glasses show evidence for assimilation of seawater or crustal components, there is no relationship between indices of assimilation (18O/16O, Cl) and Fe or S redox states. This indicates that assimilation in these settings does not have a major effect on magmatic fO2. Mauna Kea and Kilauea glasses affected by S+H2O degassing have decreased Fe and S redox states, but the least degassed samples from both volcanoes are similar to each other and more oxidized than MORB, Reykjanes Ridge, and Ontong Java glasses. Loihi and South Arch glasses have not lost significant S and H2O to degassing, and they record fO2s similar to the least degassed Mauna Kea and Kilauea glasses. Olivine-hosted melt inclusions from Reunion range in Fe redox from similar to MORBs to more oxidized than Hawaiian volcanoes. These data demonstrate that OIBs are heterogeneous in Fe and S redox states. Although more data are needed for the various OIB end members, with the exception of the two most reduced glasses from Reunion, the data thus far suggest a rough positive correlation between 87Sr/86

  4. Status of the intracellular gate in the activated-not-open state of shaker K+ channels.

    PubMed

    del Camino, Donato; Kanevsky, Max; Yellen, Gary

    2005-11-01

    Voltage-dependent K+ channels like Shaker use an intracellular gate to control ion flow through the pore. When the membrane voltage becomes more positive, these channels traverse a series of closed conformations before the final opening transition. Does the intracellular gate undergo conformational changes before channel opening? To answer this question we introduced cysteines into the intracellular end of the pore and studied their chemical modification in conditions favoring each of three distinct states, the open state, the resting closed state, and the activated-not-open state (the closed state adjacent to the open state). We used two independent ways to isolate the channels in the activated-not-open state. First, we used mutations in S4 (ILT; Smith-Maxwell, C.J., J.L. Ledwell, and R.W. Aldrich. 1998. J. Gen. Physiol. 111:421-439; Ledwell, J.L., and R.W. Aldrich. 1999. J. Gen. Physiol. 113:389-414) that separate the final opening step from earlier charge-movement steps. Second, we used the open channel blocker 4-aminopyridine (4-AP), which has been proposed to promote closure of the intracellular gate and thus specifically to stabilize the activated-not-open state of the channels. Supporting this proposed mechanism, we found that 4-AP enters channels only after opening, remaining trapped in closed channels, and that in the open state it competes with tetraethylammonium for binding. Using these tools, we found that in the activated-not-open state, a cysteine located at a position considered to form part of the gate (Shaker 478) showed higher reactivity than in either the open or the resting closed states. Additionally, we have found that in this activated state the intracellular gate continued to prevent access to the pore by molecules as small as Cd2+ ions. Our results suggest that the intracellular opening to the pore undergoes some rearrangements in the transition from the resting closed state to the activated-not-open state, but throughout this process the

  5. Status of the Intracellular Gate in the Activated-not-open State of Shaker K+ Channels

    PubMed Central

    del Camino, Donato; Kanevsky, Max; Yellen, Gary

    2005-01-01

    Voltage-dependent K+ channels like Shaker use an intracellular gate to control ion flow through the pore. When the membrane voltage becomes more positive, these channels traverse a series of closed conformations before the final opening transition. Does the intracellular gate undergo conformational changes before channel opening? To answer this question we introduced cysteines into the intracellular end of the pore and studied their chemical modification in conditions favoring each of three distinct states, the open state, the resting closed state, and the activated-not-open state (the closed state adjacent to the open state). We used two independent ways to isolate the channels in the activated-not-open state. First, we used mutations in S4 (ILT; Smith-Maxwell, C.J., J.L. Ledwell, and R.W. Aldrich. 1998. J. Gen. Physiol. 111:421–439; Ledwell, J.L., and R.W. Aldrich. 1999. J. Gen. Physiol. 113:389–414) that separate the final opening step from earlier charge-movement steps. Second, we used the open channel blocker 4-aminopyridine (4-AP), which has been proposed to promote closure of the intracellular gate and thus specifically to stabilize the activated-not-open state of the channels. Supporting this proposed mechanism, we found that 4-AP enters channels only after opening, remaining trapped in closed channels, and that in the open state it competes with tetraethylammonium for binding. Using these tools, we found that in the activated-not-open state, a cysteine located at a position considered to form part of the gate (Shaker 478) showed higher reactivity than in either the open or the resting closed states. Additionally, we have found that in this activated state the intracellular gate continued to prevent access to the pore by molecules as small as Cd2+ ions. Our results suggest that the intracellular opening to the pore undergoes some rearrangements in the transition from the resting closed state to the activated-not-open state, but throughout this process

  6. Probing redox states in the ancient and modern crust and possible biosphere-lithosphere interactions

    NASA Astrophysics Data System (ADS)

    Trail, D.

    2015-12-01

    The oxidation states of modern-day terrestrial environments are broadly constrained, though we are at the earliest stages of directly quantifying redox states during the first 700 million years. Redox states are constrainable through a combination of high temperature laboratory experiments, analyses of detrital Hadean zircon, and younger well-studied zircons and their host rocks. The redox state of the solid earth and the biosphere are believed to be interwoven: how might we exploit this to probe for the existence of possible biosphere-lithosphere interactions on the early Earth? Some insight comes from the investigation of "modern-day" zircon-bearing rocks and the new application of techniques that allow us to directly probe element valence as a proxy for magma redox state (XANES). Other insights are possible through the study of young ~400 Ma (S)edimentary- and (I)gneous-type granitoids from Lachlan Fold Belt (LFB), where the magma chemical properties in the former may be influenced by the assimilation of sedimentary material containing organic matter. We observe that zircons from LFB S-type granitoids formed under more reducing conditions when compared to LFB zircon formed in I-type granitoids. This observation, while reflecting 9 granitoids and 289 analyses of zircons where over 400 different plutons have been identified, is consistent with the incorporation of (reduced) organic matter in the former and highlights one possible manner in which life may influence the composition of igneous minerals. The chemical properties of rocks or igneous minerals such as zircon may extend the search for ancient biological activity to the earliest period of known igneous activity, which dates back to ~4.4 billion years ago. If organic matter was incorporated into Hadean sediments that were then buried and melted, then these biological remnants could imprint a chemical signature within the subsequent melt and the resulting crystal assemblage, including zircon.

  7. The influence of the redox state of follicular fluid albumin on the viability of aspirated human oocytes.

    PubMed

    Otsuki, Junko; Nagai, Yasushi; Matsuyama, Yukie; Terada, Tomoyoshi; Era, Seiichi

    2012-06-01

    A number of reports have suggested that the oxidative state of human albumin in serum and in some body fluids is associated with cell damage. However there are no reports on the redox state of human follicular fluid (FF) and its influence on oocyte viability. The aim of this study was to examine the relationship between the redox state of FF and serum on oocyte viability. The cytoplasmic condition of oocytes was evaluated microscopically at collection in 117 women. Deteriorating oocytes were recognized by degenerative changes in their cytoplasm. The redox state of FFs that yielded degenerated oocytes was evaluated and compared with fluids containing normal oocytes. The redox state of the corresponding FF and serum, at the time of oocyte retrieval, was analyzed by high performance liquid chromatography. The redox state of FF that contained degenerated oocytes was found to have a significantly elevated oxidized state compared with the FFs that yielded normal oocytes. Also the albumin in the FF of patients was found to be predominantly in the reduced state compared with that in their serum at the time of oocyte retrieval. In addition, increasing age and endometriosis were found to shift the redox of serum to the oxidative state. We propose that the reduced state of albumin in FF may play an important role in protecting oocytes from oxidative damage.

  8. Redox states of Desulfovibrio vulgaris DsrC, a key protein in dissimilatory sulfite reduction

    SciTech Connect

    Venceslau, Sofia S.; Cort, John R.; Baker, Erin Shammel; Chu, Rosalie K.; Robinson, Errol W.; Dahl, Christiane; Saraiva, Ligia M.; Pereira, Ines Ac

    2013-11-29

    Dissimilatory reduction of sulfite is carried out by the siroheme enzyme DsrAB, with the involvement of the protein DsrC having two conserved cysteine residues. Here, we report a study of the distribution of DsrC in cell extracts, a cysteine-labelling gel-shift assay to monitor its redox state and behaviour, and procedures to produce the different redox forms. We show that, in the model sulfate reducer Desulfovibrio vulgaris, the majority of DsrC is not associated with DsrAB and is thus free to interact with other proteins. In addition, we successfully produced DsrC with an intramolecular disulfide bond (oxidized state) by treatment with arginine.

  9. Optical imaging of mitochondrial redox state in rodent model of retinitis pigmentosa

    NASA Astrophysics Data System (ADS)

    Maleki, Sepideh; Gopalakrishnan, Sandeep; Ghanian, Zahra; Sepehr, Reyhaneh; Schmitt, Heather; Eells, Janis; Ranji, Mahsa

    2013-01-01

    Oxidative stress (OS) and mitochondrial dysfunction contribute to photoreceptor cell loss in retinal degenerative disorders. The metabolic state of the retina in a rodent model of retinitis pigmentosa (RP) was investigated using a cryo-fluorescence imaging technique. The mitochondrial metabolic coenzymes nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) are autofluorescent and can be monitored without exogenous labels using optical techniques. The cryo-fluorescence redox imaging technique provides a quantitative assessment of the metabolism. More specifically, the ratio of the fluorescence intensity of these fluorophores (NADH/FAD), the NADH redox ratio (RR), is a marker of the metabolic state of the tissue. The NADH RR and retinal function were examined in an established rodent model of RP, the P23H rat compared to that of nondystrophic Sprague-Dawley (SD) rats. The NADH RR mean values were 1.11±0.03 in the SD normal and 0.841±0.01 in the P23H retina, indicating increased OS in the P23H retina. Electroretinographic data revealed a significant reduction in photoreceptor function in P23H animals compared to SD nozrmal rats. Thus, cryo-fluorescence redox imaging was used as a quantitative marker of OS in eyes from transgenic rats and demonstrated that alterations in the oxidative state of eyes occur during the early stages of RP.

  10. Surface Fluorescence Studies of Tissue Mitochondrial Redox State in Isolated Perfused Rat Lungs

    PubMed Central

    Staniszewski, Kevin; Audi, Said H.; Sepehr, Reyhaneh; Jacobs, Elizabeth R.; Ranji, Mahsa

    2012-01-01

    We designed a fiber-optic-based optoelectronic fluorometer to measure emitted fluorescence from the auto-fluorescent electron carriers NADH and FAD of the mitochondrial electron transport chain (ETC). The ratio of NADH to FAD is called the redox ratio (RR = NADH/FAD) and is an indicator of the oxidoreductive state of tissue. We evaluated the fluorometer by measuring the fluorescence intensities of NADH and FAD at the surface of isolated, perfused rat lungs. Alterations of lung mitochondrial metabolic state were achieved by the addition of rotenone (complex I inhibitor), potassium cyanide (KCN, complex IV inhibitor) and/or pentachlorophenol (PCP, uncoupler) into the perfusate recirculating through the lung. Rotenone- or KCN-containing perfusate increased RR by 21% and 30%, respectively. In contrast, PCP-containing perfusate decreased RR by 27%. These changes are consistent with the established effects of rotenone, KCN, and PCP on the redox status of the ETC. Addition of blood to perfusate quenched NADH and FAD signal, but had no effect of RR. This study demonstrates the capacity of fluorometry to detect a change in mitochondrial redox state in isolated perfused lungs, and suggests the potential of fluorometry for use in in vivo experiments to extract a sensitive measure of lung tissue’s health in real-time. PMID:23238793

  11. Crucial yet divergent roles of mitochondrial redox state in skeletal muscle vs. brown adipose tissue energetics.

    PubMed

    Mailloux, Ryan J; Adjeitey, Cyril Nii-Klu; Xuan, Jian Ying; Harper, Mary-Ellen

    2012-01-01

    Reduced glutathione (GSH) is the major determinant of redox balance in mitochondria and as such is fundamental in the control of cellular bioenergetics. GSH is also the most important nonprotein antioxidant molecule in cells. Surprisingly, the effect of redox environment has never been examined in skeletal muscle and brown adipose tissue (BAT), two tissues that have exceptional dynamic range and that are relevant to the development of obesity and related diseases. Here, we show that the redox environment plays crucial, yet divergent, roles in modulating mitochondrial bioenergetics in skeletal muscle and BAT. Skeletal muscle mitochondria were found to naturally have a highly reduced environment (GSH/GSSG≈46), and this was associated with fairly high (∼40%) rates of state 4 (nonphosphorylating) respiration and decreased reactive oxygen species (ROS) emission. The deglutathionylation of uncoupling protein 3 (UCP3) following an increase in the reductive potential of mitochondria results in a further increase in nonphosphorylating respiration (∼20% in situ). BAT mitochondria were found to have a much more oxidized status (GSH/GSSG≈13) and had basal reactive oxygen species emission that was higher (∼250% increase in ROS generation) than that in skeletal muscle mitochondria. When redox status was subsequently increased (i.e., more reduced), UCP1-mediated uncoupling was more sensitive to GDP inhibition. Surprisingly, BAT was found to be devoid of glutaredoxin-2 (Grx2) expression, while there was abundant expression in skeletal muscle. Taken together, these findings reveal the importance of redox environment in controlling bioenergetic functions in both tissues, and the highly unique characteristics of BAT in this regard.

  12. [Redox Molecular Imaging Using ReMI].

    PubMed

    Hyodo, Fuminori; Ito, Shinji; Utsumi, Hideo

    2015-01-01

    Tissue redox status is one of the most important parameters to maintain homeostasis in the living body. Numerous redox reactions are involved in metabolic processes, such as energy production in the mitochondrial electron transfer system. A variety of intracellular molecules such as reactive oxygen species, glutathione, thioredoxins, NADPH, flavins, and ascorbic acid may contribute to the overall redox status in tissues. Breakdown of redox balance may lead to oxidative stress and can induce many pathological conditions such as cancer, neurological disorders, and aging. Therefore imaging of tissue redox status and monitoring antioxidant levels in living organisms can be useful in the diagnosis of disease states and assessment of treatment response. In vivo redox molecular imaging technology such as electron spin resonance imaging (ESRI), magnetic resonance imaging (MRI), and dynamic nuclear polarization (DNP)-MRI (redox molecular imaging; ReMI) is emerging as a viable redox status imaging modality. This review focuses on the application of magnetic resonance technologies using MRI or DNP-MRI and redox-sensitive contrast agents.

  13. Intermediate and stable redox states of cytochrome c studied by low temperature resonance Raman spectroscopy.

    PubMed Central

    Cartling, B

    1983-01-01

    Stabilized intermediate redox states of cytochrome c are generated by radiolytic reduction of initially oxidized enzyme in glass matrices at liquid nitrogen temperature. In the intermediate states the heme group is reduced by hydrated electrons, whereas the protein conformation is restrained close to its oxidized form by the low-temperature glass matrix. The intermediate and stable redox states of cytochrome c at neutral and alkaline pH are studied by low-temperature resonance Raman spectroscopy using excitations in resonance with the B (Soret) and Q1 (beta) optical transitions. The assignments of the cytochrome c resonance Raman bands are discussed. The observed spectral characteristics of the intermediate states as well as of the alkaline transition in the oxidized state are interpreted in terms of oxidation-state marker modes, spin-state marker modes, heme iron--axial ligand stretching modes, totally symmetric in-plane porphyrin modes, nontotally symmetric in-plane modes, and out-of-plane modes. PMID:6311300

  14. Effect of severe environmental thermal stress on redox state in salmon.

    PubMed

    Nakano, Toshiki; Kameda, Masumi; Shoji, Yui; Hayashi, Satoshi; Yamaguchi, Toshiyasu; Sato, Minoru

    2014-01-01

    Fish are exposed to many kinds of environmental stressors and the chances of succumbing to infectious diseases may be increased a result. For example, an acute increase in temperature can induce numerous physiological changes in the body. In the present study, we examined the redox state in response to a severe acute stress resulting from heat shock in teleost coho salmon (Oncorhynchus kisutch). The plasma lipid peroxides levels in fish gradually increased after heat shock treatment. By 2.5 h post-heat stress, plasma glutathione (GSH) levels had decreased, but they had returned to basal levels by 17.5 h post-stress. Plasma superoxide dismutase activities in stressed fish were significantly increased compared with those in control fish at 17.5 h post-stress, but had returned to basal levels by 48 h post-stress. Expression levels of hepatic GSH and heat shock protein 70 gradually increased after heat shock treatment. These results concerning the changing patterns of multiple important redox-related biomarkers suggest that severe thermal stressors can affect the redox state and induce oxidative stress in ectothermal animals, such as fish, in vivo. Hence, manipulation of appropriate thermal treatment may possibly be useful to control fish fitness.

  15. Effect of severe environmental thermal stress on redox state in salmon

    PubMed Central

    Nakano, Toshiki; Kameda, Masumi; Shoji, Yui; Hayashi, Satoshi; Yamaguchi, Toshiyasu; Sato, Minoru

    2014-01-01

    Fish are exposed to many kinds of environmental stressors and the chances of succumbing to infectious diseases may be increased a result. For example, an acute increase in temperature can induce numerous physiological changes in the body. In the present study, we examined the redox state in response to a severe acute stress resulting from heat shock in teleost coho salmon (Oncorhynchus kisutch). The plasma lipid peroxides levels in fish gradually increased after heat shock treatment. By 2.5 h post-heat stress, plasma glutathione (GSH) levels had decreased, but they had returned to basal levels by 17.5 h post-stress. Plasma superoxide dismutase activities in stressed fish were significantly increased compared with those in control fish at 17.5 h post-stress, but had returned to basal levels by 48 h post-stress. Expression levels of hepatic GSH and heat shock protein 70 gradually increased after heat shock treatment. These results concerning the changing patterns of multiple important redox-related biomarkers suggest that severe thermal stressors can affect the redox state and induce oxidative stress in ectothermal animals, such as fish, in vivo. Hence, manipulation of appropriate thermal treatment may possibly be useful to control fish fitness. PMID:25009778

  16. Glutaredoxin exerts an antiapoptotic effect by regulating the redox state of Akt.

    PubMed

    Murata, Hiroaki; Ihara, Yoshito; Nakamura, Hajime; Yodoi, Junji; Sumikawa, Koji; Kondo, Takahito

    2003-12-12

    Glutaredoxin (GRX) is a small dithiol protein involved in various cellular functions, including the redox regulation of certain enzyme activities. GRX functions via a disulfide exchange reaction by utilizing the active site Cys-Pro-Tyr-Cys. Here we demonstrated that overexpression of GRX protected cells from hydrogen peroxide (H2O2)-induced apoptosis by regulating the redox state of Akt. Akt was transiently phosphorylated, dephosphorylated, and then degraded in cardiac H9c2 cells undergoing H2O2-induced apoptosis. Under stress, Akt underwent disulfide bond formation between Cys-297 and Cys-311 and dephosphorylation in accordance with an increased association with protein phosphatase 2A. Overexpression of GRX protected Akt from H2O2-induced oxidation and suppressed recruitment of protein phosphatase 2A to Akt, resulting in a sustained phosphorylation of Akt and inhibition of apoptosis. This effect was reversed by cadmium, an inhibitor of GRX. Furthermore an in vitro assay revealed that GRX reduced oxidized Akt in concert with glutathione, NADPH, and glutathione-disulfide reductase. Thus, GRX plays an important role in protecting cells from apoptosis by regulating the redox state of Akt.

  17. Different carbon sources affect lifespan and protein redox state during Saccharomyces cerevisiae chronological ageing.

    PubMed

    Magherini, F; Carpentieri, A; Amoresano, A; Gamberi, T; De Filippo, C; Rizzetto, L; Biagini, M; Pucci, P; Modesti, A

    2009-03-01

    In this study, a proteomic approach that combines selective labelling of proteins containing reduced cysteine residues with two-dimensional electrophoresis/mass spectrometry was used to evaluate the redox state of protein cysteines during chronological ageing in Saccharomyces cerevisiae. The procedure was developed on the grounds that biotin-conjugated iodoacetamide (BIAM) specifically reacts with reduced cysteine residues. BIAM-labelled proteins can then be selectively isolated by streptavidin affinity capture. We compared cells grown on 2% glucose in the exponential phase and during chronological ageing and we found that many proteins undergo cysteine oxidation. The target proteins include enzymes involved in glucose metabolism. Both caloric restriction and growth on glycerol resulted in a decrease in the oxidative modification. Furthermore, in these conditions a reduced production of ROS and a more negative glutathione half cell redox potential were observed.

  18. Mitochondrial H2O2 emission and cellular redox state link excess fat intake to insulin resistance in both rodents and humans

    PubMed Central

    Anderson, Ethan J.; Lustig, Mary E.; Boyle, Kristen E.; Woodlief, Tracey L.; Kane, Daniel A.; Lin, Chien-Te; Price, Jesse W.; Kang, Li; Rabinovitch, Peter S.; Szeto, Hazel H.; Houmard, Joseph A.; Cortright, Ronald N.; Wasserman, David H.; Neufer, P. Darrell

    2009-01-01

    High dietary fat intake leads to insulin resistance in skeletal muscle, and this represents a major risk factor for type 2 diabetes and cardiovascular disease. Mitochondrial dysfunction and oxidative stress have been implicated in the disease process, but the underlying mechanisms are still unknown. Here we show that in skeletal muscle of both rodents and humans, a diet high in fat increases the H2O2-emitting potential of mitochondria, shifts the cellular redox environment to a more oxidized state, and decreases the redox-buffering capacity in the absence of any change in mitochondrial respiratory function. Furthermore, we show that attenuating mitochondrial H2O2 emission, either by treating rats with a mitochondrial-targeted antioxidant or by genetically engineering the overexpression of catalase in mitochondria of muscle in mice, completely preserves insulin sensitivity despite a high-fat diet. These findings place the etiology of insulin resistance in the context of mitochondrial bioenergetics by demonstrating that mitochondrial H2O2 emission serves as both a gauge of energy balance and a regulator of cellular redox environment, linking intracellular metabolic balance to the control of insulin sensitivity. PMID:19188683

  19. Mitochondrial H2O2 emission and cellular redox state link excess fat intake to insulin resistance in both rodents and humans.

    PubMed

    Anderson, Ethan J; Lustig, Mary E; Boyle, Kristen E; Woodlief, Tracey L; Kane, Daniel A; Lin, Chien-Te; Price, Jesse W; Kang, Li; Rabinovitch, Peter S; Szeto, Hazel H; Houmard, Joseph A; Cortright, Ronald N; Wasserman, David H; Neufer, P Darrell

    2009-03-01

    High dietary fat intake leads to insulin resistance in skeletal muscle, and this represents a major risk factor for type 2 diabetes and cardiovascular disease. Mitochondrial dysfunction and oxidative stress have been implicated in the disease process, but the underlying mechanisms are still unknown. Here we show that in skeletal muscle of both rodents and humans, a diet high in fat increases the H(2)O(2)-emitting potential of mitochondria, shifts the cellular redox environment to a more oxidized state, and decreases the redox-buffering capacity in the absence of any change in mitochondrial respiratory function. Furthermore, we show that attenuating mitochondrial H(2)O(2) emission, either by treating rats with a mitochondrial-targeted antioxidant or by genetically engineering the overexpression of catalase in mitochondria of muscle in mice, completely preserves insulin sensitivity despite a high-fat diet. These findings place the etiology of insulin resistance in the context of mitochondrial bioenergetics by demonstrating that mitochondrial H(2)O(2) emission serves as both a gauge of energy balance and a regulator of cellular redox environment, linking intracellular metabolic balance to the control of insulin sensitivity.

  20. Apocynin and Nox2 regulate NF-κB by modifying thioredoxin-1 redox-state

    PubMed Central

    Trevelin, Silvia Cellone; dos Santos, Célio Xavier; Ferreira, Raphael Gomes; de Sá Lima, Larissa; Silva, Rangel Leal; Scavone, Cristoforo; Curi, Rui; Alves-Filho, José Carlos; Cunha, Thiago Mattar; Roxo-Júnior, Pérsio; Cervi, Maria-Célia; Laurindo, Francisco Rafael Martins; Hothersall, John Stephen; Cobb, Andrew M.; Zhang, Min; Ivetic, Aleksandar; Shah, Ajay M.; Lopes, Lucia Rossetti; Cunha, Fernando Queiroz

    2016-01-01

    The reactive-oxygen-species-(ROS)-generating-enzyme Nox2 is essential for leukocyte anti-microbial activity. However its role in cellular redox homeostasis and, consequently, in modulating intracellular signaling pathways remains unclear. Herein, we show Nox2 activation favors thioredoxin-1 (TRX-1)/p40phox interaction, which leads to exclusion of TRX-1 from the nucleus. In contrast, the genetic deficiency of Nox2 or its pharmacological inhibition with apocynin (APO) results in reductive stress after lipopolysaccharide-(LPS)-cell stimulation, which causes nuclear accumulation of TRX-1 and enhanced transcription of inflammatory mediators through nuclear-factor-(NF)-κB. The NF-κB overactivation is prevented by TRX-1 oxidation using inhibitors of thioredoxin reductase-1 (TrxR-1). The Nox2/TRX-1/NF-κB intracellular signaling pathway is involved in the pathophysiology of chronic granulomatous disease (CGD) and sepsis. In fact, TrxR-1 inhibition prevents nuclear accumulation of TRX-1 and LPS-stimulated hyperproduction of tumor-necrosis-factor-(TNF)-α by monocytes and neutrophils purified from blood of CGD patients, who have deficient Nox2 activity. TrxR-1 inhibitors, either lanthanum chloride (LaCl3) or auranofin (AUR), also increase survival rates of mice undergoing cecal-ligation-and-puncture-(CLP). Therefore, our results identify a hitherto unrecognized Nox2-mediated intracellular signaling pathway that contributes to hyperinflammation in CGD and in septic patients. Additionally, we suggest that TrxR-1 inhibitors could be potential drugs to treat patients with sepsis, particularly in those with CGD. PMID:27698473

  1. The redox state of arc mantle using Zn/Fe systematics.

    PubMed

    Lee, Cin-Ty A; Luffi, Peter; Le Roux, Véronique; Dasgupta, Rajdeep; Albaréde, Francis; Leeman, William P

    2010-12-02

    Many arc lavas are more oxidized than mid-ocean-ridge basalts and subduction introduces oxidized components into the mantle. As a consequence, the sub-arc mantle wedge is widely believed to be oxidized. The Fe oxidation state of sub-arc mantle is, however, difficult to determine directly, and debate persists as to whether this oxidation is intrinsic to the mantle source. Here we show that Zn/Fe(T) (where Fe(T) = Fe(2+) + Fe(3+)) is redox-sensitive and retains a memory of the valence state of Fe in primary arc basalts and their mantle sources. During melting of mantle peridotite, Fe(2+) and Zn behave similarly, but because Fe(3+) is more incompatible than Fe(2+), melts generated in oxidized environments have low Zn/Fe(T). Primitive arc magmas have identical Zn/Fe(T) to mid-ocean-ridge basalts, suggesting that primary mantle melts in arcs and ridges have similar Fe oxidation states. The constancy of Zn/Fe(T) during early differentiation involving olivine requires that Fe(3+)/Fe(T) remains low in the magma. Only after progressive fractionation does Fe(3+)/Fe(T) increase and stabilize magnetite as a fractionating phase. These results suggest that subduction of oxidized crustal material may not significantly alter the redox state of the mantle wedge. Thus, the higher oxidation states of arc lavas must be in part a consequence of shallow-level differentiation processes, though such processes remain poorly understood.

  2. Selenium- and tellurium-containing multifunctional redox agents as biochemical redox modulators with selective cytotoxicity.

    PubMed

    Jamier, Vincent; Ba, Lalla A; Jacob, Claus

    2010-09-24

    Various human diseases, including different types of cancer, are associated with a disturbed intracellular redox balance and oxidative stress (OS). The past decade has witnessed the emergence of redox-modulating compounds able to utilize such pre-existing disturbances in the redox state of sick cells for therapeutic advantage. Selenium- and tellurium-based agents turn the oxidizing redox environment present in certain cancer cells into a lethal cocktail of reactive species that push these cells over a critical redox threshold and ultimately kill them through apoptosis. This kind of toxicity is highly selective: normal, healthy cells remain largely unaffected, since changes to their naturally low levels of oxidizing species produce little effect. To further improve selectivity, multifunctional sensor/effector agents are now required that recognize the biochemical signature of OS in target cells. The synthesis of such compounds provides interesting challenges for chemistry in the future.

  3. Three Redox States of Trypanosoma brucei Alternative Oxidase Identified by Infrared Spectroscopy and Electrochemistry

    PubMed Central

    Maréchal, Amandine; Kido, Yasutoshi; Kita, Kiyoshi; Moore, Anthony L.; Rich, Peter R.

    2009-01-01

    Electrochemistry coupled with Fourier transform infrared (IR) spectroscopy was used to investigate the redox properties of recombinant alternative ubiquinol oxidase from Trypanosoma brucei, the organism responsible for African sleeping sickness. Stepwise reduction of the fully oxidized resting state of recombinant alternative ubiquinol oxidase revealed two distinct IR redox difference spectra. The first of these, signal 1, titrates in the reductive direction as an n = 2 Nernstian component with an apparent midpoint potential of 80 mV at pH 7.0. However, reoxidation of signal 1 in the same potential range under anaerobic conditions did not occur and only began with potentials in excess of 500 mV. Reoxidation by introduction of oxygen was also unsuccessful. Signal 1 contained clear features that can be assigned to protonation of at least one carboxylate group, further perturbations of carboxylic and histidine residues, bound ubiquinone, and a negative band at 1554 cm−1 that might arise from a radical in the fully oxidized protein. A second distinct IR redox difference spectrum, signal 2, appeared more slowly once signal 1 had been reduced. This component could be reoxidized with potentials above 100 mV. In addition, when both signals 1 and 2 were reduced, introduction of oxygen caused rapid oxidation of both components. These data are interpreted in terms of the possible active site structure and mechanism of oxygen reduction to water. PMID:19767647

  4. Does light scattering affect the OCT quantitation of redox state of cytochrome oxidase in bone tissue?

    NASA Astrophysics Data System (ADS)

    Xu, Xiangqun; Wang, Ruikang K.; El Haj, Alicia

    2002-06-01

    In our previous report, we have presented the possibility of optical coherence tomography (OCT) to monitor the redox state of mitochondria enzyme Cytochrome oxidase (CytOx) in bone tissue. The previous results showed that reduction of the enzyme in periosteal tissue leads to a change in attenuation coefficient of 1.68 +/- 0.67mm-1 by OCT measurements. The new results from cultured cells fixed in 300 (mu) l agarose plug showed the difference in attenuation coefficient is 0.26+-0.10 mm-1 (n = 9) for 7x106 astrocytoma cells and 0.28+-0.13 mm-1 (n = 7) for 20x106 astrocytoma cells in agarose plug, respectively between cells with oxidised and reduced enzyme at 820nm. A decrease in attenuation coefficient of 0.35+-0.09 mm-1 (n = 4) for 10 million SKMES cells in agarose was also observed with the redox shift of CytOx. The absorption coefficient of the oxidized-reduced form of CytOx is measured approximately 8.4+-1.5x10-3/mm (n=3) and 8.2+-1.0x10-3/mm (n=3) at 820nm for astrocytoma cells and rat periosteum respectively by means of a biochemical assay. Thereby it can be seen that the change in attenuation coefficient of cultured cells with redox shift of CytOx mainly results from the scattering change.

  5. Optical cryo-imaging of kidney mitochondrial redox state in diabetic mice models

    NASA Astrophysics Data System (ADS)

    Maleki, S.; Sepehr, R.; Staniszewski, K.; Sheibani, N.; Sorenson, C. M.; Ranji, M.

    2012-03-01

    Oxidative stress (OS), which increases during diabetes, exacerbates the development and progression of diabetes complications including renal vascular and proximal tubule cell dysfunction. The objective of this study was to investigate the changes in the metabolic state of the tissue in diabetic mice kidneys using fluorescence imaging. Mitochondrial metabolic coenzymes NADH (Nicotinamide Adenine Dinucleotide), and FADH-2 (Flavin Adenine Dinucleotide) are autofluorescent and can be monitored without exogenous labels by optical techniques. The ratio of the fluorescence intensity of these fluorophores, (NADH/FAD), called the NADH redox ratio (RR), is a marker of metabolic state of a tissue. We examined mitochondrial redox states of kidneys from diabetic mice, Akita/+ and its control wild type (WT) for a group of 8- and 12-week-old mice. Average intensity and histogram of maximum projected images of FAD, NADH, and NADH RR were calculated for each kidney. Our results indicated a 17% decrease in the mean NADH RR of the kidney from 8-week-old mice compared with WT mice and, a 30% decrease in the mean NADH RR of kidney from12-week-old mice compared with WT mice. These results indicated an increase in OS in diabetic animals and its progression over time. Thus, NADH RR can be used as a hallmark of OS in diabetic kidney allowing temporal identification of oxidative state.

  6. New tools for redox biology: From imaging to manipulation.

    PubMed

    Bilan, Dmitry S; Belousov, Vsevolod V

    2016-12-06

    Redox reactions play a key role in maintaining essential biological processes. Deviations in redox pathways result in the development of various pathologies at cellular and organismal levels. Until recently, studies on transformations in the intracellular redox state have been significantly hampered in living systems. The genetically encoded indicators, based on fluorescent proteins, have provided new opportunities in biomedical research. The existing indicators already enable monitoring of cellular redox parameters in different processes including embryogenesis, aging, inflammation, tissue regeneration, and pathogenesis of various diseases. In this review, we summarize information about all genetically encoded redox indicators developed to date. We provide the description of each indicator and discuss its advantages and limitations, as well as points that need to be considered when choosing an indicator for a particular experiment. One chapter is devoted to the important discoveries that have been made by using genetically encoded redox indicators.

  7. Chromium basalts - Experimental determination of redox states and partitioning among synthetic silicate phases

    NASA Technical Reports Server (NTRS)

    Schreiber, H. D.; Haskin, L. A.

    1976-01-01

    Experiments were performed on silicate compositions in the forsterite-anorthite-silica and forsterite-anorthite-diopside systems to determine the relative amounts of Cr(II), Cr(III), and Cr(VI) over a wide range of oxygen partial pressures from 10 to the -10th to 1 atm at 1500 and 1550 C. Redox states were measured by visible absorption spectroscopy and electron paramagnetic resonance spectroscopy and titration. It was found that Cr is present almost exclusively as Cr(III) in terrestrial basaltic liquids and as a mixture of Cr(III) and Cr(II) in lunar basaltic liquids.

  8. Chromium basalts - Experimental determination of redox states and partitioning among synthetic silicate phases

    NASA Technical Reports Server (NTRS)

    Schreiber, H. D.; Haskin, L. A.

    1976-01-01

    Experiments were performed on silicate compositions in the forsterite-anorthite-silica and forsterite-anorthite-diopside systems to determine the relative amounts of Cr(II), Cr(III), and Cr(VI) over a wide range of oxygen partial pressures from 10 to the -10th to 1 atm at 1500 and 1550 C. Redox states were measured by visible absorption spectroscopy and electron paramagnetic resonance spectroscopy and titration. It was found that Cr is present almost exclusively as Cr(III) in terrestrial basaltic liquids and as a mixture of Cr(III) and Cr(II) in lunar basaltic liquids.

  9. Biredox ionic liquids with solid-like redox density in the liquid state for high-energy supercapacitors

    NASA Astrophysics Data System (ADS)

    Mourad, Eléonore; Coustan, Laura; Lannelongue, Pierre; Zigah, Dodzi; Mehdi, Ahmad; Vioux, André; Freunberger, Stefan A.; Favier, Frédéric; Fontaine, Olivier

    2017-04-01

    Kinetics of electrochemical reactions are several orders of magnitude slower in solids than in liquids as a result of the much lower ion diffusivity. Yet, the solid state maximizes the density of redox species, which is at least two orders of magnitude lower in liquids because of solubility limitations. With regard to electrochemical energy storage devices, this leads to high-energy batteries with limited power and high-power supercapacitors with a well-known energy deficiency. For such devices the ideal system should endow the liquid state with a density of redox species close to the solid state. Here we report an approach based on biredox ionic liquids to achieve bulk-like redox density at liquid-like fast kinetics. The cation and anion of these biredox ionic liquids bear moieties that undergo very fast reversible redox reactions. As a first demonstration of their potential for high-capacity/high-rate charge storage, we used them in redox supercapacitors. These ionic liquids are able to decouple charge storage from an ion-accessible electrode surface, by storing significant charge in the pores of the electrodes, to minimize self-discharge and leakage current as a result of retaining the redox species in the pores, and to raise working voltage due to their wide electrochemical window.

  10. Biredox ionic liquids with solid-like redox density in the liquid state for high-energy supercapacitors.

    PubMed

    Mourad, Eléonore; Coustan, Laura; Lannelongue, Pierre; Zigah, Dodzi; Mehdi, Ahmad; Vioux, André; Freunberger, Stefan A; Favier, Frédéric; Fontaine, Olivier

    2017-04-01

    Kinetics of electrochemical reactions are several orders of magnitude slower in solids than in liquids as a result of the much lower ion diffusivity. Yet, the solid state maximizes the density of redox species, which is at least two orders of magnitude lower in liquids because of solubility limitations. With regard to electrochemical energy storage devices, this leads to high-energy batteries with limited power and high-power supercapacitors with a well-known energy deficiency. For such devices the ideal system should endow the liquid state with a density of redox species close to the solid state. Here we report an approach based on biredox ionic liquids to achieve bulk-like redox density at liquid-like fast kinetics. The cation and anion of these biredox ionic liquids bear moieties that undergo very fast reversible redox reactions. As a first demonstration of their potential for high-capacity/high-rate charge storage, we used them in redox supercapacitors. These ionic liquids are able to decouple charge storage from an ion-accessible electrode surface, by storing significant charge in the pores of the electrodes, to minimize self-discharge and leakage current as a result of retaining the redox species in the pores, and to raise working voltage due to their wide electrochemical window.

  11. Ground-state thermodynamics of bistable redox-active donor-acceptor mechanically interlocked molecules.

    PubMed

    Fahrenbach, Albert C; Bruns, Carson J; Cao, Dennis; Stoddart, J Fraser

    2012-09-18

    Fashioned through billions of years of evolution, biological molecular machines, such as ATP synthase, myosin, and kinesin, use the intricate relative motions of their components to drive some of life's most essential processes. Having control over the motions in molecules is imperative for life to function, and many chemists have designed, synthesized, and investigated artificial molecular systems that also express controllable motions within molecules. Using bistable mechanically interlocked molecules (MIMs), based on donor-acceptor recognition motifs, we have sought to imitate the sophisticated nanoscale machines present in living systems. In this Account, we analyze the thermodynamic characteristics of a series of redox-switchable [2]rotaxanes and [2]catenanes. Control and understanding of the relative intramolecular movements of components in MIMs have been vital in the development of a variety of applications of these compounds ranging from molecular electronic devices to drug delivery systems. These bistable donor-acceptor MIMs undergo redox-activated switching between two isomeric states. Under ambient conditions, the dominant translational isomer, the ground-state coconformation (GSCC), is in equilibrium with the less favored translational isomer, the metastable-state coconformation (MSCC). By manipulating the redox state of the recognition site associated with the GSCC, we can stimulate the relative movements of the components in these bistable MIMs. The thermodynamic parameters of model host-guest complexes provide a good starting point to rationalize the ratio of GSCC to MSCC at equilibrium. The bistable [2]rotaxanes show a strong correlation between the relative free energies of model complexes and the ground-state distribution constants (K(GS)). This relationship does not always hold for bistable [2]catenanes, most likely because of the additional steric and electronic constraints present when the two rings are mechanically interlocked with each other

  12. Influence of the Phase State of Self-Assembling Redox Mediators on their Electrochemical Activity

    PubMed Central

    Muller, John P. E.; Aytar, Burcu S.; Kondo, Yukishige; Lynn, David M.; Abbott, Nicholas L.

    2014-01-01

    Self-assembling redox mediators have the potential to be broadly useful in a range of interfacial electrochemical contexts because the oxidation state and state of assembly of the mediator are closely coupled. In this paper, we report an investigation of the self-assembly of single- and double-tailed ferrocenyl amphiphiles (FTMA and BFDMA, respectively) at the surfaces of Pt electrodes and the impact of the dynamic assembled state of the amphiphiles on their rate of oxidation. We conclude that frozen aggregates of BFDMA adsorb to the surfaces of the Pt electrodes, and that slow dynamics of reorganization BFDMA within these aggregates limits the rate of electrooxidation of BFDMA. In contrast, FTMA, while forming assemblies on the surfaces of Pt electrodes, is characterized by fast reorganization dynamics and a corresponding rate of oxidation that is an order of magnitude greater than BFDMA. PMID:24882870

  13. In vivo monitoring of cellular energy metabolism using SoNar, a highly responsive sensor for NAD(+)/NADH redox state.

    PubMed

    Zhao, Yuzheng; Wang, Aoxue; Zou, Yejun; Su, Ni; Loscalzo, Joseph; Yang, Yi

    2016-08-01

    NADH and its oxidized form NAD(+) have a central role in energy metabolism, and their concentrations are often considered to be among the most important readouts of metabolic state. Here, we present a detailed protocol to image and monitor NAD(+)/NADH redox state in living cells and in vivo using a highly responsive, genetically encoded fluorescent sensor known as SoNar (sensor of NAD(H) redox). The chimeric SoNar protein was initially developed by inserting circularly permuted yellow fluorescent protein (cpYFP) into the NADH-binding domain of Rex protein from Thermus aquaticus (T-Rex). It functions by binding to either NAD(+) or NADH, thus inducing protein conformational changes that affect its fluorescent properties. We first describe steps for how to establish SoNar-expressing cells, and then discuss how to use the system to quantify the intracellular redox state. This approach is sensitive, accurate, simple and able to report subtle perturbations of various pathways of energy metabolism in real time. We also detail the application of SoNar to high-throughput chemical screening of candidate compounds targeting cell metabolism in a microplate-reader-based assay, along with in vivo fluorescence imaging of tumor xenografts expressing SoNar in mice. Typically, the approximate time frame for fluorescence imaging of SoNar is 30 min for living cells and 60 min for living mice. For high-throughput chemical screening in a 384-well-plate assay, the whole procedure generally takes no longer than 60 min to assess the effects of 380 compounds on cell metabolism.

  14. A Protocol for Electrochemical Evaluations and State of Charge Diagnostics of a Symmetric Organic Redox Flow Battery

    SciTech Connect

    Duan, Wentao; Vemuri, Rama S.; Hu, Dehong; Yang, Zheng; Wei, Xiaoliang

    2017-01-01

    Redox flow batteries have been considered as one of the most promising stationary energy storage solutions for improving the reliability of the power grid and deployment of renewable energy technologies. Among the many flow battery chemistries, nonaqueous flow batteries have the potential to achieve high energy density because of the broad voltage windows of nonaqueous electrolytes. However, significant technical hurdles exist currently limiting nonaqueous flow batteries to demonstrate their full potential, such as low redox concentrations, low operating currents, under-explored battery status monitoring, etc. In an attempt to address these limitations, we report a nonaqueous flow battery based on a highly soluble, redox-active organic nitronyl nitroxide radical compound, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO). This redox materials exhibits an ambipolar electrochemical property with two reversible redox pairs that are moderately separated by a voltage gap of ~1.7 V. Therefore, PTIO can serve as both anolyte and catholyte redox materials to form a symmetric flow battery chemistry, which affords the advantages such as high effective redox concentrations and low irreversible redox material crossover. The PTIO flow battery shows decent electrochemical cyclability under cyclic voltammetry and flow cell conditions; an improved redox concentration of 0.5 M PTIO and operational current density of 20 mA cm-2 were achieved in flow cell tests. Moreover, we show that Fourier transform infrared (FTIR) spectroscopy could measure the PTIO concentrations during the PTIO flow battery cycling and offer reasonably accurate detection of the battery state of charge (SOC) as cross-validated by electron spin resonance measurements. This study suggests FTIR can be used as a reliable online SOC sensor to monitor flow battery status and ensure battery operations stringently in a safe SOC range.

  15. Fruit ripening mutants reveal cell metabolism and redox state during ripening.

    PubMed

    Kumar, Vinay; Irfan, Mohammad; Ghosh, Sumit; Chakraborty, Niranjan; Chakraborty, Subhra; Datta, Asis

    2016-03-01

    Ripening which leads to fruit senescence is an inimitable process characterized by vivid changes in color, texture, flavor, and aroma of the fleshy fruits. Our understanding of the mechanisms underlying the regulation of fruit ripening and senescence is far from complete. Molecular and biochemical studies on tomato (Solanum lycopersicum) ripening mutants such as ripening inhibitor (rin), nonripening (nor), and never ripe (Nr) have been useful in our understanding of fruit development and ripening. The MADS-box transcription factor RIN, a global regulator of fruit ripening, is vital for the broad aspects of ripening, in both ethylene-dependent and independent manners. Here, we have carried out microarray analysis to study the expression profiles of tomato genes during ripening of wild type and rin mutant fruits. Analysis of the differentially expressed genes revealed the role of RIN in regulation of several molecular and biochemical events during fruit ripening including fruit specialized metabolism and cellular redox state. The role of reactive oxygen species (ROS) during fruit ripening and senescence was further examined by determining the changes in ROS level during ripening of wild type and mutant fruits and by analyzing expression profiles of the genes involved in maintaining cellular redox state. Taken together, our findings suggest an important role of ROS during fruit ripening and senescence, and therefore, modulation of ROS level during ripening could be useful in achieving desired fruit quality.

  16. Effect of protein malnutrition on redox state of the hippocampus of rat.

    PubMed

    Bonatto, Fernanda; Polydoro, Manuela; Andrades, Michael Everton; da Frota Júnior, Mário Luís Conte; Dal-Pizzol, Felipe; Rotta, Liane Nanci; Souza, Diogo Onofre; Perry, Marcos Luiz; Moreira, José Cláudio Fonseca

    2005-04-25

    The protein malnutrition is a worldwide problem, affecting mainly newborns and children of developing countries. This deficiency reaches the brain in the most critical period of the development. Various consequences are related to this insult, such as memory disturbance, learning, and behavioral impairment. Protein content of the diet plays an important role on antioxidant mechanisms. This study observed the effects of protein malnutrition on rat hippocampus redox state. Wistar rats were separate in four groups, receiving different diets: first group with 25% casein, protein deficient group with 8% casein, and the same two groups supplemented with methionine (0.15%). Diets were isocaloric and were administered since the prenatal period up to the sacrifice. Rats were decapitated at 21 or 75 days old and hippocampus were isolated for measuring the lipoperoxidation by TBARS method, protein oxidative damage by carbonyl (DNPH) levels, and the activities of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT). There was significant alterations in the activities of the enzyme SOD, lipoperoxidation, and protein oxidation in hippocampus of 21 and 75 day-old rats fed with 25% of protein with methionine and the groups fed with low levels of protein (8%) both supplemented or not with methionine. Our data suggest that both the content of protein in the diet and the essential amino acid methionine may alter the antioxidant system and the redox state of the brain.

  17. Origin of stabilization and destabilization in solid-state redox reaction of oxide ions for lithium-ion batteries

    PubMed Central

    Yabuuchi, Naoaki; Nakayama, Masanobu; Takeuchi, Mitsue; Komaba, Shinichi; Hashimoto, Yu; Mukai, Takahiro; Shiiba, Hiromasa; Sato, Kei; Kobayashi, Yuki; Nakao, Aiko; Yonemura, Masao; Yamanaka, Keisuke; Mitsuhara, Kei; Ohta, Toshiaki

    2016-01-01

    Further increase in energy density of lithium batteries is needed for zero emission vehicles. However, energy density is restricted by unavoidable theoretical limits for positive electrodes used in commercial applications. One possibility towards energy densities exceeding these limits is to utilize anion (oxide ion) redox, instead of classical transition metal redox. Nevertheless, origin of activation of the oxide ion and its stabilization mechanism are not fully understood. Here we demonstrate that the suppression of formation of superoxide-like species on lithium extraction results in reversible redox for oxide ions, which is stabilized by the presence of relatively less covalent character of Mn4+ with oxide ions without the sacrifice of electronic conductivity. On the basis of these findings, we report an electrode material, whose metallic constituents consist only of 3d transition metal elements. The material delivers a reversible capacity of 300 mAh g−1 based on solid-state redox reaction of oxide ions. PMID:28008955

  18. Origin of stabilization and destabilization in solid-state redox reaction of oxide ions for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Yabuuchi, Naoaki; Nakayama, Masanobu; Takeuchi, Mitsue; Komaba, Shinichi; Hashimoto, Yu; Mukai, Takahiro; Shiiba, Hiromasa; Sato, Kei; Kobayashi, Yuki; Nakao, Aiko; Yonemura, Masao; Yamanaka, Keisuke; Mitsuhara, Kei; Ohta, Toshiaki

    2016-12-01

    Further increase in energy density of lithium batteries is needed for zero emission vehicles. However, energy density is restricted by unavoidable theoretical limits for positive electrodes used in commercial applications. One possibility towards energy densities exceeding these limits is to utilize anion (oxide ion) redox, instead of classical transition metal redox. Nevertheless, origin of activation of the oxide ion and its stabilization mechanism are not fully understood. Here we demonstrate that the suppression of formation of superoxide-like species on lithium extraction results in reversible redox for oxide ions, which is stabilized by the presence of relatively less covalent character of Mn4+ with oxide ions without the sacrifice of electronic conductivity. On the basis of these findings, we report an electrode material, whose metallic constituents consist only of 3d transition metal elements. The material delivers a reversible capacity of 300 mAh g-1 based on solid-state redox reaction of oxide ions.

  19. Origin of stabilization and destabilization in solid-state redox reaction of oxide ions for lithium-ion batteries.

    PubMed

    Yabuuchi, Naoaki; Nakayama, Masanobu; Takeuchi, Mitsue; Komaba, Shinichi; Hashimoto, Yu; Mukai, Takahiro; Shiiba, Hiromasa; Sato, Kei; Kobayashi, Yuki; Nakao, Aiko; Yonemura, Masao; Yamanaka, Keisuke; Mitsuhara, Kei; Ohta, Toshiaki

    2016-12-23

    Further increase in energy density of lithium batteries is needed for zero emission vehicles. However, energy density is restricted by unavoidable theoretical limits for positive electrodes used in commercial applications. One possibility towards energy densities exceeding these limits is to utilize anion (oxide ion) redox, instead of classical transition metal redox. Nevertheless, origin of activation of the oxide ion and its stabilization mechanism are not fully understood. Here we demonstrate that the suppression of formation of superoxide-like species on lithium extraction results in reversible redox for oxide ions, which is stabilized by the presence of relatively less covalent character of Mn(4+) with oxide ions without the sacrifice of electronic conductivity. On the basis of these findings, we report an electrode material, whose metallic constituents consist only of 3d transition metal elements. The material delivers a reversible capacity of 300 mAh g(-1) based on solid-state redox reaction of oxide ions.

  20. Conformational dependence of intracellular NADH on metabolic state revealed by associated fluorescence anisotropy.

    PubMed

    Vishwasrao, Harshad D; Heikal, Ahmed A; Kasischke, Karl A; Webb, Watt W

    2005-07-01

    Global analysis of fluorescence and associated anisotropy decays of intrinsic tissue fluorescence offers a sensitive and non-invasive probe of the metabolically critical free/enzyme-bound states of intracellular NADH in neural tissue. Using this technique, we demonstrate that the response of NADH to the metabolic transition from normoxia to hypoxia is more complex than a simple increase in NADH concentration. The concentration of free NADH, and that of an enzyme bound form with a relatively low lifetime, increases preferentially over that of other enzyme bound NADH species. Concomitantly, the intracellular viscosity is reduced, likely due to the osmotic swelling of mitochondria. These conformation and environmental changes effectively decrease the tissue fluorescence average lifetime, causing the usual total fluorescence increase measurements to significantly underestimate the calculated concentration increase. This new discrimination of changes in NADH concentration, conformation, and environment provides the foundation for quantitative functional imaging of neural energy metabolism.

  1. Cyclic electron flow is redox-controlled but independent of state transition

    PubMed Central

    Takahashi, Hiroko; Clowez, Sophie; Wollman, Francis-André; Vallon, Olivier; Rappaport, Fabrice

    2013-01-01

    Photosynthesis is the biological process that feeds the biosphere with reduced carbon. The assimilation of CO2 requires the fine tuning of two co-existing functional modes: linear electron flow, which provides NADPH and ATP, and cyclic electron flow, which only sustains ATP synthesis. Although the importance of this fine tuning is appreciated, its mechanism remains equivocal. Here we show that cyclic electron flow as well as formation of supercomplexes, thought to contribute to the enhancement of cyclic electron flow, are promoted in reducing conditions with no correlation with the reorganization of the thylakoid membranes associated with the migration of antenna proteins towards Photosystems I or II, a process known as state transition. We show that cyclic electron flow is tuned by the redox power and this provides a mechanistic model applying to the entire green lineage including the vast majority of the cases in which state transition only involves a moderate fraction of the antenna. PMID:23760547

  2. Cyclic electron flow is redox-controlled but independent of state transition.

    PubMed

    Takahashi, Hiroko; Clowez, Sophie; Wollman, Francis-André; Vallon, Olivier; Rappaport, Fabrice

    2013-01-01

    Photosynthesis is the biological process that feeds the biosphere with reduced carbon. The assimilation of CO2 requires the fine tuning of two co-existing functional modes: linear electron flow, which provides NADPH and ATP, and cyclic electron flow, which only sustains ATP synthesis. Although the importance of this fine tuning is appreciated, its mechanism remains equivocal. Here we show that cyclic electron flow as well as formation of supercomplexes, thought to contribute to the enhancement of cyclic electron flow, are promoted in reducing conditions with no correlation with the reorganization of the thylakoid membranes associated with the migration of antenna proteins towards Photosystems I or II, a process known as state transition. We show that cyclic electron flow is tuned by the redox power and this provides a mechanistic model applying to the entire green lineage including the vast majority of the cases in which state transition only involves a moderate fraction of the antenna.

  3. Mapping of Redox State of Mitochondrial Cytochromes in Live Cardiomyocytes Using Raman Microspectroscopy

    PubMed Central

    Brazhe, Nadezda A.; Treiman, Marek; Brazhe, Alexey R.; Find, Ninett L.; Maksimov, Georgy V.; Sosnovtseva, Olga V.

    2012-01-01

    This paper presents a nonivasive approach to study redox state of reduced cytochromes , and of complexes II and III in mitochondria of live cardiomyocytes by means of Raman microspectroscopy. For the first time with the proposed approach we perform studies of rod- and round-shaped cardiomyocytes, representing different morphological and functional states. Raman mapping and cluster analysis reveal that these cardiomyocytes differ in the amounts of reduced cytochromes , and . The rod-shaped cardiomyocytes possess uneven distribution of reduced cytochromes , and in cell center and periphery. Moreover, by means of Raman spectroscopy we demonstrated the decrease in the relative amounts of reduced cytochromes , and in the rod-shaped cardiomyocytes caused by H2O2-induced oxidative stress before any visible changes. Results of Raman mapping and time-dependent study of reduced cytochromes of complexes II and III and cytochrome in cardiomyocytes are in a good agreement with our fluorescence indicator studies and other published data. PMID:22957018

  4. Changes in athlete's redox state induced by habitual and unaccustomed exercise.

    PubMed

    Djordjevic, Dusica Z; Cubrilo, Dejan G; Puzovic, Vladimir S; Vuletic, Milena S; Zivkovic, Vladimir I; Barudzic, Nevena S; Radovanovic, Dragan S; Djuric, Dragan M; Jakovljevic, Vladimir Lj

    2012-01-01

    The purpose of this study was to assess the influence of sport-specific and nonspecific bouts of exercise on athletes' redox state. Blood samples were collected from 14 handball players immediately before and after graded exercise test on the cycle ergometer and handball training. Levels of superoxide anion radical (O(2) (-)), hydrogen peroxide (H(2)O(2)), nitrites (NO(2) (-)) as markers of nitric oxide, index of lipid peroxidation (TBARs), glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) activity were determined. Exercise intensity was assessed by a system for heart rate (HR) monitoring. Average athletes' HR was not significantly different between protocols, but protocols differed in total time and time and percentage of time that athletes spent in every HR zone. The laboratory exercise test induced a significant increase of H(2)O(2) and TBARs as well as the decrease of the SOD and CAT activity, while after specific handball training, levels of NO(2) (-) were increased and SOD activity decreased. It seems that unaccustomed short intensive physical activity may induce oxidative stress in trained athletes, while sport-specific activity of longer duration and proper warm-up period may not. Further research should show whether the change of protocol testing and the implementation of various supplementations and manual methods can affect the redox equilibrium.

  5. Anr, the anaerobic global regulator, modulates the redox state and oxidative stress resistance in Pseudomonas extremaustralis.

    PubMed

    Tribelli, Paula M; Nikel, Pablo I; Oppezzo, Oscar J; López, Nancy I

    2013-02-01

    The role of Anr in oxidative stress resistance was investigated in Pseudomonas extremaustralis, a polyhydroxybutyrate-producing Antarctic bacterium. The absence of Anr caused increased sensitivity to hydrogen peroxide under low oxygen tension. This phenomenon was associated with a decrease in the redox ratio, higher oxygen consumption and higher reactive oxygen species production. Physiological responses of the mutant to the oxidized state included an increase in NADP(H) content, catalase activity and exopolysaccharide production. The wild-type strain showed a sharp decrease in the reduced thiol pool when exposed to hydrogen peroxide, not observed in the mutant strain. In silico analysis of the genome sequence of P. extremaustralis revealed putative Anr binding sites upstream from genes related to oxidative stress. Genes encoding several chaperones and cold shock proteins, a glutathione synthase, a sulfate transporter and a thiol peroxidase were identified as potential targets for Anr regulation. Our results suggest a novel role for Anr in oxidative stress resistance and in redox balance maintenance under conditions of restricted oxygen supply.

  6. Heterogeneity of intracellular polymer storage states in enhanced biological phosphorus removal (EBPR)--observation and modeling.

    PubMed

    Bucci, Vanni; Majed, Nehreen; Hellweger, Ferdi L; Gu, April Z

    2012-03-20

    A number of agent-based models (ABMs) for biological wastewater treatment processes have been developed, but their skill in predicting heterogeneity of intracellular storage states has not been tested against observations due to the lack of analytical methods for measuring single-cell intracellular properties. Further, several mechanisms can produce and maintain heterogeneity (e.g., different histories, uneven division) and their relative importance has not been explored. This article presents an ABM for the enhanced biological phosphorus removal (EBPR) treatment process that resolves heterogeneity in three intracellular polymer storage compounds (i.e., polyphosphate, polyhydroxybutyrate, and glycogen) in three functional microbial populations (i.e., polyphosphate-accumulating, glycogen-accumulating, and ordinary heterotrophic organisms). Model predicted distributions were compared to those based on single-cell estimates obtained using a Raman microscopy method for a laboratory-scale sequencing batch reactor (SBR) system. The model can reproduce many features of the observed heterogeneity. Two methods for introducing heterogeneity were evaluated. First, biological variability in individual cell behavior was simulated by randomizing model parameters (e.g., maximum acetate uptake rate) at division. This method produced the best fit to the data. An optimization algorithm was used to determine the best variability (i.e., coefficient of variance) for each parameter, which suggests large variability in acetate uptake. Second, biological variability in individual cell states was simulated by randomizing state variables (e.g., internal nutrient) at division, which was not able to maintain heterogeneity because the memory in the internal states is too short. These results demonstrate the ability of ABM to predict heterogeneity and provide insights into the factors that contribute to it. Comparison of the ABM with an equivalent population-level model illustrates the effect

  7. Resonance Raman quantification of the redox state of cytochromes b and c in-vivo and in-vitro.

    PubMed

    Kakita, Minoru; Kaliaperumal, Venkatesh; Hamaguchi, Hiro-o

    2012-01-01

    We observe the redox state changes with respiration of cytochromes b and c in mitochondria in a living Saccharomyces cerevisiae cell as well as in isolated mitochondria with the very use of Raman microspectroscopy. The possibility of monitoring the respiration activity of mitochondria in vivo and in vitro by Raman microspectroscopic quantification of the cytochrome redox states is suggested. It will lead to a new means to assess mitochondrial respiration activity in vivo and in vitro without using any labelling or genetic manipulation. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Ground-state kinetics of bistable redox-active donor-acceptor mechanically interlocked molecules.

    PubMed

    Fahrenbach, Albert C; Bruns, Carson J; Li, Hao; Trabolsi, Ali; Coskun, Ali; Stoddart, J Fraser

    2014-02-18

    The ability to design and confer control over the kinetics of theprocesses involved in the mechanisms of artificial molecular machines is at the heart of the challenge to create ones that can carry out useful work on their environment, just as Nature is wont to do. As one of the more promising forerunners of prototypical artificial molecular machines, chemists have developed bistable redox-active donor-acceptor mechanically interlocked molecules (MIMs) over the past couple of decades. These bistable MIMs generally come in the form of [2]rotaxanes, molecular compounds that constitute a ring mechanically interlocked around a dumbbell-shaped component, or [2]catenanes, which are composed of two mechanically interlocked rings. As a result of their interlocked nature, bistable MIMs possess the inherent propensity to express controllable intramolecular, large-amplitude, and reversible motions in response to redox stimuli. In this Account, we rationalize the kinetic behavior in the ground state for a large assortment of these types of bistable MIMs, including both rotaxanes and catenanes. These structures have proven useful in a variety of applications ranging from drug delivery to molecular electronic devices. These bistable donor-acceptor MIMs can switch between two different isomeric states. The favored isomer, known as the ground-state co-conformation (GSCC) is in equilibrium with the less favored metastable state co-conformation (MSCC). The forward (kf) and backward (kb) rate constants associated with this ground-state equilibrium are intimately connected to each other through the ground-state distribution constant, KGS. Knowing the rate constants that govern the kinetics and bring about the equilibration between the MSCC and GSCC, allows researchers to understand the operation of these bistable MIMs in a device setting and apply them toward the construction of artificial molecular machines. The three biggest influences on the ground-state rate constants arise from

  9. Click-PEGylation - A mobility shift approach to assess the redox state of cysteines in candidate proteins.

    PubMed

    van Leeuwen, Lucie A G; Hinchy, Elizabeth C; Murphy, Michael P; Robb, Ellen L; Cochemé, Helena M

    2017-07-01

    The redox state of cysteine thiols is critical for protein function. Whereas cysteines play an important role in the maintenance of protein structure through the formation of internal disulfides, their nucleophilic thiol groups can become oxidatively modified in response to diverse redox challenges and thereby function in signalling and antioxidant defences. These oxidative modifications occur in response to a range of agents and stimuli, and can lead to the existence of multiple redox states for a given protein. To assess the role(s) of a protein in redox signalling and antioxidant defence, it is thus vital to be able to assess which of the multiple thiol redox states are present and to investigate how these alter under different conditions. While this can be done by a range of mass spectrometric-based methods, these are time-consuming, costly, and best suited to study abundant proteins or to perform an unbiased proteomic screen. One approach that can facilitate a targeted assessment of candidate proteins, as well as proteins that are low in abundance or proteomically challenging, is by electrophoretic mobility shift assays. Redox-modified cysteine residues are selectively tagged with a large group, such as a polyethylene glycol (PEG) polymer, and then the proteins are separated by electrophoresis followed by immunoblotting, which allows the inference of redox changes based on band shifts. However, the applicability of this method has been impaired by the difficulty of cleanly modifying protein thiols by large PEG reagents. To establish a more robust method for redox-selective PEGylation, we have utilised a Click chemistry approach, where free thiol groups are first labelled with a reagent modified to contain an alkyne moiety, which is subsequently Click-reacted with a PEG molecule containing a complementary azide function. This strategy can be adapted to study reversibly reduced or oxidised cysteines. Separation of the thiol labelling step from the PEG

  10. N-acetylcysteine protects mice from lethal endotoxemia by regulating the redox state of immune cells.

    PubMed

    Victor, Victor M; Rocha, Milagros; De la Fuente, Monica

    2003-09-01

    The excessive production of reactive oxygen species (ROS) associated with inflammation leads to oxidative stress, which is involved with the high mortality from several diseases such as endotoxic shock and can be controlled to a certain degree by antioxidants. The immune cells use ROS in order to support their functions and, therefore, need adequate levels of antioxidant defenses in order to avoid the harmful effect of an excessive ROS production. In the present work, the effect of the administration of the antioxidant N-acetylcysteine (NAC) on the redox state of peritoneal macrophages and lymphocytes from mice with lethal endotoxic shock (100 mg/kg i.p. of lipopolysaccharide, LPS), was studied. In both types of immune cells at 0, 2, 4, 12 and 24 h after LPS injection, an increase of ROS, of the proinflammatory cytokine tumor necrosis factor alpha (TNFalpha), the lipid peroxidation (malonaldehyde levels, MDA), inducible nitric oxide synthase (iNOS) expression and the oxidized/reduced glutathione (GSSG/GSH) ratio, as well as a decrease of enzymatic antioxidant defenses, such as superoxide dismutase (SOD) and catalase (CAT) activity, was observed. The injection of NAC (150 mg/kg i.p. at 30 min after LPS injection) decreased the ROS, the TNFalpha the MDA levels, iNOS expression and the GSSG/GSH ratio, and increased the antioxidant defenses in both macrophages and lymphocytes. Moreover, the NAC treatment prevented the activation of nuclear translocation of the nuclear factor kappaB (NF-kappaB), which regulates ROS, inflammatory cytokines and antioxidant levels. Our present results provide evidence that both cell types have a relevant role in the pathogenesis of endotoxic shock, and that NAC, by improving the redox state of these immune cells, could increase mouse survival. Thus, antioxidants could offer an alternative treatment of human endotoxic shock.

  11. Assessing sulfur redox state and distribution in abyssal serpentinites using XANES spectroscopy

    NASA Astrophysics Data System (ADS)

    Debret, Baptiste; Andreani, Muriel; Delacour, Adélie; Rouméjon, Stéphane; Trcera, Nicolas; Williams, Helen

    2017-05-01

    Sulfur is one of the main redox sensitive and volatile elements involved in chemical transfers between earth surface and the deep mantle. At mid-oceanic ridges, sulfur cycle is highly influenced by serpentinite formation which acts as a sink of sulfur under various oxidation states (S2-, S-, S0 and S6+). Sulfur sequestration in serpentinites is usually attributed to the crystallization of secondary minerals, such as sulfides (e.g. pyrite, pyrrhotite) or sulfates (e.g. anhydrite). However, the role of serpentine minerals as potential sulfur carriers is not constrained. We investigate the distribution and redox state of sulfur at micro-scale combining in situ spectroscopic (X-ray absorption near-edge structure: XANES) and geochemical (SIMS) measurements in abyssal serpentinites from the SWIR (South West Indian Ridge), the Rainbow and the MARK (Mid-Atlantic Ridge, Kane Fracture Zone) areas. These serpentinites are formed in different tectono-metamorphic settings and provide a meaningful database to understand the fate of sulfur during seafloor serpentinization. XANES spectra of serpentinite powders show that the sulfur budget of the studied samples is dominated by oxidized sulfur (S6+ / ∑ S = 0.6- 1) although sulfate micro-phases, such as barite and anhydrite, are absent. Indeed, μ-XANES analyses of mesh, bastite and antigorite veins in thin sections and of serpentine grains rather suggest the presence of S6+ ions incorporated into serpentine minerals. The structural incorporation of S in serpentine minerals is also supported by X-ray fluorescence mapping revealing large areas (1600 μm2) of serpentinite where S is homogeneously distributed. Our observations show that serpentine minerals can incorporate high S concentrations, from 140 to 1350 ppm, and that this can account for 60 to 100% of the sulfur budget of abyssal serpentinites. Serpentine minerals thus play an important role in S exchanges between the hydrosphere and the mantle at mid-oceanic ridges and may

  12. Cycling State that Can Lead to Glassy Dynamics in Intracellular Transport

    NASA Astrophysics Data System (ADS)

    Scholz, Monika; Burov, Stanislav; Weirich, Kimberly L.; Scholz, Björn J.; Tabei, S. M. Ali; Gardel, Margaret L.; Dinner, Aaron R.

    2016-01-01

    Power-law dwell times have been observed for molecular motors in living cells, but the origins of these trapped states are not known. We introduce a minimal model of motors moving on a two-dimensional network of filaments, and simulations of its dynamics exhibit statistics comparable to those observed experimentally. Analysis of the model trajectories, as well as experimental particle tracking data, reveals a state in which motors cycle unproductively at junctions of three or more filaments. We formulate a master equation for these junction dynamics and show that the time required to escape from this vortexlike state can account for the power-law dwell times. We identify trends in the dynamics with the motor valency for further experimental validation. We demonstrate that these trends exist in individual trajectories of myosin II on an actin network. We discuss how cells could regulate intracellular transport and, in turn, biological function by controlling their cytoskeletal network structures locally.

  13. A cycling state that can lead to glassy dynamics in intracellular transport

    NASA Astrophysics Data System (ADS)

    Scholz, Monika; Burov, Stanislav; Weirich, Kimberly L.; Scholz, Bjorn J.; Tabei, S. M. Ali; Gardel, Margaret L.; Dinner, Aaron

    Power-law dwell times have been observed for molecular motors in living cells, but the origins of these trapped states are not known. We introduce a minimal model of motors moving on a two- dimensional network of filaments, and simulations of its dynamics exhibit statistics comparable to those observed experimentally. Analysis of the model trajectories, as well as experimental particle tracking data, reveals a state in which motors cycle unproductively at junctions of three or more filaments. We formulate a master equation for these junction dynamics and show that the time required to escape from this vortex-like state can account for the power-law dwell times. We identify trends in the dynamics with the motor valency for further experimental validation. We demonstrate that these trends exist in individual trajectories of myosin II on an actin network. We discuss how cells could regulate intracellular transport and, in turn, biological function, by controlling their cytoskeletal network structures locally.

  14. The influence of HMF and furfural on redox-balance and energy-state of xylose-utilizing Saccharomyces cerevisiae

    PubMed Central

    2013-01-01

    Background Pretreatment of biomass for lignocellulosic ethanol production generates compounds that can inhibit microbial metabolism. The furan aldehydes hydroxymethylfurfural (HMF) and furfural have received increasing attention recently. In the present study, the effects of HMF and furfural on redox metabolism, energy metabolism and gene expression were investigated in anaerobic chemostats where the inhibitors were added to the feed-medium. Results By cultivating the xylose-utilizing Saccharomyces cerevisiae strain VTT C-10883 in the presence of HMF and furfural, it was found that the intracellular concentrations of the redox co-factors and the catabolic and anabolic reduction charges were significantly lower in the presence of furan aldehydes than in cultivations without inhibitors. The catabolic reduction charge decreased from 0.13(±0.005) to 0.08(±0.002) and the anabolic reduction charge decreased from 0.46(±0.11) to 0.27(±0.02) when HMF and furfural were present. The intracellular ATP concentration was lower when inhibitors were added, but resulted only in a modest decrease in the energy charge from 0.87(±0.002) to 0.85(±0.004) compared to the control. Transcriptome profiling followed by MIPS functional enrichment analysis of up-regulated genes revealed that the functional group “Cell rescue, defense and virulence” was over-represented when inhibitors were present compared to control cultivations. Among these, the ATP-binding efflux pumps PDR5 and YOR1 were identified as important for inhibitor efflux and possibly a reason for the lower intracellular ATP concentration in stressed cells. It was also found that genes involved in pseudohyphal growth were among the most up-regulated when inhibitors were present in the feed-medium suggesting nitrogen starvation. Genes involved in amino acid metabolism, glyoxylate cycle, electron transport and amino acid transport were enriched in the down-regulated gene set in response to HMF and furfural. It was

  15. The influence of HMF and furfural on redox-balance and energy-state of xylose-utilizing Saccharomyces cerevisiae.

    PubMed

    Ask, Magnus; Bettiga, Maurizio; Mapelli, Valeria; Olsson, Lisbeth

    2013-02-15

    Pretreatment of biomass for lignocellulosic ethanol production generates compounds that can inhibit microbial metabolism. The furan aldehydes hydroxymethylfurfural (HMF) and furfural have received increasing attention recently. In the present study, the effects of HMF and furfural on redox metabolism, energy metabolism and gene expression were investigated in anaerobic chemostats where the inhibitors were added to the feed-medium. By cultivating the xylose-utilizing Saccharomyces cerevisiae strain VTT C-10883 in the presence of HMF and furfural, it was found that the intracellular concentrations of the redox co-factors and the catabolic and anabolic reduction charges were significantly lower in the presence of furan aldehydes than in cultivations without inhibitors. The catabolic reduction charge decreased from 0.13(±0.005) to 0.08(±0.002) and the anabolic reduction charge decreased from 0.46(±0.11) to 0.27(±0.02) when HMF and furfural were present. The intracellular ATP concentration was lower when inhibitors were added, but resulted only in a modest decrease in the energy charge from 0.87(±0.002) to 0.85(±0.004) compared to the control. Transcriptome profiling followed by MIPS functional enrichment analysis of up-regulated genes revealed that the functional group "Cell rescue, defense and virulence" was over-represented when inhibitors were present compared to control cultivations. Among these, the ATP-binding efflux pumps PDR5 and YOR1 were identified as important for inhibitor efflux and possibly a reason for the lower intracellular ATP concentration in stressed cells. It was also found that genes involved in pseudohyphal growth were among the most up-regulated when inhibitors were present in the feed-medium suggesting nitrogen starvation. Genes involved in amino acid metabolism, glyoxylate cycle, electron transport and amino acid transport were enriched in the down-regulated gene set in response to HMF and furfural. It was hypothesized that the HMF and

  16. Co-variation of nitrogen isotopes and redox states through glacial-interglacial cycles in the Black Sea

    NASA Astrophysics Data System (ADS)

    Quan, Tracy M.; Wright, James D.; Falkowski, Paul G.

    2013-07-01

    In all aquatic environments, nitrogen cycling within the water column is strongly influenced by oxygen. We hypothesize that the nitrogen isotopic composition (δ15N) of organic matter deposited in the sediments is a proxy for the redox state of the water column at the time of deposition. We tested the hypothesis by measuring the bulk sedimentary δ15N values in a drill core from the Black Sea, a basin that alternates between oxic, less saline conditions and anoxic, marine conditions on glacial-interglacial time scales. We reconstructed these changes in Black Sea redox conditions using sedimentary δ15N, total organic carbon (TOC), total nitrogen (TN), redox-sensitive metals, and micropaleontological data from a deep-sea core (DSDP Site 380). The sedimentary data reveal that during the transitions between oxic and anoxic conditions, δ15N values increased relative to the preceding and succeeding quasi-steady-state oxic and anoxic periods. The results indicate that the reciprocal transitional states from anoxic to oxic conditions were accompanied by intense denitrification; during the quasi-stable oxic and anoxic states (characterized by glacial fresh water and interglacial marine conditions) nitrification and complete nitrate utilization, respectively, dominate the nitrogen cycle. While other factors may influence the δ15N record, our results support the hypothesis that the variations in nitrogen isotopic composition of organic matter are strongly influenced by changes in redox state in the Black Sea subphotic zone on glacial-interglacial time scales, and can be explained by a relatively simple model describing the effects of oxygen on the microbial processes that drive the nitrogen cycle in marine ecosystems. Our model suggests that the nitrogen isotopic composition of marine sediments, on geological time scales, can be used to reconstruct the redox state of the overlying water column.

  17. Multiparametric protocol for the determination of thiol redox state in living matter.

    PubMed

    Grintzalis, Konstantinos; Papapostolou, Ioannis; Zisimopoulos, Dimitris; Stamatiou, Irene; Georgiou, Christos D

    2014-09-01

    Thiol redox state (TRS) evaluation is mostly restricted to the estimation of GSH and GSSG. However, these TRS parameters can estimate the GSSG/GSH potential, which might be useful for indicating abnormalities in redox metabolism. Nonetheless, evaluation of the multiparameric nature of TRS is required for a more accurate assessment of its physiological role. The present protocol extends the partial assessment of TRS by current methodologies. It measures 15 key parameters of TRS by two modular subprotocols: one for the glutathione (GSH)- and cysteine (CSH)-based nonprotein (NP) thiols/mixed disulfides (i.e., GSH, GSSG, GSSNP, CSH, CSSNP, NPSH, NPSSNP, NP(x)SH(NPSSNP), NP(x)SH(NPSH)), and the other for their protein (P) thiols/mixed disulfides (i.e., PSH, PSSG, PSSC, PSSNP, PSSP, NP(x)SH(PSSNP)). The protocol eliminates autoxidation of GSH and CSH (and thus overestimation of GSSG and CSSNP). Its modularity allows the determination GSH and GSSG also by other published specific assays. The protocol uses three assays; two are based on the photometric reagents 4,4'-dithiopyridine (DTP) and ninhydrin (NHD), and the third on the fluorometric reagent o-phthaldialdehyde (OPT). The initial assays employing these reagents have been extensively modified and redesigned for increased specificity, sensitivity, and simplicity. TRS parameter values and their standard errors are estimated automatically by sets of Excel-adapted algebraic equations. Protocol sensitivity for NPSH, PSH, NPSSNP, PSSP, PSSNP, CSH, CSSNP, PSSC, NP(x)SH(NPSSNP), and NP(x)SH(NPSH) is 1 nmol -SH/CSH, for GSSNP 0.2 nmol, for GSH and GSSG 0.4 nmol, and for PSSG 0.6 nmol. The protocol was applied on human plasma, a sample of high clinical value, and can be also applied in any organism.

  18. Strategies to improve the functions and redox state of the immune system in aged subjects.

    PubMed

    De la Fuente, Monica; Cruces, Julia; Hernandez, Oskarina; Ortega, Eduardo

    2011-12-01

    The aging process is accompanied by an impairment of the physiological systems including the immune system. This system is an excellent indicator of health. We have also observed that several functions of the immune cells are good markers of biological age and predictors of longevity. In agreement with the oxidation-inflammation theory that we have proposed, the chronic oxidative stress that appears with age affects all cells and especially those of the regulatory systems, such as the nervous, endocrine and immune systems and the communication between them. This fact prevents an adequate homeostasis and, therefore, the preservation of health. We have also proposed an involvement of the immune system in the aging process of the organism, concretely in the rate of aging, since there is a relation between the redox state and functional capacity of the immune cells and the longevity of individuals. A confirmation of the central role of the immune system in oxi-inflamm-aging is that several lifestyle strategies such as the administration of adequate amounts of antioxidants in the diet, physical exercise, physical and mental activity through environmental enrichment and hormetic interventions improve functions of immune cells, decreasing their oxidative stress, and consequently increasing the longevity of individuals. Recent results in mice of investigations on the effects of a new environmental enrichment (bathing in waters) as well as a hormetic intervention with slight infections (caused by injection of E.coli lipopolysaccharide, LPS), on several functions and redox parameters are shown. The advantages and possible problems of the use of those interventions to achieve a healthy aging and longevity are discussed.

  19. Obesity-Associated Oxidative Stress: Strategies Finalized to Improve Redox State

    PubMed Central

    Savini, Isabella; Catani, Maria Valeria; Evangelista, Daniela; Gasperi, Valeria; Avigliano, Luciana

    2013-01-01

    Obesity represents a major risk factor for a plethora of severe diseases, including diabetes, cardiovascular disease, non-alcoholic fatty liver disease, and cancer. It is often accompanied by an increased risk of mortality and, in the case of non-fatal health problems, the quality of life is impaired because of associated conditions, including sleep apnea, respiratory problems, osteoarthritis, and infertility. Recent evidence suggests that oxidative stress may be the mechanistic link between obesity and related complications. In obese patients, antioxidant defenses are lower than normal weight counterparts and their levels inversely correlate with central adiposity; obesity is also characterized by enhanced levels of reactive oxygen or nitrogen species. Inadequacy of antioxidant defenses probably relies on different factors: obese individuals may have a lower intake of antioxidant- and phytochemical-rich foods, such as fruits, vegetables, and legumes; otherwise, consumption of antioxidant nutrients is normal, but obese individuals may have an increased utilization of these molecules, likewise to that reported in diabetic patients and smokers. Also inadequate physical activity may account for a decreased antioxidant state. In this review, we describe current concepts in the meaning of obesity as a state of chronic oxidative stress and the potential interventions to improve redox balance. PMID:23698776

  20. Mapping of redox state of mitochondrial cytochromes in live cardiomyocytes using Raman microspectroscopy.

    PubMed

    Brazhe, Nadezda A; Treiman, Marek; Brazhe, Alexey R; Find, Ninett L; Maksimov, Georgy V; Sosnovtseva, Olga V

    2012-01-01

    This paper presents a nonivasive approach to study redox state of reduced cytochromes c, c1 and b of complexes II and III in mitochondria of live cardiomyocytes by means of Raman microspectroscopy. For the first time with the proposed approach we perform studies of rod- and round-shaped cardiomyocytes, representing different morphological and functional states. Raman mapping and cluster analysis reveal that these cardiomyocytes differ in the amounts of reduced cytochromes c, c1 and b. The rod-shaped cardiomyocytes possess uneven distribution of reduced cytochromes c, c1 and b in cell center and periphery. Moreover, by means of Raman spectroscopy we demonstrated the decrease in the relative amounts of reduced cytochromes c, c1 and b in the rod-shaped cardiomyocytes caused by H2O2-induced oxidative stress before any visible changes. Results of Raman mapping and time-dependent study of reduced cytochromes of complexes II and III and cytochrome c in cardiomyocytes are in a good agreement with our fluorescence indicator studies and other published data.

  1. Redox and metal-regulated oligomeric state for human porphobilinogen synthase activation.

    PubMed

    Sawada, N; Nagahara, N; Arisaka, F; Mitsuoka, K; Minami, M

    2011-06-01

    The oligomeric state of human porphobilinogen synthase (PBGS) [EC.4.2.1.24] is homooctamer, which consists of conformationally heterogenous subunits in the tertiary structure under air-saturated conditions. When PBGS is activated by reducing agent with zinc ion, a reservoir zinc ion coordinated by Cys(223) is transferred in the active center to be coordinated by Cys(122), Cys(124), and Cys(132) (Sawada et al. in J Biol Inorg Chem 10:199-207, 2005). The latter zinc ion serves as an electrophilic catalysis. In this study, we investigated a conformational change associated with the PBGS activation by reducing agent and zinc ion using analytical ultracentrifugation, negative staining electron microscopy, native PAGE, and enzyme activity staining. The results are in good agreement with our notion that the main component of PBGS is octamer with a few percent of hexamer and that the octamer changes spatial subunit arrangement upon reduction and further addition of zinc ion, accompanying decrease in f/f (0). It is concluded that redox-regulated PBGS activation via cleavage of disulfide bonds among Cys(122), Cys(124), and Cys(132) and coordination with zinc ion is closely linked to change in the oligomeric state.

  2. Hyperoxia, mitochondrial redox state, and lactate metabolism of in situ canine muscle.

    PubMed

    Wolfe, B R; Graham, T E; Barclay, J K

    1987-08-01

    The effect of hyperoxia on lactate production and release and the mitochondrial NAD+-to-NADH ratio was studied in the in situ canine gastrocnemius to determine whether elevated PO2 altered metabolic regulation. Dogs breathed either air (21% O2) [arterial O2 partial pressure (PaO2) 90 mmHg; n = 8] or hyperoxia (100% O2) (PaO2 546 mmHg; n = 8). The left muscle was stimulated for 10 min at 3 Hz and then both right and left muscles were quick frozen in N2. Hyperoxia did not affect O2 uptake, blood flow, and developed tension. Activity increased glucose 6-phosphate (G-6-P), D-fructose 6-phosphate (F-6-P), NH3, lactate, and F-6-P/F-1,6-P in both treatment groups. No significant differences in arterial or venous lactate, muscle lactate, glucose uptake, or glycogen depletion were noted in hyperoxia. Cytoplasmic NAD+/NADH was in a more oxidized state in hyperoxia at rest but not during activity. The increase in NH3 with stimulation was significantly larger in hyperoxia. Activity decreased alpha-ketoglutarate in hyperoxia but not in air. At stimulation, the estimated mitochondrial NAD+/NADH increased in both groups suggesting that hypoxia was not present. Thus hyperoxia did not affect mitochondrial redox state or lactate production and release in active muscle.

  3. Formation of ferromanganese crust in Western Pacific Magellan Seamount: Variations in redox state of Fe/Mn

    NASA Astrophysics Data System (ADS)

    Yang, K.; Park, H.; Kim, J. W.; Baik, H.; Kim, J.; Park, K. R.; Yoon, J.

    2016-02-01

    Redox reaction is a ubiquitous process in the formation of ferromanganese crust that may reflect one of paleoenvironments, particularly variations of Fe/Mn redox states and microbial diversity in the crust suggests the unique biogeochemical reactions when the crust formed in the ocean sediment. Samples were dredged from the seamounts in the western Pacific Magellan Seamount (OSM11) to investigate the biotic/abiotic redox reaction in the formation of the crust that consists of five well-defined layers from the rim (layer 1) to the core (layer 5). Mineralogy, morphology and Fe/Mn oxidation state in each layer were determined by X-ray Diffractometer (XRD), Transmission Electron Microscopy (TEM), Selected Area Electron Diffraction (SAED) pattern, Energy Dispersive X-ray spectrometer (EDX), and Electron Energy Loss Spectroscopy (EELS). Fe-rich vernadite was detected in all layers while quartz, feldspar, and hematite only appeared in layer 1, and carbonate fluorapatite (CFA) were observed in layers 4 and 5. The oxidation states of Fe in Fe-rich vernadite measured by EELS showed a distinct change between layers ranging 26 - 60 % of Fe3+/Fetot. Analyses of Restriction Fragment Length Polymorphism (RFLP) indicated the presence of functional gene (CumA) association with Mn oxidizer suggesting that the biotic Mn oxidation may promote the formation of the Fe-Mn crust. The present study collectively showed a process of ferromanganese crust formation, secondary phase mineral precipitation such as CFA, and a distinct changes in Fe-redox states implying the biotic/abiotic associations such as biotic local reduction of Fe or uplift-subsidence of sea mounts, inducing the variations redox conditions in the formation of the crust.

  4. Effects of geodynamic setting on the redox state of fluids released by subducted mantle lithosphere

    NASA Astrophysics Data System (ADS)

    Evans, K. A.; Reddy, S. M.; Tomkins, A. G.; Crossley, R. J.; Frost, B. R.

    2017-05-01

    Magnetite breakdown during subduction of serpentinised ultramafic rocks may produce oxidised fluids that oxidise the deep Earth and/or the sub-arc mantle, either via direct transport of ferric iron, or via redox reactions between ferric iron and other elements, such as sulfur. However, so far, there is no consensus on the oxidation state of fluids released during subduction of ultramafic rocks, or the factors that control this oxidation state. Subducted samples from a magma-poor rifted margin and a supra-subduction zone geodynamic setting were compared to examine evidence of changes in opaque phase assemblage and ferric iron content as a consequence of subduction, and as a function of geodynamic setting. Thermodynamic calculations in the system Fe-Ni-O-H-S and Fe-Ni-O-S at the pressures and temperatures of interest were used to constrain oxygen activities and fluid compositions. Samples from New Caledonia, which exemplify supra-subduction zone mantle, contain awaruite (FeNi3) and equilibrated with hydrogen-bearing fluids at oxygen activity less than the FMQ (fayalite-magnetite-quartz) buffer. In contrast, samples from the Zermatt Saas Zone ophiolite, Western Alps, which are thought to represent mantle from a subducted magma-poor rifted margin, contain magnetite plus sulfur-rich phases such as pyrite (FeS2), and are inferred to have equilibrated with hydrogen-poor fluids at oxygen activity greater than FMQ. This major difference is independent of differences in subduction pressure-temperature conditions, variation in peridotite protolith composition, or the nature of adjacent units. We propose that the Zermatt Saas Zone samples would have undergone more complete serpentinisation prior to subduction than the supra-subduction zone (SSZ) New Caledonian samples. This difference explains the different fluid compositions, because incompletely serpentinised rocks containing olivine and brucite retain or evolve awaruite-bearing assemblages that buffer fluid compositions to

  5. Redox State of Iron in Lunar Glasses using X-ray Absorption Spectroscopy and Multivariate Analysis

    NASA Astrophysics Data System (ADS)

    Dyar, M. D.; McCanta, M. C.; Lanzirotti, A.; Sutton, S. R.; Carey, C. J.; Mahadevan, S.; Rutherford, M. J.

    2014-12-01

    The oxidation state of igneous materials on a planet is a critically-important variable in understanding magma evolution on bodies in our solar system. However, direct and indirect methods for quantifying redox states are challenging, especially across the broad spectrum of silicate glass compositions found on airless bodies. On the Moon, early Mössbauer studies of bulk samples suggested the presence of significant Fe3+ (>10%) in lunar glasses (green, orange, brown); lunar analog glasses synthesized at fO2 <10-11 have similar Fe3+. All these Mössbauer spectra are challenging to interpret due to the presence of multiple coordination environments in the glasses. X-ray absorption spectroscopy (XAS) allows pico- and nano-scale interrogation of primitive planetary materials using the pre-edge, main edge, and EXAFS regions of absorption edge spectra. Current uses of XAS require availability of standards with compositions similar to those of unknowns and complex procedures for curve-fitting of pre-edge features that produce results with poorly constrained accuracy. A new approach to accurate and quantitative redox measurements with XAS is to couple use of spectra from synthetic glass standards covering a broad compositional range with multivariate analysis (MVA) techniques. Mössbauer and XAS spectra from a suite of 33 synthetic glass standards covering a wide range of compositions and fO2(Dyar et al., this meeting) were used to develop a MVA model that utilizes valuable predictive information not only in the major spectral peaks/features, but in all channels of the XAS region. Algorithms for multivariate analysis t were used to "learn" the characteristics of a data set as a function of varying spectral characteristics. These models were applied to the study of lunar glasses, which provide a challenging test case for these newly-developed techniques due to their very low fO2. Application of the new XAS calibration model to Apollo 15 green (15426, 15427 and 15425

  6. A Protocol for Electrochemical Evaluations and State of Charge Diagnostics of a Symmetric Organic Redox Flow Battery.

    PubMed

    Duan, Wentao; Vemuri, Rama S; Hu, Dehong; Yang, Zheng; Wei, Xiaoliang

    2017-02-13

    Redox flow batteries have been considered as one of the most promising stationary energy storage solutions for improving the reliability of the power grid and deployment of renewable energy technologies. Among the many flow battery chemistries, non-aqueous flow batteries have the potential to achieve high energy density because of the broad voltage windows of non-aqueous electrolytes. However, significant technical hurdles exist currently limiting non-aqueous flow batteries to demonstrate their full potential, such as low redox concentrations, low operating currents, under-explored battery status monitoring, etc. In an attempt to address these limitations, we recently reported a non-aqueous flow battery based on a highly soluble, redox-active organic nitronyl nitroxide radical compound, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO). This redox material exhibits an ambipolar electrochemical property, and therefore can serve as both anolyte and catholyte redox materials to form a symmetric flow battery chemistry. Moreover, we demonstrated that Fourier transform infrared (FTIR) spectroscopy could measure the PTIO concentrations during the PTIO flow battery cycling and offer reasonably accurate detection of the battery state of charge (SOC), as cross-validated by electron spin resonance (ESR) measurements. Herein we present a video protocol for the electrochemical evaluation and SOC diagnosis of the PTIO symmetric flow battery. With a detailed description, we experimentally demonstrated the route to achieve such purposes. This protocol aims to spark more interests and insights on the safety and reliability in the field of non-aqueous redox flow batteries.

  7. Potential regulation of gene expression in photosynthetic cells by redox and energy state: approaches towards better understanding.

    PubMed

    Pfannschmidt, T; Bräutigam, K; Wagner, R; Dietzel, L; Schröter, Y; Steiner, S; Nykytenko, A

    2009-02-01

    Photosynthetic electron transport is performed by a chain of redox components that are electrochemically connected in series. Its efficiency depends on the balanced action of the photosystems and on the interaction with the dark reaction. Plants are sessile and cannot escape from environmental conditions such as fluctuating illumination, limitation of CO(2) fixation by low temperatures, salinity, or low nutrient or water availability, which disturb the homeostasis of the photosynthetic process. Photosynthetic organisms, therefore, have developed various molecular acclimation mechanisms that maintain or restore photosynthetic efficiency under adverse conditions and counteract abiotic stresses. Recent studies indicate that redox signals from photosynthetic electron transport and reactive oxygen species (ROS) or ROS-scavenging molecules play a central role in the regulation of acclimation and stress responses. The underlying signalling network of photosynthetic redox control is largely unknown, but it is already apparent that gene regulation by redox signals is of major importance for plants. Signalling cascades controlling the expression of chloroplast and nuclear genes have been identified and dissection of the different pathways is advancing. Because of the direction of information flow, photosynthetic redox signals can be defined as a distinct class of retrograde signals in addition to signals from organellar gene expression or pigment biosynthesis. They represent a vital signal of mature chloroplasts that report their present functional state to the nucleus. Here we describe possible problems in the elucidation of redox signalling networks and discuss some aspects of plant cell biology that are important for developing suitable experimental approaches. The photosynthetic function of chloroplasts represents an important sensor that integrates various abiotic changes in the environment into corresponding molecular signals, which, in turn, regulate cellular

  8. A symmetric organic-based nonaqueous redox flow battery and its state of charge diagnostics by FTIR

    DOE PAGES

    Duan, Wentao; Vemuri, Rama Ses; Milshtein, Jarrod D.; ...

    2016-03-10

    Redox flow batteries have shown outstanding promise for grid-scale energy storage to promote utilization of renewable energy and improve grid stability. Nonaqueous battery systems can potentially achieve high energy density because of their broad voltage window. In this paper, we report a new organic redox-active material for use in a nonaqueous redox flow battery, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO) that has high solubility (>2.6 M) in organic solvents. PTIO exhibits electrochemically reversible disproportionation reactions and thus can serve as both anolyte and catholyte redox materials in a symmetric flow cell. The PTIO flow battery has a moderate cell voltage of ~1.7 V andmore » shows good cyclability under both cyclic voltammetry and flow cell conditions. Moreover, we demonstrate that FTIR can offer accurate estimation of the PTIO concentration in electrolytes and determine the state of charge of the PTIO flow cell, which suggests FTIR potentially as a powerful online battery status sensor. In conclusion, this study is expected to inspire more insights in this under-addressed area of state of charge analysis aiming at operational safety and reliability of flow batteries.« less

  9. A symmetric organic-based nonaqueous redox flow battery and its state of charge diagnostics by FTIR

    SciTech Connect

    Duan, Wentao; Vemuri, Rama Ses; Milshtein, Jarrod D.; Laramie, Sydney; Dmello, Rylan D.; Huang, Jinhua; Zhang, Lu; Hu, Dehong; Vijayakumar, M.; Wang, Wei; Liu, Jun; Darling, Robert E.; Thompson, Levi; Smith, Kyle C.; Moore, Jeffrey S.; Brushett, Fikile; Wei, Xiaoliang

    2016-03-10

    Redox flow batteries have shown outstanding promise for grid-scale energy storage to promote utilization of renewable energy and improve grid stability. Nonaqueous battery systems can potentially achieve high energy density because of their broad voltage window. In this paper, we report a new organic redox-active material for use in a nonaqueous redox flow battery, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO) that has high solubility (>2.6 M) in organic solvents. PTIO exhibits electrochemically reversible disproportionation reactions and thus can serve as both anolyte and catholyte redox materials in a symmetric flow cell. The PTIO flow battery has a moderate cell voltage of ~1.7 V and shows good cyclability under both cyclic voltammetry and flow cell conditions. Moreover, we demonstrate that FTIR can offer accurate estimation of the PTIO concentration in electrolytes and determine the state of charge of the PTIO flow cell, which suggests FTIR potentially as a powerful online battery status sensor. In conclusion, this study is expected to inspire more insights in this under-addressed area of state of charge analysis aiming at operational safety and reliability of flow batteries.

  10. Modeling the Time-dependent Changes in Electrical Conductivity of Basaltic Melts With Redox State

    NASA Astrophysics Data System (ADS)

    Pommier, A.; Gaillard, F.; Pichavant, M.

    2008-12-01

    The electrical conductivity σ is an efficient probe of mass transfer processes within silicate melts and magmas. Little attention has been given to the influence of redox state (fO2) on the melts conductivity. We present an experimental setup allowing electrical conductivity measurements for basaltic melts under variable fO2. We demonstrate a significant dependence of σ with fO2, allowing to characterize in situ the mechanisms and kinetics of redox changes in the melt. Experiments were conducted on basalts from Pu'u 'O'o, Hawaii, and Mt.Vesuvius, Italy. Measurements were performed cylindrical glass samples (OD: 6mm, ID: 1mm, L: 8mm) using an impedance spectrometer. Experiments were conducted in a 1atm vertical furnace, from 1200°C to 1400°C. Variable gas atmosphere (air, CO2 or CO-CO2 gas mixtures) were used, imposing ΔNNO from -1 to +7. Electrical conductivities were determined for the two melts at constant fO2, different T (constant fO2) and constant T, different fO2 (variable fO2) obtained by changing the gas composition. Isothermal reduction and oxidation cycles were performed. Glasses quenched from different T and fO2 conditions were analyzed by electron microprobe, the FeO concentration was determined by wet chemistry. In constant fO2 experiments, a small but detectable effect of fO2 on σ is evidenced. At 1300°C, the difference in the Kilauea sample conductivity between reduced (ΔNNO=-1) and oxidized (ΔNNO=+7) fO2 is <1(ohm.m)-1, the sample being more conductive when reduced. The temperature dependence of σ was fitted using Arrhenian equations, the activation energy Ea being 100kJ/mol. Sodium was identified as the main charge carrier in the melts. The fO2-effect on σ can thus be attributed to the influence of the Fe2+/Fe3+ ratio on sodium mobility. The fO2-dependence of σ was included in the model of Pommier et al.(2008), allowing the conductivity of natural melts to be calculated as a function of T, P, H2O, and fO2. Variable fO2 experiments

  11. High Light Acclimation in the Secondary Plastids Containing Diatom Phaeodactylum tricornutum is Triggered by the Redox State of the Plastoquinone Pool1[W][OA

    PubMed Central

    Lepetit, Bernard; Sturm, Sabine; Rogato, Alessandra; Gruber, Ansgar; Sachse, Matthias; Falciatore, Angela; Kroth, Peter G.; Lavaud, Johann

    2013-01-01

    In diatoms, the process of energy-dependent chlorophyll fluorescence quenching (qE) has an important role in photoprotection. Three components are essential for qE: (1) the light-dependent generation of a transthylakoidal proton gradient; (2) the deepoxidation of the xanthophyll diadinoxanthin (Dd) into diatoxanthin (Dt); and (3) specific nucleus-encoded antenna proteins, called Light Harvesting Complex Protein X (LHCX). We used the model diatom Phaeodactylum tricornutum to investigate the concerted light acclimation response of the qE key components LHCX, proton gradient, and xanthophyll cycle pigments (Dd+Dt) and to identify the intracellular light-responsive trigger. At high-light exposure, the up-regulation of three of the LHCX genes and the de novo synthesis of Dd+Dt led to a pronounced rise of qE. By inhibiting either the conversion of Dd to Dt or the translation of LHCX genes, qE amplification was abolished and the diatom cells suffered from stronger photoinhibition. Artificial modification of the redox state of the plastoquinone (PQ) pool via 3-(3,4-dichlorophenyl)-1,1-dimethylurea and 5-dibromo-6-isopropyl-3-methyl-1,4-benzoquinone resulted in a disturbance of Dd+Dt synthesis in an opposite way. Moreover, we could increase the transcription of two of the four LHCX genes under low-light conditions by reducing the PQ pool using 5-dibromo-6-isopropyl-3-methyl-1,4-benzoquinone. Altogether, our results underline the central role of the redox state of the PQ pool in the light acclimation of diatoms. Additionally, they emphasize strong evidence for the existence of a plastid-to-nucleus retrograde signaling mechanism in an organism with plastids that derived from secondary endosymbiosis. PMID:23209128

  12. Effects of Protonation State on a Tyrosine-Histidine Bioinspired Redox Mediator

    SciTech Connect

    Moore, Gary F.; Hambourger, Michael; Kodis, Gerdenis; Michl, Weston; Gust, Devens; Moore, Thomas A.; Moore, Ana L.

    2010-11-18

    The conversion of tyrosine to the corresponding tyrosyl radical in photosytem II (PSII) is an example of proton-coupled electron transfer. Although the tyrosine moiety (TyrZ) is known to function as a redox mediator between the photo-oxidized primary donor (P680 •+) and the Mn-containing oxygen-evolving complex, the protonation states involved in the course of the reaction remain an active area of investigation. Herein, we report on the optical, structural, and electrochemical properties of tyrosine-histidine constructs, which model the function of their naturally occurring counterparts in PSII. Electrochemical studies show that the phenoxyl/phenol couple of the model is chemically reversible and thermodynamically capable of water oxidation. Studies under acidic and basic conditions provide clear evidence that an ionizable proton controls the electrochemical potential of the tyrosine-histidine mimic and that an exogenous base or acid can be used to generate a low-potential or high-potential mediator, respectively. The phenoxyl/phenoxide couple associated with the low-potential mediator is thermodynamically incapable of water oxidation, whereas the relay associated with the high-potential mediator is thermodynamically incapable of reducing an attached photoexcited porphyrin. These studies provide insight regarding the mechanistic role of the tyrosine-histidine complex in water oxidation and strategies for making use of hydrogen bonds to affect the coupling between proton and electron transfer in artificial photosynthetic systems.

  13. Cross-talk between the cellular redox state and the circadian system in Neurospora.

    PubMed

    Yoshida, Yusuke; Iigusa, Hideo; Wang, Niyan; Hasunuma, Kohji

    2011-01-01

    The circadian system is composed of a number of feedback loops, and multiple feedback loops in the form of oscillators help to maintain stable rhythms. The filamentous fungus Neurospora crassa exhibits a circadian rhythm during asexual spore formation (conidiation banding) and has a major feedback loop that includes the FREQUENCY (FRQ)/WHITE COLLAR (WC) -1 and -2 oscillator (FWO). A mutation in superoxide dismutase (sod)-1, an antioxidant gene, causes a robust and stable circadian rhythm compared with that of wild-type (Wt). However, the mechanisms underlying the functions of reactive oxygen species (ROS) remain unknown. Here, we show that cellular ROS concentrations change in a circadian manner (ROS oscillation), and the amplitudes of ROS oscillation increase with each cycle and then become steady (ROS homeostasis). The ROS oscillation and homeostasis are produced by the ROS-destroying catalases (CATs) and ROS-generating NADPH oxidase (NOX). cat-1 is also induced by illumination, and it reduces ROS levels. Although ROS oscillation persists in the absence of frq, wc-1 or wc-2, its homeostasis is altered. Furthermore, genetic and biochemical evidence reveals that ROS concentration regulates the transcriptional function of WCC and a higher ROS concentration enhances conidiation banding. These findings suggest that the circadian system engages in cross-talk with the cellular redox state via ROS-regulatory factors.

  14. Changes in the redox state of sediments following the 2010 BP blowout

    NASA Astrophysics Data System (ADS)

    Hastings, D. W.; Brooks, G.; Hollander, D. J.; Larson, R. A.; Morford, J. L.; Romero, I.; Hammaker, S.; Hogan, A.; Roeder, T. K.

    2012-12-01

    We have collected multi-core sediment cores from over 40 sites along the NE Gulf of Mexico continental slope following the 2010 Deepwater Horizon oil spill. We present the geochemical results from four select sites collected on August 2010, December 2010, February 2011, September 2011, and August 2012. Cores were extruded at 2 mm intervals, and sediments were analyzed for TOC, 13C, carbonate, short-lived radioisotopes (Pb-210, Cs-137, Be-7, Th-234) and grain size. Cores reveal a well-defined, internally stratified dark brown layer in the top 1-6 cm, with finer grain size than underlying sediments. Samples were digested at high temperature and pressure in concentrated nitric acid to dissolve both the oil and authigenic fractions, but not the detrital component. Samples were subsequently analyzed by ICP-MS. Although the Macondo crude oil is slightly enriched in Ni, V, and Co, with concentrations of 2.8, 0.9, and 0.08ppm, respectively, no significant enrichment of these metals is observed in Gulf of Mexico sediments. Sediment mass accumulation rates following the event range from 0.6 - 20 g/cm2/yr, which are one to two orders of magnitude higher than pre-spill rates. Organic and inorganic carbon deposition rates from the 2010 and February 2011 cores are also elevated one to two orders of magnitude. 13C signatures of this recent deposited material are slightly depleted relative to pre-oil event material. Large sedimentation rates, depleted 13C values and lack of bioturbation on the surface of the deep sediments studied supports the hypothesis of a large sea-snow-like blizzard event during the oil-spill in 2010. Bacterially mediated oxidation of organic matter is reflected in a well-established sequence of oxidation-reduction reactions. We exploit redox sensitive trace elements including Mn, Fe, Re, U, Mo, and V to infer changes in the redox state of sediments following this large pulse of organic matter to the seafloor.

  15. The chemistry behind redox regulation with a focus on sulphur redox systems.

    PubMed

    Jacob, Claus; Anwar, Awais

    2008-07-01

    Sulphur metabolism in plants provides a wealth of natural products, including several chemically unusual substances, such as thiosulphinates, polysulphides and isothiocyanates. Many of these reactive sulphur species (RSS) exhibit a distinct redox behaviour in vitro, which translates into a rather interesting biological activity in vivo, such as antibiotic, fungicidal, pesticidal or anticancer activity. While the molecular basis for such activity has long remained obscure, research into sulphur-based redox systems during the past 5-10 years has achieved a better knowledge of the in vitro properties of RSS and has led to an improved understanding of their impact on intracellular redox signalling and control pathways in living cells. It has become apparent that the redox chameleon sulphur occurs in biological systems in about 10 different oxidation states, which give rise to an extensive and complicated network of sulphur-based redox events. Together, natural sulphur products from plants and their intracellular targets provide the basis for innovative design of novel antibiotics, fungicides, pesticides and anticancer agents.

  16. Star-shape redox-responsive PEG-sheddable copolymer of disulfide-linked polyethylene glycol-lysine-di-tocopherol succinate for tumor-triggering intracellular doxorubicin rapid release: head-to-head comparison.

    PubMed

    Ai, Xiaoyu; Sun, Jin; Zhong, Lu; Wu, Chunnuan; Niu, Handong; Xu, Tao; Lian, He; Han, Xiaopeng; Ren, Guolian; Ding, Wenya; Wang, Jia; Pu, Xiaohui; He, Zhonggui

    2014-10-01

    A redox-responsive poly(ethylene glycol) (PEG)-sheddable copolymer of disulfide-linked PEG 5000-lysine-di-tocopherol succinate (P(5k)SSLV) is developed which can self-assemble into nanomicelles in aqueous condition and trigger the rapid release of encapsulated drugs within tumor cells. The reduction-insensitive doxorubicin (DOX)-loaded P(5k)LV (P(5k)LV-DOX) nanomicelles are further prepared. Then head-to-head comparison of P(5k)SSLV-DOX, P(5k)LV-DOX and DOX-Sol is performed concerning in vitro release, cytotoxicity, cellular uptake and apoptosis. Results show that P(5k)SSLV-DOX nanomicelles have a faster DOX release, a higher anti-tumor activity and more DOX concentrating in the nucleus than P(5k)LV-DOX nanomicelles. In conclusion, the redox-responsive P(5k)SSLV nanomicelles might hold a great potential to improve chemotherapy by tumor-triggering intracellular rapid release. The outcomes of this study also address the significance of such head-to-head comparison studies in translational research of nanomedicine.

  17. Soluble oligomers of amyloid-β cause changes in redox state, DNA methylation, and gene transcription by inhibiting EAAT3 mediated cysteine uptake.

    PubMed

    Hodgson, Nathaniel; Trivedi, Malav; Muratore, Christina; Li, Shaomin; Deth, Richard

    2013-01-01

    Oxidative stress, hyperhomocysteinemia, altered DNA methylation, and insulin resistance in the brain are associated with Alzheimer's disease (AD), but the role of amyloid-β (Aβ) in these events remains unclear. Intracellular cysteine is rate-limiting for synthesis of the antioxidant glutathione (GSH), and factors regulating cysteine uptake exert a powerful influence over cellular redox status, especially in mature neurons where cysteine synthesis via transsulfuration of homocysteine (HCY) is restricted. We investigated the effect of soluble Aβ oligomers (oAβ) on basal and insulin-like growth factor-1 (IGF-1)-induced cysteine uptake mediated by the excitatory amino acid transporter 3 (EAAT3) in cultured human neuronal cells. We also examined the effect of oAβ on intracellular thiol metabolite levels, DNA methylation, and the transcription status of redox and methylation-associated genes. oAβ inhibited EAAT3-mediated cysteine uptake, causing a decrease in intracellular cysteine and GSH levels. The ratio of the methyl donor S-adenosylmethionine to the methylation inhibitor S-adenosylhomocysteine was decreased, in association with an increase in HCY and a global decrease in DNA methylation, indicative of decreased activity of the redox-sensitive enzyme methionine synthase. These metabolic effects of oAβ coincided with changes in the expression of redox and methylation pathway genes. The ability of oAβ to modulate gene expression via their redox and methylation-dependent epigenetic effects may contribute to the pathology of AD and recognition of this mechanism may lead to novel treatment approaches. We describe a role of IGF-1 signaling in regulating redox and methylation homeostasis, and propose this to be a pathogenic target of oAβ.

  18. Effect of ethanol on the redox state of the coenzyme bound to alcohol dehydrogenase studied in isolated hepatocytes.

    PubMed Central

    Cronholm, T

    1987-01-01

    Hepatocytes were isolated from fed female rats and incubated with a redox indicator system consisting of cyclohexanone and unlabelled or perdeuterated cyclohexanol. The concentrations and deuterium contents of these were measured by g.l.c. and g.l.c.-m.s. of oxime t-butyldimethylsilyl derivatives. The equilibrium composition represented the redox state of the coenzyme bound to alcohol dehydrogenase, since 4-methylpyrazole inhibited the interconversion. Reduction appeared to be catalysed to a small extent also by an NADPH-dependent aldehyde reductase. The NADH/NAD+ ratio on alcohol dehydrogenase was 3 orders of magnitude higher in the presence of ethanol than in its absence. This redox shift has the degree expected from reported kinetic constants. The shift was due both to a decreased rate of oxidation and to an increased rate of reduction in the indicator system. The results indicate that the redox effect of ethanol on the free NAD system is due to efficient removal of acetaldehyde from a near-equilibrium system consisting of ethanol, acetaldehyde and bound coenzymes, together with dissociation of NADH from the enzyme. The effect on the redox state of the bound coenzyme was less marked when the ethanol was deuterated at C-1, indicating an isotope effect. The 2H excess in the cyclohexanol formed was about 70% of that in the [1,1-2H2]ethanol. This dilution, which is caused by binding of free NADH to the enzyme, indicates that reoxidation of cytosolic NADH partly limits the rate of ethanol oxidation. PMID:3435467

  19. Proline Dehydrogenase Regulates Redox State and Respiratory Metabolism in Trypanosoma cruzi

    PubMed Central

    Paes, Lisvane Silva; Suárez Mantilla, Brian; Zimbres, Flávia Menezes; Pral, Elisabeth Mieko Furusho; Diogo de Melo, Patrícia; Tahara, Erich B.; Kowaltowski, Alicia J.; Elias, Maria Carolina; Silber, Ariel Mariano

    2013-01-01

    Over the past three decades, L-proline has become recognized as an important metabolite for trypanosomatids. It is involved in a number of key processes, including energy metabolism, resistance to oxidative and nutritional stress and osmoregulation. In addition, this amino acid supports critical parasite life cycle processes by acting as an energy source, thus enabling host-cell invasion by the parasite and subsequent parasite differentiation. In this paper, we demonstrate that L-proline is oxidized to Δ1-pyrroline-5-carboxylate (P5C) by the enzyme proline dehydrogenase (TcPRODH, E.C. 1.5.99.8) localized in Trypanosoma cruzi mitochondria. When expressed in its active form in Escherichia coli, TcPRODH exhibits a Km of 16.58±1.69 µM and a Vmax of 66±2 nmol/min mg. Furthermore, we demonstrate that TcPRODH is a FAD-dependent dimeric state protein. TcPRODH mRNA and protein expression are strongly upregulated in the intracellular epimastigote, a stage which requires an external supply of proline. In addition, when Saccharomyces cerevisiae null mutants for this gene (PUT1) were complemented with the TcPRODH gene, diminished free intracellular proline levels and an enhanced sensitivity to oxidative stress in comparison to the null mutant were observed, supporting the hypothesis that free proline accumulation constitutes a defense against oxidative imbalance. Finally, we show that proline oxidation increases cytochrome c oxidase activity in mitochondrial vesicles. Overall, these results demonstrate that TcPRODH is involved in proline-dependant cytoprotection during periods of oxidative imbalance and also shed light on the participation of proline in energy metabolism, which drives critical processes of the T. cruzi life cycle. PMID:23894476

  20. Redox signaling in plants.

    PubMed

    Foyer, Christine H; Noctor, Graham

    2013-06-01

    Our aim is to deliver an authoritative and challenging perspective of current concepts in plant redox signaling, focusing particularly on the complex interface between the redox and hormone-signaling pathways that allow precise control of plant growth and defense in response to metabolic triggers and environmental constraints and cues. Plants produce significant amounts of singlet oxygen and other reactive oxygen species (ROS) as a result of photosynthetic electron transport and metabolism. Such pathways contribute to the compartment-specific redox-regulated signaling systems in plant cells that convey information to the nucleus to regulate gene expression. Like the chloroplasts and mitochondria, the apoplast-cell wall compartment makes a significant contribution to the redox signaling network, but unlike these organelles, the apoplast has a low antioxidant-buffering capacity. The respective roles of ROS, low-molecular antioxidants, redox-active proteins, and antioxidant enzymes are considered in relation to the functions of plant hormones such as salicylic acid, jasmonic acid, and auxin, in the composite control of plant growth and defense. Regulation of redox gradients between key compartments in plant cells such as those across the plasma membrane facilitates flexible and multiple faceted opportunities for redox signaling that spans the intracellular and extracellular environments. In conclusion, plants are recognized as masters of the art of redox regulation that use oxidants and antioxidants as flexible integrators of signals from metabolism and the environment.

  1. Calibration of CCD-based redox imaging for biological tissues

    NASA Astrophysics Data System (ADS)

    Xu, He N.; Wu, Baohua; Nioka, Shoko; Chance, Britton; Li, Lin Z.

    2009-02-01

    Clinically-translatable redox imaging methods developed in the Chance laboratory have been used for imaging mitochondrial metabolic states in tissues. The fluorescence of reduced pyridine nucleotide (PN or NADH) and oxidized flavoproteins (Fp) in the respiratory chain is sensitive to intracellular redox states. The redox ratios, i.e., Fp/(Fp+NADH) and NADH/(Fp+NADH) provide important metabolic information in living tissues. Usually the higher the metabolic flux, the less NADH, the more oxidized Fp, and the higher Fp redox ratio. Snap-freezing tissue samples under the liquid nitrogen condition preserves the tissue metabolic state in vivo. Here we report our work on the calibration of a homebuilt Charged Coupled Device (CCD) cryogenic redox imager using a series of snap-frozen solution standards of NADH and Fp. The NADH concentration ranged from 0-1318 μM and Fp from 0-719 μM. The sensitivity ratio of NADH and Fp channels was determined from the slope ratio of the two calibration curves and was used to correct the redox ratio of a human melanoma mouse xenograft. The NADH and Fp reference standards were placed adjacent to the tissue samples and their emission intensities were used to quantitatively determine the concentrations of NADH and Fp in a mouse xenograft of a human breast cancer line. Our method of imaging tissue samples along with reference NADH and Fp standards should facilitate the comparison of redox images obtained at different times or with different instrument parameters.

  2. Regulation of brain mitochondrial H2O2 production by membrane potential and NAD(P)H redox state.

    PubMed

    Starkov, Anatoly A; Fiskum, Gary

    2003-09-01

    Mitochondrial production of reactive oxygen species (ROS) at Complex I of the electron transport chain is implicated in the etiology of neural cell death in acute and chronic neurodegenerative disorders. However, little is known regarding the regulation of mitochondrial ROS production by NADH-linked respiratory substrates under physiologically realistic conditions in the absence of respiratory chain inhibitors. This study used Amplex Red fluorescence measurements of H2O2 to test the hypothesis that ROS production by isolated brain mitochondria is regulated by membrane potential (DeltaPsi) and NAD(P)H redox state. DeltaPsi was monitored by following the medium concentration of the lipophilic cation tetraphenylphosphonium with a selective electrode. NAD(P)H autofluorescence was used to monitor NAD(P)H redox state. While the rate of H2O2 production was closely related to DeltaPsi and the level of NAD(P)H reduction at high values of DeltaPsi, 30% of the maximal rate of H2O2 formation was still observed in the presence of uncoupler (p-trifluoromethoxycarbonylcyanide phenylhydrazone) concentrations that provided for maximum depolarization of DeltaPsi and oxidation of NAD(P)H. Our findings indicate that ROS production by mitochondria oxidizing physiological NADH-dependent substrates is regulated by DeltaPsi and by the NAD(P)H redox state over ranges consistent with those that exist at different levels of cellular energy demand.

  3. Faradic redox active material of Cu7S4 nanowires with a high conductance for flexible solid state supercapacitors

    NASA Astrophysics Data System (ADS)

    Javed, Muhammad Sufyan; Dai, Shuge; Wang, Mingjun; Xi, Yi; Lang, Qiang; Guo, Donglin; Hu, Chenguo

    2015-08-01

    The exploration of high Faradic redox active materials with the advantages of low cost and low toxicity has been attracting great attention for producing high energy storage supercapacitors. Here, the high Faradic redox active material of Cu7S4-NWs coated on a carbon fiber fabric (CFF) is directly used as a binder-free electrode for a high performance flexible solid state supercapacitor. The Cu7S4-NW-CFF supercapacitor exhibits excellent electrochemical performance such as a high specific capacitance of 400 F g-1 at the scan rate of 10 mV s-1 and a high energy density of 35 Wh kg-1 at a power density of 200 W kg-1, with the advantages of a light weight, high flexibility and long term cycling stability by retaining 95% after 5000 charge-discharge cycles at a constant current of 10 mA. The high Faradic redox activity and high conductance behavior of the Cu7S4-NWs result in a high pseudocapacitive performance with a relatively high specific energy and specific power. Such a new type of pseudocapacitive material of Cu7S4-NWs with its low cost is very promising for actual application in supercapacitors.The exploration of high Faradic redox active materials with the advantages of low cost and low toxicity has been attracting great attention for producing high energy storage supercapacitors. Here, the high Faradic redox active material of Cu7S4-NWs coated on a carbon fiber fabric (CFF) is directly used as a binder-free electrode for a high performance flexible solid state supercapacitor. The Cu7S4-NW-CFF supercapacitor exhibits excellent electrochemical performance such as a high specific capacitance of 400 F g-1 at the scan rate of 10 mV s-1 and a high energy density of 35 Wh kg-1 at a power density of 200 W kg-1, with the advantages of a light weight, high flexibility and long term cycling stability by retaining 95% after 5000 charge-discharge cycles at a constant current of 10 mA. The high Faradic redox activity and high conductance behavior of the Cu7S4-NWs result in

  4. Assessing the effect of humic acid redox state on organic pollutant sorption by combined electrochemical reduction and sorption experiments.

    PubMed

    Aeschbacher, Michael; Brunner, Sibyl H; Schwarzenbach, René P; Sander, Michael

    2012-04-03

    Natural Organic Matter (NOM) is a major sorbent for organic pollutants in soils and sediments. While sorption under oxic conditions has been well investigated, possible changes in the sorption capacity of a given NOM induced by reduction have not yet been studied. Reduction of quinones to hydroquinones, the major redox active moieties in NOM, increases the number of H-donor moieties and thus may affect sorption. This work compares the sorption of four nonionic organic pollutants of different polarities (naphthalene, acetophenone, quinoline, and 2-naphthol), and of the organocation paraquat to unreduced and electrochemically reduced Leonardite Humic Acid (LHA). The redox states of reduced and unreduced LHA in all sorption experiments were stable, as demonstrated by a spectrophotometric 2,6-dichlorophenol indophenol reduction assay. The sorption isotherms of the nonionic pollutants were highly linear, while paraquat sorption was strongly concentration dependent. LHA reduction did not result in significant changes in the sorption of all tested compounds, not even of the cationic paraquat at pH 7, 9, and 11. This work provides the first evidence that changes in NOM redox state do not largely affect organic pollutant sorption, suggesting that current sorption models are applicable both to unreduced and to reduced soil and sediment NOM.

  5. Vitamin C in Health and Disease: Its Role in the Metabolism of Cells and Redox State in the Brain.

    PubMed

    Figueroa-Méndez, Rodrigo; Rivas-Arancibia, Selva

    2015-01-01

    Ever since Linus Pauling published his studies, the effects of vitamin C have been surrounded by contradictory results. This may be because its effects depend on a number of factors such as the redox state of the body, the dose used, and also on the tissue metabolism. This review deals with vitamin C pharmacokinetics and its participation in neurophysiological processes, as well as its role in the maintenance of redox balance. The distribution and the concentration of vitamin C in the organs depend on the ascorbate requirements of each and on the tissue distribution of sodium-dependent vitamin C transporter 1 and 2 (SVCT1 and SVCT2). This determines the specific distribution pattern of vitamin C in the body. Vitamin C is involved in the physiology of the nervous system, including the support and the structure of the neurons, the processes of differentiation, maturation, and neuronal survival; the synthesis of catecholamine, and the modulation of neurotransmission. This antioxidant interacts with self-recycling mechanisms, including its participation in the endogenous antioxidant system. We conclude that the pharmacokinetic properties of ascorbate are related to the redox state and its functions and effects in tissues.

  6. Vitamin C in Health and Disease: Its Role in the Metabolism of Cells and Redox State in the Brain

    PubMed Central

    Figueroa-Méndez, Rodrigo; Rivas-Arancibia, Selva

    2015-01-01

    Ever since Linus Pauling published his studies, the effects of vitamin C have been surrounded by contradictory results. This may be because its effects depend on a number of factors such as the redox state of the body, the dose used, and also on the tissue metabolism. This review deals with vitamin C pharmacokinetics and its participation in neurophysiological processes, as well as its role in the maintenance of redox balance. The distribution and the concentration of vitamin C in the organs depend on the ascorbate requirements of each and on the tissue distribution of sodium-dependent vitamin C transporter 1 and 2 (SVCT1 and SVCT2). This determines the specific distribution pattern of vitamin C in the body. Vitamin C is involved in the physiology of the nervous system, including the support and the structure of the neurons, the processes of differentiation, maturation, and neuronal survival; the synthesis of catecholamine, and the modulation of neurotransmission. This antioxidant interacts with self-recycling mechanisms, including its participation in the endogenous antioxidant system. We conclude that the pharmacokinetic properties of ascorbate are related to the redox state and its functions and effects in tissues. PMID:26779027

  7. Detecting changes in the thiol redox state of proteins following a decrease in oxygen concentration using a dual labeling technique.

    PubMed

    Lui, James K C; Lipscombe, Richard; Arthur, Peter G

    2010-01-01

    Cells are routinely exposed to hyperoxic conditions when cultured in the presence of 95% air and 5% carbon dioxide. Hyperoxic conditions can increase the generation of reactive oxygen species and cause oxidative stress. Oxidative stress has been proposed to cause cells in culture to behave differently from cells in vivo. One route by which oxidative stress could affect cellular function is through alterations in protein function caused by the oxidation of thiol groups (-SH) of redox-sensitive cysteine residues. To test whether changes in oxygen concentration were sufficient to cause changes in the thiol redox state of proteins, we developed a sensitive method involving the labeling of reduced and oxidized cysteine residues with fluorescent tags. Using this dual labeling method, we found 62 of 411 protein spots that were significantly more reduced following a 30 min decrease in oxygen concentration. We conclude that the elevated oxygen concentration characteristic of typical cell culture conditions has the potential to affect cellular behavior through changes in the thiol redox state of proteins.

  8. A new solid-state microelectrode for measuring intracellular chloride activities.

    PubMed

    Armstrong, W M; Wojtkowski, W; Bixenman, W R

    1977-02-14

    Solid-state microelectrodes from measuring intracellular Cl activity (alphaiCl) were made by sealing the tips of tapered glass capillaries (tip diameter 0.3 mum), coating them under vacuum with a 0.2-0.3 mum thick layer of spectrscopic grade silver, and sealing them (except for the terminal 2-5 mum of the tip) inside tapered glass shields. 106 microelectrodes had an average slope of 55.0+/- 0.6 m V (S,E,) per decade c hange in alphaCl. Tip resistance was (77.1+/- 3.1) x 10(9) omega(n=30). Electrode response was rapid (10-20 s), was unaffected by HCO3, H2PO4, HPO42 or protein, and remained essentially unchanged over a 24-h period. AlphaiCl in frog sartorius muscle fibers and epithelial cells of bullfrog small intestine was measured in vitro. In both tissues, alphaiCl significantly exceeded the value corresponding to equlibrium ditribution of Cl across the cell membrane.

  9. Proteomics links the redox state to calcium signaling during bleaching of the scleractinian coral Acropora microphthalma on exposure to high solar irradiance and thermal stress.

    PubMed

    Weston, Andrew J; Dunlap, Walter C; Beltran, Victor H; Starcevic, Antonio; Hranueli, Daslav; Ward, Malcolm; Long, Paul F

    2015-03-01

    Shipboard experiments were each performed over a 2 day period to examine the proteomic response of the symbiotic coral Acropora microphthalma exposed to acute conditions of high temperature/low light or high light/low temperature stress. During these treatments, corals had noticeably bleached. The photosynthetic performance of residual algal endosymbionts was severely impaired but showed signs of recovery in both treatments by the end of the second day. Changes in the coral proteome were determined daily and, using recently available annotated genome sequences, the individual contributions of the coral host and algal endosymbionts could be extracted from these data. Quantitative changes in proteins relevant to redox state and calcium metabolism are presented. Notably, expression of common antioxidant proteins was not detected from the coral host but present in the algal endosymbiont proteome. Possible roles for elevated carbonic anhydrase in the coral host are considered: to restore intracellular pH diminished by loss of photosynthetic activity, to indirectly limit intracellular calcium influx linked with enhanced calmodulin expression to impede late-stage symbiont exocytosis, or to enhance inorganic carbon transport to improve the photosynthetic performance of algal symbionts that remain in hospite. Protein effectors of calcium-dependent exocytosis were present in both symbiotic partners. No caspase-family proteins associated with host cell apoptosis, with exception of the autophagy chaperone HSP70, were detected, suggesting that algal loss and photosynthetic dysfunction under these experimental conditions were not due to host-mediated phytosymbiont destruction. Instead, bleaching occurred by symbiont exocytosis and loss of light-harvesting pigments of algae that remain in hospite. These proteomic data are, therefore, consistent with our premise that coral endosymbionts can mediate their own retention or departure from the coral host, which may manifest as

  10. Control of glucokinase translocation in rat hepatocytes by sorbitol and the cytosolic redox state.

    PubMed Central

    Agius, L

    1994-01-01

    In rat hepatocytes cultured in 5 mM glucose, glucokinase activity is present predominantly in a bound state, and during permeabilization of the cells with digitonin in the presence of Mg2+ less than 20% of glucokinase activity is released. However, incubation of hepatocytes with a higher [glucose] [concn. giving half-maximal activation (A50) 15 mM] or with fructose (A50 50 microM) causes translocation of glucokinase from its Mg(2+)-dependent binding site to an alternative site [Agius and Peak (1993) Biochem. J. 296, 785-796]. A comparison of various substrates showed that sorbitol (A50 8 microM) was 6-fold more potent than fructose at causing glucokinase translocation, whereas tagatose was as potent and mannitol was > 10-fold less potent (A50 550 microM). These substrates also stimulate glucose conversion into glycogen with a similar relative potency, suggesting that conversion of glucose into glycogen is dependent on the binding and/or location of glucokinase within the hepatocyte. Ethanol and glycerol inhibited the effects of fructose, sorbitol and glucose on glucokinase translocation, whereas dihydroxy-acetone had a small additive effect at sub-maximal substrate stimulation. The converse effects of glycerol and dihydroxy-acetone suggest a role for the cytosolic NADH/NAD+ redox state in controlling glucokinase translocation. Titrations with three competitive inhibitors of glucokinase did not provide evidence for involvement of glucokinase flux in glucose-induced glucokinase translocation: N-acetylglucosamine inhibited glucose conversion into glycogen, but not glucose-induced glucokinase translocation; glucosamine partially suppressed glucose-induced and fructose-induced glucokinase translocation, at concentrations that caused total inhibition of glucose conversion into glycogen; D-mannoheptulose increased glucokinase release and had an additive effect with glucose. 3,3'-Tetramethylene-glutaric acid (5 mM), an inhibitor of aldose reductase, inhibited glucokinase

  11. Electrochemical Detection of Circadian Redox Rhythm in Cyanobacterial Cells via Extracellular Electron Transfer.

    PubMed

    Nishio, Koichi; Pornpitra, Tunanunkul; Izawa, Seiichiro; Nishiwaki-Ohkawa, Taeko; Kato, Souichiro; Hashimoto, Kazuhito; Nakanishi, Shuji

    2015-06-01

    Recent research on cellular circadian rhythms suggests that the coupling of transcription-translation feedback loops and intracellular redox oscillations is essential for robust circadian timekeeping. For clarification of the molecular mechanism underlying the circadian rhythm, methods that allow for the dynamic and simultaneous detection of transcription/translation and redox oscillations in living cells are needed. Herein, we report that the cyanobacterial circadian redox rhythm can be electrochemically detected based on extracellular electron transfer (EET), a process in which intracellular electrons are exchanged with an extracellular electrode. As the EET-based method is non-destructive, concurrent detection with transcription/translation rhythm using bioluminescent reporter strains becomes possible. An EET pathway that electrochemically connected the intracellular region of cyanobacterial cells with an extracellular electrode was constructed via a newly synthesized electron mediator with cell membrane permeability. In the presence of the mediator, the open circuit potential of the culture medium exhibited temperature-compensated rhythm with approximately 24 h periodicity. Importantly, such circadian rhythm of the open circuit potential was not observed in the absence of the electron mediator, indicating that the EET process conveys the dynamic information regarding the intracellular redox state to the extracellular electrode. These findings represent the first direct demonstration of the intracellular circadian redox rhythm of cyanobacterial cells.

  12. TmpL, a Transmembrane Protein Required for Intracellular Redox Homeostasis and Virulence in a Plant and an Animal Fungal Pathogen

    PubMed Central

    Kim, Kwang-Hyung; Willger, Sven D.; Park, Sang-Wook; Puttikamonkul, Srisombat; Grahl, Nora; Cho, Yangrae; Mukhopadhyay, Biswarup; Cramer, Robert A.; Lawrence, Christopher B.

    2009-01-01

    The regulation of intracellular levels of reactive oxygen species (ROS) is critical for developmental differentiation and virulence of many pathogenic fungi. In this report we demonstrate that a novel transmembrane protein, TmpL, is necessary for regulation of intracellular ROS levels and tolerance to external ROS, and is required for infection of plants by the necrotroph Alternaria brassicicola and for infection of mammals by the human pathogen Aspergillus fumigatus. In both fungi, tmpL encodes a predicted hybrid membrane protein containing an AMP-binding domain, six putative transmembrane domains, and an experimentally-validated FAD/NAD(P)-binding domain. Localization and gene expression analyses in A. brassicicola indicated that TmpL is associated with the Woronin body, a specialized peroxisome, and strongly expressed during conidiation and initial invasive growth in planta. A. brassicicola and A. fumigatus ΔtmpL strains exhibited abnormal conidiogenesis, accelerated aging, enhanced oxidative burst during conidiation, and hypersensitivity to oxidative stress when compared to wild-type or reconstituted strains. Moreover, A. brassicicola ΔtmpL strains, although capable of initial penetration, exhibited dramatically reduced invasive growth on Brassicas and Arabidopsis. Similarly, an A. fumigatus ΔtmpL mutant was dramatically less virulent than the wild-type and reconstituted strains in a murine model of invasive aspergillosis. Constitutive expression of the A. brassicicola yap1 ortholog in an A. brassicicola ΔtmpL strain resulted in high expression levels of genes associated with oxidative stress tolerance. Overexpression of yap1 in the ΔtmpL background complemented the majority of observed developmental phenotypic changes and partially restored virulence on plants. Yap1-GFP fusion strains utilizing the native yap1 promoter exhibited constitutive nuclear localization in the A. brassicicola ΔtmpL background. Collectively, we have discovered a novel protein

  13. Cancer chemoprevention and mitochondria: targeting apoptosis in transformed cells via the disruption of mitochondrial bioenergetics/redox state.

    PubMed

    Hail, Numsen; Lotan, Reuben

    2009-01-01

    Cancer chemoprevention employs agents that block, hinder, or reverse tumorigenesis to prevent malignancy. Several putative cancer chemopreventive agents promote apoptosis in transformed cells initiated in animal carcinogenesis models or identified in human subjects, and/or in tumor cells cultured in vitro. Consequently, apoptosis induction is increasingly valued as a biologically significant anticancer mechanism in the arena of chemoprevention. In vitro studies suggest that the permeabilization of mitochondrial membranes is an important mechanistic determinant associated with the apoptosis induced by these agents. Mitochondrial membrane permeabilization (MMP) may occur via the control of proapoptotic Bcl-2 family members, and/or by the induction of the mitochondrial permeability transition. Both of these cell death-inducing regulatory mechanisms are ultimately responsive to the bioenergetic status/redox state of mitochondria. Interestingly, in addition to inducing MMP, various chemopreventive agents can directly modulate mitochondrial bioenergetics and/or redox tone in transformed cells. This review will examine prospective mechanisms associated with the disruption of mitochondrial function by chemopreventive agents that affect MMP and apoptosis. In doing so, we will construct a paradigm supporting the notion that the bioenergetic and/or redox characteristics of the mitochondria in transformed cells are important targets in the chemoprevention of cancer.

  14. Cooling History and Redox State of NWA 8694 Chassignite: Comparison with Chassigny and NWA 2737

    NASA Technical Reports Server (NTRS)

    Mikouchi, T.; Takenouchi, A.; Zolensky, M. E.

    2016-01-01

    NWA 8694 is a new chassignite whose constituent minerals are more Fe-rich than those in the other known chassignites (Chassigny and NWA 2737), and may suggest a petrogenetic relationship to nakhlites. In this abstract we report mineralogy of NWA 8694 to infer its cooling rate and redox state, and discuss its thermal and shock history in comparison with other chassignites. NWA 8694 is a cumulate dunite of approximately 2 mm olivine with interstitial pyroxene and feldspar. Olivine is homogeneous (Fo(sub 55-56)), but Ca decreases at the approximately 50-100 micrometer rim (0.25-0.1 wt% CaO). Because the Ca-depleted rim is narrower than those in other chassignites (approximately 50 ?micrometer), NWA 8694 may have cooled slightly faster than the others (approximately 30 C/yr), but would be in the same order. Pyroxenes are low- and high-Ca pyroxenes, both exhibiting sub-micron exsolution textures (0.2-0.3 micrometer wide lamellae with the spacing of 0.8-1.8 micrometers). Although the low-Ca pyroxene host has an orthopyroxene composition (Wo approximately 2), the EBSD analysis suggests a pigeonite structure (P2(sub 1)/c), which is also reported from the Chassigny pyroxene. The size of exsolution texture is a bit smaller, but broadly similar to those in other chassignites, implying a similar fast cooling rate (35-43 C/yr). Feldspars are isotropic (plagioclase: clustered around An25Or10, K-feldspar: approximately An19Or78), suggestive of extensive shock metamorphism, consistent with undulatory extinction of olivine. Feldspar compositions are around the equilibrium isotherm of approximately 800 C. The olivine and chromite compositions give an equilibration temperature of 760-810 C and logfO2 of QFM+/-0.3. The inferred fast cooling rate and high fO2 of NWA 8694 are both similar to those of Chassigny and NWA 2737, and suggest a common formation condition (e.g., thick lava flow or shallow intrusion) under oxidizing condition. The Fe-rich mineral compositions of NWA 8694 may be

  15. The Valence State of Silicon and Redox Dynamics in Aluminosilicate Melts

    NASA Astrophysics Data System (ADS)

    Cooper, R. F.; Pettersen, C.; Everman, R. L.

    2005-12-01

    Physicists have long been aware of the many valence states of Si and the roles these play in the kinetics of thermal oxidation of Si single crystals and the molecular structure of the amorphous oxide film (e.g., Borman et al., 1991). Similarly, the dynamics of oxidation and of vaporization of SiC are also affected by the presence of Si2+ in the amorphous silica surface film (e.g., Dunham et al., 1998; Mendybaev et al., 2002). Nevertheless, Si2+,4+ heterovalency is little considered in redox studies of silicate melts as reported in the petrology literature. We have performed experiments in which a liquid bronze (Cu,Sn) alloy was reacted with (1) a magnesium aluminosilicate melt and (2) a Zn2+-doped magnesium aluminosilicate melt, all done at a low oxygen fugacity (sufficient to keep the metal alloy from oxidizing in reaction with the gas environment). The driving potential for metal melt-silicate melt reaction has two components: (a) reduction of the silicate melt and oxidation of the metal alloy; (b) formation of a homogeneous silicate solution that incorporates ionic Cu and Sn. The reaction morphologies present compelling evidence that Si4+ in the silicate melt is reduced in part to Si2+, initially so as to incorporate Cu+,2+ into the melt; as the reaction proceeds, however, the Si2+ mobility becomes important in charge-compensation of the "inward" flux of Sn2+. Addition of Zn2+ to the starting silicate melt forces a spatially periodic variation in the silicate melt structure (as suggested by the chemistry) as the reaction proceeds. In separate experiments, reduction of an FeO-bearing calcium-magnesium aluminosilicate melt in a CO-rich environment creates a reaction morphology suggestive of reduction of Si4+ to facilitate the incorporation of carbonate ions into the melt. These experiments are perhaps exotic; nevertheless, they provoke the consideration of the potential role(s) played by silicon valence in any "self-buffering" process associated with the evolution

  16. A State-of-the-Science Hg Redox Mechanism for Atmospheric Models: Constraints from Observations and Global Implications

    NASA Astrophysics Data System (ADS)

    Horowitz, H.; Jacob, D. J.; Amos, H. M.; Streets, D. G.; Zhang, Y.; Dibble, T. S.; Slemr, F.; Sunderland, E. M.

    2015-12-01

    Mercury (Hg) in the atmosphere cycles between two redox forms, Hg0 and HgII. Hg0 has a lifetime of ~1 year allowing near-global transport, while HgII is efficiently removed by deposition within weeks. Understanding atmospheric Hg redox chemistry is critical to determining the patterns of deposition to the surface, where Hg can be transformed to the bioaccumulative neurotoxin, methylmercury. We present a state-of-the-science redox mechanism for use in atmospheric models, with new theoretical data, which we implement in a global 3-D chemical transport model (GEOS-Chem). We evaluate our simulation against atmospheric observations and examine implications for Hg deposition. Modeled HgII wet deposition depends on the oxidation of anthropogenic, ocean, and soil Hg0 emissions and the reduction of emitted anthropogenic HgII. We present a new global anthropogenic atmospheric Hg emissions inventory for 1990 - 2010 with improved speciation of power plant emissions and regional commercial Hg emissions. The seasonal cycle of ocean evasion is also critical to atmospheric Hg variability. We present an advance in our ability to model atmosphere-ocean exchange of Hg, through more realistic ocean circulation from the 3-D MITgcm. Our results suggest Br is the dominant oxidant in the stratosphere, consistent with constraints from aircraft observations of the Hg gradient with depth into the stratosphere. The proposed redox mechanism leads to increased HgII deposition to the Tropics, with implications for tropical surface ocean enrichment, and decreased deposition to the Southern Ocean. Within the uncertainty of Hg0 oxidation rates, we find atmospheric HgII reduction is still needed. We find changes in speciated Hg emissions due to emissions controls can explain recent observed regional trends in atmospheric Hg. These have shifted power plant impacts to relatively more global than local Hg deposition. Coupling to the more realistic 3-D ocean model improves simulated atmospheric Hg

  17. Predicting the redox state and secondary structure of cysteine residues using multi-dimensional classification analysis of NMR chemical shifts.

    PubMed

    Wang, Ching-Cheng; Lai, Wen-Chung; Chuang, Woei-Jer

    2016-09-01

    A tool for predicting the redox state and secondary structure of cysteine residues using multi-dimensional analyses of different combinations of nuclear magnetic resonance (NMR) chemical shifts has been developed. A data set of cysteine [Formula: see text], (13)C(α), (13)C(β), (1)H(α), (1)H(N), and (15)N(H) chemical shifts was created, classified according to redox state and secondary structure, using a library of 540 re-referenced BioMagResBank (BMRB) entries. Multi-dimensional analyses of three, four, five, and six chemical shifts were used to derive rules for predicting the structural states of cysteine residues. The results from 60 BMRB entries containing 122 cysteines showed that four-dimensional analysis of the C(α), C(β), H(α), and N(H) chemical shifts had the highest prediction accuracy of 100 and 95.9 % for the redox state and secondary structure, respectively. The prediction of secondary structure using 3D, 5D, and 6D analyses had the accuracy of ~90 %, suggesting that H(N) and [Formula: see text] chemical shifts may be noisy and made the discrimination worse. A web server (6DCSi) was established to enable users to submit NMR chemical shifts, either in BMRB or key-in formats, for prediction. 6DCSi displays predictions using sets of 3, 4, 5, and 6 chemical shifts, which shows their consistency and allows users to draw their own conclusions. This web-based tool can be used to rapidly obtain structural information regarding cysteine residues directly from experimental NMR data.

  18. Novel double-decker phthalocyaninato terbium(III) single molecule magnets with stabilised redox states.

    PubMed

    Gonidec, Mathieu; Amabilino, David B; Veciana, Jaume

    2012-11-28

    Double-decker phthalocyanine lanthanide complexes are single molecule magnets (SMMs) presenting a thermally activated magnetic relaxation with relatively high effective barriers. For this reason they are potential candidates as components for data storage and spintronic devices. One of the disadvantages of these compounds is their redox instability: they are oxidized or reduced in the presence of mild oxidizing and reducing agents. To solve this issue, we designed, prepared and characterized new double-decker phthalocyanine based SMMs bearing electron withdrawing groups and therefore presenting an increased redox stability. In the present article, the synthesis and characterization of these novel compounds is presented and we demonstrate how the magnetic behavior of the complexes is virtually identical to that of the parent unsubstituted compounds.

  19. Impact-related thermal effects on the redox state of Ca-pyroxene

    NASA Astrophysics Data System (ADS)

    McCanta, M. C.; Dyar, M. D.

    2017-02-01

    Oxidation is observed in Ca-pyroxene subjected to a range of shock pressures (21-59 GPa). Changes in the pyroxene redox ratio as measured by the changes in %Fe3+ ranged from 2-6 times the starting composition. Mössbauer and reflectance spectroscopy record the changing Fe3+ concentration as a preferential oxidation of Fe2+ in the M2 crystallographic site. The oxidation is also accompanied by mechanical changes in the pyroxene crystals including fracturing, linear defects, and twinning. As oxygen fugacity is often calculated using mineral redox ratios and thought to represent the prevailing fO2 during crystallization, it is imperative to recognize that the fO2 values measured in impact-derived materials may represent that of the impact and not the magma source region.

  20. Contribution of Fdh3 and Glr1 to Glutathione Redox State, Stress Adaptation and Virulence in Candida albicans

    PubMed Central

    Tillmann, Anna T.; Strijbis, Karin; Cameron, Gary; Radmaneshfar, Elahe; Thiel, Marco; Munro, Carol A.; MacCallum, Donna M.; Distel, Ben; Gow, Neil A. R.; Brown, Alistair J. P.

    2015-01-01

    The major fungal pathogen of humans, Candida albicans, is exposed to reactive nitrogen and oxygen species following phagocytosis by host immune cells. In response to these toxins, this fungus activates potent anti-stress responses that include scavenging of reactive nitrosative and oxidative species via the glutathione system. Here we examine the differential roles of two glutathione recycling enzymes in redox homeostasis, stress adaptation and virulence in C. albicans: glutathione reductase (Glr1) and the S-nitrosoglutathione reductase (GSNOR), Fdh3. We show that the NADPH-dependent Glr1 recycles GSSG to GSH, is induced in response to oxidative stress and is required for resistance to macrophage killing. GLR1 deletion increases the sensitivity of C. albicans cells to H2O2, but not to formaldehyde or NO. In contrast, Fdh3 detoxifies GSNO to GSSG and NH3, and FDH3 inactivation delays NO adaptation and increases NO sensitivity. C. albicans fdh3⎔ cells are also sensitive to formaldehyde, suggesting that Fdh3 also contributes to formaldehyde detoxification. FDH3 is induced in response to nitrosative, oxidative and formaldehyde stress, and fdh3Δ cells are more sensitive to killing by macrophages. Both Glr1 and Fdh3 contribute to virulence in the Galleria mellonella and mouse models of systemic infection. We conclude that Glr1 and Fdh3 play differential roles during the adaptation of C. albicans cells to oxidative, nitrosative and formaldehyde stress, and hence during the colonisation of the host. Our findings emphasise the importance of the glutathione system and the maintenance of intracellular redox homeostasis in this major pathogen. PMID:26039593

  1. Content of redox-active compounds (ie, antioxidants) in foods consumed in the United States.

    PubMed

    Halvorsen, Bente L; Carlsen, Monica H; Phillips, Katherine M; Bøhn, Siv K; Holte, Kari; Jacobs, David R; Blomhoff, Rune

    2006-07-01

    Supplements containing ascorbic acid, alpha-tocopherol, or beta-carotene do not protect against oxidative stress-related diseases in most randomized intervention trials. We suggest that other redox-active phytochemicals may be more effective and that a combination of different redox-active compounds (ie, antioxidants or reductants) may be needed for proper protection against oxidative damage. We aimed to generate a ranked food table with values for total content of redox-active compounds to test this alternative antioxidant hypothesis. An assay that measures the total concentration of redox-active compounds above a certain cutoff reduction potential was used to analyze 1113 food samples obtained from the US Department of Agriculture National Food and Nutrient Analysis Program. Large variations in the content of antioxidants were observed in different foods and food categories. The food groups spices and herbs, nuts and seeds, berries, and fruit and vegetables all contained foods with very high antioxidant contents. Most food categories also contained products almost devoid of antioxidants. Of the 50 food products highest in antioxidant concentrations, 13 were spices, 8 were in the fruit and vegetables category, 5 were berries, 5 were chocolate-based, 5 were breakfast cereals, and 4 were nuts or seeds. On the basis of typical serving sizes, blackberries, walnuts, strawberries, artichokes, cranberries, brewed coffee, raspberries, pecans, blueberries, ground cloves, grape juice, and unsweetened baking chocolate were at the top of the ranked list. This ranked antioxidant food table provides a useful tool for investigations into the possible health benefit of dietary antioxidants.

  2. West Valley glass product qualification durability studies, FY 1987--1988: Effects of composition, redox state, thermal history, and groundwater

    SciTech Connect

    Reimus, M.A.H.; Piepel, G.F.; Mellinger, G.B.; Bunnell, L.R.

    1988-11-01

    The product qualification subtask of the West Valley Support Task (WVST) at Pacific Northwest Laboratory (PNL) provides support for the waste form qualification efforts at West Valley Nuclear Services Co. Testing is being conducted to determine waste form chemical durability in support of these efforts. The effects of composition, ferrous/ferric ratio (redox state), thermal history, and groundwater are being investigated. Glasses were tested using modified Materials Characterization Center (MCC) -3 and MCC-1 test methods. Results obtained in fiscal years (FY) 1987 and 1988 are presented here. 13 refs., 27 figs., 36 tabs.

  3. Quantitative analysis of the redox states of cytochromes in a living L929 (NCTC) cell by resonance Raman microspectroscopy.

    PubMed

    Kakita, Minoru; Okuno, Masanari; Hamaguchi, Hiro-o

    2013-03-01

    Raman spectra and images of a living L929 (NCTC) cell have been measured with 532 nm excitation. Both reduced and oxidized forms of cytochromes b and c (cyt b and cyt c) have been observed in situ without any pretreatment. The redox states of cyts b and c have been assessed quantitatively with a spectral analysis. It has been found that reduced cyt c is more abundant than oxidized cyt c, while oxidized cyt b is slightly more abundant than reduced cyt b in a living cell. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Nanosecond ratio imaging of redox states in tumor cell spheroids using light sheet-based fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Schickinger, Sarah; Bruns, Thomas; Wittig, Rainer; Weber, Petra; Wagner, Michael; Schneckenburger, Herbert

    2013-12-01

    A new concept of three-dimensional imaging of tumor cell spheroids by light sheet-based fluorescence microscopy and nanosecond ratio imaging is described. Due to its low light dose and alternative excitation by two laser wavelengths (391 and 470 nm), this method maintains cell viability and permits recording of real-time kinetics. A genetically encoded sensor permits measurement of the redox state of glutathione and visualization of the impact of oxygen radicals. The pharmaceutically relevant system is tested upon addition of an oxidizing agent (H2O2), as well as upon addition of the apoptosis-inducing agent staurosporine.

  5. Turnover control of photosystem II: Use of redox-active herbicides to form the S[sub 3] state

    SciTech Connect

    Bocarsly, J.R.; Brudvig, G.W. )

    1992-12-02

    The O[sub 2]-evolving center of photosystem II, which contains an active-site tetramanganese-oxo cluster, catalyzes the four-electron oxidation of two water molecules to dioxygen, with the concomitant production of four H[sup +] and four electrons. During catalytic turnover, the manganese-oxo cluster steps through five intermediate oxidation states, which are known as the S[sub i] states (i = 0-4). While methods have been found to manipulate the system into S[sub 1] and S[sub 2] in high yields, efficient production of the S[sub 3] state in good yield at high concentration has not yet been achieved. Previous methods have suffered from the requirement of low protein concentration so that actinic flashes are saturating; the use of temperature to control S-state advancement under continuous illumination, which can lead to S-state scrambling; or the use of herbicides that bind to the Q[sub B] site and restrict the system to one turnover. The authors describe here a method for the high-yield production of the S[sub 3] state in highly-concentrated samples of photosystem II, through the use of electron-accepting herbicides which bind to the Q[sub B] site. Redox-active herbicides can be used, in principle, to limit S-state cycling to any desired number of turnovers, given the appropriate herbicide. This work has fundamental methodological implications not only for the study of photosystem II but also for other multistate redox protein systems.

  6. The Intra- or Extracellular Redox State Was Not Affected by a High vs. Low Glycemic Response Diet in Mice.

    PubMed

    Kleckner, Amber S; Wong, Siu; Corkey, Barbara E

    2015-01-01

    A low glycemic response (LGR) vs. high glycemic response (HGR) diet helps curtail the development of obesity and diabetes, though the mechanisms are unknown. We hypothesized that consumption of a HGR vs. a LGR diet would lead to a more oxidized circulating redox state and predicted that a HGR diet would increase fat accumulation, reduce insulin sensitivity, and impair metabolic acclimation to a high fat diet in a mouse model. Hence, male C57BL/6 mice consumed a HGR or LGR diet for 16 weeks and a subset of the mice subsequently consumed a high fat diet for 4 weeks. We found that body mass increased at a faster rate for those consuming the HGR diet. Percent body fat was greater and percent lean mass was lesser in the HGR group starting at 12 weeks. However, the groups did not differ in terms of glucose tolerance at week 14 and metabolic parameters (respiratory exchange ratio, heat production, activity) at weeks 4 or 15. Moreover, mice on either diet did not show differences in metabolic acclimation to the high fat leg of the study. At the termination of the study, the groups did not differ in terms of redox pairs (lactate/pyruvate and β-hydroxybutyrate/acetoacetate) or thioredoxin reductase activity in blood. Also, total and oxidized glutathione levels and lipid peroxidation were similar in blood and liver. Correlations between baseline measures, longitudinal parameters, environmental conditions, and terminal metrics revealed that individual mice have innate propensities to metabolic regulation that may be difficult to perturb with diet alone; for example, starting mass correlated negatively with energy expenditure 4 weeks into the study and total hepatic glutathione at the end of the study. In conclusion, these data suggest that the mechanism by which HGR carbohydrates contributes to obesity is not via prolonged oxidation of the circulating redox state.

  7. The Intra- or Extracellular Redox State Was Not Affected by a High vs. Low Glycemic Response Diet in Mice

    PubMed Central

    Kleckner, Amber S.; Wong, Siu; Corkey, Barbara E.

    2015-01-01

    A low glycemic response (LGR) vs. high glycemic response (HGR) diet helps curtail the development of obesity and diabetes, though the mechanisms are unknown. We hypothesized that consumption of a HGR vs. a LGR diet would lead to a more oxidized circulating redox state and predicted that a HGR diet would increase fat accumulation, reduce insulin sensitivity, and impair metabolic acclimation to a high fat diet in a mouse model. Hence, male C57BL/6 mice consumed a HGR or LGR diet for 16 weeks and a subset of the mice subsequently consumed a high fat diet for 4 weeks. We found that body mass increased at a faster rate for those consuming the HGR diet. Percent body fat was greater and percent lean mass was lesser in the HGR group starting at 12 weeks. However, the groups did not differ in terms of glucose tolerance at week 14 and metabolic parameters (respiratory exchange ratio, heat production, activity) at weeks 4 or 15. Moreover, mice on either diet did not show differences in metabolic acclimation to the high fat leg of the study. At the termination of the study, the groups did not differ in terms of redox pairs (lactate/pyruvate and β-hydroxybutyrate/acetoacetate) or thioredoxin reductase activity in blood. Also, total and oxidized glutathione levels and lipid peroxidation were similar in blood and liver. Correlations between baseline measures, longitudinal parameters, environmental conditions, and terminal metrics revealed that individual mice have innate propensities to metabolic regulation that may be difficult to perturb with diet alone; for example, starting mass correlated negatively with energy expenditure 4 weeks into the study and total hepatic glutathione at the end of the study. In conclusion, these data suggest that the mechanism by which HGR carbohydrates contributes to obesity is not via prolonged oxidation of the circulating redox state. PMID:26030878

  8. Trace Element Pattern of Authigenic Pyrite: A Promising Proxy for the Redox State of Depositional Environment

    NASA Astrophysics Data System (ADS)

    Stueben, D.; Berner, Z. A.; Puchelt, H.; Noeltner, T.

    2002-12-01

    Authigenic pyrite is formed in a wide range of depositional conditions, including not only typically euxinic conditions (when it can precipitate as syngenetic pyrite already in the water column), but also the anoxic part of normal marine sediments, below the water/sediment interface. We investigated the response in trace element composition of pyrite to such environmental differences in 49 pyrite separates prepared from the cores recovered by a 15.2 m deep drilling executed at Weilstetten, in SW of Germany. The drilling crossed a sedimentary sequence, encompassing the transition from normal marine sediments of the Lias Epsilon-I to the black shales of the Posidonienschiefer (Lower Toarcian, Lias Epsilon-II, and -III). The trace element composition of pyrite was analyzed by means of ICP-MS and the results were evaluated in a broader geochemical context, including the isotopic composition of S in Pyrite, the S-, Ccarbonate-, and Corganic- content of the host rocks, as well as their isotopic composition (C and O). Results document a sudden change in trace element pattern of the pyrites, simultaneously with changes in other geochemical parameters and proxies at the transition mentioned above. The evaluation of the data by means of factor analysis shows that high contents of Co, Ni and Cu coupled with very low δ34S values are indicative for early diagenetic pyrites formed in the low-redox environment of the sediment, which, however, was still open for sulfate supply, but in the same time also permitted a backwards diffusion and reoxidation of the not reacted H2S. The open system conditions coupled with the disproportionation of sulfur species with intermediate oxidation states led to a strong fractionation of the S isotopes. In contrast, pyrites from black shales are characterized by relatively high concentrations of As, Mo and Sb and high δ34S values. Together with other parameters (S/Corg ratios, δ13Corg values) the data suggest that such pyrites were formed under

  9. Mitochondrial and cytosolic thiol redox state are not detectably altered in isolated human NADH:ubiquinone oxidoreductase deficiency.

    PubMed

    Verkaart, Sjoerd; Koopman, Werner J H; Cheek, Julia; van Emst-de Vries, Sjenet E; van den Heuvel, Lambertus W P J; Smeitink, Jan A M; Willems, Peter H G M

    2007-09-01

    Isolated complex I deficiency is the most common enzymatic defect of the oxidative phosphorylation (OXPHOS) system, causing a wide range of clinical phenotypes. We reported before that the rates at which reactive oxygen species (ROS)-sensitive dyes are converted into their fluorescent oxidation products are markedly increased in cultured skin fibroblasts of patients with nuclear-inherited isolated complex I deficiency. Using video-imaging microscopy we show here that these cells also display a marked increase in NAD(P)H autofluorescence. Linear regression analysis revealed a negative correlation with the residual complex I activity and a positive correlation with the oxidation rates of the ROS-sensitive dyes 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein and hydroethidine for a cohort of 10 patient cell lines. On the other hand, video-imaging microscopy of cells expressing reduction-oxidation sensitive GFP1 in either the mitochondrial matrix or cytosol showed the absence of any detectable change in thiol redox state. In agreement with this result, neither the glutathione nor the glutathione disulfide content differed significantly between patient and healthy fibroblasts. Finally, video-rate confocal microscopy of cells loaded with C11-BODIPY(581/591) demonstrated that the extent of lipid peroxidation, which is regarded as a measure of oxidative damage, was not altered in patient fibroblasts. Our results indicate that fibroblasts of patients with isolated complex I deficiency maintain their thiol redox state despite marked increases in ROS production.

  10. Association between life-span extension by caloric restriction and thiol redox state in two different strains of mice.

    PubMed

    Rebrin, Igor; Forster, Michael J; Sohal, Rajindar S

    2011-07-01

    The hypothesis that the life-extending effect of caloric restriction (CR) is associated with an attenuation of the age-related pro-oxidant shift in the thiol redox state was tested employing a novel experimental design. Amounts of GSH, GSSG, and protein mixed disulfides (Pr-SSG) in the skeletal muscle and liver were compared between two strains of mice that have similar life spans when fed ad libitum (AL), but different life spans under the standard CR regimen. The life span of one strain, C57BL/6, is extended under CR, whereas it remains unaffected in the other strain, DBA/2. Mice were fed AL or 40% less food starting at 4 months and compared at 6 and 24 months of age. The amounts of GSSG and Pr-SSG increased and the GSH:GSSG ratios decreased with age in both strains of AL-fed mice. CR prevented these age-related changes in the C57BL/6, whose life span is extended by CR, but not in the DBA/2 mice, in which it remains unaffected. CR enhanced the activity of glutamate-cysteine ligase in the C57BL/6, but not in the DBA/2 mice. The results suggest that longevity extension by CR may be associated with the attenuation of age-related pro-oxidizing shifts in the thiol redox state. Copyright © 2011 Elsevier Inc. All rights reserved.

  11. Omental adipocyte hypertrophy relates to coenzyme Q10 redox state and lipid peroxidation in obese women[S

    PubMed Central

    Grenier-Larouche, Thomas; Galinier, Anne; Casteilla, Louis; Carpentier, André C.; Tchernof, André

    2015-01-01

    Occurrence of oxidative stress in white adipose tissues contributes to its dysfunction and the development of obesity-related metabolic complications. Coenzyme Q10 (CoQ10) is the single lipophilic antioxidant synthesized in humans and is essential for electron transport during mitochondrial respiration. To understand the role of CoQ10 in adipose tissue physiology and dysfunction, the abundance of the oxidized and reduced (CoQ10red) isoforms of the CoQ10 were quantified in subcutaneous and omental adipose tissues of women covering the full range of BMI (from 21.5 to 53.2 kg/m2). Lean women displayed regional variations of CoQ10 redox state between the omental and subcutaneous depot, despite similar total content. Obese women had reduced CoQ10red concentrations in the omental depot, leading to increased CoQ10 redox state and higher levels of lipid hydroperoxide. Women with low omental CoQ10 content had greater visceral and subcutaneous adiposity, increased omental adipocyte diameter, and higher circulating interleukin-6 and C-reactive protein levels and were more insulin resistant. The associations between abdominal obesity-related cardiometabolic risk factors and CoQ10 content in the omental depot were abolished after adjustment for omental adipocyte diameter. This study shows that hypertrophic remodeling of visceral fat closely relates to depletion of CoQ10, lipid peroxidation, and inflammation. PMID:26239051

  12. REDOX state analysis of platinoid elements in simulated high-level radioactive waste glass by synchrotron radiation based EXAFS

    NASA Astrophysics Data System (ADS)

    Okamoto, Yoshihiro; Shiwaku, Hideaki; Nakada, Masami; Komamine, Satoshi; Ochi, Eiji; Akabori, Mitsuo

    2016-04-01

    Extended X-ray Absorption Fine Structure (EXAFS) analyses were performed to evaluate REDOX (REDuction and OXidation) state of platinoid elements in simulated high-level nuclear waste glass samples prepared under different conditions of temperature and atmosphere. At first, EXAFS functions were compared with those of standard materials such as RuO2. Then structural parameters were obtained from a curve fitting analysis. In addition, a fitting analysis used a linear combination of the two standard EXAFS functions of a given elements metal and oxide was applied to determine ratio of metal/oxide in the simulated glass. The redox state of Ru was successfully evaluated from the linear combination fitting results of EXAFS functions. The ratio of metal increased at more reducing atmosphere and at higher temperatures. Chemical form of rhodium oxide in the simulated glass samples was RhO2 unlike expected Rh2O3. It can be estimated rhodium behaves according with ruthenium when the chemical form is oxide.

  13. Comparison of thiol redox state of mitochondria and homogenates of various tissues between two strains of mice with different longevities

    PubMed Central

    Rebrin, Igor; Sohal, Rajindar S.

    2010-01-01

    The main purpose of this study was to determine if differences in life spans of two different strains of mice are associated with the thiol redox state of their tissues and mitochondria. A comparison, based on amounts of reduced and oxidized glutathione (GSH, GSSG) and reactive protein thiols, was made between short-lived SAM (P8) mice and the longer-lived C57BL/6 mice at 13 months of age. The average life span of the latter mouse strain is approximately 48% longer than the former strain. Analyses of plasma, tissue homogenates and mitochondria of liver, kidney, heart, brain and skeletal muscle indicated that, in general, amounts of GSH and reactive protein sulfhydryls and GSH:GSSG ratios were lower and concentrations of GSSG were higher in the SAM than the C57BL/6 mice. Differences in the redox state between the two strains were more consistent and pronounced in skeletal muscle than in other tissues, and in mitochondria than in their respective tissue homogenates. Overall, the results support the view that the shorter-lived SAM mice exhibit a relatively higher level of oxidative stress than the longer-lived C57BL/6 mice, which is consistent with the predictions of the oxidative stress hypothesis of aging. Intra-species comparisons may be useful for the identification of biochemical characteristics associated with the variations in life spans. PMID:15501021

  14. Fe-based redox state of mantle eclogites: Inherited from oceanic protoliths, modified during subduction or overprinted during metasomatism?

    NASA Astrophysics Data System (ADS)

    Aulbach, S.; Woodland, A. B.; Vasilyev, P.; Viljoen, F.

    2016-12-01

    Kimberlite-borne mantle eclogite xenoliths of Archaean and Palaeoproterozoic age are commonly interpreted as representing former oceanic crust. As such, they may retain a memory of the redox state of the convecting mantle source that gave rise to their magmatic protoliths and which controls the speciation of volatiles in planetary interiors. Mantle eclogite suites commonly include both cumulate and variably evolved extrusive varieties [1], which may be characterised by initial differences in Fe3+/Fetotal. However, in the warmer ancient mantle, they were also subject to modification due to partial melt loss upon subduction (if a plate tectonic regime existed) and, after capture in the cratonic mantle lithosphere, may be overprinted by interaction with metasomatic melts and fluids. Data are as yet sparse, but new Fe-based oxybarometry shows mantle eclogites to have highly variable fO2 (FMQ-3 to FMQ), whereby low fO2 relative to modern MORB may relate to subduction of more reducing Archaean oceanic crust or loss of ferric Fe during partial melt loss [2,3]. Indeed, using V/Sc as a redox proxy, it was recently shown that Archaean mantle eclogites are more reduced than modern MORB (ΔFMQ-1.3 vs. ΔFMQ -0.4), leading to a shallower depth of redox melting [4]. Although higher Fe contents of eclogites compared to peridotites may translate into greater robustness during metasomatism after emplacement into the cratonic lithosphere, it is possible that this is at least in part responsible for their highly variable Fe-based fO2. In order to help further constrain the redox state of mantle eclogites and unravel the effect of primary and secondary processes, we are currently measuring Fe3+/Fetotal by Mössbauer in garnet from two compositionally well-characterised mantle eclogite suites (Kaapvaal craton and West African craton), with the aim to use recently calibrated oxybarometers [2,3] to calculate fO2. The results will bear on the speciation and hence mobility of carbon during

  15. New Approach in Translational Medicine: Effects of Electrolyzed Reduced Water (ERW) on NF-κB/iNOS Pathway in U937 Cell Line under Altered Redox State

    PubMed Central

    Franceschelli, Sara; Gatta, Daniela Maria Pia; Pesce, Mirko; Ferrone, Alessio; Patruno, Antonia; de Lutiis, Maria Anna; Grilli, Alfredo; Felaco, Mario; Croce, Fausto; Speranza, Lorenza

    2016-01-01

    It is known that increased levels of reactive oxygen species (ROS) and reactive nitrogen species (RNS) can exert harmful effects, altering the cellular redox state. Electrolyzed Reduced Water (ERW) produced near the cathode during water electrolysis exhibits high pH, high concentration of dissolved hydrogen and an extremely negative redox potential. Several findings indicate that ERW had the ability of a scavenger free radical, which results from hydrogen molecules with a high reducing ability and may participate in the redox regulation of cellular function. We investigated the effect of ERW on H2O2-induced U937 damage by evaluating the modulation of redox cellular state. Western blotting and spectrophotometrical analysis showed that ERW inhibited oxidative stress by restoring the antioxidant capacity of superoxide dismutase, catalase and glutathione peroxidase. Consequently, ERW restores the ability of the glutathione reductase to supply the cell of an important endogenous antioxidant, such as GSH, reversing the inhibitory effect of H2O2 on redox balance of U937 cells. Therefore, this means a reduction of cytotoxicity induced by peroxynitrite via a downregulation of the NF-κB/iNOS pathway and could be used as an antioxidant for preventive and therapeutic application. In conclusion, ERW can protect the cellular redox balance, reducing the risk of several diseases with altered cellular homeostasis such as inflammation. PMID:27598129

  16. New Approach in Translational Medicine: Effects of Electrolyzed Reduced Water (ERW) on NF-κB/iNOS Pathway in U937 Cell Line under Altered Redox State.

    PubMed

    Franceschelli, Sara; Gatta, Daniela Maria Pia; Pesce, Mirko; Ferrone, Alessio; Patruno, Antonia; de Lutiis, Maria Anna; Grilli, Alfredo; Felaco, Mario; Croce, Fausto; Speranza, Lorenza

    2016-09-01

    It is known that increased levels of reactive oxygen species (ROS) and reactive nitrogen species (RNS) can exert harmful effects, altering the cellular redox state. Electrolyzed Reduced Water (ERW) produced near the cathode during water electrolysis exhibits high pH, high concentration of dissolved hydrogen and an extremely negative redox potential. Several findings indicate that ERW had the ability of a scavenger free radical, which results from hydrogen molecules with a high reducing ability and may participate in the redox regulation of cellular function. We investigated the effect of ERW on H₂O₂-induced U937 damage by evaluating the modulation of redox cellular state. Western blotting and spectrophotometrical analysis showed that ERW inhibited oxidative stress by restoring the antioxidant capacity of superoxide dismutase, catalase and glutathione peroxidase. Consequently, ERW restores the ability of the glutathione reductase to supply the cell of an important endogenous antioxidant, such as GSH, reversing the inhibitory effect of H₂O₂ on redox balance of U937 cells. Therefore, this means a reduction of cytotoxicity induced by peroxynitrite via a downregulation of the NF-κB/iNOS pathway and could be used as an antioxidant for preventive and therapeutic application. In conclusion, ERW can protect the cellular redox balance, reducing the risk of several diseases with altered cellular homeostasis such as inflammation.

  17. Redox State and Mitochondrial Respiratory Chain Function in Skeletal Muscle of LGMD2A Patients

    PubMed Central

    Nilsson, Mats I.; Macneil, Lauren G.; Kitaoka, Yu; Alqarni, Fatimah; Suri, Rahul; Akhtar, Mahmood; Haikalis, Maria E.; Dhaliwal, Pavneet; Saeed, Munim; Tarnopolsky, Mark A.

    2014-01-01

    Background Calpain-3 deficiency causes oxidative and nitrosative stress-induced damage in skeletal muscle of LGMD2A patients, but mitochondrial respiratory chain function and anti-oxidant levels have not been systematically assessed in this clinical population previously. Methods We identified 14 patients with phenotypes consistent with LGMD2A and performed CAPN3 gene sequencing, CAPN3 expression/autolysis measurements, and in silico predictions of pathogenicity. Oxidative damage, anti-oxidant capacity, and mitochondrial enzyme activities were determined in a subset of muscle biopsies. Results Twenty-one disease-causing variants were detected along the entire CAPN3 gene, five of which were novel (c.338 T>C, c.500 T>C, c.1525-1 G>T, c.2115+4 T>G, c.2366 T>A). Protein- and mRNA-based tests confirmed in silico predictions and the clinical diagnosis in 75% of patients. Reductions in antioxidant defense mechanisms (SOD-1 and NRF-2, but not SOD-2), coupled with increased lipid peroxidation and protein ubiquitination, were observed in calpain-3 deficient muscle, indicating a redox imbalance primarily affecting non-mitochondrial compartments. Although ATP synthase levels were significantly lower in LGMD2A patients, citrate synthase, cytochrome c oxidase, and complex I+III activities were not different from controls. Conclusions Despite significant oxidative damage and redox imbalance in cytosolic/myofibrillar compartments, mitochondrial respiratory chain function is largely maintained in skeletal muscle of LGMD2A patients. PMID:25079074

  18. Shifting redox states of the iron center partitions CDO between crosslink formation or cysteine oxidation.

    PubMed

    Njeri, Catherine W; Ellis, Holly R

    2014-09-15

    Cysteine dioxygenase (CDO) is a mononuclear iron-dependent enzyme that catalyzes the oxidation of L-cysteine to L-cysteine sulfinic acid. The mammalian CDO enzymes contain a thioether crosslink between Cys93 and Tyr157, and purified recombinant CDO exists as a mixture of the crosslinked and non crosslinked isoforms. The current study presents a method of expressing homogenously non crosslinked CDO using a cell permeative metal chelator in order to provide a comprehensive investigation of the non crosslinked and crosslinked isoforms. Electron paramagnetic resonance analysis of purified non crosslinked CDO revealed that the iron was in the EPR silent Fe(II) form. Activity of non crosslinked CDO monitoring dioxygen utilization showed a distinct lag phase, which correlated with crosslink formation. Generation of homogenously crosslinked CDO resulted in an ∼5-fold higher kcat/Km value compared to the enzyme with a heterogenous mixture of crosslinked and non crosslinked CDO isoforms. EPR analysis of homogenously crosslinked CDO revealed that this isoform exists in the Fe(III) form. These studies present a new perspective on the redox properties of the active site iron and demonstrate that a redox switch commits CDO towards either formation of the Cys93-Tyr157 crosslink or oxidation of the cysteine substrate. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Novel Flurometric Tool to Assess Mitochondrial Redox State of Isolated Perfused Rat Lungs After Exposure to Hyperoxia

    PubMed Central

    Audi, Said H.; Staniszewski, Kevin S.; Haworth, Steven T.; Jacobs, Elizabeth R.; Ranji, Mahsa; Zablocki, Clement J.

    2013-01-01

    in mitochondrial redox state of hyperoxic lungs prior to histological changes characteristic of hyperoxia. PMID:25379360

  20. Alteration of the Redox State with Reactive Oxygen Species for 5-Fluorouracil-Induced Oral Mucositis in Hamsters

    PubMed Central

    Wada-Takahashi, Satoko; Takahashi, Shun-suke; Lee, Masaichi Chang-il

    2013-01-01

    Oral mucositis is often induced in patients receiving cancer chemotherapy treatment. It has been reported that oral mucositis can reduce quality of life, as well as increasing the incidence of mortality. The participation of reactive oxygen species (ROS) in the pathogenesis of oral mucositis is well known, but no report has actually demonstrated the presence of ROS. Thus, the purpose of this study was thus to demonstrate the involvement of ROS and the alteration of the redox state in oral mucositis using an in vivo L-band electron spin resonance (ESR) technique. An oral mucositis animal model induced by treatment of 5-fluorouracil with 10% acetic acid in hamster cheek pouch was used. Lipid peroxidation was measured as the level of malondialdehyde determined by the thiobarbituric acid reaction. The rate constants of the signal decay of nitroxyl compounds using in vivo L-band ESR were calculated from the signal decay curves. Firstly, we established the oral mucositis animal model induced by treatment of 5-fluorouracil with acetic acid in hamster cheek pouch. An increased level of lipid peroxidation in oral mucositis was found by measuring malondialdehyde using isolated hamster cheek pouch ulcer. In addition, as a result of in vivo L-band ESR measurements using our model animals, the decay rate constants of carbamoyl-PROXYL, which is a reagent for detecting the redox balance in tissue, were decreased. These results suggest that a redox imbalance might occur by excessive generation of ROS at an early stage of oral mucositis and the consumption of large quantities of antioxidants including glutathione in the locality of oral mucositis. These findings support the presence of ROS involved in the pathogenesis of oral mucositis with anti-cancer therapy, and is useful for the development of novel therapies drugs for oral mucositis. PMID:24376587

  1. Controlling the Charge State and Redox Properties of Supported Polyoxometalates via Soft Landing of Mass Selected Ions

    SciTech Connect

    Gunaratne, Kalupathirannehelage Don D.; Johnson, Grant E.; Andersen, Amity; Du, Dan; Zhang, Weiying; Prabhakaran, Venkateshkumar; Lin, Yuehe; Laskin, Julia

    2014-12-04

    We investigate the controlled deposition of Keggin polyoxometalate (POM) anions, PMo12O403- and PMo12O402-, onto different self-assembled monolayer (SAM) surfaces via soft landing of mass-selected ions. Utilizing in situ infrared reflection absorption spectroscopy (IRRAS), ex situ cyclic voltammetry (CV) and electronic structure calculations, we examine the structure and charge retention of supported multiply-charged POM anions and characterize the redox properties of the modified surfaces. SAMs of alkylthiol (HSAM), perfluorinated alkylthiol (FSAM), and alkylthiol terminated with NH3+ functional groups (NH3+SAM) are chosen as model substrates for soft landing to examine the factors which influence the immobilization and charge retention of multiply charged anionic molecules. The distribution of charge states of POMs on different SAM surfaces are determined by comparing the IRRAS spectra with vibrational spectra calculated using density functional theory (DFT). In contrast to the results obtained previously for multiply charged cations, soft landed anions are found to retain charge on all three SAM surfaces. This charge retention is attributed to the substantial electron binding energy of the POM anions. Investigation of redox properties by CV reveals that, while surfaces prepared by soft landing exhibit similar features to those prepared by adsorption of POM from solution, the soft landed POM2- has a pronounced shift in oxidation potential compared to POM3- for one of the redox couples. These results demonstrate that ion soft landing is uniquely suited for precisely controlled preparation of substrates with specific electronic and chemical properties that cannot be achieved using conventional deposition techniques.

  2. Redox regulation: an introduction.

    PubMed

    Dietz, Karl-Josef; Scheibe, Renate

    2004-01-01

    The redox-state is a critical determinate of cell function, and any major imbalances can cause severe damage or death. The cellular redox status therefore needs to be sensed and modulated before such imbalances occur. Various redox-active components are involved in these processes, including thioredoxins, glutaredoxins and other thiol/disulphide-containing proteins. The cellular reactions for cytoprotection and for signalling are integrated with physiological redox-reactions in photosynthesis, assimilation and respiration. They also determine the developmental fate of the cell and finally decide on proliferation or cell death. An international workshop on redox regulation, organized by the research initiative FOR 387 of the Deutsche Forschungsgemeinschaft, was held in Bielefeld, Germany in 2002. A selection of articles originating from the meeting is printed in this issue of Physiologia Plantarum.

  3. Changes in phosphorylation of adenosine phosphate and redox state of nicotinamide-adenine dinucleotide (phosphate) in Geobacter sulfurreducens in response to electron acceptor and anode potential variation.

    PubMed

    Rose, Nicholas D; Regan, John M

    2015-12-01

    Geobacter sulfurreducens is one of the dominant bacterial species found in biofilms growing on anodes in bioelectrochemical systems. The intracellular concentrations of reduced and oxidized forms of nicotinamide-adenine dinucleotide (NADH and NAD(+), respectively) and nicotinamide-adenine dinucleotide phosphate (NADPH and NADP(+), respectively) as well as adenosine triphosphate (ATP), adenosine diphosphate (ADP), and adenosine monophosphate (AMP) were measured in G. sulfurreducens using fumarate, Fe(III)-citrate, or anodes poised at different potentials (110, 10, -90, and -190 mV (vs. SHE)) as the electron acceptor. The ratios of CNADH/CNAD+ (0.088±0.022) and CNADPH/CNADP+ (0.268±0.098) were similar under all anode potentials tested and with Fe(III)-citrate (reduced extracellularly). Both ratios significantly increased with fumarate as the electron acceptor (0.331±0.094 for NAD and 1.96±0.37 for NADP). The adenylate energy charge (the fraction of phosphorylation in intracellular adenosine phosphates) was maintained near 0.47 under almost all conditions. Anode-growing biofilms demonstrated a significantly higher molar ratio of ATP/ADP relative to suspended cultures grown on fumarate or Fe(III)-citrate. These results provide evidence that the cellular location of reduction and not the redox potential of the electron acceptor controls the intracellular redox potential in G. sulfurreducens and that biofilm growth alters adenylate phosphorylation.

  4. Redox Regulation of Mitochondrial Function

    PubMed Central

    Handy, Diane E.

    2012-01-01

    Abstract Redox-dependent processes influence most cellular functions, such as differentiation, proliferation, and apoptosis. Mitochondria are at the center of these processes, as mitochondria both generate reactive oxygen species (ROS) that drive redox-sensitive events and respond to ROS-mediated changes in the cellular redox state. In this review, we examine the regulation of cellular ROS, their modes of production and removal, and the redox-sensitive targets that are modified by their flux. In particular, we focus on the actions of redox-sensitive targets that alter mitochondrial function and the role of these redox modifications on metabolism, mitochondrial biogenesis, receptor-mediated signaling, and apoptotic pathways. We also consider the role of mitochondria in modulating these pathways, and discuss how redox-dependent events may contribute to pathobiology by altering mitochondrial function. Antioxid. Redox Signal. 16, 1323–1367. PMID:22146081

  5. A reversible early oxidized redox state that precedes macromolecular ROS damage in aging non-transgenic and 3xTg-AD mouse neurons

    PubMed Central

    Ghosh, D.; LeVault, K.; Barnett, A.; Brewer, G.J.

    2012-01-01

    The brain depends on redox electrons from NADH to produce ATP and oxyradicals (ROS). Since ROS damage and mitochondrial dysregulation are prominent in aging and Alzheimer’s disease (AD) and their relationship to redox state is unclear, we wanted to know whether an oxidative redox shift precedes these markers and leads to macromolecular damage in a mouse model of AD. We used the 3xTg-AD mouse model that displays cognitive deficits beginning at 4 months. Hippocampal/cortical neurons were isolated across the age-span and cultured in common nutrients to control for possible hormonal and vascular differences. We found an increase of NAD(P)H levels and redox state in non-transgenic neurons until middle age, followed by a decline in old age. The 3xTg-AD neurons maintained much lower resting NAD(P)H and redox state after 4 months, but the NADH regenerating capacity continuously declined with age beginning at 2 months. These redox characteristics were partially reversible with nicotinamide, a biosynthetic precursor of NAD+. Nicotinamide also protected against glutamate excitotoxicity. Compared to non-transgenic neurons, 3xTg-AD neurons possessed more mitochondria/neuron and lower glutathione levels which preceeded age-related increases in ROS levels. These glutathione deficits were again reversible with nicotinamide in 3xTg-AD neurons. Surprisingly, low macromolecular ROS damage was only elevated after 4 months in the 3xTg-AD neurons if anti-oxidants were removed. The present data suggest that a more oxidized redox state and a lower antioxidant glutathione defense can be dissociated from neuronal ROS damage, changes that precede the onset of cognitive deficits in the 3xTg-AD model. PMID:22539844

  6. The effects of temperature, pH and redox state on the stability of glutamic acid in hydrothermal fluids

    NASA Astrophysics Data System (ADS)

    Lee, Namhey; Foustoukos, Dionysis I.; Sverjensky, Dimitri A.; Cody, George D.; Hazen, Robert M.

    2014-06-01

    Natural hydrothermal vent environments cover a wide range of physicochemical conditions involving temperature, pH and redox state. The stability of simple biomolecules such as amino acids in such environments is of interest in various fields of study from the origin of life to the metabolism of microbes at the present day. Numerous previous experimental studies have suggested that amino acids are unstable under hydrothermal conditions and decompose rapidly. However, previous studies have not effectively controlled the redox state of the hydrothermal fluids. Here we studied the stability of glutamate with and without reducing hydrothermal conditions imposed by 13 mM aqueous H2 at temperatures of 150, 200 and 250 °C and initial (25 °C) pH values of 6 and 10 in a flow-through hydrothermal reactor with reaction times from 3 to 36 min. We combined the experimental measurements with theoretical calculations to model the in situ aqueous speciation and pH values. As previously observed under hydrothermal conditions, the main reaction involves glutamate cyclizing to pyroglutamate through a simple dehydration reaction. However, the amounts of decomposition products of the glutamate detected, including succinate, formate, carbon dioxide and ammonia depend on the temperature, the pH and particularly the redox state of the fluid. In the absence of dissolved H2, glutamate decomposes in the sequence glutamate, glutaconate, α-hydroxyglutarate, ketoglutarate, formate and succinate, and ultimately to CO2 and micromolar quantities of H2(aq). Model speciation calculations indicate the CO2, formate and H2(aq) are not in metastable thermodynamic equilibrium. However, with 13 mM H2(aq) concentrations, the amounts of decomposition products are suppressed at all temperatures and pH values investigated. The small amounts of CO2 and formate present are calculated to be in metastable equilibrium with the H2. It is further proposed that there is a metastable equilibrium between glutamate

  7. Relationships between the Efficiencies of Photosystems I and II and Stromal Redox State in CO2-Free Air 1

    PubMed Central

    Harbinson, Jeremy; Foyer, Christine H.

    1991-01-01

    The responses of the efficiencies of photosystems I and II, stromal redox state (as indicated by NADP-malate dehydrogenase activation state), and activation of the Benson-Calvin cycle enzymes ribulose 1,5-bisphosphate carboxylase and fructose 1,6-bisphosphatase to varying irradiance were measured in pea (Pisum sativum L.) leaves operating close to the CO2 compensation point. A comparison of the relationships among these parameters obtained from leaves in air was made with those obtained when the leaves were maintained in air from which the CO2 had been removed. P700 was more oxidized at any measured irradiance in CO2-free air than in air. The relationship between the quantum efficiencies of the photosystems in CO2-free air was distinctly curvilinear in contrast to the predominantly linear relationship obtained with leaves in air. This nonlinearity may be consistent with the operation of cyclic electron flow around photosystem I because the quantum efficiency of photosystem II was much more restricted than the quantum efficiency of photosystem I. In CO2-free air, measured NADP-malate dehydrogenase activities varied considerably at low irradiances. However, at high irradiance the activity of the enzyme was low, implying that the stroma was oxidized. In contrast, fructose-1,6-bisphosphatase activities tended to increase with increasing electron flux through the photosystems. Ribulose-1,5-bisphosphate carboxylase activity remained relatively constant with respect to irradiance in CO2-free air, with an activation state 50% of maximum. We conclude that, at the CO2 compensation point and high irradiance, low redox states are favored and that cyclic electron flow may be substantial. These two features may be the requirements necessary to trigger and maintain the dissipative processes in the thylakoid membrane. PMID:16668401

  8. Cu/ZnO nanocatalysts in response to environmental conditions: surface morphology, electronic structure, redox state and CO2 activation.

    PubMed

    Martínez-Suárez, Luis; Frenzel, Johannes; Marx, Dominik

    2014-12-21

    Methanol synthesis is one of the landmarks of heterogeneous catalysis due to the great industrial significance of methanol as a clean liquid fuel and as a raw material for industry. Understanding in atomistic detail the properties of the underlying metal/oxide catalyst materials as a function of temperature and composition of the reactive gas phase is of utmost importance in order to eventually improve the production process. By performing extensive density functional theory based slab calculations in combination with a thermodynamic formalism we establish an atomistic understanding of gas phase-induced changes of surface morphology, redox properties and reactivity of ZnO supported Cu nanocatalysts. Extending our recent insights [Phys. Rev. Lett., 2013, 110, 086108], we explore surface stabilization mechanisms and site-dependent redox states of both catalyst components as well as the pronounced electronic charge transfer processes across the metal-support interface. Moreover, ab initio molecular dynamics simulations unveil the vital role played by dynamical shape fluctuations of the deposited Cu8 cluster. The pronounced structural flexibility of the metal nanoparticle is found to enhance CO2 activation over Cu8 at the elevated temperature conditions of the industrial methanol synthesis process, in addition to activation of CO2via electronic charge transfer from the ZnO support.

  9. Crystal structure of pentaerythritol tetranitrate reductase: "flipped" binding geometries for steroid substrates in different redox states of the enzyme.

    PubMed

    Barna, T M; Khan, H; Bruce, N C; Barsukov, I; Scrutton, N S; Moody, P C

    2001-07-06

    Pentaerythritol tetranitrate reductase (PETN reductase) degrades high explosive molecules including nitrate esters, nitroaromatics and cyclic triazine compounds. The enzyme also binds a variety of cyclic enones, including steroids; some steroids act as substrates whilst others are inhibitors. Understanding the basis of reactivity with cyclic enones requires structural information for the enzyme and key complexes formed with steroid substrates and inhibitors. The crystal structure of oxidised and reduced PETN reductase at 1.5 A resolution establishes a close structural similarity to the beta/alpha-barrel flavoenzyme, old yellow enzyme. In complexes of oxidised PETN reductase with progesterone (an inhibitor), 1,4-androstadiene-3,17-dione and prednisone (both substrates) the steroids are stacked over the si-face of the flavin in an orientation different from that reported for old yellow enzyme. The specifically reducible 1,2 unsaturated bonds in 1,4-androstadiene-3,17-dione and prednisone are not optimally aligned with the flavin N5 in oxidised enzyme complexes. These structures suggest either relative "flipping" or shifting of the steroid with respect to the flavin when bound in different redox forms of the enzyme. Deuterium transfer from nicotinamide coenzyme to 1,4-androstadiene-3,17-dione via the enzyme bound FMN indicates 1alpha addition at the steroid C2 atom. These studies rule out lateral motion of the steroid and indicate that the steroid orientation is "flipped" in different redox states of the enzyme. Copyright 2001 Academic Press.

  10. Vanadium solid-salt battery: Solid state with two redox couples

    NASA Astrophysics Data System (ADS)

    Yamamura, Tomoo; Wu, Xiongwei; Ohta, Suguru; Shirasaki, Kenji; Sakuraba, Hiroki; Satoh, Isamu; Shikama, Tatsuo

    We present the "vanadium solid-salt battery" (VSSB), which has high energy density, is low cost, is easily recycled, operates at ambient temperature, and has no requirement for special solvents. The VSSB contains two types of vanadium solid salts that are supported on carbon felts with a minimal amount of hydrosulfuric acid added to moisten the ion-exchange membrane. The optimized VSSB shows a cell potential of 1.34 V, excellent reproducibility for charging and discharging for nearly 100 cycles, a high energy efficiency (87%) and a high energy density (77 W h kg -1 at 5 mA cm -2 using the carbon felt XF208). The energy density is enhanced by 250-350% compared with conventional vanadium redox-flow batteries.

  11. Exploring Redox States, Doping and Ordering of Electroactive Star-Shaped Oligo(aniline)s.

    PubMed

    Mills, Benjamin M; Fey, Natalie; Marszalek, Tomasz; Pisula, Wojciech; Rannou, Patrice; Faul, Charl F J

    2016-11-14

    We have prepared a simple star-shaped oligo(aniline) (TDPB) and characterised it in detail by MALDI-TOF MS, UV/Vis/NIR spectroscopy, time-dependent DFT, cyclic voltammetry and EPR spectroscopy. TDPB is part of an underdeveloped class of π-conjugated molecules with great potential for organic electronics, display and sensor applications. It is redox active and reacts with acids to form radical cations. Acid-doped TDPB shows behaviour similar to discotic liquid crystals, with X-ray scattering investigations revealing columnar self-assembled arrays. The combination of unpaired electrons and supramolecular stacking suggests that star-shaped oligo(aniline)s like TDPB have the potential to form conducting nanowires and organic magnetic materials.

  12. Exploring Redox States, Doping and Ordering of Electroactive Star‐Shaped Oligo(aniline)s

    PubMed Central

    Mills, Benjamin M.; Fey, Natalie; Marszalek, Tomasz; Pisula, Wojciech; Rannou, Patrice

    2016-01-01

    Abstract We have prepared a simple star‐shaped oligo(aniline) (TDPB) and characterised it in detail by MALDI‐TOF MS, UV/Vis/NIR spectroscopy, time‐dependent DFT, cyclic voltammetry and EPR spectroscopy. TDPB is part of an underdeveloped class of π‐conjugated molecules with great potential for organic electronics, display and sensor applications. It is redox active and reacts with acids to form radical cations. Acid‐doped TDPB shows behaviour similar to discotic liquid crystals, with X‐ray scattering investigations revealing columnar self‐assembled arrays. The combination of unpaired electrons and supramolecular stacking suggests that star‐shaped oligo(aniline)s like TDPB have the potential to form conducting nanowires and organic magnetic materials. PMID:27723154

  13. Statins as Regulators of Redox State in the Vascular Endothelium: Beyond Lipid Lowering

    PubMed Central

    Margaritis, Marios; Channon, Keith M.

    2014-01-01

    Abstract Significance: Endothelial dysfunction and the imbalance between nitric oxide (NO) and reactive oxygen species production in the vascular endothelium are important early steps in atherogenesis, a major socioeconomic health problem. Statins have well-established roles in primary and secondary prevention of cardiovascular disease (CVD), due to both their lipid-lowering capacity and their pleiotropic properties. It is therefore important to understand the mechanisms by which statins can modify endothelial function and affect atherogenesis. Recent Advances: In the last decade, the concept of statin pleiotropy has been reinforced by a large number of cell culture, animal, and translational studies. Statins have been shown to suppress the activity of pro-oxidant enzymes (such as NADPH oxidase) and pro-inflammatory transcriptional pathways in the endothelium. At the same time, they enhance endothelial NO synthase expression and activity while they also improve its enzymatic coupling. This leads to increased NO bioavailability and improved endothelial function. Critical Issues: Despite significant recent advances, the exact mechanisms of statin pleitropy are still only partially understood. The vast majority of the published literature relies on animal studies, while the actual mechanistic studies in humans are limited. Future Directions: The success of statins as endothelium redox-modifying agents with a direct impact on clinical outcome highlights the importance of the endothelium as a therapeutic target in CVD. Better understanding of the mechanisms that underlie endothelial dysfunction could lead to the design of novel therapeutic strategies that target the vascular endothelium for the prevention and treatment of CVD. Antioxid. Redox Signal. 20, 1198–1215. PMID:24111702

  14. Decrease in age-related tau hyperphosphorylation and cognitive improvement following vitamin D supplementation are associated with modulation of brain energy metabolism and redox state.

    PubMed

    Briones, T L; Darwish, H

    2014-03-14

    In the present study we examined whether vitamin D supplementation can reduce age-related tau hyperphosphorylation and cognitive impairment by enhancing brain energy homeostasis and protein phosphatase 2A (PP2A) activity, and modulating the redox state. Male F344 rats aged 20 months (aged) and 6 months (young) were randomly assigned to either vitamin D supplementation or no supplementation (control). Rats were housed in pairs and the supplementation group (n=10 young and n=10 aged) received subcutaneous injections of vitamin D (1, α25-dihydroxyvitamin D3) for 21 days. Control animals (n=10 young and n=10 aged) received equal volume of normal saline and behavioral testing in the water maze started on day 14 after the initiation of vitamin D supplementation. Tau phosphorylation, markers of brain energy metabolism (ADP/ATP ratio and adenosine monophosphate-activated protein kinase) and redox state (levels of reactive oxygen species, activity of superoxide dismutase, and glutathione levels) as well as PP2A activity were measured in hippocampal tissues. Our results extended previous findings that: (1) tau phosphorylation significantly increased during aging; (2) markers of brain energy metabolism and redox state are significantly decreased in aging; and (3) aged rats demonstrated significant learning and memory impairment. More importantly, we found that age-related changes in brain energy metabolism, redox state, and cognitive function were attenuated by vitamin D supplementation. No significant differences were seen in tau hyperphosphorylation, markers of energy metabolism and redox state in the young animal groups. Our data suggest that vitamin D ameliorated the age-related tau hyperphosphorylation and cognitive decline by enhancing brain energy metabolism, redox state, and PP2A activity making it a potentially useful therapeutic option to alleviate the effects of aging. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  15. Isochorismate synthase 1 is required for thylakoid organization, optimal plastoquinone redox status, and state transitions in Arabidopsis thaliana

    PubMed Central

    Gawroński, Piotr; Górecka, Magdalena; Bederska, Magdalena; Rusaczonek, Anna; Ślesak, Ireneusz; Kruk, Jerzy; Karpiński, Stanisław

    2013-01-01

    Isochorismate synthase 1 (ICS1) is a crucial enzyme in the salicylic acid (SA) synthesis pathway, and thus it is important for immune defences. The ics1 mutant is used in experiments on plant–pathogen interactions, and ICS1 is required for the appropriate hypersensitive disease defence response. However, ICS1 also takes part in the synthesis of phylloquinone, which is incorporated into photosystem I and is an important component of photosynthetic electron transport in plants. Therefore, photosynthetic and molecular analysis of the ics1 mutant in comparison with wild-type and SA-degrading transgenic NahG Arabidopsis thaliana plants was performed. Photosynthetic parameters in the ics1 mutant, when compared with the wild type, were changed in a manner observed previously for state transition-impaired plants (STN7 kinase recessive mutant, stn7). In contrast to stn7, deregulation of the redox status of the plastoquinone pool (measured as 1–q p) in ics1 showed significant variation depending on the leaf age. SA-degrading transgenic NahG plants targeted to the cytoplasm or chloroplasts displayed normal (wild-type-like) state transition. However, ics1 plants treated with a phylloquinone precursor displayed symptoms of phenotypic reversion towards the wild type. ics1 also showed altered thylakoid structure with an increased number of stacked thylakoids per granum which indicates the role of ICS1 in regulation of state transition. The results presented here suggest the role of ICS1 in integration of the chloroplast ultrastructure, the redox status of the plastoquinone pool, and organization of the photosystems, which all are important for optimal immune defence and light acclimatory responses. PMID:23956412

  16. Modulation of the matrix redox signaling by mitochondrial Ca(2.).

    PubMed

    Santo-Domingo, Jaime; Wiederkehr, Andreas; De Marchi, Umberto

    2015-11-26

    Mitochondria sense, shape and integrate signals, and thus function as central players in cellular signal transduction. Ca(2+) waves and redox reactions are two such intracellular signals modulated by mitochondria. Mitochondrial Ca(2+) transport is of utmost physio-pathological relevance with a strong impact on metabolism and cell fate. Despite its importance, the molecular nature of the proteins involved in mitochondrial Ca(2+) transport has been revealed only recently. Mitochondrial Ca(2+) promotes energy metabolism through the activation of matrix dehydrogenases and down-stream stimulation of the respiratory chain. These changes also alter the mitochondrial NAD(P)H/NAD(P)(+) ratio, but at the same time will increase reactive oxygen species (ROS) production. Reducing equivalents and ROS are having opposite effects on the mitochondrial redox state, which are hard to dissect. With the recent development of genetically encoded mitochondrial-targeted redox-sensitive sensors, real-time monitoring of matrix thiol redox dynamics has become possible. The discoveries of the molecular nature of mitochondrial transporters of Ca(2+) combined with the utilization of the novel redox sensors is shedding light on the complex relation between mitochondrial Ca(2+) and redox signals and their impact on cell function. In this review, we describe mitochondrial Ca(2+) handling, focusing on a number of newly identified proteins involved in mitochondrial Ca(2+) uptake and release. We further discuss our recent findings, revealing how mitochondrial Ca(2+) influences the matrix redox state. As a result, mitochondrial Ca(2+) is able to modulate the many mitochondrial redox-regulated processes linked to normal physiology and disease.

  17. Fundamentally Addressing Bromine Storage through Reversible Solid-State Confinement in Porous Carbon Electrodes: Design of a High-Performance Dual-Redox Electrochemical Capacitor.

    PubMed

    Yoo, Seung Joon; Evanko, Brian; Wang, Xingfeng; Romelczyk, Monica; Taylor, Aidan; Ji, Xiulei; Boettcher, Shannon W; Stucky, Galen D

    2017-07-26

    Research in electric double-layer capacitors (EDLCs) and rechargeable batteries is converging to target systems that have battery-level energy density and capacitor-level cycling stability and power density. This research direction has been facilitated by the use of redox-active electrolytes that add faradaic charge storage to increase energy density of the EDLCs. Aqueous redox-enhanced electrochemical capacitors (redox ECs) have, however, performed poorly due to cross-diffusion of soluble redox couples, reduced cycle life, and low operating voltages. In this manuscript, we propose that these challenges can be simultaneously met by mechanistically designing a liquid-to-solid phase transition of oxidized catholyte (or reduced anolyte) with confinement in the pores of electrodes. Here we demonstrate the realization of this approach with the use of bromide catholyte and tetrabutylammonium cation that induces reversible solid-state complexation of Br2/Br3(-). This mechanism solves the inherent cross-diffusion issue of redox ECs and has the added benefit of greatly stabilizing the reactive bromine generated during charging. Based on this new mechanistic insight on the utilization of solid-state bromine storage in redox ECs, we developed a dual-redox EC consisting of a bromide catholyte and an ethyl viologen anolyte with the addition of tetrabutylammonium bromide. In comparison to aqueous and organic electric double-layer capacitors, this system enhances energy by factors of ca. 11 and 3.5, respectively, with a specific energy of ∼64 W·h/kg at 1 A/g, a maximum power density >3 kW/kg, and cycling stability over 7000 cycles.

  18. Accurate predictions of iron redox state in silicate glasses: A multivariate approach using X-ray absorption spectroscopy

    SciTech Connect

    Dyar, M. Darby; McCanta, Molly; Breves, Elly; Carey, C. J.; Lanzirotti, Antonio

    2016-03-01

    Pre-edge features in the K absorption edge of X-ray absorption spectra are commonly used to predict Fe3+ valence state in silicate glasses. However, this study shows that using the entire spectral region from the pre-edge into the extended X-ray absorption fine-structure region provides more accurate results when combined with multivariate analysis techniques. The least absolute shrinkage and selection operator (lasso) regression technique yields %Fe3+ values that are accurate to ±3.6% absolute when the full spectral region is employed. This method can be used across a broad range of glass compositions, is easily automated, and is demonstrated to yield accurate results from different synchrotrons. It will enable future studies involving X-ray mapping of redox gradients on standard thin sections at 1 × 1 μm pixel sizes.

  19. Accurate predictions of iron redox state in silicate glasses: A multivariate approach using X-ray absorption spectroscopy

    SciTech Connect

    Dyar, M. Darby; McCanta, Molly; Breves, Elly; Carey, C. J.; Lanzirotti, Antonio

    2016-03-01

    Pre-edge features in the K absorption edge of X-ray absorption spectra are commonly used to predict Fe3+ valence state in silicate glasses. However, this study shows that using the entire spectral region from the pre-edge into the extended X-ray absorption fine-structure region provides more accurate results when combined with multivariate analysis techniques. The least absolute shrinkage and selection operator (lasso) regression technique yields %Fe3+ values that are accurate to ±3.6% absolute when the full spectral region is employed. This method can be used across a broad range of glass compositions, is easily automated, and is demonstrated to yield accurate results from different synchrotrons. It will enable future studies involving X-ray mapping of redox gradients on standard thin sections at 1 × 1 μm pixel sizes.

  20. Real-time assays for monitoring the influence of sulfide and sulfane sulfur species on protein thiol redox states.

    PubMed

    Greiner, Romy; Dick, Tobias P

    2015-01-01

    Hydrogen sulfide (H2S) is known to induce persulfidation of protein thiols. However, the process of H2S-induced persulfidation is not fully understood as it requires an additional oxidant. There are several mechanistic possibilities and it is of interest to determine which pathway is kinetically most relevant. Here, we detail in vitro assays for the real-time monitoring of thiol redox states in two model proteins with oxidizable cysteines, PTEN, and roGFP2. These allow kinetic measurements of the response of defined protein thiols (or disulfides) to sulfide and sulfane sulfur species. The combination of these assays with cold cyanolysis reveals the role of intermediary sulfane sulfur species in H2S-induced protein thiol oxidation.

  1. Intra-cardiac Light Catheter for Transmural Absorbance Spectroscopy of Perfused Myocardium: Measurement of Myoglobin Oxygenation and Mitochondria Redox State.

    PubMed

    Femnou, Armel N; Kuzmiak-Glancy, Sarah; Covian, Raul; Giles, Abigail V; Kay, Matthew W; Balaban, Robert S

    2017-09-22

    Absorbance spectroscopy of intrinsic cardiac chromophores provides non-destructive assessment of cytosolic oxygenation and mitochondria redox state. Isolated perfused heart spectroscopy is usually conducted by collecting reflected light from the heart surface, which represents a combination of surface scattering events and light that traversed portions of the myocardium. Reflectance spectroscopy with complex surface scattering effects in the beating heart leads to difficulty in quantitating chromophore absorbance. In this study, surface scattering was minimized and transmural path length optimized by placing a light source within the left ventricle (LV) chamber while monitoring transmurally transmitted light at the epicardial surface. The custom designed intra-chamber light catheter was a flexible coaxial cable (2.42 French) terminated with an encapsulated side firing Light Emitting Diode (LED) of 1.8×0.8 mm, altogether similar in size to a Millar pressure catheter. The LED catheter had minimal impact on aortic flow and heart rate in Langendorff perfusion and did not impact stability of the LV working heart. Changes in transmural absorbance spectra were deconvoluted using a library of chromophore reference spectra to quantify the relative contribution of specific chromophores to the changes in measured absorbance. This broad band spectral deconvolution approach eliminated errors that may result from simple dual wavelength absorbance intensity. Myoglobin oxygenation level was only 82.2±3.0%, while cytochrome c and cytochrome a+a3 were 13.3±1.4% and 12.6±2.2% reduced, respectively, in Langendorff perfused heart. The intra-cardiac illumination strategy permits transmural optical absorbance spectroscopy in perfused hearts which provides a non-invasive real-time monitor of cytosolic oxygenation and mitochondria redox state. Copyright © 2017, American Journal of Physiology-Heart and Circulatory Physiology.

  2. Real-Time Measurements of the Redox States of c-Type Cytochromes in Electroactive Biofilms: A Confocal Resonance Raman Microscopy Study

    PubMed Central

    Virdis, Bernardino; Millo, Diego; Donose, Bogdan C.; Batstone, Damien J.

    2014-01-01

    Confocal Resonance Raman Microscopy (CRRM) was used to probe variations of redox state of c-type cytochromes embedded in living mixed-culture electroactive biofilms exposed to different electrode polarizations, under potentiostatic and potentiodynamic conditions. In the absence of the metabolic substrate acetate, the redox state of cytochromes followed the application of reducing and oxidizing electrode potentials. Real-time monitoring of the redox state of cytochromes during cyclic voltammetry (CV) in a potential window where cytochromes reduction occurs, evidenced a measurable time delay between the oxidation of redox cofactors probed by CV at the electrode interface, and oxidation of distal cytochromes probed by CRRM. This delay was used to tentatively estimate the diffusivity of electrons through the biofilm. In the presence of acetate, the resonance Raman spectra of young (10 days, j = 208±49 µA cm−2) and mature (57 days, j = 267±73 µA cm−2) biofilms show that cytochromes remained oxidized homogeneously even at layers as far as 70 µm from the electrode, implying the existence of slow metabolic kinetics that do not result in the formation of a redox gradient inside the biofilm during anode respiration. However, old biofilms (80 days, j = 190±37 µA cm−2) with thickness above 100 µm were characterized by reduced catalytic activity compared to the previous developing stages. The cytochromes in these biofilm were mainly in the reduced redox state, showing that only aged mixed-culture biofilms accumulate electrons during anode respiration. These results differ substantially from recent observations in pure Geobacter sulfurreducens electroactive biofilms, in which accumulation of reduced cytochromes is already observed in thinner biofilms, thus suggesting different bottlenecks in current production for mixed-culture and G. sulfurreducens biofilms. PMID:24587123

  3. Real-time measurements of the redox states of c-type cytochromes in electroactive biofilms: a confocal resonance Raman Microscopy study.

    PubMed

    Virdis, Bernardino; Millo, Diego; Donose, Bogdan C; Batstone, Damien J

    2014-01-01

    Confocal Resonance Raman Microscopy (CRRM) was used to probe variations of redox state of c-type cytochromes embedded in living mixed-culture electroactive biofilms exposed to different electrode polarizations, under potentiostatic and potentiodynamic conditions. In the absence of the metabolic substrate acetate, the redox state of cytochromes followed the application of reducing and oxidizing electrode potentials. Real-time monitoring of the redox state of cytochromes during cyclic voltammetry (CV) in a potential window where cytochromes reduction occurs, evidenced a measurable time delay between the oxidation of redox cofactors probed by CV at the electrode interface, and oxidation of distal cytochromes probed by CRRM. This delay was used to tentatively estimate the diffusivity of electrons through the biofilm. In the presence of acetate, the resonance Raman spectra of young (10 days, j = 208 ± 49 µA cm(-2)) and mature (57 days, j = 267 ± 73 µA cm(-2)) biofilms show that cytochromes remained oxidized homogeneously even at layers as far as 70 µm from the electrode, implying the existence of slow metabolic kinetics that do not result in the formation of a redox gradient inside the biofilm during anode respiration. However, old biofilms (80 days, j = 190 ± 37 µA cm(-2)) with thickness above 100 µm were characterized by reduced catalytic activity compared to the previous developing stages. The cytochromes in these biofilm were mainly in the reduced redox state, showing that only aged mixed-culture biofilms accumulate electrons during anode respiration. These results differ substantially from recent observations in pure Geobacter sulfurreducens electroactive biofilms, in which accumulation of reduced cytochromes is already observed in thinner biofilms, thus suggesting different bottlenecks in current production for mixed-culture and G. sulfurreducens biofilms.

  4. Single sample extraction protocol for the quantification of NAD and NADH redox states in Saccharomyces cerevisiae

    PubMed Central

    Sporty, Jennifer L.; Kabir, Md. Mohiuddin; Turteltaub, Kenneth W.; Ognibene, Ted; Lin, Su-Ju; Bench, Graham

    2009-01-01

    A robust redox extraction protocol for quantitative and reproducible metabolite isolation and recovery has been developed for simultaneous measurement of nicotin-amide adenine dinucleotide (NAD) and its reduced form, NADH, from Saccharomyces cerevisiae. Following culture in liquid media, yeast cells were harvested by centrifugation and then lysed under nonoxidizing conditions by bead blasting in ice-cold, nitrogen-saturated 50 mM ammonium acetate. To enable protein denaturation, ice cold nitrogen-saturated CH3CN/50 mM ammonium acetate (3:1 v/v) was added to the cell lysates. Chloroform extractions were performed on supernatants to remove organic solvent. Samples were lyophilized and resuspended in 50 mM ammonium acetate. NAD and NADH were separated by HPLC and quantified using UV–Vis absorbance detection. NAD and NADH levels were evaluated in yeast grown under normal (2% glucose) and calorie restricted (0.5% glucose) conditions. Results demonstrate that it is possible to perform a single preparation to reliably and robustly quantitate both NAD and NADH contents in the same sample. Robustness of the protocol suggests it will be (i) applicable to quantification of these metabolites in other cell cultures; and (ii) amenable to isotope labeling strategies to determine the relative contribution of specific metabolic pathways to total NAD and NADH levels in cell cultures. PMID:18763242

  5. Bioflavonoid effects on the mitochondrial respiratory electron transport chain and cytochrome c redox state.

    PubMed

    Moini, H; Arroyo, A; Vaya, J; Packer, L

    1999-01-01

    The polyphenolic structure common to flavonoids enables them to donate electrons and exert antioxidant activity. Since the mitochondrial electron transport chain consists of a series of redox intermediates, the effect of flavonoids in a complex mixture of polyphenols, as well as related pure flavonoids, was evaluated on the rat liver mitochondrial electron transport chain. A French maritime pine bark extract (PBE), a complex mixture of polyphenols and related pure flavonoids, was able to reduce cytochrome c reversibly, possibly by donation of electrons to the iron of the heme group; the donated electrons can be utilized by cytochrome c oxidase. Among single flavonoids tested, (-)-epicatechin gallate had the greatest ability to reduce cytochrome c. In addition, PBE competitively inhibited electron chain activity in both whole mitochondria and submitochondrial particles. A 3.5-fold increase in the apparent Km value for succinate was calculated from reciprocal plots. Among the flavonoids tested, taxifolin and (-)-epicatechin gallate showed minor inhibitory effects, while (+/-)-catechin and (+)-epicatechin were ineffective. Activities of NADH-ubiquinone, succinate-ubiquinone, and ubiquinol-cytochrome c reductases were inhibited by low concentrations of PBE to a similar extent. However, inhibition of cytochrome c oxidase activity required 4-fold higher PBE concentrations. These results suggest that flavonoids reduce cytochrome c and that PBE inhibits electron transport chain activity mainly through NADH-ubiquinone, succinate-ubiquinone, and ubiquinol-cytochrome c reductases.

  6. Effects of Moderate Aerobic Exercise on Cognitive Abilities and Redox State Biomarkers in Older Adults.

    PubMed

    Alghadir, Ahmad H; Gabr, Sami A; Al-Eisa, Einas S

    2016-01-01

    We used a moderate aerobic exercise program for 24 weeks to measure the positive impact of physical activity on oxidative stress and inflammatory markers and its association with cognitive performance in healthy older adults. A total of 100 healthy subjects (65-95 Yrs) were randomly classified into two groups: control group (n = 50) and exercise group (n = 50). Cognitive functioning, physical activity score, MDA, 8-OHdG, TAC, and hs-CRP were assessed using LOTCA battery, prevalidated PA questionnaire, and immunoassay techniques. LOTCA 7-set scores of cognitive performance showed a significant correlation with physical activity status and the regulation of both oxidative stress free radicals and inflammatory markers in all older subjects following 24 weeks of moderate exercise. Physically active persons showed a higher cognitive performance along with reduction in the levels of MDA, 8-OHdG, and hs-CRP and increase in TAC activity compared with sedentary participants. Cognitive performance correlated positively with the increase in TAC activity and physical fitness scores and negatively with MDA, 8-OHdG, and hs-CRP, respectively. There was a significant improvement in motor praxis, vasomotor organization, thinking operations, and attention and concentration among older adults. In conclusion, moderate aerobic training for 24 weeks has a positive significant effect in improving cognitive functions via modulating redox and inflammatory status of older adults.

  7. In Situ Raman Study of Redox State Changes of Mitochondrial Cytochromes in a Perfused Rat Heart

    PubMed Central

    Brazhe, Nadezda A.; Treiman, Marek; Faricelli, Barbara; Vestergaard, Jakob H.; Sosnovtseva, Olga

    2013-01-01

    We developed a Raman spectroscopy-based approach for simultaneous study of redox changes in c-and b-type cytochromes and for a semiquantitative estimation of the amount of oxygenated myoglobin in a perfused rat heart. Excitation at 532 nm was used to obtain Raman scattering of the myocardial surface of the isolated heart at normal and hypoxic conditions. Raman spectra of the heart under normal pO2 demonstrate unique peaks attributable to reduced c-and b-type cytochromes and oxymyoglobin (oMb). The cytochrome peaks decreased in intensity upon FCCP treatment, as predicted from uncoupling mitochondrial respiration. Conversely, transient hypoxia causes the reversible increase in the intensity of peaks assigned to cytochromes c and c1, reflecting electron stacking proximal to cytochrome oxidase due to the lack of terminal electron acceptor O2. Intensities of peaks assigned to oxy- and deoxyhemoglobin were used for the semiquantitative estimation of oMb deoxygenation that was found to be of approximately 50 under hypoxia conditions. PMID:24009655

  8. In situ Raman study of redox state changes of mitochondrial cytochromes in a perfused rat heart.

    PubMed

    Brazhe, Nadezda A; Treiman, Marek; Faricelli, Barbara; Vestergaard, Jakob H; Sosnovtseva, Olga

    2013-01-01

    We developed a Raman spectroscopy-based approach for simultaneous study of redox changes in c-and b-type cytochromes and for a semiquantitative estimation of the amount of oxygenated myoglobin in a perfused rat heart. Excitation at 532 nm was used to obtain Raman scattering of the myocardial surface of the isolated heart at normal and hypoxic conditions. Raman spectra of the heart under normal pO2 demonstrate unique peaks attributable to reduced c-and b-type cytochromes and oxymyoglobin (oMb). The cytochrome peaks decreased in intensity upon FCCP treatment, as predicted from uncoupling mitochondrial respiration. Conversely, transient hypoxia causes the reversible increase in the intensity of peaks assigned to cytochromes c and c1, reflecting electron stacking proximal to cytochrome oxidase due to the lack of terminal electron acceptor O2. Intensities of peaks assigned to oxy- and deoxyhemoglobin were used for the semiquantitative estimation of oMb deoxygenation that was found to be of approximately 50[Formula: see text] under hypoxia conditions.

  9. Dexamethasone improves redox state in ataxia telangiectasia cells by promoting an NRF2-mediated antioxidant response.

    PubMed

    Biagiotti, Sara; Menotta, Michele; Orazi, Sara; Spapperi, Chiara; Brundu, Serena; Fraternale, Alessandra; Bianchi, Marzia; Rossi, Luigia; Chessa, Luciana; Magnani, Mauro

    2016-11-01

    Ataxia telangiectasia (A-T) is a rare incurable neurodegenerative disease caused by biallelic mutations in the gene for ataxia-telangiectasia mutated (ATM). The lack of a functional ATM kinase leads to a pleiotropic phenotype, and oxidative stress is considered to have a crucial role in the complex physiopathology. Recently, steroids have been shown to reduce the neurological symptoms of the disease, although the molecular mechanism of this effect is largely unknown. In the present study, we have demonstrated that dexamethasone treatment of A-T lymphoblastoid cells increases the content of two of the most abundant antioxidants [glutathione (GSH) and NADPH] by up to 30%. Dexamethasone promoted the nuclear accumulation of the transcription factor nuclear factor (erythroid-derived 2)-like 2 to drive expression of antioxidant pathways involved in GSH synthesis and NADPH production. The latter effect was via glucose 6-phosphate dehydrogenase activation, as confirmed by increased enzyme activity and enhancement of the pentose phosphate pathway rate. This evidence indicates that glucocorticoids are able to potentiate antioxidant defenses to counteract oxidative stress in ataxia telangiectasia, and also reveals an unexpected role for dexamethasone in redox homeostasis and cellular antioxidant activity. © 2016 The Authors. The FEBS Journal published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.

  10. Effects of Moderate Aerobic Exercise on Cognitive Abilities and Redox State Biomarkers in Older Adults

    PubMed Central

    Al-Eisa, Einas S.

    2016-01-01

    We used a moderate aerobic exercise program for 24 weeks to measure the positive impact of physical activity on oxidative stress and inflammatory markers and its association with cognitive performance in healthy older adults. A total of 100 healthy subjects (65–95 Yrs) were randomly classified into two groups: control group (n = 50) and exercise group (n = 50). Cognitive functioning, physical activity score, MDA, 8-OHdG, TAC, and hs-CRP were assessed using LOTCA battery, prevalidated PA questionnaire, and immunoassay techniques. LOTCA 7-set scores of cognitive performance showed a significant correlation with physical activity status and the regulation of both oxidative stress free radicals and inflammatory markers in all older subjects following 24 weeks of moderate exercise. Physically active persons showed a higher cognitive performance along with reduction in the levels of MDA, 8-OHdG, and hs-CRP and increase in TAC activity compared with sedentary participants. Cognitive performance correlated positively with the increase in TAC activity and physical fitness scores and negatively with MDA, 8-OHdG, and hs-CRP, respectively. There was a significant improvement in motor praxis, vasomotor organization, thinking operations, and attention and concentration among older adults. In conclusion, moderate aerobic training for 24 weeks has a positive significant effect in improving cognitive functions via modulating redox and inflammatory status of older adults. PMID:27195073

  11. Iron speciation and redox state of mantle eclogites: Implications for ancient volatile cycles during mantle melting and oceanic crust subduction

    NASA Astrophysics Data System (ADS)

    Aulbach, Sonja; Woodand, Alan; Vasilyev, Prokopiy; Viljoen, Fanus

    2017-04-01

    Kimberlite-borne mantle eclogite xenoliths of Archaean and Palaeoproterozoic age are commonly interpreted as representing former oceanic crust. As such, they may retain a memory of the redox state of the ancient convecting mantle sources that gave rise to their magmatic protoliths and which controls the speciation of volatiles in planetary interiors. Mantle eclogite suites commonly include both cumulate and variably evolved extrusive varieties [1], which may be characterised by initial differences in Fe3+/Fetotal. Recent Fe-based oxybarometry shows mantle eclogites to have fO2 relative to the fayalite-magnetite-quartz buffer (ΔFMQ) of -3 to 0, whereby low fO2 relative to modern MORB may relate to subduction of more reducing Archaean oceanic crust or loss of ferric Fe during partial melt loss [2]. Indeed, using V/Sc as a redox proxy, it was recently shown that Archaean mantle eclogites are more reduced than modern MORB (ΔFMQ-1.3 vs. ΔFMQ -0.4) [3]. However, in the warmer ancient mantle, they were also subject to modification due to partial melt loss upon recycling and, after capture in the cratonic mantle lithosphere, may be overprinted by interaction with metasomatic melts and fluids. In order to help further constrain the redox state of mantle eclogites and unravel the effect of primary and secondary processes, we measured Fe3+/Fetotal by Mössbauer in garnet from mantle eclogites from the Lace kimberlite (Kaapvaal craton), comprising samples with melt- and cumulate-like oceanic crustal protoliths as well as metasomatised samples. Fe3+/ΣFe in garnet shows a strong negative correlation with jadeite content and bulk-rock Li and Cu abundances, suggesting increased partitioning of Fe3+ into jadeite in the presence of monovalent cations with which it can form coupled substitutions. Broad negative correlation with whole-rock Al2O3/TiO2 and positive correlation with ΣREE are interpreted as incompatible behaviour of Fe3+ during olivine-plagioclase accumulation

  12. Adaptive estimation of state of charge and capacity with online identified battery model for vanadium redox flow battery

    NASA Astrophysics Data System (ADS)

    Wei, Zhongbao; Tseng, King Jet; Wai, Nyunt; Lim, Tuti Mariana; Skyllas-Kazacos, Maria

    2016-11-01

    Reliable state estimate depends largely on an accurate battery model. However, the parameters of battery model are time varying with operating condition variation and battery aging. The existing co-estimation methods address the model uncertainty by integrating the online model identification with state estimate and have shown improved accuracy. However, the cross interference may arise from the integrated framework to compromise numerical stability and accuracy. Thus this paper proposes the decoupling of model identification and state estimate to eliminate the possibility of cross interference. The model parameters are online adapted with the recursive least squares (RLS) method, based on which a novel joint estimator based on extended Kalman Filter (EKF) is formulated to estimate the state of charge (SOC) and capacity concurrently. The proposed joint estimator effectively compresses the filter order which leads to substantial improvement in the computational efficiency and numerical stability. Lab scale experiment on vanadium redox flow battery shows that the proposed method is highly authentic with good robustness to varying operating conditions and battery aging. The proposed method is further compared with some existing methods and shown to be superior in terms of accuracy, convergence speed, and computational cost.

  13. Enhanced hypothalamic glucose sensing in obesity: alteration of redox signaling.

    PubMed

    Colombani, Anne-Laure; Carneiro, Lionel; Benani, Alexandre; Galinier, Anne; Jaillard, Tristan; Duparc, Thibaut; Offer, Géraldine; Lorsignol, Anne; Magnan, Christophe; Casteilla, Louis; Pénicaud, Luc; Leloup, Corinne

    2009-10-01

    Recent data demonstrated that glucose sensing in different tissues is initiated by an intracellular redox signaling pathway in physiological conditions. However, the relevance of such a mechanism in metabolic disease is not known. The aim of the present study was to determine whether brain glucose hypersensitivity present in obese Zücker rats is related to an alteration in redox signaling. Brain glucose sensing alteration was investigated in vivo through the evaluation of electrical activity in arcuate nucleus, changes in reactive oxygen species levels, and hypothalamic glucose-induced insulin secretion. In basal conditions, modifications of redox state and mitochondrial functions were assessed through oxidized glutathione, glutathione peroxidase, manganese superoxide dismutase, aconitase activities, and mitochondrial respiration. Hypothalamic hypersensitivity to glucose was characterized by enhanced electrical activity of the arcuate nucleus and increased insulin secretion at a low glucose concentration, which does not produce such an effect in normal rats. It was associated with 1) increased reactive oxygen species levels in response to this low glucose load, 2) constitutive oxidized environment coupled with lower antioxidant enzyme activity at both the cellular and mitochondrial level, and 3) overexpression of several mitochondrial subunits of the respiratory chain coupled with a global dysfunction in mitochondrial activity. Moreover, pharmacological restoration of the glutathione hypothalamic redox state by reduced glutathione infusion in the third ventricle fully reversed the cerebral hypersensitivity to glucose. The data demonstrated that obese Zücker rats' impaired hypothalamic regulation in terms of glucose sensing is linked to an abnormal redox signaling, which originates from mitochondria dysfunction.

  14. Direct determination of the redox status of cysteine residues in proteins in vivo

    SciTech Connect

    Hara, Satoshi; Tatenaka, Yuki; Ohuchi, Yuya; Hisabori, Toru

    2015-01-02

    Highlights: • A new DNA-maleimide which is cleaved by UV irradiation, DNA-PCMal, was developed. • DNA-PCMal can be used like DNA-Mal to analyze the redox state of cysteine residues. • It is useful for detecting the thiol redox status of a protein in vivo by Western blotting method. • Thus, DNA-PCMal can be a powerful tool for redox proteomics analysis. - Abstract: The redox states of proteins in cells are key factors in many cellular processes. To determine the redox status of cysteinyl thiol groups in proteins in vivo, we developed a new maleimide reagent, a photocleavable maleimide-conjugated single stranded DNA (DNA-PCMal). The DNA moiety of DNA-PCMal is easily removed by UV-irradiation, allowing DNA-PCMal to be used in Western blotting applications. Thereby the state of thiol groups in intracellular proteins can be directly evaluated. This new maleimide compound can provide information concerning redox proteins in vivo, which is important for our understanding of redox networks in the cell.

  15. Redox regulation of morphology, cell stiffness, and lectin-induced aggregation of human platelets.

    PubMed

    Shamova, Ekaterina V; Gorudko, Irina V; Drozd, Elizaveta S; Chizhik, Sergey A; Martinovich, Grigory G; Cherenkevich, Sergey N; Timoshenko, Alexander V

    2011-02-01

    Redox regulation and carbohydrate recognition are potent molecular mechanisms which can contribute to platelet aggregation in response to various stimuli. The purpose of this study is to investigate the relationship between these mechanisms and to examine whether cell surface glycocalyx and cell stiffness of human platelets are sensitive to the redox potential formed by glutathione. To this end, human platelets were treated with different concentrations (0.05 μM to 6 mM) and ratios of reduced or oxidized glutathione (GSH or GSSG), and platelet morphological, mechanical, and functional properties were determined using conventional light microscopy, atomic force microscopy, and lectin-induced cell aggregation analysis. It was found that lowering the glutathione redox potential changed platelet morphology and increased platelet stiffness as well as modulated nonuniformly platelet aggregation in response to plant lectins with different carbohydrate-binding specificity including wheat germ agglutinin, Sambucus nigra agglutinin, and Canavalia ensiformis agglutinin. Extracellular redox potential and redox buffering capacity of the GSSG/2GSH couple were shown to control the availability of specific lectin-binding glycoligands on the cell surface, while the intracellular glutathione redox state affected the general functional ability of platelets to be aggregated independently of the type of lectins. Our data provide the first experimental evidence that glutathione as a redox molecule can affect the mechanical stiffness of human platelets and induce changes of the cell surface glycocalyx, which may represent a new mechanism of redox regulation of intercellular contacts.

  16. Changes in redox states of respiratory pigments recorded from the eyes of live blowflies exposed to light stimuli and hypoxia.

    PubMed

    Meglič, Andrej; Zupančič, Gregor

    2011-03-01

    Time courses of mitochondrial responses to illumination-induced physiological loads and to hypoxia, were recorded optically from eyes of blowflies Calliphora vicina chalky. We isolated changes in redox states of haems a(3), a, c, and b. Two types of responses to light stimulation were observed. Haems b and a(3) responded with transient oxidation and haems a and c with reduction. The same two groups emerged in response to anoxic exposure. The onset of reduction of haems a and c had virtually no latency, while haems a(3) and b exhibited a transient oxidation followed by reduction only after 10-20 s. The dependence of the steady-state reduction level on [Formula: see text] produced the same groups. Haems a and c were significantly reduced at [Formula: see text] levels around 10 kPa while with haems b and a(3) load-induced oxidation was only replaced by reduction below 2 kPa. We propose haems respond to physiological loads in accordance with their steady-state reduction, which in turn depends largely on barriers for electron transport imposed by the mitochondrial membrane potential. We also propose it may be possible to assess the values of tissue [Formula: see text] and O(2) consumption by monitoring haems that are highly oxidized at rest such as haem a.

  17. Redox State of Pentraxin 3 as a Novel Biomarker for Resolution of Inflammation and Survival in Sepsis*

    PubMed Central

    Cuello, Friederike; Shankar-Hari, Manu; Mayr, Ursula; Yin, Xiaoke; Marshall, Melanie; Suna, Gonca; Willeit, Peter; Langley, Sarah R.; Jayawardhana, Tamani; Zeller, Tanja; Terblanche, Marius; Shah, Ajay M.; Mayr, Manuel

    2014-01-01

    In an endotoxaemic mouse model of sepsis, a tissue-based proteomics approach for biomarker discovery identified long pentraxin 3 (PTX3) as the lead candidate for inflamed myocardium. When the redox-sensitive oligomerization state of PTX3 was further investigated, PTX3 accumulated as an octamer as a result of disulfide-bond formation in heart, kidney, and lung—common organ dysfunctions seen in patients with sepsis. Oligomeric moieties of PTX3 were also detectable in circulation. The oligomerization state of PTX3 was quantified over the first 11 days in critically ill adult patients with sepsis. On admission day, there was no difference in the oligomerization state of PTX3 between survivors and non-survivors. From day 2 onward, the conversion of octameric to monomeric PTX3 was consistently associated with a greater survival after 28 days of follow-up. For example, by day 2 post-admission, octameric PTX3 was barely detectable in survivors, but it still constituted more than half of the total PTX3 in non-survivors (p < 0.001). Monomeric PTX3 was inversely associated with cardiac damage markers NT-proBNP and high-sensitivity troponin I and T. Relative to the conventional measurements of total PTX3 or NT-proBNP, the oligomerization of PTX3 was a superior predictor of disease outcome. PMID:24958171

  18. Redox state of pentraxin 3 as a novel biomarker for resolution of inflammation and survival in sepsis.

    PubMed

    Cuello, Friederike; Shankar-Hari, Manu; Mayr, Ursula; Yin, Xiaoke; Marshall, Melanie; Suna, Gonca; Willeit, Peter; Langley, Sarah R; Jayawardhana, Tamani; Zeller, Tanja; Terblanche, Marius; Shah, Ajay M; Mayr, Manuel

    2014-10-01

    In an endotoxaemic mouse model of sepsis, a tissue-based proteomics approach for biomarker discovery identified long pentraxin 3 (PTX3) as the lead candidate for inflamed myocardium. When the redox-sensitive oligomerization state of PTX3 was further investigated, PTX3 accumulated as an octamer as a result of disulfide-bond formation in heart, kidney, and lung-common organ dysfunctions seen in patients with sepsis. Oligomeric moieties of PTX3 were also detectable in circulation. The oligomerization state of PTX3 was quantified over the first 11 days in critically ill adult patients with sepsis. On admission day, there was no difference in the oligomerization state of PTX3 between survivors and non-survivors. From day 2 onward, the conversion of octameric to monomeric PTX3 was consistently associated with a greater survival after 28 days of follow-up. For example, by day 2 post-admission, octameric PTX3 was barely detectable in survivors, but it still constituted more than half of the total PTX3 in non-survivors (p < 0.001). Monomeric PTX3 was inversely associated with cardiac damage markers NT-proBNP and high-sensitivity troponin I and T. Relative to the conventional measurements of total PTX3 or NT-proBNP, the oligomerization of PTX3 was a superior predictor of disease outcome. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  19. Experimental and theoretical approaches to redox innocence of ligands in uranyl complexes: what is formal oxidation state of uranium in reductant of uranyl(VI)?

    PubMed

    Takao, Koichiro; Tsushima, Satoru; Ogura, Toshinari; Tsubomura, Taro; Ikeda, Yasuhisa

    2014-06-02

    Redox behavior of [UO2(gha)DMSO](-)/UO2(gha)DMSO couple (gha = glyoxal bis(2-hydroxanil)ate, DMSO = dimethyl sulfoxide) in DMSO solution was investigated by cyclic voltammetry and UV-vis-NIR spectroelectrochemical technique, as well as density functional theory (DFT) calculations. [UO2(gha)DMSO](-) was found to be formed via one-electron reduction of UO2(gha)DMSO without any successive reactions. The observed absorption spectrum of [UO2(gha)DMSO](-), however, has clearly different characteristics from those of uranyl(V) complexes reported so far. Detailed analysis of molecular orbitals and spin density of the redox couple showed that the gha(2-) ligand in UO2(gha)DMSO is reduced to gha(•3-) to give [UO2(gha)DMSO](-) and the formal oxidation state of U remains unchanged from +6. In contrast, the additional DFT calculations confirmed that the redox reaction certainly occurs at the U center in other uranyl(V/VI) redox couples we found previously. The noninnocence of the Schiff base ligand in the [UO2(gha)DMSO](-)/UO2(gha)DMSO redox couple is due to the lower energy level of LUMO in this ligand relative to those of U 5f orbitals. This is the first example of the noninnocent ligand system in the coordination chemistry of uranyl(VI).

  20. The impact of aging, hearing loss, and body weight on mouse hippocampal redox state, measured in brain slices using fluorescence imaging.

    PubMed

    Stebbings, Kevin A; Choi, Hyun W; Ravindra, Aditya; Llano, Daniel Adolfo

    2016-06-01

    The relationships between oxidative stress in the hippocampus and other aging-related changes such as hearing loss, cortical thinning, or changes in body weight are not yet known. We measured the redox ratio in a number of neural structures in brain slices taken from young and aged mice. Hearing thresholds, body weight, and cortical thickness were also measured. We found striking aging-related increases in the redox ratio that were isolated to the stratum pyramidale, while such changes were not observed in thalamus or cortex. These changes were driven primarily by changes in flavin adenine dinucleotide, not nicotinamide adenine dinucleotide hydride. Multiple regression analysis suggested that neither hearing threshold nor cortical thickness independently contributed to this change in hippocampal redox ratio. However, body weight did independently contribute to predicted changes in hippocampal redox ratio. These data suggest that aging-related changes in hippocampal redox ratio are not a general reflection of overall brain oxidative state but are highly localized, while still being related to at least one marker of late aging, weight loss at the end of life. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. [The role of oxidative protein modification and the gluthatione system in modulation of the redox status of breast epithelial cells].

    PubMed

    Stepovaya, E A; Shakhristova, E V; Ryazantseva, N V; Nosareva, O L; Yakushina, V D; Nosova, A I; Gulaya, V S; Stepanova, E A; Chil'chigashev, R I; Novitsky, V V

    2016-01-01

    The effects of the SH-group blocker N-ethylmaleimide (NEM) and thiol group protector 1,4-dithioerythritol (DTE) on the redox status of cells HBL-100 cells, oxidative modification of their proteins and the state of glutathione and thioredoxin systems have been investigated. Breast epithelial cells cultivated in the presence of NEM were characterized by decreased redox status, increased glutathione reductase activity, and increased concentrations of products of irreversible oxidative modification of protein and amino acids. Cultivation of HBL-100 cells in the presence of DTE resulted in a shift of the redox status towards reduction processes and increased reversible protein modification by glutathionylation. The proposed model of intracellular redox modulation may be used in the development of new therapeutic approaches to treat diseases accompanied by impaired redox homeostasis (e.g. oncologic, inflammatory, cardiovascular and neurodegenerative disease).

  2. Myocardial redox state predicts in-hospital clinical outcome after cardiac surgery effects of short-term pre-operative statin treatment.

    PubMed

    Antoniades, Charalambos; Demosthenous, Michael; Reilly, Svetlana; Margaritis, Marios; Zhang, Mei-Hua; Antonopoulos, Alexios; Marinou, Kyriakoula; Nahar, Keshav; Jayaram, Raja; Tousoulis, Dimitris; Bakogiannis, Constantinos; Sayeed, Rana; Triantafyllou, Costas; Koumallos, Nikolaos; Psarros, Costas; Miliou, Antigoni; Stefanadis, Christodoulos; Channon, Keith M; Casadei, Barbara

    2012-01-03

    The purpose of this study was to evaluate the role of the myocardial redox state in the development of in-hospital complications after cardiac surgery and the effect of statins on the myocardial redox state. Statins improve clinical outcome after cardiac surgery, but it is unclear whether they exert their effects by modifying the myocardial redox state. We quantified myocardial superoxide anion (O(2)(-)) and peroxynitrite (ONOO(-)) and their enzymatic sources in samples of the right atrial appendage (RAA) from 303 patients undergoing cardiac surgery who were followed up until discharge, and in 42 patients who were randomized to receive 3-day treatment with atorvastatin 40 mg/d or placebo before surgery. The mechanisms by which atorvastatin modifies myocardial redox state were investigated in 26 RAA samples that were exposed to atorvastatin ex vivo. Atrial O(2)(-) (derived mainly from nicotinamide adenine dinucleotide phosphate [NADPH] oxidases) and ONOO(-) were independently associated with increased risk of atrial fibrillation, the need for post-operative inotropic support, and the length of hospital stay. Pre-operative atorvastatin treatment suppressed atrial NADPH oxidase activity and myocardial O(2)(-) and ONOO(-) production. Ex vivo incubation of RAA samples with atorvastatin induced a mevalonate-reversible and Rac1-mediated inhibition of NADPH oxidase. There is a strong independent association between myocardial O(2)(-)/ONOO(-) and in-hospital complications after cardiac surgery. Both myocardial O(2)(-) and ONOO(-) are reduced by pre-operative statin treatment, through a Rac1-mediated suppression of NADPH oxidase activity. These findings suggest that inhibition of myocardial NADPH oxidases may contribute to the beneficial effect of statins in patients undergoing cardiac surgery. (Effects of Atorvastatin on Endothelial Function, Vascular and Myocardial Redox State in High Cardiovascular Risk Patients; NCT01013103). Copyright © 2012 American College of

  3. A redox-responsive transcription factor is critical for pathogenesis and aerobic growth of Listeria monocytogenes.

    PubMed

    Whiteley, Aaron T; Ruhland, Brittany R; Edrozo, Mauna B; Reniere, Michelle L

    2017-02-13

    Bacterial pathogens have evolved sophisticated mechanisms to sense and adapt to redox stress in nature and within the host. However, deciphering the redox environment encountered by intracellular pathogens in the mammalian cytosol is challenging and remains poorly understood. In this study, we assessed the contributions of the two redox-responsive, Spx-family transcriptional regulators to the virulence of Listeria monocytogenes, a Gram-positive facultative intracellular pathogen. Spx-family proteins are highly conserved in Firmicutes and L. monocytogenes encodes two paralogues, spxA1 and spxA2 Here, we demonstrated that spxA1, but not spxA2, was required for the oxidative stress response and pathogenesis. SpxA1 function appeared to be conserved with the Bacillus subtilis homologue and resistance to oxidative stress required the canonical CXXC redox-sensing motif. Remarkably, spxA1 was essential for aerobic growth, demonstrating that L. monocytogenes SpxA1 likely regulates a distinct set of genes. Although the ΔspxA1 mutant did not grow in the presence of oxygen in the laboratory, it was able to replicate in macrophages and colonize the spleens, but not the livers, of infected mice. These data suggest that the redox state of bacteria during infection differs significantly from bacteria growing in vitro Further, the host cell cytosol may resemble an anaerobic environment with tissue-specific variations in redox stress and oxygen concentration.

  4. Intracellular lipid content is a key intrinsic determinant for hepatocyte viability and metabolic and inflammatory states in mice

    PubMed Central

    Sheng, Liang; Jiang, Bijie

    2013-01-01

    The liver is an essential metabolic organ. In addition to metabolizing glucose and lipids, hepatocytes also secrete various cytokines that modulate both hepatocyte metabolism and liver inflammation. Hepatocyte injury and death and liver inflammation are the major contributors to liver diseases, including nonalcoholic steatohepatitis (NASH). Anatomic locations have a profound effect on hepatocyte metabolism, and liver zonation describes the metabolic heterogeneity of hepatocytes along the portovenous axis. However, it is unclear whether hepatocyte heterogeneity is affected by intrinsic factors and whether dietary fat, a risk factor for NASH, has distinct detrimental effects on different hepatocyte subpopulations. Here, we showed that mouse livers contained both high-lipid and low-lipid subpopulations of hepatocytes. The high-lipid subpopulation was more susceptible to injury and apoptosis and produced more proinflamatrory cytokines after treatment with endotoxin and saturated fatty acids. Dietary fat consumption further increased fatty acid uptake, intracellular lipid levels, hepatocyte injury and death, and the expression of proinflammatory cytokines in the high-lipid subpopulation. In contrast, dietary fat slightly increased lipid levels, cell death, and expression of proinflammatory cytokines in the low-lipid subpopulation. The low-lipid subpopulation produced more glucose. Fat consumption further activated the gluconeogenic program in the low-lipid, but not the high-lipid, subpopulations. These data suggest that intracellular lipid content is a key intrinsic determinant for hepatocyte heterogeneity of metabolic, inflammatory, and survival states. PMID:23982157

  5. Inadequacy of high K+/nigericin for calibrating BCECF. I. Estimating steady-state intracellular pH.

    PubMed

    Boyarsky, G; Hanssen, C; Clyne, L A

    1996-10-01

    Intracellular pH (pHi) was measured in single vascular smooth muscle (VSM) cells, cultured from rabbit abdominal aorta, using 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein (BCECF) on a microscope-based fluorescence system. Three lines of evidence are presented that using nigericin along with high external K+ to calibrate intracellular BCECF produces systematic errors in pHi. 1) The intrinsic buffering power (beta int), measured using weak bases (e.g., ammonium), was 2.5 times smaller than that measured using weak acids (e.g., propionic acid). This discrepancy became small if pHi had really been approximately 0.2 lower than what was estimated using nigericin-calibrated pHi values. 2) Total cellular buffering power (beta tot) in the presence of CO2/HCO-3 was measured and found to be much smaller than could account for the beta int, together with the contribution of CO2/HCO3 (beta CO2: assumed to be an open system buffer). If the true pHi values were approximately 0.2-0.4 lower than our nigericin-calibrated values, then the sum of beta int and beta CO2 equals beta tot. 3) A null technique was utilized for bracketing steady-state pHi; estimates of steady-state pHi using this null technique were approximately 0.2 lower than the high K+/nigericin-calibrated estimates. Four other cell types were examined: rat hepatocytes, rat corticotrophs, human keratinocytes, and rabbit fibroblasts. These other cells also displayed discrepancies between null and nigericin estimates of steady-state pHi, as well as differences between buffering power assessed using weak bases and acids. Finally, one potential source for these discrepancies is described: selecting an inappropriate external K+ to use with nigericin can produce systematic errors in pHi of approximately 0.1.

  6. Copy number variations of genes involved in stress responses reflect the redox state and DNA damage in brewing yeasts.

    PubMed

    Adamczyk, Jagoda; Deregowska, Anna; Skoneczny, Marek; Skoneczna, Adrianna; Natkanska, Urszula; Kwiatkowska, Aleksandra; Rawska, Ewa; Potocki, Leszek; Kuna, Ewelina; Panek, Anita; Lewinska, Anna; Wnuk, Maciej

    2016-09-01

    The yeast strains of the Saccharomyces sensu stricto complex involved in beer production are a heterogeneous group whose genetic and genomic features are not adequately determined. Thus, the aim of the present study was to provide a genetic characterization of selected group of commercially available brewing yeasts both ale top-fermenting and lager bottom-fermenting strains. Molecular karyotyping revealed that the diversity of chromosome patterns and four strains with the most accented genetic variabilities were selected and subjected to genome-wide array-based comparative genomic hybridization (array-CGH) analysis. The differences in the gene copy number were found in five functional gene categories: (1) maltose metabolism and transport, (2) response to toxin, (3) siderophore transport, (4) cellular aldehyde metabolic process, and (5) L-iditol 2-dehydrogenase activity (p < 0.05). In the Saflager W-34/70 strain (Fermentis) with the most affected array-CGH profile, loss of aryl-alcohol dehydrogenase (AAD) gene dosage correlated with an imbalanced redox state, oxidative DNA damage and breaks, lower levels of nucleolar proteins Nop1 and Fob1, and diminished tolerance to fermentation-associated stress stimuli compared to other strains. We suggest that compromised stress response may not only promote oxidant-based changes in the nucleolus state that may affect fermentation performance but also provide novel directions for future strain improvement.

  7. Mouse redox histology using genetically encoded probes.

    PubMed

    Fujikawa, Yuuta; Roma, Leticia P; Sobotta, Mirko C; Rose, Adam J; Diaz, Mauricio Berriel; Locatelli, Giuseppe; Breckwoldt, Michael O; Misgeld, Thomas; Kerschensteiner, Martin; Herzig, Stephan; Müller-Decker, Karin; Dick, Tobias P

    2016-03-15

    Mapping the in vivo distribution of endogenous oxidants in animal tissues is of substantial biomedical interest. Numerous health-related factors, including diet, physical activity, infection, aging, toxins, or pharmacological intervention, may cause redox changes. Tools are needed to pinpoint redox state changes to particular organs, tissues, cell types, and subcellular organelles. We describe a procedure that preserves the in vivo redox state of genetically encoded redox biosensors within histological tissue sections, thus providing "redox maps" for any tissue and comparison of interest. We demonstrate the utility of the technique by visualizing endogenous redox differences and changes in the context of tumor growth, inflammation, embryonic development, and nutrient starvation.

  8. Fe and S redox states during serpentinite dehydration in subduction settings

    NASA Astrophysics Data System (ADS)

    Merkulova, Margarita; Munoz, Manuel; Vidal, Olivier; Brunet, Fabrice

    2016-04-01

    present highly oxidizing properties. At higher P-T conditions, higher amounts of water are released with minor oxygen release. In addition, sulfur is shown to be progressively reduced at temperature 450-500°C due to pyrite to pyrrhotite transition. The reaction of pyrite reduction was observed to happen with sequestration of Fe from silicates and a release of oxygen. Effectively, the presence of sulphides in serpentinites contribute additional oxygen to the fluid, whereas the release of S may be negligible. The detailed study of the evolution of redox conditions during serpentinite dehydration in subduction zones will help constraining, 1) the behavior and mobility, from slab to the upper mantle, of elements of economical interest, as well as 2) the global geochemical cycling of elements. References: 1. Hacker et al. (2003) J. Geophys. Res. 108, article number 2029. 2. Ulmer & Trommsdorff (1995) Science 268, 858-861. 3. Debret et al. (2014) EPSL 400, 206-218. 4. Alt et al. (2013) Lithos 178, 40-54. 5. Pokrovski & Dubrovinsky (2011) Science 331, 1052-1056.

  9. Both the concentration and redox state of glutathione and ascorbate influence the sensitivity of arabidopsis to cadmium

    PubMed Central

    Jozefczak, Marijke; Bohler, Sacha; Schat, Henk; Horemans, Nele; Guisez, Yves; Remans, Tony; Vangronsveld, Jaco; Cuypers, Ann

    2015-01-01

    Background and Aims Cadmium (Cd) is a non-essential trace element that elicits oxidative stress. Plants respond to Cd toxicity via increasing their Cd-chelating and antioxidative capacities. They predominantly chelate Cd via glutathione (GSH) and phytochelatins (PCs), while antioxidative defence is mainly based on the use and recycling of both GSH and ascorbate (AsA), complemented by superoxide dismutase (SOD) and catalase (CAT). In addition, both metabolites act as a substrate for the regeneration of other essential antioxidants, which neutralize and regulate reactive oxygen species (ROS). Together, these functions influence the concentration and cellular redox state of GSH and AsA. In this study, these two parameters were examined in plants of Arabidopsis thaliana exposed to sub-lethal Cd concentrations. Methods Wild-type plants and mutant arabidopsis plants containing 30–45 % of wild-type levels of GSH (cad2-1) or 40–50 % of AsA (vtc1-1), together with the double-mutant (cad2-1 vtc1-1) were cultivated in a hydroponic system and exposed to sub-lethal Cd concentrations. Cadmium detoxification was investigated at different levels including gene expression and metabolite concentrations. Key Results In comparison with wild-type plants, elevated basal thiol levels and enhanced PC synthesis upon exposure to Cd efficiently compensated AsA deficiency in vtc1-1 plants and contributed to decreased sensitivity towards Cd. Glutathione-deficient (cad2-1 and cad2-1 vtc1-1) mutants, however, showed a more oxidized GSH redox state, resulting in initial oxidative stress and a higher sensitivity to Cd. In order to cope with the Cd stress to which they were exposed, GSH-deficient mutants activated multiple alternative pathways. Conclusions Our observations indicate that GSH and AsA deficiency differentially alter plant GSH homeostasis, resulting in opposite Cd sensitivities relative to wild-type plants. Upon Cd exposure, GSH-deficient mutants were hampered in chelation. They

  10. Organ specific mapping of in vivo redox state in control and cigarette smoke-exposed mice using EPR/NMR co-imaging

    PubMed Central

    Caia, George L.; Efimova, Olga V.; Velayutham, Murugesan; El-Mahdy, Mohamed A.; Abdelghany, Tamer M.; Kesselring, Eric; Petryakov, Sergey; Sun, Ziqi; Samouilov, Alexandre; Zweier, Jay L.

    2014-01-01

    In vivo mapping of alterations in redox status is important for understanding organ specific pathology and disease. While electron paramagnetic resonance imaging (EPRI) enables spatial mapping of free radicals, it does not provide anatomic visualization of the body. Proton MRI is well suited to provide anatomical visualization. We applied EPR/NMR co-imaging instrumentation to map and monitor the redox state of living mice under normal or oxidative stress conditions induced by secondhand cigarette smoke (SHS) exposure. A hybrid co-imaging instrument, EPRI (1.2 GHz) / proton MRI (16.18 MHz), suitable for whole-body co-imaging of mice was utilized with common magnet and gradients along with dual EPR/NMR resonators that enable co-imaging without sample movement. The metabolism of the nitroxide probe, 3–carbamoyl–proxyl (3-CP), was used to map the redox state of control and SHS-exposed mice. Co-imaging allowed precise 3D mapping of radical distribution and reduction in major organs such as the heart, lungs, liver, bladder and kidneys. Reductive metabolism was markedly decreased in SHS-exposed mice and EPR/NMR co-imaging allowed quantitative assessment of this throughout the body. Thus, in vivo EPR/NMR co-imaging enables in vivo organ specific mapping of free radical metabolism and redox stress and the alterations that occur in the pathogenesis of disease. PMID:22296801

  11. Organ specific mapping of in vivo redox state in control and cigarette smoke-exposed mice using EPR/NMR co-imaging

    NASA Astrophysics Data System (ADS)

    Caia, George L.; Efimova, Olga V.; Velayutham, Murugesan; El-Mahdy, Mohamed A.; Abdelghany, Tamer M.; Kesselring, Eric; Petryakov, Sergey; Sun, Ziqi; Samouilov, Alexandre; Zweier, Jay L.

    2012-03-01

    In vivo mapping of alterations in redox status is important for understanding organ specific pathology and disease. While electron paramagnetic resonance imaging (EPRI) enables spatial mapping of free radicals, it does not provide anatomic visualization of the body. Proton MRI is well suited to provide anatomical visualization. We applied EPR/NMR co-imaging instrumentation to map and monitor the redox state of living mice under normal or oxidative stress conditions induced by secondhand cigarette smoke (SHS) exposure. A hybrid co-imaging instrument, EPRI (1.2 GHz)/proton MRI (16.18 MHz), suitable for whole-body co-imaging of mice was utilized with common magnet and gradients along with dual EPR/NMR resonators that enable co-imaging without sample movement. The metabolism of the nitroxide probe, 3-carbamoyl-proxyl (3-CP), was used to map the redox state of control and SHS-exposed mice. Co-imaging allowed precise 3D mapping of radical distribution and reduction in major organs such as the heart, lungs, liver, bladder and kidneys. Reductive metabolism was markedly decreased in SHS-exposed mice and EPR/NMR co-imaging allowed quantitative assessment of this throughout the body. Thus, in vivo EPR/NMR co-imaging enables in vivo organ specific mapping of free radical metabolism and redox stress and the alterations that occur in the pathogenesis of disease.

  12. Excited State Processes in Transition Metal Complexes, Redox Splitting in Soluble Polymers

    SciTech Connect

    Meyer, T.J.; Papanikolas, J.M.

    2002-08-08

    The photochemical and photophysical properties of polypyridyl complexes of Ru, Os, and Re have been investigated by transient absorption, emission, resonance raman and infrared spectroscopies. The latter technique has been especially useful in defining the acceptor ligand in metal-to-ligand charge transfer (MLCT) excited states and probing the details of excited state electronic and molecular structure. Derivatives of these complexes have been attached to soluble polystyrene polymers. In the resulting metal complex polymer composites it has been possible to demonstrate long range energy transfer and the existence of an antenna effect and create a mimic for the active site in the photosynthetic membrane.

  13. Is regulation of proteolysis associated with redox-state changes in rat skeletal muscle?

    PubMed Central

    Tischler, M E

    1980-01-01

    In isolated rat diaphragms, only those substrates that increased the tissue NADH/NAD+ ratio lowered the rate of proteolysis. However, direct inhibition of proteinase activity by leupeptin promoted oxidation of the NAD couple of the muscles. These results suggest that changes in muscle reduction-oxidation state may be important in the regulation of proteolysis. PMID:7236250

  14. Energy conversion based on molecular excited states: Redox splitting in soluble polymers. Final report

    SciTech Connect

    Meyer, T.J.

    1995-12-31

    A general method was developed for preparing complexes of Ru(II) with three different bidentate ligands; it is being extended to monodentate ligands for more synthetic versatility. This method was used to prepare a series of complexes with pre-designed absorption properties, with the goal of ``black absorbers`` for use as antenna chromophores in a light-to-chemical energy conversion array. The energy gap law for nonradiative decay was studied for preparing near-IR luminophores with long excited state lifetimes. The problem of destructive dd excited states in Ru(II) polypyridyl complexes was focused on, with success in preparing an extremely photo-inert complex with monodentate pyridine ligands. Time-resolved resonance Raman and infrared spectroscopy were used to study subtle excited state properties of complexes of Ru(II), Os(II), and Re(I). Success was achieved in controlled immobilization of d{sup 6} chromophores and quenchers on styrenic polymers. Having perfected our synthetic technique, we have begun to optimize the ground and excited state properties such as chromophore density, dipole orientation, and lifetime.

  15. Comment on "Iron isotope constraints on the Archean and Paleoproterozoic ocean redox state".

    PubMed

    Yamaguchi, Kosei E; Ohmoto, Hiroshi

    2006-01-13

    Rouxel et al. (Reports, 18 February 2005, p. 1088) argued that changes in the iron isotopic composition of sedimentary sulfides reflect changes in the oxidation state of the atmosphere-ocean system between 2.3 and 1.8 million years ago. We show that misinterpretations of the origins of these minerals undermine their conclusions.

  16. Globin-based redox signaling

    PubMed Central

    De Henau, Sasha; Braeckman, Bart P.

    2016-01-01

    ABSTRACT In recent years, moderate levels of reactive oxygen species (ROS) have become recognized as signaling cues that participate at all levels of cellular organization. Globins, with their redox-active heme iron and ubiquitous presence, seem ideally suited to participate in ROS metabolism. Here we comment on our recent findings that show the participation of a globin, GLB-12, in a redox signaling pathway in Caenorhabditis elegans. We found that GLB-12 produces superoxide, a type of ROS, after which this is converted to what appears to be a hydrogen peroxide gradient over the plasma membrane by the activity of intracellular and extracellular superoxide dismutases. In the first part, we discuss in more detail the different regulatory mechanisms that increase the effectiveness of this redox signal. In the second part, we comment on how specific structural and biochemical properties allow this globin to perform redox reactions. Interestingly, these properties are also observed in 2 other C. elegans globins that appear to be involved in redox biology. We therefore hypothesize that globins involved in redox signaling display similar structural and biochemical characteristics and propose that a subgroup of globins can be added to the group of proteins that play a vital role in redox signaling. PMID:27695650

  17. Globin-based redox signaling.

    PubMed

    De Henau, Sasha; Braeckman, Bart P

    2016-01-01

    In recent years, moderate levels of reactive oxygen species (ROS) have become recognized as signaling cues that participate at all levels of cellular organization. Globins, with their redox-active heme iron and ubiquitous presence, seem ideally suited to participate in ROS metabolism. Here we comment on our recent findings that show the participation of a globin, GLB-12, in a redox signaling pathway in Caenorhabditis elegans. We found that GLB-12 produces superoxide, a type of ROS, after which this is converted to what appears to be a hydrogen peroxide gradient over the plasma membrane by the activity of intracellular and extracellular superoxide dismutases. In the first part, we discuss in more detail the different regulatory mechanisms that increase the effectiveness of this redox signal. In the second part, we comment on how specific structural and biochemical properties allow this globin to perform redox reactions. Interestingly, these properties are also observed in 2 other C. elegans globins that appear to be involved in redox biology. We therefore hypothesize that globins involved in redox signaling display similar structural and biochemical characteristics and propose that a subgroup of globins can be added to the group of proteins that play a vital role in redox signaling.

  18. Intracellular energy status regulates activity in hypocretin/orexin neurones: a link between energy and behavioural states

    PubMed Central

    Liu, Zhong-Wu; Gan, Geliang; Suyama, Shigetomo; Gao, Xiao-Bing

    2011-01-01

    Abstract The hypocretin/orexin (Hcrt)-containing neurones within the lateral hypothalamus integrate nutritional, energetic and behavioural cues to generate the final output in order to exert their functions. It is still not clear how Hcrt neurones monitor changes in energy status in animals. In brain slices from transgenic mice expressing green fluorescent protein (GFP) exclusively in Hcrt neurones, we examined the roles of intracellular levels of ATP ([ATP]i) in regulating activities in these cells with conventional and perforated whole-cell recording. By using ‘ATP clamp’ we demonstrated that membrane potential (Vm) correlated with the [ATP]i in Hcrt neurones. Perforated recording revealed a Vm of −46.1 ± 1.6 mV (n = 18), close to the level measured with an [ATP]i equal to 5–6 mm (–48.7 ± 1.4 mV, n = 16, 5 mm ATP), suggesting that a unique demand for energy is required to maintain normal functionality in Hcrt cells. A direct disruption of ATP production or reduction in ambient glucose levels resulted in an inhibition of activity in Hcrt neurones. The Vm was significantly depolarized in Hcrt neurones in sleep-deprived mice as compared with controls (P < 0.01, t test), which was eliminated by experimental manipulations causing the same level of [ATP]i and KATP channel opening in both groups, suggesting a decrease during sleep and an increase during sustained wakefulness in [ATP]i in Hcrt cells. In summary, these data demonstrate that a delicate control of activity by monitoring the availability of intracellular energy stores in Hcrt cells may serve as a novel mechanism regulating energy expenditure and behavioural state dependent upon the energy state in animals. PMID:21727218

  19. Intracellular energy status regulates activity in hypocretin/orexin neurones: a link between energy and behavioural states.

    PubMed

    Liu, Zhong-Wu; Gan, Geliang; Suyama, Shigetomo; Gao, Xiao-Bing

    2011-09-01

    The hypocretin/orexin (Hcrt)-containing neurones within the lateral hypothalamus integrate nutritional, energetic and behavioural cues to generate the final output in order to exert their functions. It is still not clear how Hcrt neurones monitor changes in energy status in animals. In brain slices from transgenic mice expressing green fluorescent protein (GFP) exclusively in Hcrt neurones, we examined the roles of intracellular levels of ATP ([ATP](i)) in regulating activities in these cells with conventional and perforated whole-cell recording. By using 'ATP clamp' we demonstrated that membrane potential (V(m)) correlated with the [ATP](i) in Hcrt neurones. Perforated recording revealed a V(m) of -46.1 ± 1.6 mV (n = 18), close to the level measured with an [ATP](i) equal to 5-6 mm (-48.7 ± 1.4 mV, n = 16, 5 mm ATP), suggesting that a unique demand for energy is required to maintain normal functionality in Hcrt cells. A direct disruption of ATP production or reduction in ambient glucose levels resulted in an inhibition of activity in Hcrt neurones. The V(m) was significantly depolarized in Hcrt neurones in sleep-deprived mice as compared with controls (P < 0.01, t test), which was eliminated by experimental manipulations causing the same level of [ATP](i) and K(ATP) channel opening in both groups, suggesting a decrease during sleep and an increase during sustained wakefulness in [ATP](i) in Hcrt cells. In summary, these data demonstrate that a delicate control of activity by monitoring the availability of intracellular energy stores in Hcrt cells may serve as a novel mechanism regulating energy expenditure and behavioural state dependent upon the energy state in animals.

  20. Intracellular CHO Cell Metabolite Profiling Reveals Steady-State Dependent Metabolic Fingerprints in Perfusion Culture.

    PubMed

    Karst, Daniel J; Steinhoff, Robert F; Kopp, Marie R G; Serra, Elisa; Soos, Miroslav; Zenobi, Renato; Morbidelli, Massimo

    2016-12-20

    Perfusion cell culture processes allow the steady-state culture of mammalian cells at high viable cell density, which is beneficial for overall product yields and homogeneity of product quality in the manufacturing of therapeutic proteins. In this study, the extent of metabolic steady state and the change of the metabolite profile between different steady states of an industrial Chinese hamster ovary (CHO) cell line producing a monoclonal antibody (mAb) was investigated in stirred tank perfusion bioreactors. Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) of daily cell extracts revealed more than a hundred peaks, among which 76 metabolites were identified by tandem MS (MS/MS) and high resolution Fourier transform ion cyclotron resonance (FT-ICR) MS. Nucleotide ratios (Uridine (U)-ratio, nucleotide triphosphate (NTP)-ratio and energy charge (EC)) and multivariate analysis of all features indicated a consistent metabolite profile for a stable culture performed at 40 × 10(6) cells/mL over 26 days of culture. Conversely, the reactor was operated continuously so as to reach three distinct steady states one after the other at 20, 60, and 40 × 10(6) cells/mL. In each case, a stable metabolite profile was achieved after an initial transient phase of approximately three days at constant cell density when varying between these set points. Clear clustering according to cell density was observed by principal component analysis, indicating steady-state dependent metabolite profiles. In particular, varying levels of nucleotides, nucleotide sugar, and lipid precursors explained most of the variance between the different cell density set points. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 2016.

  1. Host Coenzyme Q Redox State Is an Early Biomarker of Thermal Stress in the Coral Acropora millepora

    PubMed Central

    Motti, Cherie A.; Miller, David J.; van Oppen, Madeleine J. H.

    2015-01-01

    Bleaching episodes caused by increasing seawater temperatures may induce mass coral mortality and are regarded as one of the biggest threats to coral reef ecosystems worldwide. The current consensus is that this phenomenon results from enhanced production of harmful reactive oxygen species (ROS) that disrupt the symbiosis between corals and their endosymbiotic dinoflagellates, Symbiodinium. Here, the responses of two important antioxidant defence components, the host coenzyme Q (CoQ) and symbiont plastoquinone (PQ) pools, are investigated for the first time in colonies of the scleractinian coral, Acropora millepora, during experimentally-induced bleaching under ecologically relevant conditions. Liquid chromatography-mass spectrometry (LC-MS) was used to quantify the states of these two pools, together with physiological parameters assessing the general state of the symbiosis (including photosystem II photochemical efficiency, chlorophyll concentration and Symbiodinium cell densities). The results show that the responses of the two antioxidant systems occur on different timescales: (i) the redox state of the Symbiodinium PQ pool remained stable until twelve days into the experiment, after which there was an abrupt oxidative shift; (ii) by contrast, an oxidative shift of approximately 10% had occurred in the host CoQ pool after 6 days of thermal stress, prior to significant changes in any other physiological parameter measured. Host CoQ pool oxidation is thus an early biomarker of thermal stress in corals, and this antioxidant pool is likely to play a key role in quenching thermally-induced ROS in the coral-algal symbiosis. This study adds to a growing body of work that indicates host cellular responses may precede the bleaching process and symbiont dysfunction. PMID:26426118

  2. Aluminium and Acrylamide Disrupt Cerebellum Redox States, Cholinergic Function and Membrane-Bound ATPase in Adult Rats and Their Offspring.

    PubMed

    Ghorbel, Imen; Amara, Ibtissem Ben; Ktari, Naourez; Elwej, Awatef; Boudawara, Ons; Boudawara, Tahia; Zeghal, Najiba

    2016-12-01

    Accumulation of aluminium and acrylamide in food is a major source of human exposure. Their adverse effects are well documented, but there is no information about the health problems arising from their combined exposure. The aim of the present study was to examine the possible neurotoxic effects after co-exposure of pregnant and lactating rats to aluminium and acrylamide in order to evaluate redox state, cholinergic function and membrane-bound ATPases in the cerebellum of adult rats and their progeny. Pregnant female rats have received aluminium (50 mg/kg body weight) via drinking water and acrylamide (20 mg/kg body weight) by gavage, either individually or in combination from the 14th day of pregnancy until day 14 after delivery. Exposure to these toxicants provoked an increase in malondialdehyde (MDA) and advanced oxidation protein product (AOPP) levels and a decrease in SOD, CAT, GPx, Na(+)K(+)-ATPase, Mg(2+)-ATPase and AChE activities in the cerebellum of mothers and their suckling pups. A reduction in GSH, NPSH and vitamin C levels was also observed. These changes were confirmed by histological results. Interestingly, co-exposure to these toxicants exhibited synergism based on physical and biochemical variables in the cerebellum of mothers and their progeny.

  3. Optical imaging of tissue mitochondrial redox state in intact rat lungs in two models of pulmonary oxidative stress

    PubMed Central

    Sepehr, Reyhaneh; Staniszewski, Kevin; Maleki, Sepideh; Jacobs, Elizabeth R.; Audi, Said

    2012-01-01

    Abstract. Ventilation with enhanced fractions of O2 (hyperoxia) is a common and necessary treatment for hypoxemia in patients with lung failure, but prolonged exposure to hyperoxia causes lung injury. Ischemia-reperfusion (IR) injury of lung tissue is common in lung transplant or crush injury to the chest. These conditions are associated with apoptosis and decreased survival of lung tissue. The objective of this work is to use cryoimaging to evaluate the effect of exposure to hyperoxia and IR injury on lung tissue mitochondrial redox state in rats. The autofluorescent mitochondrial metabolic coenzymes nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) are electron carriers in ATP generation. These intrinsic fluorophores were imaged for rat lungs using low-temperature fluorescence imaging (cryoimaging). Perfused lungs from four groups of rats were studied: normoxia (control), control perfused with an mitochondrial complex IV inhibitor (potassium cyanide, KCN), rats exposed to hyperoxia (85% O2) for seven days, and from rats subjected to lung IR in vivo 24 hours prior to study. Each lung was sectioned sequentially in the transverse direction, and the images were used to reconstruct a three-dimensional (3-D) rendering. In KCN perfused lungs the respiratory chain was more reduced, whereas hyperoxic and IR lung tissue have a more oxidized respiratory chain than control lung tissue, consistent with previously measured mitochondrial dysfunction in both hyperoxic and IR lungs. PMID:22559688

  4. The effect of citrus flavonoids on the redox state of alimentary-induced fatty liver in rats.

    PubMed

    Rapavi, E; Kocsis, I; Fehér, E; Szentmihályi, K; Lugasi, A; Székely, E; Blázovics, A

    2007-03-01

    Both chronic venous insufficiency (CVI) and fatty liver may develop at the same time. Hesperidin and diosmin are used for the treatment CVI. There is no information, however, on the effect of these flavonoids in the redox state of fatty liver. In this study, male Wistar albino rats were fed a lipid-rich diet with or without 450 mg diosmin-50 mg hesperidin-containing drug (60 mg kg(-1) body weight/day, per os) for 9 days to determine the impact of treatment on antioxidant defence system of the fatty liver. We detected free SH-group concentration (SHC), hydrogen-donating ability (HDA), and natural scavenger capacity were decreased and hepatic malonaldehyde content and dien conjugate (DC) content in rats with fatty liver were increased compared to the control. After treatment in fatty liver, these parameters (except DC) significantly improved and approached the control value. Our results indicate that diosmin-hesperidin-containing drug may be a useful agent in improving the antioxidant defensive system in alimentary-induced fatty liver disease.

  5. Cyclic denaturation and renaturation of double-stranded DNA by redox-state switching of DNA intercalators.

    PubMed

    Syed, Shahida N; Schulze, Holger; Macdonald, Daniel; Crain, Jason; Mount, Andrew R; Bachmann, Till T

    2013-04-10

    Hybridization of complementary nucleic acid strands is fundamental to nearly all molecular bioanalytical methods ranging from polymerase chain reaction and DNA biosensors to next generation sequencing. For nucleic acid amplification methods, controlled DNA denaturation and renaturation is particularly essential and achieved by cycling elevated temperatures. Although this is by far the most used technique, the management of rapid temperature changes requires bulky instrumentation and intense power supply. These factors so far precluded the development of true point-of-care tests for molecular diagnostics. To overcome this limitation we explored the possibility of using electrochemical means to control reversible DNA hybridization by using the electroactive intercalator daunomycin (DM). We show that redox-state switching of DM altered its properties from DNA binding to nonbinding, under otherwise constant conditions, and thus altered the thermodynamic stability of duplex DNA. The operational principle was demonstrated using complementary synthetic 20mer and 40mer DNA oligonucleotides. Absorbance-based melting curve analysis revealed significantly higher melting temperatures for DNA in the presence of oxidized compared to chemically reduced DM. This difference was exploited to drive cyclic electrochemically controlled denaturation and renaturation. Analysis with in situ UV-vis and circular dichroism spectroelectrochemistry, as two independent techniques, indicated that up to 80% of the DNA was reversibly hybridized. This remarkable demonstration of electrochemical control of five cycles of DNA denaturation and renaturation, under otherwise constant conditions, could have wide-ranging implications for the future development of miniaturized analytical systems for molecular diagnostics and beyond.

  6. Optical imaging of tissue mitochondrial redox state in intact rat lungs in two models of pulmonary oxidative stress

    NASA Astrophysics Data System (ADS)

    Sepehr, Reyhaneh; Staniszewski, Kevin; Maleki, Sepideh; Jacobs, Elizabeth R.; Audi, Said; Ranji, Mahsa

    2012-04-01

    Ventilation with enhanced fractions of O2 (hyperoxia) is a common and necessary treatment for hypoxemia in patients with lung failure, but prolonged exposure to hyperoxia causes lung injury. Ischemia-reperfusion (IR) injury of lung tissue is common in lung transplant or crush injury to the chest. These conditions are associated with apoptosis and decreased survival of lung tissue. The objective of this work is to use cryoimaging to evaluate the effect of exposure to hyperoxia and IR injury on lung tissue mitochondrial redox state in rats. The autofluorescent mitochondrial metabolic coenzymes nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) are electron carriers in ATP generation. These intrinsic fluorophores were imaged for rat lungs using low-temperature fluorescence imaging (cryoimaging). Perfused lungs from four groups of rats were studied: normoxia (control), control perfused with an mitochondrial complex IV inhibitor (potassium cyanide, KCN), rats exposed to hyperoxia (85% O2) for seven days, and from rats subjected to lung IR in vivo 24 hours prior to study. Each lung was sectioned sequentially in the transverse direction, and the images were used to reconstruct a three-dimensional (3-D) rendering. In KCN perfused lungs the respiratory chain was more reduced, whereas hyperoxic and IR lung tissue have a more oxidized respiratory chain than control lung tissue, consistent with previously measured mitochondrial dysfunction in both hyperoxic and IR lungs.

  7. All solid-state redox supercapacitors based on supramolecular 1,5-diaminoanthraquinone oligomeric electrode and polymeric electrolytes

    NASA Astrophysics Data System (ADS)

    Hashmi, S. A.; Suematsu, Shunzo; Naoi, Katsuhiko

    Supramolecular conducting oligomeric 1,5-diaminoanthraquinone (DAAQ)-based all solid-state redox supercapacitors have been fabricated with the solid polymer electrolyte, poly vinyl alcohol (PVA)-H 3PO 4 blend and polymeric gel electrolyte poly methyl methacrylate (PMMA)-ethylene carbonate (EC)-propylene carbonate (PC)-tetra ethyl ammonium perchlorate (TEAClO 4) system. The films of gel electrolyte of the optimized composition PMMA (35 wt.%)-EC:PC (1:1 v/v)-1 M TEAClO 4 and polymer electrolyte PVA-H 3PO 4 (50:50 w/w) blend exhibited high ionic conductivity (10 -4 to 10 -3 S cm -1 at room temperature) with good mechanical strength, suitable for application in electrochemical supercapacitors. The capacitors have been characterized using a.c. impedance spectroscopy, linear sweep voltammetry and prolonged cyclic test. The maximum capacitance value of 3.7-5.4 mF cm -2 (equivalent to single electrode capacitance 125-184 F g -1 of DAAQ electrode) has been observed for the PMMA-gel electrolyte based capacitor. This corresponds to the energy density 92-135 Wh kg -1. System based on the proton-conducting PVA-H 3PO 4 polymer blend, however has relatively lower capacitance of 1.1-4.0 mF cm -2 (equivalent to single electrode capacitance of 36-136 F g -1).

  8. Chloroplast DNA Replication Is Regulated by the Redox State Independently of Chloroplast Division in Chlamydomonas reinhardtii1[C][OA

    PubMed Central

    Kabeya, Yukihiro; Miyagishima, Shin-ya

    2013-01-01

    Chloroplasts arose from a cyanobacterial endosymbiont and multiply by division. In algal cells, chloroplast division is regulated by the cell cycle so as to occur only once, in the S phase. Chloroplasts possess multiple copies of their own genome that must be replicated during chloroplast proliferation. In order to examine how chloroplast DNA replication is regulated in the green alga Chlamydomonas reinhardtii, we first asked whether it is regulated by the cell cycle, as is the case for chloroplast division. Chloroplast DNA is replicated in the light and not the dark phase, independent of the cell cycle or the timing of chloroplast division in photoautotrophic culture. Inhibition of photosynthetic electron transfer blocked chloroplast DNA replication. However, chloroplast DNA was replicated when the cells were grown heterotrophically in the dark, raising the possibility that chloroplast DNA replication is coupled with the reducing power supplied by photosynthesis or the uptake of acetate. When dimethylthiourea, a reactive oxygen species scavenger, was added to the photoautotrophic culture, chloroplast DNA was replicated even in the dark. In contrast, when methylviologen, a reactive oxygen species inducer, was added, chloroplast DNA was not replicated in the light. Moreover, the chloroplast DNA replication activity in both the isolated chloroplasts and nucleoids was increased by dithiothreitol, while it was repressed by diamide, a specific thiol-oxidizing reagent. These results suggest that chloroplast DNA replication is regulated by the redox state that is sensed by the nucleoids and that the disulfide bonds in nucleoid-associated proteins are involved in this regulatory activity. PMID:23447524

  9. Solution and solid-state characterization of Eu(II) chelates: a possible route towards redox responsive MRI contrast agents.

    PubMed

    Burai, L; Tóth, E; Seibig, S; Scopelliti, R; Merbach, A E

    2000-10-16

    We report the first solid state X-ray crystal structure for a Eu(II) chelate, [C(NH2)3]3[Eu(II)(DTPA)(H2O)].8H2O, in comparison with those for the corresponding Sr analogue, [C(NH2)3]3[Sr(DTPA)(H2O).8H2O and for [Sr(ODDA)].8H2O (DTPA5 = diethylenetriamine-N,N,N',N",N"-pentaacetate, ODDA2- =1,4,10,13-tetraoxa-7,16-diazacyclooctadecane-7,16-diacetate ). The two DTPA complexes are isostructural due to the similar ionic size and charge of Sr(2+) and Eu(2+). The redox stability of [Eu(II)(ODDA)(H2O)] and [Eu(II)(ODDM)]2- complexes has been investigated by cyclovoltammetry and UV/Vis spectrophotometry (ODDM4- =1,4,10,13-tetraoxa-7,16-diaza-cyclooctadecane-7,16-++ +dimalonate). The macrocyclic complexes are much more stable against oxidation than [Eu(II)(DTPA)(H2O)]3- (the redox potentials are E1/2 =-0.82 V, -0.92 V, and -1.35 V versus Ag/AgCl electrode for [Eu(III/II)(ODDA)(H2O)],[Eu(III/II)(ODDM)], and [Eu(III/II)(DTPA)(H2O)], respectively, compared with -0.63 V for Eu(III/II) aqua). The thermodynamic stability constants of [Eu(II)(ODDA)(H2O)], [Eu(II)(ODDM)]2-, [Sr(ODDA)(H2O)], and [Sr(ODDM)]2- were also determined by pH potentiometry. They are slightly higher for the EuII complexes than those for the corresponding Sr analogues (logK(ML)=9.85, 13.07, 8.66, and 11.34 for [Eu(II)(ODDA)(H2O)], [Eu(II)(ODDM)]2-, [Sr(ODDA)(H2O)], and [Sr(ODDM)]2-, respectively, 0.1M (CH3)4NCl). The increased thermodynamic and redox stability of the Eu(II) complex formed with ODDA as compared with the traditional ligand DTPA can be of importance when biomedical application is concerned. A variable-temperature 17O-NMR and 1H-nuclear magnetic relaxation dispersion (NMRD) study has been performed on [Eu(II)(ODDA)(H2O)] and [Eu(II)(ODDM)]2- in aqueous solution. [Eu(II)(ODDM)]2- has no inner-sphere water molecule which allowed us to use it as an outer-sphere model for [Eu(II)(ODDA)(H2O)]. The water exchange rate (k298(ex)= 0.43 x 10(9)s(-1)) is one third of that obtained for [Eu(II)(DTPA)(H2O)]3

  10. Quantitative measurement of redox potential in hypoxic cells using SERS nanosensors

    NASA Astrophysics Data System (ADS)

    Jiang, Jing; Auchinvole, Craig; Fisher, Kate; Campbell, Colin J.

    2014-09-01

    Hypoxia is considered to be a reductive disorder of cells that is caused either by a lack of oxygen or by the dysregulation of metabolic pathways and is thought to play a role in the pathology of diseases including stroke and cancer. One aspect of hypoxia that remains poorly investigated is the dysregulation of cellular redox potential and its role in controlling biological pathway activation. Since there is currently no way of quantitatively measuring the intracellular redox potential of hypoxic cells, this provided us with the motivation to develop optical nanosensors whose Surface-Enhanced Raman (SER) spectrum provides a quantitative measure of redox potential in hypoxic cells. Our nanosensors are made from organic reporter molecules that show oxidation-state-dependent changes in the Raman spectrum and are chemically adsorbed onto gold nanoshells. These nanosensors can be taken up by cells, and by collecting the SER spectrum we can calculate the localised intracellular redox potential from single hypoxic cells in a non-invasive, reversible way.Hypoxia is considered to be a reductive disorder of cells that is caused either by a lack of oxygen or by the dysregulation of metabolic pathways and is thought to play a role in the pathology of diseases including stroke and cancer. One aspect of hypoxia that remains poorly investigated is the dysregulation of cellular redox potential and its role in controlling biological pathway activation. Since there is currently no way of quantitatively measuring the intracellular redox potential of hypoxic cells, this provided us with the motivation to develop optical nanosensors whose Surface-Enhanced Raman (SER) spectrum provides a quantitative measure of redox potential in hypoxic cells. Our nanosensors are made from organic reporter molecules that show oxidation-state-dependent changes in the Raman spectrum and are chemically adsorbed onto gold nanoshells. These nanosensors can be taken up by cells, and by collecting the SER

  11. Evolutionary Acquisition of Cysteines Determines FOXO Paralog-Specific Redox Signaling

    PubMed Central

    Putker, Marrit; Vos, Harmjan R.; van Dorenmalen, Kim; de Ruiter, Hesther; Duran, Ana G.; Snel, Berend; Burgering, Boudewijn M.T.; Vermeulen, Michiel

    2015-01-01

    Abstract Reduction–oxidation (redox) signaling, the translation of an oxidative intracellular environment into a cellular response, is mediated by the reversible oxidation of specific cysteine thiols. The latter can result in disulfide formation between protein hetero- or homodimers that alter protein function until the local cellular redox environment has returned to the basal state. We have previously shown that this mechanism promotes the nuclear localization and activity of the Forkhead Box O4 (FOXO4) transcription factor. Aims: In this study, we sought to investigate whether redox signaling differentially controls the human FOXO3 and FOXO4 paralogs. Results: We present evidence that FOXO3 and FOXO4 have acquired paralog-specific cysteines throughout vertebrate evolution. Using a proteome-wide screen, we identified previously unknown redox-dependent FOXO3 interaction partners. The nuclear import receptors Importin-7 (IPO7) and Importin-8 (IPO8) form a disulfide-dependent heterodimer with FOXO3, which is required for its reactive oxygen species-induced nuclear translocation. FOXO4 does not interact with IPO7 or IPO8. Innovation and Conclusion: IPO7 and IPO8 control the nuclear import of FOXO3, but not FOXO4, in a redox-sensitive and disulfide-dependent manner. Our findings suggest that evolutionary acquisition of cysteines has contributed to regulatory divergence of FOXO paralogs, and that phylogenetic analysis can aid in the identification of cysteines involved in redox signaling. Antioxid. Redox Signal. 22, 15–28. PMID:25069953

  12. Investigation of multi-state charge-storage properties of redox-active organic molecules in silicon-molecular hybrid devices for DRAM and Flash applications

    NASA Astrophysics Data System (ADS)

    Gowda, Srivardhan Shivappa

    Molecular electronics has recently spawned a considerable amount of interest with several molecules possessing charge-conduction and charge-storage properties proposed for use in electronic devices. Hybrid silicon-molecular technology has the promise of augmenting the current silicon technology and provide for a transitional path to future molecule-only technology. The focus of this dissertation work has been on developing a class of hybrid silicon-molecular electronic devices for DRAM and Flash memory applications utilizing redox-active molecules. This work exploits the ability of molecules to store charges with single-electron precision at room temperature. The hybrid devices are fabricated by forming self-assembled monolayers of redox-active molecules on Si and oxide (SiO2 and HfO2) surfaces via formation of covalent linkages. The molecules possess discrete quantum states from which electrons can tunnel to the Si substrate at discrete applied voltages (oxidation process, cell write), leaving behind a positively charged layer of molecules. The reduction (erase) process, which is the process of electrons tunneling back from Si to the molecules, neutralizes the positively charged molecular monolayer. Hybrid silicon-molecular capacitor test structures were electrically characterized with an electrolyte gate using cyclic voltammetry (CyV) and impedance spectroscopy (CV) techniques. The redox voltages, kinetics (write/erase speeds) and charge-retention characteristics were found to be strongly dependent on the Si doping type and densities, and ambient light. It was also determined that the redox energy states in the molecules communicate with the valence band of the Si substrate. This allows tuning of write and read states by modulating minority carriers in n- and p-Si substrates. Ultra-thin dielectric tunnel barriers (SiO2, HfO2) were placed between the molecules and the Si substrate to augment charge-retention for Flash memory applications. The redox response was

  13. Opinion: the red-light response of stomatal movement is sensed by the redox state of the photosynthetic electron transport chain.

    PubMed

    Busch, Florian A

    2014-02-01

    Guard cells regulate CO2 uptake and water loss of a leaf by controlling stomatal movement in response to environmental factors such as CO2, humidity, and light. The mechanisms by which stomata respond to red light are actively debated in the literature, and even after decades of research it is still controversial whether stomatal movement is related to photosynthesis or not. This review summarizes the current knowledge of the red-light response of stomata. A comparison of published evidence suggests that stomatal movement is controlled by the redox state of photosynthetic electron transport chain components, in particular the redox state of plastoquinone. Potential consequences for the modeling of stomatal conductance are discussed.

  14. The redox state of the mantle during and just after core formation.

    PubMed

    Frost, D J; Mann, U; Asahara, Y; Rubie, D C

    2008-11-28

    Siderophile elements are depleted in the Earth's mantle, relative to chondritic meteorites, as a result of equilibration with core-forming Fe-rich metal. Measurements of metal-silicate partition coefficients show that mantle depletions of slightly siderophile elements (e.g. Cr, V) must have occurred at more reducing conditions than those inferred from the current mantle FeO content. This implies that the oxidation state (i.e. FeO content) of the mantle increased with time as accretion proceeded. The oxygen fugacity of the present-day upper mantle is several orders of magnitude higher than the level imposed by equilibrium with core-forming Fe metal. This results from an increase in the Fe2O3 content of the mantle that probably occurred in the first 1Ga of the Earth's history. Here we explore fractionation mechanisms that could have caused mantle FeO and Fe2O3 contents to increase while the oxidation state of accreting material remained constant (homogeneous accretion). Using measured metal-silicate partition coefficients for O and Si, we have modelled core-mantle equilibration in a magma ocean that became progressively deeper as accretion proceeded. The model indicates that the mantle would have become gradually oxidized as a result of Si entering the core. However, the increase in mantle FeO content and oxygen fugacity is limited by the fact that O also partitions into the core at high temperatures, which lowers the FeO content of the mantle. (Mg,Fe)(Al,Si)O3 perovskite, the dominant lower mantle mineral, has a strong affinity for Fe2O3 even in the presence of metallic Fe. As the upper mantle would have been poor in Fe2O3 during core formation, FeO would have disproportionated to produce Fe2O3 (in perovskite) and Fe metal. Loss of some disproportionated Fe metal to the core would have enriched the remaining mantle in Fe2O3 and, if the entire mantle was then homogenized, the oxygen fugacity of the upper mantle would have been raised to its present-day level.

  15. Redox Control of Renal Function and Hypertension

    PubMed Central

    Whaley-Connell, Adam; Sowers, James R.

    2008-01-01

    Abstract Loss of redox homeostasis and formation of excessive free radicals play an important role in the pathogenesis of kidney disease and hypertension. Free radicals such as reactive oxygen species (ROS) are necessary in physiologic processes. However, loss of redox homeostasis contributes to proinflammatory and profibrotic pathways in the kidney, which in turn lead to reduced vascular compliance and proteinuria. The kidney is susceptible to the influence of various extracellular and intracellular cues, including the renin–angiotensin–aldosterone system (RAAS), hyperglycemia, lipid peroxidation, inflammatory cytokines, and growth factors. Redox control of kidney function is a dynamic process with reversible pro– and anti-free radical processes. The imbalance of redox homeostasis within the kidney is integral in hypertension and the progression of kidney disease. An emerging paradigm exists for renal redox contribution to hypertension. Antioxid. Redox Signal. 11, 2047–2089. PMID:18821850

  16. The Oxidation State of Komatiites and the Redox History of the Mantle

    NASA Astrophysics Data System (ADS)

    Nicklas, R. W.; Puchtel, I. S.; Ash, R. D.

    2015-12-01

    Oxygen fugacity (fO2) is an important intensive variable in magmatic systems. Previous studies argued that, at the level of resolution of ca. 1.0 ΔNNO log units, the mantle has been at a near-constant oxidation state since core formation [1,3]. Here, we revisit this hypothesis using the V partitioning between olivine or chromite and komatiite liquid as oxybarometers [1,2] by obtaining high-precision V abundance data for komatiite lava flows. Whole-rock samples collected across each lava flow were analyzed for V and other transition metal abundances using Standard Addition ICP-MS (SA ICP-MS); liquidus olivines and chromites were analyzed using Laser Ablation ICP-MS. Our external precision for V concentrations is 5% (2SD) for SA-ICP-MS, based on replicate analysis of standard reference materials. The V data, when plotted against wt.% MgO, define regression lines consistent with olivine control for V. Linear regressions through the V vs. MgO data for samples for each flow were used to determine V content of the emplaced lavas using known MgO contents. Calculated partition coefficients for V were used to determine the oxygen fugacity of each komatiite system using experimental calibrations of [1,2] with a precision of 0.10 - 0.05 ΔNNO log units (2SE). The calculated oxygen fugacities show a well-defined trend of increasing fO2 (>0.5 ΔNNO log units) over ~1.0 Ga of Earth's history, approaching that of modern mantle at 2.4 Ga, immediately before the Great Oxidation Event (GOE). An exception is the 3.55 Ga Schapenburg komatiite, which plots 0.5 log units above the trend, likely reflecting primordial mantle heterogeneity. Our data suggest that the mantle was becoming increasingly oxidized leading up to the GOE. A change in deep Earth buffering capacity could change the oxidation state of volcanic gases, triggering the rise in atmospheric O2 at 2.4 Ga. [1] Canil (1997) Nature 389. [2] Canil, 1999; [3] Li et al. (2004) EPSL 228. Oxygen fugacity (fO2) is an important

  17. Overexpression of plastid terminal oxidase in Synechocystis sp. PCC 6803 alters cellular redox state.

    PubMed

    Feilke, Kathleen; Ajlani, Ghada; Krieger-Liszkay, Anja

    2017-09-26

    Cyanobacteria are the most ancient organisms performing oxygenic photosynthesis, and they are the ancestors of plant plastids. All plastids contain the plastid terminal oxidase (PTOX), while only certain cyanobacteria contain PTOX. Many putative functions have been discussed for PTOX in higher plants including a photoprotective role during abiotic stresses like high light, salinity and extreme temperatures. Since PTOX oxidizes PQH2 and reduces oxygen to water, it is thought to protect against photo-oxidative damage by removing excess electrons from the plastoquinone (PQ) pool. To investigate the role of PTOX we overexpressed rice PTOX fused to the maltose-binding protein (MBP-OsPTOX) in Synechocystis sp. PCC 6803, a model cyanobacterium that does not encode PTOX. The fusion was highly expressed and OsPTOX was active, as shown by chlorophyll fluorescence and P700 absorption measurements. The presence of PTOX led to a highly oxidized state of the NAD(P)H/NAD(P)(+) pool, as detected by NAD(P)H fluorescence. Moreover, in the PTOX overexpressor the electron transport capacity of PSI relative to PSII was higher, indicating an alteration of the photosystem I (PSI) to photosystem II (PSII) stoichiometry. We suggest that PTOX controls the expression of responsive genes of the photosynthetic apparatus in a different way from the PQ/PQH2 ratio.This article is part of the themed issue 'Enhancing photosynthesis in crop plants: targets for improvement'. © 2017 The Author(s).

  18. Redox States of Initial Atmospheres Outgassed on Rocky Planets and Planetesimals

    NASA Astrophysics Data System (ADS)

    Schaefer, Laura; Fegley, Bruce, Jr.

    2017-07-01

    The Earth and other rocky planets and planetesimals in the solar system formed through the mixing of materials from various radial locations in the solar nebula. This primordial material likely had a range of oxidation states as well as bulk compositions and volatile abundances. We investigate the oxygen fugacity produced by the outgassing of mixtures of solid meteoritic material, which approximate the primitive nebular materials. We find that the gas composition and oxygen fugacity of binary and ternary mixtures of meteoritic materials vary depending on the proportion of reduced versus oxidized material, and also find that mixtures using differentiated materials do not show the same oxygen fugacity trends as those using similarly reduced but undifferentiated materials. We also find that simply mixing the gases produced by individual meteoritic materials together does not correctly reproduce the gas composition or oxygen fugacity of the binary and ternary mixtures. We provide tabulated fits for the oxygen fugacities of all of the individual materials and binary mixtures that we investigate. These values may be useful in planetary formation models, models of volatile transport on planetesimals or meteorite parent bodies, or models of trace element partitioning during metal-silicate fractionation.

  19. Application of Quasi-Steady-State Methods to Nonlinear Models of Intracellular Transport by Molecular Motors.

    PubMed

    Zmurchok, Cole; Small, Tim; Ward, Michael J; Edelstein-Keshet, Leah

    2017-07-13

    Molecular motors such as kinesin and dynein are responsible for transporting material along microtubule networks in cells. In many contexts, motor dynamics can be modelled by a system of reaction-advection-diffusion partial differential equations (PDEs). Recently, quasi-steady-state (QSS) methods have been applied to models with linear reactions to approximate the behaviour of the full PDE system. Here, we extend this QSS reduction methodology to certain nonlinear reaction models. The QSS method relies on the assumption that the nonlinear binding and unbinding interactions of the cellular motors occur on a faster timescale than the spatial diffusion and advection processes. The full system dynamics are shown to be well approximated by the dynamics on the slow manifold. The slow manifold is parametrized by a single scalar quantity that satisfies a scalar nonlinear PDE, called the QSS PDE. We apply the QSS method to several specific nonlinear models for the binding and unbinding of molecular motors, and we use the resulting approximations to draw conclusions regarding the parameter dependence of the spatial distribution of motors for these models.

  20. Stable Chromium Isotopes as tracer of changes in weathering processes and redox state of the ocean during Neoproterozoic glaciation

    NASA Astrophysics Data System (ADS)

    Dossing, L. N.; Gaucher, C.; Boggiani, P. C.; Frei, R.

    2010-12-01

    The chemistry of surface environments on Earth has essentially evolved from early anoxic conditions to a present day oxic state. How in detail this transition occurred is still a matter of debate but the last 200 million years (My) of the Neoproterozoic Era [(1000 to 542 million years ago (Ma)] show an emerging picture of large scale fluctuations in the redox state of the oceans [1-2]. The reasons for these fluctuations are to be sought in Earth’s atmospheric oxygenation which led to the rapid radiation of oxygen-utilizing macroscopic metazoans, but details regarding the nature of these fluctuations remain unclear. The Late Neoproterozoic is known for a number of widespread glaciations causing the return of ferruginous oceans which were absent for more than a billion years of Earth history. This study elaborates on the idea that Chromium (Cr) stable isotopes in Fe-rich chemical sediments deposited during glacial events are suitable for tracing oxygenation of surface environments through Earth's history [3]. The focus of this study is to apply the Cr isotope system to one of the Marinoan (650-630 Ma) glacio-marine sequences (Jacadigo Group, Brazil) in order to get a detailed spatial and relative temporal resolution of changes in weathering processes and redox states of the respective ocean basin during the depositional period of the sediments. The Jacadigo Group is a glacio-marine succession which is composed of the Urucum Fm. (sandstones) at the base, the Santa Cruz Fm. (BIFs) and the Puga Fm. (Fe-rich glacial diamictites) at the top. Cr stable isotope measurements on various BIF horizons of the Santa Cruz Fm. yielded positive δ53/52Cr values range from +0.4 to+ 0.9‰, while the overlying Fe-rich glaciogenic diamictites of the Puga Fm. show δ53/52Cr values range from to +0.1 to+ 0.4‰. These positively fractionated values correspond to positive δ53/52Cr values measured in other Late Neoproterozoic BIFs and speak for the occurrence of potential oxygenation

  1. Inhibition of intramolecular electron transfer in ascorbate oxidase by Ag+: redox state dependent binding.

    PubMed

    Santagostini, Laura; Gullotti, Michele; Hazzard, James T; Maritano, Silvana; Tollin, Gordon; Marchesini, Augusto

    2005-02-01

    Intramolecular electron transfer within zucchini squash ascorbate oxidase is inhibited in a novel manner in the presence of an equimolar concentration of Ag(+). At pH 5.5 in acetate buffer reduction of the enzyme by laser flash photolytically generated 5-deazariboflavin semiquinone occurs at the Type I Cu with a rate constant of 5 x 10(8) M(-1)s(-1). Subsequent to this initial reduction step, equilibration of the reducing equivalent between the Type I Cu and the trinuclear Type II, III copper cluster (TNC) occurs with rate constant of 430 s(-1). The 41% of the reduced Type I Cu is oxidized by this intramolecular electron transfer reaction. When these reactions are performed in the presence of Ag(+) equimolar to dimeric AO, the bimolecular reduction of the enzyme by the 5-deazariboflavin semiquinone is not affected. As in the case of the native enzyme, intramolecular electron transfer between the Type I Cu and the TNC occurs, which continues until 25% of the reducing equivalent has been transferred. At that point, the reducing equivalent is observed to more slowly return to the Type I Cu, resulting a second reduction phase whose rate constant (100 s(-1)) is protein and Ag(+) concentration independent. The data suggest that partial reduction of the TNC results in Ag(+) binding to the enzyme which causes the apparent midpoint potential of the TNC as a whole to decrease thereby reversing the direction of electron flow. These results are consistent with the inhibitory effect of Ag(+) on the steady-state activity of ascorbate oxidase [S. Maritano, E. Malusa, A. Marchesini, presented at The Meeting on Metalloproteins, SERC Daresbury Laboratory, Warrington, England, 1992; A. Marchesini, XIX Convegno Nazionale SICA, Italian Society of Agricultural Chemistry, Reggio Calabria, Italy, September 2001.].

  2. Effects of pent-4-enoate on cellular redox state, glycolysis and fatty acid oxidation in isolated perfused rat heart

    PubMed Central

    Hiltunen, J. Kalervo; Jauhonen, V. Pekka; Savolainen, Markku J.; Hassinen, Ilmo E.

    1978-01-01

    The metabolic effects of pent-4-enoate were studied in beating and potassium-arrested perfused rat hearts. The addition of 0.8mm-pent-4-enoate to the fluid used to perfuse a potassium-arrested heart resulted in a 70% increase in the O2 consumption and a 66% decrease in the glycolytic flux as measured in terms of the de-tritiation of [3-3H]glucose, although the proportion of the O2 consumption attributable to glucose oxidation decreased from an initial 30% to 10%. The pent-4-enoate-induced increase in O2 consumption was only 15% in the beating heart. In the potassium-arrested heart, pent-4-enoate stimulated palmitate oxidation by more than 100% when measured in terms of the production of 14CO2 from [1-14C]palmitate, but in the beating heart palmitate oxidation was inhibited. Perfusion of the heart with pent-4-enoate had no effect on the proportion of pyruvate dehydrogenase found in the active form, in spite of large changes in the CoASH and acetyl-CoA concentrations and changes in their concentration ratios. The effects of pent-4-enoate on the cellular redox state were dependent on the ATP consumption of the heart. In the beating heart, pent-4-enoate caused a rapid mitochondrial NAD+ reduction that subsequently faded out, so that the final state was more oxidized than the initial state. The arrested heart, however, remained in a more reduced state than initially, even after the partial re-oxidation that followed the initial rapid NAD+ reduction. The ability of pent-4-enoate to increase or decrease fatty acid oxidation can be explained on the basis of the differential effects of pent-4-enoate on the concentration of citric acid-cycle intermediates under conditions of high or low ATP consumption of the myocardial cell. The proportion of the fatty acids in the fuel consumed by the heart is probably primarily determined by the regulatory mechanisms of glycolysis. When pent-4-enoate causes an increase in the citric acid-cycle intermediates, feedback inhibition of

  3. Altered apoplastic ascorbate redox state in tobacco plants via ascorbate oxidase overexpression results in delayed dark-induced senescence in detached leaves.

    PubMed

    Fotopoulos, Vasileios; Kanellis, Angelos K

    2013-12-01

    Ascorbate oxidase (AO) is an apoplastic enzyme that uses oxygen to catalyse the oxidation of ascorbate (AA) to dehydroascorbate (DHA) via the unstable radical monodehydroascorbate (MDHA). Here, we report that transgenic tobacco plants (Nicotiana tabacum L. cv. Xanthi) with an in vivo lowered apoplastic AA redox state through increased AO expression demonstrate signs of delayed dark-induced senescence compared with wild-type plants, as shown by chlorophyll loss assay. In situ localization of hydrogen peroxide (H2O2) suggests that, although transgenic plants have higher constitutive levels of H2O2 under normal growth conditions, imposed dark-induced senescence results in smaller induction levels of H2O2, an observation which correlates with increased antioxidant enzyme activities and an induction in the expression of AA recycling genes compared with that in wild-type plants. Our current findings, combined with previous studies which showed the contribution of AO in the regulation of AA redox state, suggest that the reduction in AA redox state in the leaf apoplast of these transgenic plants results in an increase in the endogenous levels of H2O2, which provides a form of 'acquired tolerance' to oxidative stress imposed by dark-induced senescence.

  4. OxyR2 Functions as a Three-state Redox Switch to Tightly Regulate Production of Prx2, a Peroxiredoxin of Vibrio vulnificus.

    PubMed

    Bang, Ye-Ji; Lee, Zee-Won; Kim, Dukyun; Jo, Inseong; Ha, Nam-Chul; Choi, Sang Ho

    2016-07-29

    The bacterial transcriptional regulator OxyR is known to function as a two-state redox switch. OxyR senses cellular levels of H2O2 via a "sensing cysteine" that switches from the reduced to a disulfide state upon H2O2 exposure, inducing the expression of antioxidant genes. The reduced and disulfide states of OxyR, respectively, bind to extended and compact regions of DNA, where the reduced state blocks and the oxidized state allows transcription and further induces target gene expression by interacting with RNA polymerase. Vibrio vulnificus OxyR2 senses H2O2 with high sensitivity and induces the gene encoding the antioxidant Prx2. In this study, we used mass spectrometry to identify a third redox state of OxyR2, in which the sensing cysteine was overoxidized to S-sulfonated cysteine (Cys-SO3H) by high H2O2 in vitro and in vivo, where the modification deterred the transcription of prx2 The DNA binding preferences of OxyR25CA-C206D, which mimics overoxidized OxyR2, suggested that overoxidized OxyR2 binds to the extended DNA site, masking the -35 region of the prx2 promoter. These combined results demonstrate that OxyR2 functions as a three-state redox switch to tightly regulate the expression of prx2, preventing futile production of Prx2 in cells exposed to high levels of H2O2 sufficient to inactivate Prx2. We further provide evidence that another OxyR homolog, OxyR1, displays similar three-state behavior, inviting further exploration of this phenomenon as a potentially general regulatory mechanism.

  5. Redox State of the Deep Ocean During the 2.22-2.1 Ga Carbon Isotope Excursion

    NASA Astrophysics Data System (ADS)

    Bekker, A.; Shen, Y.; Scott, C.; Kacanda, M.; Lyons, T.; Kenig, F.; Anbar, A.; Rouxel, O.

    2006-05-01

    Response of the redox state of the deep ocean to the rise of atmospheric oxygen, as well as the 2.22-2.1 Ga carbon isotope excursion that followed, is not known. The c. 2.15 Ga Sengoma Argillite Formation (SAF), Botswana, is correlative with the Silverton Formation (SF), South Africa, which contains carbonates with δ °13°C values ranging from +8.3 to +11.3 ‰ PDB. Both units were deposited along the northern margin of the Kaapvaal Craton in an open-marine environment. The SAF consists of two upward- shallowing cycles with organic-rich sulfidic shales deposited in subtidal settings at the base and red beds deposited in coastal and fluvial settings at the top. Sulfur isotope data show a large range from -21.3 to +13.7 ‰ V-CDT with highly negative values confined to the lower part of the cycles and positive values to the upper part of the cycles. The Fe speciation data show similar stratigraphic trends. Carbon isotope values of organic matter are as low as -33.7 ‰ PDB, and if compared with carbonate carbon isotope record of the correlative SF, suggest significant contribution from secondary productivity via either sulfur or methane oxidation. Mo concentrations in these organic-rich shales are just above crustal levels. These data suggest deep ocean euxinic conditions during the carbon isotope excursion. Fe isotope data for sulfides from these shales show an unusually narrow range of Fe isotope values relative to other Archean and Paleoproterozoic sulfides. These data fall within the range of the hydrothermal iron flux, suggesting complete Fe reduction and precipitation as sulfide in the deep ocean. The 2.1-2.0 Ga Ludikovian black shales, Russia, were also deposited in an open marine and euxinic environment but contain much higher Mo levels up to 74 ppm and sulfides with Fe isotope values ranging from those of hydrothermal Fe flux to highly positive values. Higher Mo concentrations in these shales suggest that significant part of the ocean was not a sink for Mo

  6. Effects of chronic elevated ozone concentration on the redox state and fruit yield of red pepper plant Capsicum baccatum.

    PubMed

    Bortolin, Rafael Calixto; Caregnato, Fernanda Freitas; Divan, Armando Molina; Reginatto, Flávio Henrique; Gelain, Daniel Pens; Moreira, José Cláudio Fonseca

    2014-02-01

    Ozone (O3) is one of the most harmful air pollutants to crops, contributing to high losses on crop yield. Tropospheric O3 background concentrations have increased since pre-industrial times reaching phytotoxic concentrations in many world regions. Capsicum peppers are the second most traded spice in the world, but few studies concerning the O3 effects in this genus are known. Thereby, the aim of this work was to evaluate the effects of chronic exposure to elevated O3 concentrations in red pepper plant Capsicum baccatum L. var. pendulum with especial considerations on the leaf redox state and fruit yield. Fifteen C. baccatum plants were exposed to O3 in open-top chambers during fruit ripening (62 days) at a mean concentration of 171.6 µg/m(3) from 10:00 am to 4:00 pm. We found that O3 treated plants significantly decreased the amount and the total weight of fruits, which were probably a consequence of the changes on leaf oxidative status induced by ozone exposure. Ozone exposed plants increased the reactive oxygen species (ROS) levels on the leaves, which may be associated with the observed decrease on the activity of enzymatic antioxidant defense system, as well with lower levels of polyphenol and reduced thiol groups. Enhanced ROS production and the direct O3 reaction lead to biomacromolecules damages as seen in the diminished chlorophyll content and in the elevated lipid peroxidation and protein carbonylation levels. Through a correlation analysis it was possible to observe that polyphenols content was more important to protect pepper plants against oxidative damages to lipids than to proteins.

  7. Hydroperoxides can modulate the redox state of pyridine nucleotides and the calcium balance in rat liver mitochondria

    PubMed Central

    Lötscher, Hans Ruedi; Winterhalter, Kaspar H.; Carafoli, Ernesto; Richter, Christoph

    1979-01-01

    When rats are fed a selenium-deficient diet, the glutathione peroxidase activity in liver mitochondria decreases within 5 weeks to 0-6% of that of control animals fed on a diet supplemented with 0.5 ppm of selenium as sodium selenite. Analysis of the temperature dependence of energy-linked Ca2+ uptake by means of Arrhenius plots reveals two breaks (at around 11°C and 24°C) in mitochondria isolated from selenium-supplemented animals, whereas in selenium-deficient rats the break at 11°C is absent. Ca2+-loaded mitochondria of selenium-supplemented rats—i.e., with active glutathione peroxidase in the matrix—lose Ca2+ rapidly, with a concomitant oxidation of endogenous NAD(P)H, when exposed to t-butyl hydroperoxide or H2O2. In contrast, in selenium deficiency, t-butyl hydroperoxide and H2O2 induce neither a release of Ca2+ nor an oxidation of NAD(P)H. The peroxide-induced oxidation of NAD(P)H is reversible in the presence of succinate when no Ca2+ has been taken up. When Ca2+ has previously been accumulated, however, the oxidation of NAD(P)H is irreversible. Enzymatic analysis of mitochondrial pyridine nucleotides reveals that the peroxide-induced oxidation of NAD(P)H in Ca2+-loaded mitochondria leads to a loss of NAD+ and NADP+. It is proposed that the redox state of mitochondrial pyridine nucleotides can be or is in part controlled by glutathione peroxidase and glutathione reductase and is a factor in the balance of Ca2+ between mitochondria and medium. PMID:41241

  8. Regulation of hypoxia-inducible factor-α isoforms and redox state by carotid body neural activity in rats

    PubMed Central

    Peng, Ying-Jie; Yuan, Guoxiang; Khan, Shakil; Nanduri, Jayasri; Makarenko, Vladislav V; Reddy, Vaddi Damodara; Vasavda, Chirag; Kumar, Ganesh K; Semenza, Gregg L; Prabhakar, Nanduri R

    2014-01-01

    Previous studies reported that chronic intermittent hypoxia (CIH) results in an imbalanced expression of hypoxia-inducible factor-α (HIF-α) isoforms and oxidative stress in rodents, which may be due either to the direct effect of CIH or indirectly via hitherto uncharacterized mechanism(s). As neural activity is a potent regulator of gene transcription, we hypothesized that carotid body (CB) neural activity contributes to CIH-induced HIF-α isoform expression and oxidative stress in the chemoreflex pathway. Experiments were performed on adult rats exposed to CIH for 10 days. Rats exposed to CIH exhibited: increased HIF-1α and decreased HIF-2α expression; increased NADPH oxidase 2 and decreased superoxide dismutase 2 expression; and oxidative stress in the nucleus tractus solitarius and rostral ventrolateral medulla as well as in the adrenal medulla (AM), a major end organ of the sympathetic nervous system. Selective ablation of the CB abolished these effects. In the AM, sympathetic activation by the CB chemoreflex mediates CIH-induced HIF-α isoform imbalance via muscarinic acetylcholine receptor-mediated Ca2+ influx, and the resultant activation of mammalian target of rapamycin pathway and calpain proteases. Rats exposed to CIH presented with hypertension, elevated sympathetic activity and increased circulating catecholamines. Selective ablation of either the CB (afferent pathway) or sympathetic innervation to the AM (efferent pathway) abolished these effects. These observations uncover CB neural activity-dependent regulation of HIF-α isoforms and the redox state by CIH in the central and peripheral nervous systems associated with the chemoreflex. PMID:24973414

  9. The responses of cytochrome redox state and energy metabolism to dehydration support a role for cytoplasmic viscosity in desiccation tolerance

    PubMed

    Leprince; Hoekstra

    1998-12-01

    To characterize the depression of metabolism in anhydrobiotes, the redox state of cytochromes and energy metabolism were studied during dehydration of soaked cowpea (Vigna unguiculata) cotyledons and pollens of Typha latifolia and Impatiens glandulifera. Between water contents (WC) of 1.0 and 0.6 g H2O/g dry weight (g/g), viscosity as measured by electron spin resonance spectroscopy increased from 0.15 to 0.27 poise. This initial water loss was accompanied by a 50% decrease in respiration rates, whereas the adenylate energy charge remained constant at 0.8, and cytochrome c oxidase (COX) remained fully oxidized. From WC of 0.6 to 0.2 g/g, viscosity increased exponentially. The adenylate energy charge declined to 0.4 in seeds and 0.2 in pollen, whereas COX became progressively reduced. At WC of less than 0.2 g/g, COX remained fully reduced, whereas respiration ceased. When dried under N2, COX remained 63% reduced in cotyledons until WC was 0.7 g/g and was fully reduced at 0.2 g/g. During drying under pure O2, the pattern of COX reduction was similar to that of air-dried tissues, although the maximum reduction was 70% in dried tissues. Thus, at WC of less than 0.6 g/g, the reduction of COX probably originates from a decreased O2 availability as a result of the increased viscosity and impeded diffusion. We suggest that viscosity is a valuable parameter to characterize the relation between desiccation and decrease in metabolism. The implications for desiccation tolerance are discussed.

  10. α-Tocopherol administration blocks adaptive changes in cell NADH/NAD+ redox state and mitochondrial function leading to inhibition of gastric mucosa cell proliferation in rats.

    PubMed

    Olguín-Martínez, Marisela; Hernández-Espinosa, Diego R; Hernández-Muñoz, Rolando

    2013-12-01

    In experimentally induced chronic gastritis, a compensatory mucosal cell proliferation occurs with enhanced glucose oxidative metabolism linked to lipoperoxidative events. Therefore, this study was aimed at assessing the participation of cell NAD/NADH redox state and mitochondrial functions during gastric mucosa proliferation and the effects of in vivo α-tocopherol (vitamin E) administration. Glucose oxidation and oxygen consumption were tested in gastric mucosa samples obtained from rats with gastritis and from those also treated with α-tocopherol. Gastric mucosal mitochondria were isolated and structural and functional parameters were determined. Succinate oxidation, ADP phosphorylation, mitochondrial enzyme activities, and membrane lipid composition were measured. In addition, parameters indicative of cellular NAD/NADH redox state, proliferation, apoptosis, and nitric oxide (NO) metabolism were also determined. After ethanol withdrawal, the damaged gastric mucosa increased glucose and oxygen consumption, events associated with a more reduced cytoplasmic NAD/NADH ratio. Enhanced mitochondrial oxidative phosphorylation and increased mitochondrial enzyme activities occurred early, accompanied by recovery of lost mitochondrial protein and lipid composition in the gastric mucosa, events associated with increased NO production. When mitochondrial function and structural events were normalized, apoptosis was initiated as assessed by the mitochondrial Bax/Bcl2 ratio. Treatment with α-tocopherol inhibited cell proliferation and blocked enhanced glucose utilization, mitochondrial substrate oxidation, and changes in redox state, delaying the onset of these adaptive metabolic changes, whereas it inhibited cell proliferation. In conclusion, α-tocopherol could abolish damage-induced "stress" signaling by desynchronizing mitochondrial adaptive responses, including mitochondria biogenesis, and consequently NAD/NADH redox, which seems to regulate gastric mucosal cell

  11. Redox Redone.

    ERIC Educational Resources Information Center

    Petty, John T.

    1996-01-01

    Presents an extension of the change in oxidation number method that is used for balancing skeletal redox reactions in aqueous solutions. Retains most of the simplicity of the change in oxidation number method but provides the additional step-by-step process necessary for the beginner to balance an equation. (JRH)

  12. Thioredoxins, Glutaredoxins, and Peroxiredoxins—Molecular Mechanisms and Health Significance: from Cofactors to Antioxidants to Redox Signaling

    PubMed Central

    Hanschmann, Eva-Maria; Godoy, José Rodrigo; Berndt, Carsten; Hudemann, Christoph

    2013-01-01

    Abstract Thioredoxins (Trxs), glutaredoxins (Grxs), and peroxiredoxins (Prxs) have been characterized as electron donors, guards of the intracellular redox state, and “antioxidants”. Today, these redox catalysts are increasingly recognized for their specific role in redox signaling. The number of publications published on the functions of these proteins continues to increase exponentially. The field is experiencing an exciting transformation, from looking at a general redox homeostasis and the pathological oxidative stress model to realizing redox changes as a part of localized, rapid, specific, and reversible redox-regulated signaling events. This review summarizes the almost 50 years of research on these proteins, focusing primarily on data from vertebrates and mammals. The role of Trx fold proteins in redox signaling is discussed by looking at reaction mechanisms, reversible oxidative post-translational modifications of proteins, and characterized interaction partners. On the basis of this analysis, the specific regulatory functions are exemplified for the cellular processes of apoptosis, proliferation, and iron metabolism. The importance of Trxs, Grxs, and Prxs for human health is addressed in the second part of this review, that is, their potential impact and functions in different cell types, tissues, and various pathological conditions. Antioxid. Redox Signal. 19, 1539–1605. PMID:23397885

  13. An EMPA investigation of the redox state of natural glasses from mantle xenoliths and mantle-derived boninitic magmas.

    NASA Astrophysics Data System (ADS)

    Fialin, Michel; Wagner, Christiane; Ohnenstetter, Daniel

    2010-05-01

    An EMPA investigation of the redox state of natural glasses from mantle xenoliths and mantle-derived boninitic magmas. M. Fialin1*, C. Wagner2, and D. Ohnenstetter3 1 Centre de Microanalyse Camparis, UPMC Univ Paris 06, CNRS-UMR 7094, IPGP, F-75005, Paris, France. * michel.fialin@upmc.fr 2 Lab. "Magmas, Minéraux, Matériaux", UPMC Univ. Paris 06, CNRS-UMR 7193, iSTeP, F-75005, Paris, France. 3 CRPG, CNRS-UPR 2300, BP20, 54501 Vandœuvre-lès-Nancy, France The recent developments of the electron microprobe analytical procedures in our laboratory allow the direct measurement of the glass ferric-ferrous ratios at a scale of a few micrometer. The determination of the oxidation state of iron is based on the measure of the self-absorption induced shift of the emitted Fe L peak [1, 2, 3]. This method is well suited for the study of glassy phases of few tens of squared micrometers disseminated in a mineral matrix. It can be operated on common petrographic thin sections and, thus, it can be easily coupled with conventional chemical analyses by electron probe microanalysis (EPMA). This latter point is essential because the total Fe content of the glass must be precisely measured by EPMA to scale the corresponding Fe-L peak position relative to the calibration curves giving the Fe3+/SFe ratios. The samples studied are spinel lherzolite from the French Massif Central, and low Ca type 1 boninites from dykes cutting serpentinized peridotite at Népoui, New Caledonia. Glass occurs commonly in mantle xenoliths as small (<10 micrometers) patches in reactional rims but its origin remains controversy and has been interpreted in relation to mantle processes or to interactions with the xenolith host magma. We have previously demonstrated that these xenoliths have been metasomatized, and that the glasses are reaction products between mantle phases and migrating melts [3, 4]. The consensus emerging from different studies is that metasomatism is oxidizing relative to both primitive

  14. A steady state redox zone approach for modeling the transport and degradation of xenobiotic organic compounds from a landfill site

    NASA Astrophysics Data System (ADS)

    Lønborg, Michael J.; Engesgaard, Peter; Bjerg, Poul L.; Rosbjerg, Dan

    2006-10-01

    A redox zonation approach is used as a framework for obtaining biodegradation rate constants of xenobiotic compounds in a landfill plume (Grindsted, Denmark). The aquifer is physically heterogeneous in terms of a complex zonation of different geological units close to the landfill and biogeochemically heterogeneous in terms of a specified redox zonation. First-order degradation rates of six organic compounds (benzene, toluene, ethylbenzene, o-xylene, m/ p-xylene, and naphthalene) were calculated in the methanogenic/sulfate- and Fe-reducing zones. The numerical simulations show that all compounds are anaerobically biodegraded, but at very different rates. High rates of biodegradation of most of the compounds (except benzene) were found in the Fe-reducing zone. These rates generally agree with previously published rates. Only o-xylene and toluene were significantly biodegraded in the methanogenic/sulfate-reducing environment. All rates in this redox zone are generally much lower than previously published rates.

  15. Intracellular proteoglycans.

    PubMed Central

    Kolset, Svein Olav; Prydz, Kristian; Pejler, Gunnar

    2004-01-01

    Proteoglycans (PGs) are proteins with glycosaminoglycan chains, are ubiquitously expressed and have a wide range of functions. PGs in the extracellular matrix and on the cell surface have been the subject of extensive structural and functional studies. Less attention has so far been given to PGs located in intracellular compartments, although several reports suggest that these have biological functions in storage granules, the nucleus and other intracellular organelles. The purpose of this review is, therefore, to present some of these studies and to discuss possible functions linked to PGs located in different intracellular compartments. Reference will be made to publications relevant for the topics we present. It is beyond the scope of this review to cover all publications on PGs in intracellular locations. PMID:14759226

  16. In-vitro monitoring of redox state of cytochrome oxidase in bone by optical coherence quantitation based on low-coherence interferometry

    NASA Astrophysics Data System (ADS)

    Xu, Xiangqun; Wang, Ruikang K.; El Haj, Alicia J.

    2001-05-01

    We present optical coherence quantitation technique to monitor the redox state of mitochondria enzyme Cytochrome oxidase (CytOx) in bone tissue by the use of optical coherence tomography (OCT) system. Superluminescent diode (SLD) with its peak emission wavelength ((lambda) = 820nm) on the absorption band of oxidized form of CytOx was used in the experiments. The reflectance returning from the liquid phantoms (naphthol green B with intralipid) and bone tissue specimens (periosteum of calvaria from newborn rats) as a function of penetration depth was used to quantify the absorption changes of the sample. Absorption coefficients of naphthol green B were accurately quantified by the linear relationship between attenuation coefficients from the slopes of the reflected signals and naphthol green B concentration. The results show that the attenuation coefficient decreases in periosteums as CytOx is reduced by sodium dithionite, demonstrating the feasibility of this method to quantify the redox state of tissues studied. A 70% +/- 7% (n=4) reduction of attenuation coefficients in periosteums was clearly observed with redox change of CytOx after 5 min reduction. In addition, the results demonstrate that the OCT system is also capable of imaging the calvaria tomographically with a resolution at 9 microns, which could only be previously obtained by the conventional excisional biopsy.

  17. Changes in the redox state and endogenous fluorescence of in vivo human skin due to intrinsic and photo-aging, measured by multiphoton tomography with fluorescence lifetime imaging.

    PubMed

    Sanchez, Washington Y; Obispo, Clara; Ryan, Elizabeth; Grice, Jeffrey E; Roberts, Michael S

    2013-06-01

    Ultraviolet radiation from solar exposure is a key extrinsic factor responsible for premature skin aging (i.e., photo-aging). Recent advances using in vivo multiphoton tomography (MPT) demonstrate the efficacy of this approach to assess intrinsic and extrinsic skin aging as an alternative to existing invasive techniques. In this study, we measured changes in epidermal autofluorescence, dermal collagen second harmonic generation (SHG), and the redox state of solar-exposed and solar-protected human skin by MPT with fluorescence lifetime imaging (MPT-FLIM). Twenty-four volunteers across four age categories (20 to 29, 30 to 39, 40 to 49, and 50 to 59 years old; six volunteers each) were recruited for MPT-FLIM imaging of the dorsal (solar-exposed; photo-damaged) and volar (solar-protected) forearm. We demonstrate a higher intensity of dermal collagen SHG within the volar forearm compared to dorsal solar-exposed skin. Redox imaging of each epidermal skin stratum by FLIM demonstrates an increase in fluorescence lifetime in the solar-exposed dorsal forearm that is more apparent in aged skin. The results of this study suggest the redox state of the viable epidermis is a key marker in assessing intrinsic and photo-damage skin aging, in combination with changes in autofluorescence and SHG.

  18. Changes in the redox state and endogenous fluorescence of in vivo human skin due to intrinsic and photo-aging, measured by multiphoton tomography with fluorescence lifetime imaging

    NASA Astrophysics Data System (ADS)

    Sanchez, Washington Y.; Obispo, Clara; Ryan, Elizabeth; Grice, Jeffrey E.; Roberts, Michael S.

    2013-06-01

    Ultraviolet radiation from solar exposure is a key extrinsic factor responsible for premature skin aging (i.e., photo-aging). Recent advances using in vivo multiphoton tomography (MPT) demonstrate the efficacy of this approach to assess intrinsic and extrinsic skin aging as an alternative to existing invasive techniques. In this study, we measured changes in epidermal autofluorescence, dermal collagen second harmonic generation (SHG), and the redox state of solar-exposed and solar-protected human skin by MPT with fluorescence lifetime imaging (MPT-FLIM). Twenty-four volunteers across four age categories (20 to 29, 30 to 39, 40 to 49, and 50 to 59 years old; six volunteers each) were recruited for MPT-FLIM imaging of the dorsal (solar-exposed; photo-damaged) and volar (solar-protected) forearm. We demonstrate a higher intensity of dermal collagen SHG within the volar forearm compared to dorsal solar-exposed skin. Redox imaging of each epidermal skin stratum by FLIM demonstrates an increase in fluorescence lifetime in the solar-exposed dorsal forearm that is more apparent in aged skin. The results of this study suggest the redox state of the viable epidermis is a key marker in assessing intrinsic and photo-damage skin aging, in combination with changes in autofluorescence and SHG.

  19. Light-induced short-term adaptation mechanisms under redox control in the PS II-LHCII supercomplex: LHC II state transitions and PS II repair cycle

    NASA Astrophysics Data System (ADS)

    Kruse, Olaf

    2001-05-01

    Oxygenic photosynthesis takes place in the thylakoid membranes of cyanobacteria, algae and higher plants. While cyanobacteria have adapted to relatively constant environments, higher plants had to evolve mechanisms to adapt to continuous environmental changes. These include changes in light intensity, temperature and availability of water. One of the great challenges in plant cell biology is therefore to determine the regulatory mechanisms employed by higher plants and some algae to adapt to these constant environmental changes. The particular emphasis of this review is the description and characterisation of light-induced redox-controlled processes regulating the photosynthetic reactions, which involves maintaining maximal electron transport flow through the PS II-Cytb6f-PS I-FoF1ATPase electron transport chain and minimising light-induced oxidative damage to PS II which drives the highly oxidising water-splitting reaction. Two of the mechanisms involved in such short-term regulation processes are known as light harvesting complex II (LHC II) state transitions and photosystem II (PS II) repair cycle. They are followed by, and indeed may be a precondition in order to establish, the onset of the subsequent long-term mechanisms of regulation. In particular, the redox control of LHC II state transitions by reversible phosphorylation has been in the focus of many investigations, leading to many new results demonstrating the complexity of thylakoid-associated redox control mechanisms.

  20. Arabidopsis dehydroascorbate reductase 1 and 2 modulate redox states of ascorbate-glutathione cycle in the cytosol in response to photooxidative stress.

    PubMed

    Noshi, Masahiro; Yamada, Hiroki; Hatanaka, Risa; Tanabe, Noriaki; Tamoi, Masahiro; Shigeoka, Shigeru

    2017-03-01

    Ascorbate and glutathione are indispensable cellular redox buffers and allow plants to acclimate stressful conditions. Arabidopsis contains three functional dehydroascorbate reductases (DHAR1-3), which catalyzes the conversion of dehydroascorbate into its reduced form using glutathione as a reductant. We herein attempted to elucidate the physiological role in DHAR1 and DHAR2 in stress responses. The total DHAR activities in DHAR knockout Arabidopsis plants, dhar1 and dhar2, were 22 and 92%, respectively, that in wild-type leaves. Under high light (HL), the levels of total ascorbate and dehydroascorbate were only reduced and increased, respectively, in dhar1. The oxidation of glutathione under HL was significantly inhibited in both dhar1 and dhar2, while glutathione contents were only enhanced in dhar1. The dhar1 showed stronger visible symptoms than the dhar2 under photooxidative stress conditions. Our results demonstrated a pivotal role of DHAR1 in the modulation of cellular redox states under photooxidative stress.

  1. Chromium Isotopes in Carbonates - a Tracer for Climate Change and for Reconstructing the Redox state of Ancient Seawater

    NASA Astrophysics Data System (ADS)

    Frei, R.; Gaucher, C.; Dossing, L. N.; Sial, A. N.

    2011-12-01

    the redox state of ancient seawater since positive values indicate that, at least locally, Neoproterozoic shallow ocean waters were sufficiently oxidized to fractionate chromium and/or that oxygen levels of the atmosphere were sufficient to transform Cr(III) into the more mobile hexavalent Cr(VI) formed during weathering processes on land. The fact that 87Sr/86Sr values, despite δ13C fluctuations, remain low (indicative of a strong hydrothermal input into the basin at his time) implies that CO2 limitation was the cause of negative δ13C and δ53Cr excursions in otherwise nutrient rich late Vendian basins, and that glaciation is only one more consequence of a tectonically driven, biologically mediated system. In such a scenario, glaciation acts as an amplifier of δ53Cr signals. These signals in marine carbonates are a sensitive tracer for redox processes in the ocean and/or on land and have the potential to contribute significantly to the reconstruction of climatic changes, particularly those that are associated with major glaciation periods in Earth's history.

  2. Chromium isotopes in carbonates — A tracer for climate change and for reconstructing the redox state of ancient seawater

    NASA Astrophysics Data System (ADS)

    Frei, R.; Gaucher, C.; Døssing, L. N.; Sial, A. N.

    2011-12-01

    powerful tool for reconstructing the redox state of ancient seawater since positive values indicate that, at least locally, Neoproterozoic shallow ocean waters were sufficiently oxidized to fractionate chromium and/or that oxygen levels of the atmosphere were sufficient to transform Cr(III) into the more mobile hexavalent Cr(VI) formed during weathering processes on land. The fact that 87Sr/ 86Sr values, despite δ 13C fluctuations, remain low (indicative of a strong hydrothermal input into the basin at his time) implies that CO 2 limitation was the cause of negative δ 13C and δ 53Cr excursions in otherwise nutrient rich late Neoproterozoic basins, and that glaciation is only one more consequence of a tectonically driven, biologically mediated system. In such a scenario, glaciation acts as an amplifier of δ 53Cr signals. These signals in marine carbonates are a sensitive tracer for redox processes in the ocean and/or on land and have the potential to contribute significantly, in combination with the other commonly used isotopic tracers, to the reconstruction of climatic changes, particularly those that are associated with major glaciation periods in Earth's history.

  3. Melatonin supplementation decreases prolactin synthesis and release in rat adenohypophysis: correlation with anterior pituitary redox state and circadian clock mechanisms.

    PubMed

    Jiménez-Ortega, Vanesa; Barquilla, Pilar Cano; Pagano, Eleonora S; Fernández-Mateos, Pilar; Esquifino, Ana I; Cardinali, Daniel P

    2012-10-01

    In the laboratory rat, a number of physiological parameters display seasonal changes even under constant conditions of temperature, lighting, and food availability. Since there is evidence that prolactin (PRL) is, among the endocrine signals, a major mediator of seasonal adaptations, the authors aimed to examine whether melatonin administration in drinking water resembling in length the exposure to a winter photoperiod could affect accordingly the 24-h pattern of PRL synthesis and release and some of their anterior pituitary redox state and circadian clock modulatory mechanisms. Melatonin (3 µg/mL drinking water) or vehicle was given for 1 mo, and rats were euthanized at six time intervals during a 24-h cycle. High concentrations of melatonin (>2000 pg/mL) were detected in melatonin-treated rats from beginning of scotophase (at 21:00 h) to early photophase (at 09:00 h) as compared with a considerably narrower high-melatonin phase observed in controls. By cosinor analysis, melatonin-treated rats had significantly decreased MESOR (24-h time-series average) values of anterior pituitary PRL gene expression and circulating PRL, with acrophases (peak time) located in the middle of the scotophase, as in the control group. Melatonin treatment disrupted the 24-h pattern of anterior pituitary gene expression of nitric oxide synthase (NOS)-1 and -2, heme oxygenase-1 and -2, glutathione peroxidase, glutathione reductase, Cu/Zn- and Mn-superoxide dismutase, and catalase by shifting their acrophases to early/middle scotophase or amplifying the maxima. Only the inhibitory effect of melatonin on pituitary NOS-2 gene expression correlated temporally with inhibition of PRL production. Gene expression of metallothionein-1 and -3 showed maxima at early/middle photophase after melatonin treatment. The 24-h pattern of anterior pituitary lipid peroxidation did not vary after treatment. In vehicle-treated rats, Clock and Bmal1 expression peaked in the anterior pituitary at middle

  4. Expression, purification, crystallization and X-ray crystallographic studies of different redox states of the active site of thioredoxin 1 from the whiteleg shrimp Litopenaeus vannamei

    PubMed Central

    Campos-Acevedo, Adam A.; Garcia-Orozco, Karina D.; Sotelo-Mundo, Rogerio R.; Rudiño-Piñera, Enrique

    2013-01-01

    Thioredoxin (Trx) is a 12 kDa cellular redox protein that belongs to a family of small redox proteins which undergo reversible oxidation to produce a cystine disulfide bond through the transfer of reducing equivalents from the catalytic site cysteine residues (Cys32 and Cys35) to a disulfide substrate. In this study, crystals of thioredoxin 1 from the Pacific whiteleg shrimp Litopenaeus vannamei (LvTrx) were successfully obtained. One data set was collected from each of four crystals at 100 K and the three-dimensional structures of the catalytic cysteines in different redox states were determined: reduced and oxidized forms at 2.00 Å resolution using data collected at a synchrotron-radiation source and two partially reduced structures at 1.54 and 1.88 Å resolution using data collected using an in-house source. All of the crystals belonged to space group P3212, with unit-cell parameters a = 57.5 (4), b = 57.5 (4), c = 118.1 (8) Å. The asymmetric unit contains two subunits of LvTrx, with a Matthews coefficient (V M) of 2.31 Å3 Da−1 and a solvent content of 46%. Initial phases were determined by molecular replacement using the crystallographic model of Trx from Drosophila melanogaster as a template. In the present work, LvTrx was overexpressed in Escherichia coli, purified and crystallized. Structural analysis of the different redox states at the Trx active site highlights its reactivity and corroborates the existence of a dimer in the crystal. In the crystallographic structures the dimer is stabilized by several interactions, including a disulfide bridge between Cys73 of each LvTrx monomer, a hydrogen bond between the side chain of Asp60 of each monomer and several hydrophobic interactions, with a noncrystallographic twofold axis. PMID:23695560

  5. Expression, purification, crystallization and X-ray crystallographic studies of different redox states of the active site of thioredoxin 1 from the whiteleg shrimp Litopenaeus vannamei.

    PubMed

    Campos-Acevedo, Adam A; Garcia-Orozco, Karina D; Sotelo-Mundo, Rogerio R; Rudiño-Piñera, Enrique

    2013-05-01

    Thioredoxin (Trx) is a 12 kDa cellular redox protein that belongs to a family of small redox proteins which undergo reversible oxidation to produce a cystine disulfide bond through the transfer of reducing equivalents from the catalytic site cysteine residues (Cys32 and Cys35) to a disulfide substrate. In this study, crystals of thioredoxin 1 from the Pacific whiteleg shrimp Litopenaeus vannamei (LvTrx) were successfully obtained. One data set was collected from each of four crystals at 100 K and the three-dimensional structures of the catalytic cysteines in different redox states were determined: reduced and oxidized forms at 2.00 Å resolution using data collected at a synchrotron-radiation source and two partially reduced structures at 1.54 and 1.88 Å resolution using data collected using an in-house source. All of the crystals belonged to space group P3212, with unit-cell parameters a = 57.5 (4), b = 57.5 (4), c = 118.1 (8) Å. The asymmetric unit contains two subunits of LvTrx, with a Matthews coefficient (VM) of 2.31 Å(3) Da(-1) and a solvent content of 46%. Initial phases were determined by molecular replacement using the crystallographic model of Trx from Drosophila melanogaster as a template. In the present work, LvTrx was overexpressed in Escherichia coli, purified and crystallized. Structural analysis of the different redox states at the Trx active site highlights its reactivity and corroborates the existence of a dimer in the crystal. In the crystallographic structures the dimer is stabilized by several interactions, including a disulfide bridge between Cys73 of each LvTrx monomer, a hydrogen bond between the side chain of Asp60 of each monomer and several hydrophobic interactions, with a noncrystallographic twofold axis.

  6. Optical Cryoimaging Reveals a Heterogeneous Distribution of Mitochondrial Redox State in ex vivo Guinea Pig Hearts and Its Alteration During Ischemia and Reperfusion

    PubMed Central

    Motlagh, Mohammad Masoudi; Salehpour, Fahimeh; Sepehr, Reyhaneh; Heisner, James S.; Dash, Ranjan K.; Camara, Amadou K. S.

    2016-01-01

    Oxidation of substrates to generate ATP in mitochondria is mediated by redox reactions of NADH and FADH2. Cardiac ischemia and reperfusion (IR) injury compromises mitochondrial oxidative phosphorylation. We hypothesize that IR alters the metabolic heterogeneity of mitochondrial redox state of the heart that is only evident in the 3-D optical cryoimaging of the perfused heart before, during, and after IR. The study involved four groups of hearts: time control (TC: heart perfusion without IR), global ischemia (Isch), global ischemia followed by reperfusion (IR) and TC with PCP (a mitochondrial uncoupler) perfusion. Mitochondrial NADH and FAD autofluorescence signals were recorded spectrofluorometrically online in guinea pig ex vivo-perfused hearts in the Langendorff mode. At the end of each specified protocol, hearts were rapidly removed and snap frozen in liquid N2 for later 3-D optical cryoimaging of the mitochondrial NADH, FAD, and NADH/FAD redox ratio (RR). The TC hearts revealed a heterogeneous spatial distribution of NADH, FAD, and RR. Ischemia and IR altered the spatial distribution and caused an overall increase and decrease in the RR by 55% and 64%, respectively. Uncoupling with PCP resulted in the lowest level of the RR (73% oxidation) compared with TC. The 3-D optical cryoimaging of the heart provides novel insights into the heterogeneous distribution of mitochondrial NADH, FAD, RR, and metabolism from the base to the apex during ischemia and IR. This 3-D information of the mitochondrial redox state in the normal and ischemic heart was not apparent in the dynamic spectrofluorometric data. PMID:27574574

  7. Kinase inhibitors with redox and anti-inflammatory activities.

    PubMed

    Ivanovska, Nina; Saso, Luciano; Dimitrov, Petya

    2015-01-01

    The development of inflammatory immune response is related to an activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling. The intracellular molecules from this pathway are sensitive to the alterations in the microenvironment. The changes in cellular redox state, proliferation, gene expression pattern and genomic stability during inflammation induce the activation of non-canonical and atypical NK-κB signaling increasing the crosstalk with molecules involved in neddylation, cell cycle checkpoints regulation and DNA repair. This review article describes the reactive oxygen species (ROS)-sensitive kinases from the NF-κB pathway and presents the effects of their suppression by small kinase inhibitors. It illustrates that selective targeting of the redox sensor molecules from the inflammatory NK- κB cascades can influence cell survival and metabolism as well. We think that this issue is important when evaluating the drug efficacy in clinical studies and their side effects.

  8. Absence of Mycobacterium intracellulare and presence of Mycobacterium chimaera in household water and biofilm samples of patients in the United States with Mycobacterium avium complex respiratory disease.

    PubMed

    Wallace, Richard J; Iakhiaeva, Elena; Williams, Myra D; Brown-Elliott, Barbara A; Vasireddy, Sruthi; Vasireddy, Ravikiran; Lande, Leah; Peterson, Donald D; Sawicki, Janet; Kwait, Rebecca; Tichenor, Wellington S; Turenne, Christine; Falkinham, Joseph O

    2013-06-01

    Recent studies have shown that respiratory isolates from pulmonary disease patients and household water/biofilm isolates of Mycobacterium avium could be matched by DNA fingerprinting. To determine if this is true for Mycobacterium intracellulare, household water sources for 36 patients with Mycobacterium avium complex (MAC) lung disease were evaluated. MAC household water isolates from three published studies that included 37 additional MAC respiratory disease patients were also evaluated. Species identification was done initially using nonsequencing methods with confirmation by internal transcribed spacer (ITS) and/or partial 16S rRNA gene sequencing. M. intracellulare was identified by nonsequencing methods in 54 respiratory cultures and 41 household water/biofilm samples. By ITS sequencing, 49 (90.7%) respiratory isolates were M. intracellulare and 4 (7.4%) were Mycobacterium chimaera. In contrast, 30 (73%) household water samples were M. chimaera, 8 (20%) were other MAC X species (i.e., isolates positive with a MAC probe but negative with species-specific M. avium and M. intracellulare probes), and 3 (7%) were M. avium; none were M. intracellulare. In comparison, M. avium was recovered from 141 water/biofilm samples. These results indicate that M. intracellulare lung disease in the United States is acquired from environmental sources other than household water. Nonsequencing methods for identification of nontuberculous mycobacteria (including those of the MAC) might fail to distinguish closely related species (such as M. intracellulare and M. chimaera). This is the first report of M. chimaera recovery from household water. The study underscores the importance of taxonomy and distinguishing the many species and subspecies of the MAC.

  9. Absence of Mycobacterium intracellulare and Presence of Mycobacterium chimaera in Household Water and Biofilm Samples of Patients in the United States with Mycobacterium avium Complex Respiratory Disease

    PubMed Central

    Iakhiaeva, Elena; Williams, Myra D.; Brown-Elliott, Barbara A.; Vasireddy, Sruthi; Vasireddy, Ravikiran; Lande, Leah; Peterson, Donald D.; Sawicki, Janet; Kwait, Rebecca; Tichenor, Wellington S.; Turenne, Christine; Falkinham, Joseph O.

    2013-01-01

    Recent studies have shown that respiratory isolates from pulmonary disease patients and household water/biofilm isolates of Mycobacterium avium could be matched by DNA fingerprinting. To determine if this is true for Mycobacterium intracellulare, household water sources for 36 patients with Mycobacterium avium complex (MAC) lung disease were evaluated. MAC household water isolates from three published studies that included 37 additional MAC respiratory disease patients were also evaluated. Species identification was done initially using nonsequencing methods with confirmation by internal transcribed spacer (ITS) and/or partial 16S rRNA gene sequencing. M. intracellulare was identified by nonsequencing methods in 54 respiratory cultures and 41 household water/biofilm samples. By ITS sequencing, 49 (90.7%) respiratory isolates were M. intracellulare and 4 (7.4%) were Mycobacterium chimaera. In contrast, 30 (73%) household water samples were M. chimaera, 8 (20%) were other MAC X species (i.e., isolates positive with a MAC probe but negative with species-specific M. avium and M. intracellulare probes), and 3 (7%) were M. avium; none were M. intracellulare. In comparison, M. avium was recovered from 141 water/biofilm samples. These results indicate that M. intracellulare lung disease in the United States is acquired from environmental sources other than household water. Nonsequencing methods for identification of nontuberculous mycobacteria (including those of the MAC) might fail to distinguish closely related species (such as M. intracellulare and M. chimaera). This is the first report of M. chimaera recovery from household water. The study underscores the importance of taxonomy and distinguishing the many species and subspecies of the MAC. PMID:23536397

  10. Differential Regulation of the Extracellular Cysteine/Cystine Redox State (EhCySS) by Lung Fibroblasts from Young and Old Mice

    PubMed Central

    Roman, Jesse

    2016-01-01

    Aging is associated with progressive oxidation of plasma cysteine (Cys)/cystine (CySS) redox state, expressed as EhCySS. Cultured cells condition their media to reproduce physiological EhCySS, but it is unknown whether aged cells produce a more oxidized extracellular environment reflective of that seen in vivo. In the current study, we isolated primary lung fibroblasts from young and old female mice and measured the media EhCySS before and after challenge with Cys or CySS. We also measured expression of genes related to redox regulation and fibroblast function. These studies revealed that old fibroblasts produced a more oxidizing extracellular EhCySS than young fibroblasts and that old fibroblasts had a decreased capacity to recover from an oxidative challenge due to a slower rate of reduction of CySS to Cys. These defects were associated with 10-fold lower expression of the Slc7a11 subunit of the xCT cystine-glutamate transporter. Extracellular superoxide dismutase (Sod3) was the only antioxidant or thiol-disulfide regulating enzyme among 36 examined that was downregulated in old fibroblasts by more than 2-fold, but there were numerous changes in extracellular matrix components. Thus, aging fibroblasts not only contribute to remodeling of the extracellular matrix but also have a profound effect on the extracellular redox environment. PMID:27642492

  11. Probing the Redox States of Sodium Channel Cysteines at the Binding Site of μO§-Conotoxin GVIIJ.

    PubMed

    Zhang, Min-Min; Gajewiak, Joanna; Azam, Layla; Bulaj, Grzegorz; Olivera, Baldomero M; Yoshikami, Doju

    2015-06-30

    μO§-Conotoxin GVIIJ is a 35-amino acid peptide that readily blocks six of eight tested NaV1 subunit isoforms of voltage-gated sodium channels. μO§-GVIIJ is unusual in having an S-cysteinylated cysteine (at residue 24). A proposed reaction scheme involves the peptide-channel complex stabilized by a disulfide bond formed via thiol-disulfide exchange between Cys24 of the peptide and a Cys residue at neurotoxin receptor site 8 in the pore module of the channel (specifically, Cys910 of rat NaV1.2). To examine this model, we synthesized seven derivatives of μO§-GVIIJ in which Cys24 was disulfide-bonded to various thiols (or SR groups) and tested them on voltage-clamped Xenopus laevis oocytes expressing NaV1.2. In the proposed model, the SR moiety is a leaving group that is no longer present in the final peptide-channel complex; thus, the same koff value should be obtained regardless of the SR group. We observed that all seven derivatives, whose kon values varied over a 30-fold range, had the same koff value. Concordant results were observed with NaV1.6, for which the koff was 17-fold larger. Additionally, we tested two μO§-GVIIJ derivatives (where SR was glutathione or a free thiol) on two NaV1.2 Cys replacement mutants (NaV1.2[C912A] and NaV1.2[C918A]) without and with reduction of channel disulfides by dithiothreitol. The results indicate that Cys910 in wild-type NaV1.2 has a free thiol and conversely suggest that in NaV1.2[C912A] and NaV1.2[C918A], Cys910 is disulfide-bonded to Cys918 and Cys912, respectively. Redox states of extracellular cysteines of sodium channels have hitherto received scant attention, and further experiments with GVIIJ may help fill this void.

  12. Intrinsic oxygen fugacity measurements on seven chondrites, a pallasite, and a tektite and the redox state of meteorite parent bodies

    USGS Publications Warehouse

    Brett, R.; Sato, M.

    1984-01-01

    Intrinsic oxygen-fugacity (fO2) measurements were made on five ordinary chondrites, a carbonaceous chondrite, an enstatite chondrite, a pallasite, and a tektite. Results are of the form of linear log fO2 - 1 T plots. Except for the enstatite chondrite, measured results agree well with calculated estimates by others. The tektite produced fO2 values well below the range measured for terrestrial and lunar rocks. The lowpressure atmospheric regime that is reported to follow large terrestrial explosions, coupled with a very high temperature, could produce glass with fO2 in the range measured. The meteorite Salta (pallasite) has low fO2 and lies close to Hvittis (E6). Unlike the other samples, results for Salta do not parallel the iron-wu??stite buffer, but are close to the fayalite-quartz-iron buffer in slope. Minor reduction by graphite appears to have taken place during metamorphism of ordinary chondrites. fO2 values of unequilibrated chondrites show large scatter during early heating suggesting that the constituent phases were exposed to a range of fO2 conditions. The samples equilibrated with respect to fO2 in relatively short time on heating. Equilibration with respect to fO2 in ordinary chondrites takes place between grades 3 and 4 of metamorphism. Application of P - T - fO2 relations in the system C-CO-CO2 indicates that the ordinary chondrites were metamorphosed at pressures of 3-20 bars, as it appears that they lay on the graphite surface. A steep positive thermal gradient in a meteorite parent body lying at the graphite surface will produce thin reduced exterior, an oxidized near-surface layer, and an interior that is increasingly reduced with depth; a shallow thermal gradient will produce the reverse. A body heated by accretion on the outside will have a reduced exterior and oxidized interior. Meteorites from the same parent body clearly are not required to have similar redox states. ?? 1984.

  13. Solid-state thermolysis of a fac-rhenium(I) carbonyl complex with a redox non-innocent pincer ligand.

    PubMed

    Jurca, Titel; Chen, Wen-Ching; Michel, Sheila; Korobkov, Ilia; Ong, Tiow-Gan; Richeson, Darrin S

    2013-03-25

    The development of rhenium(I) chemistry has been restricted by the limited structural and electronic variability of the common pseudo-octahedral products fac-[ReX(CO)3L2] (L2 = α-diimine). We address this constraint by first preparing the bidentate bis(imino)pyridine complexes [(2,6-{2,6-Me2C6H3N=CPh}2C5H3N)Re(CO)3X] (X = Cl 2, Br 3), which were characterized by spectroscopic and X-ray crystallographic means, and then converting these species into tridentate pincer ligand compounds, [(2,6-{2,6-Me2C6H3N=CPh}2C5H3N)Re(CO)2X] (X = Cl 4, Br 5). This transformation was performed in the solid-state by controlled heating of 2 or 3 above 200 °C in a tube furnace under a flow of nitrogen gas, giving excellent yields (≥95 %). Compounds 4 and 5 define a new coordination environment for rhenium(I) carbonyl chemistry where the metal center is supported by a planar, tridentate pincer-coordinated bis(imino)pyridine ligand. The basic photophysical features of these compounds show significant elaboration in both number and intensity of the d-π* transitions observed in the UV/Vis spec tra relative to the bidentate starting materials, and these spectra were analyzed using time-dependent DFT computations. The redox nature of the bis(imino)pyridine ligand in compounds 2 and 4 was examined by electrochemical analysis, which showed two ligand reduction events and demonstrated that the ligand reduction shifts to a more positive potential when going from bidentate 2 to tridentate 4 (+160 mV for the first reduction step and +90 mV for the second). These observations indicate an increase in electrostatic stabilization of the reduced ligand in the tridentate conformation. Elaboration on this synthetic methodology documented its generality through the preparation of the pseudo-octahedral rhenium(I) triflate complex [(2,6-{2,6-Me2C6H3N=CPh}2C5H3N)Re(CO)2OTf] (7, 93 % yield). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Rapid loss of adiponectin-stimulated fatty acid oxidation in skeletal muscle of rats fed a high fat diet is not due to altered muscle redox state.

    PubMed

    Ritchie, Ian R W; Dyck, David J

    2012-01-01

    A high fat (HF) diet rapidly impairs the ability of adiponectin (Ad) to stimulate fatty acid (FA) oxidation in oxidative soleus muscle, but the underlying mechanism remains elusive. Mere days of HF feeding also increase the muscle's production and accumulation of reactive oxygen species (ROS) and shift cellular redox to a more oxidized state. It seems plausible that this shift towards a more oxidized state might act as negative feedback to suppress the ability of Ad to stimulate FA oxidation and generate more ROS. Therefore, we sought to determine whether i) a shift towards a more oxidized redox state (reduction in GSH/2GSSG) coincided with impaired Ad-stimulated palmitate oxidation in oxidative and glycolytic rodent muscle after 5 days of HF feeding (60% kCal), and ii) if supplementation with the antioxidant, N-acetylcysteine (NAC) could prevent the HF-diet induced impairment in Ad-response. Globular Ad (gAd) increased palmitate oxidation in isolated soleus and EDL muscles by 42% and 34%, respectively (p<0.05) but this was attenuated with HF feeding in both muscles. HF feeding decreased total GSH (-26%, p<0.05) and GSH/2GSSG (-49%, p<0.05) in soleus, but not EDL. Supplementation with NAC prevented the HF diet-induced reductions in GSH and GSH/2GSSG in soleus, but did not prevent the loss of Ad response in either muscle. Furthermore, direct incubations with H(2)O(2) did not impair Ad-stimulated FA oxidation in either muscle. In conclusion, our data indicates that skeletal muscle Ad resistance is rapidly induced in both oxidative and glycolytic muscle, independently of altered cellular redox state.

  15. Diet supplementation for 5 weeks with polyphenol-rich cereals improves several functions and the redox state of mouse leucocytes

    PubMed Central

    Álvarez, Pedro; Alvarado, Carmen; Mathieu, Florence; Jiménez, Liliana

    2006-01-01

    Background Cereals naturally contain a great variety of polyphenols, which exert a wide range of physiological effects both in vitro and in vivo. Many of their protective effects, including an improvement of the function and redox state of immune cells in unhealthy or aged subjects come from their properties as powerful antioxidant compounds. However, whether cereal-based dietary supplementation positively affects the immune function and cellular redox state of healthy subjects remains unclear. Aim of the study To investigate the effects of supplementation (20% wt/wt) for 5 weeks with four different cereal fractions on healthy mice. Methods Several parameters of function and redox state of peritoneal leukocytes were measured. The cereals, named B (wheat germ), C (buckwheat flour), D (fine rice bran) and E (wheat middlings) contained different amounts of gallic acid, p-hydroxybenzoic acid, vanillic acid, sinapic acid, p-coumaric acid, ferulic acid, quercetin, catechin, rutin and oryzanol as major polyphenols. Results In general, all cereal fractions caused an improvement of the leukocyte parameters studied such as chemotaxis capacity, microbicidal activity, lymphoproliferative response to mitogens, interleukin-2 (IL-2) and tumor necrosis factor (TNFα) release, as well as oxidized glutathione (GSSG), GSSG/GSH ratio, catalase (CAT) activity and lipid oxidative damage. We observed similar effects among the cereal fractions. Conclusions The results suggest that some of these effects may due, at least partially, to the antioxidant activity of the polyphenols naturally present in cereals. Since an appropriate function of the leukocytes has been proposed as marker of the health state, a short-term intake of cereals seems to be sufficient to exert a benefit in the health of the general population. However, further studies are needed to assess the optimal doses and to find out which active polyphenols are able to mediate the observed physiological effects before

  16. Redox signaling in cardiovascular health and disease

    PubMed Central

    Madamanchi, Nageswara R.; Runge, Marschall S.

    2013-01-01

    Spatiotemporal regulation of the activity of a vast array of intracellular proteins and signaling pathways by reactive oxygen species (ROS) governs normal cardiovascular function. However, data from experimental and animal studies strongly support that dysregulated redox signaling, resulting from hyper-activation of various cellular oxidases or mitochondrial dysfunction, is integral to the pathogenesis and progression of cardiovascular disease (CVD). In this review, we address how redox signaling modulates the protein function, the various sources of increased oxidative stress in CVD, and the labyrinth of redox-sensitive molecular mechanisms involved in the development of atherosclerosis, hypertension, cardiac hypertrophy and heart failure, and ischemia–reperfusion injury. Advances in redox biology and pharmacology for inhibiting ROS production in specific cell types and subcellular organelles combined with the development of nanotechnology-based new in vivo imaging systems and targeted drug delivery mechanisms may enable fine-tuning of redox signaling for the treatment and prevention of CVD. PMID:23583330

  17. Green fluorescent protein-based monitoring of endoplasmic reticulum redox poise

    PubMed Central

    Birk, Julia; Ramming, Thomas; Odermatt, Alex; Appenzeller-Herzog, Christian

    2013-01-01

    Pathological endoplasmic reticulum (ER) stress is tightly linked to the accumulation of reactive oxidants, which can be both upstream and downstream of ER stress. Accordingly, detrimental intracellular stress signals are amplified through establishment of a vicious cycle. An increasing number of human diseases are characterized by tissue atrophy in response to ER stress and oxidative injury. Experimental monitoring of stress-induced, time-resolved changes in ER reduction-oxidation (redox) states is therefore important. Organelle-specific examination of redox changes has been facilitated by the advent of genetically encoded, fluorescent probes, which can be targeted to different subcellular locations by means of specific amino acid extensions. These probes include redox-sensitive green fluorescent proteins (roGFPs) and the yellow fluorescent protein-based redox biosensor HyPer. In the case of roGFPs, variants with known specificity toward defined redox couples are now available. Here, we review the experimental framework to measure ER redox changes using ER-targeted fluorescent biosensors. Advantages and drawbacks of plate-reader and microscopy-based measurements are discussed, and the power of these techniques demonstrated in the context of selected cell culture models for ER stress. PMID:23781233

  18. Redox regulation by Keap1 and Nrf2 controls intestinal stem cell proliferation in Drosophila

    PubMed Central

    Hochmuth, Christine E.; Biteau, Benoit; Bohmann, Dirk; Jasper, Heinrich

    2010-01-01

    In Drosophila, intestinal stem cells (ISCs) respond to oxidative challenges and inflammation by increasing proliferation rates. This phenotype is part of a regenerative response, but can lead to hyperproliferation and epithelial degeneration in the aging animal. Here we show that Nrf2, a master regulator of the cellular redox state, specifically controls the proliferative activity of ISCs, promoting intestinal homeostasis. We find that Nrf2 is constitutively active in ISCs, and that repression of Nrf2 by its negative regulator Keap1 is required for ISC proliferation. We further show that Nrf2 and Keap1 exert this function in ISCs by regulating the intracellular redox balance. Accordingly, loss of Nrf2 in ISCs causes accumulation of reactive oxygen species and accelerates age-related degeneration of the intestinal epithelium. Our findings establish Keap1 and Nrf2 as a critical redox management system that regulates stem cell function in high-turnover tissues. PMID:21295275

  19. Effect of extracorporeal liver support by molecular adsorbents recirculating system and Prometheus on redox state of albumin in acute-on-chronic liver failure.

    PubMed

    Oettl, Karl; Stadlbauer, Vanessa; Krisper, Peter; Stauber, Rudolf E

    2009-10-01

    Oxidative stress is believed to play an important role in acute-on-chronic liver failure (AoCLF). Albumin, an important transport vehicle, was found to be severely oxidized in AoCLF patients. Extracorporeal liver support systems may exert beneficial effects in AoCLF via removal of albumin-bound toxins. At present, two systems are commercially available, the molecular adsorbents recirculating system (MARS) and fractionated plasma separation, adsorption and dialysis (FPAD, also known as Prometheus). The aim of this study was to compare the effect of MARS and Prometheus treatments on the redox state of human serum albumin. Eight patients with AoCLF underwent alternating treatments with either MARS or Prometheus in a randomized cross-over design. Sixteen treatments (eight MARS and eight Prometheus) were available for analysis. The fraction of human mercaptalbumin (HMA), human nonmercaptalbumin-1 (HNA1), and human nonmercaptalbumin-2 (HNA2) were measured before and after single MARS and Prometheus treatments and during follow-up. In AoCLF patients the oxidized fractions of albumin, HNA1, and HNA2 were markedly increased. Both MARS and Prometheus treatments resulted in a shift of HNA1 to HMA, while HNA2 was not significantly affected. This shift in albumin fractions was transient and disappeared within 24 h after treatment. There were no significant differences between MARS and Prometheus treatments with respect to the redox state of albumin. Both MARS and Prometheus treatments lead to transient improvements of the redox state of albumin, which could be beneficial in the treatment of AoCLF.

  20. Ascorbate oxidase-dependent changes in the redox state of the apoplast modulate gene transcript accumulation leading to modified hormone signaling and orchestration of defense processes in tobacco.

    PubMed

    Pignocchi, Cristina; Kiddle, Guy; Hernández, Iker; Foster, Simon J; Asensi, Amparo; Taybi, Tahar; Barnes, Jeremy; Foyer, Christine H

    2006-06-01

    The role of the redox state of the apoplast in hormone responses, signaling cascades, and gene expression was studied in transgenic tobacco (Nicotiana tabacum) plants with modified cell wall-localized ascorbate oxidase (AO). High AO activity specifically decreased the ascorbic acid (AA) content of the apoplast and altered plant growth responses triggered by hormones. Auxin stimulated shoot growth only when the apoplastic AA pool was reduced in wild-type or AO antisense lines. Oxidation of apoplastic AA in AO sense lines was associated with loss of the auxin response, higher mitogen-activated protein kinase activities, and susceptibility to a virulent strain of the pathogen Pseudomonas syringae. The total leaf glutathione pool, the ratio of reduced glutathione to glutathione disulfide, and glutathione reductase activities were similar in the leaves of all lines. However, AO sense leaves exhibited significantly lower dehydroascorbate reductase and ascorbate peroxidase activities than wild-type and antisense leaves. The abundance of mRNAs encoding antioxidant enzymes was similar in all lines. However, the day/night rhythms in the abundance of transcripts encoding the three catalase isoforms were changed in response to the AA content of the apoplast. Other transcripts influenced by AO included photorespiratory genes and a plasma membrane Ca(2+) channel-associated gene. We conclude that the redox state of the apoplast modulates plant growth and defense responses by regulating signal transduction cascades and gene expression patterns. Hence, AO activity, which modulates the redox state of the apoplastic AA pool, strongly influences the responses of plant cells to external and internal stimuli.

  1. Over-expression of ascorbate oxidase in the apoplast of transgenic tobacco results in altered ascorbate and glutathione redox states and increased sensitivity to ozone.

    PubMed

    Sanmartin, Maite; Drogoudi, Pavlina A M D; Lyons, Tom; Pateraki, Irene; Barnes, Jeremy; Kanellis, Angelos K

    2003-04-01

    Transgenic tobacco ( Nicotiana tabacum L. cv. Xanthi) plants expressing cucumber ascorbate oxidase (EC.1.10.3.3) were used to examine the role of extracellular ascorbic acid in mediating tolerance to the ubiquitous air pollutant, ozone (O(3)). Three homozygous transgenic lines, chosen on the basis of a preliminary screen of AO activity in the leaves of 29 lines, revealed up to a 380-fold increase in AO activity, with expression predominantly associated with leaf cell walls. Over-expression of AO resulted in no change in the total ascorbate content recovered in apoplast washing fluid, but the redox state of ascorbate was reduced from 30% in wild-type leaves to below the threshold for detection in transgenic plants. Levels of ascorbic acid and glutathione in the symplast were not affected by AO over-expression, but the redox state of ascorbate was reduced, while that of glutathione was increased. AO over-expressing plants exposed to 100 nmol mol(-1) ozone for 7 h day(-1) exhibited a substantial increase in foliar injury, and a greater pollutant-induced reduction in both the light-saturated rate of CO(2) assimilation and the maximum in vivo rate of ribulose-1,5-bisphosphate carboxylase/oxygenase carboxylation, compared with wild-type plants. Transgenic plants also exhibited a greater decline in CO(2) assimilation rate when exposed to a brief ozone episode (300 nmol mol(-1) for 8 h). Stomatal conductance, hence O(3) uptake, was unaffected by AO over-expression. Our findings illustrate the important role played by ascorbate redox state and sub-cellular compartmentation in mediating the tolerance of plants to ozone-induced oxidative stress.

  2. Enhanced Hypothalamic Glucose Sensing in Obesity: Alteration of Redox Signaling

    PubMed Central

    Colombani, Anne-Laure; Carneiro, Lionel; Benani, Alexandre; Galinier, Anne; Jaillard, Tristan; Duparc, Thibaut; Offer, Géraldine; Lorsignol, Anne; Magnan, Christophe; Casteilla, Louis; Pénicaud, Luc; Leloup, Corinne

    2009-01-01

    OBJECTIVE Recent data demonstrated that glucose sensing in different tissues is initiated by an intracellular redox signaling pathway in physiological conditions. However, the relevance of such a mechanism in metabolic disease is not known. The aim of the present study was to determine whether brain glucose hypersensitivity present in obese Zücker rats is related to an alteration in redox signaling. RESEARCH DESIGN AND METHODS Brain glucose sensing alteration was investigated in vivo through the evaluation of electrical activity in arcuate nucleus, changes in reactive oxygen species levels, and hypothalamic glucose-induced insulin secretion. In basal conditions, modifications of redox state and mitochondrial functions were assessed through oxidized glutathione, glutathione peroxidase, manganese superoxide dismutase, aconitase activities, and mitochondrial respiration. RESULTS Hypothalamic hypersensitivity to glucose was characterized by enhanced electrical activity of the arcuate nucleus and increased insulin secretion at a low glucose concentration, which does not produce such an effect in normal rats. It was associated with 1) increased reactive oxygen species levels in response to this low glucose load, 2) constitutive oxidized environment coupled with lower antioxidant enzyme activity at both the cellular and mitochondrial level, and 3) overexpression of several mitochondrial subunits of the respiratory chain coupled with a global dysfunction in mitochondrial activity. Moreover, pharmacological restoration of the glutathione hypothalamic redox state by reduced glutathione infusion in the third ventricle fully reversed the cerebral hypersensitivity to glucose. CONCLUSIONS The data demonstrated that obese Zücker rats' impaired hypothalamic regulation in terms of glucose sensing is linked to an abnormal redox signaling, which originates from mitochondria dysfunction. PMID:19581415

  3. [Intermediate states formed during discharge separation in the reaction centers of Rhodospirillum rubrum in the presence of a low-redox potential].

    PubMed

    Godik, V I; Samuilov, V D; Borisov, A Iu

    1978-01-01

    The intermediate short-lived states arising in reaction centre preparations (RC) of purple bacterium Rhodospirillum rubrum are investigated under the conditions of low redox potential. Excitation by 353 and 530 nm laser pulses produced two states characterized by optical absorption changes in the range of 350--650 nm and lifetimes: 10--30 ns for the first state and 2.5 +/- 0.5 microseconds for the second one. The first state is similar to the state PF, described previously by Parson et al. for RC from Rps. sphaeroides. Carotenoid extraction with isooctane resulted in changing the spectrum with tau = 2.5 microseconds and in the appearance of new absorption changes similar to those for the R state observed before in carotenoidless bacterial strains within microsecond time range. The comparison of the microsecond spectra with difference spectra (continuous light minus dark) of RC from R. rubrum in the range of 350--650 nm made it possible to identify the states with tau = 2.5 microseconds as carotenoid triplet states. The ratio of quantum yields of PR and carotenoid triplet states production was determined as being 1 : 1. The conclusion was made that triplet-triplet energy transfer from state PR to carotenoid is responsible for the production of carotenoid triplet states.

  4. Royal jelly may improve the metabolism of glucose and redox state of ovine oocytes matured in vitro and embryonic development following in vitro fertilization.

    PubMed

    Eshtiyaghi, Mahbobeh; Deldar, Hamid; Pirsaraei, Zarbakht Ansari; Shohreh, Bahram

    2016-12-01

    The aim of this study was to investigate the effect of different concentrations of royal jelly (RJ) on in vitro maturation (IVM), fertilization, cleavage, blastocyst rates, glutathione (GSH) content in ovine oocyte, mRNA abundance of antioxidant enzymes in both oocyte and cumulus, and glucose metabolism-related genes in cumulus cells. In vitro maturation of oocyte was performed in the presence of control (RJ0), 2.5 (RJ2.5), 5 (RJ5), and 10 (RJ10) mg/mL of RJ. Nuclear status, intracellular GSH content in oocytes, and mRNA abundance of selected genes were evaluated following 24 hours of IVM. Following the IVM, fertilization and embryo culture were carried out in all the groups and embryonic development was examined. The addition of 10-mg/mL RJ to maturation media not only yielded a higher number of oocytes at MII stage but also showed an increased level of intracellular GSH content than did RJ2.5 and control groups. Fertilization, cleavage, and blastocyst rate were higher in the RJ10 treatment group in comparison to the control one. In cumulus cells, the expression of PFKM, PFKL, and G6PDH were increased following the addition of RJ to the maturation media. Supplementation of 10-mg/mL RJ to IVM medium increased the GPx mRNA abundance in both oocyte and cumulus cells and SOD expression in the cumulus cells. The CAT mRNA abundance was not influenced by the addition of RJ to the maturation media in either oocyte or cumulus cells. It seems that the improvement of oocyte maturation and its subsequent development in RJ10 group may be associated with amelioration of redox status in the oocytes and activation of glucose metabolic pathways in their surrounding cumulus cells.

  5. Oxygen Evolution Reaction Dynamics, Faradaic Charge Efficiency, and the Active Metal Redox States of Ni-Fe Oxide Water Splitting Electrocatalysts.

    PubMed

    Görlin, Mikaela; Chernev, Petko; Ferreira de Araújo, Jorge; Reier, Tobias; Dresp, Sören; Paul, Benjamin; Krähnert, Ralph; Dau, Holger; Strasser, Peter

    2016-05-04

    Mixed Ni-Fe oxides are attractive anode catalysts for efficient water splitting in solar fuels reactors. Because of conflicting past reports, the catalytically active metal redox state of the catalyst has remained under debate. Here, we report an in operando quantitative deconvolution of the charge injected into the nanostructured Ni-Fe oxyhydroxide OER catalysts or into reaction product molecules. To achieve this, we explore the oxygen evolution reaction dynamics and the individual faradaic charge efficiencies using operando differential electrochemical mass spectrometry (DEMS). We further use X-ray absorption spectroscopy (XAS) under OER conditions at the Ni and Fe K-edges of the electrocatalysts to evaluate oxidation states and local atomic structure motifs. DEMS and XAS data consistently reveal that up to 75% of the Ni centers increase their oxidation state from +2 to +3, while up to 25% arrive in the +4 state for the NiOOH catalyst under OER catalysis. The Fe centers consistently remain in the +3 state, regardless of potential and composition. For mixed Ni100-xFex catalysts, where x exceeds 9 atomic %, the faradaic efficiency of O2 sharply increases from ∼30% to 90%, suggesting that Ni atoms largely remain in the oxidation state +2 under catalytic conditions. To reconcile the apparent low level of oxidized Ni in mixed Ni-Fe catalysts, we hypothesize that a kinetic competition between the (i) metal oxidation process and the (ii) metal reduction step during O2 release may account for an insignificant accumulation of detectable high-valent metal states if the reaction rate of process (ii) outweighs that of (i). We conclude that a discussion of the superior catalytic OER activity of Ni-FeOOH electrocatalysts in terms of surface catalysis and redox-inactive metal sites likely represents an oversimplification that fails to capture essential aspects of the synergisms at highly active Ni-Fe sites.

  6. Intracellular ROS

    PubMed Central

    Leshem, Yehoram

    2007-01-01

    Intracellular localization of stress induced reactive oxygen species (ROS) has emerged as an important aspect towards understanding of cellular responses to environmental stimuli. Our recent study published in the PNAS (103:18008–13)1 shows that NaCl-induced ROS appear within endosomes on the way to tonoplast as part of the vacuolar vesicle trafficking. In addition to showing ROS damage to the tonoplast, this finding may shed light upon recently reported aspects of root water relations during salt stress, suggesting a new signaling role for intracellular ROS in Arabidopsis root cells, during salt stress: ROS that are compartmentalized in endosomes are delivered by the vacuolar vesicle trafficking pathway to the tonoplast, resulting in oxidative gating of TIPs water channels. The closure of the tonoplast aquaporins contributes to the observed reduction in root hydraulic conductivity during salt stress. PMID:19704741

  7. Non-equilibrium thermodynamics of thiol/disulfide redox systems: A perspective on redox systems biology

    PubMed Central

    Kemp, Melissa; Go, Young-Mi; Jones, Dean P.

    2008-01-01

    Understanding the dynamics of redox elements in biologic systems remains a major challenge for redox signaling and oxidative stress research. Central redox elements include evolutionarily conserved subsets of cysteines and methionines of proteins which function as sulfur switches and labile reactive oxygen species (ROS) and reactive nitrogen species (RNS) which function in redox signaling. The sulfur switches depend upon redox environments in which rates of oxidation are balanced with rates of reduction through the thioredoxins, glutathione/glutathione disulfide and cysteine/cystine redox couples. These central couples, which we term redox control nodes, are maintained at stable but non-equilibrium steady states, are largely independently regulated in different subcellular compartments and are quasi-independent from each other within compartments. Disruption of the redox control nodes can differentially affect sulfur switches, thereby creating a diversity of oxidative stress responses. Systems biology provides approaches to address the complexity of these responses. In the present review, we summarize thiol/disulfide pathway, redox potential and rate information as a basis for kinetic modeling of sulfur switches. The summary identifies gaps in knowledge especially related to redox communication between compartments, definition of redox pathways and discrimination between types of sulfur switches. A formulation for kinetic modeling of GSH/GSSG redox control indicates that systems biology could encourage novel therapeutic approaches to protect against oxidative stress by identifying specific redox-sensitive sites which could be targeted for intervention. PMID:18155672

  8. Cephalosporin-induced alteration in hepatic glutathione redox state. A potential mechanism for inhibition of hepatic reduction of vitamin K1,2,3-epoxide in the rat.

    PubMed Central

    Mitchell, M C; Mallat, A; Lipsky, J J

    1990-01-01

    Hypoprothrombinemia is a serious adverse effect of antimicrobial therapy that occurs after administration of some second- and third-generation cephalosporins which contain the methyltetrazole-thiol (MTT) group. Previous studies have shown that in vitro MTT directly inhibits microsomal gamma-carboxylation of a synthetic pentapeptide. Since MTT is a thiocarbamide, a type of compound that can increase oxidation of glutathione, the present studies were carried out to determine whether alterations in hepatic glutathione redox state might interfere with vitamin K metabolism. Dose-related increases in biliary efflux and hepatic concentration of oxidized glutathione (GSSG) occurred after intravenous administration of MTT or MTT-containing antibiotics to rats. This finding suggested that these compounds could alter the hepatic glutathione redox state in vivo. Microsomal reduction of vitamin K epoxide occurred in the presence of 100 microM dithiothreitol (DTT), but was inhibited by preincubation with GSSG at concentrations as low as 10 microM. At higher concentrations of DTT (1.0 mM) inhibition by GSSG persisted, but higher concentrations were required, suggesting that the thiol/disulfide ratio, rather than the absolute concentration of GSSG was important. By contrast, GSSG did not effect microsomal gamma-carboxylation of a pentapeptide, using either vitamin K1 or its hydroquinone as a cofactor. These findings suggest a novel mechanism for the hypoprothrombinemia occurring after administration of MTT-containing antibiotics. PMID:1978724

  9. Bacterial Energy Sensor Aer Modulates the Activity of the Chemotaxis Kinase CheA Based on the Redox State of the Flavin Cofactor.

    PubMed

    Samanta, Dipanjan; Widom, Joanne; Borbat, Peter P; Freed, Jack H; Crane, Brian R

    2016-12-09

    Flagellated bacteria modulate their swimming behavior in response to environmental cues through the CheA/CheY signaling pathway. In addition to responding to external chemicals, bacteria also monitor internal conditions that reflect the availability of oxygen, light, and reducing equivalents, in a process termed "energy taxis." In Escherichia coli, the transmembrane receptor Aer is the primary energy sensor for motility. Genetic and physiological data suggest that Aer monitors the electron transport chain through the redox state of its FAD cofactor. However, direct biochemical data correlating FAD redox chemistry with CheA kinase activity have been lacking. Here, we test this hypothesis via functional reconstitution of Aer into nanodiscs. As purified, Aer contains fully oxidized FAD, which can be chemically reduced to the anionic semiquinone (ASQ). Oxidized Aer activates CheA, whereas ASQ Aer reversibly inhibits CheA. Under these conditions, Aer cannot be further reduced to the hydroquinone, in contrast to the proposed Aer signaling model. Pulse ESR spectroscopy of the ASQ corroborates a potential mechanism for signaling in that the resulting distance between the two flavin-binding PAS (Per-Arnt-Sim) domains implies that they tightly sandwich the signal-transducing HAMP domain in the kinase-off state. Aer appears to follow oligomerization patterns observed for related chemoreceptors, as higher loading of Aer dimers into nanodiscs increases kinase activity. These results provide a new methodological platform to study Aer function along with new mechanistic details into its signal transduction process.

  10. Dual Cation- and Anion-Based Redox Process in Lithium Titanium Oxysulfide Thin Film Cathodes for All-Solid-State Lithium-Ion Batteries.

    PubMed

    Dubois, Vincent; Pecquenard, Brigitte; Soulé, Samantha; Martinez, Hervé; Le Cras, Frédéric

    2017-01-25

    A dual redox process involving Ti(3+)/Ti(4+) cation species and S(2-)/(S2)(2-) anion species is highlighted in oxygenated lithium titanium sulfide thin film electrodes during lithium (de)insertion, leading to a high specific capacity. These cathodes for all-solid-state lithium-ion microbatteries are synthesized by sputtering of LiTiS2 targets prepared by different means. The limited oxygenation of the films that is induced during the sputtering process favors the occurrence of the S(2-)/(S2)(2-) redox process at the expense of the Ti(3+)/Ti(4+) one during the battery operation, and influences its voltage profile. Finally, a perfect reversibility of both electrochemical processes is observed, whatever the initial film composition. All-solid-state lithium microbatteries using these amorphous lithiated titanium disulfide thin films and operated between 1.5 and 3.0 V/Li(+)/Li deliver a greater capacity (210-270 mAh g(-1)) than LiCoO2, with a perfect capacity retention (-0.0015% cycle(-1)).

  11. Oxidized ATM promotes abnormal proliferation of breast CAFs through maintaining intracellular redox homeostasis and activating the PI3K-AKT, MEK-ERK, and Wnt-β-catenin signaling pathways.

    PubMed

    Tang, Shifu; Hou, Yixuan; Zhang, Hailong; Tu, Gang; Yang, Li; Sun, Yifan; Lang, Lei; Tang, Xi; Du, Yan-E; Zhou, Mingli; Yu, Tenghua; Xu, Liyun; Wen, Siyang; Liu, Chunming; Liu, Manran

    2015-01-01

    Abnormal proliferation is one characteristic of cancer-associated fibroblasts (CAFs), which play a key role in tumorigenesis and tumor progression. Oxidative stress (OS) is the root cause of CAFs abnormal proliferation. ATM (ataxia-telangiectasia mutated protein kinase), an important redox sensor, is involved in DNA damage response and cellular homeostasis. Whether and how oxidized ATM regulating CAFs proliferation remains unclear. In this study, we show that there is a high level of oxidized ATM in breast CAFs in the absence of double-strand breaks (DSBs) and that oxidized ATM plays a critical role in CAFs proliferation. The effect of oxidized ATM on CAFs proliferation is mediated by its regulation of cellular redox balance and the activity of the ERK, PI3K-AKT, and Wnt signaling pathways. Treating cells with antioxidant N-acetyl-cysteine (NAC) partially rescues the proliferation defect of the breast CAFs caused by ATM deficiency. Administrating cells with individual or a combination of specific inhibitors of the ERK, PI3K-AKT, and Wnt signaling pathways mimics the effect of ATM deficiency on breast CAF proliferation. This is mainly ascribed to the β-catenin suppression and down-regulation of c-Myc, thus further leading to the decreased cyclinD1, cyclinE, and E2F1 expression and the enhanced p21(Cip1) level. Our results reveal an important role of oxidized ATM in the regulation of the abnormal proliferation of breast CAFs. Oxidized ATM could serve as a potential target for treating breast cancer.

  12. Closed-state inactivation involving an internal gate in Kv4.1 channels modulates pore blockade by intracellular quaternary ammonium ions.

    PubMed

    Fineberg, Jeffrey D; Szanto, Tibor G; Panyi, Gyorgy; Covarrubias, Manuel

    2016-08-09

    Voltage-gated K(+) (Kv) channel activation depends on interactions between voltage sensors and an intracellular activation gate that controls access to a central pore cavity. Here, we hypothesize that this gate is additionally responsible for closed-state inactivation (CSI) in Kv4.x channels. These Kv channels undergo CSI by a mechanism that is still poorly understood. To test the hypothesis, we deduced the state of the Kv4.1 channel intracellular gate by exploiting the trap-door paradigm of pore blockade by internally applied quaternary ammonium (QA) ions exhibiting slow blocking kinetics and high-affinity for a blocking site. We found that inactivation gating seemingly traps benzyl-tributylammonium (bTBuA) when it enters the central pore cavity in the open state. However, bTBuA fails to block inactivated Kv4.1 channels, suggesting gated access involving an internal gate. In contrast, bTBuA blockade of a Shaker Kv channel that undergoes open-state P/C-type inactivation exhibits fast onset and recovery inconsistent with bTBuA trapping. Furthermore, the inactivated Shaker Kv channel is readily blocked by bTBuA. We conclude that Kv4.1 closed-state inactivation modulates pore blockade by QA ions in a manner that depends on the state of the internal activation gate.

  13. Closed-state inactivation involving an internal gate in Kv4.1 channels modulates pore blockade by intracellular quaternary ammonium ions

    PubMed Central

    Fineberg, Jeffrey D.; Szanto, Tibor G.; Panyi, Gyorgy; Covarrubias, Manuel

    2016-01-01

    Voltage-gated K+ (Kv) channel activation depends on interactions between voltage sensors and an intracellular activation gate that controls access to a central pore cavity. Here, we hypothesize that this gate is additionally responsible for closed-state inactivation (CSI) in Kv4.x channels. These Kv channels undergo CSI by a mechanism that is still poorly understood. To test the hypothesis, we deduced the state of the Kv4.1 channel intracellular gate by exploiting the trap-door paradigm of pore blockade by internally applied quaternary ammonium (QA) ions exhibiting slow blocking kinetics and high-affinity for a blocking site. We found that inactivation gating seemingly traps benzyl-tributylammonium (bTBuA) when it enters the central pore cavity in the open state. However, bTBuA fails to block inactivated Kv4.1 channels, suggesting gated access involving an internal gate. In contrast, bTBuA blockade of a Shaker Kv channel that undergoes open-state P/C-type inactivation exhibits fast onset and recovery inconsistent with bTBuA trapping. Furthermore, the inactivated Shaker Kv channel is readily blocked by bTBuA. We conclude that Kv4.1 closed-state inactivation modulates pore blockade by QA ions in a manner that depends on the state of the internal activation gate. PMID:27502553

  14. Redox-optimized ROS balance: a unifying hypothesis

    PubMed Central

    Aon, M.A.; Cortassa, S.; O’Rourke, B.

    2010-01-01

    While it is generally accepted that mitochondrial reactive oxygen species (ROS) balance depends on the both rate of single electron reduction of O2 to superoxide (O2.−) by the electron transport chain and the rate of scavenging by intracellular antioxidant pathways, considerable controversy exists regarding the conditions leading to oxidative stress in intact cells versus isolated mitochondria. Here, we postulate that mitochondria have been evolutionarily optimized to maximize energy output while keeping ROS overflow to a minimum by operating in an intermediate redox state. We show that at the extremes of reduction or oxidation of the redox couples involved in electron transport (NADH/NAD+) or ROS scavenging (NADPH/NADP+, GSH/GSSG), respectively, ROS balance is lost. This results in a net overflow of ROS that increases as one moves farther away from the optimal redox potential. At more reduced mitochondrial redox potentials, ROS production exceeds scavenging, while under more oxidizing conditions (e.g., at higher workloads) antioxidant defenses can be compromised and eventually overwhelmed. Experimental support for this hypothesis is provided in both cardiomyocytes and in isolated mitochondria from guinea pig hearts. The model reconciles, within a single framework, observations that isolated mitochondria tend to display increased oxidative stress at high reduction potentials (and high mitochondrial membrane potential, ΔΨm), whereas intact cardiac cells can display oxidative stress either when mitochondria become more uncoupled (i.e., low ΔΨm) or when mitochondria are maximally reduced (as in ischemia or hypoxia). The continuum described by the model has the potential to account for many disparate experimental observations and also provides a rationale for graded physiological ROS signaling at redox potentials near the minimum. PMID:20175987

  15. Determination of the in vivo redox potential using roGFP and fluorescence spectra obtained from one-wavelength excitation

    NASA Astrophysics Data System (ADS)

    Wierer, S.; Elgass, K.; Bieker, S.; Zentgraf, U.; Meixner, A. J.; Schleifenbaum, F.

    2011-02-01

    The analysis of molecular processes in living (plant) cells such as signal transduction, DNA replication, carbon metabolism and senescence has been revolutionized by the use of green fluorescent protein (GFP) and its variants as specific cellular markers. Many cell biological processes are accompanied by changes in the intracellular redox potential. To monitor the redox potential, a redox-sensitive mutant of GFP (roGFP) was created, which shows changes in its optical properties in response to changes in the redox state of its surrounding medium. For a quantitative analysis in living systems, it is essential to know the optical properties of roGFP in vitro. Therefore, we applied spectrally resolved fluorescence spectroscopy on purified roGFP exposed to different redox potentials to determine shifts in both the absorption and the emission spectra of roGFP. Based on these in vitro findings, we introduce a new approach using one-wavelength excitation to use roGFP for the in vivo analysis of cell biological processes. We demonstrate the ability this technique by investigating chloroplast-located Grx1-roGFP2 expressing Arabidopsis thaliana cells as example for dynamically moving intracellular compartments. This is not possible with the two-wavelength excitation technique established so far, which hampers a quantitative analysis of highly mobile samples due to the time delay between the two measurements and the consequential displacement of the investigated area.

  16. High performance solid-state electric double layer capacitor from redox mediated gel polymer electrolyte and renewable tamarind fruit shell derived porous carbon.

    PubMed

    Senthilkumar, S T; Selvan, R Kalai; Melo, J S; Sanjeeviraja, C

    2013-11-13

    The activated carbon was derived from tamarind fruit shell and utilized as electrodes in a solid state electrochemical double layer capacitor (SSEDLC). The fabricated SSEDLC with PVA (polyvinyl alcohol)/H2SO4 gel electrolyte delivered high specific capacitance and energy density of 412 F g(-1) and 9.166 W h kg(-1), respectively, at 1.56 A g(-1). Subsequently, Na2MoO4 (sodium molybdate) added PVA/H2SO4 gel electrolyte was also prepared and applied for SSEDLC, to improve the performance. Surprisingly, 57.2% of specific capacitance (648 F g(-1)) and of energy density (14.4 Wh kg(-1)) was increased while introducing Na2MoO4 as the redox mediator in PVA/H2SO4 gel electrolyte. This improved performance is owed to the redox reaction between Mo(VI)/Mo(V) and Mo(VI)/Mo(IV) redox couples in Na2MoO4/PVA/H2SO4 gel electrolyte. Similarly, the fabricated device shows the excellent capacitance retention of 93% for over 3000 cycles. The present work suggests that the Na2MoO4 added PVA/H2SO4 gel is a potential electrolyte to improve the performance instead of pristine PVA/H2SO4 gel electrolyte. Based on the overall performance, it is strongly believed that the combination of tamarind fruit shell derived activated carbon and Na2MoO4/PVA/H2SO4 gel electrolyte is more attractive in the near future for high performance SSEDLCs.

  17. Engineering redox balance through cofactor systems.

    PubMed

    Chen, Xiulai; Li, Shubo; Liu, Liming

    2014-06-01

    Redox balance plays an important role in the production of enzymes, pharmaceuticals, and chemicals. To meet the demands of industrial production, it is desirable that microbes maintain a maximal carbon flux towards target metabolites with no fluctuations in redox. This requires functional cofactor systems that support dynamic homeostasis between different redox states or functional stability in a given redox state. Redox balance can be achieved by improving the self-balance of a cofactor system, regulating the substrate balance of a cofactor system, and engineering the synthetic balance of a cofactor system. This review summarizes how cofactor systems can be manipulated to improve redox balance in microbes. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Probing the Protonation State and the Redox-Active Sites of Pendant Base Iron(II) and Zinc(II) Pyridinediimine Complexes.

    PubMed

    Delgado, Mayra; Sommer, Samantha K; Swanson, Seth P; Berger, Robert F; Seda, Takele; Zakharov, Lev N; Gilbertson, John D

    2015-08-03

    Utilizing the pyridinediimine ligand [(2,6-(i)PrC6H3)N═CMe)(N((i)Pr)2C2H4)N═CMe)C5H3N] (didpa), the zinc(II) and iron(II) complexes Zn(didpa)Cl2 (1), Fe(didpa)Cl2 (2), [Zn(Hdidpa)Cl2][PF6] (3), [Fe(Hdidpa)Cl2][PF6] (4), Zn(didpa)Br2 (5), and [Zn(Hdidpa)Br2][PF6] (6), Fe(didpa)(CO)2 (7), and [Fe(Hdidpa)(CO)2][PF6] (8) were synthesized and characterized. These complexes allowed for the study of the secondary coordination sphere pendant base and the redox-activity of the didpa ligand scaffold. The protonated didpa ligand is capable of forming metal halogen hydrogen bonds (MHHBs) in complexes 3, 4, and 6. The solution behavior of the MHHBs was probed via pKa measurements and (1)H NMR titrations of 3 and 6 with solvents of varying H-bond accepting strength. The H-bond strength in 3 and 6 was calculated in silico to be 5.9 and 4.9 kcal/mol, respectively. The relationship between the protonation state and the ligand-based redox activity was probed utilizing 7 and 8, where the reduction potential of the didpa scaffold was found to shift by 105 mV upon protonation of the reduced ligand in Fe(didpa)(CO)2.

  19. Redox-Active Metal-Organic Frameworks: Highly Stable Charge-Separated States through Strut/Guest-to-Strut Electron Transfer.

    PubMed

    Sikdar, Nivedita; Jayaramulu, Kolleboyina; Kiran, Venkayala; Rao, K Venkata; Sampath, Srinivasan; George, Subi J; Maji, Tapas Kumar

    2015-08-10

    Molecular organization of donor and acceptor chromophores in self-assembled materials is of paramount interest in the field of photovoltaics or mimicry of natural light-harvesting systems. With this in mind, a redox-active porous interpenetrated metal-organic framework (MOF), {[Cd(bpdc)(bpNDI)]⋅4.5 H2 O⋅DMF}n (1) has been constructed from a mixed chromophoric system. The μ-oxo-bridged secondary building unit, {Cd2 (μ-OCO)2 }, guides the parallel alignment of bpNDI (N,N'-di(4-pyridyl)-1,4,5,8-naphthalenediimide) acceptor linkers, which are tethered with bpdc (bpdcH2 =4,4'-biphenyldicarboxylic acid) linkers of another entangled net in the framework, resulting in photochromic behaviour through inter-net electron transfer. Encapsulation of electron-donating aromatic molecules in the electron-deficient channels of 1 leads to a perfect donor-acceptor co-facial organization, resulting in long-lived charge-separated states of bpNDI. Furthermore, 1 and guest encapsulated species are characterised through electrochemical studies for understanding of their redox properties.

  20. Evening and morning peroxiredoxin-2 redox/oligomeric state changes in obstructive sleep apnea red blood cells: Correlation with polysomnographic and metabolic parameters.

    PubMed

    Feliciano, Amélia; Vaz, Fátima; Torres, Vukosava M; Valentim-Coelho, Cristina; Silva, Rita; Prosinecki, Vesna; Alexandre, Bruno M; Carvalho, Ana S; Matthiesen, Rune; Malhotra, Atul; Pinto, Paula; Bárbara, Cristina; Penque, Deborah

    2017-02-01

    We have examined the effects of Obstructive Sleep Apnea (OSA) on red blood cell (RBC) proteome variation at evening/morning day time to uncover new insights into OSA-induced RBC dysfunction that may lead to OSA manifestations. Dysregulated proteins mainly fall in the group of catalytic enzymes, stress response and redox regulators such as peroxiredoxin 2 (PRDX2). Validation assays confirmed that at morning the monomeric/dimeric forms of PRDX2 were more overoxidized in OSA RBC compared to evening samples. Six month of positive airway pressure (PAP) treatment decreased this overoxidation and generated multimeric overoxidized forms associated with chaperone/transduction signaling activity of PRDX2. Morning levels of overoxidized PRDX2 correlated with polysomnographic (PSG)-arousal index and metabolic parameters whereas the evening level of disulfide-linked dimer (associated with peroxidase activity of PRDX2) correlated with PSG parameters. After treatment, morning overoxidized multimer of PRDX2 negatively correlated with fasting glucose and dopamine levels. Overall, these data point toward severe oxidative stress and altered antioxidant homeostasis in OSA RBC occurring mainly at morning time but with consequences till evening. The beneficial effect of PAP involves modulation of the redox/oligomeric state of PRDX2, whose mechanism and associated chaperone/transduction signaling functions deserves further investigation. RBC PRDX2 is a promising candidate biomarker for OSA severity and treatment monitoring, warranting further investigation and validation.

  1. Rho GTPases, oxidation, and cell redox control

    PubMed Central

    Hobbs, G Aaron; Zhou, Bingying; Cox, Adrienne D; Campbell, Sharon L

    2014-01-01

    While numerous studies support regulation of Ras GTPases by reactive oxygen and nitrogen species, the Rho subfamily has received considerably less attention. Over the last few years, increasing evidence is emerging that supports the redox sensitivity of Rho GTPases. Moreover, as Rho GTPases regulate the cellular redox state by controlling enzymes that generate and convert reactive oxygen and nitrogen species, redox feedback loops likely exist. Here, we provide an overview of cellular oxidants, Rho GTPases, and their inter-dependence. PMID:24809833

  2. Phosphorus Redox on the Early Earth: First Identification of Low-Oxidation State Phosphorus Compounds in Terrestrial Samples

    NASA Astrophysics Data System (ADS)

    Block, K. M.; Pasek, M. A.

    2008-12-01

    Phosphorus is one of the key elements in biochemical systems, playing an important role in metabolism as ATP and other coenzymes, in replication as DNA and RNA, and in cellular structure as phospholipids. The geochemical cycling of phosphorus on the Earth is usually confined to the rock cycle- redox reactions of phosphorus are never considered. However, it has been proposed that redox reactions of phosphorus were important on the early Earth (Pasek, PNAS 2008). Indeed, such a suggestion is buttressed by the discovery of condensed phosphate formation linked to the oxidation of reduced P compounds. However, prior to the present work, there has been no report of these P compounds in geologic samples. Here we report the first occurrence of reduced P in samples of fulgurites, the glassy material resulting from the fusion of sand, soil, or rock during a lightning strike. On average, lightning strikes the Earth's surface at a rate of approximately 65 times per second (Krider et al., J. Geophys. Res.,1968) exposing target areas to extreme energy dissipation and temperatures. Through electron microprobe analyses and NMR we have identified naturally formed metal droplets containing Fe and P within several fulgurite samples and Ca-phosphite compounds. These droplets are highly reduced compared to the original material and are not naturally present in the target area, rather they were formed through the rapid, intense heating and quenching experienced during fulgurite formation. This process provides a natural means to create localized environments with greater than normal abundances of reduced Fe and P, less commonly found on Earth's surface than their oxidized counterparts. In particular, small areas that receive repeated lightning strikes due to topography or local weather patterns (e.g. hilltops) could potentially house unique microhabitats with reduced elements available for biological use.

  3. Imposed glutathione-mediated redox switch modulates the tobacco wound-induced protein kinase and salicylic acid-induced protein kinase activation state and impacts on defence against Pseudomonas syringae.

    PubMed

    Matern, Sanja; Peskan-Berghoefer, Tatjana; Gromes, Roland; Kiesel, Rebecca Vazquez; Rausch, Thomas

    2015-04-01

    The role of the redox-active tripeptide glutathione in plant defence against pathogens has been studied extensively; however, the impact of changes in cellular glutathione redox potential on signalling processes during defence reactions has remained elusive. This study explored the impact of elevated glutathione content on the cytosolic redox potential and on early defence signalling at the level of mitogen-activated protein kinases (MAPKs), as well as on subsequent defence reactions, including changes in salicylic acid (SA) content, pathogenesis-related gene expression, callose depositions, and the hypersensitive response. Wild-type (WT) Nicotiana tabacum L. and transgenic high-glutathione lines (HGL) were transformed with the cytosol-targeted sensor GRX1-roGFP2 to monitor the cytosolic redox state. Surprisingly, HGLs displayed an oxidative shift in their cytosolic redox potential and an activation of the tobacco MAPKs wound-induced protein kinase (WIPK) and SA-induced protein kinase (SIPK). This activation occurred in the absence of any change in free SA content, but was accompanied by constitutively increased expression of several defence genes. Similarly, rapid activation of MAPKs could be induced in WT tobacco by exposure to either reduced or oxidized glutathione. When HGL plants were challenged with adapted or non-adapted Pseudomonas syringae pathovars, the cytosolic redox shift was further amplified and the defence response was markedly increased, showing a priming effect for SA and callose; however, the initial and transient hyperactivation of MAPK signalling was attenuated in HGLs. The results suggest that, in tobacco, MAPK and SA signalling may operate independently, both possibly being modulated by the glutathione redox potential. Possible mechanisms for redox-mediated MAPK activation are discussed.

  4. Imposed glutathione-mediated redox switch modulates the tobacco wound-induced protein kinase and salicylic acid-induced protein kinase activation state and impacts on defence against Pseudomonas syringae

    PubMed Central

    Matern, Sanja; Peskan-Berghoefer, Tatjana; Gromes, Roland; Kiesel, Rebecca Vazquez; Rausch, Thomas

    2015-01-01

    The role of the redox-active tripeptide glutathione in plant defence against pathogens has been studied extensively; however, the impact of changes in cellular glutathione redox potential on signalling processes during defence reactions has remained elusive. This study explored the impact of elevated glutathione content on the cytosolic redox potential and on early defence signalling at the level of mitogen-activated protein kinases (MAPKs), as well as on subsequent defence reactions, including changes in salicylic acid (SA) content, pathogenesis-related gene expression, callose depositions, and the hypersensitive response. Wild-type (WT) Nicotiana tabacum L. and transgenic high-glutathione lines (HGL) were transformed with the cytosol-targeted sensor GRX1-roGFP2 to monitor the cytosolic redox state. Surprisingly, HGLs displayed an oxidative shift in their cytosolic redox potential and an activation of the tobacco MAPKs wound-induced protein kinase (WIPK) and SA-induced protein kinase (SIPK). This activation occurred in the absence of any change in free SA content, but was accompanied by constitutively increased expression of several defence genes. Similarly, rapid activation of MAPKs could be induced in WT tobacco by exposure to either reduced or oxidized glutathione. When HGL plants were challenged with adapted or non-adapted Pseudomonas syringae pathovars, the cytosolic redox shift was further amplified and the defence response was markedly increased, showing a priming effect for SA and callose; however, the initial and transient hyperactivation of MAPK signalling was attenuated in HGLs. The results suggest that, in tobacco, MAPK and SA signalling may operate independently, both possibly being modulated by the glutathione redox potential. Possible mechanisms for redox-mediated MAPK activation are discussed. PMID:25628332

  5. Metabolic Control of Redox and Redox Control of Metabolism in Plants

    PubMed Central

    Fernie, Alisdair R.

    2014-01-01

    Abstract Significance: Reduction-oxidation (Redox) status operates as a major integrator of subcellular and extracellular metabolism and is simultaneously itself regulated by metabolic processes. Redox status not only dominates cellular metabolism due to the prominence of NAD(H) and NADP(H) couples in myriad metabolic reactions but also acts as an effective signal that informs the cell of the prevailing environmental conditions. After relay of this information, the cell is able to appropriately respond via a range of mechanisms, including directly affecting cellular functioning and reprogramming nuclear gene expression. Recent Advances: The facile accession of Arabidopsis knockout mutants alongside the adoption of broad-scale post-genomic approaches, which are able to provide transcriptomic-, proteomic-, and metabolomic-level information alongside traditional biochemical and emerging cell biological techniques, has dramatically advanced our understanding of redox status control. This review summarizes redox status control of metabolism and the metabolic control of redox status at both cellular and subcellular levels. Critical Issues: It is becoming apparent that plastid, mitochondria, and peroxisome functions influence a wide range of processes outside of the organelles themselves. While knowledge of the network of metabolic pathways and their intraorganellar redox status regulation has increased in the last years, little is known about the interorganellar redox signals coordinating these networks. A current challenge is, therefore, synthesizing our knowledge and planning experiments that tackle redox status regulation at both inter- and intracellular levels. Future Directions: Emerging tools are enabling ever-increasing spatiotemporal resolution of metabolism and imaging of redox status components. Broader application of these tools will likely greatly enhance our understanding of the interplay of redox status and metabolism as well as elucidating and

  6. Ediacaran Redox Fluctuations

    NASA Astrophysics Data System (ADS)

    Sahoo, S. K.; Jiang, G.; Planavsky, N. J.; Kendall, B.; Owens, J. D.; Anbar, A. D.; Lyons, T. W.

    2013-12-01

    Evidence for pervasive oxic conditions, and likely even deep ocean oxygenation has been documented at three intervals in the lower (ca. 632 Ma), middle (ca. 580 Ma) and upper (ca. 551 Ma) Ediacaran. The Doushantuo Formation in South China hosts large enrichments of redox-sensitive trace element (e.g., molybdenum, vanadium and uranium) in anoxic shales, which are indicative of a globally oxic ocean-atmosphere system. However, ocean redox conditions between these periods continue to be a topic of debate and remain elusive. We have found evidence for widespread anoxic conditions through much of the Ediacaran in the deep-water Wuhe section in South China. During most of the Ediacaran-early Cambrian in basinal sections is characterized by Fe speciation data and pyrite morphologies that indicate deposition under euxinic conditions with near-crustal enrichments of redox-sensitive element and positive pyrite-sulfur isotope values, which suggest low levels of marine sulfate and widespread euxinia. Our work reinforces an emerging view that the early Earth, including the Ediacaran, underwent numerous rises and falls in surface oxidation state, rather than a unidirectional rise as originally imagined. The Ediacaran ocean thus experienced repetitive expansion and contraction of marine chalcophilic trace-metal levels that may have had fundamental impact on the slow evolution of early animals and ecosystems. Further, this framework forces us to re-examine the relationship between Neoproterozoic oxygenation and metazoan diversification. Varying redox conditions through the Cryogenian and Ediacaran may help explain molecular clock and biomarker evidence for an early appearance and initial diversification of metazoans but with a delay in the appearance of most major metazoan crown groups until close to Ediacaran-Cambrian boundary.

  7. Intracellular microlasers

    NASA Astrophysics Data System (ADS)

    Humar, Matjaž; Hyun Yun, Seok

    2015-09-01

    Optical microresonators, which confine light within a small cavity, are widely exploited for various applications ranging from the realization of lasers and nonlinear devices to biochemical and optomechanical sensing. Here we use microresonators and suitable optical gain materials inside biological cells to demonstrate various optical functions in vitro including lasing. We explore two distinct types of microresonator—soft and hard—that support whispering-gallery modes. Soft droplets formed by injecting oil or using natural lipid droplets support intracellular laser action. The laser spectra from oil-droplet microlasers can chart cytoplasmic internal stress (˜500 pN μm-2) and its dynamic fluctuations at a sensitivity of 20 pN μm-2 (20 Pa). In a second form, whispering-gallery modes within phagocytized polystyrene beads of different sizes enable individual tagging of thousands of cells easily and, in principle, a much larger number by multiplexing with different dyes.

  8. The Association of Arsenic With Redox Conditions, Depth, and Ground-Water Age in the Glacial Aquifer System of the Northern United States

    USGS Publications Warehouse

    Thomas, Mary Ann

    2007-01-01

    More than 800 wells in the glacial aquifer system of the Northern United States were sampled for arsenic as part of U.S. Geological Survey National Water-Quality Assessment (NAWQA) studies during 1991-2003. Elevated arsenic concentrations (greater than or equal to 10 micrograms per liter) were detected in 9 percent of samples. Elevated arsenic concentrations were associated with strongly reducing conditions. Of the samples classified as iron reducing or sulfate reducing, arsenic concentrations were elevated in 19 percent. Of the methanogenic samples, arsenic concentrations were elevated in 45 percent. In contrast, concentrations of arsenic were elevated in only 1 percent of oxic samples. Arsenic concentrations were also related to ground-water age. Elevated arsenic concentrations were detected in 34 percent of old waters (recharged before 1953) as compared to 4 percent of young waters (recharged since 1953). For samples classified as both old and methanogenic, elevated arsenic concentrations were detected in 62 percent of samples, as compared to 1 percent for samples classified as young and oxic. Arsenic concentrations were also correlated with well depth and concentrations of several chemical constituents, including (1) constituents linked to redox processes and (2) anions or oxyanions that sorb to iron oxides. Observations from the glacial aquifer system are consistent with the idea that the predominant source of arsenic is iron oxides and the predominant mechanism for releasing arsenic to the ground water is reductive desorption or reductive dissolution. Arsenic is also released from iron oxides under oxic conditions, but on a more limited basis and at lower concentrations. Logistic regression was used to investigate the relative significance of redox, ground-water age, depth, and other water-quality constituents as indicators of elevated arsenic concentrations in the glacial aquifer system. The single variable that explained the greatest amount of variation in

  9. Astrocytic Redox Remodeling by Amyloid Beta Peptide

    PubMed Central

    Garg, Sanjay K.; Vitvitsky, Victor; Albin, Roger

    2011-01-01

    Abstract Astrocytes are critical for neuronal redox homeostasis providing them with cysteine needed for glutathione synthesis. In this study, we demonstrate that the astrocytic redox response signature provoked by amyloid beta (Aβ) is distinct from that of a general oxidant (tertiary-butylhydroperoxide [t-BuOOH]). Acute Aβ treatment increased cystathionine β-synthase (CBS) levels and enhanced transsulfuration flux in contrast to repeated Aβ exposure, which decreased CBS and catalase protein levels. Although t-BuOOH also increased transsulfuration flux, CBS levels were unaffected. The net effect of Aβ treatment was an oxidative shift in the intracellular glutathione/glutathione disulfide redox potential in contrast to a reductive shift in response to peroxide. In the extracellular compartment, Aβ, but not t-BuOOH, enhanced cystine uptake and cysteine accumulation, and resulted in remodeling of the extracellular cysteine/cystine redox potential in the reductive direction. The redox changes elicited by Aβ but not peroxide were associated with enhanced DNA synthesis. CBS activity and protein levels tended to be lower in cerebellum from patients with Alzheimer's disease than in age-matched controls. Our study suggests that the alterations in astrocytic redox status could compromise the neuroprotective potential of astrocytes and may be a potential new target for therapeutic intervention in Alzheimer's disease. Antioxid. Redox Signal. 14, 2385–2397. PMID:21235355

  10. Functional aspects of redox control during neuroinflammation.

    PubMed

    Rosales-Corral, Sergio; Reiter, Russel J; Tan, Dun-Xian; Ortiz, Genaro G; Lopez-Armas, Gabriela

    2010-07-15

    Neuroinflammation is a CNS reaction to injury in which some severe pathologies, regardless of their origin, converge. The phenomenon emphasizes crosstalk between neurons and glia and reveals a complex interaction with oxidizing agents through redox sensors localized in enzymes, receptors, and transcription factors. When oxidizing pressures cause reversible molecular changes, such as minimal or transitory proinflammatory cytokine overproduction, redox couples provide a means of translating the presence of reactive oxygen or nitrogen species into useful signals in the cell. Additionally, thiol-based redox sensors convey information about localized changes in redox potential induced by physiologic or pathologic situations. They are susceptible to oxidative changes and become key events during neuroinflammation, altering the course of a signaling response or the behavior of specific transcription factors. When oxidative stress augments the pressure on the intracellular environment, the effective reduction potential of redox pairs diminishes, and cell signaling shifts toward proinflammatory and proapoptotic signals, creating a vicious cycle between oxidative stress and neuroinflammation. In addition, electrophilic compounds derived from the oxidative cascade react with key protein thiols and interfere with redox signaling. This article reviews the relevant functional aspects of redox control during the neuroinflammatory process.

  11. Factors Controlling Redox Speciation of Plutonium and Neptunium in Extraction Separation Processes

    SciTech Connect

    Paulenova, Alena; Vandegrift, III, George F.

    2013-09-24

    The objective of the project was to examine the factors controlling redox speciation of plutonium and neptunium in UREX+ extraction in terms of redox potentials, redox mechanism, kinetics and thermodynamics. Researchers employed redox-speciation extractions schemes in parallel to the spectroscopic experiments. The resulting distribution of redox species w studied uring spectroscopic, electrochemical, and spectro-electrochemical methods. This work reulted in collection of data on redox stability and distribution of redox couples in the nitric acid/nitrate electrolyte and the development of redox buffers to stabilize the desired oxidation state of separated radionuclides. The effects of temperature and concentrations on the redox behavior of neptunium were evaluated.

  12. Characterization of redox states of Ru(OH(2))(Q)(tpy)(2+) (Q = 3,5-di-tert-butyl-1,2-benzoquinone, tpy = 2,2':6',2''-terpyridine) and related species through experimental and theoretical studies.

    PubMed

    Tsai, Ming-Kang; Rochford, Jonathan; Polyansky, Dmitry E; Wada, Tohru; Tanaka, Koji; Fujita, Etsuko; Muckerman, James T

    2009-05-18

    The redox states of Ru(OH(2))(Q)(tpy)(2+) (Q = 3,5-di-tert-butyl-1,2-benzoquinone, tpy = 2,2':6',2''-terpyridine) are investigated through experimental and theoretical UV-vis spectra and Pourbaix diagrams. The electrochemical properties are reported for the species resulting from deprotonation and redox processes in aqueous solution. The formal oxidation states of the redox couples in the various intermediate complexes are systematically assigned using electronic structure theory. The controversy over the electronic assignment of ferromagnetic vs. antiferromagnetic coupling is investigated through comparison of ab initio methods and the broken-symmetry density functional theory (DFT) approach. The various pK(a) values and reduction potentials, including the consideration of proton-coupled electron-transfer (PCET) processes, are calculated, and the theoretical version of the Pourbaix diagram is constructed in order to elucidate and assign several previously ambiguous regions in the experimental diagram.

  13. The effect of the oxidation state of a terthiophene-conducting polymer and of the presence of a redox probe on its gene-sensing properties.

    PubMed

    Spires, John B; Peng, Hui; Williams, David E; Wright, Bryon E; Soeller, Christian; Travas-Sejdic, Jadranka

    2008-12-01

    The gene-sensing properties of sensor films made of a terthiophene-conducting polymer, poly(3-((2':2'', 5'':2'''-terthiophene)-3''-yl)acrylic acid) (PTAA), were evaluated using electrochemical impedance spectroscopy for films in their reduced and oxidised states with and without the Fe(CN)(6)(3-/4-) redox probe (RP) in dilute tris-EDTA buffer. Porous films of PTAA were prepared and attached to an oligonucleotide sequence specific to the Salmonella virulence gene InvA. These films could be described with a dual transmission line model in which the polymer conductivity was increased as a consequence of surface binding of complementary DNA. The effect is analogous to that reported for silicon nanowires and field-effect transistors in dilute electrolyte modified by charge exchange across the polymer-electrolyte interface. As a result, gene sensing could be conveniently observed as a change in the impedance phase angle at a fixed frequency.

  14. In Situ Tuning of Magnetization and Magnetoresistance in Fe3O4 Thin Film Achieved with All-Solid-State Redox Device.

    PubMed

    Tsuchiya, Takashi; Terabe, Kazuya; Ochi, Masanori; Higuchi, Tohru; Osada, Minoru; Yamashita, Yoshiyuki; Ueda, Shigenori; Aono, Masakazu

    2016-01-26

    An all-solid-state redox device composed of Fe3O4 thin film and Li(+) ion conducting solid electrolyte was fabricated for use in tuning magnetization and magnetoresistance (MR), which are key factors in the creation of high-density magnetic storage devices. Electrical conductivity, magnetization, and MR were reversibly tuned by Li(+) insertion and removal. Tuning of the various Fe3O4 thin film properties was achieved by donation of an electron to the Fe(3+) ions. This technique should lead to the development of spintronics devices based on the reversible switching of magnetization and spin polarization (P). It should also improve the performance of conventional magnetic random access memory (MRAM) devices in which the ON/OFF ratio has been limited to a small value due to a decrease in P near the tunnel barrier.

  15. Analysis of downregulation of cellular energy demand by 2D measurements of intracapillary HbO2, Hb, pO2, and redox state of cytochromes

    NASA Astrophysics Data System (ADS)

    Krug, Alfons; Kessler, Manfred D.; Hoeper, Jens; Zellner, S.; Sourdoulaud, Valerie

    1995-04-01

    Rapid microlightguide spectrometers (EMPHO IIa/b) and a multiwire pO2 electrode are applied for measurements of heterogeneous distribution of tissue oxygenation and redox state of respiratory enzymes in heart and rat liver. Optical and pO2 measurements are noninvasively performed by use of sensors placed on the surface of tissue. Measurements in isolated perfused rat and in dog heart in situ were performed in order to investigate the relation between myocardial oxygenation and function. The tissue monitoring in liver was initiated by optical and polarographic monitoring in the hemoglobin free perfused organ. Subsequently, erythrocytes were added to the perfusate in several steps. The experiments reveal clear evidence that a protective system of tissue is activated when critical pO2 values at the lethal corner of micro vessels fall off a critical threshold around 5 mmHg, thus causing a depletion of oxidative metabolism.

  16. Temporal distribution of mantle-derived potassic rocks and carbonatites linked to stabilization of mantle lithosphere and redox states during subduction

    NASA Astrophysics Data System (ADS)

    Foley, S. F.

    2014-12-01

    Mantle-derived potassic igneous rocks and carbonatites first appear in the geological record in the late Archean, coinciding with major crust-forming events on most continents. The compositions of potassic rocks require sources including discrete ultramafic rocks with phlogopite and pyroxenes, whereas carbonatites and ultramafic lamprophyres (carbonate-rich potassic rocks) require oxidizing conditions in which carbonate is stable. The presence of these source rocks from this time is probably related to the stabilization of mantle lithosphere. If mantle lithosphere had not been stable for considerable periods of time, then melting would be restricted to peridotite, which is not a viable option for strongly potassic rocks. The phlogopite-rich source-rock assemblages that are necessary precursors for potassic melts could be introduced into the lithosphere by either subduction processes or by multiple stages of low-degree melting. Many modern examples involve subducted sedimentary material, which concentrates potassium by the stabilization of micas in subduction metamorphism. Subduction involves a great variety of redox states, but the bulk effect is the return of oxidized material from the surface into the mantle. However, we cannot apply uniformitarianism unthinkingly, because subduction processes at and before 2.7 Ga may have had different redox states. Before the Great Oxidation Event the distribution and abundances of geological formations such as banded iron formations, red beds, and uraninites indicate that geological reservoirs became gradually oxidized, preventing an earlier increase in atmospheric oxygen. This means that the function of the subduction process to oxidize the upper mantle by the return of oxidized rocks from the surface was much weaker in the early Earth. Early continental mantle lithosphere was, therefore, likely to accumulate carbon in reduced form, which would be more easily remobilized in melts through low-temperature redox melting much

  17. Oxidative Stress in Mammalian Cells Impinges on the Cysteines Redox State of Human XRCC3 Protein and on Its Cellular Localization

    PubMed Central

    Girard, Pierre-Marie; Graindorge, Dany; Smirnova, Violetta; Rigolet, Pascal; Francesconi, Stefania; Scanlon, Susan; Sage, Evelyne

    2013-01-01

    In vertebrates, XRCC3 is one of the five Rad51 paralogs that plays a central role in homologous recombination (HR), a key pathway for maintaining genomic stability. While investigating the potential role of human XRCC3 (hXRCC3) in the inhibition of DNA replication induced by UVA radiation, we discovered that hXRCC3 cysteine residues are oxidized following photosensitization by UVA. Our in silico prediction of the hXRCC3 structure suggests that 6 out of 8 cysteines are potentially accessible to the solvent and therefore potentially exposed to ROS attack. By non-reducing SDS-PAGE we show that many different oxidants induce hXRCC3 oxidation that is monitored in Chinese hamster ovarian (CHO) cells by increased electrophoretic mobility of the protein and in human cells by a slight decrease of its immunodetection. In both cell types, hXRCC3 oxidation was reversed in few minutes by cellular reducing systems. Depletion of intracellular glutathione prevents hXRCC3 oxidation only after UVA exposure though depending on the type of photosensitizer. In addition, we show that hXRCC3 expressed in CHO cells localizes both in the cytoplasm and in the nucleus. Mutating all hXRCC3 cysteines to serines (XR3/S protein) does not affect the subcellular localization of the protein even after exposure to camptothecin (CPT), which typically induces DNA damages that require HR to be repaired. However, cells expressing mutated XR3/S protein are sensitive to CPT, thus highlighting a defect of the mutant protein in HR. In marked contrast to CPT treatment, oxidative stress induces relocalization at the chromatin fraction of both wild-type and mutated protein, even though survival is not affected. Collectively, our results demonstrate that the DNA repair protein hXRCC3 is a target of ROS induced by environmental factors and raise the possibility that the redox environment might participate in regulating the HR pathway. PMID:24116071

  18. Effects of morin-5'-sulfonic acid sodium salt (NaMSA) on cyclophosphamide-induced changes in oxido-redox state in rat liver and kidney.

    PubMed

    Merwid-Ląd, A; Trocha, M; Chlebda, E; Sozański, T; Magdalan, J; Ksiądzyna, D; Kopacz, M; Kuźniar, A; Nowak, D; Pieśniewska, M; Fereniec-Gołębiewska, L; Kwiatkowska, J; Szeląg, A

    2012-08-01

    Cyclophosphamide (CPX) is an anticancer drug with immunosuppressive properties. Its adverse effects are partly connected to the induction of oxidative stress. Some studies indicate that water-soluble derivative of morin-morin-5'-sulfonic acid sodium salt (NaMSA) exhibits strong antioxidant activity. The aim of present study was to evaluate the effect of NaMSA on CPX-induced changes in oxido-redox state in rat. Experiment was carried out on Wistar rats divided in three experimental groups (N = 12) receiving: 0.9% saline, CPX (15 mg/kg) or CPX (15 mg/kg) + NaMSA (100 mg/kg), respectively, and were given intragastrically for 10 days. Malondialdehyde (MDA) and glutathione (GSH) concentrations and superoxide dismutase (SOD) activity were determined in liver and kidneys. Catalase (CAT) activity was assessed only in liver. Treatment with CPX resulted in significant decrease in MDA level in both tissues, which was completely reversed by NaMSA treatment only in liver. In comparison to the control group significant decrease in SOD activity were observed in both tissues of CPX receiving group. In kidneys this parameter was fully restored by NaMSA administration. CPX evoked significant decrease in GSH concentration in kidneys, which was completely reversed by NaMSA treatment. No significant changes were seen in GSH levels and CAT activity between all groups in liver. Results of our study suggest that CPX may exert significant impact on oxido-redox state in both organs. NaMSA fully reversed the CPX-induced changes, especially MDA level in liver, SOD activity and GSH concentration in kidneys and it may be done by enhancement of activity/concentration of endogenous antioxidants.

  19. Drought-Induced Changes in the Redox State of α-Tocopherol, Ascorbate, and the Diterpene Carnosic Acid in Chloroplasts of Labiatae Species Differing in Carnosic Acid Contents1

    PubMed Central

    Munné-Bosch, Sergi; Alegre, Leonor

    2003-01-01

    To assess antioxidative protection by carnosic acid (CA) in combination with that of other low-molecular weight (Mr) antioxidants (α-tocopherol [α-T] and ascorbate [Asc]) in chloroplasts, we measured endogenous concentrations of these antioxidants, their redox states, and other indicators of oxidative stress in chloroplasts of three Labiatae species, differing in their CA contents, exposed to drought stress in the field. Damage to the photosynthetic apparatus was observed neither in CA-containing species (rosemary [Rosmarinus officinalis]) and sage [Salvia officinalis]) nor in CA-free species (lemon balm [Melissa officinalis]) at relative leaf water contents between 86% and 58%, as indicated by constant maximum efficiency of photosystem II photochemistry ratios and malondialdehyde levels in chloroplasts. The three species showed significant increases in α-T, a shift of the redox state of α-T toward its reduced state, and increased Asc levels in chloroplasts under stress. Lemon balm showed the highest increases in α-T and Asc in chloroplasts under stress, which might compensate for the lack of CA. Besides, whereas in rosemary and sage, the redox state of CA was shifted toward its oxidized state and the redox state of Asc was kept constant, lemon balm displayed a shift of the redox state of Asc toward its oxidized state under stress. In vitro experiments showed that both CA and Asc protect α-T and photosynthetic membranes against oxidative damage. These results are consistent with the contention that CA, in combination with other low-Mr antioxidants, helps to prevent oxidative damage in chloroplasts of water-stressed plants, and they show functional interdependence among different low-Mr antioxidants in chloroplasts. PMID:12692341

  20. Development of redox-sensitive red fluorescent proteins for imaging redox dynamics in cellular compartments.

    PubMed

    Fan, Yichong; Ai, Hui-wang

    2016-04-01

    We recently reported a redox-sensitive red fluorescent protein, rxRFP1, which is one of the first genetically encoded red-fluorescent probes for general redox states in living cells. As individual cellular compartments have different basal redox potentials, we hereby describe a group of rxRFP1 mutants, showing different midpoint redox potentials for detection of redox dynamics in various subcellular domains, such as mitochondria, the cell nucleus, and endoplasmic reticulum (ER). When these redox probes were expressed and subcellularly localized in human embryonic kidney (HEK) 293 T cells, they responded to membrane-permeable oxidants and reductants. In addition, a mitochondrially localized rxRFP1 mutant, Mito-rxRFP1.1, was used to detect mitochondrial oxidative stress induced by doxorubicin-a widely used cancer chemotherapy drug. Our work has expanded the fluorescent protein toolkit with new research tools for studying compartmentalized redox dynamics and oxidative stress under various pathophysiological conditions.

  1. Tendency for oxidation of annelid hemoglobin at alkaline pH and dissociated states probed by redox titration.

    PubMed

    Bispo, Jose Ailton Conceicao; Landini, Gustavo Fraga; Santos, Jose Luis Rocha; Norberto, Douglas Ricardo; Bonafe, Carlos Francisco Sampaio

    2005-08-01

    The redox titration of extracellular hemoglobin of Glossoscolex paulistus (Annelidea) was investigated in different pH conditions and after dissociation induced by pressure. Oxidation increased with increasing pH, as shown by the reduced amount of ferricyanide necessary for the oxidation of hemoglobin. This behavior was the opposite of that of vertebrate hemoglobins. The potential of half oxidation (E1/2) changed from -65.3 to +146.8 mV when the pH increased from 4.50 to 8.75. The functional properties indicated a reduction in the log P50 from 1.28 to 0.28 in this pH range. The dissociation at alkaline pH or induced by high pressure, confirmed by HPLC gel filtration, suggested that disassembly of the hemoglobin could be involved in the increased potential for oxidation. These results suggest that the high stability and prolonged lifetime common to invertebrate hemoglobins is related to their low tendency to oxidize at acidic pH, in contrast to vertebrate hemoglobins.

  2. DNA and redox state induced conformational changes in the DNA-binding domain of the Myb oncoprotein.

    PubMed Central

    Myrset, A H; Bostad, A; Jamin, N; Lirsac, P N; Toma, F; Gabrielsen, O S

    1993-01-01

    The DNA-binding domain of the oncoprotein Myb comprises three imperfect repeats, R1, R2 and R3. Only R2 and R3 are required for sequence-specific DNA-binding. Both are assumed to contain helix-turn-helix (HTH)-related motifs, but multidimensional heteronuclear NMR spectroscopy revealed a disordered structure in R2 where the second HTH helix was predicted [Jamin et al. (1993) Eur. J. Biochem., 216, 147-154]. We propose that the disordered region folds into a 'recognition' helix and generates a full HTH-related motif upon binding to DNA. This would move Cys43 into the hydrophobic core of R2. We observed that Cys43 was accessible to N-ethylmaleimide alkylation in the free protein, but inaccessible in the DNA complex. Mutant proteins with charged (C43D) or polar (C43S) side chains in position 43 bound DNA with reduced affinity, while hydrophobic replacements (C43A, C43V and C43I) gave unaltered or improved DNA-binding. Specific DNA-binding enhanced protease resistance dramatically. Fluorescence emission spectra and quenching experiments supported a DNA-induced conformational change. Moreover, reversible oxidation of Cys43 had an effect similar to the inactivating C43D mutation. The highly oxidizable Cys43 could function as a molecular sensor for a redox regulatory mechanism turning specific DNA-binding on or off by controlling the DNA-induced conformational change in R2. Images PMID:8223472

  3. The Influence of Metal Stress on the Availability and Redox State of Ascorbate, and Possible Interference with Its Cellular Functions

    PubMed Central

    Bielen, An; Remans, Tony; Vangronsveld, Jaco; Cuypers, Ann

    2013-01-01

    Worldwide, metals have been distributed to excessive levels in the environment due to industrial and agricultural activities. Plants growing on soils contaminated with excess levels of metals experience a disturbance of the cellular redox balance, which leads to an augmentation of reactive oxygen species (ROS). Even though the increased ROS levels can cause cellular damage, controlled levels play an important role in modulating signaling networks that control physiological processes and stress responses. Plants control ROS levels using their antioxidative defense system both under non-stress conditions, as well as under stress conditions such as exposure to excess metals. Ascorbate (AsA) is a well-known and important component of the plant’s antioxidative system. As primary antioxidant, it can reduce ROS directly and indirectly via ascorbate peroxidase in the ascorbate–glutathione cycle. Furthermore, AsA fulfills an essential role in physiological processes, some of which are disturbed by excess metals. In this review, known direct effects of excess metals on AsA biosynthesis and functioning will be discussed, as well as the possible interference of metals with the role of AsA in physiological and biochemical processes. PMID:23519107

  4. A cell cycle-controlled redox switch regulates the topoisomerase IV activity

    PubMed Central

    Narayanan, Sharath; Janakiraman, Balaganesh; Kumar, Lokesh

    2015-01-01

    Topoisomerase IV (topo IV), an essential factor during chromosome segregation, resolves the catenated chromosomes at the end of each replication cycle. How the decatenating activity of the topo IV is regulated during the early stages of the chromosome cycle despite being in continuous association with the chromosome remains poorly understood. Here we report a novel cell cycle-regulated protein in Caulobacter crescentus, NstA (negative switch for topo IV decatenation activity), that inhibits the decatenation activity of the topo IV during early stages of the cell cycle. We demonstrate that in C. crescentus, NstA acts by binding to the ParC DNA-binding subunit of topo IV. Most importantly, we uncover a dynamic oscillation of the intracellular redox state during the cell cycle, which correlates with and controls NstA activity. Thus, we propose that predetermined dynamic intracellular redox fluctuations may act as a global regulatory switch to control cellular development and cell cycle progression and may help retain pathogens in a suitable cell cycle state when encountering redox stress from the host immune response. PMID:26063575

  5. Two open states and rate-limiting gating steps revealed by intracellular Na+ block of human KCNQ1 and KCNQ1/KCNE1 K+ channels

    PubMed Central

    Pusch, Michael; Ferrera, Loretta; Friedrich, Thomas

    2001-01-01

    KCNQ1, the first member of a new K+ channel family, associates with the small KCNE1 subunit to form the slow cardiac delayed rectifier current, IKs. Mutations in both genes encoding these channels lead to cardiac arrhythmia. We studied the block by intracellular Na+ of human homomeric KCNQ1 (homomers) and heteromeric KCNQ1/KCNE1 (heteromers) expressed in CHO cells (Chinese hamster ovary cell line) using whole-cell patch recording. In the nominal absence of extracellular K+ and with 65 mm intracellular K+, the replacement of 65 mm intracellular N-methyl-d-glucamine (NMDG+) by 65 mm Na+ induced a decay of outward (K+) currents through homomers after maximal activation reminiscent of an inactivation process. The decay had a time constant in the hundreds of milliseconds range. The inactivation process of homomers was, however, not directly dependent on [Na+]i, as evidenced by unaltered biphasic deactivation at negative voltages. An instantaneous voltage-dependent Na+ block of homomers was revealed using tail current protocols with activating prepulses that saturated the gating processes of the channel. The instantaneous block was partially relieved at very large positive voltages (≥ 60 mV) and in 20 mm extracellular K+. The instantaneous block of homomers was much less pronounced if the tail currents were measured after short activating prepulses, demonstrating the presence of (at least) two open states: a first, relatively [Na+]i-insensitive and a subsequent [Na+]i-sensitive open state; the current decay reflects the transition between the two open states. Heteromers exhibited a very similar instantaneous block by Nai+ independently of the prepulse duration. Heteromers did not show a Nai+-induced current decay. Our results demonstrate the presence of two open states of KCNQ1 channels with different [Na+]i sensitivities. The rate-limiting step of homomeric KCNQ1 gating at positive voltages is the transition between these two open states. The rate-limiting step of the

  6. Two open states and rate-limiting gating steps revealed by intracellular Na+ block of human KCNQ1 and KCNQ1/KCNE1 K+ channels.

    PubMed

    Pusch, M; Ferrera, L; Friedrich, T

    2001-05-15

    KCNQ1, the first member of a new K+ channel family, associates with the small KCNE1 subunit to form the slow cardiac delayed rectifier current, IKs. Mutations in both genes encoding these channels lead to cardiac arrhythmia. We studied the block by intracellular Na+ of human homomeric KCNQ1 (homomers) and heteromeric KCNQ1/KCNE1 (heteromers) expressed in CHO cells (Chinese hamster ovary cell line) using whole-cell patch recording. In the nominal absence of extracellular K+ and with 65 mM intracellular K+, the replacement of 65 mM intracellular N-methyl-D-glucamine (NMDG+) by 65 mM Na+ induced a decay of outward (K+) currents through homomers after maximal activation reminiscent of an inactivation process. The decay had a time constant in the hundreds of milliseconds range. The inactivation process of homomers was, however, not directly dependent on [Na+]i, as evidenced by unaltered biphasic deactivation at negative voltages. An instantaneous voltage-dependent Na+ block of homomers was revealed using tail current protocols with activating prepulses that saturated the gating processes of the channel. The instantaneous block was partially relieved at very large positive voltages (> or = 60 mV) and in 20 mM extracellular K+. The instantaneous block of homomers was much less pronounced if the tail currents were measured after short activating prepulses, demonstrating the presence of (at least) two open states: a first, relatively [Na+]i-insensitive and a subsequent [Na+]i-sensitive open state; the current decay reflects the transition between the two open states. Heteromers exhibited a very similar instantaneous block by Na+i independently of the prepulse duration. Heteromers did not show a Na+i-induced current decay. Our results demonstrate the presence of two open states of KCNQ1 channels with different [Na+]i sensitivities. The rate-limiting step of homomeric KCNQ1 gating at positive voltages is the transition between these two open states. The rate-limiting step of

  7. Redox state of near infrared spectroscopy-measured cytochrome aa(3) correlates with delayed cerebral energy failure following perinatal hypoxia-ischaemia in the newborn pig.

    PubMed

    Peeters-Scholte, Cacha; van den Tweel, Evelyn; Groenendaal, Floris; van Bel, Frank

    2004-05-01

    Early detection of delayed cerebral energy failure may be important in the prevention of reperfusion injury of the brain after severe perinatal hypoxia-ischaemia (HI). This study investigated whether monitoring of the redox state of cytochrome aa(3) (Cytaa(3)) with near infrared spectroscopy (NIRS) after severe perinatal asphyxia may allow us to detect early a compromised energy metabolism of the developing brain. We therefore correlated serial Cytaa(3) measurements (to estimate mitochondrial oxygenation) simultaneously with the (31)phosphorous-magnetic resonance spectroscopy ((31)P-MRS)-measured phosphocreatin/inorganic phosphate (PCr/Pi) ratio (to estimate cerebral energy reserve) in newborn piglets before and after severe hypoxia-ischaemia. The animals were treated upon reperfusion with either allopurinol, deferoxamine, or 2-iminobiotin or with a vehicle to reduce post-HI reperfusion injury of the brain. Four sham-operated piglets served as controls. Before HI, the individual Cytaa(3) values ranged between -0.02 and 0.71 micromol/L (mean value: -0.07) relative to baseline. The pattern over post-HI time of the vehicle-treated animals was remarkably different from the other groups in as far Cytaa(3) became more oxidised from 3 h after start of HI onwards (increase of Cytaa(3) as compared with baseline), whereas the other groups showed a significant reduction over time (decrease of Cytaa(3) as compared with baseline: allopurinol and deferoxamine) or hardly any change (2-iminobiotin and sham-operated piglets). Vehicle-treated piglets showed a significant reduction in PCr/Pi at 24 h after start of HI, but the cerebral energy state was preserved in 2-iminobiotin-, allopurinol- and deferoxamine-treated piglets. With severe reduction in PCr/Pi-ratio, major changes in the redox-state of Cytaa(3) also occurred: Cytaa(3) was mostly either in a reduced state (down to -6.45 micromol/L) or in an oxidised state (up to 6.84 micromol/L) at these low PCr/Pi ratios. The positive

  8. Cysteine Mutational Studies Provide Insight into a Thiol-Based Redox Switch Mechanism of Metal and DNA Binding in FurA from Anabaena sp. PCC 7120

    PubMed Central

    Botello-Morte, Laura; Pellicer, Silvia; Sein-Echaluce, Violeta C.; Contreras, Lellys M.; Neira, José Luis; Abián, Olga; Velázquez-Campoy, Adrián; Peleato, María Luisa; Fillat, María F.

    2016-01-01

    Abstract Aims: The ferric uptake regulator (Fur) is the main transcriptional regulator of genes involved in iron homeostasis in most prokaryotes. FurA from Anabaena sp. PCC 7120 contains five cysteine residues, four of them arranged in two redox-active CXXC motifs. The protein needs not only metal but also reducing conditions to remain fully active in vitro. Through a mutational study of the cysteine residues present in FurA, we have investigated their involvement in metal and DNA binding. Results: Residue C101 that belongs to a conserved CXXC motif plays an essential role in both metal and DNA binding activities in vitro. Substitution of C101 by serine impairs DNA and metal binding abilities of FurA. Isothermal titration calorimetry measurements show that the redox state of C101 is responsible for the protein ability to coordinate the metal corepressor. Moreover, the redox state of C101 varies with the presence or absence of C104 or C133, suggesting that the environments of these cysteines are mutually interdependent. Innovation: We propose that C101 is part of a thiol/disulfide redox switch that determines FurA ability to bind the metal corepressor. Conclusion: This mechanism supports a novel feature of a Fur protein that emerges as a regulator, which connects the response to changes in the intracellular redox state and iron management in cyanobacteria. Antioxid. Redox Signal. 24, 173–185. PMID:26414804

  9. Depth Variations in Redox State and Fluid Mobile Element Enrichments in the Mantle Wedge Beneath the Cascades

    NASA Astrophysics Data System (ADS)

    Agranier, A.; Lee, C.; Leeman, W.

    2005-12-01

    define fO2 conditions in the group-1 and group-2 sources of magmas. V/Sc ratio is a choice index to evaluate redox conditions in sources of these lavas because V is redox sensitive whereas Sc is not. From our dataset, group-1 magmas have uniform V/Sc ratios which are significantly lower than those of Group-2 (5.7 vs.7.7 to 9.1, respectively). Considering these basalts as the product of about 10% of partial melting, we can estimate (after Lee et al., 2005) that fO2 in the sources of group-1 and group-2 lavas were different (about FMQ-1 and FMQ respectively). The influence of garnet retention in the source could have had on the V/Sc of basalts has been explored but does not seems to be significant in this case.

  10. Inhibition of testosterone biosynthesis by ethanol. Relation to hepatic and testicular acetaldehyde, ketone bodies and cytosolic redox state in rats.

    PubMed Central

    Eriksson, C J; Widenius, T V; Ylikahri, R H; Härkönen, M; Leinonen, P

    1983-01-01

    In experiments in which liver and testis freeze-stops were performed on pentobarbital-anaesthetized rats, ethanol (1.5 g/kg body wt.) reduced plasma testosterone concentration from 13.1 to 3.2 nmol/litre. 4-Methylpyrazole abolished the ethanol-induced hepatic and testicular increase in the lactate/pyruvate ratio, and the testicular acetaldehyde level, but did not diminish the reduction in plasma testosterone concentration. In testes, but not in liver, ethanol decreased the 3-hydroxybutyrate/acetoacetate ratio, and 4-methylpyrazole did not prevent this effect. In experiments in which freeze-stop was performed after cervical dislocation, ethanol decreased the testis testosterone concentration from 590 to 220 pmol per g wet wt. The effects of ethanol and 4-methylpyrazole on testis acetaldehyde, lactate/pyruvate and 3-hydroxybutyrate/acetoacetate ratios were the same as found during anaesthesia. The NAD+-dependent ethanol oxidation capacity in testis ranged from 0.1 to 0.2 mumol/min per g wet wt. and seemed to be inhibited by 4-methylpyrazole both in vivo and in vitro. In additional experiments, ethanol doses between 0.3 and 0.9 g/kg body wt. did not alter the plasma testosterone concentration in rats treated, or not treated, with cyanamide, which induced elevated acetaldehyde levels in blood and testes. The results suggest that ethanol-induced inhibition of testosterone biosynthesis was not caused by extratesticular redox increases, or by extra- or intra-testicular acetaldehyde per se. The inhibition is accompanied by changes in testicular ketone-body metabolism. PMID:6847648

  11. Redox chemistry of selenenic acids and the insight it brings on transition state geometry in the reactions of peroxyl radicals.

    PubMed

    Zielinski, Zosia; Presseau, Nathalie; Amorati, Riccardo; Valgimigli, Luca; Pratt, Derek A

    2014-01-29

    The redox chemistry of selenenic acids has been explored for the first time using a persistent selenenic acid, 9-triptyceneselenenic acid (RSeOH), and the results have been compared with those we recently obtained with its lighter chalcogen analogue, 9-triptycenesulfenic acid (RSOH). Specifically, the selenenyl radical was characterized by EPR spectroscopy and equilibrated with a phenoxyl radical of known stability in order to determine the O-H bond dissociation enthalpy of RSeOH (80.9 ± 0.8 kcal/mol): ca. 9 kcal/mol stronger than in RSOH. Kinetic measurements of the reactions of RSeOH with peroxyl radicals demonstrate that it readily undergoes H-atom transfer reactions (e.g., k = 1.7 × 10(5) M(-1) s(-1) in PhCl), which are subject to kinetic solvent effects and kinetic isotope effects similar to RSOH and other good H-atom donors. Interestingly, the rate constants for these reactions are only 18- and 5-fold smaller than those measured for RSOH in PhCl and CH3CN, respectively, despite being 9 kcal/mol less exothermic for RSeOH. IR spectroscopic studies demonstrate that RSeOH is less H-bond acidic than RSOH, accounting for these solvent effects and enabling estimates of the pKas in RSeOH and RSOH of ca. 15 and 10, respectively. Calculations suggest that the TS structures for these reactions have significant charge transfer between the chalcogen atom and the internal oxygen atom of the peroxyl radical, which is nominally better for the more polarizable selenenic acid. The higher than expected reactivity of RSeOH toward peroxyl radicals is the strongest experimental evidence to date for charge transfer/secondary orbital interactions in the reactions of peroxyl radicals with good H-atom donors.

  12. The Redox State Regulates the Conformation of Rv2466c to Activate the Antitubercular Prodrug TP053*

    PubMed Central

    Albesa-Jové, David; Comino, Natalia; Tersa, Montse; Mohorko, Elisabeth; Urresti, Saioa; Dainese, Elisa; Chiarelli, Laurent R.; Pasca, Maria Rosalia; Manganelli, Riccardo; Makarov, Vadim; Riccardi, Giovanna; Svergun, Dmitri I.; Glockshuber, Rudi; Guerin, Marcelo E.

    2015-01-01

    Rv2466c is a key oxidoreductase that mediates the reductive activation of TP053, a thienopyrimidine derivative that kills replicating and non-replicating Mycobacterium tuberculosis, but whose mode of action remains enigmatic. Rv2466c is a homodimer in which each subunit displays a modular architecture comprising a canonical thioredoxin-fold with a Cys19-Pro20-Trp21-Cys22 motif, and an insertion consisting of a four α-helical bundle and a short α-helical hairpin. Strong evidence is provided for dramatic conformational changes during the Rv2466c redox cycle, which are essential for TP053 activity. Strikingly, a new crystal structure of the reduced form of Rv2466c revealed the binding of a C-terminal extension in α-helical conformation to a pocket next to the active site cysteine pair at the interface between the thioredoxin domain and the helical insertion domain. The ab initio low-resolution envelopes obtained from small angle x-ray scattering showed that the fully reduced form of Rv2466c adopts a “closed” compact conformation in solution, similar to that observed in the crystal structure. In contrast, the oxidized form of Rv2466c displays an “open” conformation, where tertiary structural changes in the α-helical subdomain suffice to account for the observed conformational transitions. Altogether our structural, biochemical, and biophysical data strongly support a model in which the formation of the catalytic disulfide bond upon TP053 reduction triggers local structural changes that open the substrate binding site of Rv2466c allowing the release of the activated, reduced form of TP053. Our studies suggest that similar structural changes might have a functional role in other members of the thioredoxin-fold superfamily. PMID:26546681

  13. High-resolution imaging of labile phosphorus and its relationship with iron redox state in lake sediments.

    PubMed

    Gao, Yulu; Liang, Tao; Tian, Shuhan; Wang, Lingqing; Holm, Peter E; Bruun Hansen, Hans Christian

    2016-12-01

    A thorough understanding of the labile status and dynamics of phosphorus (P) and iron (Fe) across the sediment-water interface (SWI) is essential for managing internal P release in eutrophic lakes. Fe-coupled inactivation of P in sediments is an important factor which affects internal P release in freshwater lakes. In this study, two in-situ high-resolution diffusive gradients in thin films (DGT) techniques, Zr-Oxide DGT and ZrO-Chelex DGT, were used to investigate the release characteristics of P from sediments in a large freshwater lake (Dongting Lake, China; area of 2691 km(2)) experiencing a regional summer algal bloom. Two-dimensional distributions of labile P in sediments were imaged with the Zr-Oxide DGT without destruction of the original structure of the sediment layer at four sites of the lake. The concentration of DGT-labile P in the sediments, ranging from 0.007 to 0.206 mg L(-1), was highly heterogeneous across the profiles. The values of apparent diffusion flux (Fd) and release flux (Fr) of P varied between -0.027-0.197 mg m(-2) d(-1) and 0.037-0.332 mg m(-2) d(-1), respectively. Labile P showed a high and positive correlation (p < 0.01) with labile Fe(II) in the profiles, providing high-resolution evidence for the key role of Fe-redox cycling in labile P variation in sediments.

  14. Single bouts of exercise affect albumin redox state and carbonyl groups on plasma protein of trained men in a workload-dependent manner.

    PubMed

    Lamprecht, Manfred; Greilberger, Joachim F; Schwaberger, Guenther; Hofmann, Peter; Oettl, Karl

    2008-06-01

    The purpose of this study was to investigate the effect of single bouts of exercise at three different intensities on the redox state of human serum albumin (HSA) and on carbonyl groups on protein (CP) concentrations in plasma. Trained men [n = 44, maximal oxygen consumption (Vo(2max)): 55 +/- 5 ml.kg(-1).min(-1), nonsmokers, 34 +/- 5 years of age] from a homogenous population, volunteers from a police special forces unit, were randomly assigned to perform on a cycle ergometer either at 70% (n = 14), 75% (n = 14), or 80% (n = 16) of Vo(2max) for 40 min. Blood was collected before exercise, immediately after the exercise test (IE), and 30 min after each test (30M) and 30 h after each test (30H). The reduced fraction of HSA, human mercaptalbumin (HMA), decreased at all three exercise intensities IE and 30M, returning to preexercise values by 30H (P < 0.05). HMA was primarily oxidized to its reversible fraction human nonmercaptalbumin 1 (HNA1). CP concentrations increased at 75% of Vo(2max) IE and 30M with a tendency (P < 0.1) and at 80% Vo(2max) IE and 30M significantly, returning to preexercise concentrations by 30H (P < 0.01). These results indicate that the HSA redox system in plasma is activated after a single bout of cycle ergometer exercise at 70% Vo(2max) and 40 min duration. The extent of the HSA modification increased with exercise intensity. Oxidative protein damage, as indicated by CP, was only significantly increased at 80% Vo(2max) intensity in this homogenous cohort of trained men.

  15. Glutathione redox state, tocochromanols, fatty acids, antioxidant enzymes and protein carbonylation in sunflower seed embryos associated with after-ripening and ageing

    PubMed Central

    Morscher, F.; Kranner, I.; Arc, E.; Bailly, C.; Roach, T.

    2015-01-01

    Background and Aims Loss of seed viability has been associated with deteriorative processes that are partly caused by oxidative damage. The breaking of dormancy, a seed trait that prevents germination in unfavourable seasons, has also been associated with oxidative processes. It is neither clear how much overlap exists between these mechanisms nor is the specific roles played by oxygen and reactive oxygen species. Methods Antioxidant profiles were studied in fresh (dormant) or after-ripened (non-dormant) sunflower (Helianthus annuus) embryos subjected to controlled deterioration at 40 °C and 75 % relative humidity under ambient (21 %) or high O2 (75 %). Changes in seed vigour and viability, dormancy, protein carbonylation and fatty acid composition were also studied. Key Results After-ripening of embryonic axes was accompanied by a shift in the thiol-based cellular redox environment towards more oxidizing conditions. Controlled deterioration under high O2 led to a faster loss of seed dormancy and significant decreases in glutathione reductase and glutathione peroxidase activities, but viability was lost at the same rate as under ambient O2. Irrespective of O2 concentration, the overall thiol-based cellular redox state increased significantly over 21 d of controlled deterioration to strongly oxidizing conditions and then plateaued, while viability continued to decrease. Viability loss was accompanied by a rapid decrease in glucose-6-phosphate-dehydrogenase, which provides NADPH for reductive processes such as required by glutathione reductase. Protein carbonylation, a marker of protein oxidation, increased strongly in deteriorating seeds. The lipid-soluble tocochromanols, dominated by α-tocopherol, and fatty acid profiles remained stable. Conclusions After-ripening, dormancy-breaking during ageing and viability loss appeared to be associated with oxidative changes of the cytosolic environment and proteins in the embryonic axis rather than the lipid

  16. The desert gerbil Psammomys obesus as a model for metformin-sensitive nutritional type 2 diabetes to protect hepatocellular metabolic damage: Impact of mitochondrial redox state

    PubMed Central

    Gouaref, Inès; Detaille, Dominique; Wiernsperger, Nicolas; Khan, Naim Akhtar; Leverve, Xavier; Koceir, Elhadj-Ahmed

    2017-01-01

    Introduction While metformin (MET) is the most widely prescribed antidiabetic drug worldwide, its beneficial effects in Psammomys obesus (P. obesus), a rodent model that mimics most of the metabolic features of human diabetes, have not been explored thoroughly. Here, we sought to investigate whether MET might improve insulin sensitivity, glucose homeostasis, lipid profile as well as cellular redox and energy balance in P. obesus maintained on a high energy diet (HED). Materials and methods P. obesus gerbils were randomly assigned to receive either a natural diet (ND) consisting of halophytic plants (control group) or a HED (diabetic group) for a period of 24 weeks. MET (50 mg/kg per os) was administered in both animal groups after 12 weeks of feeding, i.e., the time required for the manifestation of insulin resistance in P. obesus fed a HED. Parallel in vitro experiments were conducted on isolated hepatocytes that were shortly incubated (30 min) with MET and energetic substrates (lactate + pyruvate or alanine, in the presence of octanoate). Results In vivo, MET lowered glycemia, glycosylated haemoglobin, circulating insulin and fatty acid levels in diabetic P. obesus. It also largely reversed HED-induced hepatic lipid alterations. In vitro, MET increased glycolysis but decreased both gluconeogenesis and ketogenesis in the presence of glucogenic precursors and medium-chain fatty acid. Importantly, these changes were associated with an increase in cytosolic and mitochondrial redox states along with a decline in respiration capacity. Conclusions MET prevents the progression of insulin resistance in diabetes-prone P. obesus, possibly through a tight control of gluconeogenesis and fatty acid β-oxidation depending upon mitochondrial function. While the latter is increasingly becoming a therapeutic issue in diabetes, the gut microbiota is another promising target that would need to be considered as well. PMID:28222147

  17. Redox signaling in acute pancreatitis

    PubMed Central

    Pérez, Salvador; Pereda, Javier; Sabater, Luis; Sastre, Juan

    2015-01-01

    Acute pancreatitis is an inflammatory process of the pancreatic gland that eventually may lead to a severe systemic inflammatory response. A key event in pancreatic damage is the intracellular activation of NF-κB and zymogens, involving also calcium, cathepsins, pH disorders, autophagy, and cell death, particularly necrosis. This review focuses on the new role of redox signaling in acute pancreatitis. Oxidative stress and redox status are involved in the onset of acute pancreatitis and also in the development of the systemic inflammatory response, being glutathione depletion, xanthine oxidase activation, and thiol oxidation in proteins critical features of the disease in the pancreas. On the other hand, the release of extracellular hemoglobin into the circulation from the ascitic fluid in severe necrotizing pancreatitis enhances lipid peroxidation in plasma and the inflammatory infiltrate into the lung and up-regulates the HIF–VEGF pathway, contributing to the systemic inflammatory response. Therefore, redox signaling and oxidative stress contribute to the local and systemic inflammatory response during acute pancreatitis. PMID:25778551

  18. Redox signaling in acute pancreatitis.

    PubMed

    Pérez, Salvador; Pereda, Javier; Sabater, Luis; Sastre, Juan

    2015-08-01

    Acute pancreatitis is an inflammatory process of the pancreatic gland that eventually may lead to a severe systemic inflammatory response. A key event in pancreatic damage is the intracellular activation of NF-κB and zymogens, involving also calcium, cathepsins, pH disorders, autophagy, and cell death, particularly necrosis. This review focuses on the new role of redox signaling in acute pancreatitis. Oxidative stress and redox status are involved in the onset of acute pancreatitis and also in the development of the systemic inflammatory response, being glutathione depletion, xanthine oxidase activation, and thiol oxidation in proteins critical features of the disease in the pancreas. On the other hand, the release of extracellular hemoglobin into the circulation from the ascitic fluid in severe necrotizing pancreatitis enhances lipid peroxidation in plasma and the inflammatory infiltrate into the lung and up-regulates the HIF-VEGF pathway, contributing to the systemic inflammatory response. Therefore, redox signaling and oxidative stress contribute to the local and systemic inflammatory response during acute pancreatitis. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  19. Protonation state of the Cu4S2 CuZ site in nitrous oxide reductase: redox dependence and insight into reactivity

    PubMed Central

    Johnston, Esther M.; Dell’Acqua, Simone; Pauleta, Sofia R.; Moura, Isabel; Solomon, Edward I.

    2015-01-01

    Spectroscopic and computational methods have been used to determine the protonation state of the edge sulfur ligand in the Cu4S2 CuZ form of the active site of nitrous oxide reductase (N2OR) in its 3CuICuII (1-hole) and 2CuI2CuII (2-hole) redox states. The EPR, absorption, and MCD spectra of 1-hole CuZ indicate that the unpaired spin in this site is evenly delocalized over CuI, CuII, and CuIV. 1-hole CuZ is shown to have a μ2-thiolate edge ligand from the observation of S-H bending modes in the resonance Raman spectrum at 450 and 492 cm−1 that have significant deuterium isotope shifts (−137 cm−1) and are not perturbed up to pH 10. 2-hole CuZ is characterized with absorption and resonance Raman spectroscopies as having two Cu-S stretching vibrations that profile differently. DFT models of the 1-hole and 2-hole CuZ sites are correlated to these spectroscopic features to determine that 2-hole CuZ has a μ2-sulfide edge ligand at neutral pH. The slow two electron (+1 proton) reduction of N2O by 1-hole CuZ is discussed and the possibility of a reaction between 2-hole CuZ and O2 is considered. PMID:26417423

  20. In situ X-ray near-edge absorption spectroscopy investigation of the state of charge of all-vanadium redox flow batteries.

    PubMed

    Jia, Chuankun; Liu, Qi; Sun, Cheng-Jun; Yang, Fan; Ren, Yang; Heald, Steve M; Liu, Yadong; Li, Zhe-Fei; Lu, Wenquan; Xie, Jian

    2014-10-22

    Synchrotron-based in situ X-ray near-edge absorption spectroscopy (XANES) has been used to study the valence state evolution of the vanadium ion for both the catholyte and anolyte in all-vanadium redox flow batteries (VRB) under realistic cycling conditions. The results indicate that, when using the widely used charge-discharge profile during the first charge process (charging the VRB cell to 1.65 V under a constant current mode), the vanadium ion valence did not reach V(V) in the catholyte and did not reach V(II) in the anolyte. Consequently, the state of charge (SOC) for the VRB cell was only 82%, far below the desired 100% SOC. Thus, such incompletely charged mix electrolytes results in not only wasting the electrolytes but also decreasing the cell performance in the following cycles. On the basis of our study, we proposed a new charge-discharge profile (first charged at a constant current mode up to 1.65 V and then continuously charged at a constant voltage mode until the capacity was close to the theoretical value) for the first charge process that achieved 100% SOC after the initial charge process. Utilizing this new charge-discharge profile, the theoretical charge capacity and the full utilization of electrolytes has been achieved, thus having a significant impact on the cost reduction of the electrolytes in VRB.

  1. Effects of low-pressure igneous processes and subduction on Fe3+/ΣFe and redox state of mantle eclogites from Lace (Kaapvaal craton)

    NASA Astrophysics Data System (ADS)

    Aulbach, S.; Woodland, A. B.; Vasilyev, P.; Galvez, M. E.; Viljoen, K. S.

    2017-09-01

    Reconstructing the redox state of the mantle is critical in discussing the evolution of atmospheric composition through time. Kimberlite-borne mantle eclogite xenoliths, commonly interpreted as representing former oceanic crust, may record the chemical and physical state of Archaean and Proterozoic convecting mantle sources that generated their magmatic protoliths. However, their message is generally obscured by a range of primary (igneous differentiation) and secondary processes (seawater alteration, metamorphism, metasomatism). Here, we report the Fe3+/ΣFe ratio and δ18 O in garnet from in a suite of well-characterised mantle eclogite and pyroxenite xenoliths hosted in the Lace kimberlite (Kaapvaal craton), which originated as ca. 3 Ga-old ocean floor. Fe3+/ΣFe in garnet (0.01 to 0.063, median 0.02; n = 16) shows a negative correlation with jadeite content in clinopyroxene, suggesting increased partitioning of Fe3+ into clinopyroxene in the presence of monovalent cations with which it can form coupled substitutions. Jadeite-corrected Fe3+/ΣFe in garnet shows a broad negative trend with Eu*, consistent with incompatible behaviour of Fe3+ during olivine-plagioclase accumulation in the protoliths. This trend is partially obscured by increasing Fe3+ partitioning into garnet along a conductive cratonic geotherm. In contrast, NMORB-normalised Nd/Yb - a proxy of partial melt loss from subducting oceanic crust (<1) and metasomatism by LREE-enriched liquids (>1) - shows no obvious correlation with Fe3+/ΣFe, nor does garnet δ18OVSMOW (5.14 to 6.21‰) point to significant seawater alteration. Median bulk-rock Fe3+/ΣFe is roughly estimated at 0.025. This observation agrees with V/Sc systematics, which collectively point to a reduced Archaean convecting mantle source to the igneous protoliths of these eclogites compared to the modern MORB source. Oxygen fugacites (fO2) relative to the fayalite-magnetite-quartz buffer (FMQ) range from Δlog ⁡ fO2 = FMQ-1.3 to FMQ-4

  2. Cell-cell and intracellular lactate shuttles.

    PubMed

    Brooks, George A

    2009-12-01

    Once thought to be the consequence of oxygen lack in contracting skeletal muscle, the glycolytic product lactate is formed and utilized continuously in diverse cells under fully aerobic conditions. 'Cell-cell' and 'intracellular lactate shuttle' concepts describe the roles of lactate in delivery of oxidative and gluconeogenic substrates as well as in cell signalling. Examples of the cell-cell shuttles include lactate exchanges between between white-glycolytic and red-oxidative fibres within a working muscle bed, and between working skeletal muscle and heart, brain, liver and kidneys. Examples of intracellular lactate shuttles include lactate uptake by mitochondria and pyruvate for lactate exchange in peroxisomes. Lactate for pyruvate exchanges affect cell redox state, and by itself lactate is a ROS generator. In vivo, lactate is a preferred substrate and high blood lactate levels down-regulate the use of glucose and free fatty acids (FFA). As well, lactate binding may affect metabolic regulation, for instance binding to G-protein receptors in adipocytes inhibiting lipolysis, and thus decreasing plasma FFA availability. In vitro lactate accumulation upregulates expression of MCT1 and genes coding for other components of the mitochondrial reticulum in skeletal muscle. The mitochondrial reticulum in muscle and mitochondrial networks in other aerobic tissues function to establish concentration and proton gradients necessary for cells with high mitochondrial densities to oxidize lactate. The presence of lactate shuttles gives rise to the realization that glycolytic and oxidative pathways should be viewed as linked, as opposed to alternative, processes, because lactate, the product of one pathway, is the substrate for the other.

  3. Cell–cell and intracellular lactate shuttles

    PubMed Central

    Brooks, George A

    2009-01-01

    Once thought to be the consequence of oxygen lack in contracting skeletal muscle, the glycolytic product lactate is formed and utilized continuously in diverse cells under fully aerobic conditions. ‘Cell–cell’ and ‘intracellular lactate shuttle’ concepts describe the roles of lactate in delivery of oxidative and gluconeogenic substrates as well as in cell signalling. Examples of the cell–cell shuttles include lactate exchanges between between white-glycolytic and red-oxidative fibres within a working muscle bed, and between working skeletal muscle and heart, brain, liver and kidneys. Examples of intracellular lactate shuttles include lactate uptake by mitochondria and pyruvate for lactate exchange in peroxisomes. Lactate for pyruvate exchanges affect cell redox state, and by itself lactate is a ROS generator. In vivo, lactate is a preferred substrate and high blood lactate levels down-regulate the use of glucose and free fatty acids (FFA). As well, lactate binding may affect metabolic regulation, for instance binding to G-protein receptors in adipocytes inhibiting lipolysis, and thus decreasing plasma FFA availability. In vitro lactate accumulation upregulates expression of MCT1 and genes coding for other components of the mitochondrial reticulum in skeletal muscle. The mitochondrial reticulum in muscle and mitochondrial networks in other aerobic tissues function to establish concentration and proton gradients necessary for cells with high mitochondrial densities to oxidize lactate. The presence of lactate shuttles gives rise to the realization that glycolytic and oxidative pathways should be viewed as linked, as opposed to alternative, processes, because lactate, the product of one pathway, is the substrate for the other. PMID:19805739

  4. Implications of phosphorus redox geochemistry

    NASA Astrophysics Data System (ADS)

    Pasek, Matthew

    2015-04-01

    Phosphorus is the limiting nutrient in many environments. Until recently, redox changes to phosphorus speciation have been confined to the realm of chemical laboratories as phosphorus was considered to be synonymous with phosphate in the natural environment. The few known phosphorus species with a reduced redox state, such as phosphine gas, were considered novelties. Recent work has revealed a surprising role for low redox state organophosphorus compounds -- the phosphonates -- in biogeochemistry. Additionally, phosphite and hypophosphite (the lower oxyanions of phosphorus) have been identified from natural sources, and microbial genomics suggests these compounds may be ubiquitous in nature. Recent work from our laboratory suggests that reduced phosphorus compounds such as phosphite and hypophosphite may be ubiquitous (Pasek et al. 2014). If so, then these species maybe important in the global phosphorus biogeochemical cycle, and could influence global phosphorus sustainability. Additionally, these compounds could have been relevant on the early earth environment, priming the earth with reactive phosphorus for prebiotic chemistry. Reference: Pasek, M. A., Sampson, J. M., & Atlas, Z. (2014). Redox chemistry in the phosphorus biogeochemical cycle. Proceedings of the National Academy of Sciences, 111(43), 15468-15473.

  5. Real time Measurement of Metabolic States in Living Cells using Genetically-encoded NADH Sensors

    PubMed Central

    Zhao, Yuzheng; Yang, Yi; Loscalzo, Joseph

    2014-01-01

    Redox metabolism plays critical roles in multiple biological processes and diseases. Until recently, knowledge of specific, key redox processes in living systems was limited by the lack of adequate methodology. Reduced nicotinamide adenine dinucleotide (NADH) and its oxidized form (NAD+) is the most important small molecule in the redox metabolism of mammalian cells. We previously reported a series of genetically encoded fluorescent sensors for intracellular NADH detection. Here, we present an accounting of experimental components and considerations, such as protein expression and purification, fluorescence titration, transfections, and confocal imaging, necessary to perform a standardized NADH assay experiment with these probes. In addition, we outline initial experiments used to derive basic principles of NADH/NAD+ redox biology in vitro. Finally, we describe a protocol for a steady-state kinetics experiment, and the processing of experimental data to measure intracellular NADH levels. PMID:24862275

  6. Electron Pathways through Erythrocyte Plasma Membrane in Human Physiology and Pathology: Potential Redox Biomarker?

    PubMed

    Matteucci, Elena; Giampietro, Ottavio

    2007-09-17

    Erythrocytes are involved in the transport of oxygen and carbon dioxide in the body. Since pH is the influential factor in the Bohr-Haldane effect, pHi is actively maintained via secondary active transports Na(+)/H(+) exchange and HC(3) (-)/Cl(-) anion exchanger. Because of the redox properties of the iron, hemoglobin generates reactive oxygen species and thus, the human erythrocyte is constantly exposed to oxidative damage. Although the adult erythrocyte lacks protein synthesis and cannot restore damaged proteins, it is equipped with high activity of protective enzymes. Redox changes in the cell initiate various signalling pathways. Plasma membrane oxido-reductases (PMORs) are transmembrane electron transport systems that have been found in the membranes of all cells and have been extensively characterized in the human erythrocyte. Erythrocyte PMORs transfer reducing equivalents from intracellular reductants to extracellular oxidants, thus their most important role seems to be to enable the cell respond to changes in intra- and extra-cellular redox environments.So far the activity of erythrocyte PMORs in disease states has not been systematically investigated. This review summarizes present knowledge on erythrocyte electron transfer activity in humans (health, type 1 diabetes, diabetic nephropathy, and chronic uremia) and hypothesizes an integrated model of the functional organization of erythrocyte plasma membrane where electron pathways work in parallel with transport metabolons to maintain redox homeostasis.

  7. The effect of Walterinnesia aegyptia venom proteins on TCA cycle activity and mitochondrial NAD(+)-redox state in cultured human fibroblasts.

    PubMed

    Ghneim, Hazem K; Al-Sheikh, Yazeed A; Aboul-Soud, Mourad A M

    2015-01-01

    Fibroblast cultures were used to study the effects of crude Walterinnesia aegyptia venom and its F1-F7 protein fractions on TCA cycle enzyme activities and mitochondrial NAD-redox state. Confluent cells were incubated with 10 μg of venom proteins for 4 hours at 37°C. The activities of all studied TCA enzymes and the non-TCA mitochondrial NADP(+)-dependent isocitrate dehydrogenase underwent significant reductions of similar magnitude (50-60% of control activity) upon incubation of cells with the crude venom and fractions F4, F5, and F7 and 60-70% for fractions F3 and F6. In addition, the crude and fractions F3-F7 venom proteins caused a drop in mitochondrial NAD(+) and NADP(+) levels equivalent to around 25% of control values. Whereas the crude and fractions F4, F5, and F7 venom proteins caused similar magnitude drops in NADH and NADPH (around 55% of control levels), fractions F3 and F6 caused a more drastic drop (60-70% of control levels) of both reduced coenzymes. Results indicate that the effects of venom proteins could be directed at the mitochondrial level and/or the rates of NAD(+) and NADP(+) biosynthesis.

  8. Administration of a leptin antagonist during the neonatal leptin surge induces alterations in the redox and inflammatory state in peripubertal /adolescent rats.

    PubMed

    Mela, Virginia; Hernandez, Oskarina; Hunsche, Caroline; Diaz, Francisca; Chowen, Julie A; De la Fuente, Mónica

    2017-10-15

    The importance of the neonatal leptin surge in rodents in neurodevelopmental processes has aroused curiosity in its implication in other physiological systems. Given the role of leptin in neuro-immune interactions, we hypothesized that the neonatal leptin surge could have an effect on the oxidative and inflammatory stress situations of both systems. We blocked the neonatal leptin surge by a leptin antagonist and measured several parameters of oxidative and inflammatory stress in the spleen, hypothalamus and adipose tissue of peripubertal/adolescent rats. The treated rats showed lower activity of several antioxidant enzymes in the spleen and their leukocytes released lower levels of mitogen-stimulated IL-10 and IL-13 and higher levels of TNF-alpha. In conclusion, the neonatal leptin surge may have a key role in the establishment of adequate redox and inflammatory states in the immune system, which is important for the generation of adequate immune responses and to obtain and maintain good health. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Malarial infection of female BWF1 lupus mice alters the redox state in kidney and liver tissues and confers protection against lupus nephritis.