Reactive Oxygen Species Distribution Research Articles

Elucidating Electrocatalytic Oxygen Reduction Kinetics via Intermediates by Time-Dependent Electrochemiluminescence.

Facile evaluation of oxygen reduction reaction (ORR) kinetics for electrocatalysts is critical for sustainable fuel-cell development and industrial H2 O2 production. Despite great success in ORR studies using mainstream strategies, such as the membrane electrode assembly, rotation electrodes, and advanced surface-sensitive spectroscopy, the time and spatial distribution of reactive oxygen species (ROS) intermediates in the diffusion layer remain unknown. Using time-dependent electrochemiluminescence (Td-ECL), we report an intermediate-oriented method for ORR kinetics analysis. Owing to multiple ultrasensitive stoichiometric reactions between ROS and the ECL emitter, except for electron transfer numbers and rate constants, the potential-dependent time and spatial distribution of ROS were successfully obtained for the first time. Such exclusively uncovered information would guide the development of electrocatalysts for fuel cells and H2 O2 production with maximized activity and durability.

Elucidating Electrocatalytic Oxygen Reduction Kinetics via Intermediates by Time‐Dependent Electrochemiluminescence

AbstractFacile evaluation of oxygen reduction reaction (ORR) kinetics for electrocatalysts is critical for sustainable fuel‐cell development and industrial H2O2 production. Despite great success in ORR studies using mainstream strategies, such as the membrane electrode assembly, rotation electrodes, and advanced surface‐sensitive spectroscopy, the time and spatial distribution of reactive oxygen species (ROS) intermediates in the diffusion layer remain unknown. Using time‐dependent electrochemiluminescence (Td‐ECL), we report an intermediate‐oriented method for ORR kinetics analysis. Owing to multiple ultrasensitive stoichiometric reactions between ROS and the ECL emitter, except for electron transfer numbers and rate constants, the potential‐dependent time and spatial distribution of ROS were successfully obtained for the first time. Such exclusively uncovered information would guide the development of electrocatalysts for fuel cells and H2O2 production with maximized activity and durability.

Applications of Antioxidants in Dental Procedures.

As people are paying more and more attention to dental health, various dental treatment procedures have emerged, such as tooth bleaching, dental implants, and dental restorations. However, a large number of free radicals are typically produced during the dental procedures. When the imbalance in distribution of reactive oxygen species (ROS) is induced, oxidative stress coupled with oxidative damage occurs. Oral inflammations such as those in periodontitis and pulpitis are also unavoidable. Therefore, the applications of exogenous antioxidants in oral environment have been proposed. In this article, the origin of ROS during dental procedures, the types of antioxidants, and their working mechanisms are reviewed. Additionally, antioxidants delivery in the complicated dental procedures and their feasibility for clinical applications are also covered. Finally, the importance of safety assessment of these materials and future work to take the challenge in antioxidants development are proposed for perspective.

Atomic-Layered Cu5 Nanoclusters on FeS2 with Dual Catalytic Sites for Efficient and Selective H2 O2 Activation.

Regulating the distribution of reactive oxygen species generated from H2 O2 activation is the prerequisite to ensuring the efficient and safe use of H2 O2 in the chemistry and life science fields. Herein, we demonstrate that constructing a dual Cu-Fe site through the self-assembly of single-atomic-layered Cu5 nanoclusters onto a FeS2 surface achieves selective H2 O2 activation with high efficiency. Unlike its unitary Cu or Fe counterpart, the dual Cu-Fe sites residing at the perimeter zone of the Cu5 /FeS2 interface facilitate H2 O2 adsorption and barrierless decomposition into ⋅OH via forming a bridging Cu-O-O-Fe complex. The robust in situ formation of ⋅OH governed by this atomic-layered catalyst enables the effective oxidation of several refractory toxic pollutants across a broad pH range, including alachlor, sulfadimidine, p-nitrobenzoic acid, p-chlorophenol, p-chloronitrobenzene. This work highlights the concept of building a dual catalytic site in manipulating selective H2 O2 activation on the surface molecular level towards efficient environmental control and beyond.

Atomic‐Layered Cu5 Nanoclusters on FeS2 with Dual Catalytic Sites for Efficient and Selective H2O2 Activation

AbstractRegulating the distribution of reactive oxygen species generated from H2O2 activation is the prerequisite to ensuring the efficient and safe use of H2O2 in the chemistry and life science fields. Herein, we demonstrate that constructing a dual Cu−Fe site through the self‐assembly of single‐atomic‐layered Cu5 nanoclusters onto a FeS2 surface achieves selective H2O2 activation with high efficiency. Unlike its unitary Cu or Fe counterpart, the dual Cu−Fe sites residing at the perimeter zone of the Cu5/FeS2 interface facilitate H2O2 adsorption and barrierless decomposition into ⋅OH via forming a bridging Cu‐O‐O‐Fe complex. The robust in situ formation of ⋅OH governed by this atomic‐layered catalyst enables the effective oxidation of several refractory toxic pollutants across a broad pH range, including alachlor, sulfadimidine, p‐nitrobenzoic acid, p‐chlorophenol, p‐chloronitrobenzene. This work highlights the concept of building a dual catalytic site in manipulating selective H2O2 activation on the surface molecular level towards efficient environmental control and beyond.

Let's shape again: the concerted molecular action that builds the pollen tube.

The pollen tube is being subjected to control by a complex network of communication that regulates its shape and the misfunction of a single component causes specific deformations. In flowering plants, the pollen tube is a tubular extension of the pollen grain required for successful sexual reproduction. Indeed, maintaining the unique shape of the pollen tube is essential for the pollen tube to approach the embryo sac. Many processes and molecules (such as GTPase activity, phosphoinositides, Ca2+ gradient, distribution of reactive oxygen species and nitric oxide, nonuniform pH values, organization of the cytoskeleton, balance between exocytosis and endocytosis, and cell wall structure) play key and coordinated roles in maintaining the cylindrical shape of pollen tubes. In addition, the above factors must also interact with each other so that the cell shape is maintained while the pollen tube follows chemical signals in the pistil that guide it to the embryo sac. Any intrinsic changes (such as erroneous signals) or extrinsic changes (such as environmental stresses) can affect the above factors and thus fertilization by altering the tube morphology. In this review, the processes and molecules that enable the development and maintenance of the unique shape of pollen tubes in angiosperms are presented emphasizing their interaction with specific tube shape. Thus, the purpose of the review is to investigate whether specific deformations in pollen tubes can help us to better understand the mechanism underlying pollen tube shape.

κ Opioid Receptor Agonist Inhibits Myocardial Injury in Heart Failure Rats through Activating Nrf2/HO-1 Pathway and Regulating Ca2+-SERCA2a.

Objectives We aimed to observe the protective effect of κ opioid receptor (κ-OR) agonist on myocardial injury in heart failure (HF) rats and its effect on Ca2+-SERCA2a and to explore the regulatory mechanism with the Nrf2/HO-1 signaling pathway. Methods 50 Sprague-Dawley rats were randomly divided into the following groups: the sham operation group (sham group), HF model group (HF group), HF+κ-OR agonist U50488 group (HU group), HF+U50488H+novel calmodulin-dependent protein kinase II (CaMKII) agonist (oleic acid) (HUO group), and HF+U50488H+Nrf2 inhibitor (HUM group). The HF rat's model was established through surgical ligation of the left anterior descending coronary artery and the exhausting swimming exercise. After that, rat's cardiac function was monitored by echocardiography. HE and MASSON staining was used to detect the myocardial injury, and TUNEL staining was used to detect the myocardial apoptosis. ELISA was performed to detect the biomarkers of oxidative stress. Moreover, the distribution of reactive oxygen species (ROS) and Nrf2 was detected under immunofluorescence. The expression of sarco/endoplasmic reticulum calcium (Ca2+) ATPase (SERCA) 2a, calmodulin, endoplasmic reticulum stress- (ERS-) related proteins, and Nrf2/HO-1 signaling pathway-related proteins were detected by Western Blotting. Results κ-OR agonist U50488H can significantly enhance rat's cardiac function, reduce the injury and apoptosis of myocardial cells, and alleviate endoplasmic reticulum stress injury in HF rats via upregulating the SERCA2a expression and inhibiting the Ca2+ influx. Furthermore, U50488H could also inhibit the phosphorylation of CaMKII and cAMP-response element binding protein (CREB). Additionally, administration of CaMKII-specific agonist could partially block the therapeutic effect of κ-OR agonist on the myocardium of HF rats. Interestingly, the antagonist of Nrf2 could also significantly reverse the therapeutic effect of κ-OR agonist. Therefore, these results suggested that the effect of U50488H on HF rats is dependent on regulating CaMKII phosphorylation and activating the Nrf2/HO-1 pathway. Conclusion κ-OR agonists U50488H can improve ERS in cardiomyocytes and relieve myocardial injury in HF rats through activating the Nrf2/HO-1 pathway and regulating Ca2+-SERCA2a to inhibit Ca2+ influx.

Influence of Retrogradation on KI–Starch Visualization of Reactive Oxygen Species Emitted by Plasma Jets

Plasma jets have been widely researched in the fields of medicine, biology, and agriculture and their positive effects were reported. To understand the working mechanism of plasma-target interaction, the spatial distribution of reactive oxygen species (ROS) at the target's surface should be examined as they are considered to be the most affectable factor to treat the target. The authors have used KI-starch method in the form of gel or liquid, which uses reactions among potassium iodide, starch, water, and oxidative species, to visualize the distribution of ROS. This method gives information regarding the distribution of ROS by coloration; however, the retrogradation of starch possibly influences on the visualization especially in a liquid KI-starch reagent. In this article, the visualization on the distribution of ROS was done via the liquid KI-starch reagent during plasma jets' irradiation with different helium gas flow rates from 1 to 4 L/min. The retrogradation of starch was confirmed when the gas flow rate was higher than 3 L/min, because the reagent's surface was cooled down, which incapacitated the ability of coloration from the reagent. It was revealed that a ring-like coloration pattern could be observed at the gas flow rate of 3 L/min, because the coloration occurred at the outside of an uncolored circular region where the retrogradation of starch was formed by the gas flow and insensitive to ROS.

Raman-tag labelled Au@ZIF-8 for cell metabolism monitoring in vitro.

Cell metabolism decides the state of cells in division, differentiation and growth, maintaining intracellular balance. Monitoring the metabolic behavior of cells is of great significance to study the development of diseases in cell levels. Surface-enhanced Raman spectroscopy (SERS) is a powerful technique to detect and quantify analytes in extremely low concentration. Combined with SRES technology, we can monitor the concentration of metabolites in live cells and thus study the biological behavior of cells. In this work, Raman-tag labelled Au@ZIF-8 nanoparticles were used to monitor the distribution of reactive oxygen species (ROS) in SKOV3 cells. With the help of the ultrasensitive Raman enhancement material, the distribution of ROS in SKOV3 cells was mapped, the results were further confirmed in the fluorescent images. The SERS platform provides an ultrasensitive monitoring method of ROS distribution, which may offer an opportunity for real-time monitoring the cell metabolism in the cell biology applications.

Tomato SlIDA has a critical role in tomato fertilization by modifying reactive oxygen species homeostasis.

Anther development and pollen tube elongation are key steps for pollination and fertilization. The timing and spatial distribution of reactive oxygen species (ROS) and programmed cell death are central to these processes, but the regulatory mechanism of ROS production is not well understood. Inflorescence deficient in abscission (IDA) is implicated in many plant development and responses to environmental stimuli. However, their role in reproductive development is still unknown. We generated tomato knockout lines (CR-slida) of an IDA homolog (SlIDA), which is expressed in the tapetum, septum and pollen tube, and observed a severe defect in male gametes. Further analysis indicated that there was a programmed cell death defect in the tapetum and septum and a failure of anther dehiscence in the CR-slida lines, likely related to insufficient ROS signal. Liquid chromatography-tandem mass spectrometry identified mature SlIDA as a 14-mer EPIP peptide, which was shown to be secreted, and a complementation experiment showed that application of a synthetic 14-mer EPIP peptide rescued the CR-slida defect and enhanced the ROS signal. Moreover, the application of the ROS scavengers diphenyleneiodonium or Mn-TMPP suppressed peptide function. Collectively, our results revealed that SlIDA plays an essential role in pollen development and pollen tube elongation by modulating ROS homeostasis.

Study of Modified Area of Polymer Samples Exposed to a He Atmospheric Pressure Plasma Jet Using Different Treatment Conditions.

In the last decade atmospheric pressure plasma jets (APPJs) have been routinely employed for surface processing of polymers due to their capability of generating very reactive chemistry at near-ambient temperature conditions. Usually, the plasma jet modification effect spans over a limited area (typically a few cm²), therefore, for industrial applications, where treatment of large and irregular surfaces is needed, jet and/or sample manipulations are required. More specifically, for treating hollow objects, like pipes and containers, the plasma jet must be introduced inside of them. In this case, a normal jet incidence to treated surface is difficult if not impossible to maintain. In this paper, a plasma jet produced at the end of a long flexible plastic tube was used to treat polyethylene terephthalate (PET) samples with different incidence angles and using different process parameters. Decreasing the angle formed between the plasma plume and the substrate leads to increase in the modified area as detected by surface wettability analysis. The same trend was confirmed by the distribution of reactive oxygen species (ROS), expanding on starch-iodine-agar plates, where a greater area was covered when the APPJ was tilted. Additionally, UV-VUV irradiation profiles obtained from the plasma jet spreading on the surface confirms such behavior.

Visualization of Plasma-Induced Liquid Flow Using KI–Starch and PIV

The application of plasma jet interacting gel or liquid targets is widely researched and positive effects are obtained in biological experiments. To understand the working mechanism of plasma jet, the measurement of the spatial distribution of reactive oxygen species (ROS) is necessary. The authors have used potassium iodide (KI)–starch method, which uses reactions among KI, starch, and oxidative species, to visualize the distribution of ROS. Although our purpose focused on the 2-D distribution of ROS on the surfaces of liquid and agar regents, unexpected plasma-induced flow was also observed along the depth direction of the KI–starch liquid reagent. In this article, the plasma-induced flow generated by plasma jet was visualized with KI–starch, floating particle, and particle image velocimetry (PIV) methods, and the obtained results among the three observations were compared. The plasma-induced flow visualized by iodide–starch complexes in KI–starch method was similar to the flow of tracer particles in floating particle method. According to the analysis of PIV measurement, the velocity of the downstream was about 8 mm/s.

RGF1 controls root meristem size through ROS signalling.

Stem cell niche and root meristem size are maintained by intercellular interactions and signaling networks of a peptide hormone, Root Meristem Growth Factor 1 (RGF1). How RGF1 regulates root meristem development is an essential question to understand stem cell function. Although five receptors of RGF1 have been identified, the downstream signaling mechanism remains unknown. Here, we report a series of signaling events following RGF1 action. The RGF1-receptor pathway controls the distribution of reactive oxygen species (ROS) along the developmental zones of the Arabidopsis root. We identify a novel transcription factor, RGF1 INDUCIBLE TRANSCRIPTION FACTOR 1 (RITF1) that plays a central role in mediating RGF1 signaling. Manipulating RITF1 expression leads to redistribution of ROS along the root developmental zones. Changes in ROS distribution, in turn, enhance the stability of the PLETHORA2 (PLT2) protein, a master regulator of root stem cells. Our study, thus, clearly depicts a signaling cascade initiated by RGF1, linking the RGF1 peptide to ROS regulatory mechanisms.

The Role of Signaling Pathways of Inflammation and Oxidative Stress in Development of Senescence and Aging Phenotypes in Cardiovascular Disease.

The ASK1-signalosome→p38 MAPK and SAPK/JNK signaling networks promote senescence (in vitro) and aging (in vivo, animal models and human cohorts) in response to oxidative stress and inflammation. These networks contribute to the promotion of age-associated cardiovascular diseases of oxidative stress and inflammation. Furthermore, their inhibition delays the onset of these cardiovascular diseases as well as senescence and aging. In this review we focus on whether the (a) ASK1-signalosome, a major center of distribution of reactive oxygen species (ROS)-mediated stress signals, plays a role in the promotion of cardiovascular diseases of oxidative stress and inflammation; (b) The ASK1-signalosome links ROS signals generated by dysfunctional mitochondrial electron transport chain complexes to the p38 MAPK stress response pathway; (c) the pathway contributes to the sensitivity and vulnerability of aged tissues to diseases of oxidative stress; and (d) the importance of inhibitors of these pathways to the development of cardioprotection and pharmaceutical interventions. We propose that the ASK1-signalosome regulates the progression of cardiovascular diseases. The resultant attenuation of the physiological characteristics of cardiomyopathies and aging by inhibition of the ASK1-signalosome network lends support to this conclusion. Importantly the ROS-mediated activation of the ASK1-signalosome p38 MAPK pathway suggests it is a major center of dissemination of the ROS signals that promote senescence, aging and cardiovascular diseases. Pharmacological intervention is, therefore, feasible through the continued identification of potent, non-toxic small molecule inhibitors of either ASK1 or p38 MAPK activity. This is a fruitful future approach to the attenuation of physiological aspects of mammalian cardiomyopathies and aging.

Comparative Proteomic Analysis Provides Insights into the Regulatory Mechanisms of Wheat Primary Root Growth

Plant roots are vital for acquiring nutrients and water from soil. However, the mechanisms regulating root growth in hexaploid wheat remain to be elucidated. Here, an integrated comparative proteome study on the roots of two varieties and their descendants with contrasting root phenotypes was performed. A total of 80 differentially expressed proteins (DEPs) associated with the regulation of primary root growth were identified, including two plant steroid biosynthesis related proteins and nine class III peroxidases. Real-time PCR analysis showed that brassinosteroid (BR) biosynthesis pathway was significantly elevated in long-root plants compared with those short-root plants. Moreover, O2.− and H2O2 were distributed abundantly in both the root meristematic and elongation zones of long root plants, but only in the meristematic zone of short-root plants. The differential distribution of reactive oxygen species (ROS) in the root tips of different genotypes may be caused by the differential expression of peroxidases. Taken together, our results suggest that the regulation of wheat primary root growth is closely related to BR biosynthesis pathway and BR-mediated ROS distribution.

Shielding‐gas‐controlled atmospheric pressure plasma jets: Optical emission, reactive oxygen species, and the effect on cancer cells

Shielding‐gas‐controlled helium atmospheric pressure plasma jets (APPJs) in contact with conductive or nonconductive liquid are investigated. Two‐dimensional (2D) optical emission intensity maps of plasma species directly above the liquid, the 2D distribution of reactive oxygen species (ROS) on the liquid surface, and the 2D distribution of DNA double‐strand breaks (DSBs) induced in epithelial cancer cells are provided. When conductive liquid is used, the plasma jet develops a glow‐discharge‐like structure at the liquid surface. The ROS distribution is found to be strongly dependent on both the shielding gas composition and the liquid conductivity. The amount of DNA DSBs is found to be largest when using N2 shielding gas and almost negligible when using O2 shielding gas.

The Deubiquitinase OTU5 Regulates Root Responses to Phosphate Starvation.

Phosphorus, taken up by plants as inorganic phosphate (Pi), is an essential but often growth-limiting mineral nutrient for plants. As part of an orchestrated response to improve its acquisition, insufficient Pi supply triggers alterations in root architecture and epidermal cell morphogenesis. Arabidopsis (Arabidopsis thaliana) mutants defective in the expression of the OVARIAN TUMOR DOMAIN-CONTAINING DEUBIQUITINATING ENZYME5 (OTU5) exhibited a constitutive Pi deficiency root phenotype, comprising the formation of long and dense root hairs and attenuated primary root growth. Quantitative protein profiling of otu5 and wild-type roots using the isobaric tag for relative and absolute quantification methodology revealed genotype- and Pi-dependent alterations in protein profiles. In otu5 plants, Pi starvation caused a short-root-hair phenotype and decreased abundance of a suite of Pi-responsive root hair-related proteins. Mutant plants also showed the accumulation of proteins involved in chromatin remodeling and altered distribution of reactive oxygen species along the root, which may be causative for the alterations in root hair morphogenesis. The root hair phenotype of otu5 was synergistic to that of actin-related protein6 (arp6), harboring a mutation in the SWR1 chromatin-remodeling complex. Genetic analysis of otu5/arp6 double mutants suggests independent but functionally related roles of the two proteins in chromatin organization. The root hair phenotype of otu5 is not caused by a general up-regulation of the Pi starvation response, indicating that OTU5 acts downstream of or interacts with Pi signaling. It is concluded that OTU5 is involved in the interpretation of environmental information, probably by altering chromatin organization and maintaining redox homeostasis.

Effects of high fructose intake on the development of hypertension in the spontaneously hypertensive rats: the role of AT1R/gp91PHOX signaling in the rostral ventrolateral medulla

Both genetic and dietary factors determine the development of hypertension. Whether dietary factor impacts the development of hereditary hypertension is unknown. Here, we evaluated the effect of daily high-fructose diet (HFD) on the development of hypertension in adolescent spontaneously hypertensive rats (SHR). Six-week-old SHR were randomly divided into two groups to receive HFD or normal diet (ND) for 3 weeks. The temporal profile of systolic blood pressure, alongside the sympathetic vasomotor activity, in the SHR-HFD showed significantly greater increases at 9–12 weeks of age compared with the age-matched SHR-ND group. Immunofluorescence was used to identify the distribution of reactive oxygen species (ROS), oxidants and antioxidants in rostral ventrolateral medulla (RVLM) where sympathetic premotor neurons reside. In RVLM of SHR-HFD, the levels of ROS accumulation and lipid peroxidation were elevated. The changes in protein expression were measured by Western blot. NADPH oxidase subunit gp91phox and angiotensin II type I receptor were up-regulated in RVLM neuron. On the other hand, the expression of extracellular superoxide dismutase was suppressed. Both molecular and hemodynamic changes in the SHR-HFD were rescued by oral pioglitazone treatment from weeks 7 to 9. Furthermore, central infusion with tempol, a ROS scavenger, effectively ameliorated ROS accumulation in RVLM and diminished the heightened pressor response and enhanced sympathetic activity in the SHR-HFD. Together, these results suggest that HFD intake at adolescent SHR may impact the development of hypertension via increasing oxidative stress in RVLM which could be effectively attenuated by pioglitazone treatment.

Two-dimensional concentration distribution of reactive oxygen species transported through a tissue phantom by atmospheric-pressure plasma-jet irradiation

The two-dimensional concentration distribution of reactive oxygen species (ROSs) transported through an agarose-film tissue phantom by atmospheric-pressure plasma-jet irradiation is visualized using a KI-starch gel reagent. Oxygen addition to helium enhances ROS transportation through the film. A radial ROS distribution pattern at the plasma-irradiated film surface changes into a doughnut-shaped pattern after passing through the film. The ROS transportation speed is 0.14–0.2 mm/min. We suggest that there are two types of ROS transportation pathways in the plasma-irradiated film: linear and circular. The majority of ROSs are transported through the circular pathway. ROS concentration distributions changed markedly with irradiation distance. Diffusive ROS transportation due to a concentration gradient is negligible in plasma-irradiated films.

Atherosclerosis and Vascular Biology

Atherosclerosis and Vascular Biology