Increasing H2O2 Concentration Research Articles

Drought and exogenous abscisic acid alter hydrogen peroxide accumulation and differentially regulate the expression of two maize RD22-like genes

Increased biosynthesis of abscisic acid (ABA) occurs in plants in response to water deficit, which is mediated by changes in the levels of reactive oxygen species such as H2O2. Water deficit and ABA induce expression of some RD22-like proteins. This study aimed to evaluate the effect of water deficit and exogenous ABA (50 µM ABA applied every 24 hours for a total of 72 hours) on H2O2 content in Zea mays (maize) and to characterise genes encoding two putative maize RD22-like proteins (designated ZmRD22A and ZmRD22B). The expression profiles of the two putative maize RD22-like genes in response to water deficit and treatment with ABA were examined in leaves. In silico analyses showed that the maize RD22-like proteins share domain organisation with previously characterized RD22-like proteins. Both water deficit and exogenous ABA resulted in increased H2O2 content in leaves but the increase was more pronounced in response to water deficit than to exogenous ABA. Lignin content was not affected by exogenous ABA, whereas it was decreased by water deficit. Expression of both RD22-like genes was up-regulated by drought but the ZmRD22A gene was not influenced by exogenous ABA, whereas ZmRD22B was highly responsive to exogenous ABA.

Reactive radical-driven bacterial inactivation by hydrogen-peroxide-enhanced plasma-activated-water

The combined effects of plasma activated water (PAW) and hydrogen peroxide (H2O2), PAW/HP, in sterilization were investigated in this study. To assess the synergistic effects of PAW/HP, S. aureus was selected as the test microorganism to determine the inactivation efficacy. Also, the DNA/RNA and proteins released by the bacterial suspensions under different conditions were examined to confirm membrane integrity. Additionally, the intracellular pH (pHi) of S. aureus was measured in our study. Electron spin resonance spectroscopy (ESR) was employed to identify the presence of radicals. Finally, the oxidation reduction potential (ORP), conductivity and pH were measured. Our results revealed that the inactivation efficacy of PAW/HP is much greater than that of PAW, while increased H2O2 concentration result in higher inactivation potential. More importantly, as compared with PAW, the much stronger intensity ESR signals and higher ORP in PAW/HP suggests that the inactivation mechanism of the synergistic effects of PAW/HP: more reactive oxygen species (ROS) and reactive nitrogen species (RNS), especially OH and NO radicals, are generated in PAW combined with H2O2 resulting in more deaths of the bacteria.

Role of phenolic compounds during antioxidative responses of winter triticale to aphid and beetle attack

One of the earliest responses of plants to insects’ attack is generation of reactive oxygen species. However, the elevated level of ROS can elicit oxidative burst within plant tissues, and plants employ antioxidant systems against these radicals. Due to their chemical structures, polyphenols are able to diminish the level of ROS. Thus, we investigated the role of phenolic compounds in oxidative stress within winter triticale caused by Sitobion avenae and Oulema melanopus. It was found, that infestation by insects induced a high increase in the content of hydrogen peroxide and superoxide anion radical within resistant Lamberto cv. 24 hpi, whereas in sensitive Marko cv., an increase in H2O2 content was found within two days of aphid feeding. Moreover, resistant plants showed earlier and much greater induction of l-phenylalanine and l-tyrosine ammonia lyases and chalcone synthase activities, as well as accumulation of phenolic compounds in response to insect feeding than susceptible Marko. On the other hand, strong positive influence of hydrogen peroxide and superoxide radical contents on chalcone synthase activity and furthermore flavonoid biosynthesis was detected in the susceptible cultivar. Negative relationships between level of o-coumaric acid or flavonoid compounds and content of hydrogen peroxide or superoxide radical suggest their antioxidant capacity. Luteolin and o-coumaric acid may attend in scavenging of hydrogen peroxide, whereas quercetin, apigenin and (+)-catechin probably participate in reduction of superoxide anion radical content.

Antioxidant responses under jasmonic acid elicitation comprise enhanced production of flavonoids and anthocyanins in Jatropha curcas leaves

Jatropha curcas has significant potential for production of biodiesel and secondary metabolites with medical applications. The effect of jasmonic acid (JA) on flavonoid production and antioxidant responses in two Mexican J. curcas plants (accessions I-64 and I-52), growing under controlled environmental conditions, was studied. Foliar application of JA (0.25, 0.5, and 1.0 mM) increased flavonoid content by 3.3-fold (445.6 ± 62.2 µg QE g−1 DW) at 1.0 mM in the I-64 accession after 120 h. At this time, individual flavonoid levels of kaempferol, apigenin, and vitexin were 6.8 (106.8 ± 18.6 µg g−1 DW), 4.4 (15.5 ± 1.5 µg g−1 DW), and 8.1 (6.27 ± 1.3 µg g−1 DW) times higher than in the controls, while for the I-52 specimens, the highest increase of flavonoids occurred at 24 h. In treated I-52 plants, enhancement of 58% (74.7 ± 9.2 µg g−1 DW) in anthocyanins occurred after 120 h, while in I-64 plants, they remained similar to controls. Phenylalanine ammonia lyase showed a peak of activity after 120 h in treated I-64 plants, while the I-52 accession showed peaks at 24 and 120 h. Elicited I-64 plants presented H2O2 levels similar to controls with a 30.6% increase in catalase (CAT) and 3.3-fold in ascorbate peroxidase (APX) activities. In elicited I-52 plants, a 2.4-fold increase in H2O2 concentration was related to a 65.6% decrease of CAT and a 1.8-fold increase of APX activities. Therefore, under JA elicitation, J. curcas plants increased antioxidant responses including flavonoid and anthocyanin production to maintain cell redox balance.

Silicon amendment is involved in the induction of plant defense responses to a phloem feeder

Plant resistance to herbivores is a key component in integrated pest management. In most cases, silicon (Si) amendment to plants enhances resistance to herbivorous insects. The increase of plant physical barrier and altered insect behaviors are proposed as mechanisms for the enhanced resistance in Si-amended plants, but our understanding of the induced mechanisms involved in Si-enhanced plant resistance to phloem-feeding insects remains unclear. Here, we show that Si amendment to rice (Oryza sativa) plants impacts multiple plant defense responses induced by a phloem-feeder, the brown planthopper (Nilaparvata lugens, BPH). Si amendment improved silicification of leaf sheaths that BPH feed on. Si addition suppressed the increase of malondialdehyde concentration while encouraged increase of H2O2 concentration in plants attacked by BPH. Higher activities of catalase and superoxide dismutase were recorded in Si-amended than in non-amended BPH-infested plants. BPH infestation activated synthases for secondary metabolites, polyphenol oxidase and pheny-lalanine ammonia-lyase, and β-1,3-glucanase, but the activation was greater in Si-amended than in non-amended plants. Taken together, our findings demonstrate that Si amendment interacts with BPH infestation in the induction of plant defense responses and consequently, to confer enhanced rice plant resistance.

Nitrogen Metabolism in Adaptation of Photosynthesis to Water Stress in Rice Grown under Different Nitrogen Levels.

To investigate the role of nitrogen (N) metabolism in the adaptation of photosynthesis to water stress in rice, a hydroponic experiment supplying with low N (0.72 mM), moderate N (2.86 mM), and high N (7.15 mM) followed by 150 g⋅L-1 PEG-6000 induced water stress was conducted in a rainout shelter. Water stress induced stomatal limitation to photosynthesis at low N, but no significant effect was observed at moderate and high N. Non-photochemical quenching was higher at moderate and high N. In contrast, relative excessive energy at PSII level (EXC) was declined with increasing N level. Malondialdehyde and hydrogen peroxide (H2O2) contents were in parallel with EXC. Water stress decreased catalase and ascorbate peroxidase activities at low N, resulting in increased H2O2 content and severer membrane lipid peroxidation; whereas the activities of antioxidative enzymes were increased at high N. In accordance with photosynthetic rate and antioxidative enzymes, water stress decreased the activities of key enzymes involving in N metabolism such as glutamate synthase and glutamate dehydrogenase, and photorespiratory key enzyme glycolate oxidase at low N. Concurrently, water stress increased nitrate content significantly at low N, but decreased nitrate content at moderate and high N. Contrary to nitrate, water stress increased proline content at moderate and high N. Our results suggest that N metabolism appears to be associated with the tolerance of photosynthesis to water stress in rice via affecting CO2 diffusion, antioxidant capacity, and osmotic adjustment.

Synthesis and electropolymerization of EDOT modified 1,3-bis(5-methyl-2-thiazolylimino)isoindolinato palladium(II) complex for electrochemical detection of hydrogen peroxide

1,3-Bis(5-methyl-2-thiazolylimino) isoindoline derivative (EDOT-BTI) containing an electropolymerizable group is prepared using the Linstead method. According to this two-step method phthalonitrile derivative EDOT-Pht is converted to 1,3-diiminoisoindoline EDOT-DII first then EDOT-DII is reacted with 2-amino-5-methylthiazole in ethanol during 5 day reflux. Palladium(II) complex (EDOT-PdBTI) of EDOT-BTI is synthesized in benzene using [Pd(PhCN)2Cl2] as the palladium(II) precursor and triethylamine as auxiliary base. In order to show the H2O2 sensing properties of EDOT-PdBTI, electrochemical characterizations of EDOT-BTI and EDOT-PdBTI are performed and then modified glassy carbon electrode is constructed with electropolymerization of EDOT-PdBTI. GCE/PEDOT-PdBTI shows a wave at 0.215 V. With increasing H2O2 concentration, this wave shifts to −0.075 V. A linear range is observed between 0.72 and 13.6 μmol dm−3 with a limit of detection of 0.21 μmoldm−3 and sensitivity of 0.0153 mV μmol−1 dm−3. These data illustrate possible use of the electrode as a potentiometric H2O2 sensor.

Morphology-controlled synthesis of Ni-B nanoparticles by addition of hydrogen peroxide

In this paper, H2O2 was used to control the morphology of Ni-B nanoparticles prepared by chemical reduction of nickel ethylenediamine complex. With increasing H2O2 concentration, Ni-B nanoparticle morphology progressed from pompon-like to sea urchin-like and finally to a flower-like shape. The controlled morphology was the result of dynamic equilibrium between the reduction of nickel ions by KBH4 and oxidation dissolution of Ni-B nanoparticles due to etching by H2O2. Additionally, the Ni-B catalyst nanoparticles had large BET areas and more uniform Ni active centers on the surface. However, excess H2O2 could disrupt the dynamic equilibrium, allowing the production of various structures of Ni-B nanoparticles. The catalyst composition with a molar ratio of 1:1 Ni ion to H2O2 showed the best activity toward electrocatalytic oxidation of ethanol.

A similar local immune and oxidative stress phenotype in vitiligo and halo nevus

BackgroundVitiligo and halo nevus are two common T-cell-mediated skin disorders. Although autoimmunity has been suggested to be involved in both diseases, the relationship between vitiligo and halo nevus is not fully understood. ObjectiveThe aim of the current study was to investigate whether vitiligo and halo nevus share the same immunological and oxidative stress response. MethodsInfiltrations of T cells, and expressions of chemokine receptors (CXCR3, CCR4, CCR5) and cytotoxic markers (Granzyme B, Perforin) in the lesions of vitiligo and halo nevus were examined by immunohistochemistry. Enzyme-linked immunosorbent assay was performed to analyze the expressions of chemokines in the serum samples and cytotoxic markers secreted by CD8+ T cells which were sorted from the peripheral blood mononuclear cells in healthy donors, vitiligo and halo nevus patients. Tissue levels of chemokine receptors and CXCR3 ligands in healthy controls, vitiligo patients and halo nevus patients were determined by qRT-PCR analysis. The percentages of CXCR3+ CD4+ T and CXCR3+ CD8+ T cells from the peripheral blood samples were examined by flow cytometry. Tissue and serum hydrogen peroxide (H2O2) concentrations were measured using H2O2 assay kit. ResultsImmunohistochemistry revealed a significant T-cell response, with pronounced dermal infiltrates of CD8+ T cells in vitiligo and halo nevus. The inflammatory cytotoxic markers such as Granzyme B and Perforin were also elevated in vitiligo and halo nevus, suggesting inflammatory responses in situ. By qRT-PCR and ELISA assay, we found significantly increased expressions of the chemokine receptor CXCR3 and its ligands, especially the accumulated CXCL10 in the skin lesions of vitiligo and halo nevus. Moreover, the level of H2O2, a key player involved in regulation of the immune response was significantly upregulated in the skin lesions of vitiligo and halo nevus. In addition, the increased H2O2 concentration correlated positively with CXCL10 level in skin lesions of vitiligo and halo nevus. ConclusionsThese results demonstrate a H2O2-involved autoimmune phenotype in vitiligo and halo nevus, characterized by increased level of IFN-γ-inducible chemokine pair CXCL10-CXCR3, as well as a dense CD8+ T infiltration in the skin lesions, thus suggesting a similar pathogenesis of the two diseases.

Accelerated ageing and subsequent imbibition affect seed viability and the efficiency of antioxidant system in macaw palm seeds

Accelerated ageing is an accurate test indicator of seed vigor and storability that helps to understand the mechanisms of cellular and biochemical deterioration that occur during seed ageing. This study was carried out to elucidate the mechanisms of ageing in macaw palm embryos. Seeds were artificially aged during 4, 8 and 12 days at 45 °C and 100% relative humidity. After ageing, seeds were tested for viability (tetrazolium), electrical conductivity, lipid peroxidation (MDA) and hydrogen peroxide (H2O2) content. Part of the aged seeds was imbibed for 8 days and then determined the hydrogen peroxide content and the activity of antioxidant system enzymes (superoxide dismutase, catalase and glutathione reductase). Ageing reduced the embryo viability from 8 days of treatment and increased malondialdehyde content (MDA) and solute leakage. Hence, membrane permeability correlated with both loss of viability and lipid peroxidation. Imbibition after ageing significantly increased H2O2 content along with superoxide dismutase activity. Catalase activity was significantly higher than control in embryos aged from 8 days and imbibed, and glutathione reductase activity did not change. Our results suggest that macaw palm seed deterioration during accelerated ageing is closely related to lipid peroxidation, and that enzymatic antioxidant system is not completely efficient in reducing reactive oxygen species after imbibition, a critical phase to germination. Moreover, accelerated ageing test can be used as a reliable model to understand the mechanisms involved in palm seeds deterioration.

The effect of simulated inflammatory conditions and Fenton chemistry on the electrochemistry of CoCrMo alloy.

Inflamed conditions may develop in total joint replacement applications and may impact on the corrosion of metallic biomaterials like CoCrMo alloy. The influence of simulated inflammatory (SI) conditions on the corrosion behavior of CoCrMo alloy was investigated. A range of SI solutions, based on phosphate buffered saline with H2 O2 , HCl, and Fe3+ additions, were investigated. Open circuit potential (OCP), corrosion currents and impedance of the oxide film surface were all significantly (p < 0.05) affected by increases in H2 O2 concentration and decrease of pH. OCP (vs. Ag/AgCl) increased from -0.250 V in PBS solution to 0.355 V and 0.650 V in 30 mM H2 O2 at pH 7.4 and pH 1 PBS solution. Iron ions (0.1 mM) in PBS solutions with 10 mM H2 O2 (Fenton chemistry) increased OCP to 0.6 V. Icorr increased from 0.2 µA/cm2 to 14 µA/cm2 in SI conditions. Electrochemical impedance spectroscopy showed decreased in oxide resistance (Rox , p < 0.05) while capacitance (CPE) increased (p < 0.05) in SI solutions, pH 7.4 (Rox = 5 × 103 Ω cm2 , CPE = 55 µF/cm2 ) as well as in Fenton reagent solution (Rox = 3.2 × 104 Ω cm2 , CPE = 45 µF/cm2 ) compared to PBS only (Rox = 5 × 105 Ω cm2 , CPE = 31 µF/cm2 ). These results indicate the corrosion susceptibility of CoCrMo alloy can be significantly increased by SI solutions, increasing the oxidizing power and decreasing the passivity of the oxide film. Cell-released chemicals such as H2 O2 and acid are able to facilitate the corrosion of CoCrMo alloy and demonstrate part of the mechanism of inflammatory cell induced corrosion. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 209-220, 2018.

Molecular characterization of GhPLDα1 and its relationship with secondary cell wall thickening in cotton fibers.

Phospholipase D (PLD) hydrolyzes phospholipids to generate a free polar head group (e.g., choline) and a second messenger phosphatidic acid and plays diverse roles in plant growth and development, including seed germination, leaf senescence, root hair growth, and hypocotyl elongation. However, the function of PLD in cotton remains largely unexplored. Here, the comprehensive molecular characterization of GhPLDα1 was explored with its role in upland cotton (Gossypium hirsutum) fiber development. The GhPLDα1 gene was cloned successfully, and a sequence alignment showed that GhPLDα1 contains one C2 domain and two HKD (HxKxxxxD) domains. Quantitative reverse transcriptase-polymerase chain reaction measured the expression of GhPLDα1 in various cotton tissues with the highest level in fibers at 20 days post anthesis (d.p.a.). Fluorescent microscopy and immunoblotting in tobacco epidermis showed the GhPLDα1 distribution in both cell membranes and the cytoplasm. An activity assay indicated changes in PLDα enzyme activity in developing fiber cells with a peak level at 20 d.p.a., coinciding with the onset of cellulose accumulation and the increased H2O2 content during fiber development. Furthermore, the inhibition of PLDα activity obviously decreased the cellulose and H2O2 contents of in vitro-cultured cotton fibers. These results provide important evidence explaining the relationship of GhPLDα1 with secondary cell wall thickening in cotton fibers in that GhPLDα1 may correlate with the increased H2O2 content at the onset of secondary cell wall thickening, ultimately promoting cellulose biosynthesis.

Stimulation effect of carrageenan on enzymatic defense system of sweet basil against Cuscuta campestris infection

ABSTRACTSweet basil is an important medicinal plant used especially for therapeutical potentials. Sweet basil is a common host for Cuscuta campestris, which has a negative effect on infected plants. Therefore, natural friendly control of C. campestris seems to be useful. It has been shown that carrageenans can act as elicitors of plant defense responses. In this work, the effect of κ-carrageenans on protection against C. campestris and suppression of its invasion in basils were studied. Basils were sprayed with a solution of κ-carrageenan (1 g L−1), once a week, three times in total. Infection of basils with C. campestris was performed two days after the last carrageenan treatment. C. campestris stem and the leaves of basils were collected two weeks after C. campestris inoculation for biochemical studies. Treatment with carrageenan significantly increased shoot length and leaf area of basil and decreased C. campestris infestation by about 26%. The content of malondialdehyde, other aldehydes, hydrogen peroxide and lipoxygenase (LOX) activity increased significantly in basils parasitized by C. campestris. There were significant differences in phenylalanine ammonia lyase (PAL), catalase (CAT), superoxide dismutase (SOD) and peroxidase activity of parasitized basils by C. campestris compared with healthy basils. Carrageenan treatment of basils caused a significant increase in H2O2 content and the activity of PAL, CAT and SOD, but not of malondialdehyde, other aldehydes content and LOX, polyphenol oxidase (PPO) and peroxidases activity. The activated enzymatic defense system (PAL, PPO, CAT, SOD and peroxidase) in carrageenan-treated basils have a vital role in alleviating oxidative stress damage in infected plants, by removing excess reactive oxygen species and inhibiting LOX activity and lipid peroxidation that was observed in this study. Our results showed that the application of κ-carrageenan-induced beneficial effects in plants, with regard to growth stimulation and the activation of enzymatic defense system. Thus, carrageenan was recommended as a natural biostimulator for protection of plants against C. campestris.

H2O2-Loaded Acoustic Phase-Change Nanoparticles Ehancing Coronary Micro-Circulation Thrombolysis: An in Vitro Study by Low Intensity Focused Ultrasound Irradiation

Thrombolysis and oxygen (O2) supply in coronary micro-circulation are crucial for the treatment of acute myocardial infarction (AMI). The biochemical reaction synergized as cavitation effect of perfluoropentane (PFP) nanoparticles has the potential of targeted thrombolysis by ultrasound irradiation while H2O2 in the hydrogen peroxide solution provides O2 in coronary micro-embolization. Therefore, we sought to explore the clinical implication of hydrogen peroxide solution with PFP loaded nanoparticles to develop a novel plan for the treatment of coronary micro- embolization. Artery thrombosis was collected by carotid artery injury and stasis in 10 rabbits. H2O2/PFP nanoparticles (group A) were experimented in an in-vitro vascular system with Low Intensity Focused Ultrasound (LIFU) irradiation, comparing with PFP nanoparticles only (group B) and PBS buffer solution as control (group C). Group A, B and C circulated into the system where the thrombosis was placed in the middle. Thrombolysis ratios and pathological slides were analyzed. Dissolved Oxygen Detector (DOD) inspected the volume of O2 in the vascular system after LIFU exposure. The mean diameter and charge of the nanoparticles were (432.7± 26.8) nm and (-43.87±3.12) mV respectively, which showed uniform size and regular shape under the microscope. When the nanoparticles sonicated by LIFU, they changed phase gradually and transformed into microbubbles (MB). The results showed the highest efficiency of thrombolysis when the irradiation power and time were 5 w, 15 min. The dissolution ratios in group A (42.18±7.4) % was significantly larger than those in group B (29.26±3.2) % and C (7.24±2.63) % (p＜0.05). The pathological changes showed that in group A, a significant decrease of red blood cell in the thrombus was observed, and the structure of platelet were disorganized. Compared with group A, there was still considerable amount of red blood cells inside the thrombus with compact structure of platelet trabeculae in group B and C. The DOD showed that along with the increase of H2O2 concentration, the amount of O2 release was rising. For the sake of biosecurity and efficiency, 5% H2O2 was engaged in the experiment which can release (12.2±0.79) mg/L O2. H2O2/PFP nanoparticles with LIFU performed thrombolysis and provided O2 in coronary micro-circulation, which may establish a novel non-invasive primary treatment protocol of AMI.

Improved photocatalytic removal of acid red 14 by amino-functionalized Fe3O4–WO3 nanoparticles from aqueous solutions in the presence of UV irradiation

The Fe3O4–WO3–3-aminopropyltriethoxysilane (APTES) nanoparticles were applied as a heterogeneous catalyst in the presence of UV irradiation for acid red 14 (AR14) removal. This nanocatalyst was synthesized via a facile co-precipitation method and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, vibrating sample magnetometer and point of zero charge techniques. The effects of some operating parameters such as solution pH, nanocatalyst dosage, initial AR14 concentration, H2O2 concentration, different purging gases and type of organic compounds on the removal efficiency were studied. Under optimal conditions: pH = 3, AR140 = 30 mg/L, nanocatalyst dosage = 0.2 g/L and H2O2 = 50 mM, 99.99% of the dye was removed after 120 min. As nanocatalyst dosage increased, the photocatalytic removal of AR14 enhanced up to the desired amount of 0.4 g/L. Moreover, the removal efficiency increased with increasing H2O2 concentration and in the presence of different purging gases. And, the photocatalytic removal of AR14 increased in the presence of oxalate, citric acid, phenol and Ethylenediaminetetraacetic acid, and decreased in the presence of folic acid and humic acid. Three kinetic models were developed for this process and the findings showed that the dye removal rate obeyed the first-order kinetic. Estimation of the EEO value for the UV/Fe3O4–WO3–APTES (288.88 kWh/m3) process, as a function of the removal efficiency, revealed that this process not only increased the efficiency, but also decreased the cost of electrical energy consumed by the system. Additionally, the photocatalytic activity was maintained even after five successive cycles. © 2017 Desalination Publications. All rights reserved.

The quantitative determination of hydrogen peroxide by voltammetry on the carbositall electrode

The electrochemical behaviour of hydrogen peroxide (H2O2) has been studied using the alternating current voltammetry with square wave modulation in the potential range of +1.0…–1.0 V on the carbositall electrode as a working and auxiliary electrode (vs Ag,AgCl/KCl(sat)). The peak was obtained at Ep = +0.16 V on the background of 0.1 Mol L–1 Na2SO4 and 0.01 Mol L–1 KHSO4 (pH≈2.4) with its height rising proportionally to the increase of H2O2 concentrations. The linear dependence was observed in the H2O2 concentration range of (1.7-10.2)×10–5 Mol L–1, the calibration curve equation was Ip = (8.6±0.7)×103с (r = 0.998); LOD = 6.16×10–6 Mol L–1, LOQ = 2.05×10–5 Mol L–1. To determine H2O2 in solutions of antiseptic drugs the standard addition method was used.

Changes in endogenous hormones and H2O2 burst during shoot organogenesis in TDZ-treated Saussurea involucrate explants

Thidiazuron [N-phenyl-N-(1, 2, 3-thidiazol-5-yl) urea, TDZ] treatment significantly improved shoot morphogenesis of Saussurea involucrata Kar. Et Kir (S. involucrata) leaf explants. The biochemical mechanisms underlying TDZ-induced shoot organogenesis were investigated by measuring endogenous plant growth hormones, H2O2, as well as the activities of superoxide dismutase (SOD) and catalase (CAT). The levels of endogenous gibberellic A3 (GA3) and zeatin (ZT) significantly increased in leaf explants subject to a 28-day treatment than the controls. However, extending exposure time to TDZ inhibited GA3 accumulation. At the same time, the SOD activity increased significantly until the 28th of TDZ treatment time and the CAT activity reduced simultaneously, which was closely linked with the significant increase in H2O2 concentrations in the explants. And there was a sharply promotion after the 35 day of culture time if the plant tissue was always in medium contained, which was in company with the cell activity decreased. We propose that a combination of increased GA3, ZT, and H2O2 concentration is the basis for the enhanced shoot morphogenesis in response to TDZ treatment. These results provide a starting point for an improved understanding of the biochemical mechanisms underlying TDZ-induced shoot organogenesis of S. involucrata.

Microwaves affect Myriophyllum aquaticum plants differently depending on the wave polarization

Previous studies on microwave exposure on plants have revealed variations in sensitivity of plants to different microwave frequencies, exposure durations, and power intensities. However, the effects of different polarizations of microwaves on plants have not been studied. Therefore, we investigated the effect of horizontally and vertically polarized 2 GHz continuous microwaves on Myriophyllum aquaticum plants at 1.8 W m-2 power density. The electric potential variation along the vascular tissues were investigated for 1.5 h and growth parameters, pigmentation, and H2O2 formation were studied during 48 h microwave exposure. Exposure to horizontally polarized microwaves, decreased standard deviation of electric potential variation and increased H2O2 content significantly. Vertically polarized microwaves increased the standard deviation of electric potential variation and photosynthetic pigments significantly. However, none of the polarizations altered growth parameters (shoot length, stem diameter, and internodal length). Thermographic images taken for 1 h continuous microwave exposure did not indicate alteration in the temperature of the plants for both vertical and horizontal polarities.

Epidermal hydrogen peroxide is not increased in lesional and non-lesional skin of vitiligo.

It is widely believed that the loss of the epidermal melanocytes in vitiligo is basically due to excessive oxidative stress. Previous research work described abnormal elevation of the absolute concentration of the epidermal hydrogen peroxide (H2O2) in lesional and non-lesional skin of vitiligo. Based on this finding, our primary research objective was to use this feature as a screening marker in individuals at a great risk of developing vitiligo. Ninety-six patients of non-segmental vitiligo (NSV) of varying durations, skin phototypes, and treatment modalities (psoralen UVA-, narrow band UVB-treated) were recruited for this study. Raman spectroscopic measurements, using an external probehead, of the lesional and non-lesional skin were obtained, and the resulting spectra were analyzed using the Opus software package of the MultiRam spectrometer and the intensity of the peak at 875cm-1 that represents the absolute concentration of H2O2 was calculated. Contrary to previous reports, in patients of skin phototype IV, the absolute concentrations of H2O2 in non-lesional and lesional NSV of all groups were non-significantly decreased compared to normal control. In patients of NSV of skin phototype V, the decrease in the absolute concentrations of H2O2 was not significant in the untreated group, and a slight non-significant increase in the NBUVB-treated group was noted. However, in the PUVA-treated group, the non-lesional skin demonstrated significant increase in the absolute concentration of H2O2, whereas the lesional skin showed only a slight non-significant increase compared to normal control. InNSV patients of skin phototype VI who were previously treated with PUVA, the non-lesional skin showed a slight non-significant increase in the absolute concentration of H2O2; however, the lesional skin showed a marked significant decrease compared to normal control and the non-lesional skin. Thereof, one can conclude that the epidermal H2O2 is not increased in NSV as previously thought and may not be responsible for the oxidative stress that leads to the melanocytes destruction, the hallmark of vitiligo pathogenesis.

Excess boron responsive regulations of antioxidative mechanism at physio-biochemical and molecular levels in Arabidopsis thaliana

This work was aimed to evaluate the effect of boron (B) toxicity on oxidative damage level, non-enzymatic antioxidant accumulation such as anthocyanin, flavonoid and proline and expression levels of antioxidant enzymes including superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) and glutathione reductase (GR) and their respective activities as well as expression levels of miR398 and miR408 in Arabidopsis thaliana. Plants were germinated and grown on MS medium containing 1 mM B (1B) and 3 mM B (3B) for 14 d. Toxic B led to a decrease of photosynthetic pigments and an increase in accumulation of total soluble and insoluble sugars in accordance with phenotypically viewed chlorosis of seedlings through increasing level of B concentration. Along with these inhibitions, a corresponding increase in contents of flavonoid, anthocyanin and proline occurred that provoked oxidative stress tolerance. 3B caused a remarkable increase in total SOD activity whereas the activities of APX, GR and CAT remained unchanged as verified by expected increase in H2O2 content. In contrast to GR, the coincidence was found between the expressions of SOD and APX genes and their respective activities. 1B induced mir398 expression, whereas 3B did not cause any significant change in expression of mir408 and mir398. Expression levels of GR genes were coordinately regulated with DHAR2 expression. Moreover, the changes in expression level of MDAR2 was in accordance with changes in APX6 expression and total APX activity, indicating fine-tuned regulation of ascorbate-glutathione cycle which might trigger antioxidative responses against B toxicity in Arabidopsis thaliana.