Increasing H2O2 Concentration Research Articles

Hydroxide Sludge/Hydrochar-Fe Composite Catalysts for Photo-Fenton Degradation of Dyes

The photo-Fenton oxidation process was employed to degrade methylene blue (MB) using a hydroxide sludge/hydrochar-Fe composite as a catalyst prepared by physical activation of raw hydroxide sludge from a drinking water treatment plant and hydrochar-Fe prepared by hydrothermal carbonization from two-phase olive mill waste. The prepared composite was characterized by XRD, SEM, EDS, ICP, and FT-IR. The effect of major parameters, including pH, H2O2 concentration, and a dose of composite on the removal of MB has been studied. The results indicated that the MB decolorization rate increased with the increase of H2O2 concentration and catalyst addition; however, further increase in H2O2 concentration and catalyst dosage could not result in an increase of MB removal efficiency. A high degradation of 95% was achieved within 150 min under UV light irradiation at natural pH (pH = 5), a catalyst loading of 2.5 g/L, a H2O2 dosage of 14.68 mol/L, and MB concentration of 50 mg/L. Recycling studies show a MB decolorization of 92% after three cycles and the use of the composite for the degradation of another dye (methyl orange) shows a degradation of 99%, demonstrating that this composite is a promising heterogeneous photo-Fenton catalyst for long-term removal of dyes from industrial wastewater.

Identification of GhLOG gene family revealed that GhLOG3 is involved in regulating salinity tolerance in cotton (Gossypium hirsutum L.)

Cytokinin (CK) is an important plant hormone that promotes plant cell division and differentiation, and participates in salt response under osmotic stress. LOGs (LONELY GUY) are CK-activating enzymes involved in CK synthesis. The LOG gene family has not been comprehensively characterized in cotton. In this study we identified 151 LOG genes from nine plant species, including 28 LOG genes in Gossypium hirsutum. Phylogenetic analysis divided LOG genes into three groups. Exon/intron structures and protein motifs of GhLOG genes were highly conserved. Synteny analysis revealed that several gene loci were highly conserved between the A and D sub-genomes of G. hirsutum with purifying selection pressure during evolution. Expression profiles showed that most LOG genes were constitutively expressed in eight different tissues. Furthermore, LOG genes can be regulated by abiotic stresses and phytohormone treatments. Moreover, subcellular localization revealed that GhLOG3_At resides inside the cell membrane. Overexpression of GhLOG3 enhanced salt tolerance in Arabidopsis. Virus-induced gene silencing (VIGS) of GhLOG3_At in cotton enhanced sensitivity of plants to salt stress with increased H2O2 contents and decreased chlorophyll and proline (PRO) activity. Our results suggested that GhLOG3_At induces salt stress tolerance in cotton, and provides a basis for the use of CK synthesis genes to regulate cotton growth and stress resistance.

Tumor Tissue Oxidative Stress Changes and Na, K-ATPase Evaluation in Head and Neck Squamous Cell Carcinoma.

Changes in metabolism are mechanisms that are largely implicated in the development, progression, and metastasis of head and neck squamous cell carcinoma (HNSCC) and also in resistance to different anticancer therapies. Identification of biomarkers for differentiation between cancerous and normal epithelium, treatment design and prognosis remain a vital issue in the field of head and neck cancer. The present study analyzed the main biochemical changes that occur in HNSCC tumors by through mechanisms involving oxidative stress. The release of substances reactive to thiobarbituric acid was significantly lower in HNSCC tumor tissue as compared to healthy tissue. The assays related to the lipid profile assays showed changes in membrane biophysics of tumor cells due to an increase in total phospholipids and total cholesterol, as well as an increased activity and expression of the α1 subunit of Na, K-ATPase, which is fundamental in the process of carcinogenesis. The modulation of the antioxidant system was also affected, with a decrease in the catalytic activity of the enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx), as well as a reduction of glutathione (GSH) content and an increase in H2O2 content. A reduction in catalase (CAT) activity was observed. The data presented here are in accordance with important findings described by us in a previous study, involving the same individuals, but with a focus on the damage generated in red blood cells, resulting from tumor installation. Therefore, it was possible to conclude that the biochemical alterations found in HNSCC cells are fundamental for transformation and maintenance of the tumor cell and once it is installed, it is also capable of generating injuries in the patients' red blood cells. Our data demonstrate that this could be a promising biomarker for HNSCC.

Candida Oleophila Proliferated and Accelerated Accumulation of Suberin Poly Phenolic and Lignin at Wound Sites of Potato Tubers.

Candida oleophila is a type of biocontrol yeast offering effective postharvest disease control. To the best of our knowledge, the effect of C. oleophila upon the healing of tubers is yet to be studied. The present study addresses the existing knowledge gap by investigating the effect of C. oleophila on wound healing in potato tubers. The results show that C. oleophila colonized and proliferated at the wound sites during the early and intermediate stages of healing. In addition, C. oleophila reduced weight loss of wounded tubers, decreased disease index of inoculated tubers with Fusarium sulphureum, and accelerated accumulation of suberin poly phenolic (SPP) and lignin at wound sites. C. oleophila activated phenylpropanoid metabolism and increased the content of SPP monomers, total phenol, flavonoids, and lignin. Furthermore, the yeast increased H2O2 content as well as peroxidase activity.

Physiological, Morphological and Antioxidant Responses of Pediococcus pentosaceus R1 and Lactobacillus fermentum R6 Isolated from Harbin Dry Sausages to Oxidative Stress.

As functional starter cultures and potential probiotics, the ability of lactic acid bacteria to resist oxidative stress is essential to maintain viability and functional properties. This study investigates the effects of H2O2 at different concentrations (0, 1, 2, and 3 mM) on the physiological, morphological, and antioxidant properties of Pediococcus pentosaceus R1 and Lactobacillus fermentum R6 isolated from Harbin dry sausages. The increase in H2O2 concentration induced a significant increase in reactive oxygen species and a decrease in intracellular ATP levels (p < 0.05). Based on scanning electron microscopy, transmission electron microscopy, and electric conductivity analysis, H2O2 stress caused cell deformation, the destruction of cell membrane integrity, partial loss of the cytoplasm, and an increase in the cell conductivity of both strains. H2O2 stress with 1 mM or 2 mM concentrations could effectively improve the scavenging rates of free radicals, the activities of superoxide dismutase and glutathione peroxide, and the total antioxidant capacity of both strains (p < 0.05). In conclusion, an appropriate oxidative stress contributed to the activation of the antioxidant defense system of both strains, conferred strains a better effect in inhibiting the oxidation of fermented foods, and improved the health of the host.

Iron Tetrasulfonatophthalocyanine-Catalyzed Starch Oxidation Using H2O2: Interplay between Catalyst Activity, Selectivity, and Stability.

Oxidized starch can be efficiently prepared using H2O2 as an oxidant and iron(III) tetrasulfophthalocyanine (FePcS) as a catalyst, with properties in the same range as those for commercial oxidized starches prepared using NaOCl. Herein, we performed an in-depth study on the oxidation of potato starch focusing on the mode of operation of this green catalytic system and its fate as the reaction progresses. At optimum batch reaction conditions (H2O2/FePcS molar ratio of 6000, 50 °C, and pH 10), a high product yield (91 wt %) was obtained with substantial degrees of substitution (DSCOOH of 1.4 and DSCO of 4.1 per 100 AGU) and significantly reduced viscosity (197 mPa·s) by dosing H2O2. Model compound studies showed limited activity of the catalyst for C6 oxidation, indicating that carboxylic acid incorporation likely results from C–C bond cleavage events. The influence of the process conditions on the stability of the FePcS catalyst was studied using UV–vis and Raman spectroscopic techniques, revealing that both increased H2O2 concentration and temperature promote the irreversible degradation of the FePcS catalyst at high pH. The rate and extent of FePcS degradation were found to strongly depend on the initial H2O2 concentration where also the rapid decomposition of H2O2 by FePcS occurs. These results explain why the slow addition of H2O2 in combination with low FePcS catalyst concentration is beneficial for the efficient application in starch oxidation.

β-Aminobutyric acid treatment accelerates the deposition of suberin polyphenolic and lignin at wound sites of potato tubers during healing

β-Aminobutyric acid (BABA) is a nonprotein amino acid that induces plant defense responses to numerous biotic and abiotic stresses. However, whether BABA treatment affects the wound healing process of potato tubers has yet to be reported. In this study, we examined the effects of BABA treatment on the weight loss and disease index of Solanum tuberosum L. cv. Atlantic potato tubers inoculated with Fusarium sulphureum and assessed the deposition of suberin polyphenolic (SPP) and lignin at the wound sites of these tubers during healing. We also investigated the indexes involved in phenylpropane metabolism, H2O2, and peroxidase in the underlying effect mechanism. BABA treatment effectively reduced the weight loss of wounded tubers (by 41.0 %) and the disease index of inoculated tubers (by 43.2 %) during healing (at 21 d and relative to the control). BABA treatment also accelerated the deposition of SPP and lignin at wound sites. SPP and lignin cell layers in the treated tubers were 58.45 % and 54.72 % thicker, respectively, than the equivalent cell layers in the controls at 7 d of healing. Additionally, BABA treatment significantly enhanced the activities of phenylalanine ammonia-lyase (PAL), 4-coumaryl coenzyme A ligase (4CL), cinnamic acid-4-hydroxylase (C4H), and cinnamyl alcohol dehydrogenase (CAD) while also promoting the synthesis of cinnamic acid, p-coumaric acid, caffeic acid, ferulic acid, sinapic acid, cinnamyl alcohol, coniferyl alcohol, and sinapyl alcohol, as well as increasing total phenolic and lignin content, at wound sites during healing. Furthermore, BABA treatment increased H2O2 content and peroxidase activity at the wounds. These results suggest that BABA treatment activates phenylpropanoid metabolism, increases H2O2 content and peroxidase activity, and accelerates the deposition of SPP and lignin in potato tuber wounds, all of which lead to reductions in the weight loss and disease index of tubers during healing.

Implications of hydrogen peroxide on bromate depression during seawater ozonation

The presence of hydrogen peroxide (H2O2) in ozonation process can resist the formation of carcinogenic bromate (BrO3¯) efficiently, and the bromate depression is closely related with background water qualities, especially in high bromide-containing seawater. In this study, the freshwater and seawater were selected to investigate the effects of H2O2 on ozone (O3) decomposition kinetics, bromide transformation and bromate depression, and the evolutions of BrO3¯ under different scavengers were explored to speculate the primary bromate formation pathways. The results showed that the initial O3 half-live period (t1/2-O3) in seawater was only one-sixth of that in freshwater, and its attenuation rate increased analogously with the increase of H2O2 concentration in both freshwater and seawater. The H2O2 could promote the formation of BrO3¯ via hydroxyl radical (•OH) based bromate pathways, nevertheless higher concentration of H2O2 facilitated the reduction of HOBr/OBr¯ back to Br¯, resulting in 87.0% and 73.2% of BrO3¯ retardment in freshwater and seawater, respectively. The suppression ratios of BrO3¯ were up to 48.4% and 35.3% in freshwater with the addition of •OH and •O2¯ scavengers, and the corresponding depressions in seawater decreased to 35.3% and 12.7%, indicating that •OH was dominant on bromate formation when the concentration of residual ozone was adequate to generate some bromine intermediates, meanwhile H2O2 and •O2¯ functioned as the key reductants for bromate depression. Based on these results, the Br¯ transformation mechanisms via O3, •OH, H2O2, and •O2¯ reactions were speculated, and the feasibility of H2O2-ozonation was verified for the treatment of high Br¯-containing seawater.

Salinity modulates lead (Pb) tolerance and phytoremediation potential of quinoa: a multivariate comparison of physiological and biochemical attributes.

Salinity and lead (Pb) contamination of soil are important environmental issues. A hydroponics experiment was performed to unravel the effects of salinity on modulation of Pb tolerance and phytoremediation potential of quinoa. Four-week-old plants of quinoa genotype "Puno" were treated with different concentrations of NaCl (0, 150 and 300mM), Pb (0, 250 and 500μM) and their combinations. It was noticed that plant biomass, chlorophyll contents and stomatal conductance of quinoa were slightly affected at 150mM NaCl or 250μM Pb. However, the higher concentrations of NaCl (300mM) and Pb (500μM) caused significant decline in these attributes. The accumulation of Na in quinoa increased under the combined application of salt with highest level of Pb. The uptake of K was not affected at the lower levels of either salinity or Pb, but decreased significantly at their highest levels. The combination of salinity and Pb increased H2O2 contents and caused lipid peroxidation that was mitigated by the activation of antioxidant enzymes (superoxide dismutase, catalase, peroxidase, ascorbate peroxidase). The activities of these enzymes increased by 4-, 3.75-, 5.4- and 2-fold, respectively, in the combined application of 500μM Pb and 300mM NaCl with respect to control. A multivariate analysis indicated that Pb tolerance potential of quinoa under combined application of NaCl and Pb was higher at 150 than 300mM NaCl. The bioconcentration factor and translocation factor for Pb remained less than one either in the absence or presence of salinity. Lead accumulation and tolerance potential indicated that quinoa genotype "Puno" is suitable for phytostabilization of Pb under saline conditions.

Drought stress-induced changes in redox metabolism of barley (Hordeum vulgare L.).

In the present investigation, influence of water stress on redox metabolism was evaluated in the flag leaf and grains of four barley (Hordeum vulgare L.) genotypes viz DWRB 101, 432 ICARDA, Jyoti and 430 ICARDA at 10th, 20th and 30th days after anthesis (DAA). Relative water content, electrolyte leakage, antioxidative enzymes and their related metabolites were studied during drought stress. Relative water content was well maintained in both the tissues of DWRB 101 and 432 ICARDA. The upregulation of catalase at 20th DAA while ascorbate peroxidase, glutathione reductase and dehydro reductase at 30th DAA in the flag leaf and grains of DWRB 101 and 432 ICARDA may be responsible for lesser increase in H2O2 content as compared to other genotypes. Moreover, the downregulation of superoxide dismutase was comparatively higher in Jyoti and 430 ICARDA. The redox homeostasis was well established during the stress in DWRB 101 and 432 ICARDA by maintaining comparatively higher ratios of ascorbate/dehydroascorbate and reduced/oxidized glutathione. Therefore, scrutiny of data indicated that DWRB 101 and 432 ICARDA may perform better under drought stress in comparison with Jyoti and 430 ICARDA.

A Novel Nonenzymatic Hydrogen Peroxide Sensor Based on Magnetic Core-Shell Fe3O4@C/Au Nanoparticle Nanocomposite.

Fe3O4@C/Au nanoparticle (AuNP) nanocomposites were prepared through electrostatic adsorption of AuNPs onto PDDA-functionalized core/shell Fe3O4@C magnetic nanospheres, which had been synthesized by a facile solvothermal method. The morphology and composition of the nanocomposites were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), etc. Moreover, highly electrocatalytic activity to the reduction of hydrogen peroxide (H2O2) was also exhibited on the Fe3O4@C/AuNP-modified indium tin oxide (ITO) electrode. The effect of solution pH and the modification amount of Fe3O4@C/AuNPs on the performance of electrocatalytic H2O2 reduction was investigated. Under the optimal conditions, the catalytic current showed a linear relationship with the increase of H2O2 concentration in the range of 0.007–15 mM and a detection limit of 5 μM. The H2O2 sensor showed high selectivity for H2O2 detection, which could effectively resist the interference of ascorbic acid (AA), uric acid (UA), and citric acid (CA). Finally, the H2O2 sensor was used in the real fetal bovine serum to detect H2O2 and obtained satisfactory results with the recovery values ranging from 95.14 to 103.6%.

Self-assembly prepared using an ion pair of poly(ethylene imine) and (phenylthio) acetic acid as a drug carrier for oxidation, temperature, and NIR-responsive release

Poly(ethylene imine)/(phenylthio) acetic acid (PEI/PTA) ion pair whose the molar ratio of amino to carboxyl group ratio was 3/7 exhibited its upper critical solution temperature (UCST) around body temperature (37 ℃) at pH 7.0. The UCST decreased with increasing H2O2 concentration used to treat the ion pair (0 to 20 mM). Below the UCST, PEI/PTA ion pair was self-assembled into nanoparticles (IPSAM) possibly because the ion pair was amphiphilic and surface-active. The ion pair decreased in the surface activity and increased in the critical micelle concentration, when the sulfide of PTA was oxidized by H2O2. This could account for why the UCST decreased with increasing H2O2 concentration. IPSAM released its payload (i.e. nile red) in response to oxidation and temperature. Upon oxidation, the ion pair decreased in its UCST and IPSAM underwent dissolution, leading to a promoted release. Upon heating, the temperature increased above UCST, which caused IPSAM to be disassembled and release its payload. Gold nanoparticle (GNP) synthesized in situ was found to be bound to IPSAM. IPSAM bearing GNP exhibited a promoted release of its payload under near-infrared (NIR) irradiation. Heat generated by GNP would be able to disassemble IPSAM and enhance the release. Doxorubicin loaded in folated IPSAM exhibited a significant in vitro anti-cancer activity against KB cells. It could be effectively internalized into the cells, evidenced by fluorescence-activated cell sorting analysis and confocal laser scanning microscopy. When GNP was included in IPSAM, NIR irradiation led to further increase in the anti-cancer activity.

Roles of calcium-dependent protein kinases mediated reactive oxygen species homeostasis in inducing resistance of apples by acibenzolar-S-methyl

This study was carried out to investigate the effect of acibenzolar-S-methyl (ASM) and ethylenebis (oxyethylenenitrilo) tetraacetic acid (EGTA) treatments on calcium-dependent protein kinases (CDPKs) and reactive oxygen species (ROS) metabolism in apples. Postharvest ASM treatment increased H2O2 content, reduced glutathione and ascorbic acid contents, and NADPH oxidase, peroxidase, ascorbate peroxidase, superoxide dismutase and glutathione reductase activities and retarded catalase activity and MdCAT expression in apples. ASM treatment enhanced MdSOD, MdPOD, MdAPX, MdGR, MdCDPK1, MdCDPK4, MdCDPK5, MdCDPK7, and MdCDPK21 expressions in apples. However, EGTA + ASM treatments suppressed H2O2, glutathione and ascorbic acid contents, NADPH oxidase, peroxidase, superoxide dismutase, ascorbate peroxidase and glutathione reductase activities. EGTA + ASM treatments suppressed the selected genes expressions in ROS metabolism and CDPKs, but up-regulated MdCAT expression in apples. These findings suggest that CDPKs play a vital role in regulating ROS metabolism and involve in inducing resistance in apples by ASM.

Nitric Oxide and Hydrogen Sulfide Coordinately Reduce Glucose Sensitivity and Decrease Oxidative Stress via Ascorbate-Glutathione Cycle in Heat-Stressed Wheat (Triticum aestivum L.) Plants.

The involvement of nitric oxide (NO) and hydrogen sulfide (H2S) in countermanding heat-inhibited photosynthetic features were studied in wheat (Triticum aestivum L.). Heat stress (HS) was employed at 40 °C after establishment for 6 h daily, and then plants were allowed to recover at 25 °C and grown for 30 days. Glucose (Glc) content increased under HS and repressed plant photosynthetic ability, but the application of sodium nitroprusside (SNP, as NO donor) either alone or with sodium hydrosulfide (NaHS, as H2S donor) reduced Glc-mediated photosynthetic suppression by enhancing ascorbate-glutathione (AsA-GSH) metabolism and antioxidant system, which reduced oxidative stress with decreased H2O2 and TBARS content. Oxidative stress reduction or inhibiting Glc repression was maximum with combined SNP and NaHS treatment, which was substantiated by 2-4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) and hypotaurine (HT), scavengers for NO and H2S, respectively. The scavenge of H2S reduced NO-mediated alleviation of HS suggesting of its downstream action in NO-mediated heat-tolerance. However, a simultaneous decrease of both (NO and H2S) led to higher Glc-mediated repression of photosynthesis and oxidative stress in terms of increased H2O2 content that was comparable to HS plants. Thus, NO and H2S cooperate to enhance photosynthesis under HS by reducing H2O2-induced oxidative stress and excess Glc-mediated photosynthetic suppression.

Differential Changes in D1 Protein Content and Quantum Yield of Wild and Cultivated Barley Genotypes Caused by Moderate and Severe Drought Stress in Relation to Oxidative Stress

The aim of this study was to investigate the effects of drought stress on oxidative damage and efficiency of PSII photochemistry in barley and compare the varietal response of different genotypes including Yusof (tolerant), Moroc9-75 (sensitive), and wild barley (HS) to drought. Plants were subjected to different levels of soil water availability including control, moderate, and severe drought stress. Exposure to drought stress led to decrease in leaf water potential, biomass production, and stomatal conductance (gs) in all genotypes. Drought induced an increase in H2O2 content followed by increase in malondialdehyde (MDA) as a final result of lipid peroxidation. Drought stress also resulted in reduction of D1 protein content in all genotypes and decreased the maximal quantum yield of PSII photochemistry (FV/FM). These parameters were more affected in Moroc9-75 cultivar by drought stress compare to Yusof and HS genotype. Based on our results, drought-induced reactive oxygen species may decrease PSII photochemistry either through peroxidation of thylakoid membranes or interfering with D1 protein synthesis, necessary for proper function of PSII.

The influence of vitamin E-coated dialysis membrane on oxidative stress during a single session of on-line hemodiafiltration

Background/Aim. Oxidative stress is an important risk factor for the development of cardiovascular atherosclerotic diseases in the population of patients treated with regular hemodialysis. Bioincompatibility of the dialysis membrane and increased concentration of endotoxin in the hemodialysis solution are two main factors that can trigger oxidative stress. This paper was intended to examine the effect of a vitamin E-coated membrane on oxidative stress during a single session of on-line hemodiafiltration. Methods. Twenty-four patients undergoing hemodiafiltration with vitamin E-coated polysulfone dialysis membrane (Leoceed 21H) were examined, followed by a polysulfone dialysis membrane treatment without vitamin E (FX800). The following parameters of oxidative stress were measured: superoxide anion radical (O2-), hydrogen peroxide (H2O2), thiobarbutyric acid reactive substances (TBARS), nitric oxide (NO2-), catalase (CAT), superoxide dizmutase (SOD), and reduced glutathione (GSH) activity. Statistical analysis included the Kolmogorov-Smirnov test, Student-t test and Wilcoxon test. Results. On-line hemodiafiltration using a high-flux polysulfone vitamin E-coated membrane led to significant reduction of TBARS concentration and SOD activity, while the on-line hemodiafiltration session using a high-flux polysulfone membrane that is not vitamin E-coated induced a significant increase in H2O2 concentration in the serum and a decrease in SOD activity. There was no statistical significance among the other parameters of oxidative stress. Conclusion. A single session of on-line hemodiafiltration using a vitamin E-coated polysulfone membrane significantly affects oxidative stress. After a single session of on-line hemodiafiltration using a vitamin E-coated membrane, the concentration of TBARS has significantly decreased. The decreased activity of superoxide dismutase could be a consequence of an increased loss of microelements during an on-line hemodiafiltration session using a high-flux polysulfone membrane. Patient selection, continuous on-line hemodiafiltration using a vitamin E-coated polysulfone membrane over a 3?6 month period and increased antioxidant protection capacity could possibly reduce the risk of cardiovascular morbidity and mortality in patients treated by hemodialysis.

PHOTOLYSIS OF METHYLENE BLUE DYE USING AN ADVANCED OXIDATION PROCESS (ULTRAVIOLET LIGHT AND HYDROGEN PEROXIDE)

Photolysis of methylene blue was studied by using an advanced UV/H2O2 oxidation process. This study investigated different initial dye concentrations (I0, 20, 30 ppm) using different concentrations of H2O2 (10 %, 30%, 50 %) in three additions (5 mL, 10 mL, 15 mL). The results showed that the degradation efficiencies of this dye at different concentrations were as follows: 99.86 % at 10 ppm using 15 mL of 10 % H2O2 after 60 min, 99.22 % at 20 ppm using 15 mL of 30 % H2O2 for 60 min, and 98.90 % at 30ppm using 15 mL of 50 % H2O2 after 90 min. An increase in the optimum concentration of H2O2 was observed with an increase in the initial dye concentration. The de-coloration time also increased with increasing initial dye concentration.

High salt diet contributes to hypertension by weakening the medullary tricarboxylic acid cycle and antioxidant system in Dahl salt-sensitive rats

High salt diet (HSD, 8% NaCl) contributes to salt-sensitive hypertension, this study aimed to determine the effect of HSD on salt-sensitive hypertension by combining proteomic with metabolomics methods. Salt-sensitive rats were fed on HSD and normal salt diet (NSD, 0.4% NaCl) for two weeks before further analysis. Proteomic analysis showed the differential expression proteins (DEPs) were primarily mapped in the tricarboxylic acid (TCA)-cycle, glycolysis/gluconeogenesis, and other pathways associated with multiple amino acids. HSD decreased the medullary activities and protein expression level of two key enzymes of TCA-cycle, MDH and NADP+-IDH. Metabolomics showed three serous TCA-cycle-associated compounds, including decreased malic acid, decreased citric acid, and increased fumaric acid were differentially detected, which resulted in a decrease in NO content and an increase in H2O2 content in serum. The content of GSH, GSH/GSSG ratio, and synthesis substrates of GSH-cysteine and glycine, were significantly decreased by HSD, thus attenuated the antioxidant system in the renal medulla. HSD enhanced the medullary pentose phosphate pathway, which finally increased the concentration of NADPH and NADP+, NADPH/NADP+, and the activity of NADPH oxidase in the renal medulla. Additionally, HSD enhanced the glycolysis pathway in the renal medulla. In summary, HSD significantly weakened the TCA cycle, and attenuated the antioxidant system in the renal medulla, which finally contributed to salt-sensitive hypertension.

Actin filaments mediated root growth inhibition by changing their distribution under UV-B and hydrogen peroxide exposure in Arabidopsis

BackgroundUV-B signaling in plants is mediated by UVR8, which interacts with transcriptional factors to induce root morphogenesis. However, research on the downstream molecules of UVR8 signaling in roots is still scarce. As a wide range of functional cytoskeletons, how actin filaments respond to UV-B-induced root morphogenesis has not been reported. The aim of this study was to investigate the effect of actin filaments on root morphogenesis under UV-B and hydrogen peroxide exposure in Arabidopsis.ResultsA Lifeact-Venus fusion protein was used to stain actin filaments in Arabidopsis. The results showed that UV-B inhibited hypocotyl and root elongation and caused an increase in H2O2 content only in the root but not in the hypocotyl. Additionally, the actin filaments in hypocotyls diffused under UV-B exposure but were gathered in a bundle under the control conditions in either Lifeact-Venus or uvr8 plants. Exogenous H2O2 inhibited root elongation in a dose-dependent manner. The actin filaments changed their distribution from filamentous to punctate in the root tips and mature regions at a lower concentration of H2O2 but aggregated into thick bundles with an abnormal orientation at H2O2 concentrations up to 2 mM. In the root elongation zone, the actin filament arrangement changed from lateral to longitudinal after exposure to H2O2. Actin filaments in the root tip and elongation zone were depolymerized into puncta under UV-B exposure, which showed the same tendency as the low-concentration treatments. The actin filaments were hardly filamentous in the maturation zone. The dynamics of actin filaments in the uvr8 group under UV-B exposure were close to those of the control group.ConclusionsThe results indicate that UV-B inhibited Arabidopsis hypocotyl elongation by reorganizing actin filaments from bundles to a loose arrangement, which was not related to H2O2. UV-B disrupted the dynamics of actin filaments by changing the H2O2 level in Arabidopsis roots. All these results provide an experimental basis for investigating the interaction of UV-B signaling with the cytoskeleton.

The Effects of Silicon and Different Types of Acid Rain on Root Growth and Physiology Activity of Oryza Sativa L. Seedlings.

The effect of silicon (Si) and different types of acid rain (AR) on rice seedling roots was elucidated. The results showed different types of AR had different effects. Nitrate AR at pH 3.0 could promote the growth of rice roots, increased the dry weight, improved root phenotype, boosted H2O2 contents and increased peroxidase, catalase and ascorbate peroxidase activities. Sulfate AR at pH 3.0 could significantly inhibit the growth of rice roots, decreased the dry weight, root phenotype, increased H2O2 content and autioxidant enzyme activities. Sulfate-nitrate AR at pH 3.0 spraying had no significant effect on rice roots. Under different types of AR stress, the addition of exogenous Si could significantly promote the growth of rice seedling roots. This results indicated that the effects of rice root caused by AR might be due to not only the types of AR but also the content of Si in soil.