Accumulation Of Superoxide Radicals Research Articles

24-epibrassinolide enhances drought tolerance in grapevine (Vitis vinifera L.) by regulating carbon and nitrogen metabolism.

Exogenous application of 24-epibrassinolide can alleviate oxidative damage, improve photosynthetic capacity, and regulate carbon and nitrogen assimilation, thus improving the tolerance of grapevine (Vitis vinifera L.) to drought stress. Brassinosteroids (BRs) are a group of plant steroid hormones in plants and are involved in regulating plant tolerance to drought stress. This study aimed to investigate the regulation effects of BRs on the carbon and nitrogen metabolism in grapevine under drought stress. The results indicated that drought stress led to the accumulation of superoxide radicals and hydrogen peroxide and an increase in lipid peroxidation. A reduction in oxidative damage was observed in EBR-pretreated plants, which was probably due to the improved antioxidant concentration. Moreover, exogenous EBR improved the photosynthetic capacity and sucrose phosphate synthase activity, and decreased the sucrose synthase, acid invertase, and neutral invertase, resulting in improved sucrose (190%) and starch (17%) concentrations. Furthermore, EBR pretreatment strengthened nitrate reduction and ammonium assimilation. A 57% increase in nitrate reductase activity and a 13% increase in glutamine synthetase activity were observed in EBR pretreated grapevines. Meanwhile, EBR pretreated plants accumulated a greater amount of proline, which contributed to osmotic adjustment and ROS scavenging. In summary, exogenous EBR enhanced drought tolerance in grapevines by alleviating oxidative damage and regulating carbon and nitrogen metabolism.

Plastid-expressed AdDjSKI enhances photosystem II stability, delays leaf senescence, and increases fruit yield in tomato plants under heat stress.

Heat stress substantially reduces tomato (Solanum lycopersicum) growth and yield globally, thereby jeopardizing food security. DnaJ proteins, constituents of the heat shock protein system, protect cells from diverse environmental stresses as HSP-70 molecular co-chaperones. In this study, we demonstrated that AdDjSKI, a serine-rich DnaJ III protein induced by pathogens, plays an important role in stabilizing photosystem II (PSII) in response to heat stress. Our results revealed that transplastomic tomato plants expressing the AdDjSKI gene exhibited increased levels of total soluble proteins, improved growth and chlorophyll content, reduced malondialdehyde (MDA) accumulation, and diminished PSII photoinhibition under elevated temperatures when compared with wild-type (WT) plants. Intriguingly, these transplastomic plants maintained higher levels of D1 protein under elevated temperatures compared with the WT plants, suggesting that overexpression of AdDjSKI in plastids is crucial for PSII protection, likely due to its chaperone activity. Furthermore, the transplastomic plants displayed lower accumulation of superoxide radical (O2 •─) and H2O2, in comparison with the WT plants, plausibly attributed to higher superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities. This also coincides with an enhanced expression of corresponding genes, including SlCuZnSOD, SlFeSOD, SlAPX2, and SltAPX, under heat stress. Taken together, our findings reveal that chloroplastic expression of AdDjSKI in tomatoes plays a critical role in fruit yield, primarily through a combination of delayed senescence and stabilizing PSII under heat stress.

Redox-active ash gourd extract mitigates salt-stress toxicity through modulation of primary metabolites in rice

Salinity stress is considered as one of the major detrimental stresses for reducing plant growth and crop productivity. Hence, concerted efforts are going on to develop sustainable solutions for reducing salinity-induced negative effects on crop productivity. Given this, the present study evaluated the potential of ash gourd extract (AGE; 0.9 µg/mL) for ameliorating NaCl (100 mM) stress in rice, which is one of the major staple food crops worldwide. The differential phenotyping revealed growth reduction under NaCl treatment, as indicated by 0.27- and 0.36-fold decrease in survival and whole-seedling biomass, respectively, compared with those of control. In contrast, 24 h pre-treatment with AGE before NaCl exposure (AGE24h+NaCl) improved these growth attributes by 1.29- and 1.70-fold, respectively, compared with those of NaCl treatment. The differential phenotype of AGE was associated with its inherent ability to scavenge reactive oxygen species, which was equivalent to 0.08-fold of ascorbic acid. The higher accumulation of superoxide radicals and upregulated expression of stress marker genes including OsTSPO, OsCBS, OsHKT1;5, and OsNHX1 under AGE24h treatment also suggested AGE mediated priming effect. Under AGE24h+NaCl, the expression levels of these stress markers were either maintained or their extent of upregulation was further enhanced. In addition, the coordinated activation of antioxidant machinery and reduced Na-accumulation further supported stress amelioration under AGE24h+NaCl treatment. GC-MS-based metabolomics highlighted fatty acids, malic acid, myo-inositol, allose, trehalose, and L-oxoproline, as key metabolites, associated with AGE-mediated amelioration of NaCl stress. The foliar application of AGE increased seed yield and 1000 seed weight by 1.13- and 1.06-fold, respectively, compared with those of NaCl, validating its agronomic feasibility. Thus, the results highlighted the application of AGE, as a “green” bioregulator for ameliorating NaCl stress conditions in rice.

Overexpression of cat2 restores antioxidant properties and production traits in degenerated strains of Volvariella volvacea

Strain degeneration is an important factor hindering the development of the edible fungus industry. Strain degeneration is associated with the excessive accumulation of reactive oxygen species (ROS) in vivo. Catalase (CAT), an important antioxidant enzyme, can promote the clearance of ROS. In this study, the cat2 gene of Volvariella volvacea was first cloned into an overexpression plasmid via homologous recombination. Finally, through Agrobacterium-mediated transformation, this plasmid was inserted into degenerated strains of V. volvacea T19. The physiological properties, antioxidant properties, ROS content, matrix degradation activity, and cultivation properties of the transformants were tested. The results showed that the cloned cat2 gene was 99.94% similar to the reference sequence. Screening revealed that six positive transformants were successfully obtained. After the overexpression of cat2, the growth rate and biomass of the mycelium increased significantly in the transformant strains (versus the V. volvacea T19 degenerated strains). Moreover, the accumulation of superoxide radical (O2•-) and hydrogen peroxide (H2O2) was significantly reduced, and the activity of the enzymes CAT, superoxide dismutase (SOD), glutathione reductase (GR), and glutathione peroxidase (GPX) was significantly increased. Meanwhile, the expression of cat2, Mnsod1, Mnsod2, gpx, and gr was significantly upregulated, and the activity of eight matrix degradation-related enzymes was increased to varying degrees. More importantly, the overexpression of the cat2 gene promoted the regrowth of fruiting bodies in degenerated strains of V. volvacea T19. This study provides a new biotechnological strategy to control the degeneration of V. volvacea and other edible fungi.

Micro-ridge-furrow soil moisture regulation technology improves seedling quality and yield of winter rapeseed

Rapeseed (Brassica napus L.) is an important oil crop worldwide, and the Yangtze River Basin (YRB) region is one of the most vital rapeseeds producing areas in China. However, the uneven distribution of annual precipitation during the rapeseed seedling stage in this region often leads to droughts and waterlogging, resulting in declined rapeseed seedling quality and yield. Therefore, this study aimed to assess the impact of micro-ridge-furrow planting (MR) and conventional flat cropping planting (FC) under straw returning on rapeseed seedling growth and yield during two growing seasons: wet year (WY) and dry year (DY). In MR planting, rapeseed was sown either on the ridge surface (RS) or in the ridge furrow (RF). We found that MR planting had stronger regulation of soil temperature and humidity compared to FC. The average soil volume water content in RS was 19.2 % lower than FC, while in RF, it was 9.0 % higher than FC. Under MR planting, the daily temperature fluctuations in RF were smaller than in FC, whereas in RS, they were larger than in FC. Through the adjustment of temperature and humidity, MR increased the activities of β-glucosidase (β-Glu) and cellulose disaccharide hydrolase (CBH) in the soil, thereby accelerating rice straw decomposition. Importantly, MR led to improved root growth, seedling quality, precipitation water use efficiency (WUEP), and yield of rapeseed during both the WY and DY seasons. Notably, root morphological traits were significantly altered under straw returning (RT) in MR, particularly with an 11.0 % increase in root surface area, which showed a significant correlation with the indoleacetic acid and jasmonic acid contents in the root system. Furthermore, RT increased antioxidant enzymes activity in rapeseed roots. The H2O2 and ∙OH contents in MR were lower than in FC, indicating that the roots of MR were capable of self-protection and reducing the accumulation of superoxide radicals and peroxides by adapting actively to the soil water environment under straw returning. The yield and WUEP of MR were higher by 11.9 % and 21.0 %, respectively, compared to FC. In conclusion, MR planting has the potential to enhance seedling quality and increase rapeseed yield when combined with rice straw returning. This finding provides technical support for realizing the full and strong seedling establishment and improving the cultivation of direct-seeded rapeseed in the YRB region.

Thymol Induces Cell Death of Fusarium oxysporum f. sp. niveum via Triggering Superoxide Radical Accumulation and Oxidative Injury In Vitro

Fusarium oxysporum f. sp. niveum (FON) causes watermelon wilt that is one of the major disease-causing yield losses of watermelon. Sustainable development of agriculture requires controlling watermelon wilt disease with good environmental performance. One important approach is to identify environmental-friendly compounds with inhibitory activity against FON. Thymol is a plant-derived compound that is safe for ecology. Little is known about the application of thymol in agriculture. In this study, we studied the inhibitory activity of thymol against FON by using morphological, physiological, and histochemical approaches. Thymol significantly inhibited colony diameter of FON in a dose-dependent manner, with EC50 at 21 µg/mL. Thymol at 10, 21, and 35 µg/mL decreased the fresh weight of FON mycelia by 29.0%, 50.6%, and 69.5%, respectively. Microscopic observation revealed irregular damage and loss of shape of mycelia upon thymol exposure. Thymol induced the accumulation of superoxide radical in mycelial cells and accompanied increased activity of antioxidative enzymes (SOD, superoxide dismutase; CAT, catalase). Thymol induced membrane permeability was indicated by lipid peroxidation and electrolyte leakage (increased by 29–58%) in mycelial cells. These results suggested that thymol induced oxidative damage in mycelia, which may be one of the possible reasons for thymol-induced mycelial cell death observed with fluorescent detection. Thymol decreased the production of conidia and inhibited the germination of conidia. Thymol induced superoxide radical accumulation, lipid peroxidation, and cell death in conidia as well. All of these results revealed the inhibitory activity of thymol against FON, which may have resulted from the superoxide radical-induced oxidative injury in both conidia and mycelia of FON.

Key role of reactive oxygen species-scavenging system in nitric oxide and hydrogen sulfide crosstalk-evoked thermotolerance in maize seedlings.

Nitric oxide (NO) and hydrogen sulfide (H2S) are novel signaling molecules, which participate in plant growth, development, and response to stress. In this study root-irrigation with 0.15 mM sodium nitroprusside (SNP, NO donor) up-regulated gene expression of L-CYSTEINE DESULFHYDRASE1 (LCD1), activities of L-cysteine desulfhydrase (LCD) and D-cysteine desulfhydrase (DCD), as well as an endogenous H2S level, compared to control seedlings. The SNP-up-regulated effects were enhanced by 0.5 mM sodium hydrosulfide (NaHS, H2S donor), but weakened by NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) and H2S scavenger hypotaurine (HT) alone. NaHS had no significant effect on gene expression and activity of nitrate reductase (NR, a NO candidate producing enzyme). These data indicate that NO could trigger the LCD/H2S signaling pathway in maize seedlings. To further investigate the effect of NO and H2S crosstalk on thermotolerance in maize seedlings, thermotolerance parameters and reactive oxygen species (ROS)-scavenging system were estimated. The results show that SNP increased survival rate and tissue viability, decreased malondialdehyde (MDA) accumulation, and electrolyte leakage in maize seedlings under heat stress (HS), implying NO could improve thermotolerance in maize seedlings. The NO-improved thermotolerance was impaired by H2S inhibitor DL-propargylglycine (PAG) and scavenger HT alone. Similarly, SNP up-regulated the gene expression of DEHYDROASCORBATE REDUCTASE (DHAR) and GLUTATHIONE REDUCTASE1 (GR1); activities of ascorbate peroxidase, glutathione reductase, and catalase; as well as levels of ascorbic acid, glutathione, flavonoids, carotenoids, and total phenols. SNP also reduced hydrogen peroxide and superoxide radical accumulation in maize seedlings under HS compared to the control. The effects of SNP on ROS and their scavenger system were weakened by PAG and HT alone. These data hint that NO could evoke thermotolerance in maize seedlings by triggering the LCD/H2S signaling pathway, and the ROS-scavenging system played a key role in the NO and H2S crosstalk-evoked thermotolerance.

Anaerobic environment as an efficient approach to improve the photostability of fatty acid photodecarboxylase

Fatty acid photodecarboxylase of Chlorella variabilis NC64A (CvFAP) is a novel photoenzyme with great potential in the treatment of waste lipids and production of sustainable aviation fuel. However, the fragile nature of CvFAP to blue light is an urgent challenge. Herein, we demonstrated anaerobic environment could significantly improve the photostability of CvFAP for the first time. The decarboxylation of palmitic acid by CvFAP for 3 h under anaerobic environment increased pentadecane yield by 44.7% as compared to that under aerobic environment. The residual activity of CvFAP after blue-light preillumination in the absence of palmitic acid for 0.5 h under anaerobic environment was 80.4%, which was 258.7 times higher than that under aerobic environment. Remarkable accumulation of superoxide radical and singlet oxygen in CvFAP under aerobic environment led to the poor photostability of CvFAP. Anaerobic environment helped to mitigate the production of superoxide radical and singlet oxygen in CvFAP, improving the photostability of CvFAP.

The ultra-low O2 environment after anaerobic treatment enhanced the antioxidant properties of Agaricus bisporus mushroom

• Excessive oxidative stress in high O2 environment (19%∼20%)accelerated the quality deterioration of mushrooms. • Ultra-low O2 environment (1%∼2%) improved the antioxidant capacity and reduced oxidative damage. • Ultra-low O2 environment inhibited the browning of mushrooms. • Agaricus bisporus has better anaerobic stress adaptation and hypoxia tolerance. Short-term anaerobic treatment provides significant benefits in maintaining the quality of mushrooms, but this benefit requires re-exposing the mushrooms to a suitable O 2 environment. Hence, this research investigated different re-oxygenation environments after 6 h anaerobic treatment on the antioxidant properties of A. bisporus . Results showed that ultra-low O 2 environment (1%∼2%) reduced the accumulation of superoxide radical (O 2 − ) and hydrogen peroxide (H 2 O 2 ), increased the activity of superoxide dismutase (SOD), catalase (CAT) and aseorbate oxidase (APX) and the content of non-enzymatic antioxidants including flavonoids and ascorbic acid, as well as inhibited browning due to the lowest polyphenol oxidase (PPO) and peroxidase (POD) activities. However, oxidative stress caused by instantaneous high concentration O 2 exposure (19%∼20%) caused severe oxidative damage to tissues and thus showed poor antioxidant properties and color maintenance. In conclusion, the ultra-low O 2 environment after anaerobic treatment can maintain the quality of mushrooms by improving the antioxidant capacity and reducing oxidative damage.

Chitosan and chitosan-derived nanoparticles modulate enhanced immune response in tomato against bacterial wilt disease

The present study evaluated the priming efficacy of chitosan and chitosan-derived nanoparticles (CNPs) against bacterial wilt of tomato. In the current study, seed-treated CNPs plus pathogen-inoculated tomato seedlings recorded significant protection of 62 % against pathogen-induced wilt disease and subsequently better growth. The induced resistance was witnessed by a prominent increase in lignin, callose and H2O2 deposition, followed by superoxide radical accumulation in leaves. Additionally, chitosan and CNPs-treated tomato plants recorded a remarkable increase in the upregulation of phenylalanine ammonia-lyase (PAL), peroxidase (POX), polyphenol oxidase (PPO), catalase (CAT) and β-1, 3 glucanase (GLU) in comparison with untreated plants. The chitosan and CNPs-induced antioxidant enzymes were positively correlated with the stimulation of corresponding gene expression in CNPs treated plants related to pathogen-inoculated ones. The results of this study describe that how the application of chitosan and CNPs elicit defense responses at the cellular, biochemical and gene expression in tomato plants against bacterial wilt disease, thereby improve growth and yield.

Role of Superoxide Dismutase in Amyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis (ALS), or Lou Gehrig's disease, is an adult‐onset neurodegenerative disorder that has been linked to over 200 mutations from the SOD1 gene. The protein created from this gene is superoxide dismutase (SOD1), an enzyme responsible for breaking down toxic superoxide radicals by facilitating the binding to zinc and copper. Superoxide dismutase is a homodimer, composed of two identical subunits, and is located in the cytoplasm of the cell, Each subunit has 154 amino acid residues with a β‐barrel core, formed by 8 beta‐sheets, and three outer loops which are linked together by a disulfide bond, a hydrogen bond network, and a metal‐binding site for both zinc and copper. This metal‐binding site is responsible for the catalyzation of superoxide radicals to hydrogen peroxide and dioxygen. The redox reactions that SOD1 allows to occur are the oxidation of superoxide to dioxygen and the reduction of superoxide to hydrogen peroxide while alternating the oxidation states of Copper. The zinc molecule acts as a structural element for the reaction. The catalyzation of superoxide radicals to safer components occurs because the accumulation of superoxide radicals is toxic to the cell, and can lead to cell death. Another role of SOD1 is its responsibility in preventing oxidative stress. Oxidative stress is the result of the imbalance between reactive oxygen species such as superoxide, and the activity of superoxide dismutase to detoxify the affected areas. In cases of ALS, mutations cause this accumulation, which leads to motor neuron death. The most common mutation of SOD1 in the United States, as well as the one that causes the fastest onset for ALS to occur, is A5V, which is the replacement of the alanine residue with valine at position 5. This mutation can result in not only the accumulation of superoxide radicals but also the production of more neurotoxic radicals and fibrillar aggregates of misfolded SOD1, which can occur due to the absence of the disulfide bond or bound zinc ions. These effects lead to motor neuron death, which manifests as the symptoms of ALS. The symptoms of ALS are progressive muscle weakness, loss of voluntary muscle control, the decline of the ability to initiate movement, and paralysis. ALS, especially as a result of the A5V mutation, often leads to a shorter life expectancy. Amyotrophic Lateral Sclerosis currently has no cure, but there are many evolving therapies for the disease. Patients with ALS are encouraged to participate in gentle, low‐impact physical therapies and use special equipment to support communication, nutrition, and breathing. The drugs approved by the FDA to help treat ALS include Riluzole (Rilutek), which reduces damage to cells by blocking the release of glutamate, and Edaravone (Radicava) which removes free radicals. In addition, small‐molecule therapies are being developed to stabilize the native form of SOD1 in the absence of zinc or in the presence of protein mutations, which may reduce the effects of the manifestation of the disease. Further research is needed to determine specifically how mutations of SOD1 lead to motor neuron death, and the resulting symptoms of Amyotrophic Lateral Sclerosis.

Differential Metabolomic Responses of Kentucky Bluegrass Cultivars to Low Nitrogen Stress.

Kentucky bluegrass (Poa pratensis L.) is a cool-season turfgrass species that responds strongly to nitrogen (N), but the metabolomic responses of this grass species to N supply is unknown. The N-tolerant cultivar Bluemoon and N-sensitive cultivar Balin were exposed to normal N (15 mM) and low N (0.5 mM) for 21 days for identification of differentially expressed metabolites (DEMs) between normal N and low N treatments. Balin had more reductions of chlorophyll and total soluble protein concentrations and a higher accumulation of superoxide radicals under low N stress. A total of 99 known DEMs were identified in either cultivar or both including 22 amino acids and derivatives, 16 carbohydrates, 29 organic acids, and 32 other metabolites. In Bluemoon, β-alanine metabolism was most enriched, followed by alanine, aspartate, and glutamate metabolism, biosynthesis of valine, leucine, and isoleucine biosynthesis, and glycine, serine, and threonine metabolism. In Balin, alanine, aspartate, and glutamate metabolism were most enriched, followed by the tricarboxylic acid (TCA), glyoxylate and decarbohydrate metabolism, and carbon fixation. Bluemoon generally maintained higher TCA cycle capacity and had more downregulated amino acids, while changes in more organic acids occurred in Balin under low N stress. Some metabolite changes by low-N stress were cultivar-specific. The results suggested that regulation of metabolites related to energy production or energy saving could contribute to low N tolerance in Kentucky bluegrass.

Влияние окислительного стресса на антиоксидантную защиту растений

The effect of long-term combined exposure to temperature stress and viral infection on the antioxidant defense system of Nicotiana benthamiana plants was studied in this work. It was shown that oxidative stress caused by the combined action of biotic and abiotic factors has an ambiguous effect on the development of the pathogen in the leaves of Nicotiana benthamiana plants. The article shows the heterogeneity of the impact of heat and cold stress and viral infection on the content of reactive oxygen species in the leaves of Nicotiana benthamiana plants. Thus, it was shown that low-temperature stress led to an increase in the level of accumulation of superoxide radical in plant leaves, while the effect of combined stress did not lead to a greater increase in the accumulation of superoxide radical. The combined effect of cold stress and viral infection led to an increase in the content of hydrogen peroxide, while there was reduced catalase activity. At the same time, a sharp increase in aldehyde oxidase activity was observed under temperature stress. The highest activity of the enzyme was observed under the combined effect of low temperature and viral infection. Thus, it can be assumed that oxidative stress in plant tissues leads to an increase in the level of accumulation of reactive oxygen species while affecting the enzymes responsible for the balance of accumulation of reactive oxygen species in plant tissue in response to a pathogen attack.

Characterization of the voltage-dependent anion channel (VDAC) gene family in wheat (Triticum aestivum L.) and its potential mechanism in response to drought and salinity stresses.

Voltage-dependent anion channels (VDACs) are major transport proteins localized in the outer membrane of mitochondria and play critical roles in regulating plant growth and responding to stress. In this study, a total of 26 VDAC genes in common wheat (Triticum aestivum L.) were identified. TaVDACs that contained β-barrel structures were classified into three groups with phylogenetic and sequence alignment. Additionally, the gene structure and protein conserved motif composition varied among diverse subfamilies but were relatively conserved within the same subfamily. The basic elements that were stress- and hormone-related, including TATA-box, CAAT-box, MBS, LTR, TC-rich repeats, ABRE, P-box and TATC-box, were predicted within the promoter region of TaVDAC genes. TaVDAC expression patterns differed among tissues, organs and abiotic stress conditions. Overexpression (OE) of TaVDAC1-B conferred high tolerance to salinity and less resistance to drought stress in Arabidopsis thaliana. TaVDAC1-B interacted with Nucleoredoxin-D1 (TaNRX-D1) protein. Furthermore, compared with WT lines, salinity stress further upregulated the level of AtNRX1 (homologous gene of TaNRX-D1 in Arabidopsis) expression and the activity of superoxide dismutase in TaVDAC1-B OE lines, which led to a decrease in superoxide radical accumulation; drought stress further downregulated AtNRX1 expression and superoxide dismutase activity in TaVDAC1-B OE lines, resulting in the accumulation of superoxide radicals. Our study not only presents comprehensive information for understanding the VDAC gene family in wheat but also proposes a potential mechanism in response to drought and salinity stress.

Interaction of elevated CO2 and form of nitrogen nutrition alters leaf abaxial and adaxial epidermal and stomatal anatomy of wheat seedlings.

Plant's stomatal physiology and anatomical features are highly plastic and are influenced by diverse environmental signals including the concentration of atmospheric CO2 and nutrient availability. Recent reports suggest that the form of nitrogen (N) is a determinant of plant growth and nutrient nitrogen use efficiency (NUE) under elevated CO2 (EC). Previously, we found that high nitrate availability resulted in early senescence, enhanced reactive oxygen species (ROS), and reactive nitrogen species (RNS) production and also that mixed nutrition of nitrate and ammonium ions were beneficial than sole nitrate nutrition in wheat. In this study, the interactive effects of different N forms (nitrate, ammonium, mixed nutrition of nitrate, and ammonium) and EC on epidermal and stomatal morphology were analyzed. Wheat seedlings were grown at two different CO2 levels and supplied with media devoid of N (N0) or with nitrate-N (NN), mixed nutrition of ammonium and nitrate (MN), or only ammonium-N (AN). The stoma length increased significantly in nitrate nutrition with a consistent reduction in stoma width. Guard cell length was higher in EC treatment as compared to AC. The guard cell width was maximum in AN-grown plants at EC. Epidermal cell density and stomatal density were lower at EC. Nitrate nutrition increased the stomatal area at EC while the reverse was true for MN and AN. Wheat plants fertilized with AN showed a higher accumulation of superoxide radical (SOR) at EC, while in NN treatment, the accumulation of hydrogen peroxide (H2O2) was higher at EC. Reactive oxygen species, particularly H2O2, can trigger mitogen-activated protein kinase (MAPK) mediated signaling and its crosstalk with abscisic acid (ABA) signaling to regulate stomatal anatomy in nitrate-fed plants. The SOR accumulation in ammonium- and ammonium nitrate-fed plants and H2O2 in NN-fed plants might finely regulate the sensitivity of stomata to alter water/nutrient use efficiency and productivity under EC. The data reveals that the variation in anatomical attributes viz. cell length, number of cells, etc. affected the leaf growth responses to EC and forms of N nutrition. These attributes are fine targets for effective manipulation of growth responses to EC.

Survival from paraquat induced renal impairment in a 17 years old male

N, N’-dimethyl-4, 4’-bipyridinium dichloride (paraquat) is a herbicide commonly used in India that leads to fatal outcome on ingestion. Paraquat interferes in the intracellular electron transfer systems inhibiting the reduction of NADP to NADPH resulting in accumulation of superoxide radical causing lipid cell membranes destruction leading to various organ damage. Life threatening effects such as acute kidney injury as paraquat elimination is mainly by kidney, acute respiratory distress syndrome and multi-organ failure are the causes of mortality in paraquat poisoning. There is no specific antidotes for paraquat poisoning so prevention and aggressive decontamination remains the mainstay of management in case of exposure or ingestion. Paraquat poisoning presentation may vary in cases depending on the amount of paraquat consumed and thus the outcome. Here we report a case of a 17 years old male who presented with acute kidney injury following ingestion of paraquat in a suicidal attempt. In our case, induced vomiting of the stomach content readily after ingestion of the poison, early haemodialysis, use of immunosuppression such as methylprednisolone, cyclophosphamide and antioxidants such as acetylcysteine, Vitamin C and Vitamin E as free radical scavenging agent , supportive measures such as adequate hydration and antibiotics might have helped in the patient’s survival. The case fatality remains very high in paraquat poisoning till date owing to lack of effective treatment options.

Cathepsin A contributes to left ventricular remodeling by degrading extracellular superoxide dismutase in mice

In the heart, the serine carboxypeptidase cathepsin A (CatA) is distributed between lysosomes and the extracellular matrix (ECM). CatA-mediated degradation of extracellular peptides may contribute to ECM remodeling and left ventricular (LV) dysfunction. Here, we aimed to evaluate the effects of CatA overexpression on LV remodeling. A proteomic analysis of the secretome of adult mouse cardiac fibroblasts upon digestion by CatA identified the extracellular antioxidant enzyme superoxide dismutase (EC-SOD) as a novel substrate of CatA, which decreased EC-SOD abundance 5-fold. In vitro, both cardiomyocytes and cardiac fibroblasts expressed and secreted CatA protein, and only cardiac fibroblasts expressed and secreted EC-SOD protein. Cardiomyocyte-specific CatA overexpression and increased CatA activity in the LV of transgenic mice (CatA-TG) reduced EC-SOD protein levels by 43%. Loss of EC-SOD-mediated antioxidative activity resulted in significant accumulation of superoxide radicals (WT, 4.54 μmol/mg tissue/min; CatA-TG, 8.62 μmol/mg tissue/min), increased inflammation, myocyte hypertrophy (WT, 19.8 μm; CatA-TG, 21.9 μm), cellular apoptosis, and elevated mRNA expression of hypertrophy-related and profibrotic marker genes, without affecting intracellular detoxifying proteins. In CatA-TG mice, LV interstitial fibrosis formation was enhanced by 19%, and the type I/type III collagen ratio was shifted toward higher abundance of collagen I fibers. Cardiac remodeling in CatA-TG was accompanied by an increased LV weight/body weight ratio and LV end diastolic volume (WT, 50.8 μl; CatA-TG, 61.9 μl). In conclusion, CatA-mediated EC-SOD reduction in the heart contributes to increased oxidative stress, myocyte hypertrophy, ECM remodeling, and inflammation, implicating CatA as a potential therapeutic target to prevent ventricular remodeling.

Silicon-Mediated Physiological and Agronomic Responses of Maize to Drought Stress Imposed at the Vegetative and Reproductive Stages

Silicon (Si) enhances maize resistance to drought. While previous studies have mainly focused on the seedling stage, the mediation of drought stress by Si imposed at the vegetative and reproductive stages has been rarely investigated. A soil-column experiment was thus conducted under a rainproof shelter to quantify the effect s of Si application on the physiological and agronomic responses of maize to drought stress imposed at the 6-leaf (D-V6), 12-leaf (D-V12), and blister (D-R2) stages. The observed parameters included plant growth, photosynthesis, osmolytes, antioxidant activity, and grain yield. The results showed that drought stress strongly decreased the leaf area, leaf water content, photosynthetic rate, chlorophyll content, and antioxidant activity (superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)) and markedly increased lipid peroxidation. D-V6, D-V12, and D-R2 decreased grain yields by 12.9%, 28.9%, and 44.8%, respectively, compared to the well-watered treatment (CK). However, Si application markedly increased leaf area, chlorophyll content, photosynthetic rate, osmolyte content, and enzymatic antioxidant activities (SOD, POD, and CAT), and decreased malondialdehyde (MDA) and superoxide radical accumulation, ultimately improving maize yields by 12.4%, 69.8%, and 80.8%, respectively, compared to the non-Si treated plants under drought stress at the V6, V12, and R2 stages. Furthermore, maize yields had a significant positive correlation with chlorophyll content and SOD and POD activity during the three stages. Our findings suggest that Si-induced changes in chlorophyll content and antioxidant activity might constitute important mechanisms for mitigating drought stress. In conclusion, this study provides physico-biochemical evidence for the beneficial role of Si in alleviating drought-induced yield reduction in maize, particularly during the late vegetative or early reproductive stages. Thus, Si application constitutes an effective approach for improving maize yield in rain-fed agricultural systems.

P0914NEUTROPHIL EXTRACELLULAR TRAPS FORMATION IN HEMODIALYSIS PATIENTS

Abstract Background and Aims Hemodialysis (HD) patients suffer from devastatingly high rates of morbidity and mortality due to infections. Neutrophils isolated from HD patients were shown in the past to exhibit impaired phagocytosis in a mechanism yet to be completely elucidated. In 2004, Brinkmann et al. were the first to describe a new form of cell death which they termed Neutrophil Extracellular Trap Formation, or NETosis, in which neutrophils expulse batches of DNA and proteins in response to bacterial or chemical stimuli in order to trap and remove the stimulus. NETosis is further divided into two pathways, NADPH oxidase (NOX)-dependent and NOX-independent, induced in vitro by phorbol 12-myristate 13-acetate (PMA) and Calcium Ionophore (CI), respectively. In this research, we aim to assess the capacities of HD neutrophils to engage in NETosis, hypothesizing they might be diminished similarly to their phagocytic capacities, and to elucidate the underlying mechanism behind this impairment. Method Neutrophils were isolated from whole venous blood of normal controls and from the arterial line of HD patients before the onset of a dialysis session using EasySepTM direct human neutrophils isolation kit. Then, NETosis was induced with either PMA, Calcium Ionophore A23187 or Phosphate-buffered saline (PBS) as negative control. cfDNA released from the cells was quantified by measuring SYTOXTM-green nucleic acid stain fluorescence levels in the supernatant after stimulation using Elisa plate reader and morphological analysis was done under fluorescence microscope. Reactive oxygen species levels were quantified using flow cytometry and superoxide dismutase (SOD) activity was measured using the SOD Assay Kit (Sigma-Aldrich). Protein arginine deiminase 4 (PAD4) expression was assessed by western blotting. Hydrogen peroxide (H2O2) was added exogenously in order to restore NETosis. Results HD isolated neutrophils exhibit decreased NETosis compared with normal controls in response to both PMA in the NOX-dependent pathway and CI in the NOX-independent pathway, as measured by immunofluorescence and cfDNA quantification. In the NOX-dependent pathway SOD activity was found to be 14% decreased in HD patients, resulting in the accumulation of superoxide radicals and decreased production of H2O2. In the NOX-independent pathway, PAD4 expression was found to be significantly decreased as well. NET formation was restored in vitro in HD neutrophils by the addition of exogenous H2O2. Conclusion To date, impaired NETosis was described only in congenital conditions such as chronic granulomatous disease and myeloperoxidase deficiency. To our knowledge, our research is the first to describe an acquired defect in NETosis in end stage renal disease patients undergoing chronic hemodialysis. An intervention aimed to improve neutrophil function in these patients may reduce the morbidity and mortality due to infection-related disease.

DFIQ, a Novel Quinoline Derivative, Shows Anticancer Potential by Inducing Apoptosis and Autophagy in NSCLC Cell and In Vivo Zebrafish Xenograft Models.

Lung cancer is one of the deadliest cancers worldwide due to chemoresistance in patients with late-stage disease. Quinoline derivatives show biological activity against HIV, malaria, bacteriuria, and cancer. DFIQ is a novel synthetic quinoline derivative that induces cell death in both in vitro and in vivo zebrafish xenograft models. DFIQ induced cell death, including apoptosis, and the IC50 values were 4.16 and 2.31 μM at 24 and 48 h, respectively. DFIQ was also found to induce apoptotic protein cleavage and DNA damage, reduce cell cycle-associated protein expression, and disrupt reactive oxygen species (ROS) reduction, thus resulting in the accumulation of superoxide radicals. Autophagy is also a necessary process associated with chemotherapy-induced cell death. Lysosome accumulation and lysosome-associated membrane protein-2 (LAMP2) depletion were observed after DFIQ treatment, and cell death induction was restored upon treatment with the autophagy inhibitor 3-methyladenine (3-MA). Nevertheless, ROS production was found to be involved in DFIQ-induced autophagy activation and LAMP2 depletion. Our data provide the first evidence for developing DFIQ for clinical usage and show the regulatory mechanism by which DFIQ affects ROS, autophagy, and apoptosis.