H2O2 Scavenging Capacity Research Articles

The zinc finger protein DHHC09 S-acylates the kinase STRK1 to regulate H2O2 homeostasis and promote salt tolerance in rice.

Soil salinity results in oxidative stress and heavy losses to crop production. The S-acylated protein SALT TOLERANCE RECEPTOR-LIKE CYTOPLASMIC KINASE 1 (STRK1) phosphorylates and activates CATALASE C (CatC) to improve rice (Oryza sativa L.) salt tolerance, but the molecular mechanism underlying its S-acylation involved in salt signal transduction awaits elucidation. Here, we show that the DHHC-type zinc finger protein DHHC09 S-acylates STRK1 at Cys5, Cys10, and Cys14 and promotes salt and oxidative stress tolerance by enhancing rice H2O2-scavenging capacity. This modification determines STRK1 targeting to the plasma membrane or lipid nanodomains and is required for its function. DHHC09 promotes salt signaling from STRK1 to CatC via transphosphorylation, and its deficiency impairs salt signal transduction. Our findings demonstrate that DHHC09 S-acylates and anchors STRK1 to the plasma membrane to promote salt signaling from STRK1 to CatC, thereby regulating H2O2 homeostasis and improving salt stress tolerance in rice. Moreover, overexpression of DHHC09 in rice mitigates grain yield loss under salt stress. Together, these results shed light on the mechanism underlying the role of S-acylation in RLK/RLCK-mediated salt signal transduction and provide a strategy for breeding highly salt-tolerant rice.

Tatlı Patates ve Gölevezin Bazı Biyoaktif Bileşenleri: Bitki Organlarına Dayalı Karşılaştırmalı Bir Çalışma

This study was carried out to evaluate the variability and distribution of bioactive components of different organs of sweet potato and taro plants grown locally in Turkey. Samples extracted from different organs of these two species (tubers and leaves of sweet potato; leaves, petioles, main tubers, and lateral tubers of taro) were evaluated. Total water-soluble protein, total flavonoids, total phenolics, H2O2 scavenging capacity, carotenoids, FRAP antioxidant capacity, CUPRAC antioxidant capacity, and total dry matter parameters of two different species and their organs were measured. The difference between the organ averages for all parameters examined was statistically significant. In general, leaves of both species had the highest content for all parameters except total dry matter and CUPRAC antioxidant capacity. The effectiveness of the parameters in explaining variation in the gene pool was also examined using principal component analysis. All parameters contributed highly to the variation except H2O2 capacity, total dry matter content, and CUPRAC antioxidant capacity. According to the findings, there is a high variation between each species and between the organs. These results will guide future studies on these two species.

The protein phosphatase PC1 dephosphorylates and deactivates CatC to negatively regulate H2O2 homeostasis and salt tolerance in rice.

Catalase (CAT) is often phosphorylated and activated by protein kinases to maintain hydrogen peroxide (H2O2) homeostasis and protect cells against stresses, but whether and how CAT is switched off by protein phosphatases remains inconclusive. Here, we identified a manganese (Mn2+)-dependent protein phosphatase, which we named PHOSPHATASE OF CATALASE 1 (PC1), from rice (Oryza sativa L.) that negatively regulates salt and oxidative stress tolerance. PC1 specifically dephosphorylates CatC at Ser-9 to inhibit its tetramerization and thus activity in the peroxisome. PC1 overexpressing lines exhibited hypersensitivity to salt and oxidative stresses with a lower phospho-serine level of CATs. Phosphatase activity and seminal root growth assays indicated that PC1 promotes growth and plays a vital role during the transition from salt stress to normal growth conditions. Our findings demonstrate that PC1 acts as a molecular switch to dephosphorylate and deactivate CatC and negatively regulate H2O2 homeostasis and salt tolerance in rice. Moreover, knockout of PC1 not only improved H2O2-scavenging capacity and salt tolerance but also limited rice grain yield loss under salt stress conditions. Together, these results shed light on the mechanisms that switch off CAT and provide a strategy for breeding highly salt-tolerant rice.

Trx CDSP32-overexpressing tobacco plants improves cadmium tolerance by modulating antioxidant mechanism

The effects of overexpression of the thioredoxin-like protein CDSP32 (Trx CDSP32) on reactive oxygen species (ROS) metabolism in tobacco leaves exposed to cadmium (Cd) were studied by combining physiological measures and proteomics technology. Thus, the number of differentially expressed proteins (DEPs) in plants overexpressing the Trx CDSP32 gene in tobacco (OE) was observed to be evidently lower than that in wild-type (WT) tobacco under Cd exposure, especially the number of down-regulated DEPs. Cd exposure induced disordered ROS metabolism in tobacco leaves. Although Cd exposure inhibited the activities of superoxide dismutase (SOD), catalase (CAT), and l-ascorbate peroxidase (APX) and the expression of proteins related to the thioredoxin-peroxiredoxin (Trx-Prx) pathway, the increase in the activities of peroxidase (POD), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR), glutathione peroxidase (GPX), and glutathione S-transferase (GST) and their protein expression levels played an important role in the physiological response to Cd exposure. Notably, Trx CDSP32 was observed to alleviate the decrease in the expression and activities of SOD and CAT caused by Cd exposure and enhance the function of POD. Trx CDSP32 was observed to increase the H2O2 scavenging capacity of the ascorbic acid-glutathione (AsA-GSH) cycle and Trx-Prx pathway under Cd exposure, and it can especially regulate 2-Cys peroxiredoxin (2-Cys Prx) protein expression and thioredoxin peroxidase (TPX) activity. Thus, overexpression of the Trx CDSP32 gene can alleviate the oxidative damage that occurs in tobacco leaves under Cd exposure by modulating antioxidant defense systems.

TGF-β1 Disrupts redox balance in PCCL3 thyroid cell and is sexually dimorphic expressed in rat thyroid gland

Thyroid diseases are more prevalent in women, and this difference seems to be associated with the oxidative stress found in the thyroid of females. Thyroid NADPH Oxidase 4 (NOX4) was shown to respond to estrogen, which can also modulate TGF-β1, a potent stimulator of NOX4. This study aimed to investigate the effects of TGF-β1 on redox homeostasis parameters in the rat thyroid cell PCCL3 and the interrelationship between estrogen and TGF-β1. TGF-β1 treatment increased both intra- and extracellular ROS generation along with NOX4 expression and reduced GPX and catalase activities, extracellular H2O2 scavenging capacity, and reduced thiol content. TGF-β1 mRNA and protein expression are higher in female thyroid glands of rats in comparison to males. Moreover, 17β-estradiol treatment enhanced TGF-β1 mRNA in PCCL3 cells, decreased extracellular bioavailability but did not activate Smad pathway. Our data suggest that higher levels of TGF-β1 in females are potentially related to higher ROS availability which may be associated with the sex disparity in thyroid disorders.

Anthelminthic, Anti-Inflammatory, Antioxidant, and Antimicrobial Activities and FTIR Analyses of Vernonia camporum Stem-Bark

Vernonia camporum is used ethnomedicinally to treat diseases such as malaria, fever, hypertension, mouth sores, pains, inflammation, and skin rashes in Africa. This study aims at investigating the biological activities (anthelminthic, anti-inflammatory, antioxidant, and antimicrobial) and separating some of the biologically active components in the methanol crude extract of the stem-bark of Vernonia camporum. Phytochemical screening, anthelminthic (Lumbricus terrestris (earthworm)), anti-inflammatory (egg albumin denaturation), antioxidant (DPPH and H2O2 scavenging and total antioxidant capacity (TAC)), and antimicrobial (agar and broth dilution method) assays were performed on the extracts. Column chromatography and FTIR spectroscopic analysis were employed to separate and analyze the least polar constituents of the methanol extract. The preliminary phytochemical analyses revealed the presence of secondary metabolites such as alkaloids, phenols, tannins, saponins, terpenoids, flavonoids, steroids, phytosterols, proteins and amino acids, phlobatannins, glycosides, cardiac glycosides, coumarins, and anthocyanins. The extracts (methanol and hexane) showed a higher concentration-dependent anthelminthic activity. The extracts exhibited high concentration-dependent anti-inflammatory activities with IC50 values of 35.83 ± 3.984 and 53.91 ± 5.8413 µg/mL, respectively. The IC50 values for methanol and hexane extracts in the DPPH assay were 17.70 ± 3.430 and 29.54 ± 1.5437 µg/mL, and those of the H2O2 assay were 243.20 ± 0.1528 and 352.20 ± 12.64 µg/mL, respectively. TAC results for methanol and hexane extracts were recorded as 31.592 ± 1.682 and 30.232 ± 0.445 gAAE/100 g, respectively. The extracts were observed to exhibit antimicrobial activity against test organisms with MICs ranging from 0.1953 to 25.00 mg/mL. Chromatographic separations gave four fractions. FTIR analysis indicated the presence of various functional groups in purified fractions of the methanol extract that confirms the presence of the phytochemicals identified in the screening test. The results indicate that both extracts of V. camporum possess anthelminthic, anti-inflammatory, antioxidant, and antimicrobial activities supporting the traditional usage of this plant.

Chemical Genetics Approach Identifies Abnormal Inflorescence Meristem 1 as a Putative Target of a Novel Sulfonamide That Protects Catalase2-Deficient Arabidopsis against Photorespiratory Stress.

Alterations of hydrogen peroxide (H2O2) levels have a profound impact on numerous signaling cascades orchestrating plant growth, development, and stress signaling, including programmed cell death. To expand the repertoire of known molecular mechanisms implicated in H2O2 signaling, we performed a forward chemical screen to identify small molecules that could alleviate the photorespiratory-induced cell death phenotype of Arabidopsis thaliana mutants lacking H2O2-scavenging capacity by peroxisomal catalase2. Here, we report the characterization of pakerine, an m-sulfamoyl benzamide from the sulfonamide family. Pakerine alleviates the cell death phenotype of cat2 mutants exposed to photorespiration-promoting conditions and delays dark-induced senescence in wild-type Arabidopsis leaves. By using a combination of transcriptomics, metabolomics, and affinity purification, we identified abnormal inflorescence meristem 1 (AIM1) as a putative protein target of pakerine. AIM1 is a 3-hydroxyacyl-CoA dehydrogenase involved in fatty acid β-oxidation that contributes to jasmonic acid (JA) and salicylic acid (SA) biosynthesis. Whereas intact JA biosynthesis was not required for pakerine bioactivity, our results point toward a role for β-oxidation-dependent SA production in the execution of H2O2-mediated cell death.

Y2SK2- and SK3-type dehydrins from Agapanthus praecox act as protectants to improve plant cell viability during cryopreservation

The cryopreservation of plants through vitrification prevents ice damage by bringing the plants to a glassy state for cryogenic storage. Most angiosperm seeds are dehydrated to extremely low levels of their original water content, accumulate late embryogenesis abundant (LEA) proteins, and greatly increase their cytoplasmic viscosity, thereby reaching a glassy state during maturation. In this study, two LEA family recombinant dehydrin (DHN) proteins (Y2SK2 and SK3) from Agapanthus praecox, when added to the plant vitrification solution, were found to double the survival rate of Arabidopsis thaliana seedlings after cryopreservation. Evans blue staining revealed that the Y2SK2 and SK3 proteins decreased the damage to the plasma membranes of plant cells during cryopreservation. Furthermore, the Y2SK2 and SK3 proteins significantly decreased the malondialdehyde and H2O2 contents, increased the glutathione (GSH) content, and downregulated NADPH oxidase (RbohA) in A. thaliana seedlings. Thus, these DHNs may reduce excessive reactive oxygen species production and membrane lipid peroxidation damage under the complex stresses of cryopreservation. Additionally, Y2SK2 can effectively enhance peroxidase activity and catalase2 (CAT2) expression levels; SK3 obviously improved ascorbic acid (AsA) content, as well as Cu/Zn superoxide dismutase (Cu/Zn-SOD) and ascorbate peroxidase 5 (APX5) expression in plant cells and enhanced H2O2 scavenging capacity by promoting the activity of the AsA-GSH cycle. These findings suggested that Y2SK2 and SK3, the DHNs added at the dehydration step, can relieve cell cryoinjury by inducing high antioxidant levels and positive oxidative stress responses and act as protectants, improving plant cell viability after cryopreservation. Application of dehydrins optimization plant cryopreservation protocol, dehydrins can significantly improve complex stress damage and enhance the cell viability from cryopreservation.

Arabidopsis thaliana WRKY25 Transcription Factor Mediates Oxidative Stress Tolerance and Regulates Senescence in a Redox-Dependent Manner.

Senescence is the last developmental step in plant life and is accompanied by a massive change in gene expression implying a strong participation of transcriptional regulators. In the past decade, the WRKY53 transcription factor was disclosed to be a central node of a complex regulatory network of leaf senescence and to underlie a tight multi-layer control of expression, activity and protein stability. Here, we identify WRKY25 as a redox-sensitive up-stream regulatory factor of WRKY53 expression. Under non-oxidizing conditions, WRKY25 binds to a specific W-box in the WRKY53 promoter and acts as a positive regulator of WRKY53 expression in a transient expression system using Arabidopsis protoplasts, whereas oxidizing conditions dampened the action of WRKY25. However, overexpression of WRKY25 did not accelerate senescence but increased lifespan of Arabidopsis plants, whereas the knock-out of the gene resulted in the opposite phenotype, indicating a more complex regulatory function of WRKY25 within the WRKY subnetwork of senescence regulation. In addition, overexpression of WRKY25 mediated higher tolerance to oxidative stress and the intracellular H2O2 level is lower in WRKY25 overexpressing plants and higher in wrky25 mutants compared to wildtype plants suggesting that WRKY25 is also involved in controlling intracellular redox conditions. Consistently, WRKY25 overexpressers had higher and wrky mutants lower H2O2 scavenging capacity. Like already shown for WRKY53, MEKK1 positively influenced the activation potential of WRKY25 on the WRKY53 promoter. Taken together, WRKY53, WRKY25, MEKK1 and H2O2 interplay with each other in a complex network. As H2O2 signaling molecule participates in many stress responses, WRKK25 acts most likely as integrators of environmental signals into senescence regulation.

Effects of ripening stage on the content and antioxidant capacities of phenolic compounds of arils, seeds and husks of ackee fruit Blighia sapida Köenig

The aim of this study were to reveal the profile and the antioxidant capacities of total phenolic compounds (TPC) of arils, seeds and husks of ackee fruit of different ripening stages. Fruits were harvest at not open, mid open and fully open pods stages. Phenolic compounds profiled using UHPLC-MS/MS revealed a total of seventeen different phenolics. The highest level (15 mg/g DW) noted was vanillic acid in the seeds of not open pods, while the lowest level (0.1 mg/g DW) noted were gallic acid and ferulic acid in the arils and the husks of not open pods. During ripening, TPC decreased in the arils, but increased in the seeds and husk. TPC ranged from lowest value of 244.29 μg/g DW in the arils of fully open pods to the highest value of 652.72 μg/g DW in the husks of fully open pods. The husks of fully open pods exhibited the highest DPPH-radical scavenging capacity, H2O2 scavenging capacity and the reducing power capacity, while the seeds exhibited the lowest values. On the other hand, high correlation was found between TPC and antioxidant capacities. Conclusively, the results of this study provide important information on the phenolic compounds profile and their antioxidant properties of different of ackee fruit harvested at different ripening stages, and this information is very useful for determining the nutritional quality of this fruit for better use either in human, animal or industry.

Anthocyanins, non-anthocyanin phenolics, tocopherols and antioxidant capacity of açaí juice (Euterpe oleracea) as affected by high pressure processing and thermal pasteurization

Abstract We studied the effect of high pressure processing (HPP) (400, 450, 500, and 600 MPa/5 min/20 °C) and thermal pasteurization (85 °C/1 min) on anthocyanins, non-anthocyanin phenolic compounds, tocopherols and antioxidant capacity toward oxygen and nitrogen reactive species of acai juice. HPP was more effective for the preservation of anthocyanins than thermal pasteurization (up to 40%), probably due to its thermal-sensitivity. A significant increase was observed for the non-anthocyanin compounds' content at 500 MPa, possibly related to cell wall rupture due to the applied pressure. As a result, this sample showed greater antioxidant capacity (ORAC and total phenolic compounds). On the other hand, H2O2 scavenging capacity, tocopherols and vitamin E activity were not affected, whereas scavenging capacity against HOCl and NOC formation was not well correlated with bioactive compounds concentration. Nevertheless, these properties were effectively preserved in HPP treatments. These results indicate that HPP may provide acai juice with high functional quality. Industrial relevance Acai juice (AJ) has been increasingly valued worldwide due to its bioactive compounds and health-promoting effects, however, thermal pasteurization (TP), usually applied to AJ preservation, may cause degradation of these compounds and damage AJ bioactivities. Our results contribute to understanding how the main bioactive compounds and functional properties of AJ are affected by high pressure processing (HPP) and TP. In addition, they represent an important advance in the field of emerging preservation technologies as it indicates optimal high pressure conditions for AJ processing. Ultimately, given that HPP adds values to food products, our results may be used by the food industry to produce new acai-based formulations with high market value.

In vivo immunomodulatory and antioxidant properties of nanoceria (nCeO2) in the marine mussel Mytilus galloprovincialis

Cerium nanoparticles (nCeO2) are increasingly utilized in a wide variety of industrial, environmental and biomedical applications, and are therefore expected to be released in the aquatic environment. Due to its peculiar redox properties, nCeO2 may present unique hazards to environmental and human health. Previous data showed that in the hemocytes of the marine bivalve Mytilus galloprovincialis, in vitro exposure to a particular type of nCeO2 (9 nm, characterized by negative ζ-potential, high H2O2 scavenging capacity and Ce3+/Ce4+ surface ratio) reduced basal ROS production, lysosomal membrane stability and phagocytic activity in the presence of hemolymph serum; the effects observed were partly ascribed to the formation of a SOD-protein corona in the hemolymph.In this work, the in vivo effects of this type of nCeO2 were investigated in mussels exposed to 100 μg/L nCeO2 for 96 h; several lysosomal, immune, inflammatory and antioxidant biomarkers were measured at cellular (hemocytes) and tissue (gills, digestive gland) level. Molecular responses were evaluated in hemocytes and digestive gland by determining expression of 11 selected genes related to known biological functions. The results show specific immunomodulatory and antioxidant effects of nCeO2 at different levels of biological organization in the absence of Cerium tissue accumulation. These data further support the redox mechanisms at the basis of the physiological effects of nCeO2. Finally, in order to evaluate the possible impact at the whole organism level, the effects of nCeO2 were evaluated in the 48 h embryotoxicity assay in a wide concentration range. However, nCeO2 exposure resulted in a small reduction in normal embryo development. Overall, the results demonstrate that in mussels nCeO2 can selectively modulate different physiological processes at different levels of biological organization.

Inhibition of thioredoxin-dependent H2O2 removal sensitizes malignant B-cells to pharmacological ascorbate

L-ascorbate (L-ASC) is a widely-known dietary nutrient which holds promising potential in cancer therapy when given parenterally at high doses. The anticancer effects of L-ASC involve its autoxidation and generation of H2O2, which is selectively toxic to malignant cells. Here we present that thioredoxin antioxidant system plays a key role in the scavenging of extracellularly-generated H2O2 in malignant B-cells. We show that inhibition of peroxiredoxin 1, the enzyme that removes H2O2 in a thioredoxin system-dependent manner, increases the sensitivity of malignant B-cells to L-ASC. Moreover, we demonstrate that auranofin (AUR), the inhibitor of the thioredoxin system that is used as an antirheumatic drug, diminishes the H2O2-scavenging capacity of malignant B-cells and potentiates pharmacological ascorbate anticancer activity in vitro and in vivo. The addition of AUR to L-ASC-treated cells triggers the accumulation of H2O2 in the cells, which results in iron-dependent cytotoxicity. Importantly, the synergistic effects are observed at as low as 200 µM L-ASC concentrations. In conclusion, we observed strong, synergistic, cancer-selective interaction between L-ASC and auranofin. Since both of these agents are available in clinical practice, our findings support further investigations of the efficacy of pharmacological ascorbate in combination with auranofin in preclinical and clinical settings.

Ridge-furrow mulched with plastic film improves the anti-oxidative defence system and photosynthesis in leaves of winter wheat under deficit irrigation.

In semi-arid areas of China, the ridge-furrow mulched with plastic film (RF) cultivation system is a common water-saving agricultural technique where the shortage of water resources has become a serious problem. Therefore, we aimed to explore whether this cultivation is actually an improvement over the traditional flat planting (TF) method while testing two deficit irrigation (150, 75 mm) levels to grow winter wheat. Furthermore, we examined the responses of the anti-oxidative defence system and photosynthetic capacity of winter wheat flag leaves under three simulated rainfall (275, 200 and 125 mm) conditions. The results showed that the RF system with 150 mm deficit irrigation and 200 mm simulated rainfall condition (RF2150) treatment raised soil water content (%) at the jointing and flowering stages and achieved higher net photosynthesis rates (Pn) in flag leaves. Furthermore, such improvements were due to the reduction of malondialdehyde (MDA) content and oxidative damage during different growth stages of winter wheat. The RF2150 treatment significantly increased the activities of superoxide dismutase (SOD); peroxidise (POD), catalase (CAT) and ascorbate peroxidase (APX) and the content of soluble protein (SP) during different growth stages of winter wheat. Furthermore, RF2150 treatment attained the highest value at the flowering stage, while also exhibiting significant declines in contents of proline, MDA, H2O2 and O2 in flag leaves. The higher free H2O2 and O2 scavenging capacity and better anti-oxidative enzyme activities under the RF2150 treatment were due to the lower level of lipid peroxidation, which effectively protected the photosynthetic machinery. The net photosynthetic rate of flag leaves was positively correlated with SOD, POD, CAT, APX and SP activities, and negatively correlated with proline, MDA, H2O2 and O2 contents. We concluded that the RF2150 treatment was the better water-saving management strategy because it significantly delayed flag leaf senescence and caused the increases in SWC, WUE, Pn, antioxidant enzyme activities and grain yield of winter wheat grown in semi-arid regions of China.

The maize secondary metabolism glycosyltransferase UFGT2 modifies flavonols and contributes to plant acclimation to abiotic stresses

Nowadays, the plant family 1 glycosyltransferases (UGTs) are attracting more and more attention since members of this family can improve the properties of secondary metabolites and have significantly enriched the chemical species in plants. Over the past decade, most studies on UGTs have been conducted in Arabidopsis thaliana and they were proved to play diverse roles during the plant life cycle. The Zea mays (maize) GT1 family comprises a large number of UDP-glycosyltransferase (UGT) members. However, their enzyme activities and the biological functions are rarely revealed. In this study, a maize flavonol glycosyltransferase, UFGT2, is identified and its biological role is characterized in detail. The UFGT2 enzyme activity, the flavonol and glycoside levels in planta were examined by high- performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS). The functions of UFGT2 in modifying flavonols, mediating flavonol accumulation and improving stress tolerance were analysed using two ufgt2 mutants and transgenic arabidopsis plants. By in vitro enzyme assay, the maize UFGT2 was found to show strong activity towards two flavonols: kaemferol and quercetin. Two ufgt2 knockout mutants, Mu689 and Mu943, exhibited obvious sensitivity to salt and drought stresses. The endogenous quercetin and kaempferol glycosides, as well as the total flavonol levels were found to be substantially decreased in the two ufgt2 mutants, with declined H2O2-scavenging capacity. In contrast, ectopic expression of UFGT2 in arabidopsis led to increased flavonol contents and enhanced oxidative tolerance. Moreover, expression of typical stress-related genes in arabidopsis and maize were affected in UFGT2 overexpression plants or knockout mutants in response to abiotic stresses. UFGT2 was also transferred into the arabidopsis ugt78d2 mutant and it was found to recover the deficient flavonol glycoside pattern in the ugt78d2 mutant, which confirmed its catalysing activity in planta. It is demonstrated in our study that a maize glycosyltransferase, UFGT2, involved in modifying flavonols, contributes to improving plant tolerance to abiotic stresses.

Exogenous application of a low concentration of melatonin enhances salt tolerance in rapeseed (Brassica napus L.) seedlings

Melatonin is a naturally occurring compound in plants. Here, we tested the effect of exogenous melatonin on rapeseed (Brassica napus L.) grown under salt stress. Application of 30 µmol L−1 melatonin alleviated salt-induced growth inhibition, and the shoot fresh weight, the shoot dry weight, the root fresh weight, and the root dry weight of seedlings treated with exogenous melatonin increased by 128.2, 142.9, 122.2, and 124.2%, respectively, compared to those under salt stress. In addition, several physiological parameters were evaluated. The activities of antioxidant enzymes including peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were enhanced by 16.5, 19.3, and 14.2% compared to their activities in plants without exogenous melatonin application under salt stress, while the H2O2 content was decreased by 11.2% by exogenous melatonin. Furthermore, melatonin treatment promoted solute accumulation by increasing the contents of proline (26.8%), soluble sugars (15.1%) and proteins (58.8%). The results also suggested that higher concentrations (>50 µmol L−1) of melatonin could attenuate or even prevent the beneficial effects on seedling development. In conclusion, application of a low concentration of exogenous melatonin to rapeseed plants under salt stress can improve the H2O2-scavenging capacity by enhancing the activities of antioxidant enzymes such as POD, CAT and APX, and can also alleviate osmotic stress by promoting the accumulation of osmoregulatory substances such as soluble proteins, proline, and water soluble glucan. Ultimately, exogenous melatonin facilitates root development and improves the biomass of rapeseed seedlings grown under salt stress, thereby effectively alleviating the damage of salt stress in rapeseed seedlings.

Physiological effects of repeated foliar application of magnetite nanoparticles on maize plants

AbstractIron is an essential micronutrient which is highly unavailable for plants in calcareous soils. Although the application of nanoparticles (NPs) to plants has been recently implemented, their long‐term effects have not been studied yet. The objective of this study was to investigate whether the treatment of maize plants with 100 ppm iron nanoparticles (Fe‐NPs) through their life cycle would affect the development of the second generation. The plants were treated with or without 100 ppm of Fe‐NPs and 100 ppm of Fe‐Ch, and their seeds were planted to obtain the second generation. The latter were again treated with or without Fe‐NPs and Fe‐Ch, and the results of two generations were compared. In the first generation, Fe‐NPs treatments improved maize photosynthesis and hydrogen peroxide (H2O2) scavenging capacity and lowered the rate of membrane lipid peroxidation, compared to the control and Fe‐Ch‐treated plants. The improvement of calcium, Fe2+, total iron and ferritin contents was more pronounced in Fe‐NPs treatments. However, the second progeny of Fe‐NPs‐treated plants showed less biomass, lower contents of chlorophyll, protein and calcium, and lower H2O2 scavenging capacity but higher amount of total iron content, compared with the control group and the first generation. In comparison, no adverse effects on growth parameters were observed in the plants which were treated with Fe‐Ch for two subsequent generations, while their total iron and ferritin contents were remarkable. Due to the adverse effects of Fe‐NPs in the second generation, more caution in its application for consecutive years is recommended.

Redox homeostasis of breast cancer lineages contributes to differential cell death response to exogenous hydrogen peroxide

AimsCancer cells produce higher amounts of reactive oxygen species (ROS) than their normal counterparts. It has been suggested that a further increase in ROS concentration in these cells would lead to oxidative damage-driven death. Thus, we aimed to understand how the intra- and extracellular redox homeostasis differences set cell death response to ROS in breast cancer cell lines. Main methodsIntra- and extracellular ROS generation was evaluated in tumoral (MCF-7 and MDA-MB-231) and non-tumoral (MCF10A) breast epithelial cells, as well as H2O2 concentration in the culture medium, glutathione peroxidase (GPx), total superoxide dismutase (SOD) and catalase activities, extracellular H2O2 scavenging capacity and total thiol content. Cell viability was determined after H2O2 exposure using the MTT assay. Key findingsWe have found an increased extracellular ROS production in tumor cells when compared to the non-tumoral lineage. MCF10A cells had higher H2O2 concentration in the extracellular medium. Moreover, extracellular H2O2-scavenging activity was higher in MDA-MB-231 when compared to MCF10A and MCF-7. Regarding intracellular antioxidant activity, a lower GPx activity in tumor cell lines and a higher catalase activity in MDA-MB-231 were observed. Thiol content was lower in MDA-MB-231. Additionally, tumor cell lines were more sensitive to H2O2 exposure than the non-tumoral cells. SignificanceThe present report shows that the capability to generate and metabolize ROS differ greatly among the breast cancer cell lines, thus suggesting that redox balance is finely regulated during carcinogenesis. Therefore, our data suggest that therapeutic approaches targeting the redox status might be useful in the treatment of breast tumors.

THE EFFECT OF OSMOTIC STRESS ON ANTI-OXIDATIVE CAPACITY OF BLACK GRAM (VIGNA MUNGOL.)

SUMMARYIn order to assess the response of four popularly grown black gram (Vigna mungoL.) genotypes (T9, PU 19, USJD 113, KU 301) under osmotic stress, the present study was carried out by monitoring the changes in relative leaf water content (RLWC), carotenoid, total soluble protein (TSP), membrane lipid peroxidation (MDA), H2O2scavenging capacity, and the activities of superoxide dismutase (SOD) and catalase (CAT). Osmotic stress was applied by withholding irrigation for 15 consecutive days at vegetative, flowering and pod filling stages. Under stress condition, several fold increase in the content of MDA, H2O2scavenging activity and antioxidant enzyme activity was recorded while, RLWC, carotenoid and TSP were found to decrease. Flowering stage was found to be most sensitive in terms of economic yield. The genotype T9 experienced lowest reduction in yield (12.10–33.91%) with maximum value of drought tolerance index (DTI) (7.48) which can be attributed to its higher tolerance capacity to drought. On the other hand, USJD 113 had the highest yield loss (26.48–60.99%) and lowest DTI (6.07) value, indicating its susceptibility towards osmotic stress.

Mitochondrial specialization revealed by single muscle fiber proteomics: focus on the Krebs cycle.

We have developed a highly sensitive mass spectrometry-based proteomic workflow to examine the proteome of single muscle fibers. This study revealed significant differences in the mitochondrial proteome of the four major fiber types present in mouse skeletal muscle. Here, we focus on Krebs cycle enzymes and in particular on the differential distribution of the two mitochondrial isocitrate dehydrogenases, IDH2 and IDH3. Type 1/slow fibers contain high levels of IDH2 and relatively low levels of IDH3, whereas fast 2X and 2B fibers show an opposite expression pattern. The findings suggest that in skeletal muscle, IDH2 functions in the forward direction of the Krebs cycle and that substrate flux along the cycle occurs predominantly via IDH2 in type 1 fibers and via IDH3 in 2X and 2B fibers. IDH2-mediated conversion of isocitrate to α-ketoglutarate leads to the generation of NADPH, which is critical to buffering the H2O2 produced by the respiratory chain. Nicotinamide nucleotide transhydrogenase (NNT), the other major mitochondrial enzyme involved in NADPH generation, is also more abundant in type 1 fibers. We suggest that the continuously active type 1 fibers are endowed with a more efficient H2O2 scavenging capacity to cope with the higher levels of reactive oxygen species production.