Up-regulation Of Antioxidant Enzyme Activities Research Articles

Inter-subspecies diversity of maize to drought stress with physio-biochemical, enzymatic and molecular responses.

Drought is the most significant factor limiting maize production, given that maize is a crop with a high water demand. Therefore, studies investigating the mechanisms underlying the drought tolerance of maize are of great importance. There are no studies comparing drought tolerance among economically important subspecies of maize. This study aimed to reveal the differences between the physio-biochemical, enzymatic, and molecular mechanisms of drought tolerance in dent (Zea mays indentata), popcorn (Zea mays everta), and sugar (Zea mays saccharata) maize under control (no-stress), moderate, and severe drought stress. Three distinct irrigation regimes were employed to assess the impact of varying levels of drought stress on maize plants at the V14 growth stage. These included normal irrigation (80% field capacity), moderate drought (50% field capacity), and severe drought (30% field capacity). All plants were grown under controlled conditions. The following parameters were analyzed: leaf relative water content (RWC), loss of turgidity (LOT), proline (PRO) and soluble protein (SPR) contents, membrane durability index (MDI), malondialdehyde (MDA), and hydrogen peroxide (H2O2) content, the antioxidant enzyme activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT). Additionally, the expression of heat shock proteins (HSPs) was examined at the transcriptional and translational levels. The effects of severe drought were more pronounced in sugar maize, which had a relatively high loss of RWC and turgor, membrane damage, enzyme activities, and HSP90 gene expression. Dent maize, which is capable of maintaining its RWC and turgor in both moderate and severe droughts, and employs its defense mechanism effectively by maintaining antioxidant enzyme activities at a certain level despite less MDA and H2O2 accumulation, exhibited relatively high drought tolerance. Despite the high levels of MDA and H2O2 in popcorn maize, the up-regulation of antioxidant enzyme activities and HSP70 gene and protein expression indicated that the drought coping mechanism is activated. In particular, the positive correlation of HSP70 with PRO and HSP90 with enzyme activities is a significant result for studies examining the relationships between HSPs and other stress response systems. The discrepancies between the transcriptional and translational findings provide an opportunity for more comprehensive investigations into the role of HSPs in stress conditions.

SVHRSP Alleviates Age-Related Cognitive Deficiency by Reducing Oxidative Stress and Neuroinflammation.

Our previous studies have shown that scorpion venom heat-resistant synthesized peptide (SVHRSP) induces a significant extension in lifespan and improvements in age-related physiological functions in worms. However, the mechanism underlying the potential anti-aging effects of SVHRSP in mammals remains elusive. Following SVHRSP treatment in senescence-accelerated mouse resistant 1 (SAMR1) or senescence-accelerated mouse prone 8 (SAMP8) mice, behavioral tests were conducted and brain tissues were collected for morphological analysis, electrophysiology experiments, flow cytometry, and protein or gene expression. The human neuroblastoma cell line (SH-SY5Y) was subjected to H2O2 treatment in cell experiments, aiming to establish a cytotoxic model that mimics cellular senescence. This model was utilized to investigate the regulatory mechanisms underlying oxidative stress and neuroinflammation associated with age-related cognitive impairment mediated by SVHRSP. SVHRSP significantly ameliorated age-related cognitive decline, enhanced long-term potentiation, restored synaptic loss, and upregulated the expression of synaptic proteins, therefore indicating an improvement in synaptic plasticity. Moreover, SVHRSP demonstrated a decline in senescent markers, including SA-β-gal enzyme activity, P16, P21, SIRT1, and cell cycle arrest. The underlying mechanisms involve an upregulation of antioxidant enzyme activity and a reduction in oxidative stress-induced damage. Furthermore, SVHRSP regulated the nucleoplasmic distribution of NRF2 through the SIRT1-P53 pathway. Further investigation indicated a reduction in the expression of proinflammatory factors in the brain after SVHRSP treatment. SVHRSP attenuated neuroinflammation by regulating the NF-κB nucleoplasmic distribution and inhibiting microglial and astrocytic activation through the SIRT1-NF-κB pathway. Additionally, SVHRSP significantly augmented Nissl body count while suppressing neuronal loss. SVHRSP could remarkably improve cognitive deficiency by inhibiting oxidative stress and neuroinflammation, thus representing an effective strategy to improve brain health.

Effect of Salicylic Acid on the Growth and Development of Sweet Pepper (Capsicum annum L.) under Standard and High EC Nutrient Solution in Aeroponic Cultivation

High electrical conductivity (EC) in cultivation systems with the recirculating nutrient solutions can affect plant growth and development. This study aimed to investigate the effect of salicylic acid (SA) on the selected physiological and biochemical parameters of sweet pepper (Capsicum annum L.) growing aeroponically at standard and high concentrations of nutritive solutions. Four experimental variants were tested: (1) plants cultivated under low EC conditions, (2) plants cultivated under low EC conditions and treated with foliar SA, (3) plants cultivated under high EC conditions, (4) plants cultivated under high EC conditions and treated with SA on leaves and roots. The obtained results revealed that exogenous SA, regardless of EC, reduced the formation of fruits with calcium deficiency symptoms. Furthermore, SA helps plants to cope with high EC nutrient stress through an increase in leaf SPAD index, maximum light-adapted chlorophyll fluorescence and PSII viability. Exogenous SA reduced the number of soluble proteins both under low and high EC; however, increased H2O2 content induced a defence mechanism reflected by the upregulation of antioxidant enzyme activity. The results of the study provide valuable information on the role of SA in the alleviation of the harmful effect of salinity under aeroponic cultivation.

Selenium-containing polysaccharide from Spirulina platensis alleviates Cd-induced toxicity in mice by inhibiting liver inflammation mediated by gut microbiota.

Selenium-containing polysaccharide from Spirulina platensis (Se-SPP) has been demonstrated to help in inhibiting cadmium-induced injury in mice, but the underlying mechanism has not been determined. This study aimed to investigate the beneficial effects of Se-SPP on alleviating Cd-induced toxicity in mice by targeting liver inflammatory and gut microbiota. Se-SPP supplementation for 28 days in Cd-induced toxic mice significantly mitigated liver pathological damage and inflammation, which was correlated to the upregulation of antioxidant enzyme activity. Furthermore, Se-SPP effectively restored Cd-induced disruption of the intestinal barrier compared to model group, as indicated by the depletion of Muribaculaceae and the enrichment of Ruminococcaceae. Spearman's correlation analysis revealed that the Se-SPP-altered microbes were highly correlated with inflammation-related indexes in Cd-induced toxic mice. Noteworthily, the modulation of Se-SPP on the Ruminococcaceae population contributed to the improvement of Cd-induced inflammation-related diseases by downregulating the tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) in the liver. These findings suggested that Se-SPP may act as prebiotics for ameliorating Cd-induced toxicity in mice by inhibiting liver inflammation mediated by gut microbiota, and target-specific microbiota of Cd-induced inflammation-related diseases deserve further attention.

Effects of acute heat exposure on oxidative stress and antioxidant defenses in overwintering frogs, Nanorana parkeri

Climate warming is intensifying on the Tibetan Plateau and poses a serious threat to amphibians that live there. Although hibernation physiology and ecology of Nanorana parkeri, a frog species native to the Tibetan plateau, has been well studied, little information is available about the physiological and biochemical responses to acute rising temperature. Here, we conducted an acute warming experiment comparing hibernating N. parkeri (acclimated at 4 °C) and frogs acutely warmed to 10 °C for 12 h, comparing indicators of oxidative stress and antioxidant defense between the two groups. Acute warming led to a significant increase in the content of oxidized glutathione and the ratio of oxidized:reduced glutathione in liver and muscle, indicating that rapid warming causing oxidative stress could be a negative factor for frogs inhabiting the Tibetan plateau. Malondialdehyde content increased by 57% only in muscle but decreased significantly in three tissues. Protein carbonyl groups rose by 15% in brain, 28% in liver, and 21% in muscle after heat exposure but vitamin C content in heart decreased by 44%. Acute heat exposure also induced tissue-specific upregulation of antioxidant enzyme activities. Catalase activity increased by 27% in heat-exposed frogs, as compared to controls, and glutathione peroxidase activity rose by 12% in brain, 30% in liver, and 12% in muscle. Glutathione-S-transferase activity was also enhanced in heart and muscle of heat-exposed frogs. Acute warming also resulted in a rise in total antioxidant capacity in all tissues examined except kidney, relative to controls. In summary, our findings show that acute heat exposure to hibernating N. parkeri causes a tissue-specific increase in oxidative damage and antioxidant defenses, with skeletal muscle being the most affected tissue. These results reveal the physiological responses to acute temperature change in overwintering N. parkeri.

Growth, ROS accumulation site, and photosynthesis inhibition mechanism of Chlorella vulgaris by triclosan.

Although the addition of triclosan (TCS) in consumer products has been strictly restricted, its continuous applications in hospitals and other medical facilities and its numerous residues still pose a potential risk to aquatic organisms and aquatic ecosystems. In this study, we investigated the growth, biochemical alterations, and physiological responses of Chlorella vulgaris exposed to different concentrations of TCS. The potential toxicity mechanisms associated with excessive production of reactive oxygen species (ROS) and disruption of photosynthetic system II (PSII) were also analyzed. The results indicated that the growth, cellular ultrastructure, and physiology of C. vulgaris were severely affected by TCS in a dose-effect dependent manner. TCS inhibited the growth of C. vulgaris, leading to mitochondria enlargement, the disordering of the arrangement of thylakoids, cell wall rupture, organelles loss, and the cytoplasm lysis. TCS induced severe oxidative damage characterized by ROS accumulation, elevated malondialdehyde (MDA), and up-regulation of antioxidant enzyme activities. Moreover, in TCS-induced algal cells, the main sites of ROS accumulation were chloroplasts, mitochondria, and cell membranes, with ROS accumulating most in the mitochondria. In addition, TCS caused damage to the reaction center (RC inactivation), donor side (OEC damage), and accepted side (electron transport from QA to QB) of PSII in C. vulgaris, leading to inhibition of photosynthetic activity. These results could provide novel insights into the mechanisms of TCS-induced ROS accumulation and photosynthetic inhibition in C. vulgaris, which would contribute to a deep understanding of TCS toxicity on algae.

Sodium butyrate protects against oxidative stress in high-fat-diet-induced obese rats by promoting GSK-3β/Nrf2 signaling pathway and mitochondrial function.

Sodium butyrate (NaB), obtained by fermenting dietary fiber via intestinal microflora, was recently shown to improve the activity of some antioxidant enzymes in vivo. This study aims to investigate the term changes of mitochondrial energy metabolism and redox homeostasis in skeletal muscles and clarify the regulatory mechanism and dose effect of NaB on skeletal muscle. Male Sprague-Dawley rats were divided into the control group, obesity-prone (OP) group and obesity-resistant (OR) group based on the gain of body weight after 8 weeks' of feeding high-fat diet (HFD), followed by sacrificing rats at the end of 20th week. NaB intervention (12 weeks) could effectively reduce the body weight of rats in the OP and OR groups. NaB also mediated upregulation of antioxidant enzyme activity and GSH/GSSG ratio, while reducing reactive oxygen species (ROS) levels and malondialdehyde (MDA) content. At the molecular level, NaB upregulated Pi3k, Nrf2, Nqo-1, and Ho-1, but downregulated Gsk-3β mRNA expression by regulating the Nrf2 antioxidant pathway to enhance tissue antioxidant capacity. At the same time, NaB intervention significantly upregulated Glut4, Irs-1, Pdx1, and MafA, expression in gastrocnemius muscles of OP and OR rats, and elevated insulin secretion and muscle insulin sensitivity. Thus, NaB activates antioxidant pathway, improves the antioxidant capacity of obese rat tissues and promotes glucose metabolism. PRACTICAL APPLICATIONS: This study found that obesity-prone and obesity-resistant rats have differences in mitochondrial redox homeostasis and energy metabolism in tissues. Meanwhile, sodium butyrate can effectively promote muscle protein synthesis, increase insulin sensitivity, and promote glucose metabolism in obesity rats. Thus, sodium butyrate supplementation or increasing intestinal butyrate production (e.g., by consuming foods rich in dietary fiber) is a potential means of improving the body's glucose metabolism and obesity profile.

Salicylic Acid Priming Regulates Stomatal Conductance, Trichome Density and Improves Cadmium Stress Tolerance in Mentha arvensis L.

The application of phytohormones through seed priming could enhance quality of important medicinal and aromatic plants (MAPs) under heavy metal stress. We evaluated the potential of salicylic acid (SA) priming for overcoming the adverse effects of cadmium stress in Mentha arvensis L. plants. Suckers of plants were primed with SA before transplanting them into soil. At 30 days after transplanting, two doses (50 and 100 μm) of CdCl2 were applied to the soil. Both Cd treatments altered plant growth, photosynthetic pigments, leaf gas exchange attributes, and mineral nutrient contents. The 50 and 100 μm Cd treatments increased endogenous Cd content by 97.95 and 98.03%, electrolyte leakage (EL) by 34.21 and 44.38%, hydrogen peroxide (H2O2) by 34.71 and 55.80%, malondialdehyde (MDA) by 53.08 and 63.15%, and superoxide content (O2–•) by 24.07 and 38.43%, respectively. Cd triggered the up-regulation of antioxidant enzyme activities (superoxide dismutase, SOD; catalase, CAT; ascorbate peroxidase, APX; and glutathione reductase GR) and increased osmolyte biosynthesis and, interestingly, secondary metabolite (SM) accumulation. The presence of SA and Cd had an additive effect on these parameters. Nevertheless, plants primed with SA regulated stomatal conductance under Cd stress. SA priming to menthol mint plants under Cd stress overcome the effects of Cd stress while increasing SMs.

Photocatalytic inactivation and destruction of harmful microalgae Karenia mikimotoi under visible-light irradiation: Insights into physiological response and toxicity assessment

Harmful algal blooms (HABs) caused by Karenia mikimotoi have frequently happened in coastal waters worldwide, causing serious damages to marine ecosystems and economic losses. Photocatalysis has potential to in-situ inhibit algal growth using sustainable sunlight. However, the inactivation and detoxification mechanisms of microalgae in marine environment have not been systematically investigated. In this work, for the first time, visible-light-driven photocatalytic inactivation of K. mikimotoi was attempted using g-C3N4/TiO2 immobilized films as a model photocatalyst. The inactivation efficiency could reach 64% within 60 min, evaluated by real-time in vivo chlorophyll-a fluorometric method. The immobilized photocatalyst films also exhibited excellent photo-stability and recyclability. Mechanisms study indicated photo-generated h+ and 1O2 were the dominant reactive species. Algal cell rupture process was monitored by fluorescent microscope combined with SEM observation, which confirmed the damage of cell membrane followed by the leakage of the intracellular components including the entire cell nucleus. The physiological responses regarding up-regulation of antioxidant enzyme activity (i.e. CAT and SOD), intracellular ROSs level and lipid peroxidation were all observed. Moreover, the intracellular release profile and acute toxicity assessment indicated the toxic K. mikimotoi was successfully detoxified, and the released organic matter had no cytotoxicity. This work not only provides a potential new strategy for in-situ treatment of K. mikimotoi using sunlight at sea environments, but also creates avenue for understanding the inactivation and destruction mechanisms of marine microalgae treated by photocatalysis and the toxicity impacts on the marine environments.

Antioxidant effects of lebanese Crocus sativus L. and its main components, crocin and safranal, on human skeletal muscle cells

Introduction- Crocus sativus L. (C. sativus L.) has gained interest as a potential source of pharmacologically bioactive compounds and is believed to possess antioxidant properties. This study used human myoblast cells to evaluate the protective effects of C. sativus L. extracts, (crocin, and safranal) on hydrogen peroxide (H2O2)-induced oxidative stress using human myoblast cells. Methods- HPLC was used to detect the presence of the active compounds safranal/crocin in the Lebanese C. sativus L. extracts. Their cellular antioxidant property was examined by trypan blue, cell adhesion, immunostaining and cell cycle assays. Transcriptional expression and activities of SOD1/2, GPX1, and catalase were also determined. The ability of C. sativus L. and its main components to modulate myogenic regulatory factors (MyoD, Myf5) was evaluated using RT-PCR assay. Results- The water/methanol (50:50, v/v) extract of C. sativus L. stigmas were found to contain safranal and crocin, with a high concentration of trans-crocin 3/4 in particular. In vitro, pretreatment (24 h) with safranal exhibited the lowest antioxidant effect whereas pretreatment with C. sativus L. extracts (0.3 µg/ml) and more notably with crocin (0.3 µM) attenuated the toxic impact of H2O2 (50 µM, 24 h) and also restored the capacity of adhesion among LHCN-M2 cells. This protective effect was associated with both a reduction of intracellular reactive oxygen species generation and an up-regulation of antioxidant enzyme activities. Furthermore, crocin pretreatment significantly improved the transcriptional expression of myogenic regulatory genes. Conclusion- C. sativus L., particularly its main component crocin, was shown to have therapeutic potential against oxidative stress-associated skeletal muscle diseases.

Identification of Six Flavonoids as Novel Cellular Antioxidants and Their Structure-Activity Relationship.

This study is aimed at determining the relationship of flavonoid structures to their chemical and intracellular antioxidant activities. The antioxidant activities of 60 flavonoids were investigated by three different antioxidant assays, including 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, oxygen radical absorption capacity (ORAC), and cellular antioxidant activity (CAA) assays. The result showed 6 flavonoids as good cellular antioxidants evaluated for the first time. The cellular antioxidant activities of compounds 7-methoxy-quercetin, 3-O-methylquercetin, 8-hydroxy-kaempferol, quercetin-3-O-α-arabinofuranose, kaempferol-7-O-glucopyranoside, and luteolin6-C-glucoside were linked with the upregulation of antioxidant enzyme activities (superoxide dismutase, catalase, and glutathione peroxidase). A structure-activity relationship suggested that 2,3-double bond, 4-keto groups, 3′,4′-catechol structure, and 3-hydroxyl in the flavonoid skeleton played important roles in the antioxidant behavior. Furthermore, the cell proliferative assay revealed a low cytotoxicity for 3-O-methylquercetin. The present results provide valuable information for the dietary application of flavonoids with different structures for high antioxidant.

Comprehensive genomic and proteomic profiling reveal Acinetobacter johnsonii JH7 responses to Sb(III) toxicity

Antimony (Sb) pollution poses a severe health threat to ecosystems. However, the toxic effects of Sb on biota are far from being elucidated. One of the unresolved questions is the molecular signal pathways underlying microbial adaptation to excess antimonite or Sb(III) exposure. The response of a Sb(III)-resistant bacterium Acinetobacter. johnsonii JH7 to Sb(III) stress was investigated using genomic and proteomic profiling. Sb(III) induced the formation of reactive oxygen species thereby leading to oxidative stress and the up-regulation of antioxidant enzyme activities. In addition, two important operons (ars and pst) playing critical roles in this cellular response were identified. The ars proteins functioned cooperatively to expel Sb(III) thereby decreasing antimonite toxicity. Downregulation of the phosphate-specific transporter might reduce the uptake of Sb(V) while hindering phosphorus assimilation. Interaction of Sb(III) with JH7 strain cells also affected peptide syntheses and folding, energy conversion, and stability of the cellular envelope. The present study provides for the first time a global map of cellular adaptation to excess Sb(III). Such information is potentially useful to future Sb pollution remediation strategies.

Role of iron–lysine on morpho-physiological traits and combating chromium toxicity in rapeseed (Brassica napus L.) plants irrigated with different levels of tannery wastewater

Chromium (Cr) is among the most widespread toxic trace elements found in agricultural soils resulting from various anthropogenic activities. However, the role of micronutrient-amino acid chelates in reducing Cr toxicity in crop plants has recently been suggested. The present study was conducted to explore the effect of iron (Fe) chelated with lysine (lys) on plant growth, biomass, gaseous exchange attributes, oxidative stress indicators, antioxidant response, and Cr uptake in rapeseed (Brassica napus L.) plants irrigated with different levels of tannery wastewater in soil collected from District Kasur of Pakistan. B. napus seedlings (thirty-day-old) were shifted to pots irrigated with different levels of tannery wastewater. After two weeks, foliar application of Fe–lys (5 mM) was carried out for four successive weeks, and plants were harvested carefully post ten weeks of cultivation in tannery wastewater, under controlled conditions. Toxic levels of Cr in the soil significantly decreased plant height, fresh biomass of roots and leaves, dry biomass of roots and leaves, root length, number of leaves, leaf area, total chlorophyll contents, carotenoid contents, transpiration rate (E), stomatal conductance (gs), net photosynthesis (PN), and water use efficiency (WUE). Toxic Cr levels in the soil also increased oxidative stress in the roots and leaves of B. napus plants, which were overcome by the activities of various antioxidant enzymes, such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX). Moreover, increasing levels of Cr in the soil caused a significant increase in the Cr content of the roots and shoots of B. napus plants. The negative effects of Cr toxicity could be overturned by Fe–lys application, significantly increasing plant growth, biomass, chlorophyll content, and gaseous exchange attributes by reducing oxidative stress (H2O2, MDA, EL) and enhancing antioxidant enzyme activities. Furthermore, foliar application of Fe–lys reduced the Cr concentration and increased essential micronutrients (Fe contents) in the roots and shoots of B. napus plants. These results shed light on the effectiveness of Fe–lys in improving the growth and up-regulation of antioxidant enzyme activities of B. napus in response to Cr stress. However, further studies at field levels are required to explore the mechanisms of Fe–lys-mediated reduction of the toxicity of not only Cr, but possibly also other heavy metals in plants.

Mechanisms of trehalose-mediated mitigation of Cd toxicity in rice seedlings

Trehalose (TR) functions as a compatible solute and plays an important physiological role in osmotic protection, thereby enhancing the tolerance of plants to the adverse effects of abiotic stress. Currently, however, there is limited information available regarding the TR-mediated mitigation of stress related to potentially toxic metals in plants. In this study, experiments were conducted to determine the effect of TR on the growth status of rice seedlings, changes in oxidative stress markers, and Cadmium (Cd) absorption in response to Cd stress. Plants were subjected to single Cd, single TR, and combined Cd and TR treatments, and the effects on biomass, Cd uptake, and selected physiological indices including reactive oxygen species (ROS) levels and antioxidant enzyme activities were examined to elucidate the protective mechanisms of TR. It was found that Cd had a concentration-dependent inhibitory effect on rice biomass production, whereas single TR treatment had only a limited effect on the biomass of rice. A remarkable decrease in chlorophyll a and b content was observed during Cd treatment, up to 21.5% and 29.0%, respectively, which improved after exogenous TR was applied. Furthermore, compared to that of Cd treatment alone, TR could effectively reduce the content of stress-related oxidants (H2O2 and O2·-) and lower the upregulation of antioxidant enzyme activity, conditions that are more conducive to the growth of rice. Given that plants can degrade excess TR by increasing the activity of trehalase, exogenous TR application has limited effects on the normal physiology of plants. The uptake of Cd by rice was considerably lower (between 30% and 70%) than that of the control group when plants were cotreated with TR. Lower pH levels tend to promote Cd absorption in rice, and the addition of TR protects rice plants mainly via the considerable reduction in Cd concentration in the shoots and roots. Moreover, it was found that the stress-related effects of Cd on rice were closely related to the prevailing form of Cd in the culture medium. When Cd and TR are added simultaneously in a quantum chemical simulation, Cd occurs primarily as a Cd-TR chelate, which effectively reduces its mobility in and toxicity to rice. TR application thus represents a potential means of mitigating Cd toxicity in plants.

Biochemical and physiological impacts of zinc sulphate, potassium phosphite and hydrogen sulphide in mitigating stress conditions in soybean.

Soybean is the most widely grown oilseed in the world. It is an important source of protein and oil which are derived from its seeds. Drought stress is a major constraint to soybean yields. Finding alternative methods to mitigate the water stress for soybean is useful to maintain adequate crop yields. The aim of this study was to evaluate the morpho-physiological, biochemical and metabolic changes in soybean plants in two ontogenetic stages, under exposure to water deficit and treatment with zinc sulphate (ZS), potassium phosphite (PP) or hydrogen sulphide (HS). We carried out two independent experiments in the V4 and R1 development stages consisting of the following treatments: well-watered control (WW, 100% maximum water holding capacity, MWHC), water deficit (WD, 50% MWHC), PP + WW, PP + WD, HS + WW, HS + WD, ZS + WW and ZS + WD. The experimental design consisted of randomized blocks with eight treatments with five replicates. Morphological, physiological and metabolic analyses were performed 8 days after the start of the treatments for both experiments. We identified two tolerance mechanisms acting in response to compound application during water stress: the first involved the upregulation of antioxidant enzyme activity and the second involved the accumulation of soluble sugars, free amino acids and proline to facilitate osmotic adjustment. Both mechanisms are related to the maintenance of the photosynthetic parameters and cell membrane integrity. This report suggests the potential agricultural use of these compounds to mitigate drought effects in soybean plants.

Calcitriol protects the Blood-Brain Barrier integrity against ischemic stroke and reduces vasogenic brain edema via antioxidant and antiapoptotic actions in rats

BackgroundVasogenic brain edema is the most important complication of ischemic stroke that aggravates primary brain injury. Ischemia-Reperfusion (IR)-induced Blood-Brain Barrier (BBB) impairment limits the use of recombinant tissue plasminogen activator (r-tPA) by increasing the possibility of hemorrhagic transformation and contributing to vasogenic edema and neuroinflammation. This study examined the effects of post-ischemic treatment with calcitriol on cerebral infarction, vasogenic edema formation and BBB disruption in a rat model of ischemic stroke. MethodsMale Sprague-Dawley rats were divided into three main groups, including the sham, IR + vehicle and IR + calcitriol groups. Transient focal cerebral ischemia was induced by a 60-min-long occlusion of the left middle cerebral artery. The infarct volume, brain edema, BBB permeability and antioxidant enzyme activities were evaluated 24 h after ischemia. Immunohistochemical analysis was conducted to investigate cell apoptosis and Brain-Derived Neurotrophic Factor (BDNF) protein expression five days after ischemia. ResultsCompared to the IR + vehicle group, the IR + calcitriol group showed a reduced brain infarction volume, attenuated brain edema formation and improved BBB function. These protective effects were followed by the upregulation of antioxidant enzyme activities in the brain tissue. Additionally, a diminished cell apoptosis and an increased BDNF immunoreactivity were obtained in the IR + calcitriol group. ConclusionCalcitriol may reduce brain injury and attenuate vasogenic edema by upregulating antioxidant enzymes activities, reducing cell apoptosis and increasing BDNF protein in the brain tissue in a rat model of ischemic stroke.

Necrotrophic fungus Macrophomina phaseolina tolerates chromium stress through regulating antioxidant enzymes and genes expression (MSN1 and MT).

Cr(VI) tolerance level of phytopathogenic fungus viz., Macrophomina phaseolina (Tassi) Goid was assessed through growth, morphological, physiological, and metal accumulation assays. Initially, the fungus growth assays indicated that the fungus can grow over concentration range of 20-3000ppm and exhibited high tolerance index (0.88-1.00) and minimum inhibitory concentration at 3500ppm of Cr. Observations under compound and scanning electron microscope un-revealed the structural features of hyphae under Cr stress as thick-walled,aggregated, branched, short and broken, along with attachment of irregular objects on them. Metal accumulation analysis revealed reduction in Cr(VI) accumulation by the fungus with increase in metal concentration in the growth medium (500-3000ppm). Cr stress induced upregulation of antioxidant enzyme activities (catalase, peroxidase andpolyphenol oxidase), expression of genes (MSN1 and metallothionein) and appearnace ofnew protein bands suggesting the possible role in protection and survival of M. phaseolina against Cr(VI)-induced oxidative stress. This study concludes that interference of Cr with growth and physiological process of M. phaseolina could affect its infection level on its host plant, therefore, synergistic action of two factors needs to be addressed, which may aid to guide future research efforts in understanding impact of plant-pathogen-heavy metal interaction.

Long-term exposure to crotonaldehyde causes heart and kidney dysfunction through induction of inflammatory and oxidative damage in male Wistar rats

Crotonaldehyde is a ubiquitous hazardous pollutant, present in cigarette smoke and automobile exhaust and is endogenously generated by lipid peroxidation. Most of the current studies focus on its lung toxicity. However, there have been few investigations on the cardiac and renal toxicity caused by crotonaldehyde exposure. We hypothesized that oral intake of crotonaldehyde can cause inflammatory and oxidative/nitrosative damage to the heart and kidneys. Therefore, we treated male rats with crotonaldehyde by gavage at 0, 2.5, 4.5, and 8.5 mg/kg/day for 120 d and evaluated the alterations in histological and serological parameters, oxidative state, and inflammation responses to explore the roles of crotonaldehyde-induced oxidative/nitrosative stress and inflammation in the heart and kidney dysfunction and to explore the relationship between heart and kidney dysfunction. We found that body weight increment, as well as heart and kidney coefficients decreased with an increasing crotonaldehyde dosage. Histological examinations indicated that crotonaldehyde exposure led to focal myocardial necrosis, cardiac fibrosis, renal tubular epithelial cell edema, and renal lymphocyte infiltration. We also assessed the impact of crotonaldehyde treatment on oxidative/nitrosative stress markers, antioxidant enzymes, inflammatory biomarkers, heart/kidney functional markers, and angiotensin II-aldosterone-brain natriuretic peptide (AngII-ALD-BNP) levels. Overall, we found that proinflammatory cytokine and malondialdehyde levels increased in a dose-dependent manner. Furthermore, crotonaldehyde treatment (4.5 and 8.5 mg/kg) significantly prevented the upregulation of antioxidant enzyme activity, thereby increasing oxidative/nitrosative stress (p < 0.05). Moreover, we found that the levels of AngII and ALD increased, whereas the levels of BNP decreased, consistent with heart and kidney dysfunction. Collectively, these results suggest that long-term, low-dose crotonaldehyde exposure leads to an imbalance in AngII-ALD-BNP levels, which mediates cardiac hemodynamic changes causing internal oxidative/nitrosative stress and inflammatory reactions, leading to renal and cardiac dysfunction in male rats.

5-Aminolevulinic Acid Improves Nutrient Uptake and Endogenous Hormone Accumulation, Enhancing Low-Temperature Stress Tolerance in Cucumbers.

5-aminolevulinic acid (ALA) increases plant tolerance to low-temperature stress, but the physiological and biochemical mechanisms that underlie its effects are not fully understood. To investigate them, cucumber seedlings were treated with different ALA concentrations (0, 15, 30 and 45 mg/L ALA) and subjected to low temperatures (12/8 °C day/night temperature). The another group (RT; regular temperature) was exposed to normal temperature (28/18 °C day/night temperature). Low-temperature stress decreased plant height, root length, leaf area, dry mass accumulation and the strong seedling index (SSI), chlorophyll contents, photosynthesis, leaf and root nutrient contents, antioxidant enzymatic activities, and hormone accumulation. Exogenous ALA application significantly alleviated the inhibition of seedling growth and increased plant height, root length, hypocotyl diameter, leaf area, and dry mass accumulation under low-temperature stress. Moreover, ALA increased chlorophyll content (Chl a, Chl b, Chl a+b, and Carotenoids) and photosynthetic capacity, net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), and transpiration rate (Tr), as well as the activities of superoxide dismutase (SOD), peroxidase (POD, catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) enzymes, while decreasing hydrogen peroxide (H2O2), superoxide (O2•−), and malondialdehyde (MDA) contents under low-temperature stress. In addition, nutrient contents (N, P, K, Mg, Ca, Cu, Fe, Mn, and Zn) and endogenous hormones (JA, IAA, BR, iPA, and ZR) were enhanced in roots and leaves, and GA4 and ABA were decreased. Our results suggest the up-regulation of antioxidant enzyme activities, nutrient contents, and hormone accumulation with the application of ALA increases tolerance to low-temperature stress, leading to improved cucumber seedling performance.

Investigation of arsenic accumulation and biochemical response of in vitro developed Vetiveria zizanoides plants

Vetiver grass (Vetiveria zizanoides L. Nash) is found to be a suitable candidate for the phytoremediation of heavy metals. An investigation of arsenic (As) accumulation, translocation and tolerance was conducted in V. zizanoides plantlets upon exposure to different concentrations of arsenic (10, 50, 100 and 200µM) for 7 and 14 d. V. zizanoides plants were found effective in remediation of As, maximum being at 200µM after 14 d of exposure. The results of TBARS and photosynthetic pigments demonstrated that plants did not experience significant toxicity at all the concentrations of As after 7 days, however an increase in their level was found after 14 d. The up-regulation of antioxidant enzyme activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), catalase (CAT) and glutathione s-transferase (GST) in a coordinated and complementary manner enhanced tolerance to plants against arsenic induced oxidative stress. Taken together, the results indicated that in vitro developed plants of V. zizanoides have the potential to remediate and tolerate varying levels of As.