Lower Peroxidase Research Articles

Increased Catalase Activity and Maintenance of Photosystem II Distinguishes High-Yield Mutants From Low-Yield Mutants of Rice var. Nagina22 Under Low-Phosphorus Stress.

An upland rice variety, Nagina22 (N22) and its 137 ethyl methanesulfonate (EMS)-induced mutants, along with a sensitive variety, Jaya, was screened both in low phosphorus (P) field (Olsen P 1.8) and in normal field (Olsen P 24) during dry season. Based on the grain yield (YLD) of plants in normal field and plants in low P field, 27 gain of function (high-YLD represented as hy) and 9 loss of function (low-YLD represented as ly) mutants were selected and compared with N22 for physiological and genotyping studies. In low P field, hy mutants showed higher P concentration in roots, leaves, grains, and in the whole plant than in ly mutants at harvest. In low P conditions, Fv/Fm and qN were 24% higher in hy mutants than in ly mutants. In comparison with ly mutants, the superoxide dismutase (SOD) activity in the roots and leaves of hy mutants in low P fields was 9% and 41% higher at the vegetative stage, respectively, but 51% and 14% lower in the roots and leaves at the reproductive stage, respectively. However, in comparison with ly mutants, the catalase (CAT) activity in the roots and leaves of hy mutants in low P fields was 35% higher at the vegetative stage and 15% and 17% higher at the reproductive stage, respectively. Similarly, hy mutants in low P field showed 20% and 80% higher peroxidase (POD) activity in the roots and leaves at the vegetative stage, respectively, but showed 14% and 16% lower POD activity at the reproductive stage in the roots and leaves, respectively. Marker trait association analysis using 48 simple sequence repeat (SSR) markers and 10 Pup1 gene markers showed that RM3648 and RM451 in chromosome 4 were significantly associated with grain YLD, tiller number (TN), SOD, and POD activities in both the roots and leaves in low P conditions only. Similarly, RM3334 and RM6300 in chromosome 5 were associated with CAT activity in leaves in low P conditions. Notably, grain YLD was positively and significantly correlated with CAT activity in the roots and shoots, Fv/Fm and qN in low P conditions, and the shoots’ P concentration and qN in normal conditions. Furthermore, CAT activity in shoots was positively and significantly correlated with TN in both low P and normal conditions. Thus, chromosomal regions and physiological traits that have a role in imparting tolerance to low P in the field were identified.

Effect of the taxonomic group of fungi and type of substrate on the antioxidant activity of a solid-state fermentation system.

The enzymatic and non-enzymatic antioxidant activities of a solid-state fermentation system (SSFS) employing six basidiomycete and four ascomycete fungi on orange peel have been evaluated. Class comparisons revealed highly significant effect of fungal group on the antioxidant activity. Peroxidase activity appeared only in the basidiomycete fungi (particularly Pleurotus columbinus, Ganoderma resinaceum, and Pleurotus floridanus) whereas catalase activity appeared in the two fungal groups in favor of the ascomycetes (particularly Paecilomyces variotii and Aspergillus fumigatus). Maximal peroxidase and minimal catalase activities were found at moderate phenolic content, with extreme phenolic levels leading to low peroxidase activity but high catalase activity. Production of the non-enzymatic antioxidants (phenolics, flavonoids, reducing power, and DPPH scavenging) was in favor of the ascomycetes, which showed great native ability to synthesize flavonoids and also to release flavonoids from orange peel. The basidiomycete fungi, which have limited native ability to produce phenolics, had high ability to consume orange peel phenolics. By contrast, the ascomycete fungi exhibitedgreat native ability for production of phenolics and low ability to consume exogenous phenolics.

Physiopathological responses of sole (Solea senegalensis) subjected to bacterial infection and handling stress after probiotic treatment with autochthonous bacteria

This study aimed to evaluate the protective effects of four autochthonous bacteria isolated from juvenile sole (Solea senegalensis) intestine as dietary probiotic supplement against bacterial pathogen infection and handling/transport stressors. Growth performance and immune responses were evaluated after 85 days of feeding trial. Sole (IBW = 16.07 ± 0.11 g) were fed six experimental diets, a control diet (CTRL, without the dietary probiotic supplementation), and five diets supplemented with probiotic bacteria: PB1 (Shewanella hafniensis), PB2 (Enterococcus raffinosus), PB3 (Shewanella hafniensis + Arthrobacter soli), PB4 (Pseudomonas protegens + Arthrobacter soli) and PB5 (Shewanella hafniensis + Arthrobacter soli + Enterococcus raffinosus). All bacteria were selected based on their in vitro antimicrobial activity. After the growth trial, fish were submitted to a stress factor (transport) and then each dietary group was divided in two additional groups: non-infected (placebo) and infected with Photobacterium damselae subsp. piscicida. Immune and antioxidant responses were evaluated at day 10 post-infection. In infection trial A, fish were infected on the same day of transport, whereas in trial B fish were infected after a 7-day recovery from the transport stress. At the end of the feeding trial, fish fed with PB2 and PB4 showed lower final body weight when compared with the other dietary groups. Respiratory burst activity and nitric oxide production were not affected by probiotic supplementation. Fish fed with PB5 presented lower peroxidase activity compared to CTRL. Lysozyme and alternative complement pathway activity (ACH50) showed no significant differences between treatments. The innate immune responses were significantly affected after handling stress and bacterial infection. In trial A, the ACH50 levels of infected fish were significantly lower than the placebo groups. On the other hand, in trial B fish infected with Pdp demonstrated higher ACH50 levels when compared to placebos. Peroxidase levels were strongly modulated by bacterial infection and handling stress. In trials A and B, infection had a clear downgrade effect in peroxidase levels. Lipid peroxidation, catalase, glutathione S-transferase and glutathione reductase were altered by both bacterial infection and transport.Overall, dietary probiotic supplementation did not influence growth performance of sole. The immune and oxidative defenses of sole responded differently to infection depending on the probiotic and the synergy between pathogen infection and transport.

Improving bioconversion of eugenol to coniferyl alcohol by in situ eliminating harmful H2O2

Coniferyl alcohol is a valuable chemical. However, the current approaches to obtain coniferyl alcohol are either unefficient or expensive. Penicillium simplicissimum vanillyl alcohol oxidase (PsVAO) can be used to produce coniferyl alcohol. However, PsVAO intrinsically produces harmful byproduct H2O2. Utilizing catalase to decompose H2O2 is a potential straightforward approach; however, catalase can also exhibit peroxidase activity to facilitate coniferyl alcohol over-oxidation. In this study, catalases exhibiting both high catalase activity and low peroxidase activity were found out, and introduced into the bioconversion systems. Our results showed that eliminating H2O2in situ released H2O2 inhibition of PsVAO, improved coniferyl alcohol production and eliminated coniferyl alcohol over-oxidation. Finally, coniferyl alcohol titer, molar yield, and productivity reached 22.9 g/L, 78.7%, and 0.5 g/(L × h) respectively. An efficient coniferyl alcohol production method was developed by overcoming the intrinsic disadvantages of PsVAO.

Characterization of physico-chemical and bio-chemical compositions of selected four strawberry cultivars

The physico-chemical and bio-chemical compositions of Hongyan, Tiangxiang, Tongzi Ι and Zhangji strawberries inChinawere analyzed. Their values were pH 3.42~3.73, titration acidity 0.63~0.79%, total soluble sugars 5.26~8.95 g/100 gfresh weight (FW), ascorbic acid 21.38~42.89 mg/100 gFW, total phenolics 235.12~444.73 mg/100 gFW, pectin 82.84~96.13 mg/100 gFW, total organic acids 874.30~1216.27 mg/100 gFW, Individual phenolic compounds other than anthocyanins 7.60~12.18 mg/100 gFW, free amino acids 13.35~32.66 mg/100 gFW, monomeric anthocyanins 4.47~47.19 mg/100gFW, antioxidant capacity of ·DPPH 14.14~18.87 and FRAP 7.97~10.54 equal to mg/100 gVc, polyphenol oxidase (PPO) activity 0~0.42 Abs/min, peroxidase (POD) activity 0.17~0.34 Abs/min and pectin methyl esterase (PME) activity 0.012~0.018 mL/min. Tongzi Ι was most suitable for food processing due to the highest titration acidity, total phenolics, pectin, total organic acids, monomeric anthocyanins, antioxidant capacity of ·DPPH and FRAP with lower PPO, POD and PME activity.

Screening wild and cultivated cucurbits against root knot nematode to exploit as rootstocks for grafting in cucumber

Yield of mono-cropped cucumber (Cucumis sativus L.) is reduced by root knot nematode (Meloidogyne incognita Kofoid and White). Use of resistant rootstocks in grafting may overcome the problem. Cucurbitaceous species were screened against root knot nematode to evaluate their use as rootstocks in grafting. Inoculation was with nematodes @ 2 J2·g-1 (J2 = second stage juvenile) of soil in pot culture at the 1 to 2 true leaf stage, 45 days after inoculation, plants were uprooted and observations made to calculate Root Knot Nematode Index (RKI). Cucurbita moschata, Cucumis metuliferus, Citrullus colocynthis and Cucumis callosus were resistant having a RKI-2. Cucurbita ficifolia, Cucurbita maxima, Cucumis melo sub sp. agrestis were moderately resistant with a RKI-3. Total phenols content in roots indicates plant resistance to M. incognita. Cucumis metuliferus had the highest mean total phenols content (16.98 mg·g- 1 of root) followed by Citrullus colocynthis (16.08 mg·g-1 of root) and Cucurbita moschata (15.37mg·g-1 of root). Resistant rootstocks possessed higher peroxidase and PPO activity than susceptible ones. Cucumis metuliferus had the highest value of peroxidase and PPO activity (3.83 OD·min-1·g-1 of root and 3.67 OD·min-1·g-1 of root) followed by Citrullus colocynthis (3.26 and 3.63 OD·min-1·g-1 of root), Cucumis callosus (3.02 and 2.98 OD·min-1·g-1 of root) and Cucurbita moschata (2.93 and 2.94 OD·min-1·g-1 of root). Cucumber scions, ‘Green Long’ and ‘NS 408’ had lower peroxidase and PPO activity of 0.64 and 1.42 OD·min-1·g-1 and 0.57 and 1.31 OD·min- 1·g-1 of root, respectively. Resistant and moderately resistant cucurbitaceous species may be used for further studies possibly leading to improved yield.

Screening wild and cultivated cucurbits against root knot nematode to exploit as rootstocks for grafting in cucumber

Yield of mono-cropped cucumber (Cucumis sativus L.) is reduced by root knot nematode (Meloidogyne incognita Kofoid and White). Use of resistant rootstocks in grafting may overcome the problem. Cucurbitaceous species were screened against root knot nematode to evaluate their use as rootstocks in grafting. Inoculation was with nematodes @ 2 J2·g-1 (J2 = second stage juvenile) of soil in pot culture at the 1 to 2 true leaf stage, 45 days after inoculation, plants were uprooted and observations made to calculate Root Knot Nematode Index (RKI). Cucurbita moschata, Cucumis metuliferus, Citrullus colocynthis and Cucumis callosus were resistant having a RKI-2. Cucurbita ficifolia, Cucurbita maxima, Cucumis melo sub sp. agrestis were moderately resistant with a RKI-3. Total phenols content in roots indicates plant resistance to M. incognita. Cucumis metuliferus had the highest mean total phenols content (16.98 mg·g- 1 of root) followed by Citrullus colocynthis (16.08 mg·g-1 of root) and Cucurbita moschata (15.37mg·g-1 of root). Resistant rootstocks possessed higher peroxidase and PPO activity than susceptible ones. Cucumis metuliferus had the highest value of peroxidase and PPO activity (3.83 OD·min-1·g-1 of root and 3.67 OD·min-1·g-1 of root) followed by Citrullus colocynthis (3.26 and 3.63 OD·min-1·g-1 of root), Cucumis callosus (3.02 and 2.98 OD·min-1·g-1 of root) and Cucurbita moschata (2.93 and 2.94 OD·min-1·g-1 of root). Cucumber scions, ‘Green Long’ and ‘NS 408’ had lower peroxidase and PPO activity of 0.64 and 1.42 OD·min-1·g-1 and 0.57 and 1.31 OD·min- 1·g-1 of root, respectively. Resistant and moderately resistant cucurbitaceous species may be used for further studies possibly leading to improved yield.

English

Zizyphus spina-christi L. is one of the wide varieties of plant grown in Al-Ahsa Oasis in Saudi Arabia and known locally as Alnabaq (buckthorn). The objective of this investigation was to study the effects of postharvest calcium chloride applications on fruit quality of buckthorn under cold storage condition at 2°C and 90% RH for 5 weeks.¬¬ Fruits were dipped in calcium chloride at different concentrations (0, 2 and 4% W/V) for 10 min. Weight loss, total soluble solids (TSS), ascorbic acid content, fruit firmness and peroxidase activity were determined after Ca++ treatment and during cold storage every one week. The results revealed that, both the storage periods and treatments significantly affected the postharvest quality of Alnabaq fruits during cold storage condition. A reduction in fruit firmness and ascorbic acid content was observed during storage period. In addition, the results showed that, fruit treated with calcium chloride recorded higher firmness than the control, while lower peroxidase activity was recorded during cold storage at 2°C for 5 weeks. Generally, these results indicated that post-harvest Ca treatments delayed fruit softening and decreased weight loss. Key words: Storage, Ziziphus spina-christi, weight loss, firmness, CaCl2, peroxidase activity, ascorbic acid.

Humanlike substitutions to Ω-loop D of yeast iso-1-cytochrome c only modestly affect dynamics and peroxidase activity

Structural studies of yeast iso-1-cytochrome c (L.J. McClelland, T.-C. Mou, M.E. Jeakins-Cooley, S.R. Sprang, B.E. Bowler, Proc. Natl. Acad. Sci. U.S.A. 111 (2014) 6648–6653) show that modest movement of Ω-loop D (residues 70–85, average RMSD versus the native structure: 0.81 Å) permits loss of Met80-heme ligation creating an available coordination site to catalyze the peroxidase activity mediated by cytochrome c early in apoptosis. However, Ala81 and Gly83 move significantly (RMSDs of 2.18 and 1.26 Å, respectively). Ala81 and Gly83 evolve to Ile and Val, respectively, in human cytochrome c and peroxidase activity decreases 25-fold relative to the yeast protein at pH 7. To test the hypothesis that these residues evolved to restrict the peroxidase activity of cytochrome c, A81I and G83V variants of yeast iso-1-cytochrome c were prepared. For both variants, the apparent pKa of the alkaline transition increases by 0.2 to 0.3 relative to the wild type (WT) protein and the rate of opening the heme crevice is slowed. The cooperativity of acid unfolding is decreased for the G83V variant. At pH 7 and 8, the catalytic rate constant, kcat, for the peroxidase activity of both variants decreases relative to WT, consistent with the effects on alkaline isomerization. Below pH 7, the loss in the cooperativity of acid unfolding causes kcat for peroxidase activity to increase for the G83V variant relative to WT. Neither variant decreases kcat to the level of the human protein, indicating that other residues also contribute to the low peroxidase activity of human cytochrome c.

Dual‐Hemin‐Labelled Catalytic Molecular Beacon: A Monomer‐Dimer Switching Probe for Sensitive Chemiluminescence Detection of Biomolecules

AbstractThe stem‐loop structure of molecular beacon (MB) makes it a powerful nucleic acid probe for homogenous and highly specific bioanalysis. Tradition MBs have an intrinsic limitation on sensitivity because one target molecule converts only one beacon molecule to its fluorescent conformation. Herein, taking full advantages of the self‐dimerization behavior and catalytic characteristic of hemin, we engineered a new class of catalytic MB. Both ends of MB are labeled with hemin, and then target‐induced opening of stem‐loop structure switches hemin dimer to monomer. Hemin dimer exhibits a low peroxidase activity, whereas hemin monomer with high catalytic activity can produce strong chemiluminescence (CL) emission in the presence of luminol and H2O2. Thus, this catalytic MB can highly specifically report target in homogeneous solution by hemin‐driven CL signal. One target can introduce two catalytic cycles, exhibiting a higher sensitivity than traditional MB. The formation of hemin dimer further strengthens the stability of stem‐loop structure, which greatly reduces the background and improves the specificity. More importantly, the assay can also be adapted for colorimetric and fluorescent readout by changing the catalytic substrate. Therefore, this catalytic MB is a novel and promising probe for developing sensitive and diverse biosensing platform.

Ascorbate in the apoplast of elongating plant cells

It was shown that basipetal retardation of cell elongation in the growth zone of etiolated maize mesocotyls correlates with a steep decrease in the apoplastic ascorbic acid (ASC) concentration (50 μM → 10 μM) and ascorbate redox state (17 % → 5 %). Exogenous ASC (0.3 mM) not only inhibits peroxidase-dependent oxidation of phenols in vitro. It also exerts a highly specific effect on the secretion of peroxidases by stimulating the release of some isoforms while inhibiting the release of others to the cell walls. This effect points to the hypothetic signaling function of apoplastic ascorbate. Previously, we described a basipetal decrease in hydrogen peroxide concentration in the apoplast (from 5.1 to 2.0 μM) and a two-times increase in cell wall peroxidase potential activity (Sharova et al., 2012). Summarizing found gradients, we can assume that the conditions in the apoplast of the upper mesocotyl segment are favorable for the occurrence of the Fenton reaction (high ASC and hydrogen peroxide concentrations) and unfavorable for the oxidation of phenols (high ASC concentration and low potential peroxidase activity), which contributes to cell wall extensibility and rapid cell elongation.

Exogenous ascorbic acid mitigates flood stress damages of Vigna angularis

Prolonged water stress adversely affects many aspects of plant physiology, resulting in severe damage to growth and productivity. In response to this and other environmental stresses, plants have evolved complex physiological and biochemical adaptations. To boost existing plant defense mechanisms, this study quantified the negative effects of waterlogging stress and how it may be mitigated by the addition of a natural protective agent. Adzuki beans (Vigna angularis) were grown in commercially available microbe-free soil and subjected to waterlogging stress for 2 weeks. Waterlogging significantly reduced all growth-related variables: shoot length, fresh and dry biomass, chlorophyll content in stressed versus unstressed plants. Waterlogging stress generated reactive oxygen species that heavily damaged plant tissues, causing electrolyte leakage and eliciting an antioxidative response. Specifically, stress-response phytohormone content altered, with a reduction in abscisic acid (ABA) and an increase in jasmonic acid (JA). Furthermore, antioxidants such as malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), polyphenol oxidase (PPO), and peroxidase (POD) were significantly enhanced in waterlogged plants versus non-waterlogged plants. Supplementation of exogenous ascorbic acid (ASC) at 3, 5, and 7 mM revealed that the lowest concentration further reduced ABA and increased JA, enhancing water evaporation rates to raise water-stress tolerance. Moreover, 3 mM ASC also led to lower MDA, CAT, SOD, PPO, POD, and ascorbate peroxidase concentrations in waterlogged plants than in waterlogged plant not treated with ASC. Thus, ASC at a concentration of 3 mM was the most successful in relieving effects of waterlogging stress on plants.

LIPID COMPOSITION AND FUNCTIONAL STATE OF MEMBRANE SYSTEMS IN STELLARIA HUMIFUSA

The object of the study is Stellaria humifusa ( Caryophyllaceae ) – a polycarpic herb with a long taproot; an almost Arctic hygrophyte with circumpolar distribution. Plants form mats and grow on rock outcrops near coastal areas. The plant community consists of only one species, and is covered with a layer of dead leaves from the previous year. The study of lipids showed that during active growth S. humifusa has lipid fractions in the functionally active state. The fraction of neutral lipids (a structural component of the cell and its emergency stores) dominates in terms of the percentage of saturated fatty acids (FA). The fraction of phospholipids (the main membrane system of the cell) has the greatest content of FA with high quantities of diene, triene and saturated FA. This fraction contains the maximum amount of linoleic acid. The fraction of glycolipids (lipids of chloroplast membranes) accounts for around 32 % of the plant’s total FA. It indicates a tense lipid metabolism associated with photosynthetic activity. This fraction contains less of diene and saturated FA, but significantly more of triene FA, including linolenic acid, comparing to the other groups The study of AOS activity in S. humifusa leaves revealed relatively low peroxidase activity (2.2 and 1 μmol TG/mg protein at pH 5 and 7.8, respectively) simultaneously with high catalase activity (366 μmol H 2 O 2 /mg protein) as compared to other herbaceous plants. This fact possibly indicates the species is adapted to the environment. The high level of unsaturation of the lipid structure of the photosynthetic apparatus membrane system contributes a lot to the maintenance of its high functional activity in S. humifusa .

White muscle disease in foals: focus on selenium soil content. A case series

BackgroundWhite muscle disease (WMD) is a nutritional myopathy caused by selenium (Se) deficiency. In most soils, Se is present in low concentrations, sometimes even below 0.2 mg/kg, a trend which is seen in many countries. Apart from total soil Se concentrations, soil conditions may be such that the bio-availability of Se is so low that it causes very low uptake in plants which can ultimately lead to deficiency problems in animals. This is the first case series to report clinical WMD in foals in areas deficient in Se, in the Netherlands.The aim of the current report is to provide an overview of the clinical history, symptoms and (clinical) pathology of 8 newborn foals living at 4 different premises and suffering from WMD together with the effectiveness of Se and vitamin E (Vit E) supplementation in the affected foals, their dams and herd members. Hands on practical information is provided to apply a correct and effective Se supplementation management in horses and which pitfalls need to be avoided for a successful approach.Case presentationCase features and history were mapped out for all foals. Se and Vit E status were assessed for the foals, their dams and herd members, at admission and after 3 months of Vit E/Se supplementation.Common symptoms were muscle weakness, inability to rise, lethargy and inadequate suckle reflex together with increased serum muscle enzymes and low glutathione peroxidase (GSH-Px) and low to normal serum vit E levels. Necropsy revealed necrosis of skeletal muscles consistent with nutritional myopathy. Se status of the dams and herd members correlated well with the Se status of the foals. All surviving foals (n = 6) showed normal Vit E and GSH-Px levels after supplementation, likewise, all horses tested at premises 1, 3 and 4. However, dams and herd members in premises 2 showed no normalization. Horses of that premises were diagnosed with pyrrolizidine intoxication one year prior to the study.ConclusionsCertain regions in the Netherlands are sufficiently Se deficient to predispose newborn foals to develop WMD, especially when they are being fed a diet that mainly consists of locally harvested roughage.

TeA is a key virulence factor for Alternaria alternata (Fr.) Keissler infection of its host

A toxin-deficient mutant strain, HP001 mutant of Alternaria alternata, whose mycelium is unable to infect its host, produces little tenuazonic acid (TeA) toxin. How TeA plays a role in initiating host infection by A. alternata remains unclear. In this research we use Imaging-PAM based on chlorophyll fluorescence parameters and transmission electron microscopy to explore the role of TeA toxin during the infection process of A. alternata. Photosystem II damage began even before wild type mycelium infected the leaves of its host, croftonweed (Ageratina adenophora). Compared with the wild type, HP001 mutant produces morphologically different colonies, hyphae with thinner cell walls, has higher reactive oxygen species (ROS) content and lower peroxidase activity, and fails to form appressoria on the host surface. Adding TeA toxin allows the mutant to partially recover these characters and more closely resemble the wild type. Additionally, we found that the mutant is able to elicit disease symptoms when its mycelium is placed on leaves whose epidermis has been manually removed, which indicates that TeA may be determinant in the fungus recognition of its plant host. Lack of TeA toxin appears responsible for the loss of pathogenicity of the HP001 mutant. As a key virulence factor, TeA toxin not only damages the host plant but also is involved in maintaining ROS content, host recognition, inducing appressoria to infect the host and for allowing completion of the infection process.

SU19. Effects of N-Acetyl-Cysteine as an Add-on to Standard Treatment on Neurocognition in Early Psychosis

Abstract Background: Schizophrenia is associated with neurocognitive dysfunction already in the early phase of the disease.1 However, cognitive impairments are actually poorly treated by pharmacological interventions, leaving severe problems in functioning.2 Increasing evidence suggest oxidative stress and redox dysregulation play a role in the emergence of psychosis.3 In particular, levels of glutathione (GSH) are lower in chronic schizophrenia.4 In addition, a previous trial with the antioxidant N-acetyl-cysteine (NAC) led to negative symptoms reduction in chronic patients.5 Therefore, we explored if NAC had also an impact on neurocognition in early psychosis (EP) patients. Methods: The study was a 6-month, double-blind, randomized, placebo-controlled trial of NAC supplementation (2700 mg/d) to standard medications. Neurocognition was assessed at baseline and at the end of treatment with the MATRICS Consensus Cognitive Battery (MCCB),6 excluding the Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT). Sixty-one patients (31 NAC, 30 placebo) with a diagnostic of psychotic disorder and less than 12 months of antipsychotic treatment were enrolled. Results: We found significant interaction Time × Treatment in favor of NAC on the MCCB processing speed factor and for 2 of 3 processing speed’s tasks (Trail Making A and Verbal Fluency). The improvement in processing speed within the NAC group was correlated with a decrease in negative symptoms. In addition, it was possible to identify a subgroup of patients who responded to NAC treatment considering their biological variables. Indeed, patients having a low peroxidase (GPx) activity at baseline benefited more than others from NAC supplementation in terms of processing speed’s scores. Moreover, in those individuals only, the improvement in processing speed was related to a decrease of the GSH reductase (GR) activity and to a regulation of the balance GPx – GR. Conclusion: Addition of NAC improved processing speed in EP patients, in particular in those who displayed a low basal level of redox dysregulation. Further, larger studies on antioxidant interventions are needed to replicate these findings. This work was supported by the National Center of Competence in Research (NCCR) “SYNAPSY – The Synaptic Bases of Mental Diseases” financed by the Swiss National Science Foundation, Damm-Etienne Foundation, Alamaya Foundation, the Commonwealth of Massachusetts Center of Excellence in Clinical Neuroscience and Psychopharmacological Research (SCDMH82101008006, LJS), and the Weisman family (LJS).

High Performance Reduction of H2O2 with an Electron Transport Decaheme Cytochrome on a Porous ITO Electrode.

The decaheme cytochrome MtrC from Shewanella oneidensis MR-1 immobilized on an ITO electrode displays unprecedented H2O2 reduction activity. Although MtrC showed lower peroxidase activity in solution compared to horseradish peroxidase, the ten heme cofactors enable excellent electronic communication and a superior activity on the electrode surface. A hierarchical ITO electrode enabled optimal immobilization of MtrC and a high current density of 1 mA cm–2 at 0.4 V vs SHE could be obtained at pH 6.5 (Eonset = 0.72 V). UV–visible and Resonance Raman spectroelectrochemical studies suggest the formation of a high valent iron-oxo species as the catalytic intermediate. Our findings demonstrate the potential of multiheme cytochromes to catalyze technologically relevant reactions and establish MtrC as a new benchmark in biotechnological H2O2 reduction with scope for applications in fuel cells and biosensors.

Host plant growth promotion and cadmium detoxification in Solanum nigrum, mediated by endophytic fungi

Current investigation conducted to evaluate the associated fungal endophyte interactions of a Cd hyper-accumulator Solanum nigrum Korean ecotype under varying concentrations of Cd. Two indole-3-acetic acid (IAA) producing fungal strains, RSF-4L and RSF-6L, isolated from the leaves of S. nigrum, were initially screened for Cd tolerance and accumulation potential. In terms of dry biomass production, the strain RSF-6L showed higher tolerance and accumulation capacity for Cd toxicity in comparison to RSF-4L. Therefore, RSF-6L was applied in vivo to S. nigrum and grown for six weeks under Cd concentrations of 0, 10, and 30mgKg−1 of dry sand. The effect of fungal inoculation assessed by plant physiological responses, endogenous biochemical regulations, and Cd profile in different tissues. Significant increase were observed in plant growth attributes such as shoot length, root length, dry biomass, leaf area, and chlorophyll contents in inoculated RSF-6L plants in comparison to non-inoculated plants with or without Cd contamination. RSF-6L inoculation decreased uptake of Cd in roots and above ground parts, as evidenced by a low bio-concentration factor (BCF) and improved tolerance index (TI). However, Cd concentration in the leaves remained the same for inoculated and non-inoculated plants under Cd spiking. Fungal inoculation protected the host plants, as evidenced by low peroxidase (POD) and polyphenol peroxidase (PPO) activities and high catalase (CAT) activity. Application of appropriate fungal inoculation that can improve tolerance mechanisms of hyper-accumulators and reduce Cd uptake can be recommended for phyto-stabilisation/immobilisation of heavy metals in crop fields.

ACTIVITY OF LEUKOCYTE ENZYMES IN AMERICAN MINK (NEOVISON VISON): GENOTYPIC AND AGE-RELATED DIFFERENCES

The activity and localization of enzymes in blood leukocytes were examined in dark brown (+/+), silver-blue (p/p) and sapphire (a/a p/p) minks during several periods of postnatal development. This study was performed by morphometric and cytochemical methods using light microscopy and image analysis software “VidеoTest». Significant genotypic differences were determined in the distribution of peroxidase, naphthol AS-D chloroacetate esterase (NASDCE) and alkaline phosphatase (AP) in leukocytes. Sapphire mink (a/a) are characterized by the lowest reproductive potential and increased postnatal mortality among the studied genotypes. Leukocytes of sapphire mink showed a significant increase in the size of and a change in the number of peroxidase- and esterase-positive structures, as well as the presence of phosphatase-negative areas in the cytoplasm. Apparently, these structures are abnormal granules and indicate the disturbance of granulogenesis. Mink of all the three genotypes demonstrated similar age-related changes of peroxidase and alkaline phosphatase activities. The lowest peroxidase activity was observed in early postnatal development, whereas the highest – at the age of 120 days. The increase in alkaline phosphatase activity occurred during the phase of active growth – on the 60th day of postnatal ontogeny. The pattern of age-related changes in NASDCE activity depended on the mink’s genotype. Sapphire mink had the highest level of NASDCE activity at the age of 4 days and the lowest – at 180 days, whereas both dark brown and silver-blue mink at the same age (180 days) had the highest values of NASDCE activity. The postnatal dynamics of the enzymes’ activity in the three genotypes apparently reflects the specific features of metabolism in leukocytes in different periods. The cytochemical features of peripheral blood leukocytes in sapphire mink suggest the presence of a morphofunctional cellular defect, which is the cause of the animals’ low viability.

The thioredoxin MoTrx2 protein mediates reactive oxygen species (ROS) balance and controls pathogenicity as a target of the transcription factor MoAP1 in Magnaporthe oryzae.

We have shown previously that the transcription factor MoAP1 governs the oxidative response and is important for pathogenicity in the rice blast fungus Magnaporthe oryzae. To explore the underlying mechanism, we have identified thioredoxin MoTrx2 as a target of MoAP1 in M. oryzae. Thioredoxins are highly conserved 12-kDa oxidoreductase enzymes containing a dithiol-disulfide active site, and function as antioxidants against free radicals, such as reactive oxygen species (ROS). In yeast and fungi, thioredoxins are important for oxidative stress tolerance and growth. To study the functions of MoTrx2, we generated ΔMotrx2 mutants that exhibit various defects, including sulfite assimilation, asexual and sexual differentiation, infectious hyphal growth and pathogenicity. We found that ΔMotrx2 mutants possess a defect in the scavenging of ROS during host cell invasion and in the active suppression of the rice defence response. We also found that ΔMotrx2 mutants display higher intracellular ROS levels during conidial germination, but lower peroxidase and laccase activities, which contribute to the attenuation in virulence. Given that the function of MoTrx2 overlaps that of MoAP1 in the stress response and pathogenicity, our findings further indicate that MoTrx2 is a key thioredoxin protein whose function is subjected to transcriptional regulation by MoAP1 in M. oryzae.