Non-enzymatic Systems Research Articles

Nitric Oxide as a Savior Molecule Against Stress Induced by Chromium and Cadmium

Heavy metals (HMs) pollution is one of soil problems imposing great agronomic challenges leading to obstacles in ascertaining food safety. The deposition of HMs beyond permissible limits due to their uses in various agricultural, industrial and household purposes, greatly affect the soil fertility and physio-biochemical activities of plants growing in such soils. Among HMs, cadmium (Cd) and chromium (Cr) are very toxic, non-essential heavy metals whose concentrations have built-up recently in our environment due to several manmade activities. These elements enter into living organisms either by absorption through plants or are directly consumed by animals or microbes. They induce various morphological and physio-biochemical changes in plants ranging from seed germination, growth, nutrient uptake, photosynthesis to hormonal interactions. Excess reactive oxygen species (ROS) and reactive nitrogen species (RNS) generation are two important markers of nitro-oxidative stress during heavy metal stress. Plants counteract by activating defence responses by inducing expression of antioxidant enzymes like (CAT, SOD, APX) and antioxidant compounds like Vitamin C and GSH. Nitric oxide (NO) is one of the active gaseous molecules generated during nitro-oxidative stress induced by HMs like Cd and Cr. NO is generated in the plants by diverse enzymatic and non-enzymatic systems. The specific and dedicated enzyme system for NO generation is not yet identified in the plants. NO helps to counteract the effects of HMs by activating various biochemical machineries such as induction of antioxidant defence systems, protein nitrosylation, programmed cell death. It is the molecule that has very promising roles and need to be explored much in relation to heavy metals.

Influence of “Metisevit” feed additive and liposomal preparation “Lipointersil” on the level of vitamins in the blood of bulls at experimental chronic cadmium toxicosis

The article presents the results of research on the effect of feed additive “Metisevit” and liposomal drug “Lipointersil” on the level of vitamins in the blood of bulls in experimental chronic cadmium toxicosis. The research was conducted on the basis of a farm in the village of Ivanivtsi, Zhydachiv district, Lviv region, on 15 bulls of six months of age, Ukrainian black-spotted dairy breed, which were formed into 3 groups of 5 animals each: control and two experimental groups. The bulls of the control group were fed cadmium chloride at a dose of 0.04 mg/kg body weight for 30 days. The bulls of the first experimental group were fed cadmium chloride at a dose of 0.04 mg/kg body weight for 30 days and fed a dietary supplement “Metisevit” at a dose of 0.36 g/kg of feed. The bulls of the second experimental group were fed cadmium chloride at a dose of 0.04 mg/kg body weight for 30 days and fed a dietary supplement “Metisevit” in the above dose. On the first and seventh days of the experiment, bulls of this experimental group were injected intramuscularly with liposomal drug “Lipointersil” at a dose of 5 ml per animal. The composition of the liposomal drug “Lipointersil” includes interferon and milk thistle. In the study of the non-enzymatic part of the antioxidant system of the body of bulls under cadmium load found a decrease in vitamins A and E. The use of feed additive “Metisevit” increased the content of vitamin E in the blood of bulls of the second experimental group by 10.5 % experiment – by 37.9 % relative to the control group. With the additional use of liposomal drug “Lipointersil” in the blood of bulls found a more likely increase in vitamin E levels throughout the experiment than in the second experimental group, where respectively on the 15th and 20th day of the experiment, this figure increased by 35.3 and 55.1 %. The increase in the content of vitamin E in the blood of experimental animals is due to the feeding of the feed supplement “Metisevit”, which contains this vitamin. A similar increase is observed in the study of vitamin A in the blood of bulls of experimental groups. It was found that when using a feed additive and liposomal preparation for bulls, on the 15th day of the experiment the level of vitamin A in the blood of the first experimental group increased by 19.4 %, and in the blood of the second experimental group – by 26.9 % relative to the control group. Thus, the use of feed supplement “Metisevit” and liposomal drug “Lipointersil” for bulls, which are under conditions of cadmium load, helped to increase the non-enzymatic system of antioxidant protection, namely vitamins A and E.

Autocatalysis in Formose Reaction and Formation of RNA Nucleosides.

Understanding of the abiotic formation of nucleosides under geochemical conditions is currently a major scientific challenge. In this study, free radical pathways for formation of RNA nucleosides with canonical nucleobases are proposed for the first time. The pathways proceed with relatively low energy barriers for the formation of ribose as well as all RNA nucleosides. The formose reaction proceeds either with or without Ca2+ and CaOH+ cations. An autocalytic cycle for the formation of both glycolaldehyde and glyceraldehyde is identified when Ca2+ or CaOH+ cations are involved in the reaction. The results suggest that Ca2+ cations are not involved in the formation of ribose from glyceraldehyde. In addition, these pathways lead to the formation of dihydroxyacetone and d-erythrose. Calculated results show that the glycosidic bond can be formed abiotically between the d-ribose and the nucleobase, where d-ribose forms a cyclic free radical that subsequently reacts with the neutral nucleobase. Involvement of proper nucleobase tautomer is important for the formation of RNA nucleosides. Our approaches provide a solution for the long-standing question of how the glycosidic bond is formed under the abiotic conditions with low energy barriers. The pathways for formation of the sugars without a catalyst are relevant to the formation of sugars in interstellar clouds. On the other hand, the autocalysis in the formose reaction followed by the formation of the nucleosides is appropriate for the abiotic synthesis taking place in the presence of water in the early Earth environment. The Ca2+ and CaOH+ cations appear to be the first nonenzymatic catalytic systems for formation of biomolecules.

Nanoparticles of chosen noble metals as reactive oxygen species scavengers

Reactive oxygen species (ROS) play an important role in various physiological processes of living organisms. However, their increased concentration is usually considered as a threat for our health. Plants, invertebrates, and vertebrates including humans have various enzymatic and non-enzymatic defence systems against ROS. Unfortunately, both bad condition of surrounding environment and unhealthy lifestyle can interfere with an activity of enzymes responsible for a regulation of ROS levels. Therefore, it is important to look for alternative ROS scavengers, which could be administrated to chosen tissues to prevent pathological processes such as distortion of DNA or RNA structures and oxidation of proteins and lipids. One of the most recently proposed solutions is the application of nanozymes, which could mimic the activity of essential enzymes and prevent excessive activity of ROS. In this work, nanoparticles of Au, Pt, Pd, Ru and Rh were synthesized and studied in this regard. Peroxidase-, catalase (CAT)- and superoxide dismutase (SOD)-like activity of obtained nanoparticles were tested and compared using different methods. The influence of bovine and human albumins on CAT- and peroxidase-like activity was examined. Moreover, in the case of CAT-like activity, an influence of pH and temperature was examined and compared. Determination of SOD-like activity using the methods described for the examination of the activity of native enzyme was not fully successful. Moreover, cytotoxicity of chosen nanoparticles was studied on both regular and tumor cells.

Drought-hardening improves drought tolerance in Nicotiana tabacum at physiological, biochemical, and molecular levels

BackgroundDrought stress is the most harmful one among other abiotic stresses with negative impacts on crop growth and development. Drought-hardening is a feasible and widely used method in tobacco seedlings cultivation. It has gained extensive interests due to its role in improving drought tolerance. This research aimed to investigate the role of drought-hardening and to unravel the multiple mechanisms underlying tobacco drought tolerance and adaptation.ResultsThis study was designed in which various drought-hardening treatments (CK (no drought-hardening), T1 (drought-hardening for 24 h), T2 (drought-hardening for 48 h), and T3 (drought-hardening for 72 h)) were applied to two tobacco varieties namely HongHuaDaJinYuan (H) and Yun Yan-100 (Y). The findings presented a complete framework of drought-hardening effect at physiological, biochemical, and gene expression levels of the two tobacco varieties under drought stress. The results showed that T2 and T3 significantly reduced the growth of the two varieties under drought stress. Similarly, among the various drought-hardening treatments, T3 improved both the enzymatic (POD, CAT, APX) and non-enzymatic (AsA) defense systems along with the elevated levels of proline and soluble sugar to mitigate the negative effects of oxidative damage and bringing osmoregulation in tobacco plants. Finally, the various drought-hardening treatments (T1, T2, and T3) showed differential regulation of genes expressed in the two varieties, while, particularly T3 drought-hardening treatment-induced drought tolerance via the expression of various stress-responsive genes by triggering the biosynthesis pathways of proline (P5CS1), polyamines (ADC2), ABA-dependent (SnRK2, AREB1), and independent pathways (DREB2B), and antioxidant defense-related genes (CAT, APX1, GR2) in response to drought stress.ConclusionsDrought-hardening made significant contributions to drought tolerance and adaptation in two tobacco variety seedlings by reducing its growth and, on the other hand, by activating various defense mechanisms at biochemical and molecular levels. The findings of the study pointed out that drought-hardening is a fruitful strategy for conferring drought tolerance and adaptations in tobacco. It will be served as a useful method in the future to understand the drought tolerance and adaptation mechanisms of other plant species.Graphical abstractDrought-hardening improved drought tolerance and adaptation of the two tobacco varieties. T1 indicates drought-hardening for 24 h, T2 indicates drought-hardening for 48 h, T3 indicates drought-hardening for 72 h

Antioxidant Profile of Pepper (Capsicum annuum L.) Fruits Containing Diverse Levels of Capsaicinoids.

Capsicum is the genus where a number of species and varieties have pungent features due to the exclusive content of capsaicinoids such as capsaicin and dihydrocapsaicin. In this work, the main enzymatic and non-enzymatic systems in pepper fruits from four varieties with different pungent capacity have been investigated at two ripening stages. Thus, a sweet pepper variety (Melchor) from California-type fruits and three autochthonous Spanish varieties which have different pungency levels were used, including Piquillo, Padrón and Alegría riojana. The capsaicinoids contents were determined in the pericarp and placenta from fruits, showing that these phenyl-propanoids were mainly localized in placenta. The activity profiles of catalase, total and isoenzymatic superoxide dismutase (SOD), the enzymes of the ascorbate–glutathione cycle (AGC) and four NADP-dehydrogenases indicate that some interaction with capsaicinoid metabolism seems to occur. Among the results obtained on enzymatic antioxidants, the role of Fe-SOD and the glutathione reductase from the AGC is highlighted. Additionally, it was found that ascorbate and glutathione contents were higher in those pepper fruits which displayed the greater contents of capsaicinoids. Taken together, all these data indicate that antioxidants may contribute to preserve capsaicinoids metabolism to maintain their functionality in a framework where NADPH is perhaps playing an essential role.

Enhanced mismatch selectivity of T4 DNA ligase far above the probe: Target duplex dissociation temperature

T4 DNA ligase is a widely used ligase in many applications; yet in single nucleotide polymorphism analysis, it has been found generally lacking owing to its tendency to ligate mismatches quite efficiently. To address this lack of selectivity, we explored the effect of temperature on the selectivity of the ligase in discriminating single base pair mismatches at the 3'-terminus of the ligating strand using short ligation probes (9-mers). Remarkably, we observe outstanding selectivities when the assay temperature is increased to 7 °C to 13 °C above the dissociation temperature of the matched probe:target duplexes using commercially available enzyme at low concentration. Higher enzyme concentration shifts the temperature range to 13 °C to 19 °C above the probe:target dissociation temperatures. Finally, substituting the 5'-phosphate terminus with an abasic nucleotide decreases the optimal temperature range to 7 °C to 10 °C above the matched probe:target duplex. We compare the temperature dependence of the T4 DNA ligase catalyzed ligation and a nonenzymatic ligation system to contrast the origin of their modes of selectivity. For the latter, temperatures above the probe:target duplex dissociation lead to lower ligation conversions even for the perfect matched system. This difference between the two ligation systems reveals the uniqueness of the T4 DNA ligase's ability to maintain excellent ligation yields for the matched system at elevated temperatures. Although our observations are consistent with previous mechanistic work on T4 DNA ligase, by mapping out the temperature dependence for different ligase concentrations and probe modifications, we identify simple strategies for introducing greater selectivity into SNP discrimination based on ligation yields.

Protein-responsive protein release of supramolecular/polymer hydrogel composite integrating enzyme activation systems

Non-enzymatic proteins including antibodies function as biomarkers and are used as biopharmaceuticals in several diseases. Protein-responsive soft materials capable of the controlled release of drugs and proteins have potential for use in next-generation diagnosis and therapies. Here, we describe a supramolecular/agarose hydrogel composite that can release a protein in response to a non-enzymatic protein. A non-enzymatic protein-responsive system is developed by hybridization of an enzyme-sensitive supramolecular hydrogel with a protein-triggered enzyme activation set. In situ imaging shows that the supramolecular/agarose hydrogel composite consists of orthogonal domains of supramolecular fibers and agarose, which play distinct roles in protein entrapment and mechanical stiffness, respectively. Integrating the enzyme activation set with the composite allows for controlled release of the embedded RNase in response to an antibody. Such composite hydrogels would be promising as a matrix embedded in a body, which can autonomously release biopharmaceuticals by sensing biomarker proteins.

Cytokinin alleviates cypermethrin toxicity in Nostoc muscorum by involving nitric oxide: Regulation of exopolysaccharides secretion, PS II photochemistry and reactive oxygen species homeostasis

Growth of the most important nitrogen fixing cyanobacterium Nostoc muscorum is reported to be badly affected by the application of insecticides. To overcome their damaging effects, several strategies are being used. Out of these, some works on kinetin (KN, a synthetic cytokinin) has been recognized that it can overcome toxicity of insecticides in cyanobacteria. Besides this, it is now known that every hormone needs certain second messengers such as nitric oxide (NO) for its action. But implication of NO in KN-mediated regulation of insecticide toxicity is yet to be investigated. Hence in the current study, we have investigated the possible involvement of NO in KN-mediated regulation of cypermethrin toxicity in the cyanobacterium Nostoc muscorum. Cypermethrin decreased growth of Nostoc muscorum which was accompanied by decreased pigment contents and altered photosystem II (PS II) photochemistry that resulted in inhibition of photosynthetic process but KN significantly ameliorated cypermethrin toxicity. Cypermethrin induced production of free radicals (in-vivo and in-vitro) and weakened defensive mechanism (enzymatic and non-enzymatic defense system) which was restored by KN. Further, the results revealed that NG-nitro-l-arginine methyl ester (l-NAME, an inhibitor of nitric oxide synthase) worsened the effect of cypermethrin toxicity even in the presence of KN while 2-4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO, a scavenger of NO) reversed KN-mediated amelioration even in the presence of sodium nitroprusside (SNP, an NO donor), suggesting that endogenous NO is required for mitigation of cypermethrin toxicity. Overall, our results first time show that endogenous NO is essential for KN-mediated mitigation of cypermethrin toxicity in the Nostoc muscorum.

Redox-Modulating Agents in the Treatment of Viral Infections.

Viruses use cell machinery to replicate their genome and produce viral proteins. For this reason, several intracellular factors, including the redox state, might directly or indirectly affect the progression and outcome of viral infection. In physiological conditions, the redox balance between oxidant and antioxidant species is maintained by enzymatic and non-enzymatic systems, and it finely regulates several cell functions. Different viruses break this equilibrium and induce an oxidative stress that in turn facilitates specific steps of the virus lifecycle and activates an inflammatory response. In this context, many studies highlighted the importance of redox-sensitive pathways as novel cell-based targets for therapies aimed at blocking both viral replication and virus-induced inflammation. In the review, we discuss the most recent findings in this field. In particular, we describe the effects of natural or synthetic redox-modulating molecules in inhibiting DNA or RNA virus replication as well as inflammatory pathways. The importance of the antioxidant transcription factor Nrf2 is also discussed. Most of the data reported here are on influenza virus infection. We believe that this approach could be usefully applied to fight other acute respiratory viral infections characterized by a strong inflammatory response, like COVID-19.

Peripheral non-enzymatic antioxidants in patients with schizophrenia: a case-control study

BackgroundRecent studies show that oxidative stress is associated with the pathogenesis of schizophrenia. There are two major types of antioxidant systems in vivo, namely enzymatic antioxidants and non-enzymatic antioxidants. This study investigated differences of non-enzymatic antioxidants between schizophrenia patients and healthy controls.MethodsPeripheral UA, ALB, and TBIL of 107 schizophrenic patients in the acute stage and 101 in the remission stage were measured respectively, so were 273 healthy controls.ResultsThe levels of UA (P = 0.020) and TBIL (P < 0.001) of schizophrenic patients in the acute stage were higher than those of healthy controls, while the level of ALB (P < 0.001) was lower. Similar results were detected form schizophrenic patients in the remission stage. Schizophrenic patients in the acute stage were divided into antipsychotics-use subgroup (n = 56) and antipsychotics-naïve/free subgroup (n = 51). The level of UA (P = 0.001) in the antipsychotics-use subgroup was higher than that in the antipsychotics-naïve/free subgroup, while the level of TBIL (P = 0.002) was lower than that in the antipsychotics-naïve/free subgroup. Seventy-seven schizophrenic patients in the acute stage were followed up, and there was no significant difference in the level of UA before and after treatment, but levels of ALB (P < 0.001) and TBIL (P < 0.001) decreased significantly after the treatment.ConclusionThis study demonstrated that the dysfunction of the peripheral non-enzymatic anti-oxidation system might be involved in the pathogenesis of schizophrenia.

Improvement of ionizing gamma irradiation tolerance of Chlorella vulgaris by pretreatment with polyethylene glycol

Purpose: To evaluate the effects of polyethylene glycol (PEG) 6000 pretreatment on growth and physiological responses of eukaryotic microalga Chlorella vulgaris exposed to ionizing irradiation.Materials and methods: The microalgal cells pretreated with different PEG concentrations (0, 5, 10 and 20%) and then exposed to 300 Gray gamma irradiation at a dose rate of 0.5 Gy s−1. The various growth and physiological parameters including algal growth, cell size, the degree of electrolyte leakage (EL) and lipid peroxidation, the content of pigments and proline and the activity of antioxidant enzymes under gamma-free or 300 Gray gamma irradiation conditions were examined.Results: The results showed that PEG stimulated a higher growth and cell size under both stress-free and gamma-stress conditions. The maximum growth and cell size was reported when the algae was pretreated with 10% PEG. A relative increase of catalase activity was observed in all samples after exposing to gamma irradiation. However, the highest value was recorded for the gamma-radiated algae pretreated with 10% PEG. In the absence of PEG, gamma irradiation induced a significant reduction in ascorbate peroxidase activity, but with PEG pretreatment, the enzyme activity remained constant or even increased after gamma irradiation. On the other hand, although gamma irradiation stress generally suppressed the activity of superoxide dismutase in all cells, pretreating the algae with PEG could diminish this suppressing effect at all applied concentrations. Compared to the PEG-free controls, a lower rate of chlorophylls and membrane integrity loss was shown in the PEG-treated algae when exposed to gamma stress. Total carotenoid content in PEG-treated algae was also similar under both gamma-free and gamma-radiated conditions. A PEG-independent increase in proline accumulation was reported under gamma-irradiation treatment.Conclusions: Overall, the results suggested that PEG pretreatment could improve gamma-irradiation tolerance in C. vulgaris probably by stimulating a range of enzymatic and non-enzymatic reactive oxygen species scavenging systems. The microalgae may also consume PEG to break down and use it as an alternative source of carbon during stress which should be further studied in detail.

Oxidant/Antioxidant Profile in the Thoracic Aneurysm of Patients with the Loeys-Dietz Syndrome.

Patients with the Loeys-Dietz syndrome (LDS) have mutations in the TGF-βR1, TGF-βR2, and SMAD3 genes. However, little is known about the redox homeostasis in the thoracic aortic aneurysms (TAA) they develop. Here, we evaluate the oxidant/antioxidant profile in the TAA tissue from LDS patients and compare it with that in nondamaged aortic tissue from control (C) subjects. We evaluate the enzymatic activities of glutathione peroxidase (GPx), glutathione S-transferase (GST), glutathione reductase (GR), catalase (CAT), superoxide dismutase (SOD) isoforms, and thioredoxin reductase (TrxR). We also analyze some antioxidants from a nonenzymatic system such as selenium (Se), glutathione (GSH), and total antioxidant capacity (TAC). Oxidative stress markers such as lipid peroxidation and carbonylation, as well as xanthine oxidase (ORX) and nuclear factor erythroid 2-related factor 2 (Nrf2) expressions, were also evaluated. TAA from LDS patients showed a decrease in GSH, Se, TAC, GPx, GST, CAT, and TrxR. The SOD activity and ORX expressions were increased, but the Nrf2 expression was decreased. The results suggest that the redox homeostasis is altered in the TAA from LDS patients, favoring ROS overproduction that contributes to the decrease in GSH and TAC and leads to LPO and carbonylation. The decrease in Se and Nrf2 alters the activity and/or expression of some antioxidant enzymes, thus favoring a positive feedback oxidative background that contributes to the TAA formation.

Effect of biochar and redmud amendment combinations on Salix triandra growth, metal(loid) accumulation and oxidative stress response.

Remediation of metal(loid) polluted soils is an important area of research nowadays. In particular, one remediation technique is much studied, phytomanagement. Phytomanagement combines amendment application and plant growth in order to reduce the risk posed by contaminants. Salicaceae plants showed tolerance towards metal(loid)s and the ability to accumulate high amounts of metal(loid)s in their tissue. Amendments are often applied to counterbalance the reduced soil fertility and high metal(loid) concentrations. Two amendments gathered attention over the last decades, biochar (product of biomass pyrolysis), which can be activated for better effects, and redmud (by-product of alumina production). Those two amendments showed ability to improve soil conditions and thus plant growth, although few studied their combined application. Moreover, since metal(loid)s are known to induce the overproduction of reactive oxygen species, it is important to measure the level of oxidative stress in the plant, to which plants respond using enzymatic and non-enzymatic systems. But no studies evaluate the response of Salicaceae plants to metal(loid) stress and amendment application at the biochemical level in a real soil condition. Therefore, a mesocosm study was set up to evaluate the effect of amending a mine soil with redmud combined to diverse biochars on the soil properties and Salix triandra growth, metal(loid) accumulation and stress marker levels. Results showed that all amendment combinations improved the soil fertility, reduced metal(loid) mobility and thus ameliorated Salix triandra growth, which accumulated metal(loid)s mainly in its roots. Moreover, among the different amendment combinations, Salix triandra plants still suffered from oxidative stress when grown on PG soil amended with redmud and chemical activated carbon, showing elevated levels of phenolic compounds and salicinoids and important antioxidant and enzymatic activities. Finally, one treatment showed levels of these stress markers similar or lower than the control, the combination of redmud with steam activated carbon. In conclusion, this treatment seemed a good solution in a phytomanagement strategy using Salix triandra, improving soil conditions and plant growth and reducing oxidative stress level in the plant roots.

Why Does the Halophyte Mesembryanthemum crystallinum Better Tolerate Ni Toxicity than Brassica juncea: Implication of Antioxidant Defense Systems.

The implication of enzymatic and non-enzymatic antioxidative systems in response to Ni was evaluated in the halophyte Mesembryanthemum crystallinum in comparison with the metal tolerant glycophyte species Brassica juncea. Seedlings of both species were hydroponically subjected during 21 days to 0, 25, 50, and 100 µM NiCl2. Growth parameters showed that the halophyte M. crystallinum was more tolerant to Ni than B. juncea. Malondialdehyde (MDA) content increased to a higher extent in B. juncea than in M. crystallinum. Antioxidant enzymesactivities were differently affected by Ni in both species. Nickel increased shoot superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities in B. juncea, whereas these activities were reduced in M. crystallinum when exposed to metal stress. The root SOD, APX and guaiacol peroxidase (GPX) activities increased upon Ni treatments for both species. The content of non-enzymatic antioxidative molecules such as glutathione, non-protein thiols and proline increased in Ni-treated plants, except for GSH content in the shoot of B. juncea. Based on the oxidative balance, our findings confirm the higher tolerance of the halophyte M. crystallinum to Ni-induced oxidative stress comparatively to B. juncea. We suggest that M. crystallinum is able to overcome the produced ROS using the non-enzymatic system, while Ni-induced oxidative stress was more acute in B. juncea, leading this species to mainly use the enzymatic system to protect against reactive oxygen species.

Crosstolerant Effect of Salt Priming and Viral Infection on Nicotiana Benthamiana

Currently, the salinization of soil one of the factors, which determine the productivity of crop plants. Under severe conditions, plants reveal the retardation in growth of shoots and roots,the decrease of productivity, because of biochemical and physiologicaleffects of salt high concentrations. To avoid any severe effect of biotic and abiotic stress is applied to the method of seed priming. Primed seed preserves the resistance signaling pathway for upcoming stress conditions. During biotic and biotic stress firstly accumulates reactive oxygen species which are the secondary messenger molecules in many signaling pathway of plant organisms. Excessive amounts of reactive oxygen species lead to macromolecules damage, such as lipids of cell walls, proteins, nucleic acids. To overcome the severe effect, plants evolved enzymatic and non-enzymatic systems of protection. The crucial enzymes are catalase, aldehyde oxidase, superoxide dismutase. The main components of the non-enzymatic antioxidant system are vitamins, low molecular mass substances such as glutathione. The phenomenon “cross-tolerance” suggests the resistance of plant organism to one stress by the exposure to another one. Early exposure salt stress to Nicotiana benthamiana leads to resistance to viral infection, change the activity of antioxidant enzymes (catalase, aldehyde oxidase). The analysis of viral particles revealed the decrease of viral particles content in salt primed plants.

Nitric oxide is involved in nano-titanium dioxide-induced activation of antioxidant defense system and accumulation of osmolytes under water-deficit stress in Vicia faba L.

Nano-titanium dioxide (nTiO2) has been reported to improve tolerance of plants against different environmental stresses by modulating various physiological and biochemical processes. Nitric oxide (NO) has been shown to act as an important stress signaling molecule during plant responses to abiotic stresses. The present work was planned to investigate the involvement of endogenous NO in nTiO2-induced activation of defense system of fava bean (Vicia faba L.) plants under water-deficit stress (WDS) conditions. Water-suffered plants showed increased concentration of hydrogen peroxide (H2O2) and superoxide (O2-) content coupled with increased electrolyte leakage and lipid peroxidation which adversely affected nitrate reductase (NR) activity, chlorophyll content and growth of the plants. However, application of 15mgL-1 nTiO2 to stressed plants significantly induced NR activity and synthesis of NO which elevated enzymatic and non-enzymatic defense system of the stressed plants and suppressed the generation of H2O2 and O2- content, leakage of electrolytes, and lipid peroxidation. Application of nTiO2, in association with NO, also enhanced the accumulation of osmolytes (proline and glycine betaine) that assisted the stressed plants in osmotic adjustment as witnessed by improved hydration level of the plants. Involvement of NO in nTiO2-induced activation of defense system was confirmed with NO scavenger cPTIO [2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide] which caused recurrence of WDS.

Operation of Queue and Stack by DNA Tiles

DNA is used as self-nanomaterials to assemble into specific structures. DNA tile provides a new idea for the application of DNA tile in the field of computing. Recent years, Queue and Stack are important linear data structures which are used in various software systems widely. The implementation of DNA based queue and stack has been studied continuously for many years. In the traditional DNA computing, queue and stack are mostly realized by DNA strands displacement, restriction endonuclease and ligase were used. However, as an active material, it has a high requirement for enzyme experimental conditions. The purpose of this paper is to implement queue and stack structures using non-enzyme systems. The rule of Queue is characterized by FIFO (first in first out), which allows for insertion at one end of the list and deletion at the other. The rule of Stack is characterized by FILO(first in last out), which allows for insertion and deletion at one end of the list. We are aimed to implement Queue and Stack using self-assembly and disassembly via DNA Tiles. No enzymes are needed for the whole experiment. As an enzyme-free system, it provides a new method to implement stack and queue.

Hyper-Resistance of the Bacillus licheniformis 24 Strain to Oxidative Stress Is Associated with Overexpression of Enzymatic Antioxidant System Genes

At the International Space Station (ISS), artificial living conditions are created and maintained to satisfy human needs, these conditions are also favorable for the growth of numerous microorganisms, molds and bacteria. Among the microorganisms detected on the ISS are those from the automicroflora of crew members, and a significant number of spore-forming bacteria. In most cases, this group of microorganisms gives rise to strains that are able to colonize, grow and reproduce on interior materials and equipment of stations, and may be involved in biodestructive processes. These bacteria show increased resistance to various stress factors, for example, DNA-damaging and oxidizing agents. The molecular mechanisms of this resistance to stress are poorly understood. As part of the sanitary-microbiological monitoring of the ISS habitat, the Bacillus licheniformis 24 strain was isolated. Here, we demonstrated that this strain has increased resistance to hydrogen peroxide and Paraquat when compared to the "terrestrial" B. licheniformis B-10956 strain. B. licheniformis 24 overexpressed genes encoding enzymes that neutralize reactive oxygen species, such as KatX catalase and the superoxide dismutases SodA and SodF. Apart from this, in comparison with B. licheniformis B-10956, of B. licheniformis 24 cells had lower hydrogen sulfide production that was associated with sharply reduced expression of the cysIJ operon that encodes sulfite reductase. The results indicate that enzymatic antioxidant protective systems make a more significant contribution to the hyper-resistance of Bacillus strains to oxidizing agents than components of non-enzymatic systems, such as hydrogen sulfide.

Enantioselective C-H Lactonization of Unactivated Methylenes Directed by Carboxylic Acids.

The formidable challenges of controlling site-selectivity, enantioselectivity, and product chemoselectivity make asymmetric C-H oxidation a generally unsolved problem for nonenzymatic systems. Discrimination between the two enantiotopic C-H bonds of an unactivated methylenic group is particularly demanding and so far unprecedented, given the similarity between their environments and the facile overoxidation of the initially formed hydroxylation product. Here we show that a Mn-catalyzed C-H oxidation directed by carboxylic acids can overcome these challenges to yield γ-lactones in high enantiomeric excess (up to 99%) using hydrogen peroxide as oxidant and a Brønsted acid additive under mild conditions and short reaction times. Coordination of the carboxylic acid group to the bulky Mn complex ensures the rigidity needed for high enantioselectivity and dictates the outstanding γ site-selectivity. When the substrate contains nonequivalent γ-methylenes, the site-selectivity for lactonization can be rationally predicted on the basis of simple C-H activation/deactivation effects exerted by proximal substituents. In addition, discrimination of diastereotopic C-H bonds can be modulated by catalyst design, with no erosion of enantiomeric excess. The potential of this reaction is illustrated in the concise synthesis of a tetrahydroxylated bicyclo[3.3.1]nonane enabled by two key, sequential γ-C-H lactonizations, with the latter that fixes the chirality of five stereogenic centers in one step with 96% ee.