Increase In Reactive Oxygen Species Content Research Articles

Oxidative stress in the skin: Impact and related protection.

Skin, our first interface to the external environment, is subjected to oxidative stress caused by a variety of factors such as solar ultraviolet, infrared and visible light, environmental pollution, including ozone and particulate matters, and psychological stress. Excessive reactive species, including reactive oxygen species and reactive nitrogen species, exacerbate skin pigmentation and aging, which further lead to skin tone unevenness, pigmentary disorder, skin roughness and wrinkles. Besides these, skin microbiota are also a very important factor ensuring the proper functions of skin. While environmental factors such as UV and pollutants impact skin microbiota compositions, skin dysbiosis results in various skin conditions. In this review, we summarize the generation of oxidative stress from exogenous and endogenous sources. We further introduce current knowledge on the possible roles of oxidative stress in skin pigmentation and aging, specifically with emphasis on oxidative stress and skin pigmentation. Meanwhile, we summarize the science and rationale of using three well-known antioxidants, namely vitamin C, resveratrol and ferulic acid, in the treatment of hyperpigmentation. Finally, we discuss the strategy for preventing oxidative stress-induced skin pigmentation and aging.

Enhanced anti-Escherichia coli properties of Fe-doping in MgO nanoparticles.

Hetero-elements doping is an effective way to modify the composition and nanostructure of metal oxides. These modifications could lead to changes in physical and chemical properties correspondingly. In this study, Fe-doped MgO nanoparticles (NPs) were synthesized by simple calcination method in air. The antibacterial activity of MgO NPs against Escherichia coli (E. coli, ATCC 25922) was significantly improved as shown by the bactericidal efficacy test results. According to X-ray diffraction (XRD) results, Fe was successfully doped into MgO lattice and mainly adopted interstitial doping. The Fe-doping led to increased oxygen vacancies and OA content (from 13.5% to 41.3%) on MgO surface, which may have facilitated the reactive oxygen species (ROS) generation and bacteria death. The wrinkled and sunken E. coli surface after contact with Fe-doped MgO NPs also confirmed the existence of adsorption damage mechanism. Thus, the antibacterial activity enhancement against E. coli was originated from the synergistic effect of increased ROS concentration and the interaction with Fe-doped MgO NPs.

Vigor difference during storage and germination in Indian mustard explained by reactive oxygen species and antioxidant enzymes

Canola-type genotypes in Indian mustard (Brassica juncea) are a new kind of quality resource developed for their low levels of erucic acid (<2%) and glucosinolate (<30 μmole/g defatted meal) contents. Single-zero (low erucic acid) and double-zero (low erucic acid and glucosinolate content) genotypes of Indian mustard have less vigor. Conventional genotypes (high erucic acid and glucosinolate contents) havea significantly higher seedling vigor index-II (SVI-II) and single-zero genotypes have a significantly higher SVI-I, whereas double-zero genotypes have been observed to have a significantly lower SVI-I and SVI-II. To know the possible reasons for the differences in vigor, the seed quality parameters, reactive oxygen species (ROS) contents (superoxide radicals (O2−·) and hydrogen peroxide), lipid peroxidation, and antioxidant enzyme activity were examined. In the dry seeds, the conventional genotypes revealed lower ROS contents and higher catalase and peroxidase enzyme activity. This trend was reversed in the double-zero genotypes, which could be the reason why they were more susceptible to oxidative damage. During seed germination, an increase in the ROS contents, and corresponding increase in antioxidant enzyme activity, was noticed, which was highest in the conventional genotypes, followed by the single-zero genotypes. Double-zero genotypes showed the lowest increase in ROS contents and antioxidant enzyme activity during this period. This meant that the required attributes were met for maintaining oxidative balance within the cells and triggering physiological activities to reach high vigor. This study proposed 2 causes for the poor vigor of the double-zero genotypes; first, in the dry seeds, the ROS remained high due to low antioxidant activity (ROS scavengers) and the second was less generation of O2−· during germination.

Synthesis, characterization and biological activity of cefazolin sodium dendrimer complexes

The potent bacterial infections serve as the primary cause of mortality due to the absence of novel antibacterial therapy. The present investigation synthesized citric acid dendrimers through the divergent method that serves as a suitable platform in fulfilling the prerequisites of drug delivery. The cytotoxicity studies revealed 5.4 ± 0.3% of cell viability at 0.5 μg/ml and 35±0.3% at 300 μg/ml after 36 h. The IC50 values on Human Alveolar Epithelial (HAE) cells for unmodified dendrimers were 1.36±0.06 mg ml−1while for PEG CZ G5 dendrimers were 35.19±0.15 mg/mlwith 9 ± 0.18% hemolysis. The significant differences were due to the variations in drug content and PEG shield density at the terminal surface. The Reactive Oxygen Species (ROS) uptake and dichlorofluorescein intensity for PEG CZ G2 dendrimers was 24.15 ± 1.24% and 42.3 ± 0.12%whichincreased significantly with the degree of pegylation and revealed 72.5 ± 1.03% and 79.2 ± 0.24%for PEG CZ G5 dendrimers. The increased ROS concentrations altered the mitochondrial functioning and served as a proof for antibacterial effect. Drug release pattern when heuristically fitted into various kinetic models specified zero-order release with non-fickian diffusion. Antibacterial investigations and pharmacokinetic studies revealed that the synthesized generations were quite effective against various bacterial pathogens with optimized concentrations.

Effect of Glucose Metabolism-Associated Protein-1 on Exendin-4-Treated Pancreatic Islet Cell Function

Exendin-4 regulates blood sugar. Glucose metabolism-associated protein-1 (GMRP-1) regulates islet cell function. Therefore, this paper intends to analyze the effect of GMRP-1 on Exendin-4treated islet cells. The islet cell MIN6 cells were separated into control group, Exendin-4 group, GMRP-1 overexpressing+ Exendin-4 group, and GMRP-1 siRNA+ Exendin-4 group followed by analysis of the expression of GMRP-1 by quantitative real-time PCR and Western blot, cell proliferation by MTT, cell apoptosis by flow cytometry, Bcl-2, Bax, Fas and Fas-L expression by real-time PCR, as well as caspase-3 activity, reactive oxygen species (ROS) and superoxide dismutase (SOD) activity. Exendin-4 and GMRP-1 overexpression+ Exendin-4 significantly increased GMRP-1 expression and promoted cell proliferation, decreased apoptotic rate and Caspase-3 activity, increased Bcl-2 and Fas-L expression, reduced Fas and Bax expression, as well as decreased ROS generation and increased SOD activity (P < 0 05), and the changes in GMRP-1 overexpression+ Exendin-4 group was more significant (P < 0 01). However, GMRP-1 siRNA+ Exendin-4 group significantly down-regulated GMRP-1 expression, decreased MIN6 cell prolifer- ation, increased cell apoptosis and Caspase-3 activity, decreased Bcl-2 and Fas-L expression, elevated Fas and Bax expression, increased ROS content and decreased SOD activity compared to control group and Exendin-4 group (P < 0 05). Up-regulation of GMRP-1 expression promoted Exendin-4-induced proliferation and inhibited apoptosis of islet cells. Down-regulation of GMRP-1 expression reversed Exendin-4's effect on islet cells.

Single and repeated low-dose UVB radiation exposures affect the visual system

The visual system is an important biological indicator of effects induced by ultraviolet (UV) radiation. However, research has extensively investigated the effects of high-dose UV radiation in a single exposure, thus, the differential of this work was to investigate the effects of UVB radiation in low doses in single and repeated exposure. Therefore, we investigated the effects of repeated exposure to environmental UVB doses (0.09 J/cm2) on the retina and optic lobes of the crab Neohelice granulata. We evaluated the reactive oxygen species (ROS) concentration, antioxidant capacity against peroxyl radicals (ACAP) levels, catalase (CAT) and glutathione S-transferase (GST) activities and lipoperoxidation (LPO) levels and performed histological analysis. The crabs were exposed to UVB radiation for 1 or 60 days, while the control group was exposed to visible light. In the retina region, increases in ROS concentration and CAT and GST activities after the single exposure were observed. After 60 days of exposure, we observed an increase in ACAP levels. In the optic lobes, we observed an increase in GST activity and a decrease in LPO levels after the single exposure. However, we observed an increase in ROS concentration after 60 days of exposure. Moreover, after 60 days of exposure, infiltrating hemocytes in the retina and disorganization in neuron cell bodies of the external medulla were observed. In this sense, single and repeated exposure to low doses of UVB radiation induced changes in oxidative status and inflammatory process in the visual system of the crab Neohelice granulata.

Chlorothalonil causes redox state change leading to oxidative stress generation in Danio rerio

A diverse range of chemicals are used in agriculture to increase food production on a large scale, and among them is the use of pesticides such as chlorothalonil, a broad-spectrum fungicide used in the control of foliar fungal diseases. This study aimed to elucidate the effects of chlorothalonil on biochemical biomarkers of oxidative stress in tissues of the fish Danio rerio. To achieve this, animals were exposed for 4 and 7 days, to nominal concentrations of chlorothalonil at 0 μg/L (DMSO, 0.001%), 0.1 μg/L and 10 μg/L, and after the exposure period, the tissues (gills and liver) were removed for biochemical analysis. Antioxidant capacity against peroxyl radicals (ACAP) and enzyme activities, such as superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST) and glutamate cysteine ligase (GCL), were evaluated in both tissues. In addition, the concentration of reactive oxygen species (ROS), reduced glutathione (GSH) and lipid peroxidation (LPO) levels were also analysed. A significant increase in ROS concentration, ACAP levels, GST and GCL activities and a significant reduction of LPO levels in gills exposed to the highest concentration were observed after 4 days. However, there was a significant reduction of ACAP and CAT activity, as well as a significant increase of GST activity and LPO levels in gills exposed to the lower concentration after 7 days. The liver was less affected, presenting a significant reduction in CAT activity and LPO levels after 4 days. However, a significant increase in SOD activity and LPO levels occurred after 7 days. These results indicate that chlorothalonil, after 4 days, caused activation of the antioxidant defence system in gills of animals exposed to the highest concentration. However, after 7 days, the lowest concentration of this compound caused oxidative stress in this same organ. Also, the results show that gills were more affected than the liver, probably because gills can be involved in chlorothalonil metabolisation. Therefore, it is possible that the liver could be exposed to lower chlorothalonil concentrations or less toxic metabolites due to the metabolism taking place in the gills.

Exposure to Fullerene C60 Nanoparticles Impairs Lung Mechanics and Mitochondrial Function

C60 fullerene (C60) carbon‐based nanoparticles are widely used because of their physicochemical properties, and are released into the atmosphere from anthropogenic or natural sources. Due to its small size (0.65–0.7 nm) and electronegative chemical behavior, C60 can overcome natural biological barriers and deposit onto the respiratory system. However, the literature does not fully describe its putative pulmonary burden. C60 interaction with double membrane organelles like mitochondria, housing enzyme systems that convert metabolism by‐products into usable energy (ATP) and are an important source of oxygen‐derived free radicals, has been recently described. We hypothesized that C60 impairs lung function and alters its inflammatory status via mechanisms possibly involving mitochondria. Hence, we addressed pulmonary mechanics, histology and mitochondrial function after a single exposure to C60. Our Institutional Ethics Committee approved the study (code: 155/18). Thirty‐five male BALB/c mice were randomly divided into 2 groups intratracheally (it) instilled with vehicle (0.9% NaCl + 1% Tween 80, CTRL) or C60 (1.0 mg/kg, FUL). Twenty‐four hours after exposure, 15 FUL and 8 CTRL mice were anesthetized (10 mg/kg xylazine and 120 mg/kg ketamine), paralyzed (pancuronium bromide, 0.1 mg/kg) and mechanically ventilated for the determination of lung mechanics. They were then euthanized by sectioning of abdominal aorta and vena cava; the lungs were extracted at FRC for histological processing. Results are expressed as median, 25th and 75th percentiles. FUL group showed increased lung tissue elastance (FUL=38.21, 32.43, 39.83 vs CTRL=31.63, 29.31, 33.41 cmH2O/mL, p=0.0049) and viscance (FUL=4.44, 3.72, 4.76 vs CTRL=3.73, 3.36, 3.87 cmH2O/mL, p=0.0225). In addition, lung histology disclosed increased inflammatory cell number (FUL=16.0, 14.6, 18.8 vs CTRL=9.2, 8.8, 9.6 10−3/μm2 cells, p=0.0022) and alveolar collapse (FUL=11.33, 10.34, 13.79 vs CTRL=5.78, 4.69, 7.71%; p=0.0286), septal thickening and pulmonary edema. The remaining 6 FUL and 6 CTRL mice were expertly euthanized by cervical dislocation. Mitochondrial function expressed reduction in state 1 respiration in the presence of pyruvate‐malate substrates [FUL=3.0±1.14 vs CTRL=4.46±0.9 (SEM) nmol O2/min/mg protein, p=0.0210], ATP production (FUL=122.6±18 vs CTRL=154.5±14 μmol/100 μg protein, p=0.0340), and higher generation of reactive oxygen species (ROS) (FUL 733.1±169.32 vs CTRL=486.39±73.1 nmol/100 μg protein, p=0.0313). In conclusion, exposure to fullerene C60 impaired lung mechanics and mitochondrial function, increased ROS concentration, and triggered pulmonary tissue inflammation.Support or Funding InformationCNPq, FAPERJ, FINEP, CAPES

ROS-Driven Oxidative Modification: Its Impact on Chloroplasts-Nucleus Communication.

As a light-harvesting organelle, the chloroplast inevitably produces a substantial amount of reactive oxygen species (ROS) primarily through the photosystems. These ROS, such as superoxide anion, hydrogen peroxide, hydroxyl radical, and singlet oxygen, are potent oxidizing agents, thereby damaging the photosynthetic apparatus. On the other hand, it became increasingly clear that ROS act as beneficial tools under photo-oxidative stress conditions by stimulating chloroplast-nucleus communication, a process called retrograde signaling (RS). These ROS-mediated RS cascades appear to participate in a broad spectrum of plant physiology, such as acclimation, resistance, programmed cell death (PCD), and growth. Recent reports imply that ROS-driven oxidation of RS-associated components is essential in sensing and responding to an increase in ROS contents. ROS appear to activate RS pathways via reversible or irreversible oxidation of sensor molecules. This review provides an overview of the emerging perspective on the topic of “oxidative modification-associated retrograde signaling.”

Влияние нанокомпозита селена и арабиногалактана на колонизацию растений картофеля in vitro возбудителем кольцевой гнили

It has been previously shown that the chemically synthesized nanocomposite of selenium with arabinogalactan (NC Se/AG) is characterized by antibacterial effect upon the agent of ring rot – gram-positive bacterium Clavibacter sepedonicus (Cms), with the NC Se/AG having no negative effect on potato plants. In the present paper, it has been found that, 1 hour after the treatment of the NC Se/AG, a substantial elevation of lipid peroxidation products was observed in potato root tissues. This supports earlier results on the increase in reactive oxygen species (ROS) production in potato root tissues under the influence of NC Se/AG. It is proposed that the increased ROS content in potato may inhibit pathogen colonization of plants. This has been tested by seeding homogenised plant tissues of various potato zones (roots, stems, shoot apex zone) onto the nutrient medium. In plants infected with Cms and untreated with the NC, the number of colony forming units (CFUs) of Cms has been shown to be numerous both in potato culture medium and in root and stem tissues. In shoot apex zone of such plants, it has been revealed, bacteria also present, but in smaller quantities. Similar data have been obtained by seeding homogenised tissues from roots and stems of potato plants treated with the NC followed by infection with Cms. However, seeding from shoot apex zones of the plants has been given 4 times less CFUs than from potato plants not treated with the NC. The effect of the NC Se/AG upon the pathogen colonization of plants appears to depend on the titre of the microorganism. In shoot apex zone of plants, characterized with small number of CFUs of Cms, the pathogen growth has been decreased. For the first time, Cms bacteria in potato plant tissues in vitro have been visualized with the aid of scanning microscopy.

Активные формы кислорода в водных средах (обзор)

The problems of the presence of reactive oxygen species (ROS) in natural aquatic environments and living organisms are considered. The basic properties of ROS are given, which provide the features of their behavior. The main attention is focused on the analysis of data on the state of water systems with a slightly increased ROS content compared to equilibrium values.

Soybean glycinin caused NADPH-oxidase-regulated ROS overproduction and decreased ROS elimination capacity in the mid and distal intestine of juvenile grass carp (Ctenopharyngodon idella)

Soybean glycinin could increase reactive oxygen species (ROS) content and cause damage in the intestine of Jian carp. However, related mechanisms are largely unknown. To test the hypothesis that glycinin increases intestinal ROS content by increasing ROS generation and decreasing ROS elimination capacity, juvenile grass carp (Ctenopharyngodon idella) were distributed into 3 treatments, fed with control, 8% glycinin or 8% glycinin+1.2% glutamine diets for 7 weeks, and intestinal oxidative damage, ROS content, intestinal ROS generation and elimination parameters were measured. Compared with control treatment, fish fed with glycinin diet had higher ROS, protein carbonyl (PC) and malondialdehyde (MDA) in the mid intestine (MI) and distal intestine (DI) (P < 0.05) rather than proximal intestine (PI) (P ≥ 0.05). For ROS generation parameters, compared with control treatment, dietary glycinin increased NADPH oxidase (NOX) activities, NOX1 and NOX2 protein abundance, and NOX1, NOX2, NOX organizer (NOXO) 1b, NOX activator (NOXA) 1, p47phox and p67phox mRNA abundance (P < 0.05) of MI, increased NOX activities, NOX1 protein, NOXO1b, NOXA1 and p22phox mRNA abundance (P < 0.05) of DI, and decreased NOX activities and all the mRNA abundance of NOX family genes measured (P < 0.05) except NOX4, NOXO1a and p47phox in the PI (P ≥ 0.05). For ROS elimination parameters, compared with control treatment, dietary glycinin decreased total and nuclear Nrf2 protein abundance, total antioxidant capacity (T-AOC), anti-superoxide anion (ASA), anti-hydroxy radical (AHR), CuZn-SOD, catalase, glutathione (GSH) peroxidase (GPx), GSH-S-transferase (GST) and GSH reductase (GR) activities of MI (P < 0.05), total and nuclear Nrf2 protein abundance, T-AOC, ASA, AHR, CuZn-SOD, Mn-SOD, CAT, GPx and GST activities (P < 0.05) of DI and T-AOC, ASA, CuZn-SOD, Mn-SOD and catalase activities (P < 0.05) of PI. Compared with glycinin treatment, glycinin + glutamine treatment decreased ROS, PC and MDA of MI (P < 0.05) but neither in PI nor DI of grass carp (P ≥ 0.05). Concluded, this study showed that (1) glycinin increased ROS generation related to NOX signaling pathway and decreased ROS elimination capacity related to the Nrf2 translocation in the MI and DI, which lead to the increased ROS content; (2) glycinin decreased both ROS generation and ROS elimination capacity in the PI of fish, which lead to the unchanged ROS content; (3) Glutamine could protect glycinin-induced oxidative stress mainly in the MI.

Zearalenone induces apoptosis in bovine mammary epithelial cells by activating endoplasmic reticulum stress

Zearalenone (ZEA) is a common mycotoxin produced by fungi within the genus Fusarium. However, few studies have examined the direct effects of the toxin on the mammary glands. In the present study, the effects of ZEA treatment on bovine mammary epithelial cells (MAC-T) from dairy cows were investigated. The cells were treated with different concentrations of ZEA to evaluate the effect of the toxin on cell viability, intracellular reactive oxygen species (ROS) concentrations, mitochondrial membrane potential, endoplasmic reticulum (ER) stress, and the expression of apoptosis-related genes. The results indicated that different concentrations (5, 10, 15, 20, 25, 30, 50, 60, or 100 μM) of ZEA were able to inhibit growth of MAC-T cells. After exposing the MAC-T cells to 30 μM ZEA, compared with the control group, ROS levels increased, mitochondrial membrane potential decreased, and mRNA expression of the ER-specific stress-related genes GRP78, HSP70, ATF6, EIF2A, ASK1, and CHOP was upregulated in the ZEA-treated group. Further, we analyzed the increase in apoptotic rate by flow cytometry. At the mRNA level, compared with the control group, the expression of the apoptosis-promoting gene BAX was increased in the ZEA-treated group, the expression of the inhibitory gene BCL2 decreased, and the expression of the gene CASP3 increased. We observed a significant increase in caspase-3 activity in ZEA-treated MAC-T cells. Furthermore, the apoptotic rate of the cells in the ZEA group treated with 4-phenylbutyric acid (ER stress inhibitor) decreased and the mRNA expression levels of ER stress markers GRP78 and CHOP decreased. Compared with the ZEA treatment group, the mRNA expression level of the apoptosis-related gene BAX was decreased and the expression level of BCL2 was increased in the ZEA + 4-phenylbutyric acid cotreatment group. These findings indicate that ZEA-induced ER stress increases apoptosis in MAC-T cells. The treatment of MAC-T cells with ZEA reduced cell viability, increased ROS content, decreased mitochondrial membrane potential, increased ER stress marker expression, and induced apoptosis.

Protamine Sulfate Induces Mitochondrial Hyperpolarization and a Subsequent Increase in Reactive Oxygen Species Production.

Protamine sulfate (PS) is widely used in heart surgery as an antidote for heparin, albeit its pharmacological effects are not fully understood and applications are often accompanied by unwanted side effects. Here we show the effect of PS on mitochondrial bioenergetics profile resulting in mitochondrial reactive oxygen species (ROS) production. Polarographic measurements were performed in parallel to membrane potential and ROS measurements by FACS analyzer using tetramethylrhodamine ethyl ester and MitoSOX fluorescent dyes, respectively. PS inhibited intact rat heart mitochondrial respiration (stimulated by ADP) to 76% (P < 0.001) from the baseline of 51.6 ± 6.9 to 12.4 ± 2.3 nmol O2⋅min-1⋅ml-1 The same effect was found when respiration was inhibited by antimycin A (101.0 ± 8.9 vs. 38.0 ± 9.9 nmol O2 ⋅min-1⋅ml-1, P < 0.001) and later stimulated by substrates of cytochrome oxidase (CytOx) i.e., ascorbate and tetramethyl phenylene diamine, suggesting that PS exerted its effect through inhibition of CytOx activity. Furthermore, the inhibition of mitochondrial respiration by PS was concentration dependent and accompanied by hyperpolarization of the mitochondrial membrane potential (Δψ m), i.e., 18% increase at 50 µg/ml and an additional 3.3% increase at 250 µg/ml PS compared with control. This effect was associated with a strong consequent increase in the production of ROS, i.e., 85% and 88.6% compared with control respectively. We propose that this excessive increase in ROS concentrations results in mitochondrial dysfunction and thus might relate to the "protamine reaction," contributing to the development of various cardiovascular adverse effects.

Role of Nrf2 in the antioxidation and oxidative stress induced developmental toxicity of honokiol in zebrafish

Honokiol, the main bioactive component of Magnolia officinalis, has a variety of pharmacological actions. However, its toxicity has rarely been reported. According to previous studies performed in our laboratory, honokiol microemulsion has embryo developmental toxicity. For further exploration, Zebrafish embryos were exposed to different doses of honokiol microemulsion to record the rates of mortality, malformation, and hatching. We found that high doses of honokiol microemulsion (0.6 and 0.9 μg/ml) increased mortality, inhibited hatching, caused malformation and reduced swimming activities. The low-dose group (0.15 and 0.30 μg/ml) had decreased production of reactive oxygen species (ROS), but the high-dose group had inhibited superoxide dismutase (SOD) enzyme activity and increased ROS content. The mRNA expression of sod1, sod2, catalase(cat), and heme oxygenase 1 (ho1) was up-regulated at low doses but down-regulated at high doses. The nuclear factor E2-related factor 2 (Nrf2) mRNA expression increased at low doses but decreased at high doses. After knocking down Nrf2 in zebrafish embryos, the rates of mortality and malformation were markedly increased and the hatching rate was significantly decreased. These results suggest that honokiol has antioxidative effects at low doses but causes embryo-developmental toxicity at high doses, and the Nrf2 gene may play a pivotal role in regulating these processes.

Lineage Tracing Reveals a Subset of Reserve Muscle Stem Cells Capable of Clonal Expansion under Stress.

Stem cell heterogeneity is recognized as functionally relevant for tissue homeostasis and repair. The identity, context dependence, and regulation of skeletal muscle satellite cell (SC) subsets remains poorly understood. We identify a minor subset of Pax7+ SCs that is indelibly marked by an inducible Mx1-Cre transgene invivo, is enriched for Pax3 expression, and has reduced ROS (reactive oxygen species) levels. Mx1+ SCs possess potent stem cell activity upon transplantation but minimally contribute to endogenous muscle repair, due to their relative low abundance. In contrast, a dramatic clonal expansion of Mx1+ SCs allows extensive contribution to muscle repair and niche repopulation upon selective pressure of radiation stress, consistent with reserve stem cell (RSC) properties. Loss of Pax3 in RSCs increased ROS content and diminished survival and stress tolerance. These observations demonstrate that the Pax7+ SC pool contains a discrete population of radiotolerant RSCs that undergo clonal expansion under severe stress.

Toxicity of binary mixtures of pesticides to the marine microalgae Tisochrysis lutea and Skeletonema marinoi: Substance interactions and physiological impacts

This study screened binary mixtures of pesticides for potential synergistic interaction effects on growth of the marine microalgae Tisochrysis lutea and Skeletonema marinoi. It also examined the single and combined effects of three of the most toxic substances on microalgal physiology.Single substances were first tested on each microalgal species to determine their respective EC50 and concentration-response relationships. The toxicity of six and seven binary mixtures was then evaluated in microplate experiments on the growth of T. lutea and S. marinoi, respectively, using two mixture modelling approaches: isobolograms and the MIXTOX tool, based on Concentration Addition (CA) or Independent Action (IA) models. Significant cases of antagonism (for both species) and synergism (for S. marinoi) were observed for the mixtures of isoproturon and spiroxamine, and isoproturon and metazachlor, respectively.These two mixtures, together with that of isoproturon and diuron, for which additivity was observed, were further studied for their impacts on the physiology of each species. Exposures were thus made in culture flasks at three concentrations, or concentration combinations for mixtures, selected to cause 25%, 50% and 75% growth rate inhibition. The effects of the selected pesticides singly and in combination were evaluated at three perceived effect concentrations on esterase metabolic activity, relative lipid content, cytoplasmic membrane potential and reactive oxygen species (ROS) content by flow cytometry, and on photosynthetic quantum yield (ϕ’M) by PAM-fluorescence.Isoproturon and diuron singly and in mixtures induced 20–40% decreases in ϕ’M which was in turn responsible for a significant decrease in relative lipid content for both species. Spiroxamine and metazachlor were individually responsible for an increase in relative lipid content (up to nearly 300% for metazachlor on S. marinoi), as well as cell depolarization and increased ROS content. The mixture of isoproturon and metazachlor tested on S. marinoi caused a 28–34% decrease in ϕ’M that was significantly higher than levels induced by each of substances when tested alone. This strong decrease in ϕ’M could be due to a combined effect of these substances on the photosynthetic apparatus, which is likely the cause of the synergy found for this mixture.

The effects of different pharmacological agent treatments on ROS accumulation and functional protein activities in wheat endosperm PCD

Wheat (Triticum aestivum L.) is one of the top three food crops in the world. Studies have revealed that wheat endosperm development undergoes programmed cell death (PCD) process development that may be influenced by PCD. Waterlogging and exogenous hydrogen peroxide (H2O2) treatment exacerbates wheat endosperm PCD, whereas PCD acceleration is significantly inhibited by reactive oxygen species (ROS) scavengers. To explore the physiological mechanism of waterlogging resistance in wheat, the effects of exogenous H2O2, ascorbic acid (AsA), and cyclosporin A (CsA) treatment on ROS content, antioxidant enzyme activity, release of cytochrome c, and caspase-like protease activity in the endosperm of Huamai 8 (waterlogging-tolerant wheat cultivar) and Huamai 9 (waterlogging-sensitive wheat cultivar) were studied. The results showed that exogenous H2O2 treatment resulted in an increase in ROS content, antioxidant enzyme activity, mitochondrial membrane permeability, release of cytochrome c, and caspase-like protease activity in the endosperms of both wheat cultivars, which eventually exacerbated PCD. Compared to Huamai 8, the increase in ROS content in Huamai 9 was more significant, whereas changes in antioxidant enzyme activity, cytochrome c release, mitochondrial membrane permeability, and caspase-like protease activity were smaller. Exogenous AsA treatment leads to the content of H2O2 and catalase activity decrease, which could inhibit endosperm cell death to some extent. CsA treatment effectively inhibited the increase in H2O2 content, antioxidant enzyme activity, release of cytochrome c, and caspase-like protease activity caused by exogenous H2O2 treatment, which in turn inhibited cell death. In summary, exogenous H2O2 treatment aggravates endosperm PCD, and Huamai 9 exhibited higher ROS accumulation and a weaker antioxidant enzyme system under external stress, which may be the mechanisms underlying its sensitivity to waterlogging. CsA effectively inhibited the increase in ROS, antioxidant enzyme activity, cytochrome c release, and cell death. It is possible that in wheat endosperm, mitochondria in a similar way to animal mitochondria release cytochrome c regulating PCD.

Interactive effects of abscisic acid and nitric oxide on chilling resistance and active oxygen metabolism in peach fruit during cold storage.

Cold conditions can accelerate the production of reactive oxygen species (ROS), and excessive ROS may attack biological macromolecules, disrupt related signal pathways, induce oxidative stress and influence plant metabolism. The cross-talk between nitric oxide (NO) and abscisic acid (ABA) and the inhibitions by NO or ABA on oxidative damage have been reported in fruits. However, there are few reports about the roles of NO-ABA interactions in chilling stress and antioxidant defense in fruits during cold storage. This study was conducted to investigate the roles of NO, ABA and interactions between NO and ABA in response to chilling stress on peach fruit (Prunus persica (L.) Batsch, cv. 'Xintaihong'). Treatments with 15 µmol L-1 NO, 100 µmol L-1 ABA and 15 µmol L-1 NO + 5mmol L-1 sodium tungstate solution could reduce ROS content, alleviate lipid peroxidation and enhance antioxidant enzyme activities and antioxidant capacities. However, treatments with 5µmol L-1 potassium 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO), 5mmol L-1 sodium tungstate and 100 µmol L-1 ABA + 5µmol L-1 c-PTIO differentially blocked these protective effects and significantly increased ROS content and lipid peroxidation of peaches under low-temperature conditions. Application of exogenous ABA could increase the resistance to cold-induced oxidative stress by enhancing the efficiency of enzymatic and non-enzymatic systems, which were partially mediated by NO. © 2018 Society of Chemical Industry.

Вплив фунгіцидів на активність пероксидаз у Arabidopsis thaliana

Fungicides that effectively protect fruit trees, vegetable and decorative plants are widely used to control fungal diseases of important agricultural crops. All fungicides are divided into two - contact and systemic - groups. Contact fungicides contain compounds of copper or sulfur, which have a prophylactic effect. Systemic or therapeutic fungicides kill the mycelium, preventing its growth in the parenchyma of plants. Widely used systemic fungicides contain benzimidazoles and strobirulins. Although fungicides demonstrate the positive effects against fungal diseases, in some cases the negative effects of these compounds on plant growth and development were found. These effects are primarily due to the fact that fungicides represent a stress factor for plants. Under the action of stress factors, an increased amount of reactive oxygen species (ROS) is generated in plants. The increase of ROS content in the plant cell leads to oxidative stress. To counteract this stress, the mechanisms of harmful ROS detoxification are present in the plant cell. These mechanisms include, first of all, the antioxidant enzymes, like ascorbate and guaiacol peroxidases. Contact fungicides affect the antioxidant system of plants. However, the role of antioxidant enzymes in the action of systemic fungicides has not been clarified. Therefore, the aim of our study was to investigate the role of ascorbate peroxidase (APX) and guaiacol peroxidase (POD) in the response of the model plant Arabidopsis thaliana to the treatment by contact (Median) and systemic (Strobi, Topsin M) fungicides. It was found that after application of systemic fungicides Strobi and Topsin M no significant changes of APX activity occur. In contrast, in the plants treated with contact fungicide Median, APX activity increased by 46.3% compared to the control plants. Evaluation of POD activity revealed that the application of Strobi and Topsin M does not affect the activity of this enzyme. However a significant increase of POD activity by 42.6% was observed after the treatment with Median. Thus, the antioxidant system of the model plant A. thaliana specifically responds to the treatment of plants with different fungicides. It was shown that fungicides of systemic action like Strobi and Topsin M do not cause oxidative stress in plant cell. The contact fungicide Median leads to the activation of antioxidant enzymes, such as APX and POD. Key words: fungicides, reactive oxygen species (ROS), antioxidant system, APX, POD, Arabidopsis thaliana.