Superoxide Production by the Mitochondrial Respiratory Chain

This mini-review describes the role of different mitochondrial components in the formation of reactive oxygen species under normal and pathological conditions and the effect of inhibitors and uncouplers on superoxide formation.     

Possible accumulation of non-active molecules of catalase and superoxide dismutase in S. cerevisiae cells under hydrogen peroxide induced stress

The effect of hydrogen peroxide on the activities of catalase and superoxide dismutase (SOD) in S. cerevisiae has been studied under different experimental conditions: various H₂O₂ concentrations, time exposures, yeast cell densities and media for stress induction. The yeast treatment with 0.25–0.50 mM H₂O₂ led to an increase in catalase activity by 2–3-fold. At the same time, hydrogen peroxide caused an elevation by 1.6-fold or no increase in SOD activity dependently on conditions used. This effect was cancelled by cycloheximide, an inhibitor of protein synthesis in eukaryotes. Weak elevation of catalase and SOD activities in cells treated with 0.25–0.50 mM H₂O₂ found in this study does not correspond to high level of synthesis of the respective enzyme molecules observed earlier by others. It is well known that exposure of microorganisms to low sublethal concentrations of hydrogen peroxide leads to the acquisition of cellular resistance to a subsequent lethal oxidative stress. Hence, it makes possible to suggest that S. cerevisiae cells treated with low sublethal doses of hydrogen peroxide accumulate non-active stress-protectant molecules of catalase and SOD to survive further lethal oxidant concentrations.     

The stimulatory effect of negative air ions and hydrogen peroxide on the activity of superoxide dismutase

The activity of erythrocyte cytosolic superoxide dismutase from rat, bovine, man and duck was considerably increased when measured after preparation or incubation in media pretreated with negative air ions (mostly superoxide) from electroeffluvial ion generator. 0.5–1.0 μM H₂O₂ was found in incubation medium after treatment with air ions. The stimulatory effect of air ions on superoxide dismutase activity was mimicked by addition of 0.5–6 μM H₂O₂. The primary physicochemical mechanism of beneficial biological action of negative air ions is suggested to be related to the stimulation of superoxide dismutase activity by micromolar concentrations of H₂O₂.     

The effect of exogenous spermidine on superoxide dismutase activity,H<Subscript>2</Subscript>O<Subscript>2</Subscript> and superoxide radical level in barley leaves under water deficit conditions

Barley (Hordeum vulgare) seedlings were treated with spermidine prior to water deficit to determine whether this polyamine is able to affect the activity of superoxide dismutase -SOD (EC 1.15.1.1) responsible for hydrogen peroxide and superoxide radical level. Short-term dehydration (24h) resulted in decrease of the SOD specific activity and a distinct increase in the superoxide anion and hydrogen peroxide contents. Polyamine treatment caused a substantial reduction in the contents of these two stress-raised reactive oxygen species and thereby lowered the oxidative stress in plant cells. Antioxidant system as an important component of the water-stress-protective mechanism can be changed by polyamines, able to moderate the radical scavenging system and to lessen in this way the oxidative stress.     

Reactive oxygen species are involved in pollen tube initiation in kiwifruit

The role of reactive oxygen species (ROS) during pollen tube growth has been well established, but its involvement in the early germination stage is poorly understood. ROS production has been reported in germinating tobacco pollen, but evidence for a clear correlation between ROS and germination success remains elusive. Here, we show that ROS are involved in germination and pollen tube formation in kiwifruit. Using labelling with dihydrofluorescein diacetate (H(2) FDA) and nitroblue tetrazolium (NBT), endogenous ROS were detected immediately following pollen rehydration and during the lag phase preceding pollen tube emergence. Furthermore, extracellular H(2) O(2) was found to accumulate, beginning a few minutes after pollen suspension in liquid medium. ROS production was essential for kiwifruit pollen performance, since in the presence of compounds acting as superoxide dismutase/catalase mimic (Mn-5,10,15,20-tetrakis(1-methyl-4-pyridyl)21H,23H-porphin, Mn-TMPP) or as NADPH oxidase inhibitor (diphenyleneiodonium chloride, DPI), ROS levels were reduced and pollen tube emergence was severely or completely inhibited. Moreover, ROS production was substantially decreased in the absence of calcium, and by chromium and bisphenol A, which inhibit germination in kiwifruit. Peroxidase activity was cytochemically revealed after rehydration and during germination. In parallel, superoxide dismutase enzymes, particularly the Cu/Zn-dependent subtype - which function as superoxide radical scavengers - were detected by immunoblotting and by an in-gel activity assay in kiwifruit pollen, suggesting that ROS levels may be tightly regulated. Timing of ROS appearance, early localisation at the germination aperture and strict requirement for germination clearly suggest an important role for ROS in pollen grain activation and pollen tube initiation.     

Detoxification of SO2 derivatives in chloroplasts ofHardwickia binata

Intact chloroplasts isolated from sulphur dioxide fumigatedHardwickia binata leaves showed inhibition of PS II electron transport activity without any significant effect on photosystem I. Sulphur dioxide exposed leaves accumulated more hydrogen peroxide than those from non-fumigated plants and this was caused by increase in superoxide radical production. Hydrogen peroxide formation was inhibited by addition of cytochrome C and superoxide disrnutase. In sulphur dioxide fumigated leaves, increase in superoxide dismutase activity showed resistance to sulphite toxicity. The localization of ascorbate peroxidase, glutathione reductase and dehydroascorbate reductase activities in chloroplasts provide evidence for the photogeneration of ascorbate. The scavenging of hydrogen peroxide in chloroplast due to ascorbate regenerated from DHA by the system: PS I → Fd → NADP → glutathione. The system can be considered as a means for preliminary detoxification of sulphur dioxide by chloroplasts     

Commentary: Oxygen Radicals,A Failure Or A Success of Evolution?

Oxygen radicals are no doubt involved in the development of many pathological states. Nevertheless, the possibility that oxygen radical production was selected for during biological evolution in order to perform useful roles in relation to cellular metabolism is contemplated; previous data on this subject are briefly reviewed. The concept of an “oxygen radical cycle” is proposed as a useful theoretical model.     

Commentary: Oxygen Radicals, A Failure Or A Success of Evolution?

Oxygen radicals are no doubt involved in the development of many pathological states. Nevertheless, the possibility that oxygen radical production was selected for during biological evolution in order to perform useful roles in relation to cellular metabolism is contemplated; previous data on this subject are briefly reviewed. The concept of an “oxygen radical cycle” is proposed as a useful theoretical model.     

Seasonal changes in antioxidant level of Scots pine (Pinus sylvestris L.) needles exposed to industrial pollution. II. Enzymatic scavengers activities

The involvement of enzymic antioxidant system, superoxide dismutase, guaiacol peroxidase, ascorbate peroxidase in defense reaction to environmental stress evoked by air and soil pollution, was seasonally studied on three populations of Scots pine (Pinus sylvestris L.) growing on experimental areas close two industrial objects in Poland. The first of them (Luboón) is localised near a phosphate fertiliser factory, the second (Głogów) near a copper foundry, and control stand is placed in Kórnik. Głogów is the most polluted site, where in 1998 monthly mean daily concentrations was: SO₂ - 17 μg·m⁻³, NO_x- 12 μg·m⁻³ and dust containing heavy metals (Cu, Pb, Cd) - 29 μg·m⁻³. Trees in Luboń were influenced for many years by high concentration of SO₂ and fluor compounds. Few years ago emissions were markedly reduced, but changes in the soil (low pH and high concentration of aluminium ions) still influence the growth of trees. In needles of two populations: 3 (Russia) and 8 (Poland), from the polluted sites Głogów and Luboń, activities of superoxide dismutase (SOD) and guaiacol peroxidase (PO) were significantly higher compared to Kórnik. However, in one population (16 - Slovakia), such dependance was not evident. Activity of ascorbate peroxidase (AP) measured in winter was also higher in needles from polluted sites. The results indicated that the sensitivity of free radical scavenging system in Scots pine needles differs among populations.     

家蚕胚后发育中过氧化氢的代谢及其意义(英文)

活性氧参与生物体内复杂的代谢过程。本文对它在家蚕个体发育过程中的生物学功能进行了初步探讨。 取１岁龄家蚕蛹分别注射Ｈ２Ｏ２、脱皮激素（Ｅｃｄｎ）、保幼激素（ＪＨ）和还原型谷胱苷肽（ＧＳＨ）,培养;定期取样测定家蚕体内Ｈ２Ｏ２含量。 对家蚕整个幼虫期（Ｆｉｇ．１）,尤其是大眠期（Ｆｉｇ．２）、化蛹期（Ｔａｂｌｅ１）、蛹期（Ｆｉｇ．３－ａ,ｂ,ｃ）以及成虫期（Ｆｉｇ．４, Ｔａｂｌｅ ２）的研究结果表明,家蚕体内Ｈ２Ｏ２代谢具有如下特点：（１）入眠、化蛹、化蛾和死亡前Ｈ２Ｏ２含量都显著下降;（２）幼虫期１－３龄Ｈ２Ｏ２含量逐步下降,４～５龄Ｈ２Ｏ２含量回升,蛹期和成虫期Ｈ２Ｏ２含量与４～５龄接近;（３）每个龄期的中期Ｈ２Ｏ２含量最高;（４）ＣＡＴ活性与Ｈ２Ｏ２含量呈负相关变化,前者迟于后者;另外,ＣＡＴ活性远远大于ＳＯＤ活性;（５）Ｅｃｄｎ、ＧＳＨ处理可以降低家蚕蛹期Ｈ２Ｏ２含量,并使其提前下降,ＪＨ、Ｈ２Ｏ２处理含量下降,并相应地提早推迟化蛾;（６）成虫期雄蛾Ｈ２Ｏ２含量、ＳＯＤ和ＣＡＴ活性都显著高于同时期雌蛾。家蚕体内Ｈ２Ｏ２含量的变化与其发育密切相关。Ｈ２Ｏ２含量下降是变态的信号;家蚕成虫期Ｈ２Ｏ２ 在性别上的     

Salicylic acid induced changes on antioxidant capacity,pigments and grain yield of soybean genotypes in water deficit condition

Salicylic acid (SA) plays an important role in the regulation of plant growth and development in response to water deficit. The effect of SA (0, 0.4 and 0.8?mM) on some physiological parameters of three soybean genotypes was investigated in three irrigation schedules included (85%, 65% and 45% of field capacity) during 2014–2015. Results showed that water deficit decreased stomatal conductance, leaf area index, relative water content, membrane stability index, yield components and grain yield particularly in L17 genotype. Activities of superoxide dismutase, ascorbate peroxidase and concentration of hydrogen peroxide, proline and total protein were increased in response to water deficit as well as SA applications. SA inhibited catalase activity resulting in increased hydrogen peroxide accumulation in soybean genotypes. Application of 0.4?mM SA decreased the adverse effects of water deficit in soybean genotypes by elevation of antioxidant enzymes activity and reducing malondialdehyde formation especially in Williams genotype.     

过氧化氢参与了黑暗诱导的盐地碱蓬叶片甜菜红素积累

该文比较研究了黑暗和光照条件下C₃盐生植物盐地碱蓬(Suaeda salsa)叶片甜菜红素积累和H₂O₂含量及其抗氧化酶活性的关系,实验分析了甜菜红素体外抗氧化性能,以期揭示诱导盐地碱蓬甜菜红素积累的可能机制以及甜菜红素积累的生理生态意义。结果表明:暗期处理和营养液中加入一定浓度的H₂O₂都明显促进盐地碱蓬叶片H₂O₂含量、甜菜红素的含量、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)的活性,而且叶片中 H₂O₂含量与甜菜红含量、SOD和CAT活性具有正相关性;盐地碱蓬甜菜红素体外清除羟自由基的能力明显强于维生素C,而清除超氧阴离子能力低于维生素C。这些结果表明:黑暗作为一种环境胁迫因子诱导盐地碱蓬叶片甜菜红素的积累可能是由自由基介导的,甜菜红素的积累可能与提高植物的抗氧化能力有关。     

Microbial adaptation to hydrogen peroxide and biodegradation of aromatic hydrocarbons

This research investigated microbial responses to bioremediation with hydrogen peroxide (H₂O₂) as a supplemental oxygen source. Columns containing aquifer material from Traverse City, MI, USA, were continuously supplied with benzene, toluene, ethylbenzene, o-xylene and m-xylene (BTEX) and H₂O₂ in increasing concentration. The microbial responses studied were changes in microbial numbers, community structure, degradative ability, and activity of catalase and superoxide dismutase (SOD). Both adaptation to H₂O₂ and stress-related consequences were observed. Adaptation to H₂O₂ was demonstrated by increased catalase and SOD activity during the course of the experiment. The microbial community in the untreated aquifer material used in the columns consisted primarily of Corynebacterium sp and Pseudomonas fluorescens. Following amendment with 500 mg L⁻¹ H₂O₂, the column inlet was dominated by P. fluorescens with few Corynebacterium sp present; Xanthomonas maltophilia dominated the middle and outlet sections. Dimethyl phenols detected in the effluent of two of the biologically active columns were probably metabolic products. The ratio of oxygen to BTEX mass consumed was approximately 0.3 before H₂O₂ addition, 0.7 following 10 mg L⁻¹ H₂O₂ supplementation, and 2.6 over the course of the experiment. Abiotic decomposition H₂O₂ was observed in a sterile column and impeded flow at a feed concentration of 500 mg L⁻¹ H₂O₂. Increasing the BTEX concentration supplied to the biologically active columns eliminated flow disruptions by satisfying the carbon and energy demand of the oxygen evolved by increasing catalase activity. Received 15 February 1996/ Accepted in revised form 15 July 1996     

马缨丹叶提取液对水葫芦叶片中超氧物歧化酶活性和过氧化氢积累的影响

水葫芦[Eichhornia crassipes（Mart）Solms]是世界上繁殖最快、危害最严重的多年生水生杂草之一。为了避免化学除草剂对水体的污染,生物防治已成为当前水葫芦治理的重要方向。马缨丹（Lantana camara）是马鞭草科的一种植物,其叶片提取物对水葫芦有很强的毒性。研究结果表明：经马缨丹叶提取液处理的水葫芦叶片中,超氧物歧化酶（SOD）活性与H2O2浓度均显著升高,但过氧化氢酶的活性受到抑制,膜脂过氧化程度明显增加。H2O2的组织化学染色结果表明H2O2在气孔细胞中有异常高的积累,H2O2过量产生同时导致水葫芦叶片失绿与细胞死亡。因此,氧胁迫可能是马缨丹提取液对水葫芦毒害的主要原因之一。