渗透胁迫对杧果叶片活性氧伤害的影响

杧果叶片经渗透胁迫处理后,叶水势Ψ_L下降,O₂^·产生速率和MDA含量增加,SOD、POD和CAT的活性水平与O₂^·和MDA的变化相一致。结果表明,杧果叶片的渗透胁迫损伤,是由O₂^·引发的膜脂过氧化,致使MDA含量增加,破坏细胞膜系统所致。渗透胁迫处理过程中,GSH和AsA含量下降。     

Reactive oxygen species induce apoptosis of synoviocytes in vitro. Alpha-tocopherol provides no protection

Reactive oxygen species (ROS) are released during the inflammation of the synovial membrane associated with cartilage degradation in osteoarthritis. In this work, we exposed synoviocytes to superoxide anions at concentrations that may cause either apoptosis or necrosis. We studied membrane organization, dehydrogenase mitochondrial activity and nuclear morphology and integrity, to determine the nature of the death process initiated by superoxide anions and tried to counteract ROS effects with alpha-tocopherol. We found that oxidative stress caused synoviocytes to undergo a process of cell death of an apoptotic nature rather than necrotic. Mitochondrial injury occurred at an early stage, and the FITC-annexin-V-positive/propidium iodide-positive cells occurred later than the metabolic changes. DNA strand breaks were evident at 8 h and nuclear condensation at 24 h. No LDH activity was detected in culture supernatants. In our experimental conditions, alpha-tocopherol had little effect on stress damage; the antioxidant properties of this molecule did not affect the apoptosis caused by superoxide anions.     

Oxidative stress in myotonic dystrophy type 1

Myotonic dystrophy type 1 (DM1) is the most common form of muscular dystrophy affecting adults. The genetic basis of DM1 consists of a mutational expansion of a repetitive trinucleotide sequence (CTG). The number of triplets expansion divides patients in four categories related to the molecular changes (E1, E2, E3, E4). The pathogenic mechanisms of multi-systemic involvement of DM1 are still unclear. DM1 has been suspected to be due to premature aging, that is known to be sustained by increased free radicals levels and/or decreased antioxidants activities in neurodegenerative disorders. Recently, the gain-of-function at RNA level hypothesis has gained great attention, but oxidative stress might act in the disease progression. We have investigated 36 DM1 patients belonging to 22 unrelated families, 10 patients with other myotonic disorders (OMD) and 22 age-matched healthy controls from the clinical, biochemical and molecular point of view. Biochemical analysis detected blood levels of superoxide dismutase (SOD), malonilaldehyde (MDA), vitamin E (Vit E), hydroxyl radicals (OH) and total antioxidant system (TAS). Results revealed that DM1 patients showed significantly higher levels of SOD (+40%; MAL (+57%; RAD 2 (+106%; and TAS (+20%; than normal controls. Our data support the hypothesis of a pathogenic role of oxidative stress in DM1 and therefore confirm the detrimental role played by free radicals in this pathology and suggest the opportunity to undertake clinical trials with antioxidants in this disorder.     

Stress Resistance of Drosophila Transgenic for Bovine CuZn Superoxide Dismutase

Several oxidative and non-oxidative stresses were applied to two transgenic strains of Drosophila melanogaster (designated P(bSOD)5 and P(bSOD)11) that express superoxide dismutase (SOD) at elevated levels, and control strains that express normal SOD levels. Transgenic strain P(bSOD)5 exposed to paraquat (1,1'-dimethyl-4,4'-bipyridinium dichloride), a redox cycling agent that generates superoxide anion when metabolized in vivo, was significantly more resistant to this xenobiotic than control flies. When test flies were subjected to 100% oxygen for 20 min each day, the mean lifespan was 3.62 days for control strain 25, but 4.35 days for both transgenic strains. The mortality curves of all strains fed 1% H₂O₂ were similar, but the median lifespan of 72 h for controls and 64 h for transgenics suggests that the transgenic flies were slightly more sensitive to H₂O₂. The activity of catalase was the same for all strains. Using starvation resistance as a non-oxidative stress, flies maintained on water without any food had identical survival curves; for all strains, the median lifespan was 72 h. Throughout the lifespan, no statistically significant difference in physical activity was displayed for transgenic versus control flies. Collectively, these data suggest that the increased lifespan previously observed in SOD transgenics is specifically related to resistance to oxidative stresses.     

Reactive oxygen species, mitochondria, apoptosis and aging

In this paper, we shall review various antioxygen defense systems of the cell paying particular attention to those that prevent superoxide formation rather than scavenge already formed superoxide and its products. The role of uncoupled, decoupled and non-coupled respiration, mitochondrial pore, mitochondrion-linked apoptosis will be considered. Mitochondrial theory of aging will be regarded in context of reactive oxygen species-induced damage of mitochondrial DNA. (Mol Cell Biochem 174: 305–319, 1997)     

Mitochondrial metabolism of reactive oxygen species

Oxidative stress is considered a major contributor to etiology of both normal senescence and severe pathologies with serious public health implications. Mitochondria generate reactive oxygen species (ROS) that are thought to augment intracellular oxidative stress. Mitochondria possess at least nine known sites that are capable of generating superoxide anion, a progenitor ROS. Mitochondria also possess numerous ROS defense systems that are much less studied. Studies of the last three decades shed light on many important mechanistic details of mitochondrial ROS production, but the bigger picture remains obscure. This review summarizes the current knowledge about major components involved in mitochondrial ROS metabolism and factors that regulate ROS generation and removal. An integrative, systemic approach is applied to analysis of mitochondrial ROS metabolism, which is now dissected into mitochondrial ROS production, mitochondrial ROS removal, and mitochondrial ROS emission. It is suggested that mitochondria augment intracellular oxidative stress due primarily to failure of their ROS removal systems, whereas the role of mitochondrial ROS emission is yet to be determined and a net increase in mitochondrial ROS production in situ remains to be demonstrated.Translated from Biokhimiya, Vol. 70, No. 2, 2005, pp. 246–264.Original Russian Text Copyright © 2005 by Andreyev, Kushnareva, Starkov.This revised version was published online in April 2005 with corrections to the post codes.     

Catalase and Superoxide Dismutase: Distribution, Properties, and Physiological Role in Cells of Strict Anaerobes

This review considers the distribution of the main enzymes of antioxidative defense, superoxide dismutase (SOD) and catalase, in various groups of strictly anaerobic microorganisms: bacteria of the genus Clostridium, Bacteroides, sulfate-reducing and acetogenic bacteria, methanogenic archaea, etc. Molecular and biochemical properties of purified Fe-containing SODs, cambialistic SODs, and heme catalases are presented. The physiological role and origin of the enzymes of antioxidative defense in strict anaerobes are discussed. Physiological responses (induction of SOD and catalase) to factors provoking oxidative stress in the cells of strict anaerobes able to maintain viability under aerobic conditions are also considered.     

Superoxide dismutase,catalase, and U78517F attenuate neuronal damage in gerbils with repeated brief ischemic insults

Repeated ischemic insults at one hour intervals result in more severe neuronal damage than a single similar duration insult. The mechanism for the more severe damage with repetitive ischemia is not fully understood. We hypothesized that the prolonged reperfusion periods between the relatively short ischemic insults may result in a pronounced generation of oxygen free radicals (OFRs). In this study, we tested the protective effects of superoxide dismutase (SOD) and catalase (alone or in combination), and U78517F in a gerbil model of repetitive ischemia. Three episodes (two min each) of bilateral carotid occlusion were used at one hour intervals to produce repetitive ischemia. Superoxide dismutase and catalase were infused via osmotic pumps into the lateral ventricles. Two doses of U78517F were given three times per animal, one half hour prior to each occlusion. Neuronal damage was assessed 7 days later in several brain regions using the silver staining technique. The Mann-Whitney U test was used for statistical comparison. Superoxide dismutase showed significant protection in the hippocampus (CA4), striatum, thalamus and the medial geniculate nucleus (MGN). Catalase showed significant protection in the striatum, hippocampus, thalamus, and MGN and the substantia nigra reticulata. Combination of the two resulted in additional protection in the cerebral cortex. Compared to the controls, there was little protection with a dose of 3 mg/kg of U78517F. There was significant protection with a dose of 10 mg/kg in the hippocampus (CA4), striatum, thalamus, medial geniculate nucleus and the substantia nigra reticulata. The significant protection noted with SOD, catalase or U78517F with repeated ischemia supports, the hypothesis that OFRs may play a role in neuronal damage in repeated cerebral ischemia.     

Scavenging of reactive oxygen species and prevention of oxidative neuronal cell damage by a novel gallotannin,pistafolia A

Pistafolia A is a novel gallotannin isolated from the leaf extract of Pistacia weinmannifolia. In the present investigation, the ability of Pistafolia A to scavenge reactive oxygen species including hydroxyl radicals and superoxide anion was measured by ESR spin trapping technique. The inhibition effect on iron-induced lipid peroxidaiton in liposomes was studied. The protective effects of Pistafolia A against oxidative neuronal cell damage and apoptosis induced by peroxynitrite were also assessed. The results showed that Pistafolia A could scavenge both hydroxyl radicals and superoxide anion dose-dependently and inhibit lipid peroxidation effectively. In cerebellar granule cells pretreated with Pistafolia A, peroxynitrite-induced oxidative neuronal damage and apoptosis were prevented markedly. The antioxidant capacity of Pistafolia A was much more potent then that of the water-soluble analog of vitamin E, Trolox. The results suggested that Pistafolia A might be used as an effective natural antioxidant for the prevention and cure of neuronal diseases associated with the production of peroxynitrite and related reactive oxygen species.     

Protection against oxygen radicals: an important defence mechanism studied in transgenic plants

Free radicals and other active derivatives of oxygen are inevitable by-products of biological redox reactions. Reduced oxygen species, such as hydrogen peroxide, the superoxide radical anion and hydroxyl radicals, inactivate enzymes and damage important cellular components. In addition, singlet oxygen, produced via formation of triplet state chlorophyll, is highly destructive. This oxygen species initiates lipid peroxidation, and produces lipid peroxy radicals and lipid hydroperoxides that are also very reactive. The increased production of toxic oxygen derivatives is considered to be a universal or common feature of stress conditions. Plants and other organisms have evolved a wide range of mechanisms to contend with this problem. The antioxidant defence system of the plant comprises a variety of antioxidant molecules and enzymes. Considerable interest has been focused on the ascorbate-glutathione cycle because it has a central role in protecting the chloroplasts and other cellular compartments from oxidative damage. It is clear that the capacity and activity of the antioxidative defence systems are important in limiting photo-oxidative damage and in destroying active oxygen species that are produced in excess of those normally required for signal transduction or metabolism. In our studies on this system, we became aware that the answers to many unresolved questions concerning the nature and regulation of the antioxidative defence system could not be obtained easily by either a purely physiological or purely biochemical approach. Transgenic plants offered us a means by which to achieve a more complete understanding of the roles of the enzymes involved in protection against stress of many types: environmental and man-made. The ability to engineer plants which express introduced genes at high levels provides an opportunity to manipulate the levels of these enzymes, and hence metabolism in vivo. Studies on transformed plants expressing increased activities of single enzymes of the antioxidative defence system indicate that it is possible to confer a degree of tolerence to stress by this means. However, attempts to increase stress resistance by simply increasing the activity of one of the antioxidant enzymes have not always been successful presumably because of the need for a balanced interaction of protective enzymes. The study of these transformed plants has allowed a more complete understanding of the roles of individual enzymes in metabolism. Protection against oxidative stress has become a feasible objective through the application of molecular genetic techniques in conjunction with a biochemical and physiological approach.     

Curcumin inhibits apoptosis by regulating intracellular calcium release,reactive oxygen species and mitochondrial depolarization levels in SH-SY5Y neuronal cells

Neurological diseases such as Alzheimer’s and Parkinson’s diseases are incurable progressive neurological disorders caused by the degeneration of neuronal cells and characterized by motor and non-motor symptoms. Curcumin, a turmeric product, is an anti-inflammatory agent and an effective reactive oxygen and nitrogen species scavenging molecule. Hydrogen peroxide (H₂O₂) is the main source of oxidative stress, which is claimed to be the major source of neurological disorders. Hence, in this study we aimed to investigate the effect of curcumin on Ca²⁺ signaling, oxidative stress parameters, mitochondrial depolarization levels and caspase-3 and -9 activities that are induced by the H₂O₂ model of oxidative stress in SH-SY5Y neuronal cells. SH-SY5Y neuronal cells were divided into four groups namely, the control, curcumin, H₂O₂, and curcumin?+?H₂O₂ groups. The dose and duration of curcumin and H₂O₂ were determined from published data. The cells in the curcumin, H₂O₂, and curcumin?+?H₂O₂ groups were incubated for 24?h with 5?µM curcumin and 100?µM H₂O₂. Lipid peroxidation and cytosolic free Ca²⁺ concentrations were higher in the H₂O₂ group than in the control group; however, their levels were lower in the curcumin and curcumin?+?H₂O₂ groups than in the H₂O₂ group alone. Reduced glutathione (GSH) and glutathione peroxidase (GSH-Px) values were lower in the H₂O₂ group although they were higher in the curcumin and curcumin?+?H₂O₂ groups than in the H₂O₂ group. Caspase-3 activity was lower in the curcumin group than in the H₂O₂ group. In conclusion, curcumin strongly induced modulator effects on oxidative stress, intracellular Ca²⁺ levels, and the caspase-3 and -9 values in an experimental oxidative stress model in SH-SY5Y cells.     

Reactive oxygen species as mediators of sperm capacitation and pathological damage

Oxidative stress plays a major role in the life and death of mammalian spermatozoa. These gametes are professional generators of reactive oxygen species (ROS), which appear to derive from three potential sources: sperm mitochondria, cytosolic L‐amino acid oxidases, and plasma membrane Nicotinamide adenine dinucleotide phosphate oxidases. The oxidative stress created via these sources appears to play a significant role in driving the physiological changes associated with sperm capacitation through the stimulation of a cyclic adenosine monophosphate/Protein kinase A phosphorylation cascade, including the activation of Extracellular signal regulated kinase‐like proteins, massive up‐regulation of tyrosine phosphorylation in the sperm tail, as well as the induction of sterol oxidation. When generated in excess, however, ROS can induce lipid peroxidation that, in turn, disrupts membrane characteristics that are critical for the maintenance of sperm function, including the capacity to fertilize an egg. Furthermore, the lipid aldehydes generated as a consequence of lipid peroxidation bind to proteins in the mitochondrial electron transport chain, triggering yet more ROS generation in a self‐perpetuating cycle. The high levels of oxidative stress created as a result of this process ultimately damage the DNA in the sperm nucleus; indeed, DNA damage in the male germ line appears to be predominantly induced oxidatively, reflecting the vulnerability of these cells to such stress. Extensive evaluation of antioxidants that protect the spermatozoa against oxidative stress while permitting the normal reduction‐oxidation regulation of sperm capacitation is therefore currently being undertaken, and has already proven efficacious in animal models.     

Salt-induced oxidative stress mediated by activated oxygen species in pea leaf mitochondria

The effect in vivo of salt stress on the activated oxygen metabolism of mitochondria, was studied in leaves from two NaCl-treated cultivars of Pisum sativum L. with different sensitivity to NaCl. In mitochondria from NaCl-sensitive plants, salinity brought about a significant decrease of Mn-SOD (EC 1. 15. 1. 1) Cu, Zn-SOD I (EC 1. 15. 1. 1) and fumarase (EC 4. 2. 1. 2) activities. Conversely, in salt-tolerant plants NaCl treatment produced an increase in the mitochondrial Mn-SOD activity and, to a lesser extent, in fumarase activity. In mitochondria from both salt-treated cultivars, the internal H₂O₂ concentration remained unchanged. The NADH- and succinate-dependent generation of O₂^.−radicals by submitochondrial particles and the lipid peroxidation of mitochondrial membranes, increased as a result of salt treatment, and these changes were higher in NaCl-sensitive than in NaCl-tolerant plants. Accordingly, the enhanced rates of superoxide production by mitochondria from salt-sensitive plants were concomitant with a strong decrease in the mitochondrial Mn-SOD activity, whereas NaCl-tolerant plants appear to have a protection mechanism against salt-induced increased O₂^.− production by means of the induction of the mitochondrial Mn-SOD activity. These results indicate that in the subcellular toxicity of NaCl in pea plants, at the level of mitochondria, an oxidative stress mechanism mediated by superoxide radicals is involved, and also imply a function for mitochondrial Mn-SOD in the molecular mechanisms of plant tolerance to NaCl.     

Comparative Analysis of Superoxide Dismutase Activity between Acute Pharmacological Models and a Transgenic Mouse Model of Huntington's Disease

We examined the activity of striatal superoxide dismutase (SOD) in two acute pharmacological models of Huntington's disease (HD), and compared it with SOD activity in the striata of mice transgenic for the HD mutation. Total SOD, and Cu/ZnSOD activities increased in young transgenic mice, but decreased in older (35 week) mice. We consider that the increased enzyme activity represents a compensatory mechanism to protect cells from free radical-induced damage, but the system becomes insufficient in older animals. Major decreases in SOD activity were also observed both after quinolinic acid and 3-nitropropionic acid intrastriatal injections. The present results indicate that in both types of HD models striatal oxidative damage occurs, and that it is associated with alterations in the cellular antioxidant system.     

The free-radical damage theory: Accumulating evidence against a simple link of oxidative stress to ageing and lifespan

Recent work on a small European cave salamander (Proteus anguinus) has revealed that it has exceptional longevity, yet it appears to have unexceptional defences against oxidative damage. This paper comes at the end of a string of other studies that are calling into question the free-radical damage theory of ageing. This theory rose to prominence in the 1990s as the dominant theory for why we age and die. Despite substantial correlative evidence to support it, studies in the last five years have raised doubts over its importance. In particular, these include studies of mice with the major antioxidant genes knocked out (both singly and in combination), which show the expected elevation in oxidative damage but no impact on lifespan. Combined, these findings raise fundamental questions over whether the free-radical damage theory remains useful for understanding the ageing process, and variation in lifespan and life histories.     

Induction of heat tolerance in wheat coleoptiles by calcium ions and its relation to oxidative stress

Effects of Ca²⁺ ions on the intensity of lipid peroxidation, activities of guaiacol peroxidase, superoxide dismutase (SOD), and catalase, as well as on heat resistance of winter wheat (Triticum aestivium L.) coleoptiles were examined. A preliminary incubation of coleoptile segments in a 5 mM CaCl₂ solution was shown to improve their survival rates after an injuring heat treatment (43.5°C). The effect of Ca²⁺ was suppressed by the inhibitor of Ca²⁺ channels (1 mM LaCl₃). An incubation of coleoptiles in the presence of 5 mM CaCl₂ prior to the stress treatment elevated the content of lipid peroxidation product, malondialdehyde (MDA) and stimulated the activities of guaiacol peroxidase, SOD, and catalase. After the heat exposure of untreated and Ca²⁺-treated seedlings, differential changes in MDA content and in activities of guaiacol peroxidase, SOD, and catalase were observed. It is concluded that a short-term oxidative stress arising in Ca²⁺-enriched plant tissues after the heat treatment is unrelated to their irreversible damage.Translated from Fiziologiya Rastenii, Vol. 52, No. 2, 2005, pp. 227–232.Original Russian Text Copyright © 2005 by Kolupaev, Akinina, Mokrousov.This revised version was published online in April 2005 with a corrected cover date.     

Water stress-induced oxidative damage and antioxidant responses in micropropagated banana plantlets

Oxidative injury and antioxidant responses were investigated in two banana genotypes (Musa AAA Berangan and Musa AA Mas) subjected to 40 % PEG-induced water stress. PEG treatment resulted in oxidative injury, as expressed in increased lipid peroxidation and reduced membrane stability index, in both cultivars; however, greater oxidative injury was detected in Mas. Under PEG treatment, catalase activity and glutathione reductase activity were enhanced in both cultivars, but were higher in Mas. Ascorbate peroxidase activity was enhanced in Berangan under water stress, but was unaffected in Mas. Meanwhile, superoxide dismutase activity was inhibited in both cultivars under water stress, but higher activity was detected in Berangan. Higher ascorbate peroxidase and superoxide dismutase activities were associated with greater protection against water stress-induced oxidative injury.     

Iron accumulation, iron-mediated toxicity and altered levels of ferritin and transferrin receptor in cultured astrocytes during incubation with ferric ammonium citrate

The cellular uptake and storage of iron have to be tightly regulated in order to provide iron for essential cellular functions while preventing the iron-catalysed generation of reactive oxygen species (ROS). In contrast to cells in other organs, little is known about the regulation of iron metabolism in brain cells, particularly in astrocytes. To investigate the regulation of iron metabolism in astrocytes we have used primary astrocyte cultures from the brains of newborn rats. After application of ferric ammonium citrate (FAC), cultured astrocytes accumulated iron in a time- (0-48 h) and concentration-dependent (0.01-1 mm) manner. This accumulation was prevented if FAC was applied in combination with the iron-chelator deferoxamine (DFX). Application of FAC to astrocyte cultures caused a strong increase in the cellular content of the iron storage protein ferritin and a decrease in the amount of transferrin receptor (TfR), which is involved in the transferrin-mediated uptake of iron into cells. In contrast, application of DFX strongly increased the level of TfR. Both up-regulation of ferritin content by iron application and up-regulation of TfR content by DFX were prevented by the protein synthesis inhibitor cycloheximide (CHX). During incubation of astrocytes with FAC, a mild and transient increase in the extracellular activity of the cytosolic enzyme lactate dehydrogenase and in the concentration of intracellular ROS was observed. In contrast, prevention of protein synthesis by CHX during incubation with FAC resulted in significantly more cell loss and a persistent and intense increase in the production of intracellular ROS. These results demonstrate that both iron accumulation and deprivation modulate the synthesis of ferritin and TfR in astrocytes and that protein synthesis is required to prevent iron-mediated toxicity in astrocytes.     

Chilling-enhanced photooxidation: The production,action and study of reactive oxygen species produced during chilling in the light

Chilling-enhanced photooxidation is the light- and oxygen-dependent bleaching of photosynthetic pigments that occurs upon the exposure of chilling-sensitive plants to temperatures below approximately 10 °C. The oxidants responsible for the bleaching are the reactive oxygen species (ROS) singlet oxygen (¹O₂), superoxide anion radical (O ₂ ,hydrogen peroxide (H₂O₂), the hydroxyl radical (OH·), and the monodehydroascorbate radical (MDA) which are generated by a leakage of absorbed light energy from the photosynthetic electron transport chain. Cold temperatures slow the energy-consuming Calvin-Benson Cycle enzymes more than the energy-transducing light reactions, thus causing leakage of energy to oxygen. ROS and MDA are removed, in part, by the action of antioxidant enzymes of the Halliwell/Foyer/Asada Cycle. Chloroplasts also contain high levels of both lipid- and water-soluble antioxidants that act alone or in concert with the HFA Cycle enzymes to scavenge ROS. The ability of chilling-resistant plants to maintain active HFA Cycle enzymes and adequate levels of antioxidants in the cold and light contributes to their ability to resist chilling-enhanced photooxidation. The absence of this ability in chilling-sensitive species makes them susceptible to chilling-enhanced photooxidation. Chloroplasts may reduce the generation of ROS by dissipating the absorbed energy through a number of quenching mechanisms involving zeaxanthin formation, state changes and the increased usage of reducing equivalents by other anabolic pathways found in the stroma. During chilling in the light, ROS produced in chilling-sensitive plants lower the redox potential of the chloroplast stroma to such a degree that reductively-activated regulatory enzymes of the Calvin Cycle, sedohepulose 1,7 bisphosphatase (EC 3.1.3.37) and fructose 1,6 bisphosphatase (EC 3.1.3.11), are oxidatively inhibited. This inhibition is reversible in vitro with a DTT treatment indicating that the enzymes themselves are not permanently damaged. The inhibition of SBPase and FBPase may fully explain the inhibition in whole leaf gas exchange seen upon the rewarming of chilling-sensitive plants chilled in the light. Methods for the study of ROS in chilling-enhanced photooxidation and challenges for the future are discussed.Abbreviations ASP ascorbate-specific peroxidase - -TH reduced -tocopherol - DTT dithiothreitol - FBP fructose 1,6 bisphosphate - FBPase fructose 1,6 bisphosphatase (EC 3.1.3.11) - HFA Cycle the Halliwell/Foyer/Asada Cycle responsible for the enzymatic removal of ROS in the chloroplast stroma - MDA monodehydroascorbate radical - MDAR monodehydroascorbate reductase - ROS reactive oxygen species - SBP sedohepulose 1,7 bisphosphate - SBPase sedohepulose 1,7 bisphosphatase (EC 3.1.3.37) - SOD superoxide dismutase