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1.
马旭俊  朱大海 《遗传》2003,25(2):225-231
超氧化物歧化酶(superoxide dismutase,SOD)在需氧原核生物和真核生物中广泛存在,是活性氧清除系统中第一个发挥作用的抗氧化酶。植物正常代谢过程和在各种环境胁迫下均能产生活性氧和自由基,活性氧和自由基的积累引起细胞结构和功能的破坏。SOD岐化超氧物阴离子自由基生成过氧化氢和分子氧,在保护细胞免受氧化损伤过程中具有十分重要的作用。本文综述了SOD的功能、在细胞中的分布、表达调控和与植物抗逆性的关系。 Abstract:Superoxide Dismutases (SODs) are ubiquitously expressed antioxidant enzyme in aerobic organisms and catalyze dismutation of superoxide anion to hydrogen and molecular oxygen,the first step in active oxygen-scavenging systems.SODs play a central role in protecting cells against the toxic effects of reactive oxygen species generated during normal cellular metabolic activity or as a result of various environmental stresses.This paper reviews the expression and regulation of Sod genes and their functional role(s) during development and in response to stresses.  相似文献
2.
活性氧清除系统对干旱胁迫的响应机制   总被引:81,自引:8,他引:73  
干旱胁迫是影响植物生长发育的主要因子,干旱引起活性氧自由基增加,使植物细胞遭受氧化胁迫.植物体通过酶促和非酶促两大保护系统清除活性氧,活性氧自由基的变化也会引起抗氧化防御系统的不同变化.同时干旱胁迫下活性氧的产生也与ABA的积累、脯氨酸的积累以及叶绿素荧光猝灭密切相关,因此了解活性氧清除系统对干旱胁迫的响应机制以及活性氧在植物生理生化过程中的作用是非常必要的。  相似文献
3.
The need for methods to identify disease biomarkers is underscored by the survival-rate of patients diagnosed at early stages of cancer progression. Surface enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) is a novel approach to biomarker discovery that combines two powerful techniques: chromatography and mass spectrometry. One of the key features of SELDI-TOF MS is its ability to provide a rapid protein expression profile from a variety of biological and clinical samples. It has been used for biomarker identification as well as the study of protein-protein, and protein-DNA interaction. The versatility of SELDI-TOF MS has allowed its use in projects ranging from the identification of potential diagnostic markers for prostate, bladder, breast, and ovarian cancers and Alzheimer's disease, to the study of biomolecular interactions and the characterization of posttranslational modifications. In this minireview we discuss the application of SELDI-TOF MS to protein biomarker discovery and profiling.  相似文献
4.
Antioxidants, Oxidative Damage and Oxygen Deprivation Stress: a Review   总被引:56,自引:1,他引:55  
Oxidative stress is induced by a wide range of environmentalfactors including UV stress, pathogen invasion (hypersensitivereaction), herbicide action and oxygen shortage. Oxygen deprivationstress in plant cells is distinguished by three physiologicallydifferent states: transient hypoxia, anoxia and reoxygenation.Generation of reactive oxygen species (ROS) is characteristicfor hypoxia and especially for reoxygenation. Of the ROS, hydrogenperoxide (H2O2) and superoxide (O2·–) are bothproduced in a number of cellular reactions, including the iron-catalysedFenton reaction, and by various enzymes such as lipoxygenases,peroxidases, NADPH oxidase and xanthine oxidase. The main cellularcomponents susceptible to damage by free radicals are lipids(peroxidation of unsaturated fatty acids in membranes), proteins(denaturation), carbohydrates and nucleic acids. Consequencesof hypoxia-induced oxidative stress depend on tissue and/orspecies (i.e. their tolerance to anoxia), on membrane properties,on endogenous antioxidant content and on the ability to inducethe response in the antioxidant system. Effective utilizationof energy resources (starch, sugars) and the switch to anaerobicmetabolism and the preservation of the redox status of the cellare vital for survival. The formation of ROS is prevented byan antioxidant system: low molecular mass antioxidants (ascorbicacid, glutathione, tocopherols), enzymes regenerating the reducedforms of antioxidants, and ROS-interacting enzymes such as SOD,peroxidases and catalases. In plant tissues many phenolic compounds(in addition to tocopherols) are potential antioxidants: flavonoids,tannins and lignin precursors may work as ROS-scavenging compounds.Antioxidants act as a cooperative network, employing a seriesof redox reactions. Interactions between ascorbic acid and glutathione,and ascorbic acid and phenolic compounds are well known. Underoxygen deprivation stress some contradictory results on theantioxidant status have been obtained. Experiments on overexpressionof antioxidant production do not always result in the enhancementof the antioxidative defence, and hence increased antioxidativecapacity does not always correlate positively with the degreeof protection. Here we present a consideration of factors whichpossibly affect the effectiveness of antioxidant protectionunder oxygen deprivation as well as under other environmentalstresses. Such aspects as compartmentalization of ROS formationand antioxidant localization, synthesis and transport of antioxidants,the ability to induce the antioxidant defense and cooperation(and/or compensation) between different antioxidant systemsare the determinants of the competence of the antioxidant system.  相似文献
5.
线粒体,活性氧和细胞凋亡   总被引:55,自引:1,他引:54       下载免费PDF全文
在能量代谢和自由基代谢中,线粒体均占据着十分重要的地位.通过呼吸链电子漏途径,线粒体产生大量超氧阴离子,并通过链式反应形成对机体有损伤作用的活性氧.通过呼吸链电子漏,氧化磷酸化解偶联,线粒体内膜产生通透性转变孔道(PTP)及Box-和/或PTP-介导的细胞色素c向胞质的转移等种种因素,线粒体参与一般抗氧化防御及细胞凋亡等重要生理过程的调控.在与线粒体相关的细胞凋亡中,活性氧的信号作用是十分明显的.  相似文献
6.
采用15%的聚乙二醇-6000(PEG-6000)对扬麦158三叶一心期的幼苗根部进行轻度渗透胁迫处理,并通过添加不同浓度的一氧化氮(nitric oxide,NO)供体硝普钠(sodium nitropussidi,SNP)和相应的对照(BO-3/NO-2),研究外源NO处理对渗透胁迫下小麦幼苗叶片膜脂过氧化作用的影响.结果发现,0.1 nnol/L的SNP能降低渗透胁迫造成的小麦幼苗叶片脂氧合酶(lipoxygenase,LOX)活性的提高,降低超氧阴离子(O-2)的产生速率和质膜相对透性的增加以及丙二醛(MDA)和H2O2的累积;0.1 mmol/L的SNP还能够诱导超氧化物歧化酶(superoxide dismutase,SOD)活性,加速脯氨酸(Pro)的累积,而0.5mmo1/L的SNP和0.1mmo1/L的NO3/NO2(对照)处理的效果则不明显.上述结果表明低浓度NO对渗透胁迫造成的膜脂过氧化有明显的缓解效应.  相似文献
7.
Antimicrobial properties of tannins   总被引:50,自引:0,他引:50  
Tannin toxicity for fungi, bacteria and yeasts is reviewed and compared to toxicity of related lower molecular weight phenols. The dependence of toxicity on tannin structure is examined. The different mechanisms proposed so far to explain tannin antimicrobial activity include inhibition of extracellular microbial enzymes, deprivation of the substrates required for microbial growth or direct action on microbial metabolism through inhibition of oxidative phosphorylation. A further mechanism involving iron deprivation is proposed. Many microorganisms can overcome plant defences based on tannins. They may detoxify tannins through synthesis of tannin- complexing polymers, oxidation, tannin biodegradation or synthesis of siderophores.  相似文献
8.
J. M. Oades 《Plant and Soil》1984,76(1-3):319-337
Summary The stability of pores and particles is essential for optimum growth of plants. Two categories of aggregates macro- (> 250 m) and micro- (<250 m) depend on organic matter for stability against disruptive forces caused by rapid wetting. Dispersion of clay particles from microaggregates is promoted by adsorption of complexing organic acids which increase the negative charge on clays. The acids are produced by plants, bacteria and fungi. However, the dispersibility of clay in microaggregates is offset by the binding action of polysaccharides, mainly mucilages produced by bacteria, but also by plant roots and fungal hyphae. The stability of microaggregates is also enhanced by multivalent cations which act as bridges between organic colloids and clays. Macroaggregates are enmeshed by plant roots, both living and decomposing, and are thus sensitive to management, and increase in number when grasses are grown and the soil is not disturbed. Lack of root growth,i.e. fallow, has the opposite effect. Various implications for management of soil structure are discussed.Introductory lecture  相似文献
9.
一氧化氮对盐胁迫下小麦幼苗根生长和氧化损伤的影响   总被引:45,自引:2,他引:43  
0.05和0.10 mmol/L一氧化氮(NO)供体硝普钠(sodium mtropmsside,SNP)处理明显减轻NaCl浓度为150 mmo1/L左右的盐胁迫对小麦幼苗根生长的抑制效应,其中0.05mmol/L的SNP效果最明显;0.30mmol/L以上的SNP处理对根抑制无明显缓解作用;当NaCl浓度大于300 mmol/L时,各种浓度的SNP均不能减轻盐胁迫对根生长的抑制.以N O清除剂血红蛋白(hemoglobin,Hb)以及NOx-,K3Fe(CN)6等为对照,观察到0.05 mmol/L的SNP能不同程度地提高150mmo/L盐胁迫下小麦幼苗根尖细胞中超氧化物歧化酶(SOD)、过氧化物酶(POD)和抗坏血酸过氧化物酶(ascorbateperoxidase,APX)活性,明显降低MDA、H2O2和O2-.的积累,阻断盐胁迫诱导的根尖细胞DNA片段化,表明NO能有效缓解盐胁迫引起的小麦幼苗根尖细胞的氧化损伤.  相似文献
10.
Heme oxygenase-1 (HO-1, HSP32) is an early gene that is responsive to an array of pathological conditions including, but not limited to, hypoxia and cerebral ischemia. HO-1 cleaves the heme molecule and produces carbon monoxide (CO) and biliverdin (an antioxidant) and is essential for iron homeostasis. The purpose of this study was to investigate, using transgenic (Tg) mice, whether overexpression of HO-1 in the brain augments or attenuates cellular injury caused by ischemic stroke. Homozygous HO-1 Tg mice that overexpress HO-1 under the control of the neuron-specific enolase promoter (characterized previously) were used. Under halothane anesthesia and normothermic conditions, wild-type nontransgenic (nTg; n = 22) and HO-1 Tg (n = 24) mice were subjected to middle cerebral artery occlusion (MCAo). Six hours after induction of ischemia, Tg and nTg mice developed infarcts that were 39 +/- 6 and 63 +/- 9 mm3, respectively (p < 0.01). No significant difference between the two strains was observed in the values of brain edema (11.3 +/- 4% in Tg vs. 14.6 +/- 5% in nTg; p < 0.1). At 24 h after MCAo, Tg mice exhibited significant neuroprotection as determined by the stroke volumes (41 +/- 2 mm3 in Tg vs. 74 +/- 5 mm3 in nTg; p < 0.01) and values of ischemic cerebral edema (21 +/- 6% in Tg vs. 35 +/- 11% in nTg; p < 0.01). Data suggest that neuroprotection in Tg mice was, at least in part, related to the following findings: (a) constitutively up-regulated cyclic GMP and bcl-2 levels in neurons; (b) inhibition of nuclear localization of p53 protein; and (c) antioxidant action of HO-1, as detected by postischemic neuronal expression of ferritin, and decreases in iron staining and tissue lipid peroxidation. We suggest that pharmacological stimulation of HO-1 activity may constitute a novel therapeutic approach in the amelioration of ischemic injury during the acute period of stroke.  相似文献
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