渗透胁迫对水稻幼苗膜脂过氧化及体内保护系统的影响

两个不同抗旱性的水稻品种对PEG6000渗透胁迫(-0.5MPa,-0.8MPa)的反应具有一定差异。渗透胁迫下SOD,POD和CAT活性及Vc,Car含量与膜脂过氧化水平及膜透性呈一定负相关性,表明这些指标可作为水稻抗旱育种的参考依据。     

不同抗旱性玉米幼苗根系抗氧化系统对水分胁迫的反应

以抗旱性不同的2个玉米品种为材料,研究不同程度水分胁迫下玉米根系活性氧清除系统的变化及膜脂过氧化水平。明确了轻度水分胁迫下玉米根系POD、CAT、APX等保护酶活性明显提高;中、重度胁迫下其活性急剧下降,但几种酶对水分胁迫的敏感程度不同。SOD对水分胁迫表现最不敏感,在中度水分胁迫下仍保持上升趋势;抗氧化剂GSH含量变化趋势与保护酶相似;而AsA含量在不同程度水分胁迫下持续下降;MDA含量随水分胁迫程度加剧而增加。其中抗旱性强的鲁玉14与抗旱性弱的掖单13相比具有较高的保护酶活性和抗氧化剂含量,膜脂过氧化程度较轻,除POD外,品种间抗氧化酶活性（抗氧化剂含量）呈极显著差异,说明抗氧化能力强是抗旱性品种具有较强抗旱性的重要原因之一。     

干旱胁迫对菜苔叶片保护酶活性和膜脂过氧化的影响

以3个不同耐旱性的菜苔（Brassica parachinensis L.H.Bailey）品种为试材,研究了干旱胁迫对叶片保护酶活性和膜脂过氧化的影响及其与抗旱性的关系。干旱胁迫条件下,菜苔叶片的电解质外渗率和MDA含量呈上升趋势,叶绿素含量、抗坏血酸含量和SOD活性呈下降趋势,CAT活性表现为先上升后下降。耐旱品种比不耐旱品种具有较高的叶绿素含量和抗坏血酸含量,具有较低的电解质外渗率和MDA含量;耐旱品种的SOD活性比不耐旱品种下降幅度小。轻度干旱胁迫下,耐旱品种的CAT活性上升幅度比不耐旱品种高;重度干旱胁迫下耐旱品种的CAT活性下降程度比不耐旱品种低。耐旱品种的POD活性在干旱条件下先上升而后降低,不耐品种的POD活性处于下降趋势。干旱6d后,耐旱品种的SOD、CAT和POD活性显著高于不耐旱品种。     

干旱胁迫下外源水杨酸对黄瓜幼苗膜脂过氧化和光合特性的影响

为了探讨外源水杨酸(SA)提高植物抗旱性的相关机制,研究了干旱胁迫下(基质含水量为饱和持水量的60％和50％),根际施用外源SA对黄瓜幼苗生长、膜脂过氧化、脯氨酸积累、水分利用效率、净光合速率(Pn)和叶绿素荧光参数的影响.结果表明:SA处理能够缓解干旱胁迫对黄瓜幼苗生长、Pn和水分利用效率的抑制,减小膜脂过氧化程度,促进脯氨酸的积累;添加外源SA显著减小了干旱胁迫下黄瓜幼苗的PSⅡ最大光化学效率、PSⅡ实际光化学效率、PSⅡ潜在活性、PSⅡ有效光化学效率和光化学猝灭系数的下降幅度,抑制了非光化学猝灭系数的升高.添加外源SA可以缓解干旱胁迫造成的膜脂过氧化对膜系统的氧化损伤,并通过增强PSⅡ反应中心活性提高了Pn,有助于水分的利用,同时增大渗透调节能力,减少水分的散失,提高水分利用效率,从而增强植株对干旱的适应能力.     

干旱对大豆线粒体膜脂的磷脂和脂肪酸组分的影响

干旱胁迫致使大豆叶片线粒体膜脂的PG摩尔百分含量降低,而LPC,PC,PI,PE,PA则明显提高。抗旱品种和敏感品种之间棕榈酸及亚麻酸含量有明显差异,且抗旱品种叶片线粒体膜脂的总脂肪酸不饱和指数低于敏感品种。     

甘薯苗期离体叶片对水分胁迫的适应能力（简报）

甘薯苗期离体叶片在水分胁迫下的膜脂过氧化水平与抗旱能力呈明显的负相关。6个品种对水分胁迫适应能力由强到弱依次为：渝薯20、南薯88、宁180、徐薯18、农大红、南丰。在水分胁迫条件下,各品种中游离脯氨酸均有不同程度的积累。积累量与品种适应水分胁迫能力的关系不密切。     

NaCl胁迫及外源自由基对离体小麦叶片O_2~和膜脂质过氧化的影响(简报)

在NaCl胁迫初期,离体小麦叶片内O2含量较低,随着胁迫时间的延长,自由基产生速率逐渐增加,第4天达最高峰,以后又迅速下降。随着NaCl胁迫强度增加,叶片内O2浓度升高,膜脂过氧化作用增强,膜透性增加、SOD活性下降。外源自由基处理的叶片中自由基含量增加,O2产生高峰提前,膜脂过氧化作用和膜透性增加。     

短时间和长时间盐度对木榄幼苗生长及叶片膜脂过氧化作用的研究

对短时间和长时间盐胁迫下红树植物木榄 (Bruguieragymnorrhiza(L .)Lamk )幼苗的生长、叶片膜脂过氧化作用、叶绿素含量、电解质渗漏率、叶片肉质化程度等与盐胁迫强度之间的关系进行了对比研究。不同的盐胁迫时间下 ,随盐胁迫强度的提高 ,木榄幼苗的生长、叶片超氧化物歧化酶 (SOD)活性、丙二醛 (MDA)含量、肉质化程度S及叶绿素含量等变化趋势相似 ,表明不同盐胁迫时间下红树植物木榄的耐盐机制并没有发生根本改变。但随着盐胁迫时间的延长 ,木榄幼苗发生了一系列适应盐胁迫的变化 ,如木榄幼苗的最适生长盐度由 10g/L提高到 2 0g/L ,叶片电解质渗漏率下降 ,表明在本研究的实验条件下 ,长时间盐胁迫下木榄幼苗表现出对盐胁迫更大的适应性。膜脂过氧化不是盐胁迫下木榄叶片膜损伤的主要原因     

NO对小麦叶片干旱诱导膜脂过氧化的调节效应

分析了一氧化氮(NO)对小麦(Triticum aestivum L．)叶片干旱诱导膜脂过氧化的影响。结果表明：不同浓度NO均能使干旱胁迫下小麦叶片的相对含水量先降后升,而：MDA含量先升后降,O2-释放速率下降,SOD活性升高,POD活性降低;同时,NO可以提高脯氨酸含量。这些结果表明NO提高了小麦叶片的抗氧化能力,降低了干旱胁迫诱导的膜脂过氧化损伤。     

干旱及活性氧引起小麦膜脂过氧化与脱酯化

水分胁迫下随小麦叶片含水量下降,膜透性增大,两者高度负相关;同时叶片H₂O₂含量和叶片微粒体膜脂过氧化水平都上升,无论在干旱时或在外源O₂^-和·OH作用时,微粒体膜流动性均下降,外源O₂^-和·OH处理微粒体膜后,膜脂过氧化水平明显增高,脂肪酸不饱和度明显下降;同时磷脂减少,游离脂肪酸增加。结果表明干旱可能使植物体内活性氧增多,从而导致膜损伤,这种由活性氧引起的膜损伤是膜脂过氧化和脱酯化共同作用的结果     

脂质过氧化对人红细胞膜脂流动性的影响

研究枯稀过氧化氢/高铁血红素体系所产生的烷基过氧自由基对红细胞的损伤。测定了脂质过氧化的产物——丙二脂的生成,并证明阿魏酸钠对脂质过氧化的抑制。荧光偏振的结果指出,膜脂过氧化以后降低了膜脂的流动性。人红细胞用5DSA和16DSA标记并用ESR检测膜脂流动性,结果表明,序参数S几乎没有发生变化,旋转相关时间τ值的增加证明膜脂过氧化以后,疏水尾部的物理状态发生了改变。经脂质过氧化以后,红细胞膜中的不饱和脂防酸的减少,可能是降低膜脂流动性的原因之一。     

克山病病区粮喂养大鼠红细胞膜脂流动性的变化

本文观察了低硒的克山病病区粮和克山病病区粮补硒后喂养大鼠对其红细胞膜脂流动性的影响。实验结果表明克山病病区粮喂养的大鼠红细胞膜脂流动性较正常对照降低,其原因可能与机体处于低硒状态下红细胞膜结合硒含量降低、红细胞膜胆固醇含量及脂质过氧化产物升高有关,克山病病区粮补硒后喂养大鼠,其红细胞膜脂流动性恢复至正常对照。     

小麦原生质体分离过程中生理状态的变化

酶解处理使小麦对肉原生质体膜流动性降低,膜脂过氧化产物丙二醛（ＭＤＡ）积累,说明脱璧过程对细胞有伤害作用,损伤位点可能发生在膜上。胚性愈伤组织的具有分裂能力的原生质体,不表现上述变化。酶解脱壁还使超氧化物歧化酶（ＳＯＤ）和过氧化氢酶（ＣＡＴ）活性上升;过氧化物酶（ＰＯＸ）在叶肉原生质体中活性下降,在胚性愈伤组织来源的原生质体中活性上升。以上结果表明：在原生质体分离过程中,细胞的生理特性发生了变化;膜损伤的发生可能与原生质体能否进入正常分裂状态有关。     

多不饱和脂肪酸对细胞膜功能影响的研究进展

多不饱和脂肪酸是细胞膜磷脂的重要组成成份,影响细胞膜的稳定性.它具有广泛的生物学功能,包括细胞内信号传导通路、基因表达和细胞凋亡的调控等.主要从细胞膜脂质的组成,细胞膜的流动性及膜脂质过氧化等方面对多不饱和脂肪酸对细胞膜功能的影响进行了综述.     

Enterocyte mitochondrial dysfunction due to oxidative stress

The endogenous production of H2O2 in isolated rat intestinal mitochondria and oxidant induced damage to mitochondria were examined. There was an appreciable amount of H2O2 production in presence of succinate, glutamate and pyruvate, while the presence of rotenone with succinate further increased production. Superoxide generated by the X-XO system induced membrane permeability transition (MPT), calcium influx, lipid peroxidation and changes in membrane fluidity in mitochondria. A decreased mitochondrial ATPase activity and uncoupling of respiration was also observed. Spermine inhibited swelling induced by X-XO and also blocked the calcium influx and reversed the membrane fluidity changes.     

Exposure of <Emphasis Type="Italic">Porphyromonas gingivalis</Emphasis> to Red Light in the Presence of the Light-Activated Antimicrobial Agent Toluidine Blue Decreases Membrane Fluidity

Porphyromonas gingivalis, one of the etiological agents of periodontitis, can be killed by red light in the presence of toluidine blue. The purpose of this study was to determine whether this light-induced killing was accompanied by changes in the fluidity of the organism's cytoplasmic membrane. A suspension of the organism was exposed to red light in the presence of toluidine blue, and the membrane fluidity was monitored spectrofluorimetrically by using the membrane probe trimethylammonium diphenyl hexatriene. The fluidity of the organism's cytoplasmic membrane was found to decrease significantly during lethal photosensitization, and this was accompanied by membrane condensation and vacuolation of the cells. Although changes in membrane fluidity are often attributable to lipid peroxidation, malonaldehyde (a product of lipid peroxidation) was not detectable. The disruption of membrane functions associated with a decreased membrane fluidity may contribute to the bactericidal effect of light-activated toluidine blue. Received: 12 October 2001 / Accepted: 7 December 2001     

Age-Related Differences in Synaptosomal Peroxidative Damage and Membrane Properties

Young, adult, and old rats were used to study the effect of age on the integrity and functioning of brain synaptosomes. An evaluation was made of the differences in lipid composition, membrane fluidity, Na+, K(+)-ATPase activity, and susceptibility to in vitro lipid peroxidation. There was an age-related increase in synaptosomal free fatty acids, with no modification in acyl chain composition, and a decrease in membrane phospholipids which increased the cholesterol/phospholipid mole ratio. With altered lipid composition, there was a corresponding age-dependent decrease in membrane fluidity, a reduction of Na+, K(+)-ATPase activity, and an overall greater susceptibility to in vitro lipid peroxidation. Furthermore, lipid peroxidation promoted strong modifications of the membrane fluidity, lipid composition, and Na+,K(+)-ATPase activity just as aging did, thus indicating a possible contribution of oxidative damage to ageing processes. The cases studied revealed that the greater responsiveness of old membranes to in vitro lipid peroxidation resulted in the highest degree of membrane alteration, indicating that all pathological states known to promote a peroxidative injury can have even more dramatic consequences when they take place in old brain.     

谷胱甘肽的抗线粒体脂质过氧化作用

谷胱甘肽是细胞内重要的抗氧化损伤物质之一．以NADH诱导的牛心肌线粒体脂质过氧化体系为模型,研究了谷胱甘肽的抗氧化作用．结果表明,一定浓度的谷胱甘肽能够部分抑制该体系中线粒体的脂质过氧化．保护组的丙二醛含量为损伤组72．5％;线粒体的膨胀度较损伤组降低;细胞色素C氧化酶及ATP酶活力分别较损伤组提高了1．5及2．2倍．     

Amyloid β-Peptides Increase Annular and Bulk Fluidity and Induce Lipid Peroxidation in Brain Synaptic Plasma Membranes

Abstract: Amyloid β-peptides (Aβ) may alter the neuronal membrane lipid environment by changing fluidity and inducing free radical lipid peroxidation. The effects of Aβ_1–40 and Aβ_25–35 on the fluidity of lipids adjacent to proteins (annular fluidity), bulk lipid fluidity, and lipid peroxidation were determined in rat synaptic plasma membranes (SPM). A fluorescent method based on radiationless energy transfer from tryptophan of SPM proteins to pyrene and pyrene monomer-eximer formation was used to determine SPM annular fluidity and bulk fluidity, respectively. Lipid peroxidation was determined by the thiobarbituric acid assay. Annular fluidity and bulk fluidity of SPM were increased significantly ( p ≤ 0.02) by Aβ_1–40. Similar effects on fluidity were observed for Aβ_25–35 ( p ≤ 0.002). Increased fluidity was associated with lipid peroxidation. Both Aβ peptides significantly increased ( p ≤ 0.006) the amount of malondialdehyde in SPM. The addition of a water-soluble analogue of vitamin E (Trolox) inhibited effects of Aβ on lipid peroxidation and fluidity in SPM. The fluidizing action of Aβ peptides on SPM may be due to the induction of lipid peroxidation by those peptides. Aβ-induced changes in neuronal function, such as ion flux and enzyme activity, that have been reported previously may result from the combined effects of lipid peroxidation and increased membrane fluidity.     

Variety-specific response of wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) leaf mitochondria to drought stress

The main objective of the present work was to examine leaf respiratory responses to dehydration and subsequent recovery in three varieties of winter wheat (Triticum aestivum L.) known to differ in their level of drought tolerance. Under dehydration, both total respiration and salicylhydroxamic acid (SHAM)-resistant cytochrome (Cyt) pathway respiration by leaf segments decreased significantly compared with well-watered plants. This decrease was more pronounced in the drought-sensitive Sadovo and Prelom genotypes. In contrast, the KCN-resistant SHAM-sensitive alternative (Alt) pathway became increasingly engaged, and accounted for about 80% of the total respiration. In the drought-tolerant Katya variety, increased contribution of the Alt pathway was accompanied by a slight decrease in Cyt pathway activity. Respiration of isolated leaf mitochondria also showed a variety-specific drought response. Mitochondria from drought-sensitive genotypes had low oxidative phosphorylation efficiency after dehydration and rewatering, whereas the drought-tolerant Katya mitochondria showed higher phosphorylation rates. Morphometric analysis of leaf ultrastructure revealed that mitochondria occupied approximately 7% of the cell area in control plants. Under dehydration, in the drought-sensitive varieties this area was reduced to about 2.0%, whereas in Katya it was around 6.0%. The results are discussed in terms of possible mechanisms underlying variety-specific mitochondrial responses to dehydration.