铝处理下小麦幼苗根系膜脂过氧化作用 和质膜微囊ATP酶活性的变化

采用水培的方法研究了Al对小麦（Triticum aestivum L.cv Yangmai No.5）幼苗的生长、根尖组织膜脂过氧化作用、保护酶的活性和质膜结合酶H     

镉胁迫对芥蓝根系质膜过氧化及ATPase活性的影响

水培条件下,以“香港白花”芥蓝品种为供试材料,研究4种不同浓度镉（0、1.0、2.0、4.0、8.0 mg/L Cd）处理对芥蓝幼苗根系质膜过氧化及ATPase活性的影响。结果表明,与对照相比,随着Cd处理浓度的增加,芥蓝根系活力呈现降低的变化趋势,而根系超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性以及丙二醛（MDA）、H2O2含量和O2-产生速率表现出升高的趋势,表明芥蓝受到活性氧物质的胁迫。1.0、2.0 mg/L Cd浓度处理下的H2O2含量与对照差异不显著,而O2-产生速率则在1.0 mg/L浓度处理下与对照差异不显著。随着Cd处理浓度的增加,芥蓝根系质膜H -ATPase和Ca2 -ATPase活性呈现出先增后减的变化趋势。1.0 mg/LCd浓度处理时,H -ATPase和Ca2 -ATPase活性与对照差异不显著（P > 0.05）,而在2.0、4.0和8.0 mg/LCd处理时,两种ATPase活性显著降低（P < 0.05）,并且与膜脂过氧化水平呈极显著的负相关（R2 > 0.969）。因此,低浓度Cd处理对芥蓝根系质膜两种ATPase活性影响较小,较高浓度Cd处理使芥蓝根系活力和质膜ATPase的损伤加重。     

铁镉互作对水稻脂质过氧化及抗氧化酶活性的影响

利用营养液培养方法,以‘沈农265’为供试品种,研究不同Fe(0、0.1、0.25、0.5mmolFe2+·L-1)、Cd(0、0.1、1.0μmolCd2+·L-1)处理对水稻植株体内脂质过氧化及抗氧化酶活性的影响.结果表明:单独供应Fe显著降低了水稻地上部和根系生物量,同时供应Cd后生物量不再下降;单独供应Cd降低了根系中丙二醛(MDA)和可溶性蛋白含量,而同时供应Fe时这种降低作用消失.Fe处理降低了水稻地上部和根系Cd含量,Cd处理也降低了Fe含量,两者表现出明显的相互抑制作用.高Cd(1.0μmol·L-1)和Fe互作,增加了水稻根系中MDA和可溶性蛋白含量,降低了超氧化物岐化酶(SOD)和过氧化氢酶(CAT)活性.表明在低Cd环境中为水稻提供一定数量的外源Fe能降低植株Cd含量;但高Cd胁迫将降低水稻对Fe的吸收,并导致植株体内产生脂质过氧化.     

Blue light effects on stomata are mediated by the guard cell plasma membrane redox system distinct from the proton translocating ATPase

Abstract. The effects of blue light on stomata are critically analysed. Blue-light-induced increase in stomatal conductance is preceded by membrane hyperpolarization, proton efflux, potassium uptake and malate synthesis in guard cells. Hypothetically, a flavin containing plasma membrane redox system can pump protons out of guard cells on illumination with blue light. It is proposed that this electrogenic proton pump requires NAD(P)H but does not involve ATP/ATPase.     

Up-regulation of plasma membrane-associated redox activities in neuronal cells lacking functional mitochondria

Mitochondria-deficient cells (rho(o) cells) survive through enhanced glycolytic metabolism in the presence of pyruvate and uridine. The plasma membrane redox system (PMRS) contains several NAD(P)H-related enzymes and plays a key role in maintaining the levels of NAD(+)/NADH and reduced coenzyme Q. In this study, rho(o) cells were used to investigate how the PMRS is regulated under conditions of mitochondrial dysfunction. rho(o) cells exhibited a lower oxygen consumption rate and higher levels of lactate than parental cells, and were more sensitive to glycolysis inhibitors (2-deoxyglucose and iodoacetamide) than control cells. However, they were more resistant to H(2)O(2), consistent with increased catalase activity and decreased oxidative damage (protein carbonyls and nitrotyrosine). PM-associated redox enzyme activities were enhanced in rho(o) cells compared to those in control cells. Our data suggest that all PMRS enzymes and biomarkers tested are closely related to the ability of the PMs to maintain redox homeostasis. These results illustrate that an up-regulated PM redox activity can protect cells from oxidative stress as a result of an improved antioxidant capacity, and suggest a mechanism by which neurons adapt to conditions of impaired mitochondrial function.     

Effects of acute manganese chloride exposure on lipid peroxidation and alteration of trace metals in rat brain

Although manganese (Mn) is an essential element, exposure to excessive levels of Mn and its accumulation in the brain can cause neurotoxicity and extrapyramidal syndrome. We have investigated the differences in the accumulated levels of Mn, the degree of lipid peroxidation, and its effects on the levels of trace elements (Fe, Cu, and Zn) in various regions in the brain of rats having undergone acute Mn exposure. The rats in the dose—effect group were injected intraperitoneally (ip) with MnCl₂ (25, 50, or 100 mg MnCl₂/kg) once a day for 24 h. The Mn significantly accumulated (p<0.05) in the frontal cortex, corpus callosum, hippocampus, striatum, hypothalamus medulla, cerebellum, and spinal cord in each case. The rats in the timecourse group were ip injected with MnCl₂ (50 mg MnCl₂/kg) and then monitored 12, 24, 48, and 72 h after exposure. The Mn accumulated in the frontal cortex, corpus callosum, hippocampus, striatum hypothalamus, medulla, cerebellum, and spinal cord after these periods of time, In both the dose—effect and time-course studies, we observed that the concentration of malondialdehyde, an end product of lipid peroxidation, increased significantly in the frontal cortex, hippocampus, striatum, hypothalamus, medulla, and cerebellum. However, no relationship between the concentrations of Mn in the brain and the extent of lipid peroxidation was observed. In addition, we found that there was a significant increase (p<0.05) in the level of Fe in the hippocampus, striatum, hypothalamus, medulla, and cerebellum, but the Cu and Zn levels had not changed significantly. These findings indicated that Mn induces an increase in the iron level, which provides direct evidence for Fe-mediated lipid peroxidation in the rats' brains; these phenomena might play important roles in the mechanisms of Mn-induced neurotoxicology.     

低温胁迫下喜旱莲子草幼苗膜脂过氧化及保护酶活性的变化

分别在2℃和8℃低温胁迫下,对入侵种喜旱莲子草幼苗抗氧化酶活性进行了研究。与常温28℃的结果相比较,MDA含量、细胞膜透性在8℃条件下变化不明显,2℃处理36h后均显著上升。2℃时SOD、CAT和POD活性在较短时间内(12h)显著升高,随后逐渐下降,CAT活性在48h后受到低温胁迫的严重抑制。8℃处理条件下3种保护酶活性在48h内均有显著升高,但升幅明显小于2℃处理的升幅。8℃低温处理不是抑制而是促进了3种保护酶活性的提高。复温结果显示,8℃低温胁迫的喜旱莲子草幼苗和对照无生长差异,2℃低温胁迫下幼苗表现出形态特征差异。     

ATPase activity of isolated plasma membrane vesicles of leaves of Elodea as affected by thiol reagents and NADH/NAD+ ratio

The goal of this study was to test the hypothesis that the plasma membrane-bound ATPase activity is influenced by the redox poise of the cytoplasm. Purified plasma membrane vesicles from leaves of Elodea canadensis Michx. and E. nuttallii (Planch.) St. John were isolated using an aqueous polymer two-phase batch procedure. The distribution of marker enzyme activities confirmed the plasma membrane origin of the vesicles. The vesicles exhibited NADH-ferricyanide reductase activity, indicating the presence of a redox chain in the plasma membrane. The K⁺, Mg²⁺-ATPase activity associated with these vesicles was inhibited by the sulfhydryl reagents N-ethylmaleimide and glutathione (GSSG). Furthermore the activity was inhibited by NAD⁺. This inhibition by NAD⁺ was relieved by increasing the NADH/NAD⁺ ratio. The possibility that the ATPase activity is regulated by the cytoplasmic NAD(P)H/ NAD(P)⁺ ratio is discussed, as well as the role of a plasma membrane-bound redox chain.     

Lipid peroxidation in purified plasma membrane fractions of rat liver in relation to the hepatoxicity of carbon tetrachloride

Preparations of rat liver sinusoidal plasma membrane have been tested for their ability to metabolize the hepatotoxin carbon tetrachloride (CCl4) to reactive free radicals in vitro and compared in this respect with standard preparations of rat liver microsomes. The sinusoidal plasma membranes were relatively free of endoplasmic reticulum-associated activities such as the enzymes of the cytochrome P450 system and glucose-6-phosphatase. CCl4 metabolism was measured as (i) covalent binding of [14C]-CCl4 to membrane protein, (ii) electron spin resonance spin-trapping of CCl3. radicals and (iii) CCl4-induced lipid peroxidation. By all of these tests, purified sinusoidal plasma membranes were found unable to metabolize CCl4. The fatty acid composition of the plasma membranes was almost identical to that of the microsomal preparation and both membrane fractions exhibited similar rates of the lipid peroxidation that was stimulated non-enzymically by gamma-radiation or incubation with ascorbate and iron. The absence of CCl4-induced lipid peroxidation in the plasma membranes seems to be due, therefore, to an absence of CCl4 activation rather than an inherent resistance to lipid peroxidation. We conclude that damage to the hepatocyte plasma membrane during CCl4 intoxication is not due to a significant local activation of CCl4 to CCl3. within that membrane.     

Cadmium-induced liver, heart, and spleen lipid peroxidation in rats and protection by selenium

The purpose of this study was to evaluate the effects of cadmium-induced peroxidative damage to rat liver, heart, and spleen. Sprague-Dawley rats were injected subcutaneously with a single dose of 25, 125, 500, or 1250 μg Cd/kg and evaluated 6, 12, 24, or 72 h later. Liver, heart, and spleen were analyzed for lipid peroxidation and Fe, Cu, Zn, Se, and Cd concentrations. Data showed that Cd produced enhanced lipid peroxidation in the liver, heart, and spleen. These Cd-induced changes were accompanied by a significant rise in liver, heart, and spleen Fe and Cu, and a fall in spleen Zn and liver, heart, and spleen Se. Concurrent treatment with Se and Cd reduced the Cd-induced alterations in liver, heart, and spleen peroxidation and essential metal levels. Data suggest that lipid peroxidation is associated with cadmium toxicity and that Se was found effective in preventing lipid peroxidation.     

低温下水稻幼苗叶片细胞膜膜脂过氧化和膜磷脂脱酯化反应

水稻幼苗遭遇冷胁迫（１℃,光照强度１５０μｍｏｌ·ｍ－２·ｓ－１）２ｄ,其叶片丙二醛（ＭＤＡ）含量明显增加,酸性磷酸酯酶活性也增加,同时无机磷含量也增加。３０ｍｍｏｌ／Ｌ的ＣａＣｌ２浸泡种子１ｄ则削弱了冷胁迫的这种作用。Ｈ２Ｏ２和甲基紫精（ＭＶ）均有刺激幼苗叶片和离体根质膜酸性磷酸酯酶活性的作用。     

Microsomal redox systems in brown adipose tissue: high lipid peroxidation,low cholesterol biosynthesis and no detectable cytochrome P-450

The presence of redox systems in microsomes of brown adipose tissue (BAT) in cold exposed rats was investigated and compared with liver. BAT microsomes showed high activity of lipid peroxidation measured both by the formation of malondialdehyde (MDA) and by oxygen uptake. NADH and NADPH dependent cytochrome c reductase activity were present in both BAT and liver microsomes. Aminopyrine demethylase and aniline hydroxylase activities, the characteristic detoxification enzymes in liver microsomes could not be detected in BAT microsomes. BAT minces showed very poor incorporation of [1-¹⁴C]acetate and [2-¹⁴C]-mevalonate in unsaponifiable lipid fraction compared to liver. Biosynthesis of cholesterol and ubiquinone, but not fatty acids, and the activity of 3-hydroxy-3-methyl glutaryl CoA reductase appear to be very low in BAT. Examination of difference spectra showed the presence of only cytochrome b ₅ in BAT microsomes. In addition to the inability to detect the enzyme activities dependent on cytochrome P-450, a protein with the characteristic spectrum, molecular size in SDS-PAGE and interaction with antibodies in double diffusion test, also could not be detected in BAT microsomes. The high activity of lipid peroxidation in microsomes, being associated with large oxygen uptake and oxidation of NADPH, will also contribute to the energy dissipation as heat in BAT, considered important in thermogenesis.Abbreviations BAT Brown Adipose Tissue - MDA malondialdehyde     

Spin label studies on rat liver and heart plasma membranes: Effects of temperature,calcium, and lanthanum on membrane fluidity

The structures of rat liver and heart plasma membranes were studied with the 5-nitroxide stearic acid spin probe, I(1 2,3). The polarity-corrected order parameters (S) of liver and heart plasma membranes were independent of probe concentration only if experimentally determined low I(1 2,3)/lipid ratios were employed. At higher probe/lipid ratios, the order parameters of both membrane systems decreased with increasing probe concentration, and these effects were attributed to enhanced nitroxide radical interactions. Examination of the temperature dependence of approximate and polarity-corrected order parameters indicated that lipid phase separations occur in liver (between 19° and 28°C) and heart (between 21° and 32°C) plasma membranes. The possibility that a wide variety of membrane-associated functions may be influenced by these thermotropic phase separations is considered. Addition of 3.9 mM CaCl₂ to I(1 2,3)-labeled liver plasma membrane decreased the fluidity as indicated by a 5% increase in S at 37°C. Similarly, titrating I(1 2,3)-labeled heart plasma membranes with either CaCl₂ or LaCl₃ decreased the lipid fluidity at 37°C, although the magnitude of the La³⁺ effect was larger and occurred at lower concentrations than that induced by Ca²⁺; addition of 0.2 mM La³⁺ or 3.2 mM Ca²⁺ increased S by approximately 7% and 5%, respectively. The above cation effects reflected only alterations in the membrane fluidity and were not due to changes in probe–probe interactions. Ca²⁺ and La³⁺ at these concentrations decrease the activities of such plasma membrane enzymes as Na⁺, K⁺-ATPase and adenylyl cyclase, and it is suggested that the inhibition of these enzymes may be due in part to cation-mediated decreases in the lipid fluidity.     

Partial characterization of the inhibitory effect of lipid peroxidation on the ouabain-insensitive Na-ATPase of rat kidney cortex plasma membranes

The present work evaluates the effect of lipid peroxidation on the ouabain-insensitive Na-ATPase of basolateral plasma membranes from rat kidney proximal tubular cells as an indirect way to study the lipid dependence of this enzyme. An inverse relationship between lipid peroxidation and Na-ATPase activity was found. This effect was due neither to a change in the optimalK _m of the system for Na⁺ nor for the substrate Mg : ATP, nor the optimal pH value of the medium. The optimal temperature value, however, was shifted toward a higher value. There was also an increase of the apparent energy of activation in the region of temperatures above the transition point (20°C) with increase in lipid peroxidation. Peroxidized membranes incubated with phosphatidylcholine from soybean restored their Na-ATPase activity. On the other hand, the Na-ATPase activity was sensitive to oleoly lysophosphatidylcholine. These results suggest that lipid peroxidation might be affecting the Na-ATPase activity through either an increase of peroxidized phospholipids, which might change the membrane fluidity of the lipid microenvironment of the ATPase molecules, or through a direct effect of lysophospholipids released during the lipid peroxidation.     

冷锻炼对低温胁迫下夏威夷椰子膜脂过氧化及保护酶活性的影响

在－5℃低温胁迫下,夏威夷椰子（Pritchardia gaudichaudii H.Wendl.)幼苗叶片的丙二醛（MDA）含量逐渐增加,表明膜脂过氧化作用逐渐增强;含水量不断下降;细胞保护酶中的超氧化物歧化酶（SOD）、过氧化物酶（POD) 过氧化氢酶（CAT）酶活性均先升高,然后下降。冷锻炼处理可以减缓夏威夷椰子膜脂过氧化作用的增强,促进SOD酶活性的提高,同时抑制POD和CAT酶活性的变化,因而使夏威夷椰子幼苗的抗寒性得以提高,在－5℃低温胁迫下的半致死时间从1.6d延长到2.2d。     

Comparison of the redox activities in plasma membranes from roots and shoots of etiolated bean seedlings

Summary Plasma membrane (PM) vesicles were purified in parallel from the roots and shoots of 6-day-old etiolated bean (Phaseolus vulgaris L.) seedlings, grown in water culture at 25 °C, by aqueous polymer two-phase partitioning. The purity of PM fractions was determined by measuring the activity of known marker enzymes (vanadate-sensitive Mg-ATPase, 1,3--glycan synthase, latent ID-Pase, cytochromec oxidase, and antimycin-A-insensitive cytochromec reductase). NADH-(acceptor) oxidoreductase activities were determined with the following electron acceptors: ferricyanide, cytochromec, duroquinone, monodehydroascorbate, Fe³⁺-EDTA, and oxygen. Cytochromeb content was also determined. In general, results show that redox activities are higher in the root PM than in the shoot PM which follows the glycan synthase II (PM marker) pattern. The relative activities of the distinct redox enzymes measured (activity profile) are remarkably similar in the root and shoot PM preparations. The cytochromeb content and level of ascorbate reduction were also similar in both plant organs. However, the ratio of NADH-(acceptor) oxidoreductase activity to cytochrome content was signifcantly higher in roots when compared to the shoots.Abbreviations CCO cytochromec oxidase - CCR cytochromec reductase - GSII 1,3--glycan synthase - MF microsomal fraction - N-CC-OR NADH-cytochromec oxidoreductase - N-DQ-OR NADH-duroquinone oxidoreductase - N-FC-OR NADH-ferricyanide oxidoreductase - N-FE-OR NADH-Fe³⁺-EDTA oxidoreductase - N-MDA-OR NADH-monodehydroascorbate oxidoreductase - PM plasma membrane     

大气CO2浓度升高对毛竹叶片膜脂过氧化和抗氧化系统的影响

为了解竹子对大气CO2浓度升高的生理响应,为气候变化背景下的竹林适应性管理提供理论依据,运用开顶式气室(OTCs)设置了3个CO2处理浓度(环境大气、500和700μmol·mol-1),探讨了大气CO2浓度升高对毛竹(Phyllostachys edulis)叶片光合色素、膜脂过氧化和抗氧化系统的影响。结果表明:与环境大气比较,500μmol·mol-1浓度处理30d时对毛竹叶片光合色素、膜脂过氧化和抗氧化系统影响并不明显,仅叶片CAT活性显著降低;随着处理时间的延长,对毛竹叶片膜脂过氧化和抗氧化系统的影响逐渐显现,至处理90d时,除叶片可溶性糖含量无明显变化,其他测定指标均有显著变化;700μmol·mol-1浓度处理在不同时间上对毛竹叶片膜脂过氧化和抗氧化系统的影响均较500μmol·mol-1CO2浓度处理明显,处理30d时毛竹叶片可溶性糖含量和抗氧化酶活性有明显变化,处理90d时,各项测定指标均有显著变化;研究表明大气CO2浓度升高一定程度上能增强毛竹的抗氧化能力,但光合产物的过量积累也会造成碳水化合物源-库失衡和Rubisco的再生受到反馈作用抑制。     

Antioxidant effect of vitamin E and glutathione on lipid peroxidation in boar semen plasma

The protective effect of vitamin E and reduced glutathione (GSH) against lipid peroxidation in boar semen plasma was studied. The lipid peroxidation, measured by the test for thiobarbituric acid reactive substances (TBARS), doubled in the presence of the lipid peroxidation Fe²⁺-sodium ascorbate-inducing system. The ascorbate-induced TBARS were inhibited by about 62% through the water-soluble vitamin E analog (TROLOX) and about 57% by GSH. In the in vivo experiments, 7 wk of oraldl-α-tocopherol acetate (1000 IU/d/animal) administration caused a significant fall in the level of the semen plasma TBARS, from 2.2±0.09 to 1.2±0.13 nmol MDA/mL. The semen plasma superoxide dismutase (SOD) and GSSG tended to increase with the time of vitamin E administration, but the increment did not reach a significant level by the seventh week. The vitamin E supplementation significantly increased the number of spermatozoa per 1 cm³ of ejaculate. The protective role of vitamin E and GSH with respect to boar semen against fatty acid peroxidation and a positive influence of vitamin E supplementation on semen quality have been evidenced.     

The induction of freezing tolerance in jack pine seedlings: The role of root plasma membrane H+- ATPase and redox activities

The acquired freezing tolerance of jack pine seedlings (Pinus banksiana Lamb.) conditioned at low nonfreezing temperatures and short photoperiods was determined by comparison of seedling survival to that of nonconditioned (control) seedlings following exposure to ?5 and ?10°C. Compared to that of controls, survival of conditioned seedlings was markedly increased following exposure to freezing temperatures. A 1-week conditioning treatment significantly increased the survival of the seedlings after exposure to ?5°C, but was less effective on seedlings exposed to ?10°C. Conditioning periods of 2 and 4 weeks resulted in higher survival of seedlings exposed to both ?5 and ?10°C. The changes of two root-plasma-membrane-associated enzyme activities, H⁺-ATPase and NADH-dependent ferricyanide reductase, were studied in enriched plasma membrane fractions during conditioning and after freezing. Post-freezing activities of both enzymes were enhanced by conditioning at low temperatures and short photoperiods. These changes may be related to the increased frost hardiness also induced by conditioning.     

Free fatty acids,lipid peroxidation,and lysosomal enzymes in experimental focal cerebral ischemia in primates: Loss of lysosomal latency by lipid peroxidation

Experimental focal cerebral ischemia was produced in monkeys (Macaca radiata) by occlusion of the right middle cerebral artery (MCA). The release of the lysosomal glycosidases, -d-hexosaminidase, -l-fucosidase and -d-mannosidase into the soluble fraction in the right basal ganglia of the experimental animals was measured at different periods from 30 min to 12 hr after occlusion and compared with the corresponding sham operated control animals. There was a significant increase in the released lysosomal enzymes in the MCA occluded animals at all periods and particularly at 4 hr after occlusion. The CSF from the experimental animals also showed elevated levels of hexosaminidase and fucosidase. The free fatty acids (FFA) measured in the basal ganglia at 30 min and 2 hr after occlusion showed a 100 fold increase in the experimental animals. The predominant fatty acid released was linoleic acid (18:2) followed by arachidonic acid (20:4). Lipid peroxidation in the basal ganglia measured by the thiobarbituric acid (TBA) reaction in the presence or absence of ascorbic acid also showed a significant increase in the experimental animals at all periods with a maximum at 30 min to 2 hr after occlusion. In order to assess whether lipid peroxidation causes damage to the lysosomes and release of the enzymes, a lysosome enriched P₂ fraction from the normal monkey basal ganglia was prepared and the effect of peroxidation studied. Maximum peroxidation in the P₂ fraction was observed in the presence of arachidonic acid, ascorbic acid and Fe²⁺. There was a good correlation between the extent of lipid peroxidation and the in vitro release of lysosomal hexosaminidase from the P₂ fraction. Anti-oxidants which strongly inhibited lipid peroxidation in the P₂ fraction prevented the release of hexosaminidase. The results suggested that in ischemia produced by MCA occlusion lipid peroxidation which damages the lysosomal membrane causes the release of lysosomal hydrolytic enzymes.Abbreviations used BHA butylated hydroxyanisole - BHT butylated hydroxytoluene - FFA free fatty acids - MCA middle cerebral artery - MDA malonaldehyde - PUFA polyunsaturated fatty acids - TBA thiobarbituric acid