叶绿体光合代谢中活性氧的产生与清除

有氧代谢不可避免产生活性氧(ROS),叶绿体的PSI和PSII反应中心均是ROS产生的主要位点。叶绿体产生的ROS主要有超氧阴离子(O2-)、过氧化氢(H2O2)、羟自由基(.OH)和单线氧(1O2),其中在PSI产生的O2-将进一步产生H2O2和.OH,而1O2产生在PSII。正常生理代谢条件下,叶绿体内抗氧化系统和光能吸收利用的调节保持活性氧产生和消灭的平衡,不会影响植物的正常生理功能。     

干旱胁迫对不同根型苜蓿根系生长及根际土壤细菌的影响

为明确干旱胁迫对根茎型清水紫花苜蓿、直根型陇东紫花苜蓿、根蘖型公农4号杂花苜蓿根系生长及根际土壤细菌群落的影响,采用盆栽试验,运用16S rRNA基因测序技术,研究了幼苗期干旱胁迫下各根型苜蓿根系生长及根际土壤细菌群落结构的变化。结果表明：干旱胁迫下各根型苜蓿的Chao1和ACE丰富度指数均在中度胁迫下最大,Simpson和Shannon-wiener多样性指数各处理间差异不显著;根际土壤细菌群落均以变形菌门、绿弯菌门、类杆菌门、放线菌门和厚壁菌门为主,干旱胁迫均显著增加了变形菌门和厚壁菌门的相对丰度,显著降低了绿弯菌门的相对丰度,但类杆菌门和放线菌门先提高后下降。统计学分析显示,幼苗期干旱胁迫显著影响各根型苜蓿生长发育,随胁迫程度增加,其株高、地上生物量、地下生物量、根系活力、根体积、根系总长均显著降低,根冠比先增加后下降且在中度胁迫时达到最大值。重度胁迫下,清水苜蓿的株高、根系活力显著大于其他品种,而根冠比、根系干重显著小于其他品种;陇东苜蓿的根长、根尖数均显著大于其他品种;根系平均直径、根系总表面积各根型苜蓿间差异不显著。研究结果为植物的抗干旱胁迫以及提高各根型苜蓿在干旱胁迫下的水分利用提供参考。     

干旱胁迫下紫花苜蓿根系形态变化及与水分利用的关系

采用盆栽实验方法研究了紫花苜蓿(品种:陇东和阿尔冈金)根系形态、生物量、蒸腾耗水量等对持续干旱的反应及与水分利用效率(WUE)间的关系,以期揭示紫花苜蓿对干旱胁迫的适应机制。结果表明:干旱胁迫使得紫花苜蓿根系形态特征在年季间、茬次间和品种间发生了显著变化,主要表现为主根伸长生长受到抑制、主根直径变细、侧根和根系总长度伸长生长则被促进、根系表面积和直径≥1mm的侧根数目显著增加、根系生物量下降,这是紫花苜蓿对干旱逆境的适应策略,但这种适应性存在限度。另一方面,干旱胁迫条件下紫花苜蓿草产量和蒸腾耗水量也因生长年限、茬次和品种的不同而呈现不同程度的降低。紫花苜蓿根系形态性状(总根长、根系生物量与根冠比)与植株水分利用效率间具有显著的相关性,其中根重对水分效率的影响是第一位的。WUE在根系形态与冠层水分消耗的协同变化下得到有限提高。对干旱的耐性最终表现为第2年第1年、第1茬和第2茬第3茬、陇东阿尔冈金。     

Imaging reactive oxygen species in asthma

Inflammatory processes in asthma are characterized by an infiltration of inflammatory cells including mononuclear phagocytes. It has been observed that mononuclear phagocytes, alveolar macrophages and blood monocytes, release higher quantities of reactive oxygen species in asthmatic patients than in healthy subjects. Chemiluminescence assays were developed to measure the superoxide anion and the other reactive oxygen species. The chemiluminescence response was first analysed with a luminometer, which made it possible to study cells in suspension before and after PMA-stimulation. Secondly a video-imaging camera was used in experiments on adherent cells before and after stimulation with PMA and/or specific stimulus IgE/anti-IgE. Both techniques showed that human alveolar macrophages, blood monocytes, PMN and lymphocytes were spontaneously primed in vivo and were more easily stimulated in asthma. Analysis of adherent cells in vitro may provide give information on the physiological condition of adherent cells in vivo.     

Identification of the Arabidopsis dry2/sqe1‐5 mutant reveals a central role for sterols in drought tolerance and regulation of reactive oxygen species

Squalene epoxidase enzymes catalyse the conversion of squalene into 2,3‐oxidosqualene, the precursor of cyclic triterpenoids. Here we report that the Arabidopsis drought hypersensitive/squalene epoxidase 1‐5 (dry2/sqe1‐5) mutant, identified by its extreme hypersensitivity to drought stress, has altered stomatal responses and root defects because of a point mutation in the SQUALENE EPOXIDASE 1 (SQE1) gene. GC‐MS analysis indicated that the dry2/sqe1‐5 mutant has altered sterol composition in roots but wild‐type sterol composition in shoots, indicating an essential role for SQE1 in root sterol biosynthesis. Importantly, the stomatal and root defects of the dry2/sqe1‐5 mutant are associated with altered production of reactive oxygen species. As RHD2 NADPH oxidase is de‐localized in dry2/sqe1‐5 root hairs, we propose that sterols play an essential role in the localization of NADPH oxidases required for regulation of reactive oxygen species, stomatal responses and drought tolerance.     

5种石斛及其组织培养物对活性氧的清除作用

采用化学发光法,以3种活性氧R0S(02、     

干旱胁迫对不同根型苜蓿根系构型的影响

采用盆栽试验,比较播种当年及生长第2年对照、中度、重度干旱胁迫下根茎型、直根型、根蘖型苜蓿根系平面、立体几何构型和分形特征差异,以探究不同根型苜蓿对干旱的适应策略。结果表明：随干旱胁迫增加,各根型苜蓿根系总长度、总表面积、总体积和平均直径均减小;各根型苜蓿的根系拓扑指数较小,根系分支模式为叉状分支结构;各根型苜蓿的根系具有较好的分形特征,其分形维数较小,而分形丰度和平均连接长度均较大,表明其根系分支相对简单,但空间拓展能力强,有利于对营养空间的占有;各根型苜蓿的总分支较小、逐级分支率较大,有助于资源的快速获取和促进主根的向下生长。对根系构型参数进行主成分分析,根系总表面积、分形丰度、根长、根体积、分形维数和比根长6个根系构型参数能较好反映不同根型苜蓿根系构型特征。重度胁迫下,根茎型、根蘖型苜蓿的根系总长度、总表面积、总体积、比根长、比表面积、平均连接长度均大于直根型苜蓿,表明根茎型、根蘖型苜蓿适应干旱环境的能力强于直根型苜蓿。     

Effect of lanthanum ions (La3+) on the reactive oxygen species scavenging enzymes in wheat leaves

Physiological effects of lanthanum ions on the activities of the enzymes in the reactive oxygen species (ROS) scavenging system in leaves of wheat (Triticum aestivum L.) seedlings were studied. Wheat leaves treated in Hogland solution with 0.1 mM LaCl₃ for 48 h showed increased levels of superoxide dismutase (SOD), catalase (CAT), ascorbate-specific peroxidase (AsA-POD), and dehydroascorbate reductase (DHAR). However, a minor effect was observed on the levels of monodehydroascorbate reductase (MDAR) and glutathione reductase (GR), which regulate the release of energy required by the ROS scavenging system. The whole system was linked up by H⁺ transmission. Our results indicated that the activities of the enzymes that function directly to remove ROS were elevated by La³⁺ treatment, which is consistent with the observations that La³⁺-treated plants had increased tolerance to environmental stresses. The remaining levels of MDAR and GR suggested that these two enzymes might be regulated differently from that of the other four enzymes studied.     

光果甘草毛状根培养过程中对活性氧清除能力和总黄酮含量的变化

采用化学发光法, 分析了光果甘草(Glycyrrhiza glabra L.)毛状根培养过程中对3种活性氧(ROS: O-2(÷)、HO·和H-2O-2)清除能力的动态变化, 并测定了培养过程中总黄酮含量的动态变化. 实验结果表明, 毛状根在对数生长期(20～28 d)对3种ROS都有很强的清除能力,在生长停滞期(29～40 d)对HO·和H-2O-2的清除能力仍维持较高的水平,而对O-2(÷)的清除能力随培养时间的延长逐渐下降.总黄酮含量在对数生长期呈现增加的趋势,至31 d时达到最高含量(0.78%),随培养时间的延长含量逐渐降低.     

野牛草叶片活性氧及其清除系统对水分胁迫的响应

逆境条件下活性氧产生及其清除效率是衡量植物抗性的重要指标,而活性氧对植物组织的氧化伤害和抗氧化酶活性常因材料的遗传或生理差异性而发生变化。以同一基因型的野牛草(Buchloe dactyloides(Nutt.)Engelm'texoka')克隆分株叶片为材料,采用Hoagland营养液培养,研究了10%、20%和30%PEG-6000模拟干旱胁迫下,野牛草叶片活性氧的产生、脂质过氧化和抗氧化酶活性变化规律。结果表明:随着PEG-6000浓度的增加及胁迫时间的延长,超氧阴离子(O2-.)的产生速率、过氧化氢(H2O2)和丙二醛(MDA)含量均显著增加;超氧化物歧化酶(SOD EC1.15.1.1)、愈创木酚过氧化物酶(G-POD EC1.11.1.7)和过氧化氢酶(CATEC1.11.1.6)活性呈先上升后下降的变化趋势;SOD、G-POD与CAT活性达到峰值的时间随PEG-6000浓度的增加而提前。认为水分胁迫下,抗氧化酶可有效清除活性氧自由基,但随胁迫时间的延长,抗氧化酶活性受到抑制。     

Spatio-temporal heterogeneity in Arabidopsis thaliana leaves under drought stress

Using chlorophyll (chl) fluorescence imaging, we studied the effect of mild (MiDS), moderate (MoDS) and severe (SDS) drought stress on photosystem II (PSII) photochemistry of 4-week-old Arabidopsis thaliana. Spatio-temporal heterogeneity in all chl fluorescence parameters was maintained throughout water stress. After exposure to drought stress, maximum quantum yield of PSII photochemistry (F(v)/F(m)) and quantum efficiency of PSII photochemistry (Φ(PSΙΙ)) decreased less in the proximal (base) than in the distal (tip) leaf. The chl fluorescence parameter F(v) /F(m) decreased less after MoDS than MiDS. Under MoDS, the antioxidant mechanism of A. thaliana leaves seemed to be sufficient in scavenging reactive oxygen species, as evident by the decreased lipid peroxidation, the more excitation energy dissipated by non-photochemical quenching (NPQ) and decreased excitation pressure (1-q(p)). Arabidopsis leaves appear to function normally under MoDS, but do not seem to have particular metabolic tolerance mechanisms under MiDS and SDS, as revealed by the level of lipid peroxidation and decreased quantum yield for dissipation after down-regulation in PSII (Φ(NPQ)), indicating that energy dissipation by down-regulation did not function and electron transport (ETR) was depressed. The simultaneous increased quantum yield of non-regulated energy dissipation (Φ(NO)) indicated that both the photochemical energy conversion and protective regulatory mechanism were insufficient. The non-uniform photosynthetic pattern under drought stress may reflect different zones of leaf anatomy and mesophyll development. The data demonstrate that the effect of different degrees of drought stress on A. thaliana leaves show spatio-temporal heterogeneity, implying that common single time point or single point leaf analyses are inadequate.     

干旱胁迫下多裂骆驼蓬(Peganum multisectum Bobr)叶片乙烯释放和多胺含量变化与活性氧积累的关系

通过盆栽土培试验研究了干旱胁迫下多裂骆驼蓬(Peganum multisectum Bobr)叶片乙烯释放、多胺含量、活性氧水平及细胞膜透性的动态变化.结果表明,随着土壤干旱强度的增加和胁迫时间的延长,多裂骆驼蓬叶片内丙二醛(MDA)含量和细胞膜透性呈递增变化趋势;轻度胁迫下,乙烯产生速率、多胺(Put、Spm、Spd)、活性氧(O2-·、H2O2)和MDA含量及多胺氧化酶(PAO)活性随胁迫时间延长无明显变化;中度和重度胁迫初期(胁迫后0～30d)腐胺(Put)、精胺(Spm)和亚精胺(Spd)含量快速提高,乙烯生成速率下降,而O2-·、H2O2、MDA含量和PAO活性相对平稳;胁迫后期(胁迫后45～75d)乙烯生成速率增高,Put、Spm和Spd含量下降, O2-·、H2O2和MDA含量大幅度增加,膜透性增大,且乙烯释放与O2-·、H2O2含量呈显著正相关.表明中度和重度胁迫下多裂骆驼蓬叶片存在乙烯和多胺合成的相互制约,乙烯释放增加诱导活性氧积累导致膜透性急剧增大.     

Intracellular reactive oxygen species mediate suppression of sporulation in Bacillus subtilis under shear stress

Sporulation is an important cellular response to stress that is also significant from a bioreactor operation viewpoint. While sporulating organisms are known to show an enhanced sporulation response under several stress situations, the sporulation response to shear stress has not been investigated thus far. Such a study could be of interest since shear stress, to a greater or lesser degree, is always present in bioreactor operation. In this article, we investigate the sporulation extents of the Gram-positive bacteria Bacillus subtilis at various defined shear levels. We show that, contrary to expectations, shear inhibits sporulation. We found an inverse correlation between the shear rate-dependent specific intracellular reactive oxygen species level (siROS), and the sporulation extent. A 10-fold increase in siROS resulted in about 17-fold decrease in sporulation extent. The involvement of reactive oxygen species (ROS) in sporulation was unknown thus far. Further, through experiments that specifically increased and reduced intracellular ROS (iROS), we established that siROS is responsible for the inhibition of sporulation under shear stress. In addition, we found that shear induced siROS regulated the expression levels of the general stress proteins Ctc and sigma(B). Based on the above, we hypothesize that siROS may regulate suppression of sporulation under high shear by altering sigma(B) and Ctc expression levels, and a model for the same is presented.     

高氧条件下灵芝子实体活性氧含量及其代谢相关酶活性

灵芝Ganoderma lingzhi是最著名的药用真菌之一。本文研究了60%高氧条件下灵芝子实体呼吸速率、灵芝酸（ganoderic acid,GA）含量、总酚含量、活性氧（reactive oxygen species,ROS）含量、丙二醛（malondialdehyde,MDA）含量、抗氧化酶活性、黄嘌呤氧化酶（xanthineoxidase,XOD）活性、琥珀酸脱氢酶（succinic dehydrogenase,SDH）活性、H ⁺-ATP酶活性、Ca ²⁺-ATP酶活性的变化。结果显示,高氧抑制灵芝子实体的呼吸速率;处理前期（第1天）,灵芝子实体内过氧化氢（H₂O₂）和超氧阴离子自由基（O₂ ^-?）含量高于对照组,但随着处理的进行,ROS含量显著减少,MDA积累减少,超氧化物歧化酶（superoxide dismutase,SOD）、过氧化氢酶（catalase,CAT）和SDH活性提高,GA和总酚含量增加。表明一定的环境胁迫压力可以激发灵芝启动自身的抗氧化系统,保护机体免受氧化损伤,并促进相关次生代谢产物的合成。     

两株乳酸杆菌SY13和LJJ对活性氧的耐受性

【目的】从传统发酵乳制品中筛选具有抗氧化能力的乳酸菌菌株并对其抗氧化特性进行评价。【方法】分别利用乳酸杆菌SY13和LJJ完整细胞和无细胞提取物对亚油酸过氧化的抑制效果,对DPPH自由基、羟自由基、超氧阴离子自由基清除能力,对过氧化氢的耐受性以及对亚铁离子的螯合能力和还原活性进行了研究。【结果】结果表明,SY13和LJJ对亚油酸过氧化的最大抑制率分别达到了62.95%和66.16%;两菌株的无细胞提取物清除超氧阴离子和羟自由基的的效果较好,LJJ完整细胞对超氧阴离子和羟自由基没有清除能力;SY13和LJJ对DPPH自由基的清除能力及对亚铁离子的螯合能力都是完整细胞优于无细胞提取物,还原活性分别相当于305 μmol/L和294 μmol/L的L-cysteine。【结论】以上指标测定的结果说明,这两株乳酸杆菌具有较好的抗氧化能力,具有潜在的应用价值。     

光果甘草与乌拉尔甘草清除活性氧能力的比较

采用化学发光法测定了光果甘草（Glycyrrhiza glabra L.）与乌拉尔甘草（G.uralensis Fisch.）中总黄酮和总皂甙对3种重要活性氧（O2^-、OH和H2O2）的清除能力,其中光果甘草对活性氧的清除能力超过乌拉尔甘草;黄酮类化合物对3种活性氧的清除能力强于皂甙类化合物。因此,若以清除活性氧为应用目标,应尽量使用光果甘草。     

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.     

镉胁迫下紫花苜蓿幼苗内源一氧化氮和活性氧的生成

以"甘农三号"紫花苜蓿幼苗为材料,在水培条件下,研究了不同浓度镉(Cd)胁迫下紫花苜蓿根、茎和叶内源一氧化氮(NO)和活性氧(ROS)的生成机制以及根系活力的变化.结果表明:在0~2.0 mmol·L-1范围内,随着Cd浓度的增加,幼苗内NO含量呈现先升高后降低的趋势,最后可维持在略高或持平于对照的水平.幼苗内一氧化氮合成酶(NOS)活性、硝酸还原酶(NR)活性、亚硝酸根离子(NO2-)含量和类胡萝卜素(Car)含量的变化与NO含量变化规律相似却又不全相同.NOS和NR是影响幼苗茎中NO含量的主要因素,NOS、NO2-和NR则是影响叶中NO含量的主要因素,而根中NO含量主要与NOS活性和NO2-含量有较大相关性.随着Cd浓度的增加,幼苗内过氧化氢(H2 O2)含量、丙二醛(MDA)含量、超氧阴离子(O-2·)含量和相对电导率(REC)呈现显著升高趋势,说明高浓度的Cd处理会使ROS大量积累,细胞膜遭破坏,细胞质外流,进而引发膜脂过氧化.随着Cd浓度的增加,紫花苜蓿根系活力的变化为先升高后降低,指示了低浓度Cd处理会促进植物代谢,增强其生命力;而高浓度Cd会致使植株代谢受抑制,细胞受损害.NO和ROS的相关性不大,说明二者虽同为自由基,但它们产生和变化方式大有差别.