仿刺参硫氧还蛋白基因在灿烂弧菌和鳗弧菌刺激下的应激表达特征

分别用灿烂弧菌(Vibrio splendidus)和鳗弧菌(V.anguillarum)对仿刺参(Apostichopus japonicus)进行注射感染试验,取注射后0、3、6、9、12、24 h的仿刺参体壁、肠道、呼吸树、触手和体腔细胞5种组织或细胞进行了实时荧光定量PCR检测,分析硫氧还蛋白(Thioredoxin,Trx)基因在这5种组织或细胞中的表达特征,探讨了硫氧还蛋白在仿刺参先天免疫中的作用。结果显示,Trx基因在仿刺参体壁、肠道、触手、呼吸树及体腔细胞中均表达;在灿烂弧菌刺激下各组织或细胞中Trx基因变化趋势相似,呈现一种"突增-下降-再突增"的双峰型模式;鳗弧菌刺激下Trx基因表达量变化同样呈现先升高后降低的趋势,但与灿烂弧菌组相比反应时间与上调幅度都不同。总而言之,Trx基因在仿刺参体内有组成型和诱导型两种表达模式,并存在表达的组织特异性和病原特异性;Trx基因参与了仿刺参对病原感染的免疫应答,使机体免受氧化胁迫,在抵御外界病原入侵、维持胞内氧化还原状态方面起到重要作用。     

酿酒酵母氧化应激反应的研究进展

所有好氧生长的生物都必须经受由于氧分子的不完全还原形成活性氧类物质而产生的氧化应激反应。酵母细胞受氧化应激后会很快合成自我修复性的物质,以抵御这些不良环境。本文主要概述了酿酒酵母的氧化应激反应,并对该过程中的几种重要的转录调节因子进行阐述。     

细胞自噬与高迁移率族蛋白B-1(HMGB1)介导肿瘤耐药的研究进展

恶性肿瘤可通过多种细胞机制,产生对抗癌药物和放疗的抗性,即所谓耐药现象.细胞自噬是肿瘤细胞耐药的一个重要原因.高迁移率族蛋白B-1(HMGB1)是高度保守的非组蛋白DNA结合蛋白,在DNA结构、基因转录、基因重组、DNA损伤修复以及细胞存活等方面发挥重要的调控作用;HMGB1在细胞内的功能,与其氧化还原状态和细胞定位息...     

Se-scFv-B3对过氧化氢诱导的大鼠乳鼠心肌细胞损伤的保护作用

用H2O2损伤大鼠乳鼠的心肌细胞建立氧化应激损伤模型,考察谷胱甘肽过氧化物酶模拟物Se-scFv-B3对H2O2诱导的大鼠乳鼠心肌细胞氧化损伤的影响.结果表明,Se-scFv-B3能部分增加心肌细胞存活率,减少细胞凋亡,恢复线粒体膜电位,下调Caspase-3活力并降低细胞内活性氧的含量.表明Se-scFv-B3可以保护心肌细胞抵制H2O2诱导的氧化应激损伤.     

Se-scFv-B3对过氧化氢诱导的大鼠乳鼠心肌细胞损伤的保护作用

用H₂O₂损伤大鼠乳鼠的心肌细胞建立氧化应激损伤模型, 考察谷胱甘肽过氧化物酶模拟物Se-scFv-B3对H₂O₂诱导的大鼠乳鼠心肌细胞氧化损伤的影响. 结果表明, Se-scFv-B3能部分增加心肌细胞存活率, 减少细胞凋亡, 恢复线粒体膜电位, 下调Caspase-3活力并降低细胞内活性氧的含量. 表明Se-scFv-B3可以保护心肌细胞抵制H₂O₂诱导的氧化应激损伤.     

细胞色素C修饰电极的制备和性能研究

通过自组装法,把血红蛋白细胞色素C固定于导电聚合物(聚谷氨酸)层,制作成一种微型生物传感器,检测其对过氧化氢和亚硝酸钠的响应.实验发现谷氨酸具有一定的电化学活性,循环伏安图在-0.35 V和-0.05 V出现一对氧化还原峰,而且细胞色素C修饰电极对亚硝酸钠响应所得循环伏安图表明,随着亚硝酸钠加入量增大,还原峰增大.通过吸附法修饰电极,把血红蛋白细胞色素C固定于电极表面,探究修饰电极在对苯二胺中的钝化情况.实验表明:细胞色素C修饰电极可以避免电极钝化的发生.细胞色素C作为一种蛋白酶,使对苯二胺处于氧化状态,从而防止电极表面膜的形成,避免电极钝化的发生.     

硫氧还蛋白f介导的烟草Rubisco活化酶的氧化还原调控

利用菠菜和烟草的硫氧还蛋白f(Trx-f)在不同氧化还原状态下测定了菠菜、拟南芥、烟草和番茄Rubisco活化酶(RCA)活化其Rubisco的活力,实验结果显示菠菜Trx-f只能介导调控菠菜和拟南芥RCA的氧化还原状态,从而改变其活力,而烟草Trx-f介导也只能改变烟草和番茄RCA的氧化还原状态.上述结果表明烟草等物种的单亚型RCA也能受Trx-f介导的氧化还原调控,而且Trx-f介导的RCA氧化还原状态的改变具有种属专一性.     

阿尔茨海默病中的氧化应激及抗氧化治疗

氧化损伤是阿尔茨海默病(AD)的一个重要特征,故"氧化应激假说"提出AD中氧化应激产生较早,可在轻度认知功能障碍及分子水平改变出现即β淀粉样蛋白沉积及神经纤维缠结的形成之前,导致细胞和组织损伤,促进疾病进展.氧化应激中增高的氧化损伤标记水平、抗氧化系统中特定活性的改变、线粒体功能失调及与tau蛋白磷酸化及聚集,β淀粉样蛋白斑块之间联系紧密.本综述探讨AD中的氧化应激假说,抗氧化治疗AD中的可行性及展望.     

应用EQCM研究含有二苯基联苯胺和二亚酰胺官能团的电活性聚合物的氧化还原过程

运用电化学石英晶体微天平技术(EQCM)联合循环伏安法(CV)和计时安培分析法对3种含有二苯基联苯胺和二亚酰胺的电活性聚合物薄膜进行了研究.这些聚合物薄膜具有多个氧化和还原状态.中性聚合物薄膜可以在二苯基联苯胺连接处被电化学氧化或在二亚酰胺处被电化学还原.在氧化还原转化过程期间,聚合物薄膜的电子转移、离子补偿和溶剂运输的动力学取决于聚合物的类型、其所处的氧化还原状态、电位扫描速率和氧化还原转换的方向.确定了包含二苯基联苯胺聚合物在不同电化学条件的氧化还原转化的机理.动力学控制步骤也许与聚合物薄膜在每个氧化还原状态的特定几何结构有关,并受到不同电解质和溶剂的影响.研究了含有二苯基联苯胺和二亚酰胺的电活性聚合物薄膜电子转移反应的级数、反离子补偿和溶剂传输,并定量地测定了氧化还原过程中离子和溶剂进出电活性膜的流量.     

氧化应激在脑缺血损伤中的作用机制

脑缺血是一个复杂的损伤级联反应，其中氧化应激损伤起了关键的作用。氧化应激产生的氧化产物不但可以直接攻击大分子物质如脂肪、蛋白、核酸，使之发生过氧化，导致细胞坏死，还可以通过间接介导线粒体途径、DNA修复酶及转录因子等导致细胞凋亡。通过应用抗氧化酶(如超氧化物歧化酶等)，可以有效防止氧化损伤、阻断氧化应激在脑缺血后的信号传导和损伤。本就氧化应激在脑缺血损伤中的作用机制作一综述。     

不同产地丹参脂溶性成分对H9C2心肌细胞缺氧缺糖损伤保护作用的差异

通过HPLC谱图比较不同产地丹参脂溶性成分含量的差异,采用MTT染色法测定缺氧、缺糖1、2、3 h后H9C2心肌细胞的成活率以建立缺氧缺糖模型组,以低、中、高剂量的丹参脂溶性成分加入模型组细胞,观察细胞的状态确定加药浓度。检测各组的乳酸脱氢酶（LDH）含量、总抗氧化活力（T AC）和细胞存活率（SR）,以此作为考察丹参脂溶性成分保护作用差异的指标。结果表明,缺氧缺糖组以及不同产地丹参脂溶性成分治疗各组的SR与正常对照组相比有显著性差异（P＜0.05）,不同产地丹参脂溶性成分治疗各组的SR与缺氧缺糖组相比有显著性差异（P＜0.05）。缺氧缺糖组以及不同产地丹参脂溶性成分治疗各组的LDH与正常对照组相比有显著性差异（P＜0.05）,不同产地丹参脂溶性成分各组的LDH含量与缺氧缺糖组相比有显著性差异（P＜0.05）。缺氧缺糖组以及不同产地丹参脂溶性成分各组的T AC与正常对照组相比有显著性差异（P＜0.05）,不同产地丹参脂溶性成分各组的T AC与缺氧缺糖组相比有显著性差异（P＜0.05）。丹参脂溶性成分明显减少心肌细胞缺氧缺糖损伤后LDH的溢出,提高了心肌细胞的T AC和SR,其对缺氧缺糖损伤后心肌细胞确实有修复保护作用,不同产地丹参中脂溶性成分对心肌细胞缺氧缺糖保护作用确实存在药效差别。     

Effect of Calcium on Spontaneous Quantal Transmitter Secretion from ACh-Loaded Myocytes

Introduction Transmitter secretion requires specialized secretory or- ganelles, the synaptic vesicles, for the packaging, stor- age, and exocytotic release of the transmitters[1,2]. The neurotransmitter acetylcholine (ACh) is released at the neuromuscular…     

Structural snapshots along the reaction pathway of ferredoxin-thioredoxin reductase

Oxygen-evolving photosynthetic organisms regulate carbon metabolism through a light-dependent redox signalling pathway. Electrons are shuttled from photosystem I by means of ferredoxin (Fdx) to ferredoxin-thioredoxin reductase (FTR), which catalyses the two-electron-reduction of chloroplast thioredoxins (Trxs). These modify target enzyme activities by reduction, regulating carbon flow. FTR is unique in its use of a [4Fe-4S] cluster and a proximal disulphide bridge in the conversion of a light signal into a thiol signal. We determined the structures of FTR in both its one- and its two-electron-reduced intermediate states and of four complexes in the pathway, including the ternary Fdx-FTR-Trx complex. Here we show that, in the first complex (Fdx-FTR) of the pathway, the Fdx [2Fe-2S] cluster is positioned suitably for electron transfer to the FTR [4Fe-4S] centre. After the transfer of one electron, an intermediate is formed in which one sulphur atom of the FTR active site is free to attack a disulphide bridge in Trx and the other sulphur atom forms a fifth ligand for an iron atom in the FTR [4Fe-4S] centre--a unique structure in biology. Fdx then delivers a second electron that cleaves the FTR-Trx heterodisulphide bond, which occurs in the Fdx-FTR-Trx complex. In this structure, the redox centres of the three proteins are aligned to maximize the efficiency of electron transfer from the Fdx [2Fe-2S] cluster to the active-site disulphide of Trxs. These results provide a structural framework for understanding the mechanism of disulphide reduction by an iron-sulphur enzyme and describe previously unknown interaction networks for both Fdx and Trx (refs 4-6).     

Probing the chemistry of thioredoxin catalysis with force

Thioredoxins are enzymes that catalyse disulphide bond reduction in all living organisms. Although catalysis is thought to proceed through a substitution nucleophilic bimolecular (S(N)2) reaction, the role of the enzyme in modulating this chemical reaction is unknown. Here, using single-molecule force-clamp spectroscopy, we investigate the catalytic mechanism of Escherichia coli thioredoxin (Trx). We applied mechanical force in the range of 25-600 pN to a disulphide bond substrate and monitored the reduction of these bonds by individual enzymes. We detected two alternative forms of the catalytic reaction, the first requiring a reorientation of the substrate disulphide bond, causing a shortening of the substrate polypeptide by 0.79 +/- 0.09 A (+/- s.e.m.), and the second elongating the substrate disulphide bond by 0.17 +/- 0.02 A (+/- s.e.m.). These results support the view that the Trx active site regulates the geometry of the participating sulphur atoms with sub-?ngstr?m precision to achieve efficient catalysis. Our results indicate that substrate conformational changes may be important in the regulation of Trx activity under conditions of oxidative stress and mechanical injury, such as those experienced in cardiovascular disease. Furthermore, single-molecule atomic force microscopy techniques, as shown here, can probe dynamic rearrangements within an enzyme's active site during catalysis that cannot be resolved with any other current structural biological technique.     

活性氧双向生物学效应和机制

指出了活性氧（ROS）是普遍存在于有氧代谢中的产物,其化学性质极为活跃,有关ROS对人体的危害已逐渐得到公认.然而,越来越多的研究提示,一直被认为是人类疾病元凶的ROS对机体和细胞也有有益的一面.综述了ROS的研究进展,揭示了ROS通过调节离子通道、受体、酶以及转录因子的活性和改变细胞氧化还原状态,进而参与细胞的正常生理过程（细胞的增殖、分化和凋亡）,从而讨论了ROS的双向生物学效应和机制.     

S-glutathionylation uncouples eNOS and regulates its cellular and vascular function

Endothelial nitric oxide synthase (eNOS) is critical in the regulation of vascular function, and can generate both nitric oxide (NO) and superoxide (O(2)(?-)), which are key mediators of cellular signalling. In the presence of Ca(2+)/calmodulin, eNOS produces NO, endothelial-derived relaxing factor, from l-arginine (l-Arg) by means of electron transfer from NADPH through a flavin containing reductase domain to oxygen bound at the haem of an oxygenase domain, which also contains binding sites for tetrahydrobiopterin (BH(4)) and l-Arg. In the absence of BH(4), NO synthesis is abrogated and instead O(2)(?-) is generated. While NOS dysfunction occurs in diseases with redox stress, BH(4) repletion only partly restores NOS activity and NOS-dependent vasodilation. This suggests that there is an as yet unidentified redox-regulated mechanism controlling NOS function. Protein thiols can undergo S-glutathionylation, a reversible protein modification involved in cellular signalling and adaptation. Under oxidative stress, S-glutathionylation occurs through thiol-disulphide exchange with oxidized glutathione or reaction of oxidant-induced protein thiyl radicals with reduced glutathione. Cysteine residues are critical for the maintenance of eNOS function; we therefore speculated that oxidative stress could alter eNOS activity through S-glutathionylation. Here we show that S-glutathionylation of eNOS reversibly decreases NOS activity with an increase in O(2)(?-) generation primarily from the reductase, in which two highly conserved cysteine residues are identified as sites of S-glutathionylation and found to be critical for redox-regulation of eNOS function. We show that eNOS S-glutathionylation in endothelial cells, with loss of NO and gain of O(2)(?-) generation, is associated with impaired endothelium-dependent vasodilation. In hypertensive vessels, eNOS S-glutathionylation is increased with impaired endothelium-dependent vasodilation that is restored by thiol-specific reducing agents, which reverse this S-glutathionylation. Thus, S-glutathionylation of eNOS is a pivotal switch providing redox regulation of cellular signalling, endothelial function and vascular tone.     

白茅生长及抗氧化酶系统对镉胁迫的生理响应

通过盆栽实验研究了重金属Cd胁迫对白茅幼苗生理生态及抗氧化酶系统的影响.结果表明,镉胁迫对白茅幼苗叶片可溶性蛋白含量、叶片色素含量、根茎生长产生抑制,但一定浓度的重金属镉(≤10 mg/kg)对白茅生长有促进作用.丙二醛(MDA)含量随着Cd处理浓度的升高呈现逐渐升高的趋势.白茅幼苗叶片抗氧化酶系统受到Cd胁迫而失衡,...     

Molecular mechanism of dehydrin in response to environmental stress in plant

Dehydrins, known as the D-11 subgroup of late embryogenesis abundant (LEA) protein, are an immunologically distinct family of proteins, which typically accumulate in desiccation-tolerant seed embryo or in vegetative tissues in response to various environmental stresses such as drought, salinity and freezing. The existence of conservative sequences designated as K, S, and Y segments is a structural feature of dehydrins, and the K segment found in all dehydrins represents a highly conserved 15 amino acid motif (EKKGIMDKIKEKLPG) and forms an amphiphilicα-helix. According to the arrangement of these domains and clustering analysis, dehydrins are subdivided into 5 subtypes: YnSK, Kn, KnS, SKn and YnK. Different types of dehydrins are induced by different environmental stress in plants. Study results showed that dehydrins might play important protective roles under abiotic stress via a number of different mechanisms, including improving or protecting enzyme activities by the cryoprotective activity in responding to freeze/thaw or dehydration; stabilizing vesicles or other endomembrane structures by function as the membrane stabilizer during freeze induced dehydration, and preventing the membrane system from the oxidative damage induced by reactive oxygen radicals as the radical scavenger. Here, the gene expression and molecular mechanisms of dehydrin in response to stress in plants are discussed.