NO和NADPH-黄递酶在绿豆下胚轴不定根发生和发育过程中的变化

研究了一氧化氮(NO)供体普钠(SNP)、一氧化氮清除剂C-PTIO和一氧化氮合酶(NOS)抑制L-NAME对绿豆(Vigna radiataL.)下胚轴插条生根的影响.并对不定根生期间手条基部NO 和NADPH-黄递酶的时空变化进行了检测.所试浓度SNP均明显促进下胚轴不根发生.分别插条切取后24h和36h于其基部维管束之间检测到NADPH-黄递酶(NOS标记酶)阳性反应和NO荧光,根原基也于48h在相同位置出现,并于60h进一步伸长.48~60h期间,NADPH、黄递的阳性反应及NO荧光有增强趋势,并主要分布在不定根分生组织中.L-NAME既减弱NADPH-黄递酶的阳性反应和NO荧光,也延缓不不定根发生;而c-PTIO对NO荧光及不定根生均有抑制作用.上述结果证明:NO在不定根发生及发育过程中有重要作用,而且此过程中的NO很可能由类似的NOS催化产生.     

脱落酸对绿豆下胚轴不定根发生的影响

以10^-4 mol/L脱落酸(ABA)处理绿豆种子24 h,在幼苗下胚轴长6 cm时,切除根部作为插条,研究ABA对插条不定根发生及插条基部细胞周期时相的影响。结果表明,ABA可促进下胚轴插条不定根发生,增加生根数和生根范围;ABA提高插条基部细胞色氨酸转氨酶、吲哚丙酮酸脱羧酶和吲哚乙醛脱氢酶的比活性,增加吲哚乙酸含量,同时进入细胞周期S期的基部细胞数目增加,促进DNA合成,有利于不定根的发生。     

硝普钠（SNP）对绿豆下胚轴插条生根的影响

研究了SNP对绿豆下胚轴插条生根的影响.结果表明,SNP促进下胚轴插条生根的最适浓度和最佳时间分别为300μmol*L-1和24 h,最适浓度SNP对6 d龄幼苗下胚轴插条生根促进效果最好,对下胚轴插条的生根促进效应显著大于其余插条.同时就SNP、IBA和NAA对不定根发生的影响进行了比较研究.     

Cd胁迫下SA和NO互作对小麦幼苗根生长和叶绿素含量的影响

以"陇春27"号水培小麦幼苗为研究材料，外源添加水杨酸（SA）、一氧化氮（NO）清除剂（carboxy-PTIO，c-PTIO）、NO供体硝普钠（SNP）、硝酸还原酶（NR）抑制剂钨酸盐（Tungstate）及NO合成酶（NOS）抑制剂（L-NAME）进行不同预处理，分析其在镉（Cd）胁迫下根的生长和叶片叶绿素含量的变化，探讨SA和NO互作对小麦幼苗Cd胁迫的缓解机制。结果表明：随着Cd处理时间的延长，小麦幼苗根中SA含量显著降低，NO含量则呈现先增加（6 h和12 h）后减少（24 h和48 h）的趋势；Cd胁迫抑制了小麦幼苗根的生长，减少了叶片叶绿素的含量，而一定浓度的SA或SNP预处理可以缓解Cd胁迫对小麦幼苗根长的抑制作用，增加叶绿素的含量。c-PTIO、L-NAME和Tungstate单独预处理显著抑制了小麦幼苗根的生长，减少了NO的含量，但不影响叶绿素含量。SA400+L-NAME预处理可以缓解Cd胁迫对小麦幼苗根长的抑制作用以及叶绿素和NO含量的减少作用；SA400+c-PTIO或SA400+Tungstate预处理可增加Cd胁迫下叶绿素的含量，但对根的伸长无影响。进一步研究发现，Cd胁迫抑制了NR的活性，而SA400预处理可以使Cd胁迫下NR的活性增强，不同处理对NOS的活性均无影响。综上所述，Cd胁迫导致小麦幼苗根内源SA含量降低和NO含量先升高再降低；外源添加SA或SNP预处理缓解了Cd胁迫对根生长的抑制和叶绿素含量降低的作用；外源SA通过影响NO的产生从而提高小麦幼苗对Cd胁迫的耐受性，最终缓解了Cd对小麦幼苗的毒害作用。     

EDDS对Cd胁迫下三叶鬼针草幼苗NO产生的影响

【摘要】通过室内盆栽试验, 研究了40 mg·kg-1 Cd(CdCl2·2.5 H2O)胁迫下, 不同浓度乙二胺二琥珀酸(EDDS)(0、0.5、1.5、2.5、5.0 mmol·L-1)单施及EDDS与一氧化氮(NO)供体硝普钠(SNP)(0、0.25、0.5、1.0 mmol·L-1)联合施加对三叶鬼针草(Bidens pilosa L.)幼苗应激信号分子NO产生量和一氧化氮合酶(NOS)活性的影响。结果表明: 单施EDDS, 植株不同部位NO生成量随EDDS浓度的升高呈增加趋势, 5.0 mmol·L-1时达到最大; 0.5 mmol·L-1的EDDS可增强根、叶中NOS活性。在探究NO产生较多和NOS活性增强显著的EDDS处理浓度与SNP联合施加的研究中发现, 随SNP浓度的升高, 根中NO生成量先升高后降低, 茎和叶中持续升高; 适宜浓度的SNP可进一步增强植株体内NOS活性。EDDS诱导NO的生成会被硝酸还原酶(NR)抑制剂(NaN3)和NOS抑制剂(L-NAME)抑制, 对EDDS处理下NOS活性影响较小。NO清除剂(c-PTIO)能有效清除部分NO, 增强根和叶中NOS活性。因此, 在Cd胁迫下, 适宜浓度的EDDS单施及与SNP联合施加都会增加三叶鬼针草幼苗体内NO产生量。     

大豆甙元磺酸钠对应激性胃粘膜损伤的影响及其机制探讨

目的：观察大豆甙元磺酸钠对力竭应激性渍疡的影响,探讨其可能的作用途径。方法：采用小鼠力竭性游泳,计数胃部溃疡点数建立应激溃疡模型,腹腔注射不同剂量的大豆甙元磺酸钠及一氧化氮合酶（NOS）抑制剂（L-NAME）并通过NADPH-黄递酶组织化学法检测胃壁NOS阳性神经元的变化。结果：大豆甙元磺酸钠具有保护胃粘膜的作用,且呈剂量效应;L-NAME可防止应激引起的胃粘膜损伤,L-NAME与有效剂量的大豆甙元磺酸钠联合使用后,大豆甙元磺酸钠对胃粘膜的保护作用明显增强;正常及应激小鼠胃壁NOS神经节数目基本不变,大豆甙元磺酸钠对正常小鼠胃壁NOS神经元影响不明显,而对应激小鼠胃壁单位面积及单个神经节内NOS阳性神经元数目均有显著降低作用。结论：应激时NO升高可导致溃疡,大豆甙元磺酸钠能够保护胃粘膜,其作用是通过抑制应激状态下NOS的升高,限制应激状态下NO过度升高,起到保护胃粘膜的作用。     

一氧化氮在乙烯诱导蚕豆气孔关闭中的作用

以蚕豆为材料研究了一氧化氮(nitric oxide,NO)和乙烯对气孔运动的影响。结果表明,10μmol/L的NO供体硝普钠(sodium nitroprusside,SNP)以及0.04%的乙烯能明显诱导蚕豆气孔关闭,并且二者共同处理后,能够增强其促进气孔关闭的作用。乙烯合成抑制剂AVG可以减弱NO诱导气孔关闭的程度,NO清除剂c-PTIO和NR抑制剂NaN3也可减弱乙烯诱导气孔关闭的程度,而一氧化氮合酶(nitric oxide synthase,NOS)抑制剂L-NAME对乙烯诱导气孔关闭的作用不明显。推测,在调控蚕豆气孔关闭过程中,NO可能主要通过NR途径参与乙烯调控气孔关闭过程。     

NO对盐胁迫下苜蓿根系生长抑制及氧化损伤的缓解效应

以"甘农4号"苜蓿品种为材料,采用水培法,用NO供体硝普钠(SNP)、硝普钠类似物亚铁氰化钠(不产生NO)、NO特异清除剂c-PTIO、一氧化氮合酶(NOS)活性抑制剂N-硝基-L-精氨酸甲脂(L-NAME)、硝酸还原酶(NR)活性抑制剂钨酸盐处理苜蓿植株,研究NO对盐胁迫下苜蓿幼苗根系生长、根系活力、根系中渗透调节物质、膜脂过氧化、活性氧含量及抗氧化酶活性等的影响,探讨NO调控苜蓿幼苗根系耐盐性的生理机制。结果表明:盐胁迫下SNP处理提高了根系活力,促进了苜蓿幼苗根系生长,降低游离脯氨酸含量,促进可溶性蛋白含量增加;增强超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、愈创木酚过氧化物酶(GPX)、抗坏血酸过氧化物酶(APX)和谷胱甘肽还原酶(GR)活性,提高还原型抗坏血酸(As A)和还原型谷胱甘肽(GSH)含量,降低过氧化氢(H2O2)、羟自由基(OH·)含量、超氧阴离子(O·-2)产生速率和膜脂过氧化产物丙二醛(MDA)含量;同时,SNP处理显著促进了苜蓿幼苗根系内源NO的积累。NO供体SNP的类似物亚铁氰化钠对盐胁迫下苜蓿根系各项生理生化指标无明显影响;盐胁迫下添加c-PTIO、L-NAME和钨酸盐进一步降低了苜蓿幼苗根系活力和根系生长,抑制了根系抗氧化系统活性,加剧了根系膜脂过氧化作用,降低了内源NO积累,添加SNP则能缓解该抑制效应;表明外源SNP处理能明显缓解盐胁迫对苜蓿幼苗根系生长的抑制和氧化损伤,且通过NOS和NR途径产生的内源NO也可能在苜蓿根系适应盐胁迫的调节中起关键作用;该研究结果为苜蓿耐盐机制及NO在苜蓿耐盐育种、化学调控和盐碱地栽培利用等提供了理论依据。     

正弦波电磁场激活一氧化氮信号通路促进大鼠成骨细胞成熟与矿化

研究正弦波电磁场(SEMF)促进成骨细胞成熟矿化是否与一氧化氮(NO)信号通路相关.首先检测成骨细胞经正弦电磁场作用0h、0.5h、1h、1.5h、2h、2.5h、3h、3.5h和4h后一氧化氮合酶(NOS)的活性,以探明电磁场是否影响NO的合成;其次,在细胞培养液中加入NOS的阻断剂L-NAME以阻断NO信号通路,观察电磁场促进骨形成作用是否受到影响.结果发现,经正弦波电磁场处理后,NOS活性升高,在0.5h达到峰值,与空白对照组差异极显著(P<0.01),Osterix基因的表达量、碱性磷酸酶活性和钙化结节数等均显著高于对照组.L-NAME组各项指标均低于空白对照组,SEMF+L-NAME组则略高于空白对照组而低于SEMF组.以上结果表明SEMF促进成骨细胞成熟矿化过程中NO信号通路被激活,如该通路被抑制,则SEMF的促成骨作用被抵消.     

生长素、乙烯和一氧化氮对拟南芥下胚轴插条形成不定根的调节

研究生长素、乙烯和一氧化氮（NO）对拟南芥下胚轴插条形成不定根的调节,以及生长素和乙烯信号转导成员在IAA促进不定根形成中的作用的结果表明：拟南芥切条以IAA和硝普钠（N0供体）单独处理7d后的不定根形成均受到促进,其中以50μmol·L^-1 IAAμmol·L^-1 SNP的促进作用为最强,乙烯的促进作用不明显;生长素运输和信号转导以及乙烯信号转导相关突变体对IAA促进生根作用的敏感性比野生型有所下降,特别是IAA14功能获得型的突变体。IAA和NO在促进不定根形成中有协同效应。     

The dynamic distribution of NO and NADPH–diaphorase activity during IBA-induced adventitious root formation

Nitric oxide (NO) is a multifunctional molecule involved in numerous physiological processes in plants. In this study, we investigate the spatiotemporal changes in NO levels and endogenous NO‐generating system in auxin‐induced adventitious root formation. We demonstrate that NO mediates the auxin response, leading to adventitious root formation. Treatment of explants with the auxin indole‐3‐butyric acid (IBA) plus the NO donor sodium nitroprusside (SNP) together resulted in an increased number of adventitious roots compared with explants treated with SNP or IBA alone. The action of IBA was significantly reduced by the specific NO scavenger, 2‐(4‐carboxyphenyl)‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide (c‐PTIO), and the nitric oxide synthase (NOS, enzyme commission 1.14.13.39) inhibitor, N^G‐nitro‐l ‐arg‐methyl ester (l ‐NAME). Detection of endogenous NO by the specific probe 4,5‐diaminofluorescein diacetate and survey of NADPH–diaphorase activity (commonly employed as a marker for NOS activity) by histochemical staining revealed that during adventitious root formation, NO and NADPH–diaphorase signals were specifically located in the adventitious root primordia in the basal 2‐mm region (as zone I) of both control and IBA‐treated explants. With the development of root primordia, NO and NADPH–diaphorase signals increased gradually and were mainly distributed in the root meristem. Endogenous NO and NADPH–diaphorase activity showed overall similarities in their tissue localization. Distribution of NO and NADPH–diaphorase activity similar to that in zone I were also observed in the basal 2–4‐mm region (zone II) of IBA‐treated explants, but neither NO nor NADPH–diaphorase signals were detected in this region of the control explants. l ‐NAME and c‐PTIO inhibited the formation of adventitious roots induced by IBA and reduced both NADPH–diaphorase staining and NO fluorescence. These results show the dynamic distribution of endogenous NO in the developing root primordia and demonstrate that NO plays a vital role in IBA‐induced adventitious rooting. Also, the production of NO in this process may be catalyzed by a NOS‐like enzyme.     

Role of nitric oxide dependence on nitric oxide synthase-like activity in the water stress signaling of maize seedling

Nitric oxide (NO) has been known as an important signal in plant antioxidative defense but its production and roles in water stress are less known. The present study investigated whether NO dependence on a NO synthase-lika (NOS) activity is involved in the signaling of drought-induced protective responses in maize seedlings. NOS activity, rate of NO release and drought responses were analyzed when NO donor sodium nitroprusside (SNP), NO scavenger c-PTIO (2-(4-carboxyphenyl)-4,4,5,5-tetramathylimidazoline-1-oxyl-3-oxide) and NOS inhibitor L-NAME (NG-nitro-L-arginine methyl ester) were applied to both detached maize leaves and whole plants. Both NOS activity and the rate of NO release increased substantially under dehydration stress. The high NOS activity induced by c-PTIO as NO scavenger and NO accumulation Inhibited by NOS inhibitor L-NAME In dehydration-treated maize seedlings Indicated that most NO production under water deficit stress may be generated from NOS-like activity. After dehydration stress for 3 h, detached maize leaves pretreated with NO donor SNP maintained more water content than that of control leaves pretreated with water. This result was consistent with the decrease in the transpiration rate of SNP-treated leaves subjected to drought treatment for 3 h. Membrane permeability, a cell injury index, was lower in SNP-trested maize leaves under dehydration stress for 4 h when compared with the control leaves. Also, superoxide dismutsse (SOD) activity of SNP combined drought treatment maize leaves was higher than that of drought treatment alone, indicating that exogenous NO treatment alleviated the water loss and oxidative damage of maize leaves under water deficit stress. When c-PTIO as a specific NO scavenger was applied, the effects of applied SNP were overridden. Treatment with L-NAME on leaves also led to higher membrane permeability, higher transpiration rate and lower SOD activities than those of control leaves, indicating that NOS-like activity was involved in the antioxidative defense under water stress. These results suggested that NO dependence on NOS-like activity serves as a signaling component in the induction of protective responses and is associated with drought tolerance in maize seedlings.     

Nia1 and Nia2 are Involved in Exogenous Salicylic Acid-induced Nitric Oxide Generation and Stomatal Closure in Arabidopsis

Phytohormone salicylic acid (SA) plays important roles in plant responses to environmental stress. However, knowledge about the molecular mechanisms for SA affecting the stomatal movements is limited. In this paper, we demonstrated that exogenous SA significantly induced stomatal closure and nitric oxide (NO) generation in Arabidopsis guard cells based on genetic and physiological data. These effects were significantly inhibited by the NO scavenger c-PTIO, NO synthase (NOS) inhibitor L-NAME or nitrate reduc...     

Pharmacological and genetical evidence supporting nitric oxide requirement for 2,4-epibrassinolide regulation of root architecture in Arabidopsis thaliana

Brassinosteroids (BRs) regulate various physiological processes, such as tolerance to stresses and root growth. Recently, a connection was reported between BRs and nitric oxide (NO) in plant responses to abiotic stress. Here we present evidence supporting NO functions in BR signaling during root growth process. Arabidopsis seedlings treated with BR 24-epibrassinolide (BL) show increased lateral roots (LR) density, inhibition of primary root (PR) elongation and NO accumulation. Similar effects were observed adding the NO donor GSNO to BR-receptor mutant bri1-1. Furthermore, BL-induced responses in the root were abolished by the specific NO scavenger c-PTIO. The activities of nitrate reductase (NR) and nitric oxide synthase (NOS)-like, two NO generating enzymes were involved in BR signaling. These results demonstrate that BR increases the NO concentration in root cells, which is required for BR-induced changes in root architecture.     

Activation of the mitogen-activated protein kinase cascade through nitric oxide synthesis as a mechanism of neuritogenic effect of genipin in PC12h cells

Prominent neurite outgrowth induced by genipin, a plant-derived iridoid, was substantially inhibited by addition of NG-nitro-L-arginine methyl ester (L-NAME), a nitric oxide (NO) synthase (NOS) inhibitor, and carboxy-PTIO, an NO scavenger, in PC12h cells. Increases of the NADPH-diaphorase activity and neuronal and inducible NOS proteins in cells preceded the neurite outgrowth after addition of genipin to medium. NO donors could induce the neurite outgrowth dose-dependently in the cells. On the other hand, an inhibitor of soluble guanylate cyclase (SGC), which is known to be a stimulatory target of NO, abolished greatly the genipin-induced neurite outgrowth. Addition of extracellular signal-regulated kinase (ERK) kinase inhibitors could almost completely abolish the neurite induction. L-NAME remarkably depressed genipin-stimulated phosphorylation of ERK-1 and -2. A neuritogenic effect of nerve growth factor (NGF) in PC12h cells was also remarkably inhibited by the NOS inhibitor, NO scavenger and SGC inhibitor. These findings suggest that induced NO production followed by cyclic GMP-mediated stimulation of the mitogen-activated protein kinase (MAPK) cascade is implicated in the neuritogenesis by genipin and NGF in PC12h cells.     

Role of nitric oxide in abscisic acid-induced subcellular antioxidant defense of maize leaves

The sources of nitric oxide (NO) production in response to abscisic acid (ABA) and the role of NO in ABA-induced hydrogen peroxide (H(2)O(2)) accumulation and subcellular antioxidant defense in leaves of maize (Zea mays L.) plants were investigated. ABA induced increases in generation of NO and activity of nitric oxide synthase (NOS) in maize leaves. Such increases were blocked by pretreatment with each of the two NOS inhibitors. Pretreatments with a NO scavenger or NR inhibitors inhibited ABA-induced increase in production of NO, but did not affect the ABA-induced increases in activity of NOS, indicating that ABA-induced NO production originated from sources of NOS and NR. ABA- and H(2)O(2)-induced increases in expression of the antioxidant genes superoxide dismutase 4 (SOD4), cytosolic ascorbate peroxidase (cAPX), and glutathione reductase 1 (GR1) and the activities of the chloroplastic and cytosolic antioxidant enzymes were arrested by pretreatments with the NO scavenger, inhibitors of NOS and NR, indicating that NO is involved in the ABA- and H(2)O(2)-induced subcellular antioxidant defense reactions. On the other hand, NO donor sodium nitroprusside (SNP) reduced accumulation of H(2)O(2) induced by ABA, and c-PTIO reversed the effect of SNP in decreasing the accumulation of H(2)O(2). SNP induced increases in activities of subcellular antioxidant enzymes, and the increases were substantially prevented from occurring by the pretreatment with c-PTIO. These results suggest that ABA induces production of H(2)O(2) and NO, which can up-regulate activities of the subcellular antioxidant enzymes, to prevent overproduction of H(2)O(2) in maize plants. There is a negative feedback loop between NO and H(2)O(2) in ABA signal transduction in maize plants.     

Effect of centrally administered nitric oxide modulators in Brewer's yeast-induced nociception in rats

Possible modulation of Brewer's yeast-induced nociception by centrally (icv) administered nitric oxide (NO) modulators, viz., NO synthase (NOS) inhibitors, NO precursor, donors, scavengers and co-administration of NO donor (SIN-1) with NOS inhibitor (L-NAME) and NO scavenger (Hb) was investigated in rats. Administration of NOS inhibitors and NO scavenger Hb increased the pain threshold capacity significantly, whereas NO donors SIN-1, SNP and NO precursor L-arginine were found to be hyperalgesic. D-arginine, the inactive isomer of L-arginine and methylene blue, inhibitor of soluble guanylate cyclase failed to alter the nociceptive behaviour in rats. Co-administration of SIN-1 with L-NAME and Hb found to increase the nociceptive threshold. The results indicate, that centrally administered NO modulators alter the nociceptive transmission induced by Brewer's yeast in rats.