Co(C_6H_9N_3O_2)_2Cl_2对小麦种子萌发与幼苗生长的影响

以冬小麦为实验材料 ,研究了三种不同浓度的Co(C6H9N3 O2 ) 2 Cl2 对冬小麦种子萌发和苗期生长的影响。结果表明 :不同浓度的Co(C6H9N3 O2 ) 2 Cl2 均具有生物活性 ,它们对小麦的发芽势、生长势、发芽率、种子萌发过程中淀粉酶活力、根系发育以及生物量均有明显的生理作用。     

H2O2参与AM真菌与烟草共生过程

以烟草((Nicotiana tabacum,品种CF90NF)为寄主,苗期接种丛枝菌根(AM)真菌摩西球囊霉(Glomus mosseae,G.m),测定G.m与烟草共生过程中烟草根部H2O2含量以及多胺氧化酶(PAO)和过氧化物酶(POD)活性;研究外源H2O2对G.m侵染烟草的影响以及H2O2清除剂和合成抑制剂对烟草侧根H2O2含量及烟草侧根和菌丝中H2O2荧光强度的影响,以探究H2O2在AM真菌侵染烟草过程中的作用。结果表明,接种G.m 20d后烟草侧根中出现H2O2含量的猝发,一定浓度的外源H2O2促进G.m对烟草的侵染,而H2O2清除剂抗坏血酸(AsA)显著削弱烟草侧根和菌丝中的H2O2荧光强度,降低G.m对烟草的侵染率,表明H2O2参与G.m与烟草共生过程;在G.m与烟草共生过程中,PAO和POD活性显著升高,PAO抑制剂二氨基十二烷(DADD)和POD抑制剂水杨羟肟酸(SHAM)显著降低烟草侧根中H2O2荧光强度,对菌丝中H2O2荧光强度无显著影响,表明烟草根部和G.m均可产生H2O2,PAO和POD参与烟草侧根中H2O2的合成,菌丝中可能存在其他来源的H2O2。     

外源H2O2对盐胁迫下小麦幼苗生理指标的影响

以‘郑麦-004’小麦幼苗为供试材料,采用Hoagland营养液培养方法,通过添加H2O2的清除剂过氧化氢酶(CAT)和抗坏血酸(ASA),研究0.05μmol/L外源H2O2处理对150mmol/L NaCl胁迫下小麦幼苗生长和抗氧化系统活性的影响,探讨低浓度外源H2O2对盐胁迫下小麦幼苗伤害的防护作用及其生理机制。结果显示:外源H2O2能缓解盐胁迫对小麦幼苗生长的抑制效应,降低丙二醛(MDA)含量和超氧自由基(O2.-)的产生速率,使小麦幼苗的株高、根长和干重均显著增加,并能提高超氧化物歧化酶(SOD)、过氧化物酶(POD)、CAT、抗坏血酸氧化酶(APX)等保护酶活性和抗氧化物质谷胱甘肽(GSH)的含量;而H2O2清除剂(CAT和AsA)能够逆转外源H2O2对盐胁迫下小麦幼苗生长的促进作用。研究表明,低浓度外源H2O2处理能促进小麦幼苗中的酶类和非酶类抗氧化剂的产生,减少脂质过氧化物的含量,提高小麦幼苗的耐盐性。     

Ce3+对Cu2+胁迫下菹草叶片Cu毒害的缓解效应研究

在6种不同浓度的铈(C e3 )对0.1 m g.L-1的Cu2 毒害下,研究了菹草叶片中保护酶SOD、POD、CAT的活性,活性氧H2O2,膜脂过氧化产物M DA含量及叶绿素含量等的变化及影响.结果表明,在9~12 d之内,7.5 m g.L-1以下的C e3 可以增强SOD、CAT、POD活性,降低M DA的含量,提高叶片中叶绿素和可溶性蛋白含量,从而减轻Cu2 对菹草植物体的伤害.而随着C e3 作用时间的延长和浓度的增大,C e3 的缓解作用不断减弱,C e3 和Cu2 产生协同效应,加重毒害.本实验结果认为,5~7.5 m g.L-1的C e3 缓解菹草叶片Cu2 毒害效果最好.     

CO2浓度升高与硝化抑制剂对冬小麦田间N2O排放量的影响

以冬小麦中麦175为供试品种,利用农田开放式CO_2浓度增高(FACE)系统,研究未来大气高CO_2浓度对冬小麦田间N_2O排放的影响,以及施用硝化抑制剂(2-氯-6-三氯甲基吡啶)是否可以起到抑制冬小麦田间N_2O的排放量升高的潜能。试验结果表明:CO_2浓度升高显著提高冬小麦田间N2O的排放增幅达到67.6%,追肥灌溉后小麦田N_2O排放量较大,随着冬小麦生育进程的推进N_2O的排放量逐渐减少,硝化抑制剂对中麦175田间N_2O排放量的影响并不明显。因此,在未来高CO_2浓度环境条件下,可以通过采取相应的耕作制度和栽培技术措施等来降低冬小麦田N_2O的排放量。试验结果对冬小麦田间是否选择施用2-氯-6-三氯甲基吡啶来控制N_2O的排放起到一定的参考作用。     

油桃花芽破眠过程中H2O2代谢与Ca2+转运的关系

利用化学测定法分析高温、单氰胺和TDZ 3种破眠处理对"曙光"油桃休眠花芽H2O2代谢的主要影响,利用非损伤微测技术检测H2O2对休眠芽Ca2+转运的影响,研究H2O2在芽休眠解除过程中的调控作用.结果表明:在深休眠时期,高温和单氰胺处理均能诱导芽内H2O2含量升高和过氧化氢酶(CAT)活性降低,并具有显著的破眠作用;TDZ对H2O2含量及CAT、过氧化物酶(POD)活性影响不大,破眠效果较差.休眠花芽原基组织钙通道活跃,对外源Ca2+呈吸收状态.外源H2O2可诱导休眠花芽原基组织Ca2+转运发生变化,低浓度H2O2降低Ca2+吸收速率,高浓度H2O2使组织对Ca2+的转运由吸收转变为释放.这表明休眠芽内H2O2信号和Ca2+信号相关联,通过诱导H2O2积累调控Ca2+信号可能在高温和单氰胺打破休眠的信号转导过程中起重要作用.     

水分胁迫诱导玉米叶片质外体产生H2O2机理

通过组织化学染色、电镜观察、酶活性分析对水分胁迫诱导玉米叶片质外体产生H2O2进行了研究。结果表明:水分胁迫能够诱导玉米叶片内源ABA的积累,ABA参与了水分胁迫诱导的玉米叶片H2O2的产生,质膜NADPH氧化酶、细胞壁过氧化物酶(POD)以及质外体多胺氧化酶(PAO)是水分胁迫诱导玉米细胞在质外体产生H2O2的来源,其中质膜NADPH氧化酶是主要来源;内源ABA的积累参与了水分胁迫激活的质膜NADPH氧化酶、细胞壁POD和质外体PAO活性的提高。研究认为,水分胁迫诱导玉米细胞在质外体产生H2O2可能是由于水分胁迫下内源ABA的积累通过激活质膜NADPH氧化酶、细胞壁POD以及质外体PAO的活性而实现的。     

大气CO2浓度倍增和施氮对冬小麦光合及叶绿素荧光特性的影响

采用开顶式气室,通过土培盆栽实验研究了不同大气CO2浓度(背景空气浓度375μmol·mol-1和倍增浓度750μmol·mol-1)和氮素水平(不施氮和施氮0.25 g/kg)下两个冬小麦品种(小偃6号和小偃22)主要生育期(拔节、孕穗、扬花、灌浆期)叶片叶绿素含量和荧光动力学参数的变化.结果显示,与背景CO2浓度相比,在不施氮条件下大气CO2浓度倍增处理的小麦叶片出现明显的光合下调现象,而施氮时变化不明显;同时,CO2浓度倍增后小麦各主要生育期叶片叶绿素含量均有不同程度地下降,荧光参数初始荧光(F0)值明显提高,最大荧光(Fm)、可变荧光(Fv)、最大光能转换效率(Fv/Fm)和PSⅡ潜在活性(Fv/F0)值均显著降低.施氮可提高冬小麦各个时期叶片叶绿素含量、Fm、Fv、和Fv/F0值,降低F0值;不施氮条件下,大气CO2浓度倍增对冬小麦各主要生育时期叶绿素含量和荧光参数的影响明显,而施氮后影响微弱.研究表明,大气CO2浓度升高对冬小麦光合速率、叶绿素含量和光系统Ⅱ(PSⅡ)的光合电子传递和潜在活性具有一定抑制作用,通过施氮可以有效地缓解其负面效应.     

GA3对离体蒜苔细胞内含物再分配过程中H2O2代谢的作用

离体蒜苔构成一个完整的细胞内含物再分配系统。25℃条件下,于黑暗中贮存时,苔茎基部细胞内含物转移到顶端珠蒜中,最后苔茎下部枯萎,顶端形成鲜嫩多汁的珠蒜。适当浓度GA3处理苔茎基部可以有效抑制上0述细胞内含物再分配过程。已有研究表明,H2O2由超氧化物歧化酶（SOD）催化产生,被过氧化物酶（POD）和过氧化氢酶（CAT）催化降解;H2O2对生物个体发育具有重要调节作用。本文主要测定GA3对离体蒜苔H2O2代谢的影响,为进一步探讨H2O2在细胞内含物再分配中的作用提供参考。取珠蒜未明显膨大的离体蒜苔为供试材料,采用50μg/mLGA3溶液处理蒜苔基部,用比色法和氧电极法测定珠蒜和苔茎下部H2O2水平和SOD、POD、CAT活性。结果表明：（1）在处理后48h内,珠蒜和苔茎下部H2O2代谢即产生明显差异（Fig.1-4);（2）贮存20d后对照珠蒜明显膨大,而GA3不蒜无显著变化（Table1);（3）GA3处理显著提高了珠蒜H2O2水平和SOD、POD、CAT活性,相反苔茎下部H2O2水平和POD、CAT活性受到显著抑制,而SOD活性提高(Fig.5-8)。GA3处理对珠蒜和苔茎下部H2O2代谢的相反作用可能是其调节细胞内含物再分配的作用机制。     

山黧豆根系对H2O2诱导氧化胁迫的生理应答

以水培7d苗龄的山黧豆幼苗为材料,向水培溶液中施加不同浓度H2O2处理山黧豆幼苗24h,分析山黧豆根系受氧化胁迫的程度与抗氧化系统的应答特征,以揭示山黧豆对氧化胁迫的耐受机制。结果显示:(1)随外源H2O2处理浓度的不断增加,山黧豆幼苗侧根的数目无显著变化,而其根的鲜重则显著降低。(2)同时,根系组织的内源H2O2染色范围和程度显著增高,但根尖区域始终保持较低水平的H2O2;相反,O-·2染色范围和程度明显减少,根尖区域却始终保持较高水平的O-·2。(3)同期根系抗坏血酸(ASC)含量及过氧化氢酶(CAT)、过氧化物酶(POD)与抗坏血酸过氧化物酶(APX)的活性均表现出了先升高后降低的趋势,而超氧化物歧化酶(SOD)一直表现为持续上升的趋势。研究表明,在外源H2O2胁迫条件下,山黧豆根系O-·2的积累可能与其生长和活力呈正相关,而根系H2O2的积累则与其受氧化胁迫程度呈正相关;低浓度的H2O2处理可以提高山黧豆抗氧化系统对体内活性氧的清除能力。     

氧化苦参碱对H2O2诱导的L6成肌细胞凋亡的影响

研究氧化苦参碱对L₆大鼠成肌细胞H<>sub>2O₂凋亡的影响．采用过氧化氢损伤L₆大鼠成肌细胞的方法,建立L₆大鼠成肌细胞H₂O₂凋亡模型．使用剂量为0.3,0.15,0.75 g/L的氧化苦参碱处理细胞．应用MTT法统计存活率和流式细胞仪检测细胞周期及凋亡率,用DAPI荧光染色、HE染色以及Bax和Bcl-2抗体鉴定损伤程度,Western blot检测蛋白质差异．结果表明,H₂O₂损伤的成肌细胞存活率降低,凋亡率增加．各种剂量氧化苦参碱能提高成肌细胞的存活率,促使Bcl-2增高,Bax降低．对成肌细胞的保护程度随氧化苦参碱剂量增加而增强,在剂量为0.3 g/L时,效果显著,其次是0.15、0.75 g/L的氧化苦参碱．其生理生化机制是氧化苦参碱保护₂O₂通过NFκB信号通路造成的大鼠成肌细胞凋亡模型．结果显示,氧化苦参碱具有作为新的抗氧化药物的潜力．     

Relationship between C2H2 reduction, H2 evolution and 15N2 fixation in root nodules of pea (Pisum sativum)

The quantitative relationship between C₂H₂ reduction, H₂ evolution and ¹⁵N₂ fixation was investigated in excised root nodules from pea plants ( Pisum sativum L. cv. Bodil) grown under controlled conditions. The C₂H₂/N₂ conversion factor varied from 3.31 to 5.12 between the 32nd and the 67th day after planting. After correction for H₂ evolution in air, the factor (C₂H₂-H₂)/N₂ decreased to values near the theoretical value 3, or in one case to a value significantly ( P < 0.05) below 3. The proportion of the total electron flow through nitrogenase, which is not wasted in H₂ production but used for N₂ reduction, is often stated as the relative efficiency (1-H₂/C₂H₂). This factor varied significantly ( P < 0.05) during the growth period. The actual allocation of electrons to H₂ and N₂, expressed as the H₂/N₂ ratio, was independent of plant age, however. This discrepancy and the observation that the (C₂H₂-H₂)/N₂ conversion factor tended to be lower than 3, suggests that the C₂H₂reduction assay underestimates the total electron flow through nitrogenase.     

Effect of H2 evolution on 15N2 fixation, C2H2 reduction and relative efficiency of leguminous symbionts

The (C₂H₄+ H_2(C2H₂))/¹⁵N₂ ratios of 15 clover- Rhizobium symbionts. soybean, and black medick symbionts were measured. Relative efficiency based on the C2H4 production and on ¹⁵N₂ incorporation were compared, and in most symbionts there was little difference between the two measures of relative efficiency. Total measurable electron flux through nitrogenase during acetylene reduction and ¹⁵N₂ incorporation were nearly equal for most symbionts studied. The relative efficiency and the (C₂H₄+ H_2(C2H₂))/¹⁵N₂ ratio showed an inverse correlation. Use of this ratio appears preferable to use of the ratio of C2H2 reduction/N₂ reduction. Some evolution of H₂ was observed in the presence of C₂H₂.     

Crystal structures of MoCl2(O)(O2)(OPMePh2)2 and mixtures of MoCl2(O2)(OPPh3)2 and MoCl2(O)(O2)(OPPh3)2: allylic alcohol isomerization studies using MoCl2(O)(O2)(OPMePh2)2

Adding one equivalent of H₂O₂ to compounds of stoichiometry MoCl₂(O)₂(OPR₃)₂, OPR₃ = OPMePh₂ or OPPh₃, leads to the formation of oxo-peroxo compounds MoCl₂(O)(O₂)(OPR₃)₂. The compound MoCl₂(O)(O₂)(OPMePh₂)₂ crystallized with an unequal disorder, 63%:37%, between the oxo and peroxo ligands, as verified by single-crystal X-ray diffractometry, and can be isolated in reasonable yields. MoCl₂(O)(O₂)(OPPh₃)₂, was not isolated in pure form, co-crystallized with MoCl₂(O)₂(OPPh₃)₂ in two ratios, 18%:82% and 12%:88%, respectively, and did not contain any disorder in the arrangement of the oxo and peroxo groups. These complexes accomplish the isomerization of various allylic alcohols. A mechanism of this reaction has been constructed based on ¹⁸O isotopic studies and involves exchange between the alcohol and metal bonded O atoms.     

P2X2, P2X2–2 and P2X5 receptor subunit expression and function in rat thoracolumbar sympathetic neurons

The present study investigated the pharmacological properties of excitatory P2X receptors and P2X(2) and P2X(5) receptor subunit expression in rat-cultured thoracolumbar sympathetic neurons. In patch-clamp recordings, ATP (3-1000 microM; applied for 1 s) induced inward currents in a concentration-dependent manner. Pyridoxal-phosphate-6-azophenyl-2',4'-disulfonate (PPADS; 30 microM) counteracted the ATP response. In contrast to ATP, alpha,beta-meATP (30 microM; for 1 s) was virtually ineffective. Prolonged application of ATP (100 microM; 10 s) induced receptor desensitization in a significant proportion of sympathetic neurons in a manner typical for P2X(2-2) splice variant-mediated responses. Using single-cell RT-PCR, P2X(2), P2X(2-2) and P2X(5) mRNA expression was detectable in individual tyrosine hydroxylase-positive neurons; coexpression of both P2X(2) isoforms was not observed. Laser scanning microscopy revealed both P2X(2) and P2X(5) immunoreactivity in virtually every TH-positive neuron. P2X(2) immunoreactivity was largely distributed over the cell body, whereas P2X(5) immunoreactivity was most distinctly located close to the nucleus. In summary, the present study demonstrates the expression of P2X(2), P2X(2-2) and P2X(5) receptor subunits in rat thoracolumbar neurons. The functional data in conjunction with a preferential membranous localization of P2X(2)/P2X(2-2) compared with P2X(5) suggest that the excitatory P2X responses are mediated by P2X(2) and P2X(2-2) receptors. Apparently there exist two types of P2X(2) receptor-bearing sympathetic neurons: one major population expressing the unspliced isoform and another minor population expressing the P2X(2-2) splice variant.     

血红蛋白A2现象发生机制的研究——“红细胞HbA2”为HbA2与HbA的结合产物

为了弄清血红蛋白A₂现象的发生机制,我们对“红细胞HbA₂”的化学组成进行了分析。“红细胞HbA₂”的双向电泳结果表明,它含有两种血红蛋白成分:一种相当于HbA,另一种很可能是溶血液HbA₂。其单向二次电泳结果也证明,它是由溶血液HbA₂和HbA所组成。结果初步说明,盘红细胞中HbA₂可能与HbA结合存在。两者可能有相互作用,也许这是产生血红蛋白A₂现象的原因。     

Study on the heterogeneous degradation of chitosan with H2O2 catalyzed by a new supermolecular assembly crystal: [C6H8N2]6H3[PW12O40]·2H2O

A new supermolecular assembly crystal, [C₆H₈N₂]₆H₃[PW₁₂O₄₀]·2H₂O (DMB-PWA), was synthesized with phosphotungstic acid (PWA) and 1,2-diaminobenzene (DMB) under hydrothermal conditions and was characterized by Fourier-transform infrared spectra (FTIR) and single-crystal X-ray diffraction analysis. DMB-PWA could effectively catalyze oxidative degradation of chitosan with H₂O₂ in the heterogeneous phase. The optimum degradation conditions were determined by orthogonal tests as follows: amount of chitosan 1.00 g, 30% (wt %); H₂O₂, 3.0 mL; dosage of catalyst, 0.06 g; reaction temperature, 85 °C; and reaction time, 30 min. The water-soluble chitosan with a viscosity-average molecular weight (M_v) of 4900 was obtained under the optimum degradation conditions and was characterized by FTIR, ultraviolet-visible diffuse reflection spectra (UV-vis DRS), and X-ray powder diffraction analysis.     

Generation of H2O2 in Brain Mitochondria

Generation of H2O2 by rat brain mitochondria using succinate and glycerol-1-phosphate as substrates has been demonstrated. Earlier workers were unable to detect this activity in sucrose-Tris buffer. We found that this was due to a lag in the expression of activity in sucrose medium. Using phosphate buffer (50 mM), good rates are now obtained. Generation of H2O2 by rat brain mitochondria required the presence of antimycin A and was dependent on the substrates succinate and glycerol-1-phosphate. Low rates were obtained with NAD+-linked substrates and none with choline, glutamate, and NADH. The Km and Vmax values for H2O2 generation were considerably lower than the corresponding values for the respective dehydrogenase activity, measured by dye reduction. Oxygen-radical scavengers inhibited H2O2 generation, suggesting oxygen radical involvement. Depletion of ubiquinone from mitochondria resulted in loss of H2O2 generation. Reconstitution of such depleted particles with ubiquinone restored the capacity to generate H2O2 in a concentration-dependent manner. Levels of H2O2 production were found to be maximal in cerebellum. Brain mitochondria from rabbit, hamster, mouse, and guinea pig also have the capacity to generate H2O2 on oxidation of glycerol-1-phosphate.     

Glucose biosensor based on the room-temperature phosphorescence of TiO2/SiO2 nanocomposite

The direct immobilization of glucose oxidase (GOD) on TiO₂/SiO₂ nanocomposite and its application as glucose biosensor were investigated. The room-temperature phosphorescence of TiO₂/SiO₂ nanocomposite can be quenched by hydrogen peroxide (H₂O₂). The detection of glucose may be accomplished by monitoring the formation of hydrogen peroxide which generated in the oxidation process of glucose with the catalysis of GOD. To our surprise, by using a 96-hole polyporous plate accessory of fluorescence spectrophotometer, the biosensor exhibits excellent linear response to glucose concentrations ranging from 1.0 × 10⁻⁹ to 1.0 × 10⁻² M with a detection limit of 1.2 × 10⁻¹⁰ M. The TiO₂/SiO₂ nanocomposite can be used as both supporting material and signal transducer. The phosphorescence intensity and color of the biosensor change obviously and even could be observed with naked eyes by continuous addition of glucose. Based on the room-temperature phosphorescence of TiO₂/SiO₂ nanocomposite, a new method of solid substrate-room-temperature phosphorimetry (SS-RTP) for glucose determination is proposed. A glucose biosensor was fabricated with wide determination concentration range, low detection limit, high sensitivity, and fast response time. And the biosensor has been successfully applied to the determination of glucose in human blood serum. The coacervation of GOD enzyme and its interaction with TiO₂/SiO₂ nanocomposite enlarge the surface area and enhance the chemical stability of GOD. The nice biocompatibility, large surface area, good chemical stability and nontoxicity of the TiO₂/SiO₂ nanocomposite have made this material suitable for functioning as biosensor.