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1.
ABA诱导蚕豆气孔保卫细胞H2O2的产生   总被引:22,自引:0,他引:22  
以蚕豆叶片下麦皮为材料,将荧光探针HPTS导入蚕豆忆保卫细胞内,利用荧光光谱和激光共聚焦显微技术,检测了ABA诱导蚕豆气孔关闭过程中H2O2的产生。结果表明,ABA和100μmol/L的H2O2可以迅速猝灭HPTS的荧光,CAT几乎可完全阻止9μl0.2mmol/L的ABA引起荧光猝灭。因此,ABA可以诱导气孔保卫细胞产生H2O2,其产生的强度和速度与ABA的浓度直接有关,并且推测:这种H2O2产  相似文献   

2.
孔铁民  靳爱华  翁宾   《微生物学通报》2000,27(5):366-367
2-噻唑丙氨酸是1950年由Reuben G以组氨酸结构类似物首次合成[1],其用途为抗菌剂。近年来将其作为诱变拮抗剂,在生产氨基酸领域有较广的应用[2~5]。 为使国内研究机构开展此项工作,我们合成了2-噻唑 丙氨酸并对其合成方法进行改进。2-噻唑丙氨酸的合 成路线[6、7]如下: 文献报道的合成方法为由2-氨基甲基噻唑制备2- 氯甲基噻唑。但2-氨基甲基噻唑较难制备。因此,我们 设计以2-氨基噻唑为原料,经亚硝化、重氮化合成噻 唑。再与甲醛反应制得2-羟甲基噻唑,氯化后得2-氯甲基噻唑。按文献方法合…  相似文献   

3.
在系统中H2O2与所含有的亚铁离子通过Fenton反应主要生成OH自由基损伤细胞,但H2O2也可损伤细胞膜或细胞。为区分Fenton自由基体与H2O2分别对红细胞膜脂质及蛋白分子相对旋转时间影响机理的不同,分别对体外不同浓度Fenton体系和不同浓度H2O2作用30分钟后,红细胞膜剪切弹性模量μ、细胞表面指数Si、膜蛋白分子τp及脂质分子τl相对旋转时间和它们的化学结构进行了比较分析。结果发现,(  相似文献   

4.
白细胞介素2的中枢作用   总被引:4,自引:0,他引:4  
白细胞介素2(IL-2)不仅是重要的免疫调节因子,而且具有重要的中枢调节作用。业已证实,脑内存在着IL-2和IL-2受体(IL-2R),IL-2能明显地影响神经元和神经胶质细胞的生长,并能作用于下丘脑-垂体-肾上腺轴而影响内分泌,还能对电生理、行为等产生影响。本文简述了IL-2的中枢作用。  相似文献   

5.
UV—B辐射对小麦叶片H2O2代谢的影响   总被引:12,自引:1,他引:11  
研究了温室种植的小麦在0(CK)、8.82kJ/m^2(T1)和12.6kJ/m^2(T2)三种剂量的紫外线B(UV-B)辐射下H2O2含量的变化及其机理。UV-B辐射下H2O2、还原型抗坏血酸(AsA)和还原型谷胱甘肽(GSH)含量增加,抗坏血酸过氧化物酶(APx)和谷胱甘肽不原酶(GR)活性升高,脂肪酸不饱和度指数(IUFA)降低。SDS-PAGE谱图没有质上的差异,但凝胶着色深浅有变化。分析  相似文献   

6.
类胡萝卜素对H_2O_2-NaOCl体系生成的~1O_2的猝灭作用   总被引:22,自引:0,他引:22  
通过H2O2与NaOCl的反应体系产1O2,使用超微弱发光仪在710nm处测量了β胡萝卜素、α生育酚酸酯与抗坏血酸的1O2猝灭能力。结果表明,1O2猝灭能力按发下顺序递减:斑蝥黄素、胭脂树橙、β胡萝卜素、叶黄素、生育酚与抗坏血酸。但是具有较低1O2猝灭常数Kq值的化合物在人体血浆中却以较高水平存在,说明它们在保护机体防御1O2的有害影响上起着同样重要作用  相似文献   

7.
本工作采用分离培养家兔肺内小动脉平滑肌细胞(PASMCs),观察了外源性血小板活化因子(plateletactivatingfactor,PAF)、BN52021(PAF受体拮抗剂)、吲哚美辛、维拉帕米对PASMCs产生血栓素A_2(TxA_2)、前列环素(PGI_2)及对细胞膜Ca~(2+)-ATPase活力的影响。结果表明:(1)基础状态下PASMCs存在花生四烯酸(AA)代谢。(2)外源性PAF通过受体后途径激活环加氧酶促进AA代谢致TXA_2及PGI-2增加,TXA_2/PGI_2比值无明显变化。(3)外源性PAF能直接抑制Ca~(2+)-ATPase活力。(4)维拉帕米可逆转PAF抑制PASMCs膜Ca~(2+)-ATPase活力的效应。  相似文献   

8.
基因工程人干扰素α2b和α2a亚型抗病毒效应的实验研究   总被引:4,自引:0,他引:4  
本文采用鸡胚接种法和微量细胞病变抑制法研究了不同亚型α干扰素(α2aIFN和α2bIFN)抗流感病毒、脊髓灰质炎病毒以及麻疹病毒的作用。结果表明:两种亚型α干扰素均显示明显的抗病毒效应,其中(1)α2bIFN抗流感病毒作用略强于α2aIFN,(2)两亚型α干扰素抗脊髓灰质炎和麻疹病毒作用相似。  相似文献   

9.
ABA诱导蚕豆气孔保卫细胞H2O2的产生   总被引:2,自引:0,他引:2  
以蚕豆叶片下表皮为材料,将荧光探针HPTS导入蚕豆气孔保卫细胞内,利用荧光光谱和激光共聚焦显微技术,检测了ABA诱导蚕豆气孔关闭过程中H2O2的产生。结果表明,ABA和100μmol/L的H2O2可以迅速猝灭HPTS的荧光,CAT几乎可完全阻止9μl0.2mmol/L的ABA引起荧光猝灭。因此,ABA可以诱导气孔保卫细胞产生H2O2,其产生的强度和速度与ABA的浓度直接有关,并且推测:这种H2O2产生可能是ABA诱导气孔关闭过程中信号转导链的一个中间成分。  相似文献   

10.
利用不同浓度Cd2+、Hg2+处理菱幼苗,研究重金属离子对菱生长、超氧化物歧化酶(SOD)、过氧化物酶(POD)活性的影响,比较Cd2+、Hg2+对同一植物的毒性差异。Cd2+、Hg2+各处理浓度均抑制菱幼苗生长,使叶绿素含量下降,但Cd2+的抑制作用比Hg2+的作用明显。Cd2+、Hg2+对SOD、POD活性有不同的影响效果:Cd2+处理最初诱导SOD、POD活性升高,但随浓度加大时间延长酶活性急剧下降;Hg2+处理的酶活性变化相对平缓,其中5μmol/L和10μmol/LHg2+处理的POD活性持续上升。实验结果表明,在相同处理时间和浓度条件下,Cd2+比Hg2+对菱的毒性要大。依据实验结果,作者探讨了重金属对植物的毒害机制  相似文献   

11.
2′,2′-Difluoro-2′-deoxycytidine (dFdC, gemcitabine) is a cytidine analogue active against several solid tumor types, such as ovarian, pancreatic and non-small cell lung cancer. The compound has a complex mechanism of action. Because of the structural similarity of one metabolite of dFdC, dFdUMP, with the natural substrate for thymidylate synthase (TS) dUMP, we investigated whether dFdC and its deamination product 2′,2′-difluoro-2′-deoxyuridine (dFdU) would inhibit TS. This study was performed using two solid tumor cell lines: the human ovarian carcinoma cell line A2780 and its dFdC-resistant variant AG6000. The specific TS inhibitor Raltitrexed (RTX) was included as a positive control. Using the in situ TS activity assay measuring the intracellular conversion of [5-3H]-2′-deoxyuridine or [5-3H]-2′-deoxycytidine to dTMP and tritiated water, it was observed that dFdC and dFdU inhibited TS. In A2780 cells after a 4 h exposure to 1 μM dFdC tritium release was inhibited by 50% but did not increase after 24 h, Inhibition was also observed following dFdU at 100 μM. No effect was observed in the dFdC-resistant cell line AG6000; in this cell line only RTX had an inhibitory effect on TS activity. In the A2780 cell line RTX inhibited TS in a time dependent manner. In addition, DNA specific compounds such as 2′-C-cyano-2′-deoxy-1-beta-D-arabino-pentafuranosylcytosine and aphidicoline were utilized to exclude DNA inhibition mediated down regulation of the thymidine kinase.Inhibition of the enzyme resulted in a relative increase of mis-incorporation of [5-3H]-2′-deoxyuridine into DNA. In an attempt to elucidate the mechanism of in situ TS inhibition the ternary complex formation and possible inhibition in cellular extracts of A2780 cells, before and after exposure to dFdC, were determined. With the applied methods no proof for formation of a stable complex was found. In simultaneously performed experiments with 5FU such a complex formation could be demonstrated. However, using purified TS it was demonstrated that dFdUMP and not dFdCMP competitively inhibited TS with a Ki of 130 μM, without ternary complex formation. In conclusion, in this paper we reveal a new target of dFdC: thymidylate synthase.  相似文献   

12.
4-nitrophenyl 3,4,6-tri-O-acetyl-2-azido-2-deoxy-alpha- and beta-D-mannopyranosides were prepared from methyl 4,6-O-benzylidene-alpha-D-glucopyranoside and 1,3,4,6-tetra-O-acetyl-alpha-D-glucopyranose, respectively. Chemoselective reduction of both azides with hydrogen sulfide readily afforded 4-nitrophenyl 2-acetamido-4,6-di-O-acetyl-2-deoxy-alpha-D- and -beta-D-mannopyranosides in higher yields than reduction with triphenylphosphine or a polymer-supported triarylphosphine. Subsequent de-O-acetylation yielded 4-nitrophenyl 2-acetamido-2-deoxy-alpha-D-mannopyranoside and 4-nitrophenyl 2-acetamido-2-deoxy-beta-D-mannopyranoside in 20% and 44% overall yields, respectively.  相似文献   

13.
以拟南芥为材料,利用药理学实验,结合分光光度法和激光共聚焦显微技术,研究了Ca2+在硫化氢(H2S)诱导拟南芥气孔关闭过程中的作用及其与过氧化氢(H2O2)的关系。结果表明: H2S诱导气孔关闭, Ca2+螯合剂EGTA和质膜Ca2+通道阻断剂硝苯地平(Nif)能不同程度抑制H2S诱导的气孔关闭,而内质网钙泵阻断剂毒胡萝卜素(Thaps)对H2S的作用无显著影响。由此推测, Ca2+参与调节H2S诱导的拟南芥气孔关闭过程,且胞质中Ca2+来源于胞外Ca2+的内流。另外, H2S诱导拟南芥叶片NADPH氧化酶基因AtRBOHD和AtRBOHF以及细胞壁过氧化物酶基因AtPRX34表达增强,促进叶片和保卫细胞中H2O2积累, EGTA对此起抑制作用,而外源CaCl2处理上调AtRBOHD、AtRBOHF和AtPRX34的表达。表明Ca2+可能位于H2O2上游参与H2S诱导的拟南芥气孔关闭过程。  相似文献   

14.
TRAF2 plays a central role in TNF-induced signalling to NF-κB and JNK/p38 MAPK. To better understand the molecular mechanisms that mediate this dual function of TRAF2, we performed a yeast two-hybrid screening for TRAF2 interacting proteins using the Sos recruitment system. This resulted in the identification of the E3 ubiquitin ligase Smurf2 as a TRAF2 binding protein. TRAF2 overexpression was shown to trigger Smurf2 ubiquitination and the formation of a TNF-R2/Smurf2 complex. Smurf2 on its turn promoted TNF-R2 ubiquitination and the relocalization of TNF-R2 as well as TRAF2 to a detergent-insoluble cell fraction. This was associated with enhanced TNF-R2-induced JNK activation, whereas TNF-R2-induced NF-κB activation remained unaffected. These results suggest an important role for Smurf2 binding to TRAF2 in determining specific signalling outputs of TNF-R2.  相似文献   

15.
[2S-2-2H]- and [2R-2-2H]hexadecanoic acids were synthesized in overall yields of 59–67%. Methyl(2R)-2-hydroxyhexadecanoate, from the acid produced by Hansenula sydowiorum, was converted to the p-toluenesulphonate, reduced to trideutero alcohol with lithium aluminium deuteride and oxidized to [2S-2-2H]hexadecanoic acid. Methyl (2S)-2-chlorohexadecanoate, which was a by-product of tosylation and was also prepared by chlorinatioon of the hydroxy ester with thionyl chloride, on reduction and oxidation as before gave [2R-2-2H]-hexadecanoic acid. Intermediates were fully characterized, isotopic purity was 97% and optical purity was maintained throughout the syntheses. Attempts to reduce the tosyl or chloro groups, only, with sodium borodeuteride gave low yields probably due to preferential reduction of the ester group; 1,2-epoxyhexadecane was obtained from the tosylate and 2-chlorohexadecan-1-ol from the chloro ester.  相似文献   

16.
17.
PPP2R2A是PP2A磷酸酶的调控亚基之一,以往的研究报道显示,PPP2R2A可促进肿瘤细胞生存和生长。本研究通过串联亲和纯化联合HPLC-Chip-ESI/MS/MS筛选PPP2R2A的相互作用蛋白质,分析结果显示,L-谷氨酰胺-D-果糖-6-磷酸转氨酶1(Glutamine-fructose-6-phosphate transaminase 1,GFPT1)和L-谷氨酰胺-D-果糖-6-磷酸转氨酶2(Glutamine-fructose-6-phosphate transaminase 2,GFPT2)是PPP2R2A可能的结合蛋白。通过免疫荧光共定位、GST Pull-down和免疫共沉淀等方法,进一步确认了PPP2R2A和GFPT1及GFPT2的相互结合。通过shRNA下调PPP2R2A后,GFPT2的磷酸化水平显著增加,但GFPT1的磷酸化水平改变不明显。GFPT2是O-GlcNAC糖基化修饰通路中的一个限速酶,在乳腺癌细胞MDA-MB-231中下调PPP2R2A后,蛋白质O-GlcNAC糖基化修饰水平增加。这些结果表明,PPP2R2A可直接结合GFPT2,并导致其去磷酸化,进而影响细胞内O-GlcNAC糖基化修饰。  相似文献   

18.
拟南芥血红蛋白1(AtGLB1)与过氧化氢的相互作用   总被引:1,自引:0,他引:1  
拟南芥的血红蛋白1(AtGLB1)属于非共生的血红蛋白。在低氧胁迫中对植物细胞中过氧化氢(H2O2)内稳态的维持起了很重要的作用。为了检测AtGLB1与H2O2能否直接相互作用,我们扩增了拟南芥的AtGLB1基因,并将其克隆到原核表达质粒pET32a中,测序鉴定正确后转化大肠杆菌BL21。IPTG诱导目的蛋白表达后,镍离子亲和层析柱(Ni2+-NTA)纯化了靶蛋白。体外表达的氧合的AtGLB1能与H2O2直接相互作用。因此,与H2O2反应可能是AtGLB1清除低氧胁迫下产生的H2O2的一种方式。  相似文献   

19.
通过化学诱变剂甲基磺酸乙酯(EMS)诱变模式植物拟南芥(Arabidopsis thaliana)获得突变体筛选群体.在5 mmol/L H2O2胁迫下,以叶片温度差异为筛选指标,利用远红外成像技术进行突变体的筛选,获得了对H2O2不敏感突变体hpi1(hydrogen peroxide-insensitive1)和敏感突变体hps1(hydrogen peroxide-sensitive1).进一步研究发现,两种突变均为单基因隐性突变,气孔密度同野生型一样,而叶片温度、气孔开度和叶片失水率则有明显的差异.种子萌发实验表明,hpi1对甘露醇(Man)和NaCl不敏感而对ABA敏感,hps1则对3种胁迫都表现出敏感特性.  相似文献   

20.
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