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1.
Fe2 -H2O2体系能够有效地降解壳聚糖,反应介质的pH值、反应时间、反应温度、Fe2 浓度及H2O2浓度等实验因素对壳聚糖的降解效果都有程度不同的影响,其中以反应介质的pH值和H2O2浓度对降解反应的影响为最大.在pH值为3~5时Fe2 -H2O2体系降解壳聚糖的活性最高.适当增大H2O2的用量可以增大壳聚糖的降解程度,但当其用量增大至一定程度后,壳聚糖降解产物分子量的下降趋势明显变缓.合理的Fe2 -H2O2体系降解壳聚糖的实验条件为:介质pH值3~5;温度,室温;时间60~90 min;壳聚糖:H2O2:Fe2 =240:12~24:1~2(摩尔比).  相似文献   

2.
证明了用角2πω~2/(1 ω~2)、2π(3 ω~2)和2π/(2 ω~2)在圆周上作插分得到任意n个分点并将圆周分为11个角时,其最小角与最大角之比也至少是ω~2.根据叶序的基本功能,用模糊数学的综合评判理论证明了角2πω~2优于角2πω~2/(1 ω~2)、2π/(3 ω~2)和2π/(2 ω~2),从而从理论上说明了2πω~2作为互生植物的叶序分数所对应的极限角是合理的.  相似文献   

3.
TXA2/PGI2与心血管疾病   总被引:3,自引:0,他引:3  
血栓素(Thromboxane,TXA2)和前列环素(Prostacyclin,PGI2)均为花生四烯酸的代谢物,是前列腺素(Prostaglandins,PGs)中生物活性最强的一对。在正常情况下,二者在体内保持一定的平衡,相互拮抗、相互协调,共同维持血液循环畅通,与心血管疾病关系密切。本文即就其生物特性及与心血管病的关系等进行综述,对人们全面认识TXA2/PGI2具有一定的参考价值。  相似文献   

4.
以拟南芥(Arabidopsis thaliana)为材料,研究了过氧化氢(H2O2)在硫化氢(H2S)调控气孔运动信号转导中的作用。结果表明,光下H2S的供体硫氢化钠(NaHS)能够诱导拟南芥气孔关闭;且能够显著提高叶片和保卫细胞胞质H2O2含量;H2O2的清除剂AsA和H2O2合成酶的抑制剂可不同程度地抑制NaHS诱导的拟南芥气孔关闭及叶片和保卫细胞胞质H2O2水平的升高;NaHS对AtrbohD、AtrbohF、Atpao2和Atpao4突变体气孔关闭、叶片和保卫细胞胞质H2O2水平升高的诱导作用要明显的小于野生型,但对AtPAO2和AtPAO4过表达株系叶片和保卫细胞H2O2水平的升高较野生型显著。据此推测,来源于NADPH氧化酶、细胞壁过氧化物酶和多胺氧化酶途径的H2O2参与H2S诱导的拟南芥气孔关闭。  相似文献   

5.
P2X受体是非选择性阳离子通道,广泛分布于中枢及外周神经系统。近年来,本实验室侧重研究重金属、质子、酒精等对P2X2和P2X4受体的调制。研究发现不同的因素对同一种受体介导的ATP-激活电流有不同的调制作用,如增强效应、抑制效应或者两种效应兼有,而且同一种因素对这两种受体的调制效应也不相同。因此,我们推测P2X受体上存在不同的结合位点,本文主要阐述P2X2和P2X4受体不同的调制位点。  相似文献   

6.
潘庆民1,于振文2,王月福2   总被引:5,自引:0,他引:5  
采用盆栽和水泥池栽研究了追氮时期对小麦光合作用、14C同化物运转分配和硝酸还原酶(NR)活性的影响.结果表明,拔节(雌雄蕊原基形成)期较起身(二棱)期追施氮肥,显著提高了小麦开花后的旗叶叶绿素含量和单叶光合速率;灌浆期旗叶14C同化物向籽粒转移比例显著提高,而在营养器官的滞留比例显著降低;旗叶和根系中硝酸还原酶(NR)活性亦显著提高.小麦穗粒数、粒重和产量增加,蛋白质含量提高.  相似文献   

7.
细胞内线粒体呼吸链过程中的电子漏和神经细胞代谢的酶类如单胺氧化酶(MAO)等可产生活性氧物质(ROS)如H_2O_2等。ROS对细胞有毒性作用,导致细胞死亡,在许多疾病特别是神经退行性疾病中具有重要作用。我们用H_2o_2诱导N-2a神经母细胞瘤细胞,利用光镜、荧光显微镜、透射电镜观察了诱导的N-2a细胞的死亡,结果表明其死亡形式不同于典型的细胞凋亡,而类似于Ⅱ型神经细胞编程性死亡,死亡细胞染色质呈团块状凝集,细胞核膜仍保持完整。DNA不降解形成ladder,且不需要caspase-3,1的活性,但是H_2O_2诱导的Neuro-2a细胞死亡可以被Bcl-X_L,抑制。我们的结果可以说明,ROS介导的细胞毒性作用是导致Ⅱ型神经细胞编程性死亡的一个原因。  相似文献   

8.
胰岛素样生长因子2 mRNA结合蛋白2(insulin growth factor 2 mRNA binding protein 2,IGF2BP2)是一种调节多种生物过程的RNA结合蛋白,最初作为2型糖尿病的相关基因被发现,随着深入的研究,人们发现它在多种肿瘤的发生发展中也起着重要的生物学作用。IGF2BP2可以作为一种m6A阅读器,通过与不同的非编码RNA(如miRNAs、lncRNAs和circRNAs)相互作用参与癌症的发生发展。本次综述总结了IGF2BP2在多种癌症中的生物学作用、机制以及预后潜力,以期为癌症的诊断及预后提供新的标志物,同时为IGF2BP2作为癌症精准化治疗靶点的相关研究提供新的思路。  相似文献   

9.
C_2H_2型锌指蛋白研究进展   总被引:1,自引:0,他引:1  
遗传信息的实现过程离不开基因表达的调控 ,至今为止发现的转录调控因子中有很多含有锌指模体 (zinc fingermotif)结构。锌指蛋白是指含有通过结合Zn2 稳定的短的可以自我折叠形成“手指”结构的一类蛋白质。由于其自身的结构特点 ,可以选择性的结合特异的靶结构 ,使锌指蛋白在基因的表达调控、细胞分化、胚胎发育等生命过程中发挥重要作用。自从 1 983年在爪蟾卵母细胞中发现第一个具有基因转录调控作用的锌指蛋白TFⅢA以来 ,在多种生物中发现的锌指基因已有约 50 0多个 ,其中人基因组中的锌指蛋白基因达 2 0 0多个。…  相似文献   

10.
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   

11.
Mitogen-activated protein kinase (MAPK) cascades play pivotal roles in mediating biotic and abiotic stress responses. Cotton (Gossypium hirsutum) is the most important textile crop in the world, and often encounters abiotic stress during its growth seasons. In this study, a gene encoding a mitogen-activated protein kinase (MAPK) was isolated from cotton, and designated as GhMPK17. The open reading frame (ORF) of GhMPK17 gene is 1494 bp in length and encodes a protein with 497 amino acids. Quantitative RT-PCR analysis indicated that GhMPK17 expression was up-regulated in cotton under NaCl, mannitol and ABA treatments. The transgenic Arabidopsis plants expressing GhMPK17 gene showed higher seed germination, root elongation and cotyledon greening/expansion rates than those of the wild type on MS medium containing NaCl, mannitol and exogenous ABA, suggesting that overexpression of GhMPK17 in Arabidopsis increased plant ABA-insensitivity, and enhanced plant tolerance to salt and osmotic stresses. Furthermore, overexpression of GhMPK17 in Arabidopsis reduced H2O2 level and altered expression of ABA- and abiotic stress-related genes in the transgenic plants. Collectively, these data suggested that GhMPK17 gene may be involved in plant response to high salinity and osmotic stresses and ABA signaling.  相似文献   

12.
13.
Zhang L  Xi D  Li S  Gao Z  Zhao S  Shi J  Wu C  Guo X 《Plant molecular biology》2011,77(1-2):17-31
Mitogen-activated protein kinase (MAPK) cascades play important roles in mediating biotic and abiotic stress responses. In plants, MAPKs are classified into four major groups (A-D) according to their sequence homology and conserved phosphorylation motifs. Compared with well-studied MAPKs in groups A and B, little is known about group C. In this study, we functionally characterised a stress-responsive group C MAPK gene (GhMPK2) from cotton (Gossypium hirsutum). Northern blot analysis indicated that GhMPK2 was induced by abscisic acid (ABA) and abiotic stresses, such as NaCl, PEG, and dehydration. Subcellular localization analysis suggested that GhMPK2 may activate its specific targets in the nucleus. Constitutive overexpression of GhMPK2 in tobacco (Nicotiana tabacum) conferred reduced sensitivity to ABA during both seed germination and vegetative growth. Interestingly, transgenic plants had a decreased rate of water loss and exhibited enhanced drought and salt tolerance. Additionally, transgenic plants showed improved osmotic adjustment capacity, elevated proline accumulation and up-regulated expression of several stress-related genes, including DIN1, Osmotin and NtLEA5. β-glucuronidase (GUS) expression driven by the GhMPK2 promoter was clearly enhanced by treatment with NaCl, PEG, and ABA. These results strongly suggest that GhMPK2 positively regulates salt and drought tolerance in transgenic plants.  相似文献   

14.
该研究在实验室前期研究的基础上,将受脱水、盐胁迫和ABA诱导的柠条锦鸡儿CkLEA4基因转入野生型拟南芥,并利用实时荧光定量PCR从8株纯合体中筛选出3个表达量不同的株系,比较野生型和转CkLEA4基因过表达拟南芥种子在不同胁迫处理下的萌发率,以探讨CkLEA4基因在植物抵抗逆境胁迫中的功能。结果发现:(1)在不同浓度NaCl、甘露醇及ABA处理下,转CkLEA4基因过表达拟南芥种子的萌发率均高于野生型,随着NaCl、甘露醇及ABA浓度增加,各株系萌发率均降低,但野生型的萌发率下降幅度均高于3个过表达株系,并且在200mmol/L NaCl和400mmol/L甘露醇处理下,过表达株系子叶绿化率均显著高于野生型。(2)在低浓度ABA处理下,CkLEA4过表达植株子叶的绿化率也高于野生型。研究表明,柠条锦鸡儿CkLEA4基因提高了拟南芥种子萌发阶段对盐、ABA及渗透胁迫的耐受性。  相似文献   

15.
Gao G  Zhang S  Wang C  Yang X  Wang Y  Su X  Du J  Yang C 《PloS one》2011,6(4):e19406
The phytohormone abscisic acid (ABA) and the lipoxygenases (LOXs) pathway play important roles in seed germination and seedling growth and development. Here, we reported on the functional characterization of Arabidopsis CPR5 in the ABA signaling and LOX pathways. The cpr5 mutant was hypersensitive to ABA in the seed germination, cotyledon greening and root growth, whereas transgenic plants overexpressing CPR5 were insensitive. Genetic analysis demonstrated that CPR5 gene may be located downstream of the ABI1 in the ABA signaling pathway. However, the cpr5 mutant showed an ABA independent drought-resistant phenotype. It was also found that the cpr5 mutant was hypersensitive to NDGA and NDGA treatment aggravated the ABA-induced delay in the seed germination and cotyledon greening. Taken together, these results suggest that the CPR5 plays a regulatory role in the regulation of seed germination and early seedling growth through ABA and LOX pathways independently.  相似文献   

16.
17.
Zhang A  Jiang M  Zhang J  Tan M  Hu X 《Plant physiology》2006,141(2):475-487
The role of mitogen-activated protein kinase (MAPK) in abscisic acid (ABA)-induced antioxidant defense was investigated in leaves of maize (Zea mays) plants. Treatments with ABA or H(2)O(2) induced the activation of a 46-kD MAPK and enhanced the expression of the antioxidant genes CAT1, cAPX, and GR1 and the total activities of the antioxidant enzymes catalase, ascorbate peroxidase, glutathione reductase, and superoxide dismutase. Such enhancements were blocked by pretreatment with several MAPK kinase inhibitors and reactive oxygen species inhibitors or scavengers. Pretreatment with MAPK kinase inhibitors also substantially arrested the ABA-induced H(2)O(2) production after 2 h of ABA treatment, but did not affect the levels of H(2)O(2) within 1 h of ABA treatment. Pretreatment with several inhibitors of protein tyrosine phosphatase, which is believed to be a negative regulator of MAPK, only slightly prevented the ABA-induced H(2)O(2) production, but did not affect the ABA-induced MAPK activation and ABA-enhanced antioxidant defense systems. These results clearly suggest that MAPK but not protein tyrosine phosphatase is involved in the ABA-induced antioxidant defense, and a cross talk between H(2)O(2) production and MAPK activation plays a pivotal role in the ABA signaling. ABA-induced H(2)O(2) production activates MAPK, which in turn induces the expression and the activities of antioxidant enzymes. The activation of MAPK also enhances the H(2)O(2) production, forming a positive feedback loop.  相似文献   

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Catalase and hydrogen peroxide (H(2)O(2)) have been extensively studied for their roles in various stress responses. However, little is known about the triggering mechanisms for stress-induced catalase gene expression or about H(2)O(2) production as a stress signal. It is reported here that ABA-, drought-, and salt stress-induced gene expression of CAT1 catalase is mediated by AtMEK1, an Arabidopsis MAPK kinase, by triggering H(2)O(2) signal production. Both CAT1 expression and AtMEK1 activity were activated by ABA, drought, and salt stresses. The mek1 mutant totally blocked stress-induced CAT1 expression and, interestingly, stress-induced H(2)O(2) production was also blocked. Over-expression of AtMEK1 significantly promoted stress-induced CAT1 expression, and also promoted H(2)O(2) production. These results conclusively indicate that stress-induced CAT1 expression is mediated by AtMEK1 and, furthermore, that the triggering of H(2)O(2) production might be involved in this process, as further proved by the observation that CAT1 expression was induced by applied H(2)O(2.) Surprisingly, the signalling mechanisms for stress-induced gene expression of CAT2 and CAT3 were very different from that of CAT1. Except for drought stress, expression of CAT2 or CAT3 was also activated by salt stress or ABA treatment, and AtMEK1 was not proved to be involved in the drought-induced expression of CAT2 or CAT3. Further studies showed that stomatal movement was much less sensitive to ABA in AtMEK1 mutant (mek1), and over-expression of AtMEK1 in Arabidopsis increased plant resistance to drought or salt stress, which further demonstrated that AtMEK1 is a crucial mediator in plant stress signal transduction.  相似文献   

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