水分胁迫对三种杏树品种的硝酸还原酶的影响

试验研究了不同水分条件下对香白杏、龙王帽杏和金太阳杏杏树体内硝酸还原酶的影响,并就影响进行了讨论。结果表明:水分对硝酸还原酶影响显著,但是极低或者过量水量对其活性有明显抑制作用,除了金太阳杏60%田间持水量外,其他品种40%和60%田间持水量都能增加硝酸还原酶活性。通过水分和活性的相关性分析表明:硝酸还原酶与活性有明显的线性相关性,证明硝酸还原酶可以作为这3种杏树抗旱生化指标。     

Glutathione and its Related Enzymes in the Nile Fish

Glutathione (GSH) and related enzymes, glutathione transferase (GST), glutathione peroxidase (GPx) and glutathione reductase (GR) form an important phase 2 biotransformation enzymes system. The objective of this study was to compare this enzymes system in three fish species from the river Nile, Oreochromis niloticus, Claris lazera and Cyprinus carpio in order to establish the main differences and to purify and characterize GST from the liver of O. niloticus.The level of GSH and the activity of GST, GPx and GR in the liver, kidney and gills of the three fish species were examined. A simple reproducible procedure for the purification of GST from the liver of O. niloticus to homogeneity, which includes chromatography on DEAE- cellulose followed by affinity chromatography on GSH-sepharose was established. The molecular mass was found to be 25,460 Da by SDS-PAGE. The Michaelis-Meneten constants (K_m) of the enzyme for GSH and CDNB were 0.35 mM and 0.42 mM, respectively. The affinity purified enzyme exhibited maximum pH at pH 8.0 and increasing pH above 8.0 did not affect the observed maximum. The purified enzyme acts readily on CDNB, less readily on some standard transferase substrates (1,2-dichloro-4-nitrobenzene and p-nitrophenethyl bromide) and not at all on others (bromosulphophthalein and p-nitrobenzyl chloride). Bromosulfophthalein, cibacron blue and hematin inhibited CDNB-conjugating activity of the purified enzyme with IC₅₀ 0.079, 3.98 and 0.126 μM, respectively.     

Effect of molybdenum stress on growth,yield and seed quality in black gram

Black gram (Vigna mungo L.) var. Shyam plants were raised in refined sand at four levels of molybdenum (Mo), i.e., low (0.002 µM) to excess (2 µM) for 70 days. The molybdenum deficiency symptoms appeared as interveinal chlorosis of young and middle leaves. Compared to control (0.2 µM Mo), total dry matter, seed yield and seed protein decreased at low and excess Mo. The concentration of Mo in leaves and seed as well as activity of nitrate reductase increased with an increase in Mo supply. Low and excess Mo deteriorated the quality of seeds by lowering the content of starch, sugars, protein, and nitrogen and increasing electrical conductivity of seed leachate. Molybdenum deficiency and excess both resulted in production of lightweight immature seeds, poor in vigor and germination potential. The values of sufficiency and threshold of toxicity in leaves were 0.078 and 2.15 µg Mo g^?1 dry matter of black gram.     

花生硝酸还原酶与根瘤中固氮酶活性的研究

花生品种间根瘤量的变化有显著差异,但每克根瘤中固氮酶活性则差异不显著。固氮酶活性在全生育期出现两次高峰,分别在下针期和结荚期,而单株根瘤中固氮酶活性和单株根瘤量均在结荚期出现一次高峰。花生主茎复叶硝酸还原酶活性(NRA)在生育前期出现一次高峰,其活性的高低与品种耐肥性呈负相关。NRA 和根瘤中固氮酶活性有正相关     

高粱叶片硝酸还原酶活性及含氮量与产量相关性分析

叶片硝酸还原酶活性和氮含量是影响高梁产量的重要生理指标。以目前辽宁省主推高梁品种为材料,研究了生育中后期叶片硝酸还原酶活性和氮含量与高粱产量和产量构成因素之间的关系。结果表明：辽杂10、辽杂18、锦杂100的产量较高,达到8100．00kg·hm^-1以上。显著或极显著高于其他品种。开花期6个品种的叶片硝酸还原酶活性和氮含量高于灌浆期,且高产品种两个时期的叶片硝酸还原酶活性和氮含量高于低产品种。生育中后期叶片硝酸还原酶活性和氮含量高．有利高粱穗粒数的增加和籽粒产量的形成。     

猕猴桃GalUR表达与抗坏血酸积累的关系

 通过RT-PCR从美味猕猴桃（Actinidia deliciosa）果实中克隆了D–半乳糖醛酸还原酶（GalUR）全长 cDNA序列,并分析其序列特征,进行原核表达,制备特异抗体,分析其mRNA及蛋白表达水平与果实发育过程及不同组织中抗坏血酸（AsA）合成和积累的关系。结果表明：克隆的GalUR cDNA（GenBank登录号为GU339035）包含的最大开放阅读框（open reading frame,ORF）为990 bp,编码329个氨基酸残基,预测分子量为37 kD,与报道的草莓等其他植物GalUR具有较高的相似性。构建的pET-32a（＋）-GalUR载体在大肠杆菌BL21（E. coli BL21）中异源表达后,获得了主要以包涵体存在约58 kD的融合蛋白GalUR-His（His约21 kD）。以该蛋白制备抗体,与重组蛋白的Western杂交表明该抗体能与GalUR蛋白发生特异反应。对猕猴桃可溶性蛋白杂交显示,猕猴桃体内GalUR蛋白的分子量约37 kD。在猕猴桃不同组织和发育过程中,GalUR表达水平与AsA含量表现为高度一致,但前体饲喂发现,与L–半乳糖相比,D–半乳糖醛酸并不能有效促进猕猴桃AsA的合成。这些结果表明以单体形式存在的GalUR与猕猴桃AsA合成有着密切关系,但它可能并不是猕猴桃AsA积累的主要调控环节。     

巨尾桉EuGR1基因的克隆及其低温胁迫下的表达特性分析

本研究通过反转录PCR方法克隆了巨尾桉谷胱甘肽还原酶（Glutathione reductase,简称GR）基因,该基因定位于巨尾桉细胞质、长度为1485 bp,在NCBI申请基因注册（GenBank Accession Number KU904639）。构建了pET-EuGR1原核表达载体,酶活检测表明转化菌株GR活性较高。利用实时定量 PCR分析巨尾桉EuGR1的时空表达特性,结果表明：EuGR1的表达量随着巨尾桉叶片的成熟而降低,在幼叶中表达量最大,近根部的叶片表达量最低;在巨尾桉组培苗中,EuGR1在茎中表达量最大,叶中表达量较低,根中表达量最低。通过转基因抗寒巨尾桉温室苗研究EuGR1基因在低温胁迫下的表达模式,发现常温和低温胁迫下耐寒性强的株系其EuGR1的表达量较高（如P40、P41、P52）,耐寒性弱的株系其EuGR1的表达量较低（如P36、F44、F76）,说明巨尾桉EuGR1的表达量与植株的抗寒能力具有相关性。随着低温胁迫时间的延长,EuGR1的表达量在36 h后出现降低趋势,表明EuGR1在桉树耐低温胁迫的前期发挥作用较大。     

几种树种水浸液对杉木叶片硝酸还原酶的效应

采用完全随机区组设计,用马尾松(Pinusmassoniana)、木荷(Schimasuperba)、赤楠(Syzygiubuxifolium)、杉木(Cunninghamialanceolata)的枝叶1∶6浓度水浸液和清水共5个不同处理浇灌盆栽的杉木幼苗,2a后对其叶片的硝酸还原酶活性进行测定。结果表明,经过几种杉木伴生种水浸液处理2a后杉木的硝酸还原酶活性比杉木水浸液及清水处理的有较大程度的提高,其中经过马尾松水浸液处理的杉木叶片的硝酸还原酶活性最高,而经杉木枝叶水浸液处理的硝酸还原酶活性最低。