植物的硅素营养研究综述

本文阐述了硅在植物中的形态、分布、吸收、积累、生理作用及其与其它元素的关系。研究表明：1．硅主要以二氧化硅胶(SiO2.nH2O)的无机物形态存在于植物表皮细胞和细胞壁。植物体内硅的含量在不同物种间差异很大。根据硅的含量,可将一般栽培植物分为三种类群;同时根据植物硅钙摩尔比值可将植物分为喜硅植物和非喜硅植物。硅在植物各部分分布不均匀,并且随着植株的生长发育,植株中的硅含量不断变化。植物中硅的积累受环境中多种因素的影响。2．植物主要以单硅酸形态吸收硅,不同植物吸收硅的能力不同。水稻具有主动吸硅能力,其吸收过程受体内代谢活动影响<请合法使用软件>其它大多数植物主要以被动方式吸收硅,但不排除具有选择性吸收硅的可能性。3．硅对植物的生长发育产生影响。硅是一些植物(如禾本科植物、甜菜、木贼属植物及某些硅藻)的必需元素。硅对其它很多植物具有有益作用。硅对植物的作用主要表现在对形态结构、生理过程和抗逆能力三方面的影响 上。在去硅条件下,多种植物表现出缺硅症状。4．硅对植物吸收利用对其它营养元素产生影响。硅对不同元素的影响方式和程度不同,同时随着植物的生长发育,对某种元素的作用常发生变化。     

植物的硅素营养研究综述

本文阐述了硅在植物中的形态、分布、吸收、积累、生理作用及其与其它元素的关系。研究表明：１硅主要以二氧化硅胶（ＳｉＯ２．ｎＨ２Ｏ）的无机物形态存在于植物表皮细胞和细胞壁。植物体内硅的含量在不同物种间差异很大。根据硅的含量,可将一般栽培植物分为三种类群;同时根据植物硅钙摩尔比值可将植物分为喜硅植物和非喜硅植物。硅在植物各部分分布不均匀,并且随着植株的生长发育,植株中的硅含量不断变化。植物中硅的积累受环境中多种因素的影响。２植物主要以单硅酸形态吸收硅,不同植物吸收硅的能力不同。水稻具有主动吸硅能力,其吸收过程受体内代谢活动影响＜请合法使用软件＞其它大多数植物主要以被动方式吸收硅,但不排除具有选择性吸收硅的可能性。３硅对植物的生长发育产生影响。硅是一些植物（如禾本科植物、甜菜、木贼属植物及某些硅藻）的必需元素。硅对其它很多植物具有有益作用。硅对植物的作用主要表现在对形态结构、生理过程和抗逆能力三方面的影响上。在去硅条件下,多种植物表现出缺硅症状。４硅对植物吸收利用对其它营养元素产生影响。硅对不同元素的影响方式和程度不同,同时随着植物的生长发育,对某种元素的作用常发生变化。     

硅在水稻生活中的作用

水稻为喜硅植物,硅是水稻生命活动中大量需要和吸收的重要元素,阐述了水稻体内硅的含量,存在形式,分布,水稻对硅的吸收,运转,硅的生理作用;硅肥及其施用与增产效果。     

植物抗体

抗体结合抗原的高度亲和性和特异性,以及抗体近乎无限的多态性,使得抗体成为蛋白质中的一个异常有用的类别。单链抗原结合蛋白及催化抗体的设计研究进展,为抗体应用性及新的性能的提高提供了保证。因此,Hiatt,Cafferky和Bowdish报道的在植物体内抗体     

繁茂膜海绵硅聚合酶抗体制备及其在造骨细胞鉴别中的应用

为准确鉴别海绵造骨细胞,分别提取了繁茂膜海绵、多皱软海绵和澳大利亚厚皮海绵的硅聚合酶,以繁茂膜海绵硅聚合酶为抗原制备抗体,效价为1∶9600。SDSPAGE显示三种海绵硅聚合酶的亚基分布在28kD左右;建立竞争抑制性检测方法并结合WesternBlotting检测,显示该抗体可与繁茂膜海绵硅聚合酶特异性结合,且与另外两种海绵硅聚合酶几乎无交叉反应。利用该抗体对繁茂膜海绵组织和体外培养细胞进行免疫组织化学染色,均可显示造骨细胞的分布。结果提示硅聚合酶抗体可以特异性与繁茂膜海绵造骨细胞内的硅聚合酶结合,因此,该抗体可以用于造骨细胞的鉴别。     

狂犬病病毒CVS-11核蛋白B细胞线性抗原表位研究

为阐明狂犬病病毒CVS-11核蛋白B细胞线性抗原表位,本研究通过合成肽模拟B细胞线性抗原表位,采用免疫学方法对生物信息学分析获得的狂犬病病毒CVS-11核蛋白潜在B细胞线性抗原表位进行验证。结果显示,狂犬病病毒CVS-11核蛋白355~369、385~400位氨基酸序列合成肽免疫小鼠血清经间接酶联免疫吸附试验(Enzyme-linked immunosorbent assay,ELISA)检测抗多肽抗体效价达到1∶12 800以上;抗多肽抗体在免疫印迹试验(Western blot,WB)中识别变性狂犬病病毒CVS-11核蛋白抗原,在间接荧光抗体试验(Indirect fluorescent antibody,IFA)中识别感染BHK-21细胞的狂犬病病毒CVS-11核蛋白抗原。因此,狂犬病病毒CVS-11核蛋白355~369、385~400位氨基酸序列经证实为B细胞线性抗原表位。     

人钙周期蛋白结合蛋白（hCacyBP）基因的克隆与表达

筛选cDNA文库得到了人的钙周期蛋白结合蛋白基因 ,将此基因的全编码区克隆到原核表达载体pET2 8上 ,诱导目的蛋白质表达以后将重组蛋白质用亲和层析的方法进行纯化 ,得到了纯度很好的重组的目的蛋白质 ,以此作为抗原免疫动物 ,得到抗钙周期蛋白结合蛋白的特异多克隆抗体。Western印迹的结果表明 ,该基因在小鼠多种组织中广泛表达 ;免疫组化的结果表明 ,BT32 5细胞诱导分化后钙周期蛋白结合蛋白分布有变化 ,由分布于胞质中转向分布于胞核和核周胞质     

水稻U-Box蛋白质在不同发育时期的表达分析

真核生物基因组中广泛存在U-Box基因,其编码蛋白大部分是泛素系统中决定底物特异性识别的E3蛋白,其构象与RING-finger极其相似．U-Box蛋白质能促进底物蛋白泛素化降解,对细胞内异常蛋白的降解及质量控制方面发挥着重要的作用．水稻基因组中有77个U-Box蛋白质,系统了解它们的表达可为功能研究提供数据．制备针对水稻U-Box蛋白质的抗体,了解水稻中U-Box蛋白质在不同发育时期的表达信息,为功能研究积累数据．选取了4个水稻U-Box蛋白质,其共同结构特点为U-Box结构在N端,C端有ARM结构．用计算机软件预测抗原决定簇,细菌体系体外表达、纯化U-Box蛋白质的片段,免疫动物制备多克隆抗体,用Western blotting检测U-Box蛋白质在水稻品种93-11苗期地上部和地下部、分蘖期根和茎、孕穗期剑叶和幼穗、开花期剑叶和穗子、成熟期剑叶和种子中的表达,并与EST数据库中公布的U-Box蛋白质EST数据进行了比较分析．体外克隆表达后,获得了纯化的蛋白质,制备的抗体特异性强,蛋白质印迹(Western blotting)检测可见一条明显的主带,其中Os06g01304和Os12g38210两个蛋白质的表观分子质量与预测分子质量相符,Os01g66130和Os08g01900两个蛋白质的表观分子质量低于预测分子质量．4个U-Box蛋白质在水稻生长发育的不同时期或部位基本上是组成型表达,且表达量接近．对NCBI上公布的来自274个文库100万条以上的EST进行分析,可以看出4个U-Box蛋白质EST的数量分布大致均匀,与Western blotting结果揭示的组成型表达平行,与ATPase、HSP81-3、EGF-1 alpha和RuBisCo等对照基因相比,U-Box基因的EST数目相对很少,说明它们属于低丰度转录的基因．选取了4个水稻U-Box蛋白质,通过抗原决定簇预测,表达片段蛋白,制备了特异性抗体,证明了这一技术路线的可行性．利用抗体对水稻不同发育时期材料进行蛋白质表达谱研究,发现这些U-Box蛋白质呈组成型表达,与EST数据揭示的结果具有平行性．所制备的抗体也为相关功能研究,如免疫共沉淀、ChIP-on-chip、Pull-down以及在抗病、抗逆反应中U-Box蛋白质的表达等,积累了 资源．     

免疫球蛋白的基因和基因工程

免疫球蛋白具有抗体活性、能与相应的抗原专一地结合,为生物体内普遍存在的最主要的一类抗体蛋白质。免疫球旦白不仅存在于血液中与其它体液中,同时也分布在淋巴细胞膜表面上,所以称前者为分泌型抗体,而称后者为膜结合型抗体。     

SARS 冠状病毒 S 蛋白受体结合结构域的表达及其表位作图

严重急性呼吸综合征 (SARS) 是一种新出现的人类传染病,该病的病原是 SARS 冠状病毒 (SARS-CoV). S 蛋白是 SARS 冠状病毒的一种主要结构蛋白,它在病毒与宿主细胞受体结合以及诱导机体产生中和抗体中起重要作用 . 研究表明 S 蛋白与受体结合的核心区域为第 318 ~ 510 氨基酸残基的片段 . 首先克隆并用 pGEX-6p-1 载体融合表达了该受体结合结构域,并且通过蛋白质印迹分析表明,该受体结合结构域融合蛋白能被 SARS 康复患者血清和 S 蛋白特异的单克隆抗体所识别 . 为了对这一区域进行抗原表位作图,进一步设计了一套 23 个覆盖受体结合结构域的长 16 个氨基酸残基的部分重叠短肽,并进行了 GST 融合表达 . 用免疫动物血清和单克隆抗体 D3D1 对 23 个融合蛋白进行蛋白质印迹和 ELISA 免疫反应性分析,结果鉴定出两个抗原表位 SRBD3(F334PSVYAWERKKISNCV349) 和表位 D3D1 (K447LRPFERDI455). 其结果对进一步分析 S 蛋白结构与功能以及诊断试剂和基因工程疫苗的研究有一定意义 .     

Nicotianamine synthase gene expression differs in barley and rice under Fe-deficient conditions

Nicotianamine (NA) is an intermediate in the biosynthetic pathway of the mugineic acid family phytosiderophores (MAs), which are crucial components of the iron acquisition apparatus of graminaceous plants. In non-graminaceous plants, NA is thought to be an essential chelator for metal cation homeostasis. Thus NA plays a key role in Fe metabolism and homeostasis in all higher plants. Nicotianamine synthase (NAS, EC 2.5.1.43) catalyzes the trimerization of S-adenosylmethionine to form one molecule of NA. Barley, a plant that is resistant to Fe deficiency, secretes large amounts of MAs, whereas rice, a plant that is susceptible to Fe deficiency, secretes only small amounts. In this study we isolated a genomic fragment containing HvNAS1 from barley and three rice cDNA clones, osnas1, osnas2 and osnas3, from Fe-deficient rice roots. We also isolated a genomic fragment containing both OsNAS1 and OsNAS2. In contrast to barley, in which Fe deficiency induces the expression of NAS genes only in roots, Fe deficiency in rice induced NAS gene expression in both roots and chlorotic leaves. The amounts of endogenous NA in both the roots and leaves were higher than in barley. We introduced barley genomic DNA fragments containing HvNAS1 with either 9 or 2 kb of the 5'-flanking region into rice, using Agrobacterium-mediated transformation. Fe deficiency induced HvNAS1 expression in both roots and leaves of the transgenic rice, as occurs with rice NAS genes. Barley and rice NAS genes are compared in a discussion of alteration of the NAS genes during adaptation to Fe deficiency.     

水稻谷氨酰胺合成酶同工酶免疫学性质比较研究

用纯化的水后（Ｏｒｙｚａ ｓａｔｉｖａ Ｌ．）根部存在的两种谷氨酰胺合成酶（ＧＳ）同工酶ＧＳｒａ和ＣＳｒｂ分别免疫兔子,得到相应的抗体。免疫扩散和免疫印迹实验表明,ＣＳｒａ、ＧＳｒｂ的抗体对ＧＳ及其同工酶是的。免疫沉淀试验表明,ＧＳｒａ、ＧＳｒｂ不仅识别它的相应的抗原,而且也能很好地识别彼此的抗原。这两种抗体也能较好地识别水稻叶片胞液型的ＧＳＴ,但对水稻叶片和菠菜（Ｓｐｉｎａｃｉａ ｏｌｅｒａｃｅ     

Induced activity of adenine phosphoribosyltransferase (APRT) in iron-deficiency barley roots: a possible role for phytosiderophore production

To isolate the genes involved in the response of graminaceous plants to Fe-deficient stress, a protein induced by Fe-deficiency treatment was isolated from barley (Hordeum vulgare L.) roots. Based on the partial amino acid sequence of this protein, a cDNA (HvAPT1) encoding adenine phosphoribosyltransferase (APRT: EC 2.4.2.7) was cloned from a cDNA library prepared from Fe-deficient barley roots. Southern analysis suggested that there were at least two genes encoding APRT in barley. Fe deficiency increased HvAPT1 expression in barley roots and resupplying Fe to the Fe-deficient plants rapidly negated the increase in HvAPT1 mRNA. Analysis of localization of HvAPT1-sGFP fusion proteins in tobacco BY-2 cells indicated that the protein from HvAPT1 was localized in the cytoplasm of cells. Consistent with the results of Northern analysis, the enzymatic activity of APRT in barley roots was remarkably increased by Fe deficiency. This induction of APRT activity by Fe deficiency was also observed in roots of other graminaceous plants such as rye, maize, and rice. In contrast, the induction was not observed to occur in the roots of a non-graminaceous plant, tobacco. Graminaceous plants generally synthesize the mugineic acid family phytosiderophores (MAs) in roots under Fe-deficient conditions. In this paper, a possible role of HvAPT1 in the biosynthesis of MAs related to adenine salvage in the methionine cycle is discussed.     

Enhanced tolerance of rice to low iron availability in alkaline soils using barley nicotianamine aminotransferase genes

One of the widest ranging abiotic stresses in world agriculture arises from low iron (Fe) availability due to high soil pH, with 30% of arable land too alkaline for optimal crop production. Rice is especially susceptible to low iron supply, whereas other graminaceous crops such as barley are not. A barley genomic DNA fragment containing two naat genes, which encode crucial enzymes involved in the biosynthesis of phytosiderophores, was introduced into rice using Agrobacterium-mediated transformation and pBIGRZ1. Phytosiderophores are natural iron chelators that graminaceous plants secrete from their roots to solubilize iron in the soil. The two transgenes were expressed in response to low iron nutritional status in both the shoots and roots of rice transformants. Transgenic rice expressing the two genes showed a higher nicotianamine aminotransferase activity and secreted larger amounts of phytosiderophores than nontransformants under iron-deficient conditions. Consequently, the transgenic rice showed an enhanced tolerance to low iron availability and had 4.1 times greater grain yields than that of the nontransformant rice in an alkaline soil.     

Immunological characterization of a 36 kDa Fe deficiency specific peptide in barley roots

In a previous paper we reported that an acidic 36 kDa peptide is the most strongly induced peptide among several peptides induced by Fe deficiency in barley roots. In this paper, polyclonal antibodies were raised against the 36 kDa peptide. This peptide appeared in the roots of all the graminaceous species tested (barley, rye, wheat, oat, maize, sorghum and rice) in response to Fe deficiency. More of the peptide was found in the roots of graminaceous species which secrete higher amounts of mugineic acids (MAs) under Fe deficient nutrition status. Induction of the 36 kDa peptide was first observed on the third day of Fe deficiency, rising to a maximum value on the seventh day. The trend has a positive correlation with secretion of MAs during Fe deficiency. Further, resupply of Fe resulted in a decrease in peptide production on the second day, reaching a control level on the seventh day. The rate of decrease in peptide production was observed to be slower than that of MA secretion. Other nutrient stresses such as B excess, B deficiency, Cu excess, Cu deficiency, Mn excess, Mn deficiency, Zn excess and Zn deficiency induced far less of the peptide. The specific expression of the 36 kDa peptide in roots of graminaceous species under Fe deficiency suggested the positive association of the peptide with a specific Fe deficiency tolerance mechanism in graminaceous plants.     

Cloning two genes for nicotianamine aminotransferase, a critical enzyme in iron acquisition (Strategy II) in graminaceous plants

Nicotianamine aminotransferase (NAAT), the key enzyme involved in the biosynthesis of mugineic acid family phytosiderophores (MAs), catalyzes the amino transfer of nicotianamine (NA). MAs are found only in graminaceous plants, although NA has been detected in every plant so far investigated. Therefore, this amino transfer reaction is the first step in the unique biosynthesis of MAs that has evolved in graminaceous plants. NAAT activity is dramatically induced by Fe deficiency and suppressed by Fe resupply. Based on the protein sequence of NAAT purified from Fe-deficient barley (Hordeum vulgare) roots, two distinct cDNA clones encoding NAAT, naat-A and naat-B, were identified. Their deduced amino acid sequences were homologous to several aminotransferases, and shared consensus sequences for the pyridoxal phosphate-binding site lysine residue and its surrounding residues. The expression of both naat-A and naat-B is increased in Fe-deficient barley roots, while naat-B has a low level of constitutive expression in Fe-sufficient barley roots. No detectable mRNA from either naat-A or naat-B was present in the leaves of either Fe-deficient or Fe-sufficient barley. One genomic clone with a tandem array of naat-B and naat-A in this order was identified. naat-B and naat-A each have six introns at the same locations. The isolation of NAAT genes will pave the way to understanding the mechanism of the response to Fe in graminaceous plants, and may lead to the development of cultivars tolerant to Fe deficiency that can grow in calcareous soils.