小麦细胞核仁中rRNA基因转录的超微定位

真核细胞核仁中rRNA基因转录位点是长期以来未能解决的问题。以小麦细胞为研究材料,应用常规电子显微镜技术,观察了小麦细胞核仁纤维中心(Fibrillar centers,FC)内染色质的超微结构;并通过DNA抗体阐明了核仁中DNA位于纤维中心、致密纤维组分(Dense fibrillar component,DFC)以及两者的过渡区域;应用RNA聚合酶I相关转录因子UBF(Upstream binding factor)抗体所做的分析显示,小麦细胞核仁中UBF位于FC与DFC的过渡区域以及DFC中,在FC中没有UBF的存在;进一步借助于RNA/DNA杂合体抗体选择性地直接标记核仁中rRNA基因的转录位点,结果表明了小麦细胞核仁rRNA基因的转录位点是在FC与DFC的过渡区域及DFC中。     

小麦细胞核仁中DNA原位位置与rRNA基因转录位点的研究

以小麦细胞为研究材料, 应用常规电子显微镜技术和DNA细胞化学特异染色NAMA-Ur技术, 在原位水平对核仁中DNA的分布和特征进行了直观的观察。结果表明, 小麦细胞核仁中DNA位于纤维中心(Fibrillar Centers, FC)、致密纤维组分(Dense Fibrillar Component, DFC)以及两者的过渡区域, 并呈现出环绕FC排布的构型; 应用RNP优先染色(Benhard staining)技术分析了核仁中RNP的分布及其原位位置, 直观的显示了小麦细胞核仁中RNP颗粒主要集中在 FC与DFC的过渡区域及DFC和颗粒组分(Granular Component, GC)中; 并且在FC与DFC的过渡区域, 它们不太均匀也不太连续地半围绕着FC而排布; 进一步借助于RNA/DNA杂合体抗体在原位水平标记和分析了细胞核仁中活跃基因转录的精细位点, 结果表明小麦细胞核仁rRNA基因的转录位点位于FC与DFC的过渡区域及DFC中。     

鼠肝细胞核仁结构与rRNA基因转录位点研究

通过常规电子显微镜观察了鼠肝细胞核仁的超微结构,并采用NAMA-Ur细胞化学DNA特异染色方法分析了核仁中DNA的分布及其原位位置,直观的显示了鼠肝细胞核仁DNA来源于核仁伴随染色质,并在核仁DFC区域连续伸展,排布于FC的边缘部位及DFC区域中,进一步借助于RNA/DNA杂合体抗体选择性直接标记核仁中rRNA基因转录位点,结果表明了鼠肝细胞核仁rRNA基因的转录位点是在FC的边缘及DFC区域.     

豌豆细胞核仁中rDNA的超微定位和排布构型

利用细胞化学DNA特异染色法——NAMA-Ur特异染色法对豌豆细胞核仁中rDNA的位置及其排布构型进行了原位观察。结果表明,核仁中的rDNA位于纤维中心(FC)以及FC与致密纤维组分的交界处,以环绕FC的形式排布。不同位置的rDNA成分都具有集缩和解集缩两种形态结构,核仁外的核仁伴随染色质经过核仁通道进入核仁,沿FC周边排列,与其中的DNA相连。     

小麦受精过程中酸性磷酸酶的超微细胞化学定位

小麦（Ｔｒｉｔｉｃｕｍ ａｅｓｔｉｖｕｍ ）受精前成熟胚囊,除胚囊中央细胞的合点端细胞质中有酸性磷酸酶外,其余部位均未发现酸性磷酸酶。受精时期,以下部位存在酸性磷酸酶活性：卵细胞的细胞核内一部分染色质和细胞质中大部分线粒体;精、卵核融合时两核的核周腔内;退化助细胞合点端细胞质和一些液泡内;进入雌性细胞中的两个精核;胚囊各成员细胞的细胞壁及胚囊周围珠心细胞的细胞壁。二细胞原胚中未见有酸性磷酸酶。早期胚乳游离核染色质上有酸性磷酸酶。小麦受精过程酸性磷酸酶的分布特点可能与卵细胞生理状态的变化和细胞质中线粒体的改组、助细胞的退化、精核的生理状态以及精核与卵核的核膜融合等有关。     

小麦珠心细胞衰退过程中ATP酶的超微细胞化学定位

采用磷酸铅沉淀技术对小麦（Ｔｒｉｔｉｃｕｍ ａｅｓｔｉｖｕｍ ）珠心细胞衰退过程进行了ＡＴＰ酶的超微细胞化学定位。初始衰退的珠心细胞,ＡＴＰ酶只定位于细胞膜上,其它部位未见有ＡＴＰ酶活性。衰退中期的珠心细胞,细胞膜上ＡＴＰ酶活性减弱并逐渐消失;细胞核染色质和细胞质中一些细胞器上存在ＡＴＰ酶活性。在严重衰退的珠心细胞中,只在细胞核染色质上存在ＡＴＰ酶活性。珠心细胞的细胞核以两种方式衰退。衰退的细胞核染色质碎片仍存在ＡＴＰ酶活性,并向胚囊方向转移。推测小麦珠心细胞衰退过程中细胞膜上ＡＴＰ酶变化反映了珠心细胞生理状态转变;细胞核染色质上ＡＴＰ酶与其形态变化和运动等有关     

小麦与叶锈菌互作过程中细胞程序性死亡的生化证据（简报）

细胞程序性死亡(Programmed Cell Death,PCD)是一种受基因调控的、主动的、连续的程序化反应。一般发生程序性死亡的细胞具有较为典型的形态及生化特征：细胞收缩、核染色质浓缩、趋边化;DNA在一定位点被核酸内切酶降解成以180bp为基数的片段,在琼脂糖凝胶电泳中呈现“梯”状条带     

转Xa21基因水稻中T-DNA整合的遗传定位

利用转抗白叶枯病基因Xa21的水稻材料,通过TAIL－PCR方法扩增T－DNA整合的侧翼序列。从中筛选属于水稻基因组DNA的T－DNA整合的侧翼序列作为探针,将外源基因整合位点定位到窄叶青／京系17DH群体构建的水稻分子连锁图谱上。共获得属于水稻基因组DNA的T－DNA侧翼序列22个,其中的19个序列在定位群体的两个亲本之间显示RFLP多态性,分别定位在水稻基因组的第3,4,5,7,9,10,11和12染色体上。带有转基因Xa21的T－DNA整合的定位为研究外源基因在不同染色体位点的位置效应和稳定遗传打下基础。     

小麦珠心细胞衰退过程酸性磷酸酶的超微细胞化学定位(英文)

采用磷酸铅盐沉淀技术对小麦（ Ｔｒｉｔｉｃｕｍ ａｅｓｔｉｖｕｍ Ｌ．） 珠心细胞衰退过程进行了酸性磷酸酶的超微细胞化学定位研究。结果显示,在未有明显衰退迹象的一些珠心细胞中,酸性磷酸酶只出现在细胞核轻微凝聚的染色质上。随珠心细胞衰退程度的逐渐增大,其衰退特征越来越明显,酸性磷酸酶依次在细胞质中较小液泡、细胞壁、线粒体、质体以及内质网等结构上出现活性反应。紧连胚囊的珠心细胞衰退程度最大,细胞严重变形,酸性磷酸酶定位于细胞绝大部分结构中,但此时变形的细胞核则无酸性磷酸酶活性反应。研究结果表明,小麦珠心细胞的衰退过程中,酸性磷酸酶存在一个有规律的变化,支持珠心细胞的衰退是属于细胞程序性死亡类型的观点     

The nucleolus and transcription of ribosomal genes

Ribosome biogenesis is a highly dynamic, steady-state nucleolar process that involves synthesis and maturation of rRNA, its transient interactions with non-ribosomal proteins and RNPs and assembly with ribosomal proteins. In the few years of the 21st century, an exciting progress in the molecular understanding of rRNA and ribosome biogenesis has taken place. In this review, we discuss the recent results on the regulation of rRNA synthesis in relation to the functional organization of the nucleolus, and put an emphasis on the situation encountered in mammalian somatic cells.     

Ultrastructural localization of lectin-binding sites in different basement membranes

Summary In the present work we localized binding sites for the lectins WGA, RCA I, con A and SBA at the ultrastructural levels in morphologically different basement membranes. These different basement membranes included (a) thin ones, for example, tubular basement membrane of the mouse kidney which separates epithelial cell layers from mesenchymal cells and glomerular basement membrane which separates epithelial cells from other epithelial cells, (b) thick multilayered ones, for example, Reichert's membrane which is built up during the embryonic development of rodents and as an example of a pathologically thickened basement membrane, the basement membrane of the Engelbreth-Holm-Swarm (EHS) sarcoma. We were able to show that, in contrast to the thick multilayered basement membranes, the thin ones showed a strong positive SBA-binding pattern. Thick basement membranes otherwise revealed very strong labelling with the lectins WGA and RCA I. Our findings lead us to conclude that thin and thick basement membranes differ markedly in the quality and quantity of the carbohydrates which they contain.     

Ultrastructural localization of wheat germ agglutinin-binding sites on surfaces of chick embryo cells during early differentiation.

The objective of this work was to examine changes in a surface component of cells from the chick embryo during morphogenetic migrations of gastrulation. Two electron microscope techniques were used to localize cell-bound wheat germ agglutinin (WGA), a lectin which specifically binds N-acetyl glucosamine residues. One technique involved conjugation of peroxidase to WGA before reaction with the cells; the other technique used glucose oxidase to mark WGA which was already cell-bound. In both cases, binding was revealed using diaminobenzidine. Before formation of the primitive streak, all surfaces of the two-layered embryo bound WGA. After migration of cells through the streak, to form the three-layered embryo, not all cell surfaces bound WGA equally. Epiblast cells generally bound WGA lateral to the primitive streak but not during passage through the streak. Mesenchyme cells, after passage through the streak, bound WGA increasingly as they migrated away from the streak. A WGA-binding matrix was observed in the vicinity of the mesenchyme cells and on the dorsal surface of the endoblast. The ventral surface of the endoblast bound the lectin very poorly. In some instances, a peroxidase reaction product was consistently seen on certain surfaces which was not removable by addition of the simple hapten N-acetyl glucosamine. In these cases, the density of the deposit was lessened by use of diacetyl chitobiose as a hapten. This result, together with the reduction of reaction product following certain hyaluronidase treatments, suggests that WGA may be binding to hyaluronic acid as well as membrane glycoproteins.