何首乌种特异DNA探针的筛选

为筛选得到何首乌(Fallopia multiflora)种特异DNA探针,通过何首乌gDNA和其近缘植物毛脉蓼(F.multifora var.cillinerve)gDNA之间的的抑制消减杂交(Suppression subtraction hybridization,SSH)得到何首乌的差减片段,再将标记的差减片段和多物种gDNA阵列杂交筛选得到了4条何首乌DNA探针,探针通过反向斑点杂交检测,能很好地区分何首乌及其混伪品.获得的探针在中药鉴定基因芯片的制备及何首乌种质和生药鉴定方面具应用前景.     

Phylogenetic meaning of the kingdom concept: an unusual ribosomal RNA from Giardia lamblia

An analysis of the small subunit ribosomal RNA (16S-like rRNA) from the protozoan Giardia lamblia provided a new perspective on the evolution of nucleated cells. Evolutionary distances estimated from sequence comparisons between the 16S-like rRNAs of Giardia lamblia and other eukaryotes exceed similar estimates of evolutionary diversity between archaebacteria and eubacteria and challenge the phylogenetic significance of multiple eukaryotic kingdoms. The Giardia lamblia 16S-like rRNA has retained many of the features that may have been present in the common ancestor of eukaryotes and prokaryotes.     

Nanoscale science of single molecules using local probes

Experiments on individual molecules using scanning probe microscopies have demonstrated an exciting diversity of physical, chemical, mechanical, and electronic phenomena. They have permitted deeper insight into the quantum electronics of molecular systems and have provided unique information on their conformational and mechanical properties. Concomitant developments in experimentation and theory have allowed a diverse range of molecules to be studied, varying in complexity from simple diatomics to biomolecular systems. At the level of an individual molecule, the interplays of mechanical and electronical behavior and chemical properties manifest themselves in an unusually clear manner. In revealing the crucial role of thermal, stochastic, and quantum-tunneling processes, they suggest that dynamics is inescapable and may play a decisive role in the evolution of nanotechnology.     

植物病毒标记胶体金探针的制备

对用于植物病毒标记的几类胶体金探针的制备及其标记技术进行了研究。比较了不同情况下胶体金探针的选择、制备与保存的关键技术环节,比较了提高标记强度与特异性的方法,并且对五种植物病毒进行了标记。     

Requirements for growth of single human cells

A minimal growth medium supplemented with dialyzed serum, which sufficed for the propagation of a wide variety of human cell strains in heavily inoculated monolayer and suspension cultures, did not permit the regular or optimal growth of small numbers of HeLa, HeLa S3, conjunctiva, or KB cells deriving from suspension cultures. At threshold concentrations of serum, the plating efficiency of single cells was greatly reduced as compared with their plating efficiency in a medium containing dialyzed serum instead of whole serum, and the clones which did develop grew at a slower rate. The nutritional deficiency could be overcome by adding the seven amino acids which are ordinarily not nutritionally essential. In most of the experiments serine alone sufficed.     

A single adenosine with a neutral pKa in the ribosomal peptidyl transferase center

Biochemical and crystallographic evidence suggests that 23S ribosomal RNA (rRNA) is the catalyst of peptide bond formation. To explore the mechanism of this reaction, we screened for nucleotides in Escherichia coli 23S rRNA that may have a perturbed pKa (where Ka is the acid constant) based on the pH dependence of dimethylsulfate modification. A single universally conserved A (number 2451) within the central loop of domain V has a near neutral pKa of 7.6 +/- 0.2, which is about the same as that reported for the peptidyl transferase reaction. In vivo mutational analysis of this nucleotide indicates that it has an essential role in ribosomal function. These results are consistent with a mechanism wherein the nucleotide base of A2451 serves as a general acid base during peptide bond formation.     

尖刀镰刀孢病原菌ITS和5.8SrDNA的PCR鉴定

通过对ITS/5.8SrDNA区域的PCR和巢式PCR扩增检测真菌DNA,同时评估了PCR和巢式PCR技术的敏感性和特异性。证实了通过PCR和巢式PCR扩增不同种真菌菌株ITS/5.8SrDNA的可行性,通过PCR产物的测序及GenBank比对,能成功检测出该真菌菌株。说明通过对真菌ITS/5.8SrDNA区域的扩增是一种快速检测真菌的方法。     

Steroid-sensitive single neurons in rat hypothalamus and midbrain: identification by microelectrophoresis

Minute amounts of Na-dexamethasone-21-phosphate administered by microelectrophoresis to the immediate extracellular environment promptly suppressed electrical activity of 15 out of 115 hypothalamic and mesencephalic neurons, the effect being readily reversible. Such neurons marked with fast green were found to lie in circumscribed areas of the periventricular gray of the third ventricle and aqueduct, and may represent a site of action of adrenocortical steroids in the regulation of corticotrophin releasing factor and/or adrenocortico-tropin secretion by negative feedback.     

Microcolumn separations and the analysis of single cells

Capillary zone electrophoresis and open tubular liquid chromatography are two examples of an emerging area of analytical instrumentation known as microcolumn separations. The high resolution and small sample requirements of these methods make them suitable for the quantitative, multicomponent chemical analysis of single cells. Appropriate instrumentation for the analysis of nanoliter and subnanoliter samples is discussed. Data from the analysis of individual neurons are presented, including amino acid and neurotransmitter content.     

Zonal ultracentrifuge for the separation of ribosomal subunits

Ribosomal subunits were prepared by means of the Anderson zonal ultracentrifuge. With this technique it is possible to separate more than 300 milligrams of subunits with complete resolution in a single run, as compared with about 2 milligrams with conventional rotors. Superior resolution is achieved in the zonal ultracentrifuge, affording possibilities for the detection and preparation of minor ribosomal components.     

Neuronal activity in narcolepsy: identification of cataplexy-related cells in the medial medulla

Narcolepsy is a neurological disorder characterized by sleepiness and episodes of cataplexy. Cataplexy is an abrupt loss of muscle tone, most often triggered by sudden, strong emotions. A subset of cells in the medial medulla of the narcoleptic dog discharged at high rates only in cataplexy and rapid eye movement (REM) sleep. These cells were noncholinergic and were localized to ventromedial and caudal portions of the nucleus magnocellularis. The localization and discharge pattern of these cells indicate that cataplexy results from a triggering in waking of the neurons responsible for the suppression of muscle tone in REM sleep. However, most medullary cells were inactive during cataplexy but were active during REM sleep. These data demonstrate that cataplexy is a distinct behavioral state, differing from other sleep and waking states in its pattern of brainstem neuronal activity.     

基于rDNA-ITS序列的天门冬拟茎点霉与相似种的系统发育关系

芦笋茎枯病由天门冬拟茎点霉(Phomopsis asparagi)引起,为明确P.asparagi与寄生在其他蔬菜、水果和经济林木等植物上的拟茎点霉不同种之间的系统发育关系,对分离至福建漳州的P.asparagi菌株及从Gen Bank下载的相关菌株的35条ITS序列进行多序列比对分析,并用Neighbor-Joining法构建系统发育树。系统发育分析结果显示:35个菌株被划分为Ⅰ、Ⅱ和Ⅲ组群;P.asparagi与葡萄拟茎点霉(P.viticola)、叶下朱生拟茎点霉(P.phyllanthicola)、杨桃拟茎点霉(P.averrhoae)、大豆茎溃疡病菌(Diaporthe phaseolorum)聚在I组群的A亚群,它们的系统学关系最近;大豆拟茎点霉(P.longicolla)、大豆间座壳菌(Diaporthe sojae)、褐纹拟茎点霉(P.vexans)、光叶子花拟茎点霉(P.glabrae)、柑橘间座壳菌(Diaporthe citri)、黄瓜间座壳菌(Diaporthe sclerotioides)聚在Ⅱ组群,它们与P.asparagi的系统学关系较远;昏暗拟茎点霉(P.obscurans)单独聚在最远的分支上(Ⅲ组群),其与P.asparagi的系统学关系最远。     

Algae: amounts of DNA and organic carbon in single cells

An analysis of ten different unicellular algae, varying in size and containing from 10 to 6000 picograms of carbon per cell, indicates that the amount of DNA per cell is in direct proportion to cell size. The content of DNA is equal to approximately 1 to 3 percent af the cellular organic carbon.     

Turgor pressure: direct manometric measurement in single cells of Nitella

A small capillary, fused at one end, serves as a micromanometer when the open end is inserted into a large Nitella cell. The cell's ability to compress the gas reveals its turgor pressure directly-save for a small correction due to capillarity. The method gives a lower limit to turgor pressure for the same cell in the normal state. The common method, incipient plasmolysis, gives an upper limit. On Nitella axillaris cells the two methods limit the turgor pressure at 5.1 to 5.7 atmospheres. The manometric method is also applicable to growing cells, where osmotic equilibrium is not present.     

Autoradiographic plaques for the detection of antibody formation to soluble proteins by single cells

Single cells that synthesize antibody to soluble proteins can be detected and counted by an autoradiographic procedure. The method is based on the specific binding of I(131)-labeled antigen to the antidogy which has been produced by and has diffused around cells in an agarose medium and which has been precipitated by an antibody to gamma globulin. The antigen-binding zones appear as dark spots on high-speed x-ray film exposed to the dried agarose preparations.     

Isopycnic centrifugation for the isolation of DNA strands coding for ribosomal RNA

Denatured DNA preparations from Escherichia coli were centrifuged to equilibrium in cesium chloride solutions. Hybridizing experiments with radioactively labeled ribosomal RNA showed that the DNA strands complementary to ribosomal RNA were distributed on the heavy side of the DNA band. By fractionating this band the DNA strands coding for ribosomal RNA may be enriched 5- to 20- fold.     

鸡胚肺动脉内皮细胞与平滑肌细胞的分离培养及鉴定

探索简单快速实用的鸡胚肺动脉内皮细胞和平滑肌细胞培养方法:在严格无菌条件下对肺动脉内皮细胞和平滑肌细胞分离培养,待细胞融合度达约80%时进行传代,得到的内皮细胞利用差速消化法纯化,并观察2种细胞形态特征及培养特性,待细胞稳定生长后,采用荧光免疫组化技术鉴定细胞,并进行冻存和复苏,观察复苏后细胞活性。结果显示:24 h后组织块周围即有少量细胞爬出,内皮细胞大量生长后呈突起状排列,立体感强,平滑肌细胞在培养后的第5天呈现"峰谷"样外观,经免疫荧光法证明是内皮细胞和平滑肌细胞的纯培养,冻存于液氮中1~2个月复苏后细胞的活性都较好,可以恢复旺盛生长。结论:本研究提出的组织贴块法能成功获得内皮细胞和平滑肌细胞的纯培养,比酶消化法操作简单,更适合小血管内皮细胞、平滑肌细胞的原代培养。