DNA与RNA谁是主角?

DNA与RNA相伴而生,是一对孪生分子。生命起源最早出现可能是“核酸世界”,DNA与RNA是后来分化产生的。在当今生命系统中,DNA、RNA和蛋白质起着决定的作用,成为生命系统中的三驾马车。RNA干扰的发现表明,生物基因表型的变化是受RNA控制的。RNA转录后复杂的加工过程反映了RNA的进化历程。因此,重新认识RNA已成为当前生命科学亟待解决的问题。     

细菌芽孢染色法的改良探索

文中对微生物学实验教材上介绍的Schaeffer-Fulton氏芽孢染色法进行了改进。用石碳酸复红试剂代替0.5番红水溶液作为复染剂,并对比不同石碳酸复红浓度及染色时间对染色效果的影响。结果表明,以石碳酸复红的10倍稀释液为复染剂,复染30 s~1 min时能达到最佳的染色效果。改进方法操作简单易行,染色效果对比鲜明,可使学生更易将菌体与芽孢区分开来。将改进的染色方法运用于微生物学实验教学,收到了良好的教学效果。     

聚乙二醇6000沉淀法提纯线粒体DNA

本文介绍一种纯化线粒体 DNA的新方法。提取线粒体总核酸后,采用 NaCl盐析法,将线粒体大分子RNA与线粒体DNA分开,得到线粒体DNA 粗制品。再用聚乙二醇6000沉淀法进行纯化,从而得到纯的线粒体DNA。 此方法与 Sepharose 4B柱层析及氯化铯—溴化乙锭密度梯度超速离心纯化线粒体DNA的方法比较,具有经济、简便的特点,同时还可分别得到大分子线粒体RNA及小分子线粒体RNA。用此法制备的线粒体DNA易于酶切。     

锌对大鼠脑区组织核酸含量的影响

通过测定大鼠不同脑区锌对RNA、DNA含量的影响,探讨锌对大鼠学习记忆作用的促进是否与RNA、DNA的合成有关.     

碱性强弱染色非变性聚丙烯酰胺凝胶对微卫星DNA检测效果的影响

非变性聚丙烯酰胺凝胶电泳常用于分离不同分子质量和空间构象的DNA或RNA等生物大分子，由于分辨率可以达到2个碱基对，因此非变性聚丙烯酰胺凝胶对于微卫星DNA有很好的检测效果。利用非变性聚丙烯酰胺凝胶电泳对黄牛微卫星DNA的检测表明：碱性强弱的控制对于染色的效果和效率有显著的影响。弱碱性环境下，具有背景浅、条带明显和检测...     

RUVBL2基因knock-down对Rad51和γ-H2AX foci的影响

用脂质体转染的方法将特定的RUVBL2 si RNA序列转染到真核细胞,并鉴定其在人肺纤维细胞(MRC5 SV)中的表达,以确保RUVBL2基因的knock-down效果。用Rad51和γ-H2AX的特异性抗体进行免疫荧光染色,应用荧光显微镜观察计数Rad51和γ-H2AX foci的数量。Western blot法证实了si RNA以及转染的效率,确定了RUVBL2基因的存在有利于诱导DNA双链断裂(DSB)条件下Rad51和γ-H2AX被招募到DNA损伤位点。     

通过DNA聚合剪切放大体系提高RNA的检测灵敏度

基于循环的DNA剪切循环放大分子机器构建了一个RNA传感器。该分子机器以RNA为输入,产生大量的DNA片段,并替换报告探针上的荧光DNA从而产生荧光信号,实现对靶RNA浓度的放大检测。本分子机器分为两部分,反应部分和报告部分。在反应部分,以靶RNA为输入条件,以一个特殊设计的探针为反应模板引发一个自发连续的DNA聚合-剪切反应网络,重复产生大量信号DNA链;这些信号DNA链进入报告部分,通过杂交替换反应从一个报告探针上替换下带有荧光DNA序列,释放到溶液中。这样通过剪切产生的大量DNA适体序列被释放到溶液中,并替换报告探针上的荧光DNA,实现信号的放大。     

病毒在生物进化中的重要意义

最早的原始 RNA 是地球上的第一批生命。逆转录 RNA 所产生的 DNA 是球上第一批以DNA 为遗传信息载体的生命祖先。当今的一切生物都重现着原始 RNA 的进化方式,即以基因的重排与重组作为产生物种多样化的手段。这些都可由当代病毒学的新发现中获得证据。     

DNA元素百科全书计划：将垃圾DNA的想法丢进垃圾堆

事情曾经很简单,由 DNA 产生 RNA,RNA 产生蛋白质。后来对调控基因、RNA 的加工以及其他细节有了更深入的了解。再后来是第一条 DNA 的序列使研究人员大吃一惊,因为真正编码蛋白质的基因是像散落在很呆板、明显无所事事的 DNA 布丁上的葡萄干一样分散的序列。这些无所事事的 DNA 是什么?是垃圾。     

苜蓿转化细胞系核酸和蛋白质合成的研究

以苜蓿转化细胞系和对照细胞系为材料，利用同位素标志方法研究了3种大分子物质－－DNA、RNA和蛋白质的合成动态。结果表明，与对照细胞系相比，转化细胞系的生长速度明显加快，DNA、RNA和蛋白质的合成旺盛，合成速度显提高。同时，转化细胞系DNA、RNA和蛋白质出现最大合成速度的时间均相应地延迟。     

PAG中RNA电泳区带的快速染色方法

本文对聚丙烯酰胺凝胶(PAG)中RNA电泳区带的亚甲兰染色,提出一种新方法,根据需要可在0.5或1～2小时内直接显带,无须背景脱色程序,染色灵敏度为10~(-8)g。     

山药总RNA不同提取方法的比较研究

为提取高质量的山药总RNA,以铁棍山药茎段为材料,采用Trizol法、RNAiso for Polysacchariderich Plant Tissue法、改良CTAB法和试剂盒法提取总RNA,利用琼脂糖凝胶电泳分析所提取RNA的完整性,并用超微量分光光度计分析RNA的纯度.结果显示采用Trizol法难以提RNA,RNAiso for Polysacchariderich Plant Tissue法提取效果不理想,存在DNA和蛋白质污染,而用改良CTAB法和试剂盒法提取到的总RNA纯度高、完整性好,其中,改良CTAB法较试剂盒法价格便宜,但提取过程较烦琐.因此,应根据实验需要选择CTAB法或试剂盒法提取铁棍山药总RNA.本结果对其他品种山药或富含多糖多酚类物质植物的RNA的提取也具有一定借鉴意义.     

Configuration of nucleolar DNAin situ in nucleolus ofAllium cepa cells

The location and configuration of nucleolar DNA have not been determined for a long time. In this paper, we have observed the nucleolar ultrastructure and the character of nucleolar DNA in Allium cepa cells by conventional electron microscopy and the cytochemical NAMA-Ur DNA specific staining method. Furthermore, we have properly improved the NAMA-Ur method so as to analyze the location and configuration of nucleolar DNA in situ. Our results indicated that the nucleolar DNA in Allium cepa cells is mainly located at the border between fibrillar centers and dense fibrillar component, especially distributed in the configuration of encircling the fibrillar centers.     

Role of RNA transcripts in replication incompatibility and copy number control in antibiotic resistance plasmid derivatives

The genes required for autonomous replication and incompatibility in the antibiotic resistance plasmids R100 and R1 have been located within a 2.5-kilobase region of the 90-kilobase genome, within which the incompatibility gene occupies a 1.3-kilobase region excluding the replication origin. We now report that three RNA species are synthesized in vitro from the 2.5-kilobase region, which R100 and R1 have in common. One, a long RNA molecule which is transcribed in the direction of DNA replication, probably acts as a messenger or a protein required for plasmid replication. The second RNA species, only 91 nucleotides long, is transcribed in the opposite direction, from a region of the DNA entirely contained within the first and known to specify incompatibility and copy control functions. The third RNA species, 150 bases long, is transcribed from a region including the replication origin; it may be a primer of DNA synthesis or, in conjunction with the second of the three RNA species, an influence in the control of replication.     

CTAB法提取动物DNA

针对实际操作中常用的动物基因组DNA提取方法所面临的一些不足,对CTAB法进行改进,将其运用于动物基因组DNA的提取。结果表明,改进后的CTAB法具有时间短、质量高、成本低的优点,与实验教学中植物DNA和RNA提取的方法相一致,使分子生物学教学用品一体化,价格低廉化,效果改进,是一个不仅可以用于研究,也可以大规模用于实验教学的好方法。     

Detection of single base substitutions in total genomic DNA

Certain single base substitutions causing genetic diseases or resulting in polymorphisms linked to mutant alleles, alter a restriction enzyme cleavage site and can therefore be detected in total genomic DNA using DNA blots. Many base substitutions do not lead to an altered restriction site, but these can be detected using synthetic oligonucleotides as hybridization probes if the DNA sequence surrounding the base substitution is known. In the case of beta-thalassaemia, where 22 different single base mutations have been identified, a large number of probes would be required for diagnosis. An approach which was used to detect mutations in viral DNA involves the S1 nuclease treatment of heteroduplexes formed between wild-type and mutant DNA. Although certain single base mismatches are cleaved by S1 nuclease (ref. 11 and T. Shenk, personal communication), many other mismatches examined by this procedure are not cleaved (B. Seed, personal communication; R.M.M., unpublished data). Heteroduplexes between mutant and wild-type subgenomic fragments of double-stranded reovirus RNA migrate slower than the corresponding homoduplexes in polyacrylamide gels containing 7 M urea, but it is not known whether this method is applicable to DNA heteroduplexes containing single base mismatches. Here we describe a procedure that involves the electrophoretic separation of DNA heteroduplexes in a well-characterized gel system. We show that four different human beta-thalassaemia alleles with known single base mutations can be detected with as little as 5 micrograms of total genomic DNA. The method should be useful in the localization and diagnosis of mutations associated with genetic diseases.     

细胞太空无源搭载装置中的微载体技术初步研究

探讨基于微载体技术的改良细胞单克隆化方法,及直接研究微载体上细胞形态、细胞增殖、核酸提取的方法。利用快速染色法直接观察微载体上的细胞形态,并用MTT法直接分析细胞增殖,用Trizol试剂和吸附柱直接从微载体提取细胞核酸。对微载体上的细胞可直接进行染色,观察正常细胞和凋亡细胞的形态。MTT分析显示细胞数和OD值呈直线关系。从微载体上直接提取的RNA完整性好,可用于RT-PCR分析,提取的DNA含量较高。改良细胞单克隆化方法操作简便,细胞活性好;不消化细胞,可以直接研究微载体上的细胞形态、细胞增殖,提取核酸。     

Selection in vitro of single-stranded DNA molecules that fold into specific ligand-binding structures.

We have isolated a set of ligand-binding DNA sequences from a large pool of random sequence DNAs by selection and amplification in vitro, using similar methods to those described for the isolation of ligand-binding RNAs. The ligand-DNA interactions are both sequence- and ligand-specific, and are dependent on proper folding of the single-stranded DNA. Some ligands led to the isolation of more DNA sequences than RNA sequences, and vice versa. Analysis of individual sequences reveals that ligand binding is DNA-specific; RNAs of identical sequence could not interact with the same ligands. Ligand-binding DNAs might be more suitable than RNAs as potential pharmacological reagents because of the greater stability of DNA. The apparent primacy of RNA in the early evolution of life may have been due to its availability rather than to its functional superiority.