ELECTRON-MICROSCOPE STUDIES OF TUMOR-VIRUS RNA
ELECTRON-MICROSCOPE STUDIES OF TUMOR-VIRUS RNA
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DOI：
10.1101/sqb.1974.039.01.096
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发表时间：
1974-01-01
期刊：
影响因子：
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通讯作者：
MCALLISTER, RM
中科院分区：
文献类型：
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作者：
KUNG, HJ;BAILEY, JM;MCALLISTER, RM
从病毒体中提取的RNA肿瘤病毒的RNA的主要成分是一种复合物，在60- 70 S处沉淀，估计分子量约为107道尔顿。当经受变性条件时，该复合物解离，得到沉降系数为~ 35 S的几个大组分和沉降系数在4- 10 S范围内的一些低分子量组分。这几种大小组分的凝胶电泳迁移率与根据其沉降系数估计的分子量一致（Temin 1974; Bolognesi 1974）。电子显微镜有可能成为一种有用的物理方法，用于研究60- 70 S复合物的分子结构及其组成的几个亚基。我们在这里报告我们的几个肿瘤病毒的RNA的初步研究。我们特别关注的是大（-35S）亚基的长度测量，以及可能出现在单个70 S复合物中的两个或三个大亚基的序列是相同的还是不同的问题。在碱性蛋白膜技术的甲酰胺修饰中，使用由50%甲酰胺和0.1 M Tris支持电解质组成的铺展溶液，G+ C含量小于约60%的DNA单链表现为光滑、良好延伸的细丝（Davis等，1971）。在相似的铺展条件下，具有相似碱基组成的RNA分子倾向于多节、粗而短。（1973）;该方法最近已用于肿瘤病毒RNA的研究（Delius等人，该体积）;（B）由Hsu等描述的甘氨酸-甲酰胺技术。（1973）（还参见Forsheit等人，1974）;（c）Robberson等人描述的低电解质浓度下的脲-甲酰胺扩散溶液。（1971）和Wellauer和Dawid（1973）;这种技术似乎对于揭示RNA和DNA分子中某些稳定的二级结构特征特别有效。在本研究中，我们使用了方法（B）和（c）。
The principal component of the RNA of RNA tumor viruses, as extracted from the virion, is a complex which sediments at 60-70S and is estimated to have a molecular weight of approximately 107 daltons. When subjected to denaturing conditions, this complex dissociates to give several large components with sedimentation coefficients of-35S and some lower molecular weight components with sedimentation coefficients in the range 4-10S. The mobilities in gel electrophoresis for these several large and small components are consistent with molecular weight estimates from their sedimentation coefficients (Temin 1974; Bolognesi 1974). Electron microscopy has the potential of being a useful physical method for the study of the molecular structure of the 60-70S complex and of the several subunits of which it is composed. We report here on our initial studies of the RNA of several tumor viruses. We have been particularly concerned with length measurements of the large (-35S) subunits and with the question of whether the two or three large subunits that probably occur in a single 70S complex are identical in sequence or different. In the formamide modification of the basic protein film technique, using a spreading solution consisting of 50% formamide and 0.1 M Tris supporting electrolyte, single strands of DNA with a G+ C content of less than about 60% appear as smooth, well-extended filaments (Davis et al. 1971). Under similar spreading conditions, RNA molecules of similar base composition tend to be knobby, thick and short.Several modified techniques are useful for spreading RNA molecules:(a) the gene 32 procedure of Delius et al.(1973); this method has recently been used for studies of tumor virus RNA (Delius et al., this volume);(b) the glyoxal-formamide technique described by Hsu et al.(1973)(see also Forsheit et al. 1974);(c) the urea-formamide spreading solution at low electrolyte concentration described by Robberson et al.(1971) and Wellauer and Dawid (1973); this technique appears to be particularly effective for revealing certain kinds of stable secondary structure features in RNA and DNA molecules. In the present studies, we have used methods (b) and (c).