• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Molecular and Cellular Biology >Transcription of mouse rDNA and associated formation of the nucleolus organizer region after gene transfer and amplification in Chinese hamster cells.
【24h】

Transcription of mouse rDNA and associated formation of the nucleolus organizer region after gene transfer and amplification in Chinese hamster cells.

机译：在中国仓鼠细胞中进行基因转移和扩增后，小鼠rDNA的转录和核仁组织区的相关形成。

获取原文
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Mouse rDNA can initiate transcription by using only Chinese hamster cell components, and this is associated with nucleolus organizer activity. To demonstrate this, we transferred a 3.2-kilobase segment of mouse rDNA containing the promoter, the transcription initiation site, and part of the external transcribed spacer to dihydrofolate reductase-deficient Chinese hamster cells by cotransformation with an abbreviated mouse dhfr gene. Stepwise selection for methotrexate resistance produced sublines in which the mouse rDNA was usually coamplified with the donor dhfr DNA and occupied the same site or sites in the hamster genome, as shown by in situ hybridization. Transcription from mouse rDNA was demonstrated in two such lines, and S1 protection mapping indicated faithful initiation of the transcript. In some cells from both lines, the chromosome segments containing amplified mouse rDNA showed multiple silver-staining regions (i.e., active nucleolus organizers). Although the transferred mouse rDNA was able to use the rDNA transcriptional machinery of the Chinese hamster, the level of transcription was much lower than expected from the rDNA copy number, and a large fraction of each amplified region showed no silver staining. Since the absence of silver staining is generally correlated with the absence of transcription, many copies of the amplified mouse rDNA may have been in a chromatin conformation in which they could not be transcribed. This was not associated with the extensive methylation seen in other amplified, inactive rDNA sequences.
机译：小鼠rDNA只能通过使用中国仓鼠细胞成分来启动转录，这与核仁的组织者活性有关。为了证明这一点，我们通过与小鼠dhfr缩写基因共转化，将包含启动子，转录起始位点和部分外部转录间隔子的小鼠rDNA的3.2千碱基片段转移到二氢叶酸还原酶缺陷的中国仓鼠细胞中。甲氨蝶呤抗性的逐步选择产生了亚系，其中小鼠rDNA通常与供体dhfr DNA共同扩增，并在仓鼠基因组中占据一个或多个相同位点，如原位杂交所示。小鼠rDNA的转录已在两条这样的谱系中得到证实，并且S1保护作图表明了转录的忠实起始。在来自这两个系的一些细胞中，含有扩增的小鼠rDNA的染色体区段显示出多个银染色区域（即，活性核仁组织者）。尽管转移的小鼠rDNA能够使用中国仓鼠的rDNA转录机制，但转录水平远低于从rDNA拷贝数预期的水平，并且每个扩增区域的大部分均未显示银染。由于银染的缺乏通常与转录的缺乏相关，因此扩增后的小鼠rDNA的许多拷贝可能处于染色质构象，无法转录。这与在其他扩增的非活性rDNA序列中看到的广泛甲基化无关。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号