期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1977
卷号：74
期号：10
页码：4233-4237
DOI：10.1073/pnas.74.10.4233
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Many repeating units of Drosophila melanogaster rDNA contain a DNA sequence within the gene for 28S rRNA that does not code for rRNA. This sequence has been called the ribosomal insertion [Wellauer, P. K. & Dawid, I. B. (1977) Cell 10, 193-212]. We report here that members of the same sequence family occur outside the ribosomal locus. "Non-rDNA insertion DNA" was separated from rDNA by density gradient centrifugation, and sequences homologous to the ribosomal insertion were detected by hybridization with restriction endonuclease fragments derived from a cloned rDNA repeating unit. Pure insertion sequences from cloned rDNA separated from main band DNA and behaved like a component with high G + C content. Non-rDNA components hybridizing to the insertion also separated from main band DNA but less so than pure insertion sequences, suggesting that non-rDNA insertion sequences are linked to DNA of different nucleotide composition. Restriction endonuclease analysis of non-rDNA insertion DNA showed many fragments of different sizes. The patterns obtained were similar in embryonic, larval, pupal, and adult DNA and DNA from cultured cells (Schneider cell line 3). Non-rDNA insertion sequences account for about 0.2% of the genome or about 400 kbases of DNA per haploid complement.
关键词：ribosomal DNA ; rRNA ; Drosophila melanogaster ; density gradient centrifugation ; repetitive sequence families
