title: Human ribosomal DNA fragments amplified in hamster cells are transcribed only by RNA polymerase II and are not silver stained.
abstract: Cloned human rRNA gene fragments that included the promoter region were introduced into Chinese hamster dihydrofolate reductase-deficient (dhfr-) cells by cotransformation with a dhfr minigene and amplified by selection for methotrexate resistance. The human ribosomal DNA was transcribed by RNA polymerase II, not RNA polymerase I or III. The metaphase chromosome regions containing the transcriptionally active human ribosomal DNA failed to show silver staining.
mesh_terms: D000818:Animals; D006224:Cricetinae; D003412:Cricetulus; D004275:DNA, Ribosomal / Q000235:genetics*; D005784:Gene Amplification; D006801:Humans; D011401:Promoter Regions, Genetic; D012319:RNA Polymerase II / Q000235:genetics*; D012834:Silver; D013194:Staining and Labeling; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D004275:DNA, Ribosomal; D012834:Silver; D012319:RNA Polymerase II