title: Fidelity of ribosomal ribonucleic acid synthesis by nucleoli and nucleolar chromatin.
abstract: Isolated nucleoli, nucleolar chromatin, and nucleolar DNA were used as templates for DNA synthesis in appropriately supplemented systems in which RNA polymerases other than RNA polymerase I were blocked by alpha-amanitin. With the aid of nucleotide analysis, DNA-RNA hybridization, and homochromatography fingerprinting, it was found that isolated nucleoli and nucleolar chromatin serve primarily as templates for synthesis of rRNA. However, the products formed with purified nucleolar DNA as a template do not contain the specific rRNA oligonucleotides nor are they appreciably hybridized to the rDNA region on cesium chloride gradients. These results indicate that whole nucleoli and nucleolar chromatin contain control mechanisms that restrict readouts by RNA polymerase I of nucleolar DNA to rDNA.
mesh_terms: D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000378:metabolism; D002466:Cell Nucleolus / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism*; D007700:Kinetics; D008113:Liver Neoplasms / Q000378:metabolism; D009374:Neoplasms, Experimental / Q000378:metabolism; D009843:Oligoribonucleotides / Q000032:analysis; D012318:RNA Polymerase I / Q000302:isolation & purification / Q000378:metabolism; D012335:RNA, Ribosomal / Q000096:biosynthesis*; D051381:Rats; D006163:Ribonuclease T1; D014158:Transcription, Genetic
chemical_list: D002843:Chromatin; D009843:Oligoribonucleotides; D012335:RNA, Ribosomal; D012318:RNA Polymerase I; D006163:Ribonuclease T1