Transcription Fidelity and Structural Integrity of Isolated Nucleoli

Publisher Website
Google Scholar
Abstract
RNA was transcribed in vitro using isolated [rat liver] nucleoli, the endogenous form A RNA polymerase [EC 2.7.7.6] and mercurated UTP as one of the nucleoside triphosphate substrates. The products were isolated from endogenous nucleolar RNA sequences by chromatography on sulfhydryl-Sepharose and analyzed by hybridization in vast DNA excess. The results of competition-hybridization experiments suggested that a large proportion of the transcript was rRNA although some sequences were transcribed from DNA of lower reiteration frequency. Analyses of the constituents of nucleoli following isolation by the sonication procedure suggested that the nucleolar DNA, particularly the ribosomal cistrons, are severely degraded. The transcription complexes were probably damaged and many of the nascent RNA chains were probably sheared from near the growing points.