title: Nucleolar ultrastructure and transcription of preribosomal RNA in Rous sarcoma virus-transformed chick embryo fibroblasts treated with alpha-amanitin.
abstract: Uninfected and Rous sarcoma virus (RSV)-transformed chick embryo fibroblasts (CEF) were exposed to various concentrations of alpha-amanitin for different lengths of time. At a concentration of 4 micrograms alpha-amanitin/ml, RSV-transformed cells were shown to maintain a normal rate of transcription of all classes of RNA, whereas in uninfected cells transcription was reduced to a very low level. These observations cannot be accounted for by a difference in the penetration rate of alpha-amanitin through the plasma membrane. Investigation of the ultrastructure showed that the degree of nucleolar fragmentation induced by alpha-amanitin was comparable in both types of cells. Persistence of transcription with concomitant nucleolar fragmentation in alpha-amanitin-treated RSV-transformed CEF is not in accord with the hypothesis that nucleolar integrity is required for preribosomal RNA transcription.
mesh_terms: D000546:Amanitins / Q000494:pharmacology*; D000818:Animals; D001358:Avian Sarcoma Viruses; D002466:Cell Nucleolus / Q000648:ultrastructure*; D002472:Cell Transformation, Viral; D002478:Cells, Cultured; D002642:Chick Embryo; D008854:Microscopy, Electron; D009694:Nucleic Acid Precursors / Q000096:biosynthesis; D012335:RNA, Ribosomal / Q000096:biosynthesis*; D014158:Transcription, Genetic
chemical_list: D000546:Amanitins; D009694:Nucleic Acid Precursors; D012335:RNA, Ribosomal