amanitins and Cell-Transformation--Neoplastic

Topics: Actins; Amanitins; Animals; Cell Adhesion; Cell Movement; Cell Transformation, Neoplastic; Contractile Proteins; Cytoskeleton; Endothelium; Fibroblasts; Fluorescent Antibody Technique; Humans; Microscopy, Electron; Morphogenesis

Highly purified and physiologically active nuclei were isolated from four different octopine and nopaline crown gall lines. These nuclei exhibited a high endogenous RNA synthesizing activity involving all three RNA-polymerases I, II and III. Isolated nuclei were shown by Southern blotting to synthesize T-DNA specific RNA. This synthesis was shown to be sensitive to actinomycin D and therefore to be DNA-dependent. The transcription of the T-DNA was also inhibited for more than 90% by low concentrations of alpha-amanitin (0.7 micrograms/ml) indicating that the T-DNA, although from bacterial origin, is transcribed by the host RNA polymerase II.

Topics: Amanitins; Base Sequence; Cell Transformation, Neoplastic; Dactinomycin; DNA; DNA-Directed RNA Polymerases; Nucleic Acid Hybridization; Osmolar Concentration; Plant Tumors; Plasmids; RNA; Transcription, Genetic

Topics: Amanitins; Animals; Cell Cycle; Cell Transformation, Neoplastic; Cells, Cultured; DNA; Embryo, Mammalian; Fluorouracil; Interphase; Methylcholanthrene; Mice; Poly A; Polyribosomes; RNA; RNA Polymerase II

Chick embryo cells transformed by Rous sarcoma virus (RSV) continue to synthesize 40--50 percent of control amounts of RNA following 12--24 hour exposure to 2 microng/ml of the toxin whereas normal chick embryo cells similarly treated synthesize less than 5 percent of control amounts of RNA. Analysis of cells treated with alpha-amanitin, or the resistant forms I and III polymerase, do not increase in infected cells over the levels found in uninfected control cells during the first 24 hours following infection indicating that increase in polymerase levels in infected cells does not account for the observed resistance. No significant difference was detected in the sensitivity to alpha-amanitin in the form II polymerase isolated from normal and transformed cells; The greater sensitivity of normal cells to alpha-amanitin can be reduced by growing the cells at low cell density but the resistance of RSV transformed cells is not significantly altered by changes in cell density. The results suggest that the resistance of RSV transformed cells may be related to altered control of density dependent contact-inhibition of the transformed cells.

Topics: Amanitins; Animals; Avian Sarcoma Viruses; Cell Division; Cell Nucleus; Cell Transformation, Neoplastic; Chick Embryo; Culture Techniques; DNA-Directed RNA Polymerases; Drug Resistance; RNA; RNA, Neoplasm

Topics: Amanitins; Cell Line; Cell Nucleus; Cell Transformation, Neoplastic; Interferons; RNA, Viral; Simian virus 40; Transcription, Genetic

Topics: Amanitins; Animals; Avian Sarcoma Viruses; Cell Fractionation; Cell Line; Cell Transformation, Neoplastic; Centrifugation, Density Gradient; Chick Embryo; DNA-Directed RNA Polymerases; Fibroblasts; Isoenzymes; RNA, Messenger; RNA, Neoplasm; RNA, Ribosomal; RNA, Viral; Tritium; Uridine; Virus Replication

DNA-dependent RNA polymerase (EC 2.7.7.6) ACTIVITIES FROM NORMAL BHK-21/C13 cells and from BHK-21/C13 cells transformed by polyoma virus (PYY cells) were solubilized and fractionated on columns of DEAE-Sephadex. Various properties of the A and B enzymes from the two types of cell were compared. 1. The yields of polymerase relative to the DNA content of the nuclear preparations are similar for both cell types. 2. The ionic-strength optima of polymerases A and B are 12.5 mM and 100mM with respect to (NH4)2SO4 for both cell types. 3. The Mn2+/Mg2+ activity ratio (measured at the respective optimum for each cation) for polymerase A from BHK-21/C13 cells was 1.48 and for the polymerase A from PYY cells was 0.55. The corresponding ratios for polymerase B were 10.11 for BHK-21/C13 cells and 22.75 for PYY cells. 4. Minor differences in the ability of the A polymerases to transcribe native and denatured DNA templates were observed; such differences were not apparent when the B polymerases were compared. 5. All the polymerases were inhibited completely by actinomycin D and by rifampicin AF/013, but not markedly so by rifampicin. Alpha-amanitin inhibited polymerase B but not polymerase A.

Topics: Amanitins; Ammonium Sulfate; Animals; Cell Line; Cell Transformation, Neoplastic; Cricetinae; Dactinomycin; DNA; DNA-Directed RNA Polymerases; Kidney; Magnesium; Manganese; Polyomavirus; Rifampin; Templates, Genetic