Axel-Claude Garapin

RNA-directed DNA synthesis by virions of Rous sarcoma virus: Further characterization of the templates and the extent of their transcription☆

Abstract Four species of RNA found in Rous sarcoma virus have been tested for their roles as templates for RNA-directed DNA synthesis by detergent-activated virions of RSV: the high molecular-weight subunits of the 70S RNA complex, 4S and 5S RNAs contained in the 70S complex, and 7S RNA extracted from purified virions. All three forms of low molecular-weight RNA are at least partially transcribed, but the principal templates for DNA synthesis are the high molecular-weight subunits of 70S RNA. DNA synthesized by virions of RSV contains nucleotide sequences representative of most or all of the viral genome, but the majority of these sequences are present in very small proportions. These results further substantiate the occurrence of preferential transcription from a limited region of the viral genome as defined previously for double-stranded enzymatic product by measurement of reassociation kinetics. By contrast, single-stranded DNA synthesized by virions of RSV in the presence of actinomycin D is a complete and relatively uniform copy of the entire viral genome. The latter observation facilitates both the study of nucleic acid homologies among RNA tumor virus genomes and the execution of competition hybridizations to determine the portion of a viral genome present in various populations of cellular RNA. An example of each of these procedures is given.

Identification of virus-specific RNA in cells infected with rous sarcoma virus

Abstract The cytoplasm and nuclei of cells infected with Rous sarcoma virus contain RNA which can be annealed to single-stranded DNA synthesized by the RNA-dependent polymerase of the virus. Formation of DNA:RNA hybrids was detected by equilibrium centrifugation in Cs 2 SO 4 , and by step-wise elution from hydroxy-apatite. RNA which contains nucleotide sequences identical to those of the viral genome constitutes approximately 0.5% of the total RNA extracted from infected cells.