Electron Microscopic Observations on the Ribonucleic Acid Molecules of Linear Structure in Rous Sarcoma Virus-induced Mouse Ascites Sarcoma Cells

The RNA extracted from Rous sarcoma virus (RSY)induced mouse ascites sarooma cells (SR·C3H, N. P.) by means of the cold SDS-phenol was examined by the electron microscopy on the specimens spread wi th or wi thout urea according to the protein mono· layer technique. The majority of RNA molecules was found in a collapsed agglomerated form, derived from matured ribosomal RNA. Using sucrose gradient, linear molecules of RNA were observed in the interspace of the agglomerated form of RNA at the region of high molecular weight of the band sedimentation. The histogram of the distribution in length of the linear molecules involved up to 6 /1 in length wi th a modal length of 2. 28 f1 and 2.0 to 2. 2 f1 in a pro. minent peak; longer molecules up to 18 f1 in length were scarcely observed. Species of the linear RNA molecules is not exactly known, although this is not mature ribosomal RNA and likely to be messenger RNA or nascent RNA molecules, some of which might associate with RSY·RNA.