Visualization of single-stranded nucleic acid of RNA tumor virus with the electron microscope

60-70S RNA of avian myeloblastosis virus was spread with the Kleinschmidt method and examined in the electron microscope after being subjected to a variety of denaturing conditions. Extension of the molecules from a collapsed configuration was seen only under stringent denaturing conditions, resulting in molecules of 1-2 mum in length. Longer strands of these extremely fragile molecules cannot be obtained with the methods presently available.