Studies on the structure of avian myeloblastosis virus (AMV) RNA. I. Factors affecting electron microscopic visualization of AMV RNA.

Factors affecting the visualization of single-stranded (ss) avian myeloblastosis virus (AMV) RNA by the basic protein film technique under strong denaturation conditions were studied. The basic parameters of the electron microscopic picture of ss RNA, involving the visibility, concentration and contour lengths of molecules, were found to be significantly dependent on the (1) quality of denaturing components used for full extension of AMV RNA molecules and (2) spreading and formation of the surface film. Under the conditions used, the presence of artificial secondary structures of AMV RNA molecules were dependent on batches of formamide and urea in the denaturing mixture. The spreading and formation of the surface film were affected by hydrophilicity of glass spreading ramps, speed of spreading, amount of spreading solution, amount of protein in the hyperphase, type of cytochrome c and the presence of substances influencing surface tension. The optimal conditions and spreading arrangement for visualization of ss AMV RNA are described.