An Electron Microscope Study of Sindbis Virus RNA (original) (raw)

1. Ming-ta Hsu,
2. Hsing-Jien Kung, and
3. Norman Davidson
4. Department of Chemistry, California Institute of Technology, Pasadena, California 91109

Excerpt

We wish to describe electron microscope methods for measuring the molecular lengths of RNA molecules and of mapping any poly(A) sequences present. We chose to apply these methods initially to Sindbis virus RNA.

The virion of Sindbis virus contains only 42 S RNA (Pfefferkorn et al., 1967) with a molecular weight of 4.3 ± 0.3 × 106 daltons, as estimated by DMSO sedimentation and gel electrophoresis (Simmons and Strauss, 1972). Sindbis RNA contains a poly(A) sequence (Johnston and Bose, 1972a, b). For most of the molecules, its length is 60 to 80 nucleotides; for a small fraction (20% or less), the length is 150–250 nucleotides (Eaton and Faulkner, 1972).

In general, the basic protein film electron microscope techniques that work very well for both duplex and single-stranded DNA are less effective for RNA. The Standard spreading conditions of 40 to 50% formamide and ca. 0.06 m ionic strength (Davis et...