The Structure and Characterization of a Closterovirus, Beet Yellows Virus, and a Luteovirus, Beet Mild Yellowing Virus, by Scanning Transmission Electron Microscopy, Optical Diffraction of Electron Images and Acrylamide Gel Electrophoresis

Attempts were made to determine more precisely the structure and properties of a closterovirus, beet yellows virus (BYV), and a luteovirus, beet mild yellowing virus (BMYV), by scanning transmission electron microscopy, optical diffraction of electron images and acrylamide gel electrophoresis. It was shown that BYV has a mol. wt. of 76.5 x 10⁶, including an RNA of 4.15 x 10⁶. The pitch of the helix is 3.7 nm and there would be 8.5 protein subunits per turn. BMYV particles have a diameter of 26 nm and a total mol. wt. of 6.5(±0.45) x 10⁶. The mol. wt. of the protein subunit is about 24000 and that of the RNA 2 x 10⁶.