Origin from Mitochondria of the Double-walled Viral Membrane in Saccharomyces

Abstract

INVESTIGATION of the viral infections of Saccharomyces^1,2 has shown that this organism is parasitized by both a rod-shaped virus (like tobacco mosaic virus) and a double-walled, spherical, nucleoid virus. Electron microscopy, in this laboratory, on the ætiology of yeast infection has been carried out on strains affected by the spherical, double-walled, nucleoid virus³. Electron micrographs show that the site of propagation of the virus is the mitochondrion and that the outer double wall of the virus is derived from the double-walled cristæ of the mitochondrion. Fig. 1 shows the mitochondria of a normal yeast cell. Fig. 2 shows a focus of viral infection multiplying at a centre from which three double-walled cristæ of a disrupted mitochondrion radiate into the cytoplasm. In this cell (and in Fig. 3) there are three mitochondrial foci in which the walls of the mitochondria have become sinuous and are enveloping the viral particles. In Fig. 4 viral particles are found within disintegrated mitochondria. Fig. 5 shows a cell in which the protoplast has been transformed into virus particles and membranes.