STUDIES ON THE FORMATION OF TOBACCO MOSAIC VIRUS RIBONUCLEIC ACID, III. UTILIZATION OF RIBONUCLEOSIDES OF HOST RIBONUCLEIC ACID

Abstract

The radio-activities of tobacco mosaic virus (TMV)-RNA and microsomal RNA, isolated from infected tobacco leaves grown in the presence of p32, were determined. The specific radioactivity of TMV-RNA is more than four times that associated with microsomal RNA. The specific radioactivities of four mononucleotides, obtained by the digestion of p32-TMV-RNA with alkali and snake venom phosphodiesterase, are similar. Furthermore, the distribution of radioactive label in the entire molecule of TMV-RNA is remarkably uniform. Hence, the phosphate moiety of TMV-RNA is not derived from the microsomal RNA. On the basis of the results presented in this paper and the previous publication of this series, it is concluded that only the ribonucleoside moieties of microsomal RNA are utilized in the synthesis of TMV-RNA.