Tobacco Mosaic Virus Ribonucleic Acid Research Articles

Properties of infectious ribonucleic acid preparations obtained from tobacco mosaic virus by a heat method

A method is described for obtaining ribonucleic acid preparations from tobacco mosaic virus by a brief heat treatment. Such preparations are several times more infectious than previously reported tobacco mosaic virus ribonucleic acid preparations. This level of infectivity, nevertheless, is still low in comparison with natural or reconstituted tobacco mosaic virus. The infectious agent in these preparations differs from tobacco mosaic virus with respect to a number of physical, chemical, and biological characteristics which suggest that a high molecular weight ribonucleic acid is necessary for the infectivity of these preparations. Fractionation of ribonucleic acid preparations by elution from columns of Ecteola or by ultracentrifugation indicates that most of the infectivity in these preparations is associated with only a portion of the ribonucleic acid present. This, and the presence of about 0.5% protein in the RNA preparations, allows the possibility that ribonucleic acid may not be a self-sufficient agent of infection. The infectivity of both tobacco mosaic virus and ribonucleic acid preparations from the virus was found to depend on the total ionic strength of the inoculating medium, the pH, and the presence of phosphate. On the local lesion host Nicotiana glutinosa L., the optimum total ionic strength for infectivity of ribonucleic acid preparations was twice that for optimum tobacco mosaic virus infectivity.

Configurational properties of tobacco mosaic virus ribonucleic acid

The configuration of nearly monodisperse tobacco mosaic virus (TMV) ribonucleic acid (RNA) of molecular weight 2·0 ± 0·1 million was studied at 20 to 25°C in 0·1 M-sodium phosphate buffer, pH 6·8, by light scattering, sedimentation, viscosity, optical rotary dispersion, and optical absorbance measurements. Results show that the partly helical configuration stable under these conditions behaves hydrodynamically as a randomly coiled polymer chain. The RNA chain becomes more compact when solutions are heated briefly to temperatures as high as 80°C and cooled rapidly, or allowed to stand at 25°C for 2 days, no change in molecular weight or distribution being observed under these conditions.

An oligonucleotide mapping procedure and its use in the study of tobacco mosaic virus nucleic acid

A two-dimensional procedure was developed employing paper electrophoresis and paper chromatography, which permitted the separation and identification of all major products obtained by digestion of tobacco mosaic virus ribonucleic acid (TMV-RNA) with pancreatic ribonuclease. The map so obtained showed nineteen spots accounting for approximately 90 % of the optical density of the material applied. The substances in the major spots were quantitatively estimated by elution and spectrophotometry, and qualitatively identified by application of standard procedures for determining the composition of nucleotides and oligonucleotides. The homogeneities of the isolated compounds were evaluated by elution and subjection of eluates to ion-exchange and paper-chromatographic procedures.