The interaction of tritium-labelled Mengo virus RNA and L cells: The effects of DMSO and DEAE-dextran

Abstract

DMSO and DEAE-D have been shown to stimulate the formation of infectious centers when added to media in which L cells and Mengo RNA are incubated. As part of a continuing investigation of the effects of these additives on cell-RNA interaction, their effects on the uptake of 3H-labelled viral RNA by L cells were examined. Viral RNA was isolated by a modified phenol technique from highly purified Mengo virus which had been propagated in L cells in the presence of actinomycin D and uridine- 3H. The uptake of radiolabel by L cells was measured after their incubation with 3H-labelled viral RNA in PBS, in 0.6 M sucrose/PBS, in 0.6 M sucrose/PBS-10% DMSO, and in PBS containing 100 μg DEAE-D per milliliter. Extremely small quantities of RNA are taken up by cells incubated in 0.6 M sucrose/PBS, and the uptake is not increased by the presence of DMSO in the incubation medium. More RNA is taken up by cells incubated in PBS than by cells incubated in either of the sucrose media examined, and the presence of DEAE-D in the medium produces a striking increase in the amount of RNA that becomes firmly cell associated. Most of the RNA that becomes cell associated during incubation in PBS and the two sucrose media remains so after incubation of the cells with pancreatic ribonuclease, whereas approximately 90% of the RNA that is bound to cells in the presence of DEAE-D is removed by a brief exposure to this enzyme.