Studies on the intracisternal A-type particles in mouse plasma cell tumors: induction of maturation of the particles.
Maturation of the intracisternal A-type particle found in two mouse plasma cell tumors was induced by treating the cells in culture with IDU-DMSO or with DMSO only. Morphologically, the mature particles with electron-dense nucleoids closely resembled the mature particles described in human tumor cell lines treated in a like manner. They also closely resembled the virus that has been described in guinea pig leukemias. It was not possible to demonstrate infectivity of the mature particle, as latent intracisternal A-type particles induced by IDU were found in the mouse cells presumed to be free of virus. The biochemical studies did not show distinct new peaks of virus-specific particles in sucrose density gradients when the particles in the treated cells were compared with the particles of the untreated cells. There was a difference in the density of the particles observed in the induced cells (1.2) and those of the control cells (1.185). This may reflect the difficulty of separating mature and immature particles. Analysis of the RNA present in the particles showed that the ratio of heavy-molecular-weight RNA in activated cells to the predominant species (21S) is much greater than that in control cells. Detectable levels of enzyme activity were not found in the induced particles. This could be due to too low a concentration of particles in the preparations.
D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D004121:Dimethyl Sulfoxide / Q000494:pharmacology*; D007065:Idoxuridine / Q000494:pharmacology; D051379:Mice; D008854:Microscopy, Electron; D010954:Plasmacytoma; D014779:Virus Replication / Q000187:drug effects*; D014780:Viruses / Q000302:isolation & purification
D007065:Idoxuridine; D004121:Dimethyl Sulfoxide