[Nonprecipitability of the nucleic factor in the ultracentrifugation of tumor ascitic fluid].

Samples of cell-free ascitic liquid of mice and rats suffering from Ehrlich tumor and Zajdela's hepatoma, respectively, were centrifuged at 70,000 g and 200,000 g for 1 hour. Nucleic acid preparations were then isolated by phenol deproteinization and analysed by 8% polyacrylamide gel electrophoresis with subsequent densitometry. Under such conditions, DNA of nucleic factor as well as minor RNA fractions failed to precipitate. These results show that viral particles, tumor cell-produced vesicles and other large complexes do not incorporate DNA nucleic factor or minor RNA fractions.