Stimulated and non-stimulated rat spleen cells release different DNA-complexes

Isolated rat spleen cells released into the culture medium a complex containing newly-synthetized DNA. Upward sucrose density gradient centrifugation yielded material from non-stimulated cells at a major peak of density 1.03, with minor peaks at 1.04 and 1.055. However, the complex from cells stimulated with phytohaemagglutinin showed a major peak at 1.052, with little material at 1.03. The low densities indicated that the complexes contained a high proportion of lipid, confirmed by the incorporation of 3H-ethanolamine. Data indicate that newly synthesized DNA leaves the nucleus, crosses the cytoplasm, and associates with the cell membrane prior to leaving the cell as a complex with the DNA protected against nuclease activity.