| Abstract: | A fraction defined as the inclusions was isolated by banding in CsCl gradients from nuclei of adenovirus 12-infected KB cells. When examined by electron microscopy, the isolated inclusions were relatively homogeneous, finely granular materials of moderate electron density, possibly representing the disintegrated type II or IV inclusions. The conditions of endogenous DNA synthesis in vitro with the inclusions were determined. The product of DNA synthesis in vitro with the inclusions was mainly viral and scarcely cellular, as revealed by DNA-DNA hybridization and methylated albumin kieselgur column chromatography. However, viral DNA synthesized in vitro was smaller (18 S, 22 S) than viral DNA in virions (31 S, 34 S) in neutral and alkaline sucrose gradients. Effects of various treatment of the inclusions on the DNA-synthesizing activity showed that phospholipase C inhibited the activity efficiently. The in vitro DNA synthesis was stimulated by addition of the cytoplasmic extract from adenovirus 12-infected cells and not that from unifected cells. The analysis of the composition of the inclusions showed that the inclusions contained DNA, protein, phospholipid and a small amount of RNA and carbohydrate. |
