Difference in sedimentation profiles on DNA from various cell types during lysis periods by direct alkaline sucrose...

Sedimentation condition for DNA from various kinds of cultured mammalian cells lysed directly on the top of an alkaline sucrose gradient was examined after the lysis for various periods at 19 degrees or 37 degrees. When cultured normal embryo cells from human, mouse, and Syrian hamster were analyzed, "complex" and "main" peaks were demonstrated. The former, which had low sedimentation coefficient, was obtained after 1 or 2 hr of lysis at 19 degrees and resolved after a 4-hr lysis into the latter which had a higher sedimentation coefficient. When cultured cells with malignant history were analyzed, a sharp and high peak was observed after 1 or 2 hr of lysis of 19 degrees and this peak resolved into the "main" peak after a 4-hr lysis. When the cells were lysed at 37 degrees, the "main" peak appeared after 1 or 2 hr of lysis. Metaphase cells in which the chromatin is condensed heterchromatically were also analyzed. Sedimentation profiles from normal human embryo cells and HeLa cells in metaphase were similar to those obtained from cells with malignant history in interphase during various lysis periods. From these data the difference in the sedimentation pattern between normal embryo cells and cells with malignant history could be interpreted as a phenotypic expression of the cells.