Growth characteristics of anaerobically treated early and late S-period of Ehrlich ascites tumor cells after reaeration.

Utilizing centrifugal elutriation, early and late S-phase cells were separated from 4, 8 and 12 h anaerobically cultured Ehrlich Ascites tumor cells strain Karzel. The cytokinetic properties of these fractions after reaeration were studied by flow cytometry and the BrdU-H 33258-technique of flow cytometry. After a 4 h period of anaerobiosis, growth of early S-phase cells is not changed, 8 h deprivation of oxygen causes a delay of cell cycle progression, while the main fraction of 12 h anaerobically treated early S-populations did not divide after reaeration within 24 h. In comparison to early S-phase cells the cell cycle progression of the main fraction of late S-period is accelerated after a 4 h exclusion of oxygen. A fraction of 8 h anaerobically pretreated late S-cells continues to cycle, but a considerable number reinitiates DNA synthesis without preceeding division. Cells with DNA content up to 8 c are detected by flow cytometry. 12 h anaerobically cultured late S-cells do not divide after reaeration, a large number of these cells starts again to synthesize DNA. A considerable part of tetraploid cells retain viability, divide and enter a new cell cycle, another part of the cells disintegrates.