title: Evidence that progression of cells into S-phase is not a prerequisite for recovery between split doses of U.V.-light in synchronized and plateau phase cultures of Ehrlich ascites tumour cells.
abstract: The ability of Ehrlich ascites tumour cells (EAT-cells) to perform split-dose recovery after U.V. exposure was studied with unfed plateau phase as well as with synchronized cells selected from exponentially growing cultures. The cells were kept in balanced salt solution which inhibited the progression of the cells through the cell cycle. The results indicated that split-dose recovery occurred in EAT-cells in all phases of the cell cycle and that progression of the cells into S-phase was not a prerequisite for this type of repair. The second-dose survival curves of G1- and S-phase cells showed, 24 hours after the first U.V. exposure, a shoulder width comparable to that of singly irradiated cells. Second-dose survival curves for G2-cells showed, after the same time interval, a shoulder width smaller than that for singly exposed cells, presumably due to some cell division. The recovery time constant (t50 between 4 and 8 hours) increased with increasing U.V. exposure.
mesh_terms: D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000473:pathology*; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects*; D004260:DNA Repair; D066298:In Vitro Techniques; D007399:Interphase; D051379:Mice; D013997:Time Factors; D014466:Ultraviolet Rays