title: The rate of deoxyribonucleic acid synthesis by cultured Chinese-hamster ovary cells. An application of isotope-dilution analysis.
abstract: The rate of DNA synthesis is exponentially growing cells was determined by isotopedilution analysis of the incorporation of [me-3H]thymidine. Thymidine concentrations greater than 7 micrometer were used so that the rate-limiting step governing incorporation would be at the level of DNA polymerase rather than at the level of thymidine kinase [Sjostrom & Forsdyke (1974) Biochem. J. 138, 253-262]. In early exponential phase the rate determined by isotope-dilution analysis closely correlated with the rates calculated either from growth curves or from known cell-cycle parameters. However, in late-exponential phase the rate calculated from the growth curve was less than that determined by isotope-dilution analysis. We conclude that, under certain conditions, the pool-corrected rate of incorporation of [me-3H]thymidine, as determined by isotope-dilution analysis, can accurately reflect the rate of DNA synthesis. Discrepancies between the observed rate of DNA synthesis and increase in cell number could reflect an exponential degeneration of post-S-phase cells.
mesh_terms: D002455:Cell Division; D002478:Cells, Cultured / Q000378:metabolism*; D004247:DNA / Q000096:biosynthesis*; D007700:Kinetics; D011865:Radioisotope Dilution Technique; D013936:Thymidine / Q000378:metabolism
chemical_list: D004247:DNA; D013936:Thymidine