title: Inhibition of initiation of HeLa cell replicons by methyl methanesulfonate.
abstract: Methyl methanesulfonate (MMS) in the culture medium inhibits the rate of DNA synthesis in HeLa cells in a dose-dependent manner. By using short (5 min) incubations with [3H]thymidine and analyzing the newly made DNA by velocity sedimentation on alkaline sucrose gradients, we found that the first affect of MMS on DNA replication, at 0.5 h after treatment, was inhibition of initiation of replicons. Recovery from this effect seemed to have begun by 2 3/4 h after treatment. The second effect of MMS, which was evident at 2 h after treatment, was to slow or block chain elongation.
mesh_terms: D002499:Centrifugation, Density Gradient; D004261:DNA Replication / Q000187:drug effects* / Q000528:radiation effects; D006367:HeLa Cells / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D008698:Mesylates / Q000494:pharmacology*; D008741:Methyl Methanesulfonate / Q000494:pharmacology*; D008970:Molecular Weight
chemical_list: D008698:Mesylates; D008741:Methyl Methanesulfonate