β Scribed by John D. Schuetz; Hugh J. Wallace; Robert B. Diasio
No coin nor oath required. For personal study only.
5-Fluorouracil (FUra) was previously demonstrated to be incorporated into DNA at cytotoxic concentrations in mouse bone marrow cells. Subsequently, we showed that under these conditions FUra exhibited a time-dependent removal from DNA accompanied by a decrease in DNA strand length. In the present study we utilized hydroxyurea to inhibit semiconservative DNA synthesis while monitoring DNA repair by measuring the incorporation of [3H]dThd into double-stranded DNA (DNAds), which can be separated from DNA at the replication fork (DNAss) by benzoylated-naphthoylated-DEAE cellulose. Under these conditions we assessed DNA repair in cells that had previously been exposed for 1 h to varying cytotoxic concentrations of FUra. The results demonstrate an increase in labelling of DNAds with increasing FUra concentrations, with no appreciable increase in incorporation of label into DNAss. In conclusion, this study demonstrates that DNA repair occurs following incorporation of FUra. The failure to repair DNA damage at higher FUra concentrations may have a role in the cytotoxicity of this drug.
π SIMILAR VOLUMES
An adaptation of a previously reported flow cytometric technique is described. This technique was applied to study the DNA distribution of mouse granulocyte-macrophage colony forming cells (GM-CFc) grown in a methyl cellulose culture system. This method involved the collection of cell clusters and c
## Abstract The metabolism of 2β²βdeoxyadenosine 5β²βphosphate (dAMP) by exponentially growing mouse fibroblasts (Lβcells) in suspension culture has been studied. Cells incubated for four hours with 0.10 ΞΌmole [^3^H, ^32^P]dAMP/ml in medium containing 9.6 ΞΌmole ^31^P~i~/ml incorporate both activities