title: Analysis of the length of S-phase required to show sister chromatid differential staining.
abstract: In vitro studies of BrdU-dependent sister chromatid differential staining typically employ two cycles of BrdU incorporation. Experiments are described which determined the actual fraction of both S-phases that the rat embryonic fibroblasts (Rat-1) cells had to traverse in order to show distinctive differential staining. Following synchronization of cells by a combination of serum deprivation and hydroxyurea blockage, sister chromatid differential staining, labelling index, mitotic index, and per cent DNA replication are determined. Results indicate that only approximately 50% of the first S-phase is necessary in order to show distinctive differential staining. The importance of this finding to studies of cellular proliferation using BrdU incorporation is discussed.
mesh_terms: D000818:Animals; D001973:Bromodeoxyuridine; D002453:Cell Cycle; D002460:Cell Line; D002842:Chromatids / Q000378:metabolism*; D004261:DNA Replication; D007399:Interphase; D008677:Metaphase; D008940:Mitotic Index; D051381:Rats; D013194:Staining and Labeling; D013936:Thymidine / Q000378:metabolism
chemical_list: D001973:Bromodeoxyuridine; D013936:Thymidine