Differential giemsa staining of sister chromatids after extraction with acids

Abstract

Chromosomes of Chinese hamster strain cells were air-dried on slides after BrdU substitution for two or three rounds of replication. The preparations were treated with 20% PCA at 55° C for 20–30 min, or 5N HCl at 55° C for 15–20 min. After staining with Giemsa, unifilarly BrdU-substituted chromatids stained faintly and bifilarly substituted chromatids stained darkly. Such a pattern of sister chromatid differential staining was confirmed by the examination of metaphase cells grown with BrdU for three rounds of replication.