TECHNIQUE FOR SIMULTANEOUS DEMONSTRATION OF G-BANDS AND SISTER CHROMATID EXCHANGES

Sister chromatid differential staining occurs when cells are grown in medium containing 5-bromodeoxyuridine (BrdU) for two cell cycles and are then treated with special fluorochromes and/or Giemsa. These methods thus allow the detection of sister chromatid exchanges (SCEs). However, the exact localization of SCE points is only possible by means of time-consuming sequential staining-destaining-restaining procedures or by combined BrdU-trypsin-Giemsa or BrdU-acridine-orange treatment, which reveal bands on one chromatid only. Morgan and Crossen (1977) report on a few metaphases randomly found among cells treated by the Korenberg technique which showed both G bands and differential staining of sister chromatids. The combined BrdU-Giemsa banding technique presented here allows the localization of SCE points with more accuracy and less employment.