Study on the related factors for the differential staining results of sister chromatid

Objective To explore the effects of frozen storage time of bromodeoxyuridine(BrdU) solution,storage time of chromosome slides,ultraviolet exposure time and temperature on the differential staining results of sister chromatid,and to figure out whether it is feasible to put the technique as a classroom experiment project.Methods The chromosome slides were prepared by the standard methods of peripheral blood lymphocyte culture and chromosome preparation.The cells were cultured with the BrdU solutions prepared freshly and stored for 10 years at-20 ℃,respectively.The chromosome slides prepared freshly and stored at-20 ℃ for 1,2,3,4,5 weeks were taken for the ultraviolet irradiation at 50,56 and 60 ℃ for 10,20 and 30 min,respectively,and then stained with Giemsa for 10 min at the room temperature.The effects of the factors on the differential staining were evaluated according to the staining results and colour difference of the chromatids.Results The staining results of chromatids showed no significant difference after incorporating into DNA with BrdU prepared freshly and stored at-20 ℃ for 10 years,and the most appropriate final concentration of BrdU was 10 μg/ml.Good differential staining results were obtained from the chromosome slides prepared freshly and stored at-20 ℃ for 1-5 weeks by UV radiation for 10-30 min.Conclusion BrdU solution can be stored at-20 ℃ for a long-term without affecting the chemical incorporation into DNA.Chromosome slides stored at-20 ℃ can be used for sister chromatid differential staining in 5 weeks after preparation.Sister chromatid differential staining is a technique which is tolerant toward the changes of the related factors,and it is entirely feasible as a classroom experiment after the factors are improved.