[Optimization of the conditions for the in situ hybridization of cloned DNA sequences and for the differential staining of human chromosomes].

The influence of different experimental conditions on in situ hybridization of DNA and subsequent differential staining of chromosomes was studied. The most optimal conditions for chromosomal localization of cloned repetitive DNA sequences were the lack of chromosome pretreatment with acid and RNase, reduction of the denaturation time to 30 s, carrying out of hybridization at a relatively low temperature (under 37 degrees C) at the expense of the use of formamide, addition to the hybridization mixture of 10% of dextran sulfate-500. The conditions indicated permit obtaining on radioautographs the G- and C-segmentation of human chromosomes.