[Preparation of monosomal lines containing individual human 15, 21, and X chromosomes]

Sorting of human--mouse or human--hamster hybrid cells with particular human chromosomes was performed by in situ hybridization. Total human genomic DNA was heavily labelled with. H and hybridized to metaphase spreads from hybrid clone cells. The method allowed us to not only identify human chromosomes in hybrid cells but also to detect terminal translocations and insertions from 1-2 bands in length to large ones. Biochemical markers of some human chromosomes were analysed using electrophoretic technique in the clones selected. Cytogenetic analysis (G staining) of these clones was made to visualize human chromosomes. Total 99 initial hybrid human--hamster and 26 human--mouse clones were obtained. 53 clones were analysed by in situ hybridization, only one of them being monochromosomal; the latter contained human X chromosome on the background of Chinese hamster chromosomes. Two other monochromosomal clones containing particular 15 and 21 chromosomes, respectively, were obtained by more complicated way from human--mouse hybrid clones using back selection, repeated hybridization and passing through a number of subsequent subclonings.