Flow cytometric characterization of a Chinese hamster X man hybrid cell line retaining the human Y chromosome.

A Chinese hamster X man hybrid cell line (CH-Y-VII) was established which retains a free human Y chromosome. Exponentially growing CH-Y-VII cells were arrested with colcemid; metaphase chromosomes were isolated and stained with 33258 Hoechst (HO) plus Chromomycin A3 (CA3), or with ethidium bromide (EB). The HO/CA3-stained chromosomes were measured in a dual beam flow cytometer, and bivariate HO/CA3 flow karyotypes and univariate HO and CA3 flow karyotypes were established. EB-stained chromosomes were analyzed in a modified Becton Dickinson FACS-Sorter. For all three stains used, the human Y chromosome forms a separate peak in univariate flow karyotypes; the optimum resolution was obtained for the HO distribution. In the bivariate HO/CA3 flow karyotype, the peak for the human Y chromosome is completely separated from the Chinese hamster chromosomes.