Slit-scanning technique using standard cell sorter instruments for analyzing and sorting nonacrocentric human...

We have investigated the performance of two types of standard flow cell sorter instruments, a System 50 Cytofluorograph and a FACSTar PLUS cell sorter, for the on-line centromeric index (CI) analysis of human chromosomes. To optimize the results, we improved the detection efficiency for centromeres in two ways. A higher efficiency was obtained first by elongation of the chromosomes and second by introducing a high resolution lens system for laser beam focusing. In the two-parameter flow karyotype of CI and DNA content of human chromosomes, distinct peaks are produced not only by the larger chromosomes 1-8 and X, but by the smaller nonacrocentric chromosomes 9-12 and 16-20 as well. As the chromosomes 9-12 cannot be distinguished by other flow karyotyping methods, we discriminated and sorted chromosomes 12 and 10 from 9 and 11 to investigate the capacity for the separation of chromosomes in this group. A purity of at least 90% was achieved; in the isolated population the fraction chromosomes 12 was 55%; the remaining 45% were chromosomes 10 (40%) and unidentifiable chromosomes (5%).