SLIT-SCANNING TECHNIQUE USING STANDARD CELL SORTER INSTRUMENTS FOR ANALYZING AND SORTING NONACROCENTRIC HUMAN-CHROMOSOMES, INCLUDING SMALL ONES

We have investigated the performance of two types of standard flow cel l sorter instruments, a System 50 Cytofluorograph and a FACSTar PLUS c ell sorter, for the on-line centromeric index (CI) analysis of human c hromosomes. To optimize the results, we improved the detection efficie ncy for centromeres in two ways. A higher efficiency was obtained firs t by elongation of the chromosomes and second by introducing a high re solution lens system for laser beam focusing. In the two-parameter flo w 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 chr omosomes 9-12 cannot be distinguished by other flow karyotyping method s, we discriminated and sorted chromosomes 12 and 10 from 9 and 11 to investigate the capacity for the separation of chromosomes in this gro up. A purity of at least 90% was achieved; in the isolated population the fraction chromosomes 12 was 55%; the remaining 45% were chromosome s 10 (40%) and unidentifiable chromosomes (5%). (C) 1994 Wiley-Liss, I nc.