High speed chromosome measurement and sorting using flow systems

Metaphase chromosomes isolated from Chinese hamster, Indian muntjac and human cells are stained with ethidium bromide and measured for DNA content by flow cytometry at rates of 10⁵/min. The result, a histogram of chromosome frequency versus DNA amount, constitutes a flow karyotype. The chromosomes from a near diploid Chinese hamster cell line (M3-1) with 14 distinct chromosome types yields a histogram with 9 peaks. This is in agreement with scanning cytophotometric measurements of DNA in the same chromosomes. Each of the 5 different chromosomes isolated from male Indian muntjac cells produce a unique peak in the flow karyotype while the 24 human chromosome types are distributed into 7 broad peaks according to their DNA amounts. The time for data collection and reduction is about 10 min per karyotype. In addition, flow sorting permits separation and collection of highly purified populations of single chromosome types for cytological or biochemical analysis. This new flow cytogenetics technology has excellent potential for rapid monitoring of human populations, aberration detection and biochemical analysis of DNA or protein on a per chromosome basis.