BIVARIATE FLOW KARYOTYPING, SORTING, AND PEAK ASSIGNMENT OF ALL RAT CHROMOSOMES

A bivariate flow cytometric rat karyotype was established from second- and third-passage Copenhagen (Cop) rat embryo cell cultures. Chromoso me suspensions from such cells (2n = 42 chromosomes) yielded bivariate flow karyotypes composed of 14-18 peaks, 10 of which were sortable in to pools of single chromosome types. Conditions affecting resolution o f peaks (including the length of colcemid treatment of cells and vario us combinations of fluorescent and nonfluorescent dyes) were optimized . Using chromosome suspensions from second-passage cultures of adult C op male and female ear fibroblasts, peaks representing the X and Y chr omosomes were identified. Assignment of chromosomes was accomplished b y polymerase chain reactions of flow-sorted chromosomes using primers from mapped genes. Availability of this characterized rat flow karyoty pe should prove useful for assignment of genes to chromosomes as well as generation of chromosome-specific libraries in cloning assigned gen es. (C) 1994 Academic Press, Inc.