Comparative chromosome map of the laboratory mouse and Chinese hamster defined by reciprocal chromosome painting

Cross-species reciprocal chromosome painting was used to determine homologo us chromosomal regions between the laboratory mouse and Chinese hamster. Wh en mouse chromosome-specific paints were hybridized to Chinese hamster chro mosomes, paints specific for mouse chromosomes 3, 4, 9, 14, 18, 19 and X ea ch painted a single chromosomal region, whilst other mouse paints delineate d multiple discrete chromosomal regions. The mouse Y paint produced non-spe cific signals on Chinese hamster chromosomes. Nineteen mouse autosome paint s identified a total of 47 homologous chromosome regions in the genome of t he Chinese hamster. Hybridization of Chinese hamster paints to mouse chromo somes not only confirmed the above results, but also identified which of th e chromosomal regions of these two species were homologous. In total, 10 Ch inese hamster autosomal paints detected 38 homologous autosomal segments in the mouse genome. A comparative chromosome map was established based on th ese reciprocal chromosome painting patterns. This map forms the basis for e xchanging gene mapping information between the species and for studying gen ome evolution.