THE APPLICATION OF FISH TECHNIQUES FOR PHYSICAL MAPPING IN THE DOG (CANIS-FAMILIARIS)

The abundance of CA/GT repeats in the DNA of the dog (Canis familiaris ) has established the importance of polymorphic microsatellites in the development of a low density map of the canine genome. The assignment of linkage groups of markers to chromosomes by physical mapping requi res reliable cytogenetic techniques for routine production of metaphas e cells. The dog has 78 chromosomes, many of which are smaller and mor e contracted than those of other mammals. Although the molecular study of inherited disease in dogs has important implications for both impr oved welfare in dogs and the provision of animal models for human dise ases, the small size and large number of chromosomes in the canine gen ome has discouraged the inclusion of cytogenetic analysis in the plann ing of relevant research protocols. In this report, Fluorescence In Si tu Hybridization (FISH) techniques have been optimized for the physica l mapping of probes in C. familiaris. A method to obtain a good yield of early and midmetaphases from shea-term peripheral blood cultures an d the optimal conditions for hybridization and detection of probes is described. Thirteen microsatellite-containing cosmid probes from a can ine genomic library in pWE15, a highly repetitive probe (human ribosom al DNA pHr14E3), and a human X Chromosome (Chr) paint have been mapped . Six microsatellites, two ribosomal sites, and the human paint have b een assigned to specific chromosomes.