COMPARATIVE GENE-MAPPING - A FINE-SCALE SURVEY OF CHROMOSOME REARRANGEMENTS BETWEEN RUMINANTS AND HUMANS

A total of 202 genes were cytogenetically mapped to goat chromosomes, multiplying by five the total number of regional gene localizations in domestic ruminants (255). This map encompasses 249 and 173 common anc hor loci regularly spaced along human and murine chromosomes, respecti vely, which makes it possible to perform a genome-wide comparison betw een three mammalian orders. Twice as many rearrangements as revealed b y ZOO-FISH were observed. The average size of conserved fragments coul d be estimated at 27 and 8 cm with humans and mice, respectively. The position of evolutionary breakpoints often correspond with human chrom osome sites known to be vulnerable to rearrangement in neoplasia. Furt hermore, 75 microsatellite markers, 30 of which were isolated from gen e-containing bacterial artificial chromosomes (BACs), were added to th e previous goat genetic map, achieving 88% genome coverage. Finally, 1 24 microsatellites were cytogenetically mapped, which made it possible to physically anchor and orient all the linkage groups. We believe th at this comprehensive map will speed up positional cloning projects in domestic ruminants and clarify some aspects of mammalian chromosomal evolution.