PHYSICALLY MAPPED, COSMID-DERIVED MICROSATELLITE MARKERS AS ANCHOR LOCI ON BOVINE CHROMOSOMES

To identify physical and genetic anchor loci on bovine chromosomes, 13 cosmids, obtained after the screening of partial bovine cosmid librar ies with the (CA)(n) microsatellite motif, were mapped by fluorescence in situ hybridization (FISH). Eleven cosmid probes yielded a specific signal on one of the bovine chromosomes and identified the following loci: D5S2, D5S3, D6S3, D8S1, D11S5, D13S1, D16S5, D17S2, D19S2, D19S3 , D21S8. Two cosmids produced centromeric signals on many chromosomes. The microsatellite-containing regions were subcloned and sequenced. T he sequence information revealed that the two centromeric cosmids were derived from bovine satellites 1.723 and 1.709, respectively. A cosmi d located in the subtelomeric region of Chromosome (Chr) 17 (D17S2) ha d features of a chromosome-specific satellite. Primers were designed f or eight of the nonsatellite cosmids, and seven of these microsatellit es were polymorphic with between three and eight alleles on a set of o utbred reference families. The polymorphic and chromosomally mapped lo ci can now be used to physically anchor other bovine polymorphic marke rs by linkage analysis. The microsatellite primers were also applied t o DNA samples of a previously characterized panel of somatic hybrid ce ll lines, allowing the assignment of seven microsatellite loci to defi ned syntenic groups. These assignments confirmed earlier mapping resul ts, revealed a probable case of false synteny, and placed two formerly unassigned syntenic groups on specific chromosomes.