The isolation and characterisation of cosmid-derived canine microsatellite DNA sequences

Microsatellites are the most commonly used DNA sequences in genetic mapping studies due to their frequency, distribution and polymorphic properties. (GAAA)n and (CA)n microsatellites were isolated from a partial canine cosmid library using (GAAA)5 and (CA)10 oligonucleotide probes. From a total of 46 cosmids, 25 were subcloned and sequenced, revealing the presence of microsatellite repeats. Oligonucleotide primers flanking the repeat were designed for 17 microsatellites. A total of thirteen cosmid-derived repeats (nine (CA)n and four (GAAA)n) were found to be polymorphic across a panel of DNAs from 12 breeds of dog. Twelve of the cosmids from which the repeats were derived were isolated to eleven separate canine chromosomes by fluorescence in situ hybridisation. Two were assigned to a similar location on canine chromosome 18, and one to the telomeric end of the pseudoautosomal region of the canine sex chromosomes. The rest were assigned to canine chromosomes 2,3,6,7,8,9,20,24 and 30.;Eleven of the thirteen markers were mapped in a set of canine reference families. Eight linkage groups including nine of these markers were revealed, four of which enhanced existing linkage groups, the remainder creating novel linkage groups. Five linkage groups were able to be newly assigned to canine chromosomes. Analysis of DNA sequences surrounding one repeat showed high homology to the 3' UTR of both bovine and ovine IGF II gene sequences, suggesting possible synteny between canine chromosome 18, to which IGF II has been physically mapped, and human, bovine and ovine chromosomes 11, 25 and 21 respectively.;The genetical and physical mapping in this study represent an extension to the size of the canine map as a whole, and to the combination of the genetical and physical maps of the domestic dog.