The isolation and characterisation of canine minisatellite DNA sequences.

A Charomid ordered array library containing the 2-16kb size fraction of MboI-digested canine genomic DNA was screened with the multilocus probes, 33.6 and 33.15. Testing for polymorphism of the minisatellite loci in 48 resulting positive clones yielded seven polymorphic minisatellites with heterozygosities in the range 20-88%. Mendelian inheritance was confirmed shown for two of the polymorphic minisatellites. DNA fingerprinting studies of the level of inter- and intra-breed variation did not show any significant difference between the two. Analysis of intra-breed variation in Bedlington Terriers using two polymorphic minisatellites as single-locus probes revealed a significant reduction in the number of alleles in comparison with an agglomerated population sample, consistent with the high level of inbreeding within this breed. Multi-locus canine minisatellite probe analysis of unrelated species showed that related repeat sequences are present in numerous species. Use of single-locus canine minisatellite probes to analyse related canids suggested that polymorphic canine minisatellites are likely to show transience in their variability and detection, whereas monomorphic minisatellites are stable and more readily detected in related canids. Use of cCfaMP5, the most polymorphic canine minisatellite isolated to date, as a single-locus probe in paternity analysis demonstrates its applicability to forensic problems. Flanking sequence and partial repeat sequence data obtained for the minisatellite in cCfaMP5. The variable region in this minisatellite region is similar to many human minisatellites which show a distinct purine or pyrimidine strand bias. A mechanism whereby this minisatellite might have evolved is suggestedon the basis of the distribution and kinds of repeat units. An initial MVR-PCR analysis of CfaMP5 has been carried out and, with future optimization, it should be possible to digitally type canine minisatellite alleles, thereby widening the scope of the analysis of canine minisatellite variation.