CHROMOSOMAL LOCALIZATION AND MOLECULAR CHARACTERIZATION OF 53 COSMID-DERIVED BOVINE MICROSATELLITES

Gene mapping in cattle has progressed rapidly in recent years largely owing to the introduction of powerful genetic markers, such as the mic rosatellites, and through advances in physical mapping techniques such as synteny mapping and fluorescence in situ hybridization (FISH). Mic rosatellite markers are often not physically mapped because they are g enerally isolated from small insert plasmid libraries, which makes the ir chromosomal localization inefficient. In this report we describe th e FISH mapping of a large group of cosmid-derived bovine microsatellit e markers, as our contribution to the European mapping initiative, Bov Map. One objective of BovMap is to develop a set of anchored loci for the cattle gnome map. Two cosmid libraries were screened with probes c orresponding to the (AC)(n) microsatellite motif. Positive clones were mapped by FISH, and then a subset was further analyzed by sequencing the region flanking the microsatellite repeat. In total, 58 clones wer e hybridized with chromosomes and identified loci on 22 of the 31 diff erent bovine chromosomes. Three clones contained satellite DNA. Two or more markers were placed on 12 chromosomes. Sequencing of the microsa tellites and flanking regions was per formed directly from 43 cosmids, as previously reported (Ferretti et al. Anim. Genet. 25, 209-214, 199 4). Primers were developed for 39 markers and used to describe the pol ymorphism associated with the corresponding loci.