Characterization, genetic and physical mapping analysis of 36 horse plasmid and cosmid-derived microsatellites.

Thirty-six new horse microsatellites (11 from plasmid libraries and 25 from a cosmid library) were isolated and characterized on a panel of four horse breeds. Thirty were found to be polymorphic with heterozygosity levels ranging between 0.20 and 0.87. Twenty-two of the cosmids were physically mapped to R-banded single horse Chromosomes (Chrs) 1, 3, 4, 9, 11, 12, 13, 15, 18, 19, 21, 22, 23 and three to pericentromeric regions. Furthermore, linkage analysis between a selection of 42 DNA markers, including those presented in this study, and 16 conventional markers of the horse hemotype was performed on six paternal half-sib horse families. Five linkage groups were detected, of which four were assigned to Chr 10, 11, 15, and 18. This work increased by one-third the number of published polymorphic DNA markers suitable for horse mapping and approximately doubled the number of known linkage groups. Our cosmids labeled 14 out of the 31 horse autosomes. Moreover, the physical anchoring of part of these markers will orient linkage and synteny groups on the chromosomes and will contribute to their assignment.