Construction of a 5000rad whole-genome radiation hybrid panel in the horse and generation of a comprehensive and comparative map for ECA11

A 5000(rad) whole-genome radiation hybrid (RH) panel was created for the horse. The usefulness of the panel for generating physically ordered maps of individual equine chromosomes was tested by typing 24 markers on horse Chromosome 11 (ECA11). The overall retention of markers on this chromosome was 43.6%. Almost complete retention of two of the typed markers-CA062 and AHT44-clearly indicated the location of thymidine kinase gene on the short arm of ECA11. Seven of the typed markers were FISH mapped to align the RH and cytogenetic maps. With the RH-MAPPER approach, a physically ordered map comprising four linkage groups and incorporating all the markers was obtained. The study provides the first comprehensive map for a horse chromosome that integrates all available mapping data and adds new information that spans the entire length of the equine chromosome. The map clearly underlines the resolving power and utility of the panel and emphasizes the need to have uniformly distributed cytogenetic markers for appropriate alignment of RH map with the chromosome. A comparative status of the ECA11 map in relation to the corresponding human/mouse chromosome is presented.