High-resolution RH map of horse chromosome 22 reveals a putative ancestral vertebrate chromosome

• Published in: Genomics (San Diego, Calif.) Calif.), 2005-02, Vol.85 (2), p.188-200
• Main Authors: Gustafson-Seabury, Ashley, Raudsepp, Terje, Goh, Glenda, Kata, Srinivas R., Wagner, Michelle L., Tozaki, Teruaki, Mickelson, James R., Womack, James E., Skow, Loren C., Chowdhary, Bhanu P.
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Biological Evolution; chromosome mapping; Chromosomes; Chromosomes, Artificial, Bacterial; Classical genetics, quantitative genetics, hybrids; Comparative map; ECA22; Equus caballus; FISH; fluorescence in situ hybridization; Fundamental and applied biological sciences. Psychology; Gene mapping; Gene Order; genes; Genes. Genome; genetic markers; Genetics of eukaryotes. Biological and molecular evolution; Horse; horses; Horses - genetics; Human; Humans; In Situ Hybridization, Fluorescence; Methods, theories and miscellaneous; Mice; microsatellite repeats; Molecular and cellular biology; Molecular genetics; Mouse; physical chromosome mapping; Polymerase Chain Reaction - methods; Radiation Hybrid Mapping - methods; radiation hybrid maps; Rats; RH map; Sequence Tagged Sites; Vertebrates - genetics
• ISSN: 0888-7543; 1089-8646
• DOI: 10.1016/j.ygeno.2004.10.012

High-resolution gene maps of individual equine chromosomes are essential to identify genes governing traits of economic importance in the horse. In pursuit of this goal we herein report the generation of a dense map of horse chromosome 22 (ECA22) comprising 83 markers, of which 52 represent specific genes and 31 are microsatellites. The map spans 831 cR over an estimated 64 Mb of physical length of the chromosome, thus providing markers at ∼770 kb or 10 cR intervals. Overall, the resolution of the map is to date the densest in the horse and is the highest for any of the domesticated animal species for which annotated sequence data are not yet available. Comparative analysis showed that ECA22 shares remarkable conservation of gene order along the entire length of dog chromosome 24, something not yet found for an autosome in evolutionarily diverged species. Comparison with human, mouse, and rat homologues shows that ECA22 can be traced as two conserved linkage blocks, each related to individual arms of the human homologue—HSA20. Extending the comparison to the chicken genome showed that one of the ECA22 blocks that corresponds to HSA20q shares synteny conservation with chicken chromosome 20, suggesting the segment to be ancestral in mammals and birds.