Fax +41 61 306 12 34 E-Mail karger@karger.ch www.karger.com Original Article Cytogenet Genome Res 2009;125:40–45 DOI: 10.1159/000207520 A High-Resolution Radiation Hybrid Map of Sheep Chromosome X and Comparison with Human and Cattle T. Goldammer a R.M. Brunner a A. Rebl a C.H. Wu b K. Nomura e T. Hadfield b C. Gill c B.P. Dalrymple f J.E. Womack d N.E. Cockett b a Forschungsbereich Molekularbiologie, Forschungsinstitut für die Biologie landwirtschaftlicher Nutztiere (FBN), Dummerstorf, Germany, b Department of Animal, Dairy, and Veterinary Sciences, Utah State University, Logan, UT, Departments of c Animal Science and d Veterinary Pathobiology, Texas A&M University, College Station, TX, USA; e Tokyo University of Agriculture, Department of Animal Science, Laboratory of Animal Genetics and Breeding, Kanagawa, Japan; f CSIRO Livestock Industries, Queensland Bioscience Precinct, St Lucia, QLD, Australia The physical gene map of sheep is not as developed as gene maps of other domestic animals such as cattle, horse, pig, honey bee, or chicken, although interest in sheep pro- duction around the globe is steadily growing and there are more than 1.3 billion sheep in the world [FAO, 2007]. Publicly available DNA sequence data of other Bovidae, like cattle, have been used for genome analysis in sheep and other small ruminants. However, small differences between species in genome morphology and organiza- tion provide evidence of evolutionary differences among species [Yunis and Prakash, 1982; Fortna et al., 2004; Watanabe et al., 2004]. Comparative genome analysis be- tween distantly related species, such as human, mouse, and sheep, provides information about conserved synte- ny between genomes and evolutionary relationships. On the other hand, comparative mapping between closely re- lated species, such as sheep, cattle, river buffalo, and goat, contributes information on evolutionary species origin, genome and chromosome conservation, and compara- tive data for genome regions and genes that influence traits. In this study, we conducted an extensive analysis of the X chromosome in sheep since X chromosome morphol- ogy and banding structure differ between sheep and cat- tle. In contrast, there is strong similarity between most of Key Words BTAX  Comparative map  HSAX  OARX  Ovine chromo- some X  Radiation hybrid map  Sheep Abstract A radiation hybrid (RH) map of sheep X chromosome (Ovis aries; OARX) containing 146 physically anchored loci was generated in this study, providing information for compara- tive X chromosome analysis between the maps of sheep, hu- man, and cattle. Primers typed on the USUoRH5000 ovine whole-genome radiation hybrid panel were designed from sequences predicted to be on the ovine X chromosome, based on comparative mapping within the virtual sheep ge- nome browser (v1.2). The resulting RH map for the ovine X chromosome consists of 4 linkage groups composed of 76 BAC end sequences (BES), 28 gene loci that were confirmed within ovine BAC clones in the CHORI-243 ovine BAC library, 28 additional gene loci from the ovine comparative map and 14 polymorphic sequence tagged sites (STS) from the OARX linkage map. This first-generation RH map of OARX contrib- utes to the expansion of a comprehensive ovine genome map for sheep and provides evidence of rearrangements in loci order compared to the human and cattle orders. Copyright © 2009 S. Karger AG, Basel Accepted after revision: January 7, 2009 by J. Smith Tom Goldammer, Forschungsbereich Molekularbiologie Forschungsinstitut für die Biologie landwirtschaftlicher Nutztiere (FBN) Wilhelm-Stahl-Allee 2, D–18196 Dummerstorf (Germany) Tel. +49 (0)38208 68708, Fax: +49 (0)38208 68702 E-Mail tomgoldammer@fbn-dummerstorf.de © 2009 S. Karger AG, Basel 1424–8581/09/1251–0040$26.00/0 Accessible online at: www.karger.com/cgr