[Show abstract][Hide abstract] ABSTRACT: Ovis aries chromosome one (OAR1) is the largest submetacentric chromosome in the sheep genome and is homologous to regions on human chromosomes 1, 2, 3 and 21. Using the USUoRH5000 ovine whole-genome radiation hybrid (RH) panel, we have constructed a RH map of OAR1 comprising 102 framework and 75 placed/binned markers across five linkage groups spanning 3759.43 cR5000, with an average marker density of 21.2 cR5000/marker. The alignment of our OAR1 RH map shows good concordance with the recently developed virtual sheep genome, with fewer than 1.86% discrepancies. A comparative map of OAR1 was constructed by examining the location of RH-mapped orthologues in sheep within the genomes of cow, human, horse and dog. Analysis of the comparative map indicates that conserved syntenies within the five ovine RH linkage groups underwent internal chromosomal rearrangements which, in general, reflect the evolutionary distances between sheep and each of these four species. The ovine RH map presented here integrates all available mapping data and includes new genomic information for ovine chromosome 1.
[Show abstract][Hide abstract] ABSTRACT: A comprehensive physical map was generated for Ovis aries chromosome X (OARX) based on a cytogenomics approach. DNA probes were prepared from bacterial artificial chromosome (BAC)
clones from the CHORI-243 sheep library and were assigned to G-banded metaphase spreads via fluorescence in-situ hybridization
(FISH). A total of 22 BACs gave a single hybridization signal to the X chromosome and were assigned out of 32 tested. The
positioned BACs contained 16 genes and a microsatellite marker which represent new cytogenetically mapped loci in the sheep
genome. The gene and microsatellite loci serve to anchor between the existing radiation hybrid (RH) and virtual sheep genome
(VSG) maps to the cytogenetic OARX map, whilst the BACs themselves also serve as anchors between the VSG and the cytogenetic
maps. An additional 17 links between the RH and cytogenetic maps are provided by BAC end sequence (BES) derived markers that
have also been positioned on the RH map. Comparison of the map orders for the cytogenetic, RH, and virtual maps reveals that
the orders for the cytogenetic and RH maps are most similar, with only one locus, represented by BAC CH243-330E18, mapping
to relatively different positions. Several discrepancies, including an inverted segment are found when comparing both the
cytogenetic and RH maps with the virtual map. These discrepancies highlight the value of using physical mapping methods to
inform the process of future in silico map construction. A detailed comparative analysis of sheep, human, and cattle mapping data allowed the construction of a
comparative map that confirms and expands the knowledge about evolutionary conservation and break points between the X chromosomes
of the three mammalian species.
Full-text · Article · May 2009 · Chromosome Research
[Show abstract][Hide abstract] ABSTRACT: A radiation hybrid (RH) map of sheep X chromosome (Ovisaries; OARX) containing 146 physically anchored loci was generated in this study, providing information for comparative X chromosome analysis between the maps of sheep, human, 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 genome 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 contributes 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.
Full-text · Article · Feb 2009 · Cytogenetic and Genome Research
[Show abstract][Hide abstract] ABSTRACT: In this study, we constructed high-resolution radiation hybrid (RH) and comparative maps of ovine chromosomes or chromosomal segments that are homologous to human chromosome 6 (HSA6). A total of 251 markers were successfully genotyped across the recently developed USUoRH5000 whole-genome panel; 208 of these markers were assigned to five RH linkage groups distributed on three ovine chromosomes (OAR8, 9 and 20). The RH maps have good correspondence with previous chromosome painting data, although a small centromeric region on OAR9 that is homologous to HSA6 had not been previously detected using human chromosome paints on ovine chromosomal spreads. High percentages of the ovine markers were identified as orthologues in the bovine (86.3%), dog (85.8%), horse (69.3%) and human (88.7%) genomes. These maps contribute to investigations in mammalian chromosome evolution and the search for economic trait loci in sheep.