High-resolution physically ordered gene maps for the horse (Equus caballus,
ECA) are essential to the identification of genes associated with hereditary diseases and
traits of interest like fertility, coat color, and disease resistance or susceptibility. Such
maps also serve as foundations for genome comparisons across species and form the
basis to study chromosome evolution. In this study seven equine chromosomes (ECA6,
7, 10, 15, 18, 21 and X) corresponding to human chromosomes (HSA) 2, 19 and X were
selected for high-resolution mapping on the basis of their potential involvement in
diseases and conditions of importance to horses. To accomplish this, gene- and
sequence-specific markers were generated and genotyped on the TAMU 5000rad horse x
hamster RH panel. Additionally, screening of a BAC library by overgoes and
subsequent STS content mapping and fingerprinting approaches were used to assemble
and verify a BAC contig along a ~5 Mb span on ECA21.
Dense gene maps were generated for each of the seven equine chromosomes by
adding 408 new markers (285 type I and 123 type II) to the current maps of these
chromosomes, thereby greatly improving overall map resolution to one mapped marker
every 960kb on average (range: 700 kb â 1.3 Mb). Moreover, the contig on ECA21 contained 47 markers (42 genes and 5 microsatellites) as well as 106 STS markers
distributed along 207 BAC clones. Comparisons of these maps with other species
revealed a remarkably high level of horse-human X chromosome conservation, as well
as two evolutionary breakpoints unique to Perissodactyls or Equids for the equine
homologues of HSA19 and HSA2, one of which has been more precisely localized by
the ECA21 contig. Thus, high resolution maps developed for these chromosomes i)
provide a basis to map traits of interest rapidly to specific chromosomal regions, ii)
facilitate searches for candidate genes for these traits by fine comparisons of the equine
regions with corresponding segments in other species, and iii) enable understanding the
evolution of the chromosomes. Expansion of this work to the entire equine genome will
be important for developing novel strategies for diagnosis, prevention, and treatment of
equine diseases.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/4687 |
| Date | 25 April 2007 |
| Creators | Brinkmeyer Langford, Candice Lea |
| Contributors | Chowdhary, Bhanu P. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | 4501679 bytes, electronic, application/pdf, born digital |
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