Construction and characterization of an ovine bacterial artificial chromosome library

Identification of regions of the genome that contain genes for economically important traits in livestock species and isolation of those genes so that they can be utilized in breeding programs requires high-density genome maps. Large-insert clones such as yeast artificial chromosomes (YAC), P1-deriv...

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Bibliographic Details
Published in:Mammalian genome 1999-11, Vol.10 (11), p.1108-1111
Main Authors: Gill, C A, Davis, S K, Taylor, J F, Cockett, N E, Bottema, C D
Format: Article
Language:English
Subjects:
Animals
Chromosomes, Bacterial - genetics
Cloning, Molecular
Gene Library
Genes, Synthetic - genetics
Genetic Vectors - genetics
Sheep - genetics
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Summary:Identification of regions of the genome that contain genes for economically important traits in livestock species and isolation of those genes so that they can be utilized in breeding programs requires high-density genome maps. Large-insert clones such as yeast artificial chromosomes (YAC), P1-derived artificial chromosomes (PAC), and bacterial artificial chromosomes (BAC) can be used to efficiently obtain accurate, high-resolution physical maps of eukaryotic genomes (Cai et al. 1995). YAC libraries containing clones with inserts up to 1 Mb in size have been constructed for humans (Albertsen et al. 1990), mice (Larin et al. 1993), rats (Cai et al. 1997), cattle (Libert et al. 1993), sheep (Broom and Hill 1994), and pigs (Rogel-Gaillard et al. 1997). However, YAC clones are often chimeric, consisting of DNA from different parts of the genome that have accidentally been combined into a single clone (Libert et al. 1993). This is a serious hindrance to physical mapping and chromosome walking because the true location of the gene of interest cannot be readily determined. BAC libraries have been constructed for a number of plant species as well as for humans (Kim et al. 1996), mice (Research Genetics, Inc., Huntsville, AL), cattle (Cai et al. 1995), chickens (Zimmer and Gibbons 1997), goats (Schibler et al. 1998) and horses (Godard et al. 1998) with cloning systems based on the Escherichia coli F factor. BAC clones are stable, easy to manipulate, and are rarely chimeric (Shizuya et al. 1992; Cai et al. 1995). The only disadvantage of the BAC technology for chromosome walking is that the DNA inserts are somewhat smaller (100-300 kb) than those maintained by YAC clones. Despite this, BAC clones are becoming the vector of choice for physically mapping genes to specific chromosomal locations and for isolating genes by positional cloning. In this paper, we present the construction and characterization of an ovine BAC library containing 59,904 clones with an average insert size of 103 kb, which corresponds to about two genome equivalents. The quality of the library was determined by PCR-based screening and fluorescence in situ hybridization (FISH). A BAC library covering the ovine genome will be a key resource for comparative gene mapping studies, for identifying quantitative trait loci (QTL) by positional cloning, and for functional studies to understand gene expression and regulation.
ISSN:0938-8990
1432-1777
DOI:10.1007/s003359901172