BOREALIS aims to develop the resources and methodology required for genetic and physical fine-mapping of Economic Trait Loci (ETL) in cattle, a fundamental prerequisite to allow their efficient use in Marker Assisted Selection programs. The proposal is divided in four interrelated Work Packages. Work Page 1 comprises the construction of bovine large-fragment DNA libraries in YAC and PAC vectors. Both libraries will be characterised for average insert size, genome coverage and degree of chimerism. Both libraries will be stored, handled and distributed via the Reference Library Database. Each library will be freely available on request, to the scientific community. Work package 2 comprises the development of "Comparative Mapping of Anonymous Exons". The objective is to determine the homologous locus on the human gene map of an ETL of interest in cattle. The strategy is based on the predicted cross-hybridization between anonymous exons contained in bovine large insert clones isolated with microsatellite markers shown to be linked to the trait of interest. Three alternative approaches will be evaluated in a trial experiment involving wellcharacterised loci: CFTR and MHC. The most efficient method will then be applied to three specific ETL: MH, Polled and a QTL for milk production. The identification of the human homologous locus will allow the use of neighbouring human ESTs as a source of candidate genes and as conserved STSs for contig construction in cattle.
Work Package 3 consists in the generation of additional STSs specific for the three ETL of interest by chromosome-band microdissection and amplification. The chromosome-band carrying the ETL of interest will be identified by FISH using bovine large insert clones isolated with microsatellite markers linked to the trait of interest.
In Work Package 4, both types of STSs will be used jointly to screen the bovine large insert libraries and build contigs for the three ETL of interest by STS content mapping. FISH to extended chromatin fibres will be used as a complementary methodology towards contig construction.
Microsatellite markers will be isolated from these contigs and used for genetic fine-mapping of the three targeted ETLs.
Funding SchemeCSC - Cost-sharing contracts
EH25 9PS Roslin