Community Research and Development Information Service - CORDIS

Genomic tools for fine mapping bovine chromosome 9

We have mapped a large number of microsatellite and EST/gene markers onto the RH map for BTA9. A total of 161 markers have successfully been mapped onto BTA9. Of these, 61 were from a previous study undertaken within the same laboratory (Williams et al 2002) resulting in approximately 100 new markers added to the RH map since the publication. The first step to building RH maps is to cluster the markers into linkage groups on chromosomes. Markers for the RH map of BTA9 fall into a single LOD4 and LOD 6 linkage groups spanning the whole chromosome of BTA9. The linkage groups were identified using Carthagene and were robust for LOD4 and LOD6 (data not shown).

This maps allows for fine positioning of important markers. Generally linkage maps allow good positioning of markers over a large area within the chromosome, however, RH maps allow for reliable marker placement over shorter distances, particularly important for fine mapping of QTLs.

A high-density linkage map for BTA9 has been created by integrating new information from the MASTITIS RESISTANCE project RH map, bovine genome sequence and project linkage data. Some genotyped markers were discarded from the final linkage maps because either there was not enough linkage information to determine their linkage position unambiguously and they have not been mapped by any other method or because they gave high number of recombination events at any of the proposed positions (which may indicate undetected genotyping errors or null alleles). The most reliable map consists of 59 markers with the total map length being 97.7cM.

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Genomics and Bioinformatics
United Kingdom
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