We have identified 149 hybridization probes at 10-cM intervals in the mouse and have confirmed their order and linkage by fluorescence in situ hybridization. These probes represent a new resource for mapping in the mouse and can be used to correlate linkage and cytogenetic maps, to map novel sequences to within a few centimorgans, to relate cytogenetic abnormalities to the genetic map, and to make cross-species comparisons.

We have developed a method, which we have named hybridization-banding, to identify simultaneously all chromosomes in a mouse metaphase spread. The method uses a combination of hybridization probes labeled with a single fluor to yield a simple, unique, readily identifiable hybridization pattern on each chromosome. The method is superior to Giemsa- or fluorescence-based banding methods for chromosome identification because the hybridization patterns are simpler and easier to identify, and unique patterns can be designed at will for each chromosome. Analysis can be performed with a standard fluorescence microscope, and images can be recorded on film with an ordinary 35-mm camera, making the method useful to many investigators. The method can also be applied to any species for which chromosomes and probes can be prepared.

Bovine chromosome 20 (BTA20) is associated with several quantitative trait loci (QTL) for meat tenderness, birth weight, milk yield and composition. Fine mapping of these QTL requires the development of additional informative markers to increase the resolution of the BTA20 genetic and physical maps. A BTA20-specific library was constructed by means of microdissection and microcloning, and screened for dinucleotide repeats with (CA)16 and (GT)16 oligos. A total of 60 new microsatellites (MS) were developed and characterized for polymorphism using the U.S. Department of Agriculture (USDA)/Meat Animal Research Center (MARC) bovine reference family, of which 53 markers were informative in this family. The number of alleles for these loci varied from 1 to 14, with an average of 6.5. Thirty-three of these MSs, together with 105 markers previously mapped to BTA20, were scored on a 7000-rad cattle-hamster whole-genome radiation hybrid panel (SUNbRH), resulting in a high-resolution RH7000 rad map for BTA20.

No abstract

No abstract