ISOLATION AND CHARACTERIZATION OF A PSEUDOAUTOSOMAL REGION-SPECIFIC GENETIC-MARKER IN C57BL 6 MICE USING GENOMIC REPRESENTATIONAL DIFFERENCE ANALYSIS/

Representational difference analysis was used to identify strain-speci fic differences in the pseudoautosomal region (PAR) of mouse X and Y c hromosomes. One second generation (C57BL/6 x Mus spretus) x Mus spretu s interspecific backcross male carrying the C57BL/6 (B6) PAR was used for tester DNA, DNA from five backcross males from the same generation that were M. spretus-type for the PAR was pooled for the driver. A cl oned probe designated B6-38 was recovered that is B6-specific in South ern analysis, Analysis of genomic DNA from several inbred strains of l aboratory mice and diverse Mus species and subspecies identified a cha racteristic Pst I pattern of fragment sizes that is present only in th e C57BL family of strains, Hybridization was observed with sequences i n DBA/2J and to a limited extent with Mus musculus (PWK strain) and Mu s castaneus DNA, No hybridization was observed in DNA of different Mus species, M. spretus, M. hortulanus, and M. caroli. Genetic analyses o f B6-38 was conducted using C57BL congenic males that carry M. spretus alleles for distal X chromosome loci and the PAR and outcrosses of he terozygous congenic females with M. spretus. These analyses demonstrat ed that the B6-38 sequences were inherited with both the X and Y chrom osome. B6-38 sequences were genetically mapped as a locus within the P AR using two interspecific backcrosses, The locus defined by B6-38 is designated DXYRp1. Preliminary analyses of recombination between the d istal X chromosome gene amelogenin (Amg) and the PAR loci for either T elXY or sex chromosome association (Sxa) suggest that the locus DXYRp1 maps to the distal portion of the PAR.