Figure 3.

Southern analysis of the region surrounding the pseudoautosomal boundary. Male and female DNAs from mice of the FVB and C57BL/6 strains and from a female C57BL/10 mouse digested with BamHI and EcoRV were analyzed by Southern blotting and probed with DNA fragments derived from either side of the pseudoautosomal boundary and from an autosomal gene as a loading control. (Middle) A blot probed with DXCbl1 shows that this STS is X-unique and gives a 2:1 ratio of hybridization intensity in female and male lanes. (Top) The same blot stripped and reprobed with DXYCbl1 showing hybridization to the same X-linked band as DXCbl1 in the BamHI cut lanes and an additional, more intense, band at 6.5 kb derived from the pseudoautosomal repeats in the C57BL/10 and C57BL/6 lanes. The repeat band appears to be absent in the FVB female and of an altered allele size in the FVB male. The single 12-kb repeat band in the C57BL/10 female demonstrates that the repeat unit must be at least this size and is probably larger because there are no junction fragments. (Bottom) The same blot stripped and reprobed with a fragment of the autosomal gene Tcp-1 (31) to show equivalence of loading between male and female tracks.