Figure 2

The frequency of polymorphisms varies along the chromosome arm. Black bars indicate the number of 200-300 bp DNA fragments tested that are polymorphic between the FRT 82B and the marker chromosome as detected by SSCP; gray bars show the total number of DNA fragments tested. Black squares show the percentage of DNA fragments tested that are polymorphic out of the total number of fragments tested. The x-axis is co-linear with the molecular map of the chromosome, with each region representing about 1.5 Mb (six genomic scaffold sections). For convenience, the correspondence to the cytological map is indicated below. A linear regression of the percentage of polymorphisms (data not shown) confirms that the frequency of polymorphisms decreases towards the centromere. Cytological region 94 shows a strong unexplained dip in the frequency of polymorphisms.