Figure 5.

Sequencing of the boundaries of the repeat unit. (a) Sequence of the proximal boundary of the repeat unit showing the normal sequence (upper line) and the inverse PCR product (lower line), representing the inner junctions formed in Wld^s. The two sequences can be aligned exactly, except for 19 bp (angled) that are unique to the inverse PCR product. These 19 bp are derived from the distal end of the repeat unit, having been juxtaposed in C57BL/Wld^s by the formation of the junction (Fig. 2d). PstI sites shown left and right are the sites of circularization during inverse PCR. The 8-bp sequence shared between the proximal and distal boundaries is boxed. Sequences of PCR primers, represented by horizontal arrows, are 54 = 5′-CGTTGGCTCTAAGGACAGCAC-3′ and 59 = 5′-CGCCTCTTTGATCCCTACAGA-3′. (b) Sequence of the distal boundary of the repeat unit showing the approximate site of the boundary and the 8-bp motif common to the distal and proximal boundaries (boxed). The inverse PCR product diverges at a slightly different point from the normal distal and proximal sequences. This, and the possibility that one or two bases may be coincidentally shared between sequences, makes it difficult to define the exact site of each boundary.