Characterization of the 3′ inversion breakpoint inW^sh/W^sh DNA. (A, B) DNA from spleen cells was prepared in agarose plugs, digested with the restriction enzymes PmeI and PmeI+Not1 and resolved by PFGE. The blot was hybridized sequentially with probes 2 and 3 (see Fig 1A), panels A and B, respectively. In +/+ DNA both probes identified same-size fragments. In contrast in W^sh DNA the two probes identified two different fragments. (C) Hybridization of a blot containing W^sh/W^sh and +/+ DNA digested with EcoR1, HindIII, and AccI and hybridized with the 0.9 kb HindIII-AccI probe (see Fig1B) corresponding to sequences at −72 kb identified fragments of distinct sizes in W^sh/W^sh. Size markers are indicated.