Figure 5.

Southern blot analysis identifies breakpoint in SNRPN intron 17 . a . Restriction map of the intron 17 region of the SNRPN gene on the normal chromosome 15. Black arrowheads indicate the boundaries of intron 17. The positions of the two hybridization probes (SB-1 and SB-3) are indicated by green lines. b . Lanes 1 and 2 contain double digests with NheI and BsaWI to release a fragment of 6.4 kb, lanes 3 and 4 contain double digests with NheI and ApaI to release a fragment of 10 kb. The membrane was probed with probe SB-1. The arrow indicates an additional band above the 10 kb fragment ~11.5 kb in length. The two bands are not well resolved on the rendition of this blot. This novel fragment is represented in c, upper panel. Lanes 5 and 6 contain double digests with NheI and ApaI to release a 10 kb fragment. The membrane is probed with SB-3. The arrow indicates an additional band of ~ 7 kb. This novel fragment is represented schematically in c, lower panel. c . Schematic representation of the junction fragments identified on the Southern blot in b. The upper panel represents the der(15) and the lower panel represents the der(4). Chromosome 15 material is indicated as a black line and material from chromosome 4 as a blue line. Location of restriction sites and of hybridization probes (green lines) are indicated.