Fig. 2. Identification of a candidate svs mutation. (A) Representative Southern blot of genomic DNA from svs, C57BL/6By (B6), and Balb/cBy (Balb) mice digested with BamHI and probed with a fragment from Fgfr2. Note the shift of a major band only in svs mutant mice (arrowhead). (B) PCR of svs, C57BL/6By (B6), and Balb/cBy (Balb) mouse genomic DNA using primers flanking the candidate mutation. The parental control strains Balb/cBy and C57BL/6By have a 399 bp band, whereas svs mutant mice have an 890 bp band. (C) Genomic structure of Fgfr2. The horizontal arrow indicates the direction of transcription; the vertical lines indicate exons; and the vertical arrow indicates the intron which harbors the svs insertion (top). Sequencing of PCR products from svs mutant mice revealed a 491 bp insertion flanked by intronic Fgfr2 sequences (bottom). Abbreviations: mChr7, mouse chromosome 7.