Fig. 2. Targeting a null mutation to the murine Sox17 gene. (A-C) The Sox17 targeting strategy. Restriction sites: B, BamHI; E, EcoRI; C, ClaI. The green bold bar indicates the position of the probe for genomic Southern blot hybridisation using the BamHI-digested samples (mutated allele, 9.0 kb; wild-type allele, 5.0 kb) (genotyping results of ES cells and adult mice are shown in B), while the red arrowheads show the primer positions for genome typing by PCR (results of 8.5 dpc embryos are shown in C). (D) Lack of Sox17 synthesis in mutant 7.5 dpc mouse embryos revealed by immunoblot analysis using anti-Sox17 C17-antibody (Kanai et al., 1996).