Figure 3  Genotyping of weanlings from heterozygote intercrosses. A representative example of the Southern blot genotyping of progeny from a Capn2+/- intercross is shown. Genomic DNA was extracted from mouse tail biopsies taken from three-week old weanlings and genotyped by Southern blotting as described in Figure 1. A 3.5-kb BamHI fragment from the wild-type allele was detected in all animals while a 5.3-kb BamHI fragment from the mutant allele was observed in a subset of progeny. No Capn2-/- offspring were detected among weanlings or post-implantation embryos, nor were embryo resorption sites observed. These results indicate that Capn2-/- embryos perished at a pre-implantation stage.