Figure 1.

Generation of PS2-deficient (PS2^−/−) mice. (A) Targeting strategy to replace coding exon 5 and flanking sequences of the mouse PS2 gene by a hygromycin cassette. Boxes represent PS2 exons 4, 5, and 6 in the wild-type PS2 gene (upper panel). The lower panel displays the gene locus after targeting. The direction of transcription of the inserted hygromycin cassette is opposite to PS2 transcription (arrow). The predicted lengths of the restriction fragments obtained from the wild-type allele (top) or the targeted allele (bottom) after digestion with EcoRV or combined XbaI and SpeI are shown. (B) Genomic DNA from different ES clones was digested with XbaI and SpeI and was analyzed by Southern blotting using the external 3′probe. (C) Tail genomic DNA from littermate embryos obtained after heterozygote crossings, digested with EcoRV and analyzed by Southern blotting using the external 5′ probe. (D) PCR diagnosis of the PS2 deficient gene in tail genomic DNA.