Fig. 1. Targeted disruption of the Aldh1a1 gene encoding RALDH1. (A) Structure of the targeting vector and partial restriction map of the Aldh1a1 locus before [wild-type (WT) allele, +] and after homologous recombination (L3 allele) and Cre-mediated recombination (L2 and L-alleles). Black boxes (labeled 7-9) stand for exons. The location of restriction sites (B, BamHI; H, HpaI; S, SalI) and of the 3' external probe is indicated. Arrowhead flags represent loxP sites. Arrows indicate the location of primers 1 and 2 used for PCR genotyping. Sizes of the restriction fragments obtained for each allele are shown below and are in kilobases (kb). (B) Southern blot analysis of HpaI-digested genomic DNA from ES cell clones with the indicated Aldh1a1 genotype, using the 3' probe. (C) PCR analysis of tail genomic DNA from mice with the indicated Aldh1a1 genotype. The identities of the different alleles are indicated on the right. (D) Western blot analysis of liver proteins (50 µg) from adult mice with the indicated Aldh1a1 genotype, using anti-RALDH1 (upper panel) and anti-RALDH3 (lower panel) polyclonal antibodies, showing the absence of RALDH1 (R1) and a normal amount of RALDH3 (R3) in Aldh1a1^L–/L– mice.