FIG. 1.
Gene targeting of the Btg2 locus. (a) Diagram showing the Btg2 WT genetic locus, the corresponding targeting construct, and the resulting targeted mutant allele. Two exons are indicated by shaded boxes. Both 5′ and 3′ probe regions for genomic Southern screening are indicated, as are the expected sizes of fragments from WT and mutant Btg2 loci. Restriction enzyme sites for BamHI (sites labeled B), EcoRI (E), HindIII (H), PstI (P), and XbaI (X) are indicated. Restriction enzyme sites in brackets indicate the nullification of the recognition sequence. Neomycin resistance (neor) and thymidine kinase (tk) cassettes are in the opposite direction of the Btg2 gene. KO, knockout. (b) Genomic Southern analysis of Btg2+/− crossing. Genomic DNA from WT and Btg2+/− and Btg2−/− mice was digested with EcoRI and BamHI and subsequently hybridized with 5′ and 3′ probes. (c) Northern blot analysis of Btg2+/− crossing. Note the absence of the Btg2 transcript in the kidney of the Btg−/− mutant.