Figure 1.

Generation of the Ghsr-IRES-Cre allele by gene targeting. A. Schematic shows the generation of the Ghsr-IRES-Cre knock-in mouse line by homologous recombination. The IRES-Cre cassette was inserted 3 bp downstream of the GHSR stop codon (TGA) in Exon 3. Binding sites for Southern blot probes used to detect correctly-targeted genomic DNA (after restriction digest with BamHI) are shown. The mice were crossed to Flp1 recombinase mice to remove the frt-Neo-frt cassette that had been included in the targeting construct to find neomycin-resistant ES cell clones. B. PCR analysis of genomic DNA obtained by tail biopsies of representative mice carrying two copies of the wild-type Ghsr allele (“WT”), mice homozygous for the modified knock-in Ghsr-IRES-Cre allele (“HOM”), and mice with one copy of each of the alleles − heterozygotes (“HET”).