Figure 1.

Disruption of the H1R gene in mouse ES cells and generation of mutant mice. (a) Schematic diagram of the strategy used to target the H1R gene. Top line, genomic structure of the H1R gene in wt. The closed box represents the entire coding region of H1R gene. Middle line represents the targeting plasmid vector linearized at a unique SalI site. Neomycin-resistant (neo^r) gene with polyadenylylation signals driven by thymidine kinase promoter is shown by open box. The transcriptional orientation of the neo^r gene is opposite to the H1R gene. Bottom line represents the structure of the inactivated H1R gene after a correct homologous recombination. (b) Southern blots of tail DNA from the offspring of germ-line chimeras generated by blastocyst injection with the targeted ES cells. Tail DNA was extracted and digested with EcoRI and hybridized with probe A. Three genotypes, wt (+/+), heterozygote (+/−), and homozygote (−/−), are shown. Rehybridization of the same filter with a probe D confirmed that the 5′ half of H1R gene was absent from the genomic DNA of homozygous mice.