FIG. 1.

Targeting of mouse nkd1. (A) Schematic of the Nkd1 protein above the genomic region, with exons numbered 1 to 10 and the direction of transcription designated by the arrow. The asterisk designates the position of the stop codon introduced into exon 5. Homologous recombination (dashed lines) replaced exons 5 to 10 with the IRES-lacZ/neo cassette. Enzyme sites: V, EcoRV; R, EcoRI. aa, amino acids. (B) Southern blotting of mouse tail DNA cut with EcoRV (top) or EcoRI (bottom) from the indicated genotypes and probed with the 5′ (top) or 3′ (bottom) external probes as designated in panel A. (C) PCR genotyping with tail DNAs from mice of the indicated genotypes amplified with primers specific for the wild-type (WT) and nkd1^lacZ (KO) chromosomes. (D) Northern blotting of adult lung mRNAs from mice of the indicated genotypes probed with nkd1 exon 10 probe (top) and then stripped and reprobed with gapdh as a loading control (bottom). Note that +/− has approximately half the signal from the major 1.8-kb band of +/+ mice and that −/− lung tissue has no specific hybridization signal. (E) Western blotting of extracts from 15.5-dpc nkd1 +/+, +/−, and −/− mouse embryos. Note the reduction of the ∼60-kDa band in the +/− lane and its absence from the −/− lane (arrow). The arrowhead designates a cross-reactive band that confirms equal loading in each lane.