Fig. 2. Generation of claudin-11-deficient mice. (A) Restriction maps of the wild-type allele, the targeting vector and the targeted allele of the mouse Cld11 gene. The first ATG codon was located in the putative exon 1, which encoded the N-terminal portion (amino acids 1-75) of the claudin-11 molecule containing the first transmembrane domain and the first extracellular loop. The targeting vector contained a pgk neo cassette in its middle portion to delete exon 1 in the targeted allele. The position of the probe for Southern blotting is indicated as a bar. E, EcoRI; B, BglII. (B) Genotype analyses by Southern blotting of EcoRI-digested genomic DNA from wild-type (+/+), heterozygous (+/-) and homozygous (-/-) mice for the mutant Cld11 allele. Southern blotting with the probe indicated in A yielded a 5.8-kb and a 3.8-kb band from the wild type and the targeted allele, respectively. (C) Loss of Cld11 mRNA in the testis of claudin-11-defcient mice examined by reverse-transcription polymerase chain reaction. As a control, the hypoxanthinephosphoribosyl-transferase-encoding gene (HPRT) was equally amplified in all samples.