Figure 1.
Targeted mutagenesis of CMAS. (A) The NLS (K198RPRR) in exon 4 of Cmas was targeted by mutations marked in blue (nls). A neomycin resistance (neo) cassette flanked by loxP sites (triangles) was inserted into intron 4 and a diphtheria-toxin (DT) cassette was inserted into intron 3. Correct homologous recombination was detected by 5′ outside and 3′ outside primers combined with neo primer pairs. A 1-kb fragment generated by inside primers was used as a control. (B) PCR products from targeting vector (TV), targeted allele (TA) from Cmasnls neo embryonic stem cells, and wild-type (wt) embryonic stem cells and DNA marker. (C) P0.5 homozygous Cmasnls mutants were indistinguishable from wt with respect to gross anatomy and coat color. nls refers to the mutant Cmasnls allele lacking the neo after CRE-mediated excision.