Fig. 1. Disruption of the Ndst1 gene by targeted recombination. (A) Maps of the wild-type Ndst1 locus, the Type II `floxed' allele and a Type I deletion allele, obtained after breeding of Type II mice with ZP3-Cre mice. Lox-sites located in intron sequences are shown as triangles. (B) PCR analysis. Deletion of exon 2 in Ndst1^–/– mice yields a 350 bp product, whereas wild-type mice produce a 250 bp amplification product. Heterozygous mice yield both amplification products. (C) Southern blot analysis of DNA. DNA digestion using restriction endonucleases HindIII and BglII yields a 2.6 kbp (wild type) and a 3.2 kbp (Ndst1^–/–) band. (D) PCR analysis of the same samples as in (C). (E) Western blotting of total embryo extract after SDS-PAGE. Samples were detected by an affinity-purified rabbit-anti-mouse Ndst1 antiserum (Grobe and Esko, 2002). The weak signal seen in the knockout lane is due to cross-reactivity with Ndst2-4, all of which are expressed in the developing embryo (Aikawa et al., 2001). (F-I) Detection of Ndst1 expression in the developing embryo. (F,H) Whole-mount in situ hybridization in E11.5 wild-type embryo showed strongest expression (blue stain) in the forebrain and frontonasal/maxillary processes (arrows). (G,I) Ndst1^–/– embryo probed with an antisense riboprobe showed no reactivity. (J-M) Immunohistochemical detection of Ndst1 expression in E16.5 embryos using the affinity-purified rabbit-anti-mouse Ndst1 antiserum (Grobe and Esko, 2002). Ndst1 protein is strongly expressed (brown) in frontonasal mesenchyme (J) and telencephalic walls (L). In the developing face, hair follicles show the highest expression levels (arrow). (K,M) The hair follicles and telencephalic walls are not stained in Ndst1^–/– tissues. CP, cortical plate; IZ, intermediate zone; VL, ventricular layer. (M) There is a lack of stratification in the Ndst1 mutant cortex. Scale bar: 10 µm in J; 100 µm in L.