(A) Pax3 is expressed in the dorsal neural tube and somites of WT E8.5 embryos. Neural tube closure fails in wsnp mutants, leading to the widely separated stripes of Pax3 expression; no somite expression of Pax3 is detected in the mutants. (B) Immunostaining for SOX2 expression in transverse sections of E8.5 neural epithelia. While the wild-type neural tube at trunk level is closed, the wsnp neural epithelium remains flat and fails to close. (C) Sonic hedgehog (Shh) expression at E8.5, showing a continuous midline in WT embryos and a discontinuous midline in wsnp mutants. (D) The Poglut1 protein includes a signal peptide, a CAP10 domain and an endoplasmic reticulum retention signal (KTEL). The wsnp allele harbors a splice site mutation that leads to multiple spliced products (either including a part of the intron 3 or skipping exon3), which both disrupt the enzymatic domain. Exon 4 is deleted in the Poglut1
Δ allele leading to a frameshift and a premature stop codon. The line for the Poglut1
Δ allele indicates where the wild-type protein sequence stops. (E) Meox1 is expressed in the E8.5 paraxial mesoderm, which is segmented in WT, but not in wsnp homozygotes or in Poglut1
Δ/wsnp transheterozygous embryos, demonstrating that wsnp fails to complement Poglut1
Δ. (A, C, E) Dorsal views, anterior up. Scale bars = 150 μm.