A substitution mutation in Dll1 leads to situs inversus and posterior truncation.

(A) Whole mount view of Dll1E26G and wildtype embryos. Note the shorter tail in the mutant. (B) An A-to-G mutation causing a glutamine-to-glycine substitution in the Dll1E26G mutant protein. (C) The mutation is localized in the N1 domain. SP, signal peptide; N1, N-terminal domain 1; N2, N-terminal domain 2; DSL, Delta-Serrate-Lag2 domain; EGF repeat, epidermal growth factor-like repeats; TMD, transmembrane domain; PDZL, PDZ (postsynaptic density 95, PSD-85; discs large, Dlg; zonula occludens-1, ZO-1) ligand motif. (D-I) H&E stainings on transverse sections at E9.5. The asterisk in E marks reversed looping compared to wildtype (D). NT, neural tube; Ht, heart. The arrow in G indicates an ectopic neural tube (F). Irregularly shaped neural tube (asterisks) and somites (arrows) in Dll1E26G mutants (H,I). Som, somites; Nc, notochord.