Fig. 1

Hoxb1b is required for hindbrain lumen morphogenesis. (A) Schematic of wild-type (Hoxb1b) and mutant (Hoxb1b^b1219) protein domains of Danio rerio hoxb1b, with Antenapedia-type hexapeptide (AHP), DNA-binding homeobox domain and designated premature stop codon in Hoxb1b^b1219 mutant protein. (B-C22) Abnormal anterior hindbrain lumen morphology at r3/4 in hoxb1b^-/- compared with wild type at 22 hpf. (B) ZO-1 (apical tight junction) immunostaining; (C) Gt(Ctnna-Citrine)^ct3a (adherens junctions; live embryos). C2-C22 are progressively deeper z-sections of the dorsal view in C; C2 is a sagittal reconstruction at r3/4. Note duplicated lumina in the dorsal hindbrain (red arrows). Colored arrowheads in C2 indicate planes of subsequent panels. White arrowheads and white arrows in B and C indicate neural tube lumen abnormalities. In B, lower panels are higher magnifications of boxed areas in upper panels. (D) Onset of r3/4 hindbrain morphology defects at 14, 16 and 23 hpf in hoxb1b^-/- compared with wild-type hindbrain development. White arrows point to lumen discontinuities. Anterior-posterior axis marked by double arrows in all panels.