Fig. 1

 bao^s866 Mutants Undergo a Dramatic and Rapid Expansion of the Gut Lumen between 96 and 120 Hours Postfertilization

(A) Bright-field image of 120 hr postfertilization (hpf) wild-type (WT) and bao^s866 mutant larvae. Arrows point to the edges of the gut lumen.

(B and C) Confocal images of cross-sections of 120 hpf WT (B) and bao^s866 mutant (C) larvae. The arrow in (C) points to a delaminating cell. Red is F-actin and blue is DAPI; sb indicates swim bladder. Scale bars represent 50 μm.

(D and E) Dramatic shortening of microvilli (arrows) in bao^s866 mutant enterocytes observed by transmission electron microscopy at 120 hpf. Inset in (E) shows remnants of apoptotic cells found in the lumen. GC indicates goblet cell. Scale bars represent 10 μm.

(F–I) Rapid expansion of the gut lumen in bao^s866 mutants expressing histone 2A:GFP.

(F) Still images (lateral views) from a bao^s866 mutant selective plane illumination microscopy (SPIM) recording between 96 and 120 hpf showing first and last frames.

(G and H) Kymographs from bao^s866 mutant (G) and WT (H) gut. Lumen expansion in the mutant occurred in ~200 min; no cell division was observed.

(I) Still images (lateral views) from the bao^s866 mutant SPIM recording corresponding to the kymograph shown in (G).