Fig 2

(A) Bright-field images show that the mycn mutants lacked swim bladder at 4 dpf but appeared at 5 dpf. All embryos are shown in lateral view. (B) Abnormal pharyngeal arch development was observed in mycn mutants via Alcian blue staining; images show the head region of WT and mycn mutant embryos at 5 dpf (ventral view). (C) Intestinal lumens in WT and mycn mutant embryos at 5 dpf shown by ET33J1: EGFP reporter (lateral view). (D) Fluorescence signals show the morphology of the whole intestines in WT and mycn mutant embryos at 7 dpf via DCFH-DA treatment (lateral view); statistical analysis of intestine length was showed in right. (E) Expression of shha and hand2 by WISH showing fin bud development in WT and mycn mutant embryos at 30 hpf (dorsal view). (F) Morphology of the whole intestine visualized via HE staining for the WT and mycn mutant embryo sections at 4 dpf. Black arrows indicate goblet cells in the WT intestines. Sections were cut along the sagittal plane. (G) Expression of ifabp by WISH showing intestines in WT and mycn mutant embryos at 3 dpf (dorsal view). (H) Diagram of the rescue plasmid construction. Overexpression of mycn specifically in endoderm cells was driven by sox17 promoter. (I) Expression of ifabp in WT (2 images on the left) and mycn mutant embryos (2 images on the right) at 3 dpf. The injected embryos are labeled with “inj” at the bottom of the image. Scale bars: 200 μm (A-F), 50 μm (G). The data underlying this figure can be found in S1 Data. DCFH-DA, 2′,7′-Dichlorodihydrofluorescein diacetate; dpf, days postfertilization; HE, hematoxylin–eosin; hpf, hours postfertilization; ifabp, intestine fatty acid–binding protein; WISH, whole mount in situ hybridization; WT, wild-type.