Fig. 3.

JNK is required for endoderm cell rearrangements. (A-H) The prospective gut endoderm was injected with two lipophilic dyes (DiI, red; DiO, green) in anterior-posterior (A-P labeling; A-D) or dorsal-ventral (D-V labeling; E-H) orientations at stage 24. Labeled embryos were exposed to DMSO (B,F), SP600125 (C,G) or Rockout, RO (D,H), from stage 35-46; whole guts were dissected to visualize the final longitudinal distribution of each dye (indicated by red or green brackets). Labeled cells become distributed along the axis of the gut tube in DMSO controls (B,F), but fail to rearrange in the presence of SP600125 (C,G) or Rockout (D,H). (I-L′) Deep endoderm cells of the prospective gut tube were injected with DiI (red) at stage 24 to achieve ‘Center labeling’, as shown (I, stage 37). Labeled embryos were then exposed to DMSO (J,J′), SP600125 (K,K′) or RO (L,L′) from stages 35 to 46, bisected and counterstained with phalloidin (green). In DMSO controls (J,J′), the labeled cells have radially intercalated and are incorporated within the gut epithelium. In the presence of SP600125, labeled cells are confined to a central ‘core’ of endoderm (dashed circles in K.K′) or to a radial quadrant of stratified cells (dashed lines in K). In the presence of RO, labeled cells span the entire diameter of the tube (L,L′). (M) The frequency of individual guts with the DiI label contacting only the basement membrane (black), occupying a radial quadrant of the gut tube (blue), spanning the gut diameter (red) or confined only to the center (yellow) after exposure to DMSO, SP600125 or RO. Scale bars: 50 μm.