Fig. 6.

JNK is required for endoderm microtubule (MT) architecture. (A-R) Embryos were exposed to DMSO (A-C′,J-L), SP600125 (D-F′,M-O) or Rockout (RO; G-I′,P-R) from stage 35 through to stage 40 (A,D,G), 42 (J-R), 43 (B,E,H) or 46 (C,C′,F,F′,I,I′), and transverse sections were stained with α-tubulin (green) to reveal MT architecture, β-catenin (red) to indicate cell-cell adhesive contacts and/or DAPI to show nuclei (blue). (C′,F′,I′) Higher magnification images of the boxed areas in C,F,I, respectively. Apicobasally oriented MT arrays (arrows) are evident in DMSO control guts (A-C′,K), but MT polymerization is disrupted in the presence of SP600125 (D-F′,N), especially in the inner cell population (asterisks, F,F′). Although MT arrays are predominantly apicobasally oriented in RO guts at stage 42 (Q), abnormal foci of MTs eventually form throughout the gut (arrowheads, H-I′). (S-U) Polar coordinate diagrams show the orientation of the MTs in DMSO, SP600125 and RO guts (stage 42). Black bars show the alignment of individual MTs with respect to the apicobasal axis (AB) of the relevant cell, whereas the length of the bar indicates the relative numbers of MTs oriented at that angle. Bars in yellow sectors indicate MTs oriented within 30° of the apicobasal axis, whereas bars in orange sectors indicate MTs that deviated outside of this region. In DMSO (S) and RO (U) guts, most MTs are oriented in parallel (within the yellow sectors); however, the angles of individual MTs are more variable in guts exposed to SP600125 (T). Scale bars: 50 μm.