Fig. 8. Loss of shg inhibits vein morphogenesis.

ap^Gal4 was used to express either GFP (A–C,G,I), or GFP together with a UAS-shg-IR transgene (D–F,H,J) in dorsal wing cells from 0–36 hours APF. (A–F) Optical cross-sections through vein L4 and the posterior margin of 36 hour APF wings are shown. Eliminating shg expression (compare A′ to D′) impairs the ability of vein cells to form a vein lumen (compare A,B,C to D,E,F). Arrow in A″ points to the L4 vein cells which have constricted along the apical/basal axis to form the dorsal portion of a vein lumen, while shg-ir expressing L4 vein cells do not contrict (arrow D″). Additional examples of dorsal L4 cells expressing GFP (B,C), or shg-IR (E,F) are shown. (G) Depletion of shg expression does not affect the pattern of vein/intervein identity, as measured by DSRF expression. (H–K) TEM analysis indicates that shg-IR expression affects adherens junction morphology. Apical adherens junctions found in control wings (arrowheads H) are nearly eliminated in shg-IR expressing cells (arrowheads I). Basal adherens junctions (arrows J) are similarly reduced (arrows K). Scale bars indicate 500nm.