Fig. 4. uif mutant embryos have normal tracheal patterning and maturation, and have intact septate junctions.

(A, B) 2A12 staining of stage16 uif^2B7/+ and uif^2B7 embryos demonstrates that tracheal patterning as well as dorsal trunk tube length and diameter are normal in uif mutants at this stage of development. (C–F) Confocal optical sections of uif^2B7/+ and uif^2B7 embryos stained with chitin binding probe (CBP) show a continuous chitin cable in the lumens of wild type and uif mutant animals at stage 16 (insets in C and D show xz projections of the dorsal trucks) that is completely cleared by mid-stage 17 (insets in E and F show optical cross sections of the dorsal trunk that can be visualized near the posterior of the animals). Note that CBP staining still outlines the apical surface of the dorsal trunk in mid-stage 17 mutant embryos indicating the presence of a chitinous cuticle. (G–J) uif^2B7/+ and uif^2B7 embryos stained with antibodies against the septate junction protein Coracle (Cor) show the correct localization of this protein in an uif mutant trachea (H) and salivary gland (J). In all panels, anterior is to the left. Scale bars = 50µm in A–B; 10µm in C–J.