Fig. 6. Analysis of epithelial polarity and SJ integrity in knk mutants. (A-D) The knk mutant tracheal epithelium displays normal levels and distribution of the two SJ proteins Fas3 (B) and Dlg1 (D), compared with the wild type (A,C). (E,F) TEM analysis of wild-type (E) and knk mutant (F) epidermis reveals a normal `ladder'-like SJ structure (arrows) in the mutants. (G,H) The apical marker Crumbs localizes normally along the apical cell surface in knk mutants (H), compared with the wild type (G). (I,L) Embryos homozygous for loss-of-function alleles of Fas2 and knk display additive reduced luminal 2A12 levels. Early stage 15 wild-type (I), Fas2 (J), knk (K) and Fas2;knk (L) mutant embryos labelled with antibody 2A12. The images were obtained with identical confocal settings, and show that luminal 2A12 levels are reduced in Fas2 mutants, reduced and unevenly distributed in knk mutants and absent in Fas2;knk^7A69 double mutants. The cellular 2A12 levels are, however, comparable. (M,N) The luminal Pio protein appears unaffected in knk mutant DT (N), compared with wild type (M), as shown by co-labelling for Pio (green) and 2A12 (red). Scale bars: 5 µm in A-D; 10 nm in E,F; 7 µm in G-N.