Fig. 2. Syph is dynamically expressed in LE cells and filopodia during DC. (A-E) Dorsal view of an embryo expressing Syph-RFP in an En (striped) pattern during DC. Boxed region in A and equivalent regions of B-E are shown at higher magnification in A'-E'. Note that Syph accumulates in LE cells as the epithelial sheets meet (arrows in A'), and decreases after midline fusion. (F-F''') Syph accumulates in puncta at the apex of LE cells expressing GFP-Syph (arrow in F). These puncta accumulate in filopodia as the epithelial sheets meet (arrowhead in F,F') and disperse after cell fusion (brackets in F''-F'''). See Movie 1 in the supplementary material. (G-J) Syph localization in filopodia. Boxed region in G and equivalent regions of H-J are shown at higher magnification in G'-J'. Levels of Syph are dynamic within a growing filopodia: yellow lines in G'-J' follow the movement of a Syph puncta within a single filopodia. See Movie 2 in the supplementary material. (K-L'') Filopodia in LE cells in an embryo expressing both Syph-GFP (K,L; green in K'',L'') and mRFP-actin (K',L'; red in K'',L'') in an En pattern. As epithelial sheets approach each other, both Syph and actin accumulate in the LE cells and in their filopodia (K-K''), before resolving to a thin band of expression at the dorsal-most edge after fusion (L-L''). Scale bars: 20 µm in A-E'; 5 µm in F-L''.