Fig. 4. syph-deficient embryos exhibit delayed and mis-matched
epithelial alignment during DC. (A-E'''') Confocal
micrographs showing dorsal view of an embryo expressing actin-GFP
(A-C'''') or DE-cadherin-GFP (D-E'''') under the control
of the En-Gal4 driver (striped pattern) that were injected with buffer alone
(A-A'''',D-D'''), with Syph dsRNA#1
(B-B'''',E-E'''), or with Syph dsRNA#2 (C-C'''')
undergoing DC. Syph RNAi-injected embryos expressing the actin-GFP reporter
complete DC but show mismatching of stripes, whereas those expressing the
cadherin-GFP reporter display mismatched, puckered stripes and delayed or
incomplete hole closure (see oval in E''''). Note: the intense
actin-GFP labeled filopodia on the upper side of the embryo in
B'-B''' are observed as a result of the orientation of the embryo,
not as a result of the Syph RNAi. (F-G) Confocal micrograph of a single
optical plane from two time points (F, F', and G, respectively) of Syph
RNAi-injected embryo expressing En-Gal4 driven actin-GFP showing a single cell
from one epithelial sheet (dashed line) contacting across eight to ten cells
from the opposite epithelial sheet. (H-J') BG2 cell co-stained
for Syph (H) and DE-cadherin (I) show co-localization of the two proteins in
filopodia (J). (H'-J') Higher magnification view of the area boxed
in J for H-J, respectively. (K-M) High magnification dorsal view of
embryos expressing DE-cadherin-GFP under the control of the En-Gal4 driver
(striped pattern) that were injected with buffer alone (K) or with Syph
dsRNA#1 (L,M) undergoing DC. Note accumulation of GFP-cadherin at the
dorsalmost side of the LE cells and the long filopodial extensions in control
(arrowhead, K) embryos. Syph-deficient embryos that exhibit epithelial
mismatching do not accumulate GFP-cadherin on the dorsal-most side of their LE
cells or appreciable filopodia (M), whereas Syph-deficient embryos that can
still match their epithelial sheets display an intermediate phenotype with
some dorsal edge GFP-cadherin accumulation and lamellipodia-like projections
from their LE cells (arrowheads, L). See Movie 3 in the supplementary
material. Scale bars: 20 µm in A-E''''; 10 µm in F-M.