Figure 3

UAS-ara-expressing clones interconnect with one another. Clones (green) were detected by expression of UAS-GFP, except in H where anti Ara/Caup was used. Counterstaining (in red) was Actin (A-E, K, K'), anti RhoGEF2 (G), anti Ara/Caup (I, J) and (in purple) anti Engrailed (H). (A, B) Mid third instar wing discs with clones overexpressing UAS-ara and UAS-GFP or UAS-GFP alone, respectively, induced 48 hours earlier. Magnified views of the areas within squares are shown in A' and B'. Interconnections between the clones noticeable in A and A' (arrowheads) are absent in B, B'. In more mature third instar discs most clones overexpressing UAS-ara (C) are arranged in an interconnected net, but not so the clones not overexpressing the Iro-C gene (D). (E) xy confocal section of the wing pouch region of a disc bearing interconnected UAS-ara clones. (F) A stack of xy images of the same disc is shown in a stereo projection selecting only the UAS-ara expressing cells. Asterisks identify same areas in E and F. UAS-ara expressing cells tend to form "walls" separating large territories of non-expressing cells. In x, y sections these walls appear as thin strings. (G) A very long string (arrow) connecting two large separate clones. (H) An anterior compartment clone (green) and a posterior compartment clone (white) displaying connecting cells (arrow). Cell nuclei were stained with anti Ara/Caup antibody. Purple: Engrailed posterior marker. Picture modified from [16] (data courtesy of R. Diez del Corral). (I, J) xy and z optical sections, respectively, of a connecting string. Cell nuclei of overexpressing cells are shown in yellow or orange. Note that the string can be only one cell thick (arrow). (K, K') z optical section accross a single cell-wide wall. The green channel brightness has been strongly enhanced in K' to show the body of the cell(s) from apical to basal.