Fig. 5. GFP-Vkg basement membrane is assembled cell non-autonomously. (A) Confocal image showing the anterior region of an ovariole. Note that BM is present at all stages of egg chamber development. (B) Scheme of the FLP-FRT-mediated clonal analysis used to generate mosaic egg chambers containing clones of cells expressing either no copies (0; blue color code), one copy (gray color code) or two copies (red color code) of GFP-Vkg. In this scheme, the clonal marker is a nuclear GFP (nls-GFP, green). (C) A mosaic egg chamber containing several clones of cells expressing 0, 1 or 2 copies of GFP-Vkg. Note the uniform basement membrane. In particular, cells that do not express GFP-Vkg (blue lines) have a normal BM, indicating that GFP-Vkg is not contributed autonomously to the BM by follicle cells. (D) Another example in which a large clone of cells expressing two copies of GFP-Vkg (red line) abut cells expressing no copies of GFP-Vkg (blue line). In this case, as well, there is no change in the apparent thickness or staining of the BM. (E) The same egg chamber double labelled with phalloidin-TRITC (red) to outline the cell boundaries. (F-G') Two egg chambers in which a big clone of cells that do not express GFP-Vkg (blue line) is adjacent to cells expressing 2 copies of GFP-Vkg (red lines). In these mosaic egg chambers, the GFP-Vkg BM is uniform. (C-E) The clonal marker is a nuclear GFP; (F-G') the clonal marker is a Myc tag (anti-c-Myc shown in red). Scale bars: in A, 10 µM; in C 10 µM for C-E; in F 10 µM for F-G'.