Fig. 6. The recruitment of fusomal membranes does not depend on Shot, Egl or microtubules, but the concentration of Rtnl1 into the oocyte does. (A-A") In germline clones of a null allele of shot (shot³) Rtnl1-GFP is still localized to the fusome, but does not concentrate into the oocyte. Germline clones are marked by the absence of GFP (green in A and as a single channel in A'; clones are indicated by the dotted lines). Rtnl1-GFP is also shown in green in A and also in the single channel in A'. As the germline clones lack GFP, Rtnl1-GFP distribution can be analyzed in these, but cannot be directly compared with adjacent wild-type germline cells. The cytoskeletal fusome is marked by Hts (red in A and as a single channel in A"). (B-D) In a heteroallelic combination of egl reported to be a null mutant, egl^WU50/egl^RC12, Shot (red in B) still localizes to the fusome and recruits the stable microtubule array marked by acetylated -tubulin (green in B), although Orb is completely mislocalized in all cysts (D). In this allelic combination, Rtnl1-GFP is recruited to the fusome at wild-type levels (C), but in the majority of cases the accumulation into the oocyte in region 3 of the germarium fails. (E-E") In the absence of microtubules in the germarium (by treatment of female flies with colchicine) Orb is completely mislocalized (red in E and as a single channel in E"), though some Rtnl1-GFP (green in E and as a single channel in E') still accumulates in the region of the fusome (white arrows), but it fails to concentrate in the oocyte. A-A",C and E-E" are stacks of confocal sections through the whole germarium, B and D are thick sections through the central portion of the germarium. Green arrows in E' point to the muscle sheet surrounding each ovariole that is also labeled by Rtnl1-GFP and partly visible in the projection. Bars, 10 µm.