Fig. 4. Grk protein distribution in wild-type, grk^DC and cni mutant egg chambers. (A) Stage 10 wild-type egg chamber. Grk protein is concentrated at the anterodorsal corner of the oocyte in the vicinity of the nucleus. Some Grk can be seen in the follicle cells receiving the Grk signal. (B) Stage 10 grk^DC/grk^DC egg chamber. Grk protein is mislocalized to the interior of the oocyte. The staining appears patchy and granular, with high protein concentration near the nucleus. Grk is not detectable in the follicular epithelium. (C) Stage 10 cni^AR55/Df(2L)H60 egg chamber. Grk protein is distributed in a gradient with a high point near the posteriorly mislocalized oocyte nucleus and in a cortical ring at the anterior end of the oocyte adjacent to the nurse cells. There is no detectable Grk uptake into the follicular epithelium. (D) Immunoelectron microscopy of the anterodorsal corner of a stage 10 wild-type egg chamber. Grk immunogold staining (small black dots) can be detected in the oocyte (ooc) near the nucleus (nuc, arrows) and at the plasma membrane facing both follicle cells (fc) and nurse cells (nc). Grk is also present at the microvillous processes of the follicle cell surface (arrowheads) and within the follicle cells. Grk is absent from the cortex of yolk granules (yg). (E) Immunoelectron microscopy of the ventral posterior part of a heterozygous stage 10 grk^DC/CyO oocyte. Most Grk staining is associated with the cortex of growing yolk granules (arrows). (F) Immunoelectron micrograph of a stage 10 cni^AR55/Df(2L)H60 egg chamber. Grk staining is found scattered throughout the oocyte (arrows) but does not accumulate at yolk granules or the oolemma.