Fig. 5

Analysis of oogenesis of DlattP-DlK2R-HA/Df flies. A, B Expression of Lqf-GFP, Gbe + Su(H) and Dl::mCherry in wildtype ovarioles. The red arrows point to egg chambers in stages 5–7 where Dl is up-regulated. The white arrows in A highlight the up-regulation of expression of Lqf/Epsin in the oocyte of maturing egg chambers. The arrowhead in A points to the constant expression of Gbe + Su(H) in the follicle epithelium, most prominent close to the oocyte. C, D Expression of Gbe + Su(H) in the follicle epithelium of egg chambers of Dl^attP-Dl-HA/Df (C) andDl^attP-DlK2R-HA/Df (D) flies. The arrows points to the expression of Gbe + Su(H), which is strongly reduced in the Dl^attP-DlK2R-HA/Df egg chambers. Note the fusion of the egg chambers in the DlattP-DlK2R-HA/Df ovariole highlighted with the arrowhead in D. E, F Trans-endocytosis of the YFP-Notch ECD in the egg chambers of Dl^attP-Dl-HA/Df (E) and Dl^attP-DlK2R-HA/Df (F) ovarioles. It is best seen in the developing oocyte of egg chambers, highlighted with the arrows in (E). The trans-endocytosis of the ECD is dramatically reduced or absent in the Dl^attP-DlK2R-HA/Df oocytes (F, arrows). G, H Clonal analysis of the function of lqf in the female germline. The loss of lqf function dramatically reduces the trans-endocytosis of YFP-NECD in the oocyte. The arrowheads point to the oocyte of the egg chambers. H Magnification of the egg chambers of the region highlighted with the arrow in G. Note that the oocyte of the younger wildtype (smaller) egg chamber already accumulated YFP-NECD, while no YFP-NECD can be detected in the lqf-mutant oocyte of the adjacent, older chamber. I–J’mib1 function is not required during signalling of Dl from the germline to the follicular epithelium. Clonal analysis of the function of mib1 in the female germline. Expression of Cut in a wt ovariole (I, I’) and an ovariole carrying egg chambers with a mib1 mutant germline (J, J’). I, I’ Expression of Cut is down-regulated during stages 5–7 as a consequence of Dl signalling from the germline. The arrow points to an egg chamber in stage 6/7 that expresses Cut in the follicle epithelium, the arrowhead to an adjacent older egg chamber in stage 8/9 where Cut expression has been terminated because of the activation of the Notch pathway. J, J’ The arrow in J points to an egg chamber with a mib1 mutant germline expressing Cut, the arrowhead highlights an mib1 egg chamber in stage 8/9, which has terminated Cut expression despite the lack of mib1 function in the germline. This indicates that Dl can sufficiently signal to the epithelium despite the lack of mib1 function. In contrast, the ectopic stripe induced by Fng in Dl^attP-DlK2R-HA/Df discs was much shorter, confirming a substantial reduction of the signalling activity of Dl^attP-DlK2R-HA, compared to Dl^attP-Dl-HA or endogenous Dl (Fig. 4J, K, arrow, quantification in L)