Figure 3.
Ecdysone signaling mediates downregulation of Br in the SCs. (A-B) Expression of ecdysone activity reporter EcRE-lacZ showed a pulse of ecdysone activity from stage 9 in the anterior cells, including SCs. The increased expression of EcRE-lacZ (red in A, A’, white in A”) is in contrast to decreased Br expression (green in A, A’, white in A’”). Ecdysone activity peaks at stage 10a (red in B, white in B’), and no Br (green in B, white in B”) was detected. (C) In EcR-B1 function repressed clones (green in C, white in C’) created by the flip-out Gal4/UAS technique, SCs of a stage 10a egg chamber failed to flatten properly. (D) EcR repression driven by the SC-expressed A90-Gal4 (white in D) caused severe accumulation of SCs at the anterior. (E) Loss of EcR function in MbFCs (white in E) did not affect SC flattening and MbFC migration. (F) Introducing br RNAi in EcR-B1-repressed SCs partially restored proper SC flattening and MbFC migration. (G) Diagrams depict the accumulation of SCs in different genetic backgrounds. (H) The Accumulation Percentage (AP) was applied to measure the accumulation of SCs. Statistical differences of AP were observed between A90-Gal4 control (n=19) and A90-Gal4; UAS-EcR-B1DN group (n=39), A90-Gal4; UAS-EcR-B1DN and A90-Gal4; UAS-EcR-B1DN; UAS-br RNAi group (n=19), respectively. ***p<0.001. DAPI staining marks cell nuclei. Anterior is to the left. Bars, 20 μm.