Cell autonomous expression of EcR ^DN blocks astrocyte transformation and has additive effects in Beat-Va neurite pruning. (A–C) Astrocytes genetically manipulated with GMR25H07-Gal4 (a strong astrocyte Gal4 line) crossed to UAS-CD8::GFP (A) show a “wispy” morphology at wL3, (B) display many phagolysomes at 4 h APF (Yunsik et al., 2023, Preprint), and (C) are normally only faintly detectable by HE. (D–F) Astrocytes expressing a UAS-EcR^DN, labeled with mCD8::GFP at wL3 (D) showing their “wispy” morphology, which is retained at (E) 4 h APF, and (F) HE, indicating a failure to transform. (G and H)arm-LexA, LexAop-mCD8::RFP at (G) wL3 where normal astrocyte morphology is apparent, and (H) HE when astrocytes are no longer visible. (I and J) (I) When alrm-LexA drives a LexAop-EcR^DN in addition to LexAop-mCD8::RFP, astrocytes appear normal at wL3, (J) but then fail to transform at HE. Scale bars are 20 µm. (K–N) (K) Micrograph of a single cell MFCO clones at HE in the control condition, (L) when EcR^DN is expressed only in Beat-Va neurons, (M) when astrocyte transformation is blocked via astrocytic expression of EcR, and (N) when both neuronal and astrocytic EcR signaling is blocked. All scale bars are 20 µm.