Fig. 2.
IMP is required for the first cleavage of Notch. (A,A′) Cut expression in a stage 7 egg chamber containing an imp7 follicle cell clone marked by the loss of RFP (magenta). Cut expression persists in the mutant cells (n=32). (B,B′) A stage 8 egg chamber containing an imp7 follicle cell clone stained for Cut (n=41). Cut is lost from the majority of mutant cells. (C,C′) Hnt expression in a stage 7 egg chamber containing several imp7 follicle cell clones marked by the loss of RFP. Hnt is expressed in the wild-type cells, but not in the mutant cells at stage 7 (n=28). (D,D′) A stage 8 egg chamber containing imp7 follicle cell clones stained for Hnt. The mutant cells have turned on Hnt at this stage (n=47). (E-F′) E(spl)m7lacZ expression in stage 6/7 and stage 7 egg chambers containing imp7 follicle cell clones marked by the loss of RFP. E(spl)m7lacZ is expressed at much lower levels in imp mutant cells than in wild-type cells at stage 6 (n=12), but at similar levels at stage 7 (n=21). (G,G′) A stage 7 egg chamber containing an imp7 MARCM clone marked by the expression of GFP (magenta) and stained for Hnt (green). The mutant cells do not express Hnt at stage 7 (n=27). (H,H′) A stage 7 egg chamber containing an imp7 MARCM clone expressing UAS-NICD stained for Hnt (green). Hnt expression is rescued by the expression of the NICD (n=21). (I-L″) Localisation of the NICD (I-J″) and the NECD (K-L″) in wild-type early-stage egg chambers and egg chambers containing imp mutant clones. Both NICD and NECD are enriched at the apical side of wild-type follicle cells until stage 6 when they are downregulated as a result of Delta signalling. NICD (J-J″; n=38) and NECD (L-L″; n=27) are not downregulated in imp7 mutant cells (marked by the loss of RFP). Dashed lines indicate imp mutant clones. Scale bars: 10 μm.