Fig. 2. EGL-43 is required for AC/VU specification and AC invasion. Images of the gonad and vulva region of hermaphrodites in the mid-L3 (2 and 4-cell P6.p stage; A-F,I,J) and the early L4 (8-cell P6.p stage; G,H,K-N) stages. (A-H) Nomarski (left), fluorescence (right) and overlay (center). (I-N) Nomarski (top), fluorescence (bottom) and overlay (middle). Transgenic animals that contain (A,B) lin-3::GFP (syIs107, for the AC), (C,D) cdh-3::GFP (syIs50, for the AC), (E,F) lag-2::YFP (syIs128, for the DTC), or (M-N) sparc::GFP (syIs113, for the basement membrane) were soaked in the control or egl-43 dsRNA solution. (G) In control RNAi-treated animals that carry a gain-of-function mutation (n137) of lin-12, the AC is transformed into a VU cell. Additional vulval cells (Muv phenotype) express cdh-3::GFP (green) at early L4. (H) In animals treated with egl-43 RNAi, two ACs expressing cdh-3::GFP (green, arrows) are present owing to the suppression of activated LIN-12 during AC/VU specification. However, egl-43 RNAi does not suppress the Muv phenotype caused by the activated LIN-12. (I) With control RNAi, the basement membranes are interrupted (between the arrowheads) underneath the AC (expressing cdh-3::GFP in white), and the basolateral side of the AC crosses through the hole in the basement membranes and penetrates between central 1°-fated vulval cells. (J) In animals treated with egl-43 RNAi, two partially overlapping ACs (expressing cdh-3::GFP in white) cannot cross the unbroken basement membranes. A distinct line representing the juxtaposed gonadal and ventral epidermal basement membranes is visible under Nomarski optics, separating the AC from the P6.p granddaughters. (K) The basolateral portion of the AC invades between the central P6.pap and P6.ppa cells. Because some vulval cells also express cdh-3:GFP at early L4, the cytoplasmic GFP signals in the AC (arrow) and vulval cells overlap. (L) In animals treated with egl-43 RNAi, the GFP signal in the ACs is separated from those in the vulval cells because the ACs (arrows) could not invade into the vulval epithelium. The basement membranes between gonad and vulval epithelium are (N) intact in the egl-43 RNAi or (M) lost (between the arrowheads) in the control RNAi underneath the AC (arrow) when viewed by sparc::GFP (white).