Fig. 1. Subcellular localization of Src42A. Boxed regions are enlarged in insets or separate panels. (A-F2) Ovaries stained for Src42A (green) and E-cad (magenta). Asterisks indicate oocytes; arrowheads indicate polar or invading border cells. Some cystocytes in region 2a/b exhibited transient but strong Src42A expression (A). In subsequent stages, relatively strong Src42A signals associated with E-cad signals became evident along the follicle/germline-cell boundary (D2). E-cad signals are shown only in enlarged panels. Nurse cell membrane E-cad signals surround ring-canal-Src42A signals (C1,C2). During oogenesis stages 6-9, oocytes incorporated Src42A into the cytoplasm (B,D,E) and began accumulating it on the oocyte surface (D2,D3). (F1,2) Membrane localization of E-cad-free Src42A was clearly seen at stage 10b, when centripetal cells strongly expressed Src42A and E-cad (arrow indicates oocyte membrane). (G1-V) Embryos stained for Src42A and E-cad. Src42A and E-cad signals are colored in green and magenta, respectively (except in U). Stages are shown in the bottom left-hand corner. In stage 2 embryos, membranous Src42A (I) signals scarcely associated with E-cad. (G1-3) Panels showing three phases of membrane extension in stage 5 embryos. Arrowheads indicate extending membrane tips marked with Src42A. (J) At stage 7, apical signals for Src42A and E-cad in furrow-forming or invaginating cells (H2,K) became stronger than in others (H1). At mid-late-stages, E-cad-free Src42A expression occurred between ectodermal and mesodermal cell-layers (see arrows in L). Src42A and E-cad signals colocalized at the apical tips of mesectoderm cells (M1,M2) and the apical surface of ectodermal tubular structures such as stomodeum (N), salivary gland (P), hindgut (Q,R) and Malpighian tubules (R). Malpighian tubules are hindgut protrusions (Skaer, 1993) and, unlike hindgut enclosed with the visceral mesoderm (inset in R), are not associated with visceral mesoderm. Arrows in R show that basal Src42A signals abruptly have disappeared with Malpighian-tubule protrusion. (O) Src42A and E-cad signals at stage-13 leading edge. (S) E-cad/Src42A colocalization at fusion points of dorsal trunk of trachea (see arrowheads). Arrows, Src42A signals in the tendon, rich in integrin (Martin-Bermudo and Brown, 1996). (T,U) E-cad and Src42A expression in CNS. E-cad signals were detected only in midline cells (see arrowheads). Fas2 expression (magenta) (U) shows Src42A expressed in axons, optic lobe and Bolwig's organs. (V) Src42A signals in gonad. hg, hindgut; np, neuropile; pc, pole cells; pm, posterior-midgut primordium; pr, proctodeum primordium; st, stomodeum; tr, trachea; vm, visceral mesoderm; cl, clypeus; ec, ectoderm; me, mesoderm; sg, salivary gland; mt, Malpighian tubule; m, muscle; bo, Bolwig's organ; ol, optic lobe.