Fig. 7. Tissue-specific rescue of the foi mutant phenotypes. In all cases, embryos are mutant for the endogenous foi gene (foi^20.71) and rescue experiments were conducted as described in the Materials and Methods. Gal4 indicates the tissue expressing the Gal4 transcriptional activator (meso, mesoderm; gc, germ cells). UAS indicates whether a UAS-foi expression transgene was present and which one. (A) Rescue of the foi gonad phenotype. Expression of foi in the mesoderm fully rescues the foi mutant gonad defect, while expression of foi in the germ cells shows no rescue. (B) Rescue of the foi tracheal phenotype. Expression of foi in either the trachea or mesoderm rescues the tracheal fusion defect. (C,D) Stage 15 gonads immunostained to reveal the germ cells (anti-VASA, red) and the gonadal mesoderm (anti-EYA, green). (C) foi mutant showing defective gonad coalescence. (D) foi mutant rescued by expression of HA-FOI (C-terminal tag) in the mesoderm. Coalescence is normal.