Fig. 2. Arm is dependent on endogenous Arm to activate Wg signaling, while S10 is not. arm^043A01 germline clones made using the FLP recombinase system expressing either Arm or S10 using the GAL4/UAS system. (A) Confocal images of the four embryos obtained when arm^043A01; ArmGAL4/+ germline clones were crossed to Arm. En stripes are shown in red. Sxl antibodies were used to detect female arm/+ embryos (blue). Arm expression is shown by -HA staining (green). (B) Confocal images of embryos (arm^043A01; ArmGAL4/+ crossed to S10) showing the En stripes (-En, red), and lack of Sxl expression in these male embryos (arm/Y, blue). (C) Phase contrast images of arm^043A01; ArmGAL4/+ crossed to either S10 or Arm. The percentages are the approximate frequency with which the phenotype was observed over the course of three independent experiments. Cuticle preparations from the arm^043A01/Arm cross show approx. 25% naked (n=43), approx. 25% wild-type (n=36), and approx. 50% severe arm phenotype (n=78), consistent with arm/+; Arm/ArmGAL4 leading to naked cuticle, arm/+; Arm/+ leading to wild-type cuticle, arm/Y; Arm/ArmGAL4 and arm/Y; Arm/+ both leading to the severe arm phenotype. Cuticle preparations from the arm^043A01/S10 cross show 50% naked (n=105), 25% wild-type (n=57), and 25% severe arm phenotype (n=51), consistent with arm/+; S10/ArmGAL4 and arm/Y; S10/ArmGAL4 both leading to naked cuticle, arm/+; S10/+ leading to wild-type cuticle, arm/Y; S10/+ leading to the severe arm phenotype.