Expression of simScer\UAS.cXa under the control of Scer\GAL4sim.P3.7 results in the loss of the preoral commissures and reduced postoral commissures in the embryonic brain. The circumesophageal longitudinal connectives are thinner than normal.
Expression of simScer\UAS.cXa under the control of Scer\GAL4ey.PH results in a headless phenotype. Three classes of phenotype are seen; class I pharate adults lack all head structures derived from the eye-antennal discs, class II consists of eyeless flies which lack most head structures and both antennae and class III consists of eyeless animals with large parts of the head missing but one or both antennae present.
Scer\GAL4prd.RG1 mediated expression in wild type embryos causes a pair-rule larval cuticle phenotype. Segmentation defect may result in part from the inability of ectopic midline cells to generate cuticle structures and/or excessive cell death in regions expressing ectopic sim.