Fig. 7. grain expression is under the control of Notch signaling. (A) In wild type, Vnd is expressed in the pCC interneuron, but this expression is lost in spdo^G104 mutant (B,B'). (C,G) Vnd is derepressed in the aCC motoneuron when Notch signaling is activated using RN2-GAL4/UAS-Notch^ICD (intracellular domain of a constitutive activated form of Notch). The arrow indicates aberrant axonal projection (probably from aCC and/or RP2). (D) In grn mutants, derepression of Vnd is not observed in aCC (or in RP2) suggesting that grn does not repress Vnd in this sibling neuron. (E) In wild type, Grn is not expressed in pCC. (F,H) In spdo^G104 mutants, Grn (and grn^GAL4) is derepressed in the pCC neuron. Grn is also derepressed in the RP2sib; 4 Eve-positive neurons (observed in B) are indicated by a vertical bar and an asterisk. (G,I) Activation of Notch (RN2- GAL4/UAS-Notch^ICD) led to a loss of Grn (and grn^lacZ) expression in aCC and RP2. Arrowheads and asterisks indicate aCC and RP2, respectively.