Figure 6.

Acj6 represses the larval receptor gene Or45b in the adult maxillary palp. A, Response profiles of pb2C (in acj6⁶) and Or45b (in the empty neuron system). n = 6 for pb2C; n = 19 for Or45b. Error bars indicate SEM. B, In situ hybridization to Or45b mRNA in wild-type and acj6 maxillary palps. The arrowheads indicate labeled cell bodies. C, Effects of altering an Acj6 site on Or45b-GAL4-driven GFP expression. Or45b-GAL4 is not expressed in the wild-type maxillary palp but is ectopically expressed in the acj6⁶ maxillary palp. Mutation of the Acj6 site at −392 caused expression in the wild-type adult, mimicking the effects of the acj6⁶ mutation. Replacement of the Acj6 site at −392 with another Acj6 site, one that directs activation of Or46a, yielded the same expression pattern as that driven by Or45b-GAL4. Two independent lines were examined for each genotype. The Or46a site contains two Acj6 consensus sequences that overlap by 1 bp and are on opposite strands of the DNA. D, Model for dual mode of regulation. Acj6 activates transcription (left) or represses transcription (right) depending on the presence of other proteins that bind in the vicinity.