Figure 6.

Evidence that the MRS drives y expression in a small number of cells in the third instar CNS. (A) Diagram of the y locus in the newly described mutant y⁶⁰¹⁴. The y⁶⁰¹⁴ mutation is caused by a P{GawB} insertion at +23 bp relative to the start of y transcription. This P-element insertion contains the Gal4 sequence, allowing sequences upstream of the element, including the MRS, to control expression of a UAS-GFP reporter in F₁ offspring. (B) Fluorescent microscope image of a third instar CNS from the genotype y⁶⁰¹⁴; UAS-nu.GFP/+ with the P{GawB} driving nuclear-localized GFP. We observed expression in four cells in the same location as the Yellow⁺ cells shown in Figure 5 (open arrowhead). Ectopic expression of GFP in a few cells throughout the CNS was also seen (see results). Generally, the strongest GFP expression was seen in the four putative Yellow⁺ cells. (C) Magnification of the four cells next to the white arrow in B.