Fig. 6. Targeted expression of dominant-negative dARNT prevents lamina neurons from assembling lamina columns. (A-C) NP6099-GAL4 expression in the optic lobe visualized using UAS-nlsGFP (green) and anti-Dac (magenta in merged image B). NP6099-Gal4 is also expressed in a small part of the most posterior eye disc, including in about 10 ommatidia (arrowhead in C). R axons are visualized by 24B10 (magenta in C). (D-F) A dominant-negative form of dARNT inhibits the incorporation of lamina neurons into the assembling domain; Dac, magenta and R axons, white. 3D reconstruction of Dac expression in D is shown in F. Lamina neurons are almost never seen in the assembling domain (F, arrow in D). (G-I) Effect of a dominant-negative form of dARNT expression is suppressed by co-expression of sim; Dac, magenta and R axons, white. 3D reconstruction of Dac expression in G is shown in I. Lamina neurons are incorporated in the assembling domain (arrow in G) and lamina columns as in the wild type.