Figure 1.

Fra Is Expressed in R Cells and the Optic Lobe

(A) Schematic of the Drosophila adult visual system highlighting the organization of the medulla neuropil into ten layers (M1–M10), and the neuron subtypes relevant for this study. sg, satellite glia; meg, medulla glia.

(B) Schematic illustrates of R8 and R7 axon-targeting steps to temporary and final M3 and M6 layers during metamorphosis.

(C–F′) In the retina, Fra (blue) is expressed along the cell body membranes of R8 cells at 24 hr (arrowheads in C′) and in rhabdomeres at 42 and 55 hr APF (arrowheads in E′ and F′). Fra is expressed in R1–R6 rhabdomeres at 42 hr (arrows in D′). R8 cells are labeled with caps-Gal4 and UAS-cd8GFP (green).

(G–J′) In the medulla (Me), Fra (red) is enriched in the temporary layer of R8 axons at 24 and 42 hr (arrowheads in G′ and H′) and in the emerging and final M3 layer at 42 and 55 hr and in adults (arrows in H′, I′, and J′). In the lamina (La), Fra is enriched in R1–R6 axons at 42 hr (asterisk in H′). sg and meg glial subtypes are Fra positive (double arrowheads in H′, I′, and J′). Lo, lobula; Lop, lobula plate.

(K–L′) Target area-specific knockdown reveals Fra expression in R8 axons at 24 and 42 hr (arrowheads in K′ and L′).

(M and M′) Knockdown of fra using repo-Gal4 reduces expression in glia (double arrowheads in M′), but not in the M3 layer (arrow in M′), and does not affect R cell axon targeting.

R cells are labeled with mAb24B10 (red in C–F′ and K–L′; green in G–J′, M, and M′).

Scale bars, 5 μm (C–F) and 20 μm (G–M).

See also Figure S1.