Figure 6. Wide-field Dm8 amacrine neurons are required for UV preference.

(A) Various ort promoter constructs containing different multispecies-conserved regions (C1–C3). The ort locus structure is as described in Figure 1E.

(B–D) Expression patterns of ort^C2-GAL4 (B), ort^C3-GAL4 (C) and ort^C2∩vGlut (D) drivers in adult optic lobes. These drivers were used to express the mCD8-GFP marker in different subsets of Ort-expressing neurons (see text for details). A few neurons in the lobula and lobula plate (arrowheads), which do not normally express Ort, were labeled by ort^C2-GAL4 and ort^C3-GAL4, respectively (B, C). (D) The combinatorial driver ort^C2∩vGlut labeled Dm8 as well as sparse L1 cells (arrowheads in lamina cortex). Photoreceptor axons visualized with MAb24B10 antibody (red); specific medulla and lobula strata immunolabeled with anti-FasIII (cyan). Scale bar: 20 µm in (B), for (B–D). (E–H) Restoring or blocking different subsets of Ort-expressing neurons affects UV/green preference. Intensity-response curves were measured as described in Figure 2.

(E) Sufficiency of ort^C2 and ort^C3 neurons for UV/green preference. Restoring the function to the ort^C2 neuron subset rescued UV preference in ort mutants while restoring it to the ort^C3 subset rendered a stronger green preference. ort^1/US2515, wild-type and negative control sev data are from Figure 2E.

(F) Requirement for ort^C2 and ort^C3 neurons for UV/green preference. Blocking the ort^C2, but not ort^C3, neuron subset in wild-type background reduced UV preference. ort^1/US2515, wild-type and negative control sev data are from Figure 2E.

(G) Requirement for, and sufficiency of, the Dm8 neurons for UV/green preference. Restoring Ort expression in the Dm8 neurons using the ort^C2∩vGlut driver rescued UV preference defects in ort or HisCl1 ort double-null mutants. Conversely, inactivating the Dm8 neurons caused a significant reduction in UV preference. ort^1/US2515, wild-type and negative control sev data are from Figure 2E.

(H) Histogram of the relative attractiveness of UV over green light (Attr_UV/G) calculated from (E–G). The differences between ort mutants and after ort function is rescued in ort^C2->Ort (or ort^C3->Ort or ort^C2∩vGlut->Ort) are statistically significant (*p<0.00001), as are those between the wild-type and ort^C2->shi^ts1 (or ort^C2∩vGlut->shi^ts1). Error bars indicate standard deviations.