Figure 5.

Ligand Capture and Local Release Contribute to Layer-Specific NetB Expression

(A and A′) In controls at 55 hr APF, NetB (blue) is enriched in the M3 layer; R8 axons terminate in this layer (double arrowhead in inset in A). La, lamina; Me, medulla.

(B and B′) fra knockdown (KD) in the eye using ey^3.5-FLP, act≫Gal4 FLPout transgenes: NetB localization in M3 is unaffected, despite the failure of R8 axons to extend into this layer (arrow in inset in B), suggesting that innervation by R8 axons is not required for maintenance of this layer.

(C and C′) fra eye and target area knockdown using ey-FLP, act≫Gal4 FLPout transgenes: NetB expression in M3 is strongly decreased, but not abolished; R8 axons show targeting defects (arrow in inset in C).

(D and D′) fra target area knockdown using ey-FLP, act≫Gal4 FLPout and ey^3.5-Gal80 and lGMR-Gal80 transgenes: NetB expression in M3 is decreased; R8 axons target correctly (double arrowhead in inset in D).

(E–H) Graphs present average NetB fluorescence intensities within white boxes (A–D′).

(I and I′) In controls, Fra (blue) is widely expressed in the medulla including the M3 layer (arrowheads).

(J and J′) fra target area knockdown using ey-FLP, act≫Gal4 FLPout and ey^3.5-Gal80 and lGMR-Gal80 transgenes: Fra expression is strongly decreased in the medulla neuropil including the M3 layer (arrowheads).

(K–L′) NP4151- and NP0831-Gal4 drive expression of the presynaptic marker UAS-syt^HA (blue) and GFP (green). Primary release sites of NetB-expressing neurons include the axon terminals of lamina neurons L3 in layer M3 (arrowheads) and of medulla neurons in the lobula (arrow, Lo). Lop, lobula plate. R cell axons are labeled with mAb24B10 (red).

Fra or NetB protein expression is shown in pseudocolor in (A′), (B′), (C′), (D′), (I′), and (J′) (see scale for values). GFP expression (green) marks the cells in (B), (C), (D), and (J), in which UAS-fra^IR is expressed. Scale bars, 20 μm.

See also Figure S5.