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. Author manuscript; available in PMC: 2016 Mar 4.
Published in final edited form as: Neuron. 2015 Mar 4;85(5):1013–1028. doi: 10.1016/j.neuron.2015.02.003

Figure 1. Identification of Toll-6 and Toll-7 as Wiring Specificity Molecules in an RNAi Screen.

Figure 1

All images are single confocal sections of adult antennal lobes, with magenta showing neuropil staining and other colors showing axons of specific ORN classes and dendrites of specific PN classes as indicated. N is number of antennal lobes tested.

(A) Schematic of RNAi screen. A pan-neuronal C155-GAL4 drives UAS-RNAi of predicted transmembrane and secreted molecules. Dendrites of two PN classes, DA1 and VA1d, are labeled by Mz19QF > QUAS-mCD8GFP. Axons of two ORN classes, VA1d and VA1v, are labeled by two different markers driven directly from odorant receptor promoters. This four-color screen can in principle identify phenotypes in four processes listed on the right.

(B) In wild type, dendrites of Mz19-QF+ PNs and axons of VA1d and VA1v ORNs target to their glomeruli in stereotyped positions in the lateral antennal lobe. D, dorsal; L, lateral (scale bar is 10μm).

(C) Pan-neuronal RNAi knockdown of toll-6 causes dorsomedial (shown here) or dorsolateral (not shown) mistargeting of VA1d ORN axons and PN dendrites (arrow).

(D) Pan-neuronal RNAi knockdown of toll-7 causes VA1d ORN axons and PN dendrites to mistarget to a medial position.

(E) Wild-type VA1d ORNs target axons to the VA1d glomerulus ventral to the DA1 glomerulus (dashed circle).

(F) In toll-6 mutants, VA1d ORN axons mistarget either dorsomedially (shown here) or dorsolaterally (see Figure 4I) in 50% of cases (N=20).

(G) In toll-7 mutants, VA1d ORN axons partially mistarget to a medial position. Mistargeting was observed in all antennal lobes examined (N=24).

(H) Quantification of VA1d ORN axon mistargeting in toll-6 mutants, shown as percent dorsomedial (grey) and dorsolateral (black) mistargeting.

(I) Quantification of VA1d ORN axon mistargeting in toll-7 mutants. Top, normalized fluorescence intensity was binned along the lateral (bin 1) to medial (bin 10) axis of the antennal lobe and averaged across all animals (top graph). Bottom, mean intensity of VA1d ORN axons (each dot represents one fly; t-test, P< 0.0001) is shifted medially in toll-7 mutants (bottom graph).

(J) Schematic of the domain organization of Toll-6 and Toll-7 proteins. Toll-6 and Toll-7 both have extracellular leucine-rich repeat (LRR) domains and intracellular conserved Toll-interleukin receptor (TIR) domains. CF and NF, C-terminal and N-terminal LRR cysteine cluster motif. TM, transmembrane domain.