Figure 3. Projection neuron dendrite targeting in sema-2a sema-2b mutant flies.

(A–D) DL1 PN dendrites target normally to the dorsolateral DL1 glomerulus in wildtype (A) and sema-2a^−/− (B) or sema-2b^−/− (C) mutants. In sema-2a^−/− sema2b^−/− double mutants, DL1 dendrites split their dendrites between DL1 and an ectopic ventromedial position (D₁) or shift the entire glomerulus ventromedially (D₂). Green, GH146-GAL4 driven mCD8GFP in MARCM DL1 single cell clones. Red, synaptic marker nc82. Arrowheads: DL1 PN cell bodies. Scale bar, 50 µm.

(E–F) Quantification of DL1 PN dendrite targeting along the dorsolateral to ventromedial (E) and dorsomedial to ventrolateral axis (F). The antennal lobe is divided into 11 bins with bin 1 being most dorsolateral (E) or most dorsomedial (F) (see Komiyama et al., 2007). The fraction of total dendritic fluorescence in each bin is calculated for WT (blue) and sema-2a/2b^−/− double mutants (magenta). A scatter plot of the mean dendritic bin position of each antennal lobe is shown below for each condition. n=11 for WT and sema-2a/2b^−/− mutants. Error bars, standard error of the mean. Average positions: E: WT, 1.87±0.09; sema-2a/2b^−/−, 3.95±0.31. F: WT, 5.02±0.10; sema-2a/2b^−/−, 4.85±0.23. ***, P<0.001 by equal variance two-tailed T-test.

(G–H) Wildtype DL3 PN dendrites target the dorsolateral DL3 glomerulus (G). In sema-2a/2b^−/− double mutants, DL3 dendrites mistarget ventrally or ventromedially (H). Green, HB5–43-GAL4 driven mCD8GFP. Red, synaptic marker nc82.

(I) Quantification of DL3 dendrite mistargeting along the DL-VM (left) and DM-VL (right) axis for WT (blue) and sema-2a^−/− sema2b^−/− double mutants (magenta). Average positions along DL-VM axis (left): WT: 1.45±0.02, n=20; sema-2a/2b^−/−: 2.59±0.45, n=19. *, P<0.05 by equal variance two-tailed T-test. Average positions along DM-VL axis (right): WT: 5.36±0.13, n=20; sema-2a/2b^−/−: 6.75±0.28, n=19. ***, P<0.001 by equal variance two-tailed T-test.

(J–K) Wildtype VA1d and DA1 PN dendrites target the dorsolateral VA1d and DA1 glomeruli (J). Dendrites shift ventrally or ventromedially in sema-2a^−/− sema2b^−/− double mutants (K) antennal lobes. Green, Mz19-GAL4 driven mCD8GFP. Red, synaptic marker nc82.

(L) Quantification of VA1d+DA1 dendrite mistargeting along the DL-VM (left) and DM-VL (right) axis for WT (blue) and sema-2a/2b^−/− double mutants (magenta). Average positions along DL-VM axis (left): WT: 2.7±0.08, n=19; sema-2a/2b^−/−: 3.83±0.37, n=19. **, P<0.01 by equal variance two-tailed T-test. Average positions along DM-VL axis (right): WT: 6.59±0.16, n=19; sema-2a/2b^−/−: 7.52±0.21, n=19. **, P<0.01 by equal variance two-tailed T-test.

Either full (A–D) or partial (G,H,J,K) confocal stacks are shown. D, dorsal; V, ventral; M, medial; L, lateral.

Figure S3 shows that neither panneural PlexA knockdown nor whole animal PlexB loss-of-function affects dorsolateral dendrite targeting.