Figure 4. Off-track (Otk) is an Acj6 executor for instructing PN dendrite targeting.

(A) Criteria of Acj6’s cell-surface wiring executors. Loss of either Acj6 or its cell-surface wiring executor would lead to similar dendrite mistargeting. Supplying back the cell-surface wiring executor of Acj6 would rescue acj6 mutant phenotype.

(B and C) Expression of Otk in in a subset of discernible PN types at 42–48 hr APF in wild-type (B) or acj6 mutant (C) brains. Antennal lobe (outlined in yellow) and the DA4m (GH146− adPN), VA5 (lPN), and DL1 (adPN) glomeruli are outlined. GH146-FLP was used to express FLP in the majority of PNs.

(D) Quantification of Otk expression in developing PNs of wild-type (n = 9) and acj6-mutant (n = 8) animals. Fluorescence intensities were normalized to the GH146-FLP negative DA4m glomerulus in each antennal lobe. Mean ± s.e.m. *: p < 0.05; **: p < 0.01 (two-tailed t-test; p-values were adjusted for multiple comparisons using Bonferroni’s method). Note that the fluorescence intensity is always lower in deeper (more posterior) sections due to tissue scattering, so the absolute intensity cannot be compared across different PN types.

(E) Dendrites of wild-type DL1 single-cell clones innervate exclusively the posterior DL1 glomerulus (n = 18).

(F) acj6^−/− DL1 single-cell clones mistarget to both nearby glomeruli and a distant anterior glomerulus (n = 21). Yellow arrowhead, mistargeted PN dendrites.

(G) otk^−/− DL1 single-cell clones phenocopy acj6^−/− (n = 25).

(H) acj6^−/− DL1 dendrite mistargeting phenotypes were partially rescued by overexpressing otk (n = 16).

(I and J) Quantification of DL1 single-cell clones that mistargeted at a distance (I) and locally (J). p-values of Chi-squared tests are shown on plots.

Scale bars, 20 μm. D, dorsal; L, lateral. Arrow, PN axons.

See also Figures S5.