Figure 10
The EcR pathway is required for peripheral dendrite development. (a) Control class IV ddaC MARCM clone. (b) usp2 MARCM clone showing reduced ddaC dendrite branches. (c) Quantification of the mean number of branch ends per neuron, comparing wild-type (WT) to usp2 MARCM clones. The asterisk indicates significant reduction (t-test, P < 0.000001). (d) Control ddaC neuron (genotype: UAS-mCD8::GFP/+;;ppk1.9-GAL4/+). (e) Expression of RNAi-inducing UAS-IR-EcR, targeting all EcR isoforms. (f) Expression of a dominant-negative EcR (EcR-DN). (g) The graph on left shows the mean number of branch ends per neuron for all genotypes tested, including those co-expressing UAS-Dicer2 (Dcr2), a component of the RNAi machinery that can potentiate the RNAi effect [88]. The graph on right shows the mean branch density in ddaC class IV neurons. Pairwise comparisons (ANOVA, Tukey, P < 0.0001) determined that EcR RNAi significantly reduced both branch number per neuron and branch density (single asterisks). EcR-DN further reduced branch number and density to levels lower than both controls and RNAi (double asterisks). The analysis revealed that the RNAi-induced reduction of branch density (right graph) was not enhanced by coexpression of Dcr2. (h) Control ddaC neuron (same genotype as (d)) in first instar larva (28–30 hours AEL). (i) Expression of EcR-DN (same genotype as (f)). (j) EcR-DN reduced branch number in first instar larvae (asterisk, t-test, P < 1e-7), but did not influence the field area (control = 11,349.7 ± 324.6 μm2 versus EcR-DN = 12,261.0 ± 372.7 μm2, t-test, P = 0.07). Error bars in (c,g,j) indicate standard error. Anterior is left and ventral is down. Scale bars: (a,b,d-f) = 100 μm; (h,i) = 25 μm.