Fig. 2

Filopodial outgrowths depend on UNC-34 (Ena/VASP) and UNC-115 (abLIM). A Representative images of PVD dendrite morphology in wild-type, unc-34(null), and unc-115(null) animals at the L4 stage. Yellow rectangles indicate locations of magnified views on the right. B Quantification of number of quaternary branches in a region 100 µm anterior to the PVD cell body. Statistical comparison was performed using Brown-Forsythe ANOVA with Dunnett’s multiple comparisons test (****, p < 0.0001; n = 9 worms for wild-type and unc-34; n = 10 worms for unc-115). C Live animal imaging of developing PVD dendrites in wild type, unc-34 mutant, and unc-115 mutant. Cyan arrows indicate filopodia that emerge in wild type. Yellow asterisks indicate swellings, which fail to initiate filopodia in unc-34 and unc-115 mutants. Scale bar is 5 µm. D Representative traces showing growth of individual dendrites of indicated genotypes. E and F Quantification of filopodia (E) and swelling formation (F). Statistical comparison was performed using Brown-Forsythe ANOVA with Dunnett’s multiple comparisons test (****, p < 0.0001; ns, p > 0.05; n = 15 worms for wild-type; n = 9 worms for unc-34; n = 11 worms for unc-115). G Quantification of tip swelling width. Each data point is the averaged width of swellings measured from 5 to 10 dendrites within a single worm. Statistical comparison was performed with a two-tailed Mann–Whitney test (**, p < 0.01; n = 7 worms for wild-type; n = 8 worms for unc-34). H and I Quantification of standard deviation (SD) (H) and average (I) of dendrite branch growth speed. Lower SD indicates more consistent, gradual increases in length. See Methods for details. Statistical comparison was performed using Brown-Forsythe ANOVA with Dunnett’s multiple comparisons test (****, p < 0.0001; ***, p < 0.001; n = 24 branches for wild-type; n = 21 branches for unc-34; n = 9 branches for unc-115)