Fig. 6

Transgenic expression of CASK⁺ significantly improves the bushy phenotype. Neurite-arbor morphology parameters from 3 div larval CNS neuronal cultures. Box-plot distributions depicted as in Fig. 3. Significance levels: *, p < 0.05; **, p < 0.005; ***, p < 0.0005; ****, p < 0.00005. a-d Neither individual transgene, UAS-controlled wild-type full-length CASK cDNA or the neuronal driver, elav-Gal4^C155, improved the bushy phenotype of CASK-mutant (Δ18/Δ18) neurons. Three genotypes were compared: w/w; + ; Δ18/Δ18 (n = 104; magenta); w/ + ; UAS-CASK⁺/ + ; ∆18/∆18 (n = 104; gray); and elav-Gal4^C155 w/ + ; + ; ∆18/∆18 (n = 105; light blue). a Both transgenes caused modest reductions in total neurite length, i.e., worsening the phenotype. b Territory area was mildly reduced by UAS-CASK⁺ only. c Higher-order branch number was not affected by either transgene. d Branch density, the most distinctive feature of the bushy phenotype, was not affected by either transgene. e–h Driving expression of transgenic CASK⁺ in neurons significantly improved all four parameters of the bushy phenotype. Three genotypes were compared: w/w; + ; Δ18/Δ18 (n = 105; magenta); elav-Gal4^C155, w/ + ; UAS-CASK⁺/ + ; Δ18/Δ18 (n = 104; bright blue); and w/w; + ; Ex33/Ex33 (CASK control; n = 105; aqua). e Total neurite length. f Territory area. g Higher-order branch number. h Branch density. Strong but incomplete transgenic rescue is consistent with the dosage-sensitive nature of the bushy phenotype