HYLS-1 is dispensable for cilia maintenance. (A) Schematic of the method used to degrade HYLS-1 specifically in ciliated neurons. (B) Amphid cilia structural integrity as assessed by dye filling. Dye-fill phenotype expressed as percentage of wild-type complement is shown. hyls-1 mutants display strong defects because of compromised axoneme assembly. These are rescued by expression of GFP:HYLS-1 (Student’s t test; P < 0.0001). Degron-mediated degradation of GFP:HYLS-1 after onset of ciliogenesis does not impair dye filling (Student’s t test; P = 0.57). Error bars are 95% confidence interval. n > 50 animals per condition. (C) Loss of GFP:HYLS-1 because degron-mediated degradation occurs from the threefold stage. Control animals not expressing degron are shown for comparison. Some HYLS-1 foci remain in L4, presumably because of lack of expression of the degron in those neurons or inaccessibility of the GFP epitope. Number of foci/amphid bundle ± 95% confidence intervals (n = 5–15 amphids per condition) is shown. (D) hyls-1 mutants display defects in targeting mKate2:DYF-19 to the ciliary base in amphid neurons. DYF-19 targeting is rescued in animals expressing GFP:HYLS-1 and the degron, despite late loss of HYLS-1. Transition zone marker mNeon:CCEP-290 is shown as a point of reference. (E) hyls-1 mutants display defects in IFT trafficking, shown using CHE-11:mKate2. IFT trafficking is restored in animals expressing GFP:HYLS-1 and the degron. (F) Tomographic slice through the amphid channel in L4-stage larvae of wild type, hyls-1 mutants, and hyls-1 mutants expressing both GFP:HYLS-1 and the degron. The marked axoneme extension defects in hyls-1 mutants are not observed in animals expressing both GFP:HYLS-1 and the degron. Bars: (C–E) 10 µm; (C, insets) 2 µm; (D and E, insets) 3 µm; (F) 100 nm.