Knockdown of arl13b impairs posture, locomotion, and cerebellar morphology in zebrafish larvae. A Wild-type sibling larvae remain vertically oriented at 5 days post-fertilization (dpf), with both eyes visible from a top view (arrows). B In contrast, larvae injected with arl13b MO (subthreshold dose, 7.3 ng) often lie on their side at the bottom of the dish, with only one eye visible (arrows). Note that the body of the subthreshold-dose arl13b morphants are relatively straight and only slightly curved. C Statistics of the posture of zebrafish larvae at 5 dpf. D Wild-type larvae perform stereotyped spontaneous swimming with small bending angles. E The arl13b morphants (subthreshold dose, 7.3 ng) swim slower and exhibit greater bending angles. F–H Immunostaining with acetylated tubulin antibody outlines the cerebellum of larvae at 3 dpf. Comparing the dorsal view of wild-type embryos (F) with arl13b mutants (G) reveals morphological defects of the cerebellum (arrows). The cerebellar defects were also present in embryos injected with arl13b MO (H) (cb, cerebellum). I Statistics of the embryos with morphological defects of the cerebellum. The number of embryos examined in each condition is indicated above each column. A–E, Scale bar 1 cm. F–H, Scale bar 100 μm.