Functional impairment of the ciliated organs in Rer1p morphant embryos. (a) Defective otolith formation in the inner ear of SMO. (b) Reduced or absent optokinetic response of 4.5-dpf SMO. The relative angle of eye rotation is shown for a control and two SMO larvae (n > 10). (c) Impaired retinal activity as measured by ERG in 4.5-dpf SMO; mean ± SEM is represented by shading. Decreased photoreceptor (PR) response and concomitant ON bipolar response (n ≥ 16). (d) Directional fluid flow in the KV is absent in the SMO as shown by fluorescent bead tracking (see Videos 3 and 4). Colored tracks show individual bead movements. (e) Randomization or loss of expression of Nodal antagonists lefty1 and lefty2 in SMO, ATGMO, and UTRMO as well as in DFC-specific injection of ATGMO and UTRMO at 20 hpf. Bars indicate percentages of embryos with expression on either side, both sides, or absent (n ≥ 90). UI, uninjected. (f) Reversal or absence of heart looping in SMO at 48 hpf. Bars indicate percentages of normal, reverse, or no heart looping. (g) Dorsal view of Alcian-stained cartilage of zebrafish heads. Arrowheads point to changes in pharyngeal cartilage chondrocyte number/arrangement; morphometric differences indicated by arrows are quantified in h. Means ± SEM (c) or SD (h); *, P < 0.05; **, P < 0.01, Wilcoxon rank sum test (c) or Student’s t test (h).