arl13b and sec10 interact synergistically in cilia-related phenotypes. (A–H) Gross phenotypes of zebrafish embryo morphants at 3 d postfertilization (dpf) (A–D) and 6 dpf (E–H), on lateral view, after injection of MOs for arl13b and/or sec10. A synergistic interaction resulting in small eyes (arrow), pericardial edema (asterisk), and tail curvature (arrowhead) was observed upon coinjection of suboptimal doses of 2 ng of arl13b MO plus 7.5 ng of sec10 MO at both 3 and 6 dpf (D and H, respectively), which do not result in an abnormal phenotype when injected alone (B, C, F, and G); n = 535. (I) Histogram showing quantification of the effect of MOs at 3 dpf. Coinjection of suboptimal doses of 2 ng of arl13b MO plus 7.5 ng of sec10 MO results in a significant increase in the percentage of abnormal phenotypes (*p < 0.001) compared with injection of the MO alone (2 ng of arl13b MO or 7.5 ng of sec10 MO). Scale bars, 1 mm.