The AB strain zebrafish were cultured at 28 ± 1°C. Embryos were cultured in E3 medium consisting of 5 mM NaCl, 0.17 mM KCl, 0.33 mM CaCl2, and 0.33 mM MgSO4. For whole-mount in situ hybridization (WISH), 0.0045% 1-phenyl-2-thiourea was added into E3 medium to prevent embryos from pigmentation started 24 h post-fertilization (hpf). Different stages of embryos were sorted and fixed following the guide of Kimmel et al. (1995).