Setdb2 restricts dorsal organizer formation and regulates left–right asymmetry through suppressing Fgf8 activity. (A–F) WISH analyses of organizer markers flh (A and B), gsc (C and D), and chd (E and F) in the 5-MM control and setdb2 MO2-injected embryos at 6 hpf. Double-headed arrows denote territories of dorsal organizer. Embryos are animal views in the Upper panels, dorsal views in the Bottom panels. (G–I) WISH analyses of fgf8 expression (G and H) in the 5-MM control and setdb2 MO2-injected embryos at 6 hpf and effects of fgf8 overexpression on the dorsal organizer development as revealed by flh expression (I). Embryos are animal views in panels G and H (Upper) and I and dorsal views in panels G and H (Bottom). (J–M) WISH analyses of flh in the 6-hpf embryos injected with 5-MM control (J), setdb2 MO2 (K), setdb2 MO2 plus dominant-negative fibroblast growth factor receptor (dnfgfr) mRNAs (L), and setdb2 MO2 plus fgf8 morpholino oligonucleotides (M). (N) Statistic analyses of heart laterality marker cmlc2 and asymmetric gene southpaw in 6-hpf embryos injected with setdb2 MO2 and setdb2 MO2 plus fgf8 morpholino. Embryos are animal views in the Upper Panels and dorsal views in the Lower Panels.