jag1b, her9, and her6 redundantly regulate dorsal versus ventral identity. (A) jag1b;her6;her9 triple heterozygotes were intercrossed and six days post fertilization (dpf) larvae were stained with Alcian Blue and Alizarin Red to label cartilage and bone. The individuals were then genotyped, the viscerocrania were dissected and flat mounted then imaged. The opercle (op), branchiostegal ray (br), and cleithrum (cl) are indicated in the wild type control. The bony fusion between the opercle and the branchiostegal ray is indicated. Red arrows indicate expanded, fan-shaped branchiostegal ray. Asterisk marks stick-shaped op phenotype (B) Genotyped preps from A were scored for penetrance of expanded branchiostegal ray. Asterisk indicates that penetrance of this phenotype in jag1b-/-;her9+/-;her6-/- is significantly different from all other genotypes, where it is never observed. (C) jag1b;her6;her9 triple heterozygotes were intercrossed and 26 hours post fertilization (hpf) larvae were fixed for in situ hybridization experiments to label dlx5a expression. White arrows indicate ventral dlx5a expression, asterisks mark dorsally expanded dlx5a expression. Red arrow indicates reduced ventral dlx5a expression in triple mutants suggesting ventral-versus-dorsal identity reversal. This phenotype was observed on both sides of in 3/3 embryos examined with this genotype. Scale bars are 50 μm.
