Figure 2

her9 is required for efficient mineralization. (A) Exon diagram for her9 indicating the untranslated regions (UTR) and the regions predicted to encode the basic helix-loop-helix (bHLH) and Orange domains. The location of the early stop encoded by the her9^co66 allele is indicated. (B, C) Zebrafish heterozygous for her9 were pairwise 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, flat mounted, and then imaged. The following craniofacial skeletal elements are indicated in the wild-type individual: opercle bone (op), branchiostegal ray (br), maxilla (mx), entopterygoid (en), ceratobranchial 5 (cb5) bone, teeth (t), and the cleithrum (cl). Arrow in C indicates the unmineralized, Alcian Blue-positive opercle. Scale bar is 50 μm (D, E) The neurocrania from the same experiments as B and C were dissected, flat mounted, and then imaged. The parasphenoid bone (ps) and notochord (n) is indicated in the wild-type individual. Arrow in D indicates the shadow bone where the mineralized parasphenoid would be observable in wild types. (F, G) Enlargements from D and E. Arrow indicates the unmineralized shadow bone. Arrowhead denotes osteoblast-shaped cells surrounding the shadow bone. Scale bar is 50 μm (H, I) Enlargements from (B, C). The adductor operculi and the levetor operculi muscles (ao/lo) are indicated. Arrow in I indicates the unmineralized, Alcian Blue-positive opercle with the adductor operculi and the levetor operculi muscles (ao/lo) attached. (J) The penetrance of her9 mutant-associated phenotypes observed in 6 dpf larvae for each genotype are indicated. Asterisk indicates significant difference (p<0.05) in penetrance between the indicated genotype and wild type by Fishers exact test.