Fig. 3

Defects of exocrine pancreas formation in both mor^ha4/ha4 and Ddx46^{hi2137/hi2137} mutants are rescued by the overexpression of Ddx46 mRNA but not mutated Ddx46 mRNA.

(A) Scheme of the Ddx46 protein structure. The yellow, red, and orange boxes indicate the N-terminal, DEAD-box helicase, and C-terminal domain, respectively. Mutations were introduced into the Ddx46 protein; in Ddx46-I942S, an isoleucine in the C-terminal domain of Ddx46 was changed to serine, which is the same mutation as that in the mor^ha4 mutant; in Ddx46-K402A, GKT in motif I, which is important for ATPase activity in Ddx46 homologues, was changed to GAT. (B–I) All dorsal views, anterior to the top. The expression of try, a molecular marker for the exocrine pancreas, was examined using whole-mount in situ hybridization at 3.5 dpf. The try expression in the exocrine pancreas was markedly reduced in egfp mRNA-injected mor^ha4/ha4 (C) and Ddx46^{hi2137/hi2137} mutants (F) compared to egfp mRNA-injected control larvae (B, E). The try expression was rescued in the Ddx46 mRNA-injected mor^ha4/ha4 (D) and Ddx46^{hi2137/hi2137} mutants (G), whereas no rescue was achieved by the overexpression of Ddx46-I942S (H) or Ddx46-K402A (I) mRNA into Ddx46^{hi2137/hi2137} mutants. Control larvae-sibling WT or mor^ha4/+ larvae (B–D), sibling WT or Ddx46^hi2137/+ larvae (E–I)-had normal phenotypes.