Fig. 1. The four lia mutations cause exchanges or deletions of conserved amino acid residues of Fgf3 protein, leading to a complete loss of Fgf3 activity. (A) Amino acid alignment of Fgf3 proteins from zebrafish, rat, mouse and human. Conserved amino acids are boxed, amino acid residues mutated in the different lia alleles are highlighted in black, with the new amino acid residues indicated in red. The premature protein termination caused by the t24152 mutation is indicated with a star (^*). (B) Phenotypic classes (F1-F4) and frequencies (%) obtained upon injection of wild-type or mutant fgf3 mRNAs at concentrations of 0.1 or 10 ng/µl. F1 embryos are characterized by a loss of the eyes and a normal tail; F2 by a loss of eyes, fore- and midbrain, and a curled up, truncated tail; F3 embryos by a complete loss of head and tail; and F4 embryos by lysis around the 10-15 somite stage. Data were obtained in two independent experiments. n, numbers of scored embryos.