Fig. 7. Expression of FGF genes in ich mutant embryos and rescue of phenotype by FGF. (A-M) Mutant embryos derived from ich^-/- females and wild-type embryos derived from ich^+/- females are shown as animal pole views. Initial expression of fgf3 and fgf8 is strongly reduced at sphere stage in mutant embryos (B,D) compared with wild-type embryos (A,C), where the double arrows mark dorsal expression. (E-M) Expression of fgf3 continues to be reduced in mutant embryos at 30% (E,F) and 50% epiboly (I,J). By contrast, fgf8 expression is detected at 30% epiboly around the margin (G,H), and continues in mutant and wild-type embryos at 50% (K,M). (N-O) Overexpression of fgf3 (compare N with O) or fgf8 (compare N with P) partially rescues ich embryos (asterisks indicates rescued embryos). (Q) Rescue of ich by injection of FGF genes and ß-catenin. Both fgf3 and fgf8 injections resulted in partial rescue of mutant embryos. RNA encoding the nuclear localized form of ß-galactosidase (nß-gal) or zebrafish ß-catenin was injected into ich embryos as a negative and positive control, respectively. Phenotypic classification was slightly modified from Kelly et al. (Kelly et al., 2000): class 1 embryos are the most ventralized, lacking trunk and head; class 1a develop partial trunk and spinal cord but no hindbrain or more anterior structures; class 2 develop spinal cord and hindbrain but not midbrain, forebrain or eyes; class 3 develop incomplete anterior brain and eye structures; class 4 develop a complete AP axis but no notochord; class 5 appear normal at 24 hpf.