fbxw7 is the gene mutated by the vu56 allele. (A) Schematic representation of genetic mapping and sequencing results. The vu56 mutation mapped to a region of Chromosome 1 containing fbxw7. The vu56 mutation created an amino acid substitution within the second WD repeat of the predicted Fbxw7 protein. (B) Sequence traces from wild-type and vu56 mutant cDNAs. The vu56 mutation changed a G to an A, converting a BamHI restriction site to a HinfI site. (C) RFLP genotyping of homozygous wild type (+/+), heterozygous (+/−) and homozygous mutant (−/−) larvae. U = uncut, B = BamHI digest, H = HinfI digest. (D) RT-PCR analysis of fbxw7 mRNA splicing in control (Crtl) and fbxw7SSMO-injected (MO) 24 hpf embryos and 3 dpf larvae. Upper band in MO lanes (asterisks) indicates splice blocking products. (E) Sequence analysis of RT-PCR products from control embryos, which lack intron 4 sequence (dashed lines) and fbxw7SSMO-injected embryos, which retain intron 4 sequence. Underlined sequence is complementary to the splice-blocking morpholino. (F,G) Lateral images of 3 dpf uninjected control and fbxw7SSMO-injected larvae. Insets show corresponding bright field images. (H-I’) Transverse sections of 3 dpf uninjected control and fbxw7SSMO morpholino injected larvae showing Sox10 expression (red, arrowheads). Panels H’ and I’ show Sox10 labeling merged with olig2: EGFP (green). (J) Quantification of Sox10+ cells per section in control and fbxw7SSMO-injected larvae (n = 8 larvae each genotype; p = 0.0001). Error bars represent SEM.