FIGURE 2.
jj263 locus encodes the zebrafish ift122. A, genetic map of the jj263 locus and the exon/intron structure of the ift122 gene. The ift122 locus was mapped on zebrafish chromosome 8 in the vicinity of a genetic marker Z8703. B, domain structure of the zebrafish ift122 protein and the mutation of the jj263 allele. The N-terminal WD40 repeats and the C-terminal TPR domain were indicated. The position of the ift122jj263 mutation is indicated with an arrow. This mutation produces a premature stop codon resulting in a 62-amino acid truncated product of ift122. C, sequencing trace data for the wild-type (left) and jj263 allele (right). The tyrosine residue at position 63 was changed to stop codon in the jj263 mutant. D and E, rescue by injection of IFT122 mRNA into embryos from crosses between jj263 heterozygotes. D, percentages of larvae that display pronephric cysts at 5 dpf following injection of GFP mRNA or IFT122 mRNA into embryos. E, images of ift122 mutant larvae at 5 dpf following injection of GFP (left panel) or IFT122 mRNA (right panel). Pronephric cyst formation is partially eliminated in homozygous ift122 mutants by injection of IFT122 mRNA (right panel). Arrowheads point to pronephric cysts. F, RT-PCR analysis of ift122 expression in embryos at several developmental stages. Maternal ift122 transcript was detected in embryos at 4–16-cell stage. A housekeeping gene, glyceraldehyde-3-phosphate dehydrogenase (gapdh), was used as a loading control. Three different concentrations of cDNA templates (1×, 0.2×, and 0.04×) were used.