Fig. 2

Phenotypic consequences of zebrafish ptc1 mutants. Homozygous ptc1^hu1602 mutants show a subtle somite phenotype at 32 hpf, where the average angle of the somite becomes more obtuse (A,B). At 72 hpf, ptc1^hu1602 mutants exhibit an eye phenotype where the pigmented epithelium is extended into the diencephalon. The similar phenotype described for the blw mutant is weaker compared to the ptc1^hu1602 mutant (C-E). The expression level of ptc1, a general readout for Hh activity, shows a mild increase in the blw mutant compared to wild type (F-H). The ptc1^hu1602 mutant shows a severely increased level of ptc1, where wild types, heterozygotes and mutants can be distinguished based on ptc1 levels (I-K). Additional to the difference in the strength of the eye phenotype, the activation of the pathway is significantly higher in ptc1^hu1602 mutants compared to blw mutants. An increased expression level of gli1 confirms an activation of the Hh pathway in the ptc1^hu1602 mutant (L-N).