(A) Schematic of the shha WT allele (+), non-mutagenic, conditional-trap allele (ct), and inverted mutagenic allele (m), and primers sites. (B) Genotyping PCR result of single embryos from incrosses of ubb:Cre-GFP; shhact/+ fish. (C) Pectoral fin phenotype of WT and heterozygous and homozygous mutagenic embryos in B. Embryos that did not carry ubb:Cre-GFP transgene were analyzed (Cre-GFP−). Pectoral fin development was normal in all WT embryos (0 abnormal in 5 analyzed) and most heterozygous mutants (1 moderately abnormal in 7 analyzed; p=0.3774, Fisher's exact test), but severely hampered in all homozygous mutants (3 abnormal in 3 analyzed; p<0.01, Fisher’s exact test). (D) Semi-qRT-PCR analysis of shha expression in WT and heterozygous and homozygous mutagenic embryos. The number above each lane in the gel picture indicates the Embryo ID in B. (E) Densitometric quantification of the PCR result in D. The data represent the mean ± SD (**p<0.01; Mann–Whitney U test).