Fig. 1

The bozozok locus encodes the Nieuwkoid/Dharma homeodomain protein. (a) Comparison of the genomic sequence of nieuwkoid/dharma from DNA isolated from homozygous wild type (*AB strain) and homozygous boz^m168 indicates a single base-pair substitution in the nieuwkoid/dharma ORF that changes W⁷⁰ to an opal stop codon. Asterisk denotes the stop codon. Arrowhead denotes the mutant base substitution. (b) Schematic depicting the conceptually translated 192-amino-acid product derived from the AB allele and the severely truncated 69-aa product derived from the boz^m168 allele. The gray-shaded box denotes the homeodomain and the black-shaded box denotes the GEH motif in the amino-terminal. (c) The molecular lesion in the boz^m168 allele generates a restriction fragment length polymorphism in which the single base-pair substitution TGG → TGA destroys an EaeI recognition site and generates a BspHI site. (d) nieuwkoid/dharma is linked to boz^m168, as shown by segregation of a BspHI restriction polymorphism in nieuwkoid/dharma sequences amplified from genomic DNAs from mapping crosses. A 1.1-kb PCR-amplified product from the nieuwkoid/dharma sequence is not cleaved by BspHI digestion in wild type. The boz^m168 mutant version is cleaved by BspHI digestion, reducing the fragment to 0.8 kb (arrow). Lane 1, homozygous wild-type G0 fish (*AB strain); lane 2, heterozygous ^m168 G0 fish; lane 3, size marker; lane 4, F2 homozygous wild-type sibs; lane 5, F2 phenotypically wild-type heterozygous sibs; lane 6, F2 mutant sibs (homozygous boz^m168). Arrow denotes the digested fragment generated by the BspHI site present in the boz^m168 but not in the *AB strain. The boz^m168 mutation segregates with this RFLP.