Figure 2: The involvement of the chdA gene in the twin-tail phenotype.

(a) Lateral view of wild-type (Wt) and twin-tail (Twin) goldfish larvae. The lower panels are magnified views of the larval caudal regions. Blood cell accumulation and duplicated fin folds are indicated by the black arrow and arrowhead, respectively. (b) The goldfish chdA^wt and chdA^E127X amino-acid sequences. The positions of CR domains are indicated by grey boxes. The twin-tail-specific mutation changes a glutamic acid codon (GAG) to a stop codon (TAG) at amino-acid position 127 (the mutated nucleotide is indicated by the red ‘T’). A twin-tail-specific AvaI site is located near the stop codon (indicated by the blue line and ‘G’). (c) Dorsal views of the Wt and eight twin-tail goldfish strains. (d) Schematic detailing the phenotyping of backcross segregants. Scale bars, 1 mm (upper row in a), 0.1 mm (bottom row in a), approximately 1 cm (c).