Fig. 3

Pelvic fin loss in H. comes is associated with loss of tbx4.

a, Vista plot of conserved elements in the tbx2b-tbx4-brip1 syntenic region in fugu (reference genome), seahorse (H. comes), stickleback and zebrafish showing that tbx4 is missing from this locus in seahorse. The blue and red peaks represent conserved exonic and non-coding sequences, respectively. b, Lateral (top) and ventral view (bottom) of wild-type (WT) and a representative (one out of five) F3 homozygous tbx4-null mutant (tbx4^−/−) zebrafish. Bottom panel shows a close-up of the pelvic region (dashed lines indicate the approximate zoom region). Scale bar, 1 mm. Pelvic fins are indicated with black or white arrowheads in the wild-type fish. Homozygous tbx4-null mutants entirely lack pelvic fins without showing any other gross morphological defects.