Fig 1

Fig 1 Triple homozygous hox13 mutants have severe defects in ray patterning in all fins except the caudal fin.

A) Schematic representation of CRISPR-Cas9 induced deletions in hoxa13a, hoxa13b, and hoxd13a. Portions of the genes deleted in the mutants are shown within the red box. Translation start and stop sites are represented as ATG and Stop respectively. Locations of genotyping primers are indicated as black arrows as either F (forward) or R (reverse). Homeobox sequence locations are represented as HB. The black boxes represent exons, and the white boxes represent untranslated region. B) Caudal, dorsal, anal, and paired fins of wildtype siblings (n = 6) and triple homozygous hox13 mutant fish (n = 10). Phenotypes were consistent with the exception of n = 3/10 anal fins in the triple hox13 mutant, which show irregular joint spacing in the anal fin (S1C Fig). Yellow arrowheads show examples of bifurcation, and white arrowheads show examples of joints present in all fins of wildtype fish as well as in the caudal fin of triple hox13 mutants but absent in the pectoral, pelvic, dorsal and most of the anal fins of the triple hox13 mutants. Scale bars, 2mm for caudal and anal fins, 1.5mm for dorsal fins, 1mm for pectoral fins, 0.5mm for pelvic fins. (C-D) Enlarged images of triple hox13 mutant and wildtype sibling caudal fin rays corresponding to the boxed area shown in B. Joints are regularly spaced in rays of wildtype fish (C). White arrowheads indicate joints and yellow arrowheads indicate bifurcations. The red arrowhead in D indicates a long bone segment with abnormal joint spacing in the mutant. Scale bars, 100 µm. (E-F) Enlarged images of the triple hox13 mutant and wildtype sibling fin ray tips are presented to demonstrate the lack of actinotrichia fibers at the tips of the mutant rays. Scale bars, 100 µm.