Fig. 4

slc25a25b is required for left–right organ patterning in zebrafish.

(A,B) As a measure for left–right asymmetry, heart looping of slc25a25b-morphant fish was visualized by in situ hybridization for cmlc2. (C) Knockdown of slc25a25b caused randomization of heart looping (slc25a25b^MO; *P = 1.1 × 10⁻³⁴). This phenotype was rescued by injection (+) of slc25a25b mRNA in a concentration-dependent fashion (+slc25a25b). (D-F) southpaw (nodal) expression in 15-somite stage slc25a25b-morphant zebrafish embryos was visualized by in situ hybridization. (G) In contrast to control fish, in which southpaw expression was largely restricted to the left side, slc25a25b-morphant fish showed randomized southpaw expression (*P = 0.00008). Numbers of embryos are indicated above bars. L = left; S = symmetric; R = right. This denomination for heart looping is equivalent to wt d-loop, symmetric no-loop, and reversed, sinistral s-loop [33]. For numerical values, see S1 Data. cmlc2, cardiac myosin light chain 2; hpf, hours post fertilization; wt, wild type.