Fig. 2

Expression of DrAlkals is sufficient for ectopic production of iridophores. (A) Schematic of ALKAL-expression constructs. Amp^R, ampicillin resistance; Tol2, medaka Tol2 transposase recognition sequence. (B) alkal expression in 72 hpf albino larvae. Weak alkal1 signal can be observed in the head, swim bladder (B1), notochord (B2; green arrowheads), and iridophores in dorsal and ventral stripes (B2; blue arrowheads). alkal2a mRNA is detected in the head (B3), swim bladder (B4), notochord (B5; green arrowheads), and iridophore stripes (B5; blue arrowheads). alkal2b mRNA is detected in swim bladder, a row of cells at the ventral aspect of the head (B7; white arrowhead), bilateral clusters in the head (B6; red arrowheads), behind the eyes (B6; black arrowheads), notochord (B8; green arrowheads), and iridophore stripes (B8; blue arrowheads). ltk expression is visible in swim bladder (B9), eyes (B10), notochord (green arrowheads), and iridophores (blue arrowheads). Negative controls, corresponding sense probes. (C) Supernumerary iridophores were observed in 5 dpf larvae upon ectopic expression of indicated DrAlkals in F₀-injected fish. ltk^mne larvae are used as positive controls. (D) Distribution of phenotypes of C. Fisher exact probability test showed significant differences (P < 0.001) in phenotype distribution in the following comparisons: any Alkal overexpressing fish against uninjected control and Akal2a overexpressing fish against Alkal1 or Alkal2b overexpressing fish. No significant difference was found between Alkal1 and Alkal2b overexpressing fish (P = 0.2). (E) Mosaic overexpression of alkal2a produces patches of supernumerary iridophores in adults.