Figure 5.

Dose-dependent decrease in zebrafish iridophore pigmentation following the exposure to the mixture of 0.2 mM 1-phenyl-2-thiourea (PTU) and increasing concentrations of tariquidar (TQR) at 120 h post fertilization (hpf). A set of photographs showing lateral and dorsal views of 120 hpf zebrafish larvae exhibiting effects of 68 h PTU + TQR exposure on the iridophore pigmentation within the eye, dorsal head, and tail in four experimental groups: (a,a’,a”) exposed to PTU 0.2 mM, (b,b’,b”) exposed to PTU 0.2 mM + TQR 1 µM (c,c’,c”) exposed to PTU 0.2 mM + TQR 10 µM, and (d,d’,d”) exposed to PTU 0.2 mM + TQR 50 µM. PTU treatment resulted in melanophore disappearance with no influence on the iridophores (a,a’,a”; white arrows). Co-treatment with 1 µM TQR caused a slight reduction in the area covered with the iridophores; however, they were still well visible, mostly within the eye and tail (b,b”) (white arrows). In the 10-µM TQR co-treated group, only single iridophores were visible within the eye (c) (white arrow), while in the area of the dorsal head and tail they disappeared entirely (c’,c”). The addition of 50 µM TQR to the PTU solution resulted in a complete depletion of the iridophores within all areas investigated (d,d’,d”); however, small and faint melanophores were detectable (red arrows) (d’,d”). (e) A graph presenting the area covered by iridophores (µm²) measured at 120 h post fertilization (hpf) within the eye, dorsal head, and tail (Kruskall–Wallis, GraphPad Prism 5, *** p < 0.001, ** p < 0.01).