Fig. 2

Mature melanosomes are required for enrichment of inorganic elements in the RPE.

(A) Morpholino oligonucleotide (MO)-mediated knockdown of Tyrp1a/b results in the absence of mature melanosomes (brown colour of RPE) at 2 dpf, while control-MO injected embryos form mature melanosomes (black colour of RPE). (B) Distribution of inorganic elements in the eye of 2 dpf embryos injected with control (control-MOs, upper row) or tyrp1a/b-MOs (tyrp1a/b-MOs, lower row). The RPE enrichment of elements (arrow) seen in control-MO injected embryos is not observed in tyrp1a/b-MO injected embryos (n?=?3 for each group). Step size: 300?nm/pixel. (C) Images taken with high lateral resolution (100?nm/pixel) showing inorganic element enrichment in individual melanosomes in the RPE (arrow) of embryos injected with control-MOs (upper row). This enrichment is not evident or strongly reduced in tyrp1a/b-knockdown embryos (lower row). Colour scale: Ba 10.0?132.5?ppm; Br 0.1?6.5?ppm; Ca 0?1152?ppm; K 0?623.3?ppm; Mn 0.3?19.6?ppm; Pb 0.7?10.8?ppm; Se 0.3?4.6?ppm; Sr 0.3?19.6?ppm; Zn 0?152.9?ppm. Scale bars: (A,B) 50??m; (C) 5??m. (D) The content of each element in the RPE was shown as the ratio of tyrp1a/b morphants to control embryos, with all possible combinations between control MO-injected embryos (n?=?4 embryos) and tyrp1a/b MO-injected (n?=?5 embryos). Abundance of eight elements (Ba, Br, Ca, K, Mn, Se, Sr and Zn) showed significant reduction in the RPE after knockdown of tyrp1a/b (Mann?Whitney U test; U?=?0, *p?=?0.0158 for Ba, Ca, K, Mn, Sr and Zn; U?=?1, *p?=?0.0365 for Br; U?=?0, *p?=?0.0194 for Se).