Fig. 9

Melanosome biogenesis is mildly disrupted by loss of PIKfyve. A) 48 hpf zebrafish embryos exposed to 500 nM apilimod during melanosome biogenesis (22 to 48 hpf) exhibit a variable reduction, but not total loss, of body and eye pigment. PTU-treated fish is used as a negative control, exhibiting a nearly complete loss of pigment at this stage. B) Melanin quantification by fluorescent spectroscopy showed a significant reduction in pigment in the embryos treated with apilimod from 22 to 56 hpf compared to fish raised in EM or 1% DMSO in EM, but significantly more pigment than PTU-treated fish. Each dot represents a sample generated from a group of 56 embryos. C) TEM images of 6 dpf control uninjected and pikfyve crispant larval zebrafish reveal the presence of fragmented melanosomes and fewer mature rod-shaped melanosomes upon PIKfyve loss. D-E) Quantification of melanosomes in TEM images showing no change in the number of melanosomes per 10 μm length of RPE, but a significant increase in circularity. Dots in D and E represent average measurements from individual fish, n = 3 fish per condition. ∗p < 0.05.