Fig. 5

a Experimental design of single-cell RNA-sequencing experiment. b Two-dimensional UMAP representation of the collected skin cell clusters (dashed ellipse marks iridophores). c Anatomical origin (stripe versus interstripe) of iridophores from clusters 5 (blue) and 3 (yellow). d A volcano representation of differentially expressed genes between clusters 5 (blue) and 3 (yellow), where 192 genes were upregulated in cluster 5 and 158 were upregulated in cluster 3. e, f The response of an adult zebrafish skin pattern to norepinephrine (NE) stimulation. e The optical response of individual iridophores from the stripe (upper panel) and interstripe (lower panel). In the stripe, the reflection peak of an ordered iridophore shifts from ~450 to ~570 nm upon NE treatment. In the interstripe, only minor changes in the reflection spectra occur in response to NE. n = 4 different fish (f) illustrates optical response from relaxed, untreated fish (−NE) to the treated fish (+NE). Note the differences between the blue stripe and the two-flanking yellow interstripes and how this changed with NE treatment. Before treatment, a deep blue color for the stripe region and a golden-yellow color for the interstripe region is observed. After NE treatment, the contrast between the stripe and the interstripe is drastically reduced. This color change arises because NE causes pigment granules within the melanophores in the stripe to aggregate in the cell center and blue iridophore reflectance to shift from a dark-blue to green-yellow hue (see upper insets), while in the interstripe, NE causes the pigment granules within the xanthophores to aggregate and silvery iridophores to have only a minor color change (lower insets), n = 3 different fish. Scale bar, f 400 μm.