Fig. 3

Fig. 3

a Schematic representation of Pisces expression in the habenula, locus coeruleus (LC), and the whole brain of 3 or 6-dpf larval zebrafish. Single pulses of a 405-nm laser (0.5 μW for 60 s or 1.5 μW for 10 s) were used for activation. b Time-lapse imaging demonstrates the rapid axonal trafficking of Pisces in tectal neurons following 405-nm laser activation (1.5 μW for 10 s) on 6-dpf larval zebrafish. White arrowheads show the axonal progression of Pisces labeling, while blue arrowheads mark the activated neuron nucleus. Pisces labels the entire axon within 2 min, and all processes are labeled within 30 min. The estimated axon trafficking rate is 1.02 ± 0.06 μm/s based on 14 neurons. The morphological trace of an activated neuron is shown on the right. Scale bars: 10 μm. Larvae were raised in constant darkness. Representative z-axis maximum projection images of the morphological projections of two activated habenula neurons on both sides (c) and one LC-NE neuron (d) on 6-dpf larval zebrafish. The brightness of red fluorescence was adjusted to visualize the nuclei of activated neurons in the lower panels. Numbers and white arrowheads indicate the activated neurons. Morphological traces of each neuron are displayed on the right (n = 3 fish). Scale bars: 50 μm in whole images, 10 μm in zoomed views. Hb habenula, IPN interpeduncular nucleus. Larvae were raised in constant darkness. e Fluorescent images showing tectal neuron morphology (left, at 2 h post-activation), and neurites and filopodia (right) dynamics of a tectal neuron in a 3-dpf zebrafish over 14 h. White arrowheads indicate neurite changes. Laser activation was performed with 405-nm (0.5 μW for 60 s) (n = 6 fish). Scale bars: 10 μm. Raw images and traces can be found in Supplementary Fig. 4c. Larvae were raised in ALE. See also Supplementary Figs. 3–5 and Supplementary Movies 2–6.