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Fig. 4
Simultaneous imaging of pre- and post-synaptic compartments of retinotectal synapses. (a) First image of a time-lapse series showing the Psd95-DsRedEx labelled post-synaptic sites on the dendritic arbor of a tectal neuron (red) and the Sypb-EGFP labelled pre-synaptic terminals on the axonal arbor of multiple RGCs (green) in a 4-dpf PGUSG larva with transient expression of elavl3:psd95-DsRedEx. The nasal is upwards. Scale bar, 20 μm. (b) Enlarged view of the boxed region in. (a) Scale bar, 5 μm. (c) Enlarged view of the boxed region in (b) showing single-channel images and the composite image. The yellow arrowhead (bottom) indicates the association of a pre-synaptic terminal labelled by Sypb-EGFP (green, top) with a post-synaptic site labelled by Psd95-DsRedEx (red, middle). (d) Single optical section of the boxed region in (c) showing the fluorescence overlap of the pre- and post-synaptic punctum. (c,e–j) 2-h time series with a 20-min interval showing the overlap of pre- and post-synaptic labels (yellow arrowheads) is stably maintained. Time in minutes is indicated at the bottom right corner of each panel. Postsynaptic Psd95-DsRedEx puncta also showed dynamic behaviours: elimination (blue arrow), transient (magenta arrow), and formation (cyan arrow). Scale bar, 5 μm.