Fig. 4

Impdh1a localization in photoreceptors is dynamic.A, representative IHC images of zebrafish outer retina at 11 AM and 11 PM stained with antibodies against Impdh1a (top white and bottom green) and colabeled (bottom panels) with transgenic cone-targeted GFP (blue) and rods (4C12, magenta). B, detailed IHC images of photoreceptor inner segments throughout the day. Impdh1a (green) counterstained with cone or rod markers (magenta). C, cumulative frequency distributions of particle circularity ratios in rods and cones throughout the day. N = 4 animals, three experiments each. D, comparison of particle circularity ratios in cones and rods at 5 PM. E, detailed IHC images of photoreceptor synapses at 11 AM and 11 PM. Top, Impdh1a (green) counterstained with cone (blue) or rod (magenta) markers. Middle and bottom, Impdh1a signal overlapping with cone or rod synapse masks, respectively. F, quantification of mean synapse fluorescence in cones and rods at 11 AM and 11 PM, normalized to 11 PM. Each symbol is a different animal, three experiments for each animal. G, hypothesized model for Impdh1a dynamics throughout the day. In daytime, longer Impdh1a filaments occupy the inner segments, surrounding mitochondrial clusters (M) and nuclei (N). More subtle changes occur at synapses, with slightly reduced Impdh1a immunoreactivity at night. IHC, immunohistochemistry; impdh, inosine monophosphate dehydrogenase.