Extended Data Fig. 1: C. elegans neurons have hallmarks of an AIS.
From: Endocytosis in the axon initial segment maintains neuronal polarity
(a) Schematic of flippase-mediated GFP-tagging of proteins for cell-specific endogenous labeling. (b) Cell-specific endogenous expression of the medium isoform of ankyrin/UNC-44 (UNC-44M-FLPon-GFP) in the PVD neuron. (c) Average fluorescence intensity in each neuronal domain. (d) Cell-specific endogenous expression of UNC-44M-FLPon-GFP in the DA9 neuron. (e) Schematic of DA9 neuronal domains. (f) Kymograph analysis of endogenous DMA-1-GFP vesicular trafficking. (g) Quantification of DMA-1-GFP vesicular trafficking (n = 70 vesicles/region from 13 (dendrite) or 26 (AIS) animals over 6 experiments). (h) Confocal microscopy images of mCD8-GFP after fluorescence recovery after photobleaching (FRAP). Black squares indicate zoomed regions. (i) Fluorescence intensity of the red region in h. FRAP recovery kinetics are sensitive to neurite geometry, which may affect recovery rates. P < 0.0001 using a two-way ANOVA. (j) Schematic of the receptor complex mediating PVD dendrite branching. (k) Axonal branches in the 50 microns distal to the AIS. (l) Endogenous DMA-1-FLPon-GFP localization in the axon of the indicated genotypes. (m) DMA-1-FLPon-GFP polarity index of animals described in l. (n) Axonal region of animals of the indicated genotype. (o) Axonal branches in the 50 microns distal to the AIS. (p) Endogenous DMA-1-FLPon-GFP localization in the axon of the indicated genotypes. (q) DMA-1-FLPon-GFP polarity index of animals described in p. Data are shown as mean ± s.e.m. N-values are indicated on bar graphs and represent the number of animals. P values in c and q were calculated using a one-way ANOVA with Dunnett’s. P values in g were calculated with a mixed model ANOVA with Šidák multiple comparison test. P values in m were calculated using an unpaired two tailed t test with Welch’s correction. Scale bars, 10 µm (d), 5 µm (b, h top, n), and 2 µm (f, h bottom, l, p).
