Skip to main content
. 2017 Sep 13;6:e29257. doi: 10.7554/eLife.29257

Figure 1. Cell adhesion protein genes casy-1 and rig-6 are required for axon fasciculation.

(A) Schematic of the position of cell bodies and axons of three neurons HOA (red), AVG (blue) and a pair of PHC (green) in the male (ventral view). The dashed box indicates the axons and HOA synaptic output analyzed in (C and D) and imaged in (F and H). (B) Electron micrograph showing the axons and synapses of HOA, PHC and AVG. Arrowheads indicate presynaptic density of dyadic synapses of HOA and PHC. Asterisk indicates a mitochondrion. In the schematic, axons are colored as in (A), and presynaptic density is indicated as gray. (C) The number of electron micrograph sections for axon-axon contact between neuron pairs. N2Y series were analyzed from section #13906 to #14249, except for the PHC-AVG (from #13836 to #14249) (WormWiring: http://wormwiring.org). See also Supplementary file 1. (D) Synaptic output of HOA and the connectivity of HOA, AVG and PHC in the boxed region shown in (A). (HOA makes additional connections outside this region.) Synaptic weight determined by electron micrograph section numbers is indicated. The number of sections that contain dyadic synapses (HOA > AVG,PHC or PHC > HOA,AVG) is indicated in parenthesis. (E) Expression of transcriptional reporters for neural cell adhesion genes in the three neurons. One hundred out of 106 neural cell adhesion genes (94%) have been examined and the genes having expression in the three neurons are shown. (F) Distribution of a mCherry-tagged presynaptic marker RAB-3 in HOA axon of wild type or indicated mutants. Arrowheads indicate gaps between the presynaptic puncta. (G) Number of mCherry::RAB-3 puncta in mutants was counted and compared to wild type (n = 30). Error bars are SEM. (H) HOA presynaptic puncta (mCherry::RAB-3; red) were simultaneously visualized with GFP-labeled HOA and AVG axons (green) in wild type, or casy-1 or rig-6 mutant animals. Arrowheads indicate the gap region containing smaller or fewer presynaptic puncta. (I) Percentage of axon-axon contact between HOA and AVG in wild type or mutant animals (n = 40). Each dot represents individual animal. Red bar represents the median. (J and K) The mCherry::RAB-3 puncta size (J) or number (K) was measured and compared in the contacting and non-contacting axonal segments between HOA and AVG for the indicated genotypes. The number of the puncta (J) or of axon segments (K) analyzed is indicated below each column. Error bars are SEM. Scale bars, 20 μm. *p<0.05; **p<0.01; ***p<0.001 (by Mann-Whitney test). For the data and statistics, see Figure 1—source data 1.

Figure 1—source data 1. Source data for Figure 1, Figure 1—figure supplement 1, and Figure 1—figure supplement 2.
elife-29257-fig1-data1.xlsx (27.2KB, xlsx)
DOI: 10.7554/eLife.29257.006

Figure 1.

Figure 1—figure supplement 1. Visualizing HOA presynapses.

Figure 1—figure supplement 1.

(A) Lateral and ventral views of the tail region of animals carrying eat-4pA::gfp (green) and eat-4pA::mcherry::RAB-3 (red). The eat-4pA is a fragment of eat-4 promoter and drives expression only in HOA and PCA in the male tail. (B) Images of mosaic expression in HOA or PCA in transgenic animals used in (A). HOA, but not PCA, has an anteriorly-oriented projection with discrete RAB-3 puncta. Scale bars, 20 μm.
Figure 1—figure supplement 2. Extra branching of HOA in sax-3(ky123) mutants.

Figure 1—figure supplement 2.

(A) HOA axon of wild type or sax-3(ky123) mutants. Arrowheads indicate extra branches of HOA. Scale bar, 20 μm. Percentage of animals with extra branches of HOA was measured and compared to wild type (n = 50). ***p<0.001 (by Fisher’s exact test). For the data and statistics, see Figure 1—source data 1.
Figure 1—figure supplement 3. Phenotypes of rig-6(gk438569) mutants.

Figure 1—figure supplement 3.

(A) Distribution of a mCherry-tagged presynaptic marker RAB-3 in HOA axon of rig-6(gk438569) mutants. Arrowheads indicate gaps between the presynaptic puncta. Scale bar, 20 μm. (B) Number of mCherry::RAB-3 puncta in mutants was counted and compared to wild type (n = 30). Error bars are SEM. The data for wild type and rig-6(ok1589) mutants are identical to those in Figure 1 and are shown for comparison. **p<0.01; ns, not significant (by Mann-Whitney test). For the data and statistics, see Figure 1—source data 1.