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. 2020 Jan 3;9:e50065. doi: 10.7554/eLife.50065

Figure 1. An extensive collection of terminal identity markers for distinct motor neuron subtypes of the C.

elegans ventral nerve cord. (A) Schematic showing distinct morphology for each motor neuron subtype in the C. elegans hermaphrodite. Below, colored dots represent the invariant cell body position of all MNs of the ventral nerve cord (VNC). Red: 39 sex-shared cholinergic MNs (DA2−7 = 6 neurons, DB3−7 = 5, VA2−11 = 10, VB3−11 = 9, AS2−10 = 9); Green: six hermaphrodite-specific VC MNs; Yellow: four sex-shared GABAergic DD neurons (DD2−5 = 4); Blue: nine sex-shared GABAergic VD neurons (VD3−11 = 9). With the exception of VC, all other subtypes have 1–3 extra neurons located at the flanking ganglia (retrovesicular and pre-anal) of the VNC (not shown). Individual neurons of each subtype intermingle along the VNC. (B) Table summarizing expression of terminal identity markers for VNC MNs. The sex-shared GABAergic MNs (DD, VD) and the sex-specific MNs (VC, CA) do not express UNC-3. Conversely, the sex-shared cholinergic MNs (DA, DB, VA, VB, AS) and the sex-specific MNs (VC, CA) do not express UNC-30/Pitx. For the genes indicated with an asterisk (*), a detailed expression pattern is provided in Figure 1—figure supplement 1. Of note, the male-specific MNs of the CP subtype are also not shown. (C) Schematic that summarizes the known function of UNC-3 (activator of cholinergic MN identity genes) and the question under investigation: does UNC-3 prevent expression of terminal identity features reserved for other MN subtypes?.

Figure 1.

Figure 1—figure supplement 1. Detailed characterization of the expression pattern of VC and VD terminal identity markers.

Figure 1—figure supplement 1.

(A) An expression map of VC and VD terminal identity genes with single-cell resolution at larval stage 4 (L4). Each column represents an individual motor neuron (MN) in the ventral nerve cord (VNC) of a hermaphrodite worm. MN subtypes are color-coded. This table represents a summary of the co-localization analysis described in panel B. Apart from the seven genes listed, we also examined five additional terminal identity genes (bra-1, dhc-1, rgs-4, vhp-1, vps-25) but found no evidence for expression in VD or VC neurons. (B) Co-localization analysis of VD and VC terminal identity genes. Each column represents an individual MN in the VNC of a hermaphrodite worm. Each row represents a randomly-selected worm co-expressing the respective VD or VC marker and one of the known identity markers: unc-47::mChOpti or unc-25::gfp for GABAergic (VD and DD) MN identity, cho-1::rfp or unc-17::gfp for cholinergic MN identity and lin-11::mCherry or ida-1::gfp for VC MN identity. A color-filled lattice indicates co-expression of the known identity marker and the selected marker in the individual MN.