Fig. 3

Figure 3. SNRNP70 is cell-autonomously required in motor neurons for neuromuscular assembly

(A) A representative image showing transplanted sibling motor neurons derived from a Tg(mnx1:GFP) line innervating a WT host myotome that has been stained with anti-SV2 and α-BTX to mark pre- and post-synaptic sites, respectively. Bottom: inset depicting the apposition (red arrows) of pre- (within the GFP⁺ motor neurons) and post-synaptic sites within a small region of the myotome. Scale bars, 25 μm.

(B and C) Examples of transplanted GFP⁺ null motor neurons innervating WT host myotomes that have been stained with anti-SV2 and α-BTX. In (B), null GFP⁺ motor axons terminate in a motor-axon-sparse region of the myotome, whereas in (C), they terminate in a motor-axon-dense region. Bottom: insets depicting the apposition (red arrows) of pre- (within the GFP⁺ motor neurons) and post-synaptic sites regions of the myotome. Cyan arrows indicate the absence of host AChR clusters adjacent to transplanted GFP⁺/SV2⁺ terminals. Scale bars, 25 μm.

(D) Quantification of the degree of overlap between SV2 and α-BTX in the three groups of transplanted motor axons. The graph shows mean values ± SEM. ^∗∗∗p< 0.001, one-way ANOVA, n = 6 donor/host pairs for sib-to-WT group, n = 3 donor/host pairs for null-to-WT group in three independent experiments.

See also Figure S3.