Fig. 4

mSod1 embryos and larvae show defects in the clustering of synaptic vesicles and the maturation of neuromuscular junctions.

(A) Confocal analysis of the 9–13^th somite trunk region at 48 hpf. Scale bar: 25 μm. (B) There were no differences among the control (Ctrl), wtSod1 and mSod1 embryos and larvae in terms of motor axon length (respectively 147.2 ± 5.2 μm, 139.3 ± 4.6 μm, and 135.1 ± 5.5 μm), the number of branches (18.1 ± 2.5, 19.7 ± 2.1, and 22.1 ± 1.8), or unbranched axon length (28.9 ± 4.8 μm, 6.6 ± 2.1 μm, and 7.9 ± 2.2 μm) (data not shown). The measurements were made in at least four motor nerves of a minimum of 10 embryos for each genotype. Three-dimensional (3D) object-based co-localization analysis (numerical data given in Table 1) did not reveal any differences in the densities of total pre-synaptic or pre-synaptic co-localizing clusters, or in the densities of total post-synaptic or post-synaptic co-localizing clusters, but there was a significant increase in the area of pre-synaptic (but not post-synaptic) clusters in the mSod1 embryos. (C) Confocal analysis of the 10–15^th somite trunk region at 96 hpf. Scale bar: 25 μm. (D) Although the mean area of the pre- and post-synaptic clusters in the different genotypes remained unchanged, 3D object-based co-localisation analysis showed a significant reduction in the density of presynaptic (but not post-synaptic) SV2A clusters in mSod1 NMJs, and a significant reduction in co-localizing pre- and post-synaptic clusters in mSod1 larvae (numerical data given in Table 1).