Extended Data Figure 7: ser-4 expression in PHB is permissive for synaptic pruning.

(a) The normally hermaphrodite-specific PHB>AVA and PHA>AVG synaptic connections fail to prune in ser-4 mutant males, but can be rescued by cell-specific expression of ser-4 cDNA in PHB or PHA. Top panel shows red cytoplasmic axon label, middle panel shows GRASP (PHB>AVA) or iBLINC signal (PHA>AVG), bottom panel shows magnified inset of color-inverted synaptic puncta with arrowheads to indicate puncta. Scale bars, 10μm, all panels. Representative images shown, for quantification and replication see Fig. 4c and Methods.

(b) ser-4 smFISH puncta are present in PHB in both sexes at L1. Three consecutive individual z-slices taken from the maximum intensity projections in Fig. 4b are shown, moving laterally through each animal from top to bottom rows. Dotted circles outline the PHB nuclei (DAPI) identified using osm-6::gfp (see Fig. 4b). Arrowheads in the top row indicate the location of ser-4 puncta, which fade out of focus as the slices progress laterally. For quantification and replication see Fig. 4b and Methods.