Figure 4

SAD-1 kinase is required during the establishment of neuronal polarity but largely dispensable for the maintenance of neuronal polarity and synaptic organization. (A) Development of the GABAergic motoneurons. DD neurons arise embryonically and form synapses in late L1. VD neurons arise concomitantly. Whereas the establishment of DD and VD neurons is mostly complete by the end of L2, they are maintained for the C. elegans lifetime. (B) Two early larval and one late exposure. SAD-1as animals were exposed to 1NA-PP1 throughout establishment (Bi), partially during establishment (Bii), or during maintenance (Biii) (filled bars) and observed at an adult stage (solid line). (C) Polarity phenotypes following the exposures. The three-day establishment exposure abolished the rescuing effects of SAD-1as, and the 30-hour duration was sufficient to replicate this full establishment exposure. The 41-hour exposure had no effect. N.S., not significant, Wilcoxon rank-sum test. Error bars indicate standard deviations. (D) Synaptic organization phenotypes following the exposures. Animals treated with 1NA-PP1 throughout establishment for three days occasionally displayed diffuse juIs1 puncta (bottom panel) compared to DMSO-treated animals (upper panel) (Di). The 30-hour and 41-hour durations had no effect on the SAD-1as-induced rescue (Dii-iii). Quantification and density estimates of the punctum widths show that there is no obvious difference between DMSO (black) and 1NA-PP1 (red) treatments for any of the three exposures (Div-vi). All density graphs show punctum widths on the x-axis and density on the y-axis. Scale bar, 5 μm.