Figure 4.

Loss of swip-10 results in elevated vesicular release in DA terminals and DA-dependent reductions in crawling speed. A, Schematic illustration of the experimental transgenes used in B. The pH-sensitive GFP fluorophore pHlourin fused in frame to the C terminus of the synaptic vesicle protein SNB-1 was expressed solely in DA neurons via the asic-1 promoter as in Voglis and Tavernarakis (2008). Vesicular fusion rates at DA neuron synapses was then monitored using FRAP. Images illustrate a wild-type PDE neuron synapse before bleaching and during different points of recovery. B, Loss of swip-10 results in a significantly elevated rate of fluorescence recovery, indicative of a more rapid vesicular fusion rate. Data were fit to a one phase exponential using nonlinear regression. K (rate constant) = 0.032 ± 0.002 s⁻¹ for N2 vs 0.063 ± 0.01 s⁻¹. p < 0.05, Student's two-tailed t test. Red arrow denotes the time point immediately after photobleaching. Confocal images and FRAP were performed as described in the Materials and Methods. C, Loss of swip-10 results in a DA-dependent decrease in crawling on solid substrate. Crawling videos and tracking were performed using WormLab as described in the Materials and Methods. Data were analyzed using one-way ANOVA with multiple Tukey posttests. Unlike dat-1, swip-10(vt29) demonstrates a significantly reduced speed relative to N2 that is fully restored by loss of cat-2. ***p < 0.001.