Figure 3
An automated C. elegans solvent screen yields suppressors of optogenetically-activated neural responses. (a) Multiwell plate map showing 57 wells containing solvents at 1% and 5% concentrations alternating with control S. Basal buffer (gray fill). Diagram below shows the optical path for simultaneous stimulation and monitoring of neural responses, via 470 nm blue excitation of GCaMP and green emission, and 617 nm red light stimulation of the Chrimson ion channel. (b) Wide-field 4X fluorescence image of young adult animals co-expressing GCaMP and Chrimson in the AWA sensory neurons in each animal (arrows) within a reversibly-sealed single-arena microfluidic device. (c) A schematic of excitation and emission wavelengths used for simultaneous optogenetic stimulation of AWA sensory neurons using Chrimson and recording of intracellular calcium levels with GCaMP. (d) A heat map representing 1,140 peak normalized neural responses (∆F/F0) across 20 individual animals and 57 solutions. Horizontal blue box highlights animal #8, identified in panel b. (e) Box plot shows population average peak ∆F/F0 neural activation response for each compound. Symbols represent statistically significant mean peak differences compared to immediate prior controls (*p < 0.001, ANOVA repeated measures with Bonferroni correction). Boxes indicate 25th and 75th percentiles, whiskers extend to 1.5 times the interquartile range, and outliers are indicated with diamond symbols. (f) Bar graphs show the difference in mean peak ∆F/F0 response between each solvent concentration and its immediate prior buffer control. Error bars represent SD. Symbols represent statistically significant relative mean peak differences (*p < 0.001, paired one-sample t-tests with Bonferroni correction). (g) Example neural traces show suppression of optogenetic stimulation by isopropanol. Population average animal ∆F/F0 calcium responses (black line) to 5 s of red light stimulation are shown for wells 9 to 13 (outlined in d). Shading represents SD. Blue lines indicate responses from animal #8.
