Figure 7.

FlincG3 allows visualization of cGMP production in PHB chemosensory neurons in response to the repellent SDS. (A) Diagram of the PHB circuit; this figure is reproduced from Figure 1C in Varshney et al. (2018) under the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/). The primary postsynaptic partners of PHB neurons are the AVA backward command interneurons and the PVC forward command interneurons (Hilliard et al. 2002; Park et al. 2011; Tran et al. 2017). (B) Diagram of the sodium dodecyl sulfate (SDS) behavioral assay, which tests the PHB circuit response to 1 mM SDS; this figure is reproduced from Figure 1D in Varshney et al. (2018) under the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/). Animals are induced to move backward with a nose touch from a hair pick (Hilliard et al. 2002; Park et al. 2011; Tran et al. 2017). A drop of 1 mM SDS is placed behind them on a dry NGM plate, so that the drop quickly absorbs into the media, preventing wicking along the worm. The time that the animal backs into the drop before stopping is measured. (C) FlincG3 expression in PHB does not affect the response of animals to SDS (P ns). For reference, loss of tax-4 causes a severe defect in the ability to sense SDS (Hilliard et al. 2002). One-factor ANOVA analysis was first performed, then two-sample t-tests and the Hochberg procedure for multiple comparisons were performed. (D) When FlincG3 is expressed in PHB neurons, ΔF/F₀ (%) increases steadily after introduction of 1 mM SDS. Average fluorescence response (ΔF/F₀ (%)) of FlincG3 in the PHB cell body shown as bolded traces responding to either 1 mM SDS presentation or M13 buffer alone (represented at the bottom of the panel). Thinner traces are from individual recordings for each condition. n = 15 for animals exposed to M13 control buffer, then switched to another channel with M13 control buffer, and n = 27 for animals exposed to M13 control buffer, then switched to another channel with 1 mM SDS in M13 buffer. (E) The areas under the curve for recordings before and after SDS presentation are different (permutation test, P < 0.01). The areas under the curve for M13-only recordings are not different (permutation test, P ns). Horizontal bars indicate mean; vertical error bars indicate ± SD. See Materials and Methods for details of statistical analysis.