Mating increases sensitivity of taste neurons through SPR.
(A) Scheme of the SEZ in vivo calcium imaging setup (top). Illustration of the SEZ area showing the innervation pattern of IR76b taste neuron axons (bottom). ROI 1 and ROI 2 delineate the regions of interest (ROI) used for quantification of the relative change in GCaMP-fluorescence (%ΔF/F). (B) Representative images of SEZ imaging of IR76b-Gal4; UAS-GCaMP6f mated and virgin female flies stimulated with distilled water (0 mM), 1 mM putrescine (1 mM), 10 mM putrescine (10 mM), and 100 mM putrescine (100 mM), respectively. (C) IR76b taste neuron terminals of mated females show a significantly increased response to putrescine after mating. While the response is highly significant at 1–6 h post-mating, it remains only a trend at 1 wk post-mating (n = 7). (D) Females at 1–6 h post-mating show higher IR76b taste neuron responses. GCaMP6f-fluorescence peak responses were quantified (in %ΔF/F) in the ROI 1 area. Flies were stimulated with increasing concentrations of putrescine (n = 7). (E) IR76b taste neurons of the same females as in (D) show no difference in the ROI 2 area. (F) Average response trace of the ROI 1 area (n = 7). The gray bar illustrates the stimulation period. The dark colored line in the middle presents the average value, and the light shade presents the SEM. (G) Representative images of IR76b GRN axons in the SEZ of test (IR76b-Gal4,UAS-SPRi;UAS-GCaMP5) and control (IR76b-Gal4;UAS-GCaMP5) females at 1–6 h post-mating. Flies were stimulated with distilled water (0 mM) and 10 mM putrescine (10 mM). (H) Quantification of peak responses (in %ΔF/F) of IR76b axon terminals of IR76b-Gal4,UAS-SPRi;UAS-GCaMP5 and control (IR76b-Gal4;UAS-GCaMP5) females at 1–6 h post-mating (n = 8). Box plots show median and upper/lower quartiles, and whiskers show minimum/maximum values. (I) Average response trace of ROI 1 and ROI 2 area of IR76b axons in the SEZ of IR76b>SPRi and control females (n = 8). All p-values were calculated using an unpaired t-test (*p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001).