Fig. 3

Nasal and Trigeminal Ablation Diminishes CO2-Evoked Avoidance Behavior (A–C) Dorsal (A and B) and lateral (C) fluorescence views of Tg(Huc:Gal4;UAS:GCaMP5) zebrafish larvae before (left) and after (right) nasal (A), OB (B), and trigeminal ganglion (gV) (C) ablation. Dotted lines mark the locations of the nose (A), OB (B), and trigeminal ganglion (C), in which GCaMP5 fluorescence is no longer apparent after the ablations. Scale bars, 100 μm. (D and E) Effects of nasal, OB, and trigeminal ganglion ablations on CO2-evoked Ca2+ responses. (D) Dorsal views of intact, nasal-, OB-, and trigeminal ganglion-ablated Tg(Huc:Gal4;UAS:GCaMP5) zebrafish larvae. Scale bar, 100 μm. (E) Bar graphs showing the maximal ΔF/F evoked by CO2 in various brain regions in intact (red, n = 6), nasal-ablated (orange, n = 6), OB-ablated (purple, n = 6), and trigeminal ganglion-ablated (green, n = 5) zebrafish. Values represent mean ± SEM. (F and G) CO2-evoked avoidance response in intact (red, n = 24), nasal-ablated (orange, n = 9), OB-ablated (purple, n = 11), and trigeminal ganglion-ablated (green, n = 10) zebrafish. A high concentration of CO2 (700–780 mg/L) was used in this experiment. (F) Avoidance latencies after the CO2 stimulation onset. Wilcoxon signed-rank sum test for comparisons between intact and ablated fish. ∗∗∗p < 0.001. (G) Avoidance probability upon application of CO2. Open, light-shaded, and dark-shaded bars represent the percentages of fish that showed avoidance responses within 5, 10, and 15 s after the stimulus onset, respectively. See also Figure S3.