The Dolutegravir solubility dmso timing of CO2-evoked Ca2+ responses in both AFD and BAG correlated with peaks in locomotory activity (Figure 6A). We investigated these correlations directly by ablating AFD and/or BAG and examining behavioral responses (Figure 6B). For statistical comparison, we chose time intervals before and after gas switches according to the occurrence of peaks in wild-type behavioral rates. In the absence of food, neither AFD nor BAG ablation abolished modulation of speed across shifts in CO2 (Figures 6B and S4). Stronger phenotypes were observed for reversal and omega rates (Figure 6B). Unexpectedly, ablation of AFD increased reversal and omega rates following

a sharp CO2 rise (ttx-1, Figures 6B, 7B, 7C, 7H, and 7I) and reduced suppression of omega turns following a CO2 fall (ttx-1, Figures 6B, 7K, and 7L), suggesting that AFD acts to suppress reversals and omega turns at these two time points. Ablation of BAG abolished reversal and omega responses to a rise in CO2 (pBAG::egl-1, Figures 6B, 7B, 7C, 7H, and 7I) and reduced the suppression of omega turns following a CO2 fall (pBAG::egl-1, Figures 6B, 7K, and 7L), consistent with BAG excitation promoting reversals and omega turns. Coablation of AFD and BAG abolished the suppression of reversals and omega turns following a

fall in CO2 (ttx-1; pBAG::egl-1, Figures 7F and 7L). This effect was due to reduced reversal and omega rates under prolonged high CO2 (ttx-1; pBAG::egl-1, Rucaparib clinical trial red bars, Figures 7E and 7K). These data suggest that together BAG and AFD act to suppress reversals and omega turns when CO2 decreases. Curiously, AFD-ablated BAG-ablated animals continued to show a transient increase in reversals following a CO2 rise (ttx-1; pBAG::egl-1, Figures 6B, 7B, and 7C). This result suggests that there is at least one other CO2 “ON” sensory neuron, XYZ, that promotes reversals in response to a CO2 rise. It also suggests that after a CO2 rise, AFD acts antagonistically to both BAG and the hypothetical XYZ neuron to inhibit reversals. We

investigated whether the ASE or AQR, PQR, URX neurons could be XYZ by ablating them together with AFD and BAG. Ablating ASEL/R had no significant effect on unless the reversal rate of AFD-ablated BAG-ablated animals immediately following a CO2 rise (che-1; ttx-1; pBAG::egl-1, Figures S5A–S5D) but did alter reversal rates under prolonged high CO2 ( Figures S5E and S5F). The ablation of AQR, PQR, URX by an integrated pgcy-36::egl-1 transgene caused an increase in the reversal rate of AFD-ablated BAG-ablated animals in air alone ( Figures S5A–S5D). These data suggest that the ASE neurons suppress reversals under prolonged high CO2 and that the AQR, PQR, URX neurons suppress reversals in the absence of CO2. However, even animals defective in AFD, BAG, ASE, AQR, PQR, and URX retained some CO2 responsiveness, suggesting that C. elegans has additional CO2 sensors. Wild-type C.