Figure 1. RMG activation induces rapid and persistent forward movement.
(A and B) URX O2 sensors provide an entry point to the circuit controlling response to 21% O2. Selective expression of GCY-35 in URX neurons restores rapid (A) and persistent (B) forward movement at 21% O2 to gcy-35; npr-1 animals on food. Statistics compare rescued (blue) and mutant (red) animals at time points indicated by the black bars. (C) 21% O2 causes npr-1 animals on food to suppress the short, frequent reversals observed at 7% O2. Reversal probability is calculated per 1 s. (D) Ablating URX abolishes the Ca2+ responses evoked in RMG by 21% O2; unc-64 syntaxin loss-of-function mutants show a partial reduction in this response. Here, and in subsequent panels, black bars indicate time intervals for statistical comparison of responses at 21% and 7% O2 using the Mann–Whitney U test. ***p<0.001; **p<0.01; *p<0.05; NS, not significant. (E and F) Stimulating RMG using channelrhodopsin evokes rapid movement (E) and inhibits backward movement (F) in npr-1 animals kept at either 7% or 21% O2 with food. Here and in subsequent panels, red bars indicate time intervals used for statistical comparisons of responses when light is on to when it is off. ***p<0.001, **p<0.01; *p<0.05; NS, not significant. (G–I) Channelrhodopsin stimulation of RMG can induce rapid movement when AQR, PQR, and URX neurons are ablated. Data plotted in (I) are replotted from G and H. (J) URX Ca2+ responses evoked by 21% O2 are strongly attenuated when RMG is ablated. (K) URX neurons retain O2-evoked Ca2+ responses in unc-64 syntaxin mutants, although baseline Ca2+ is reduced. Each line in this panel (and, unless specified, in subsequent panels) represents the mean response of all animals of one genotype or condition. Error bars (lighter shading) in all panels show standard error of the mean. Gray areas indicate periods of higher O2 concentration; blue areas indicate periods with blue light (0.26 mW/mm2) on; orange areas indicate periods with green light (0.64 mW/mm2) on.
Figure 1—figure supplement 1. Simplified circuitry associated with the URX, AQR, and PQR neurons dissected in this paper.
