Figure 2. BAG neurons are required for CO₂ response in free-living and parasitic nematodes.

A. Parasitic IJs and C. elegans dauers are attracted to CO₂ in a chemotaxis assay (Figure S2A). n = 5–6 trials for each species. B. CO₂ induces jumping by S. carpocapsae in a jumping assay (Figure S2B). n = 4–11 trials. C–E. BAG neurons are required for CO₂ attraction in H. bacteriophora and S. carpocapsae IJs, and C. elegans dauers. n = 12–34 worms for each treatment (C–D) or n = 18–29 trials (E). The assay in E was a 10 min. assay, since the difference between wild-type and BAG- animals was apparent after only 10 min. F. BAG neurons are required for CO₂-evoked jumping by S. carpocapsae IJs. n = 10–18 worms for each treatment. ***, P<0.001; *, P<0.05, Fisher’s exact test (C, D, F) or unpaired t test (E). Error bars represent SEM. For C, D, and F, y-axis values represent the percentage of worms that yielded a positive behavioral response; error bars are not present because each worm was scored once individually. AWC chemosensory neurons were ablated as a control. 10% CO₂ was used for all experiments. See also Figure S2 and Movie S2.