(A) camt-1(db973) and camt-1(ok515) mutants (see also (B)) exhibit altered locomotory responses to 21% O2 and hyperactive movement at 7% O2. (B) The domain organization of CAMT-1, highlighting camt-1 loss of function mutations used in this study. (C) A WT copy of the camt-1 genomic locus rescues the O2-response defects of camt-1(db973) mutants. (D) CAMT-1a::GFP driven from its endogenous regulatory sequences in a recombineered fosmid is expressed widely in the nervous system. (E) camt-1(db973) mutants exhibit an increased turning frequency both in the presence and absence of a CO2 stimulus. Assays were performed in 7% O2. (F) camt-1(ok515) mutants show defects in chemotaxis to NaCl, benzaldehyde (Benz), and diacetyl (DI), which can be rescued by expressing a WT copy of CAMT-1. Colored bars indicate the mean and error bars indicate the SEM. (G) The O2-response defects of mutants harboring amino acid substitutions in the CG-1 DNA-binding domain (db1258, db1259, and db1260 alleles; see also Figure 1—figure supplement 1B), are comparable to those of a camt-1(ok515) deletion mutant. (B, C, E, G) Lines indicate average speed and shaded regions SEM, black horizontal bars indicate time points used for statistical tests. (B, C, E–G) Mann-Whitney U-test, ns: p≥0.05, *: p<0.05, **: p<0.01, ***: p<0.001. Number of animals: n≥22 (A), n>41 (C), n≥23 (E), n≥4 assays for each genotype (F), n≥56 (G). ANK, ankyrin domain; CaMBD, calmodulin-binding domain; CG-1, DNA-binding domain; IPT/TIG, Ig-like, plexins, transcription factors or transcription factor immunoglobulin; IQ, calmodulin-binding motif; NES, nuclear export signal; NLS, nuclear localization signal; VNC, ventral nerve cord; WT, wild-type.