Figure 4.

Hyperoxia Avoidance Suppresses SIS in npr-1 Mutants

(A) npr-1(lf) animals are more likely to engage in SIS when bordering or aggregating than when solitary. Animals were exposed to UV light or mock treated and 60 min later categorized as solitary, bordering, or aggregating as described in methods and examined for locomotor quiescence. Wild-type animals rarely aggregate, hence the low n for this category. Mean and SEM of three trials of 50 animals per trial are shown, and the total number of animals in each category is indicated. *p < 0.05, ns, not significant versus solitary animals of same genotype, one-way ANOVA with Dunnett's multiple comparisons test. For a time course of bordering and aggregation behavior during SIS, see Figure S1.

(B) Wild-type N2 and npr-1(lf) animals were exposed to Cry5B for 10 min, transferred to plates containing E. coli OP50, placed into a Hammond chamber, and exposed to controlled oxygen conditions as described in methods. npr-1(lf) are sustainably aroused by ambient oxygen (21%) but quickly become quiescent in response to low oxygen (10%).

(C and D) Genetic components of oxygen sensation are required for arousal of npr-1(lf) animals from SIS. Animals were exposed to either Cry5B (C) or UV light (D) as SIS triggers and examined for locomotor quiescence. Impairment of the hyperoxia avoidance response, using gcy-35(ok769) or osm-9(ky10), abrogates the SIS defect of npr-1(ad609) animals. Mean and SEM of three trials of at least 25 young adult animals per trial are shown. ****p < 0.0001 double mutants versus npr-1(ad609), two-way RM ANOVA with Sidak's multiple comparisons test.