Fig. 5: Predatory aggression is dependent on conserved sensory neuron function.
From: Predatory aggression evolved through adaptations to noradrenergic circuits
a, Scanning electron microscopy image of the P. pacificus face. Six sensory endings from the IL2 neurons circle the mouth opening and are candidates for prey detection. b, klp-6p::GFP expression is specifically localized to IL2 neurons in P. pacificus. c, Probability density map of velocity and pumping rate for genetic silencing of IL2 neurons. Plots show WT + 10 mM histamine and klp-6p::HisCl without histamine controls and klp-6p::HisCl + 10 mM histamine silencing conditions. d, Relative time in each behavioural state for all conditions in c. Box plots follow Tukey’s rule with the box from first to third quartiles, and a line at the median. The whiskers denote 1.5× interquartile range. Statistics were performed with Mann–Whitney U-test using Bonferroni correction for multiple tests, against WT (black asterisks) and against Ppa-klp-6::HisCl − histamine (grey asterisks). n = 103 for WT, n = 107 for Ppa-klp-6::HisCl − histamine, n = 104 for Ppa-klp-6::HisCl + histamine. Minimum of three biological replicates. e, Average transition rates between behavioural states for WT + 10 mM histamine, klp-6p::HisCl without histamine and klp-6p::HisCl + 10 mM histamine silencing conditions. The number in circles indicates the average state duration as in d, and the arrow size indicates the transition rate normalized to outgoing transitions. f, Schematic phylogeny illustrating the evolutionary relationships among nematodes. Bold text indicates selected comparative species of interest. g, Differential interference contrast mouth images of the predatory A. sudhausi (top) and P. pacificus (middle) with mouths containing teeth-like structures (*) and the microbial feeder C. elegans (bottom) with an empty buccal cavity (arrow). h, Corpse assays of A. sudhausi WT compared with Asu-tbh-1 mutants that show reduced predatory aggression. C. elegans corpses were counted after 2 h of exposure to five predators. Statistics were performed with Mann–Whitney U-test. n = 10 for A. sudhausi, n = 10 for Asu-tbh-1. i, Proposed model of the octopamine/tyramine regulation driving aggressive versus docile behavioural states. Scale bars, 5 μm (a), 50 μm (b), 25 μm (g). *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.
