Monoaminergic Orchestration of Motor Programs in a Complex C. elegans Behavior
(A) Distribution of touch-induced reversals ending in an omega turn. Omega turns are more likely to occur after longer reversals (>3 body bends). Wild-type and ser-2 mutant animals initiate omega turns at the same rate (n≥150 per genotype). (B) Schematic representation of the omega angle. The omega angle was measured as the angle from the deepest point in the ventral bend to the closest points anterior and posterior of the animal. Images were adapted from movies of animals in the most ventrally contracted state of the escape response. (C) Percent of omega turns where the animal's nose touches the tail during the execution of the turn (closed omega turn). ser-2 mutants [ser-2(ok2103), n = 52; ser-2(pk1357), n = 6 2] touch nose to tail less frequently than wild-type (n = 51) in omega turns induced by both touch (Movies S4 and S5) and blue light in a Pmec-4::ChR2 background [Pmec-4::ChR2, n = 38; ser-2(ok2103); Pmec-4::ChR2, n = 43; ser-2(pk1357); Pmec-4::ChR2, n = 28]. Tyramine/octopamine-deficient tdc-1 mutants touch nose to tail less frequently than wild-type [tdc-1(n3420), n = 144], while octopamine-deficient tbh-1 mutants close omega turns like the wild-type [tbh-1(n3247), n = 153]. Genomic rescue lines partially restore this omega turning defect (ser-2 rescue line 2, n = 20; ser-2 rescue line 3, n = 21). (D) Average omega angle measured after touch or exposure to blue light in a Pmec-4::ChR2 background [Pmec-4::ChR2, n = 38; Pmec-4::ChR2; ser-2(ok2103), n = 43; Pmec-4::ChR2; ser-2(pk2103), n = 28]. ser-2 mutants [ser-2(ok2103), n = 52; ser-2(pk1357), n = 62] and tyramine/octopamine-deficient mutants [tdc-1(n3420), n = 35] make a wider omega turn than wild-type (n = 51). Octopamine-deficient tbh-1 mutants do not make wider omega turns [tbh-1(n3247), n = 16]. Genomic rescue lines partially restore the omega angle defect of the mutants (ser-2 rescue line 2, n = 20; ser-2 rescue line 3, n = 21). (E) Escape angles were measured from the direction of the reversal (induced by gentle anterior touch) to the direction of reinitiated forward locomotion. (F) Distribution of escape angles. Dashed grey line indicates average. Wild-type animals and tbh-1 mutants escape in the opposite direction from the touch stimulus [wt, 179°±5°, n = 42; tbh-1(n3427), 177°±11°, n = 16]. ser-2 mutants and tdc-1 mutants make a shallower escape angle [ser-2 (ok2103), 157.5°±5°, n = 53; ser-2(pk1357), 150°±5°, n = 46; tdc-1(n3420), 143.3°±6°, n = 35]. Genomic rescue lines restore the escape angle to wild-type levels (ser-2 rescue line 2, 173°±7°, n = 12; ser-2 rescue line 3, 168.5°±5°, n = 20). Rescue denotes the transgenic line Pser-2::SER-2; ser-2(pk1357). Error bars depict SEM. Statistical differences calculated from wild-type unless otherwise indicated: *p<0.05, **p<0.01, ***p<0.001, two-tailed Student's t test.