Monoaminergic Orchestration of Motor Programs in a Complex C. elegans Behavior
(A) A composite DIC image with fluorescent overlay showing that the Pser-2::mCherry transcriptional reporter is expressed in head muscles, head neurons, and neurons in the ventral nerve cord. (B–D) Transgenic animal showing coexpression of Pser-2::mCherry (B) and Punc-47::GFP, which labels all GABAergic motor neurons (C). Pser-2::mCherry is strongly expressed in the GABAergic VD neurons but not the DD neurons (D). Anterior is to the left. Scale bar is 20 µm. (E) Exogenous tyramine induces immobilization though the activation of SER-2 and Gαo signaling pathway in the GABAergic neurons. Shown is the percentage of animals that become immobilized after 10 min on 30 mM tyramine. Loss-of-function of unc-25 (glutamic acid decarboxylase) suppresses the tyramine resistance of ser-2 mutant animals. unc-25 (GABA deficient) mutants and unc-25; ser-2(pk1357) double mutants are not resistant to the paralytic effects of exogenous tyramine. Expression of SER-2 in all GABAergic neurons (Punc-47::SER-2) restores sensitivity of ser-2 mutants to exogenous tyramine. Expression of GOA-1/Gαo or EAT-16/RGS in all GABAergic neurons (Punc-47::GOA-1 or Punc-47::EAT-16) partially restores sensitivity to exogenous tyramine in the respective goa-1 and eat-16 mutants. Each bar represents the mean ± SEM for at least three trials, totaling a minimum of 30 animals.