| Organisms survive based on their ability to collect input from the environment in which they exist and translate that information into behavioral output. The nervous system is responsible for interpreting sensory information and organizing a response. One mechanism of communication in neurons employs ligand-gated ion channels, which underlie a diverse range of behaviors. In C. elegans, studies of ligand-gated ion channels indicate a diverse family of receptors. Even within specific neurotransmitter families, there is diversity in function and purpose. GABA-mediated behaviors in C. elegans include foraging, defecation, locomotion, and mating. The experiments in this thesis were aimed at understanding how GABA-mediated excitation of the postsynaptic cell can regulate these behaviors.;Previous work indicated exp-1, a GABA gated cation channel, was involved in mediating the contraction of the intestinal muscles and anal depressor muscles. We characterized exp-1 homolog, lgc-35. lgc-35 mediates the sphincter contraction step during enteric muscle contraction. When expressed in oocytes, LGC-35 forms a GABA receptor that passes positively charged ions (cations). As expected, lgc-35 plays a role in defecation. However, surprisingly, lgc-35 is expressed not only in the sphincter muscle, but also in regions known to control and mediate locomotion and mating. Locomotory defects were observed in lgc-35 mutants, suggesting a role in decision making for duration of locomotion. In lgc-35 male mutants, males were less likely to maintain an everted spicule during mating; however, mating ability was not effected, suggesting a role for lgc-35 in spicule eversion. This work describes the last known excitatory GABA receptor in C. elegans. |
