Figure 2.

Schematic diagram of the neurotransmitter controlled behaviors and the associated mutant used in this study. The CAT-2 gene encodes for tyrosine hydroxylase and is the primary pathway for dopamine (DA) synthesis. Serotonin synthesis requires the TPH-1 tryptophan hydroxylase gene. Serotonin is removed from the synaptic space by the MOD-5 serotonin reuptake transporter. MOD-1 receptor encodes an ionotropic 5HT receptor and SER-4 belongs to the class of metabotropic G-protein-coupled 5HT receptors, and is homologous to mammalian 5-HT1 receptor class. The drug aldicarb is a cholinesterase inhibitor that causes an accumulation of acetylcholine at the neuromuscular junction, which eventually leads to paralysis. Exogenous 5-HT can inhibit this behavior. 5-HT stimulates egg-laying in C. elegans and both dopamine and acetylcholine inhibit it.