Type: Pharyngeal interneuron
In MoW: I1
Male Wiring Project: I1L, I1R
In Wormbase: I1, I1L, I1R
Lineage: AB alpapppaa, AB arapappaa
Location: Pharynx anterior bulb
Description: Pharyngeal interneurons. The anterior projections from these cells insert onto muscles pm1 and pm2s, and have a free subcuticular, proprioceptive-like (postulated sensory) ending at the anterior end. They also extend to the basement membrane here to receive input from the somatic RIP neurons. The posterior axonal projections of the I1s run within the subventral nerve cords and then run around the pharyngeal nerve ring to the dorsal side where they meet in gap junctions. The termination of the anterior projections in the dorsal pharyngeal nerve cord is variable (Albertson and Thomson, 1976).
Neurotransmitter: Express neuropeptide-like protein NLP-3 (Nathoo et al., 2001).
Function: The pharyngeal and somatic nervous systems are connected to each other via gap junctions between the extrapharyngeal RIP neurons and the pharyngeal I1 neurons. When this connection is disrupted by ablation of RIPs, pharyngeal pumping becomes unresponsive to light touch which is sensed by somatic touch neurons (Avery and Thomas, 1997). I1s also synapse on MC neurons and modulate the rate of pharyngeal pumping in the absence of bacteria (Avery and Thomas, 1997).
Receptor Expression: Express glutamate receptor subunits, GLR-7 and GLR-8 (Brockie et al., 2001). Suggested to express G-protein coupled muscarinic acetylcholine receptor ACM-2 (F47D12.2). acm-2 mutants display an increased pharyngeal pumping rate and an increased sensitivity to nicotine (Steger and Avery, 2001).