Odorant-induced membrane potential depolarization of AIY interneuron in Caenorhabditis elegans

Although some interneurons in C. elegans have been shown to have unusual region-specific Ca²⁺ dynamics, the region-specific Ca²⁺ and membrane potential response properties of these neurons are largely unknown due to technical limitations. In this report, we focused on one of these neurons, AIY interneuron, where Ca²⁺ dynamics have been detected only in neurites, and not the soma, during odor and temperature stimulation to determine whether membrane potential and Ca²⁺ are region-specific dynamics and distinct from one another. To visualize voltage change both in the soma and neurites of AIY, we used voltage-sensitive fluorescent protein (VSFP) 2.42. First, we confirmed that the sensor protein worked correctly in C. elegans by depolarizing AIY interneuron with high concentrations of KCl. Next, we observed membrane potential depolarization during odor (isoamyl alcohol) stimulation in both neurites and the soma. Additionally, depolarization of membrane potential with direct application of high KCl induced a Ca²⁺ increase in the soma. From these results, we conclude that membrane potential behavior and Ca²⁺ dynamics in AIY differ in its subcellular regions and that VSFP2.42 can be a useful tool for studying information processing in single neurons.