Molecular encoding and synaptic decoding of context during salt chemotaxis in C. elegans

Animals navigate toward favorable locations using various environmental cues. However, the mechanism of how the goal information is encoded and decoded to generate migration toward the appropriate direction has not been clarified. Here, we describe the mechanism of migration towards a learned concentration of NaCl in Caenorhabditis elegans. In the salt-sensing neuron ASER, the difference between the experienced and currently perceived NaCl concentration is encoded as phosphorylation at Ser65 of UNC-64/Syntaxin 1 A through the protein kinase C(PKC-1) signaling pathway. The phosphorylation affects basal glutamate transmission from ASER, inducing the reversal of the postsynaptic response of reorientation-initiating neurons (i.e., from inhibitory to excitatory), guiding the animals toward the experienced concentration. This process, the decoding of the context, is achieved through the differential sensitivity of postsynaptic excitatory and inhibitory receptors. Our results reveal the mechanism of migration based on the synaptic plasticity that conceptually differs from the classical ones. The nematode C. elegans moves around to find an optimal environment. This work demonstrates how it can detect and move towards a previously learned salinity using the salt-sensing neuron ASER.

Automated summary

This study reveals the synaptic plasticity-based migration mechanism in Caenorhabditis elegans, where the experienced and currently perceived salt concentration difference is encoded by the salt-sensing neuron ASER, affecting the postsynaptic response of reorientation-initiating neurons and guiding animals towards the experienced concentration.