| Olfactory processes have been extensively studied in the nematode worm Caenorhabditis elegans, but much remains unclear regarding both the initial steps of olfactory signal discrimination and components further downstream, in which olfactory memories act to guide behavior. In this work, we identify lrn-3(mm200), a mutant with a broad range of olfactory learning deficits, using a novel screening approach. We then turn to the longstanding question of how worms are able to discriminate between odorants whose signals are transduced via the same secondary messengers, in the same neuron, and show that the apparent discrimination is the result of arrestin-mediated desensitization of odorant receptors. Finally, we show differential signaling by minor G-protein alpha subunits does not play a role in behavioral plasticity after olfactory learning. These experiments demonstrate a rapid technique for identification of learning mutants, and suggest that olfactory discrimination in C. elegans may be more limited than previously thought. |
