Meeting Abstract
3.6 Saturday, Jan. 4 09:15 Dopamine and serotonin are responsible for locomotor gait transitions in C. elegans. VIDAL-GADEA, AG*; TOPPER, S; YOUNG, L; KRESSIN, L; ELBEL, E; BRETTMANN, L; WARD, KA; PIERCE-SHIMOMURA, JT; The Univ. of Texas at Austin, Austin; The Univ. of Texas at Austin, Austin; The Univ. of Texas at Austin, Austin; The Univ. of Texas at Austin, Austin; The Univ. of Texas at Austin, Austin; The Univ. of Texas at Austin, Austin; The Univ. of Texas at Austin, Austin; The Univ. of Texas at Austin, Austin agvg75@gmail.com
Transition between motor gaits is a task shared among many species. Its failure often has devastating consequences for the organism. The nematode C. elegans is a small worm adapted for locomotion on land and in water. It remains controversial if swimming and crawling are distinct gaits in C. elegans and if this was the case, how transitions between them are accomplished. Answering these questions could enable its use to study the mechanisms underlying locomotory transitions. We used an interdisciplinary approach spanning in depth behavioral assays, mechanic and optogenetic stimulation, laser ablations, mutant analysis, and in vivo photolysis of caged amines to test whether C. elegans uses distinct gaits and to determine how they transition between them. We show that in C. elegans crawling and swimming are distinct gaits. Dopamine released by a subset of mechanosensory neurons is necessary and sufficient to initiate and maintain crawling by a pathway activating D1-like receptors. Conversely, serotonin is necessary and sufficient to initiate and maintain transition from crawling to swimming and to inhibit a set of crawl-specific behaviors. These transitions appear to be modulated by the balance between these biogenic amines. Both amines have been found to play crucial roles in transition between alternate locomotory forms in diverse species stressing the importance locomotor transitions have for survival. Further study of locomotory switching in C. elegans may provide insight into the evolution of motor gaits across animal taxa.
