Calcineurin and Protein kinase G regulate C. elegans behavioral quiescence during locomotion in liquid

We have previously reported that high cholinergic signaling promotes quiescence and command interneurons are critical for timing the quiescence bout durations. We have found that in addition to command interneurons, sensory neurons are also critical for quiescence. We show that the protein phosphatase calcineurin homolog tax-6 promotes swimming whereas the protein kinase G homolog egl-4 promotes quiescence. tax-6 expression in the sensory neurons is sufficient to account for its effect. egl-4 also acts in multiple sensory neurons to mediate its effect on quiescence. In addition our data is consistent with regulation of quiescence by egl-4 acting functionally downstream of release of acetylcholine (ACh) by motor neurons.Our study provides genetic evidence for mechanisms underlying the maintenance of a behavioral state operating at multiple neuronal levels through the activities of a kinase and a phosphatase. These results in a genetically tractable organism establish a framework for further dissection of the mechanism of quiescence during episodic behaviors.Most natural behaviors are characterized by transitions between distinct behavioral states determined by the internal state of an organism as well as spatial and temporal variance of the environment. Observations of leech long-term behavior in an unstructured environment have resulted in identification of several behavioral states, including stationary states, and transitions between these states that depend only on the most recent prior behavioral state [1,2]. Invertebrate electrophysiological studies of a given behavioral state such as quiescence and switching between behavioral states e.g. swimming and crawling in Tritonia [3,4], swallowing and quiescent states in Lymnea [5] among many others have elucidated several neuronal mechanisms. However the genetic basis of these processes are less well studied.Despite a single gait underlying locomotion in liquid and solid media [6], referred to as swimming [7,8] and c