Growing Pains: Development of the Larval Nocifensive Response in Drosophila

TLDR: It is found that prior to the third instar, larvae are unable to perform the characteristic “corkscrew-like roll” behavior and an avoidance behavior consistent with a nocifensive response that is present immediately after larval hatching is identified, representing a paradigm that may be useful in examining mutations with an early lethal phenotype.

Abstract: The ability to perceive and avoid harmful substances or stimuli is key to an organism's survival. The neuronal cognate of the perception of pain is known as nociception, and the reflexive motion to avoid pain is termed the nocifensive response. As the nocifensive re- sponse is an ancient and evolutionarily conserved behav- ioral response to nociceptive stimuli, it is amenable to study in relatively simple and genetically tractable model systems such as Drosophila. Recent studies have taken advantage of the useful properties of Drosophila larvae to begin eluci- dating the neuronal connectivity and molecular machinery underlying the nocifensive response. However, these studies have primarily utilized the third-instar larval stage, and many mutations that potentially influence nociception sur- vive only until earlier larval stages. Here we characterize the nocifensive responses of Drosophila throughout larval de- velopment and find dramatic changes in the nature of the behavior. Notably, we find that prior to the third instar, larvae are unable to perform the characteristic "corkscrew- like roll" behavior. Also, we identify an avoidance behavior consistent with a nocifensive response that is present im- mediately after larval hatching, representing a paradigm that may be useful in examining mutations with an early lethal phenotype.