Mapping Glial Circuits Underlying Neuronal Function and Behavior in Drosophila. Taylor R. Fore¹, Camille Milton*¹, Alexander Nasr*¹, Kody McKay*², Jered Stowers¹, Hong Bao¹, Bing Zhang¹. 1) Department of Biology, University of Oklahoma, Norman, OK; 2) Department of Biological Sciences, Southwestern Oklahoma State University, Weatherford, OK.

   Behavior is carried out directly by motoneurons but it is highly influenced by a large network of cells, including sensory cells, interneurons, modulatory neurons, and muscles. Glial cells are an often-overlooked brain cell type in this process. Despite increasing interest in glia cells, their roles in the nervous system are still to be explored. Here, we offer a new approach to study the role of glial cells in neuronal function and behavior. Instead of focusing on specific genes and the consequence of their mutations, we undertake an unbiased genetic approach to screen for the critical subsets of glial cells that regulate behaviors in fruit flies. Once many different subsets of glial cells are identified, we will be able to identify specific glial partner neurons, probe glia-neuron connectivity, and examine the effect of neighboring glial cells on neuronal function and behavior. To achieve this objective, we express UAS-MJD:PolyQ⁷⁸ to perturb glial function and observe the effect on locomotion. Pan-glial expression of PolyQ⁷⁸ results in significant age-dependent defects in climbing and walking. At the cellular level, these behavioral defects are marked by a significant change in the morphology of both glia and neuronal circuits, as well as a dramatic change in NMJ physiology, underscoring the importance of glia in neuronal health. Utilizing the FINGR method (Bohm et al. 2010) enables us to unbiasedly refine glial circuits into smaller units and correlate behavioral changes to these circuits. Specifically, flies containing Tub>Gal80>; UAS-PolyQ; Repo-Gal4, UAS-GFP are crossed to a collection of enhancer-trap Flippase (FLPx2) lines. When FLPx2 expression overlaps with Repo-Gal4 positive cells, Gal80 is flipped out, resulting in selective activity in subsets of glial. This forward genetic screen has identified a number of positive FLPx2 lines, demonstrating the feasibility and success of mapping glial circuits involved in locomotion.