The glia of the adult <i><scp>D</scp>rosophila</i> nervous system

TLDR

Glia are essential for nervous system development and homeostasis, yet adult Drosophila glia remain poorly studied compared to embryonic stages. The study aims to provide a comprehensive description of adult Drosophila glia and a genetic toolkit to enable functional analyses. This was achieved by analyzing ~500 glial drivers from a collection of synthetic GAL4 lines. Glia constitute about 10 % of nervous system cells, envelop all neuronal compartments, follow simple morphogenetic rules, minimize glial–glial contact while maximizing neuron contact, and lack spatial organization relative to neurons. GLIA 2017; 65:606–638.

Abstract

Glia play crucial roles in the development and homeostasis of the nervous system. While the GLIA in the Drosophila embryo have been well characterized, their study in the adult nervous system has been limited. Here, we present a detailed description of the glia in the adult nervous system, based on the analysis of some 500 glial drivers we identified within a collection of synthetic GAL4 lines. We find that glia make up ∼10% of the cells in the nervous system and envelop all compartments of neurons (soma, dendrites, axons) as well as the nervous system as a whole. Our morphological analysis suggests a set of simple rules governing the morphogenesis of glia and their interactions with other cells. All glial subtypes minimize contact with their glial neighbors but maximize their contact with neurons and adapt their macromorphology and micromorphology to the neuronal entities they envelop. Finally, glial cells show no obvious spatial organization or registration with neuronal entities. Our detailed description of all glial subtypes and their regional specializations, together with the powerful genetic toolkit we provide, will facilitate the functional analysis of glia in the mature nervous system. GLIA 2017 GLIA 2017;65:606–638