Glia/Axon connections in the peripheral nerve of Drosophila melanogaster

The Drosophila nervous system is protected by blood barriers composed of a layer of subperineurial glia, tightly bound together by septate junctions. Previous studies have shown the structure of septate junctions have high similarity to paranodal junctions in vertebrates. Paranodal junctions are formed between glia and axons in the myelinating glia that flank the Nodes of Ranvier. Although the process of myelination does not exist in Drosophila, there is evidence that a similar structure may be formed at the distal end of the Drosophila peripheral nerve. Study of the conserved subunits between septate junctions and paranodal junctions will help direct future studies on how glial cells regulate the barrier formation in the nervous system. Thus, we have focused on the degree of glia-axon contact and the formation of septate junctions between subperineurial glial cells and the axon membrane in larval and adult nerves and at the neuromuscular junction (NMJ). We demonstrate that GFP reconstitution across synaptic partners (GRASP) can be utilized to show that glial cells are in contact with axon membranes. Glia surround nerves in both adult and larva; however, the boutons of the adult NMJ are partially covered by glia, while there is not a consistent presence of glia in the larval NMJ. Septate junctions and the subperineurial glia stop at the distal end of motor axons but do not extend into either the larval or adult NMJ. We found the loss of septate junction components in axon does not lead a significant impact on larval locomotion speed and adult proboscis extension response.Science, Faculty ofZoology, Department ofGraduat