Manipulating the remodeling of glial ensheathment of peripheral nerves during metamorphosis. Matthew Siefert, Soumya Banerjee, Sayantan Mitra, Jack Wilber, Joyce Fernandes. Zoology, Miami University, Oxford, OH.

   Larval peripheral nerves are surrounded by 3 layers of glia (Stork et al., 2008). During metamorphosis these layers are reorganized in 5 pairs of posterior abdominal nerves (A4-A8) which come together to form a terminal nerve trunk (TNT). The most external glial layer, the perineurial layer, makes up a large proportion of the total glia, 81.2%% (n=6) along the A3 nerve, 83% (n=12) along the A4 nerve, 85.2% (n=8) along the A5 nerve, 72% (n=6) along the A6 nerve. To probe the role of this glial layer during the formation of the TNT, we manipulated it by selectively targeting UAS-reaper using c527Gal4. When reaper is expressed during the first 24 hours of pupal development period, 66% (n=12) of animals showed defects in TNT formation. Posterior sections of the TNT remain unfused, and more anteriorly, the patterns of defasiculations become altered. There is a significant reduction in the number of glial cells by 24h APF along segmental nerves. Analysis of peripheral nerves A3 through A5 has revealed a 32.8% (n=5, p value = 0.0002), 11.2% (n=7, p value = 0.046), and a 15.1% (n=6, p value = 0.013) decrease in glial cells along A3, A4, and A5 nerves, respectively. These data suggest a role for perineurial glia in remodeling of peripheral nerves during metamorphosis. To ensure a more efficient elimination of glial cells, we are in the process of targeting Diphtheria Toxin using c527gal4. We also plan to prevent remodeling of the perineurial layer by targeting dominant negative shibire. Results from both sets of ongoing experiments will be presented.