Innexin (Ogre) protein distribution in the adult brain
Figure legend: A single optical section near the front of the adult Drosophila brain showing the region corresponding to the grey box in the brain illustration above. Endogenous Ogre protein (purple)(see Ogre summary), revealed by a rabbit polyclonal Ogre-specific antibody, has a punctate distribution. Larger punctae presumably represent gap junction plaques. Smaller punctae could be smaller plaques or may be internal vesicles (see Internal innexin vesicles and Annular junctions). Comparison of Ogre staining with the glial reporter nrv2-GAL4 / UAS-mCD8:GFP (green) reveals that large Ogre plaques coincide with thick glial processes in cortex glia (CG) and in neuropile glia ensheathing the mushroom body lobes (α, β/γ, arrows). Hovering the mouse over the image should highlight the position of the mushroom body structure. The images on this page indicate that Ogre (and Inx2 + Inx3 which exhibit similar distributions) are extensively expressed in many glial cell types throughout the brain, possibly constructing a large glial syncytium like that proposed to exist in vertebrate brains (Wallraff et al. 2006, Nagy and Rash, 2003). Size bar = 20μm.
Figure legend: Single optical section through the same brain as that shown at the top of the page. The current optical section is approximately in the middle of the brain. Again, the largest Ogre plaques (Purple) coincide with cortex glia (CG, near top of image panels) and neuropile glia (NG) ensheathing the mushroom body pedunculus (Ped - seen as a cross-section, arrow) and the ellipsoid body (EB) of the central complex. Size bar = 20μm.
Figure legend: Confocal section through the adult brain near the posterior surface (same brain as other photos on this page). The most intense Ogre staining (purple) is detected in cortex glia (CG) and in glia surrounding the mushroom body calyx and the protocerebral bridge (PB) of the central complex. The edge of a single perineurial cell (PN, arrow) is in the plane of focus and also stains strongly for Ogre protein. All of the innexins, Ogre, Inx2 and Inx3 are also found as large punctae on the very exterior of the brain - which does not correspond to any nrv2-GAL4 / UAS-mCD8:GFP fluorescence. We hypothesize that these represent innexins within the population of surface glia - cells in which nrv2-GAL4 is reportedly not expressed (Dumstrei et al. 2003), however, an inx2-GAL4 enhancer trap line may drive reporter expression in surface glia.