Ogre protein distribution in an ogre mutant adult optic lobe.
Image showing an optic lobe (center of each frame) and part of the brain (to the right of each frame) in a fly of genotype:-
ogrejnl3 / Df(1)Sxlbt ; nrv2GAL UAS-mCD8:GFP / +
The nervous system can be seen due to GFP (green) expression in cortex and neuropile glia, driven under the transcriptional control of nrv2GAL4 (Sun et al, 1999). All flies of this genotype exhibit very small, disorganised, optic lobes like those described for ogre viable mutants and escapers of lethal alleles (Lipshitz and Kankel, 1985). Almost no glial processes remain in the optic lobes of these mutant flies whereas glial architecture features prominently in wild type optic lobes. In contrast, the mesh-like processes of cortex glia near the brain exterior display only slight defects in the ogre mutant (ogre mutant glial defects). This brain has been antibody stained to detect any remaining endogenous Ogre using a rabbit anti-Ogre polyclonal antibody (red). It's not surprising that some Ogre expression remains in this genotype or the adult flies would not eclose - ogre null alleles are pharate lethal (Lipshitz and Kankel, 1985). All of the Ogre-positive immunoreactivity lies near the nervous system periphery, often in long interlinked lines (see Ogre distribution on an ogre brain) - probably the cellular junctions between perineurial cells. Expression of a UAS-Ogre construct via nrv2GAL4 can partially rescue the size and glial structure phenotypes of the ogre mutant to varying degrees (see images: good rescue, poor rescue).