Partial rescue of optic lobe glia in an ogre mutant.
The image shows serial sections taken through the optic lobe of an animal of genotype:-
ogrejnl3 / Df(1)Sxlbt ; nrv2GAL UAS-mCD8:GFP / UAS-ogre2UO15
...it is genetically mutant for ogre ( due to ogrejnl3 / Df(1)Sxlbt) but also expresses rescue constructs (using the GAL4/UAS system, nrv2GAL/UAS-ogre).
ogre flies that do not express the UAS-ogre construct have very small optic lobes (shown here) whereas the rescue genotype flies have larger optic lobes - but still not up to wild type size. Glial architecture (green) is partially rescued (compared to wild type), however, this is an example of the best rescue observed using this genotype. An example of the other end of the rescue spectrum can be seen here. The nrv2GAL4 (Sun et al, 1999) line drives expression in glial cells (at least in the adult nervous system), so we assume the partial rescue of glial architecture and optic lobe size is due to Ogre expression in developing glia. It would be informative to see if rescue was similar or better using GAL4 lines that drive expression in neuroblasts, or at least in other lines that express in glia only (such as GCM-GAL4 - glial cells missing), or both glia and neurons. It's been reported that expression of UAS-ogre in all neurons via the pan-neural elav-GAL4 driver fails to exert any rescue of the optic lobe size phenotype although it partially rescues an electroretinogram defect observed in ogre flies (Curtin et al, 2002).