Disorganised mushroom body neuronal architecture in an ogre mutant.
Various defective mushroom body (MB) architecture phenotypes are observed in ogre mutant genotype flies. Panels A and B show the MB lobe region of normal flies (control and wild type). All other figures are of ogre mutant brains. Images B, K and L show MBs stained using a primary antibody specific for FasII (purple). All other images show MB morphology revealed by expressing UAS-mCD8:GFP in a subset of MB neurons under the transcriptional direction of the 201YGAL (Yang et al, 1995) driver line. A, MB
lobe morphology in a control genotype: Df(1)Sxlbt / +
-MB structure looks normal. The α and β/γ lobe positions are labelled and a dashed line indicates axons of the median bundle at the brain midline. All subsequent images are in the same orientation. B, FasII staining of a wild type brain reveals a greater level of staining than 201yGAL4 in all three lobes, α, γ and the β-lobe as well as some non-MB neurons. C, few ogre mutant MB axons express mCD8:GFP at wild type levels in most of the brains examined. Here, some axons expressing GFP at normal levels cross the midline (arrow). D, Very weakly staining axons. Abnormally shaped β/γ lobes fuse across midline (arrow). E, Multiple neuronal fascicles traverse the midline (arrows). α lobe is thin and miss-shapen towards tip (*). F, β/γ lobe axons extend in abnormal directions (arrows) and cross the midline. α lobe is missing. k-Kenyon cell bodies. p-pedunculus. G, A single strongly staining axon bifurcates at the base of the pedunculus (arrow) but both processes enter the α lobe. Axons then travel in abnormal directions (arrowheads). Abnormally large spots of mCD8:GFP appear along axons (*). H, MB axon bifurcates normally (arrow) extending a process into the α and β/γ lobes. Anomalous U-turn occurs in the β/γ lobe axon (arrowheads). I, α lobe has abnormal shape(*). mCD8:GFP has punctate pattern in calyx (c) and at tips of β/γ lobes (arrow) and at the base of the pedunculus (p). J, β/γ lobes fuse across midline in mass of mCD8:GFP spots. Tip of α lobe has irregular outgrowth (*). Inset shows another α lobe outgrowth extending in an arc from the tip of the α lobe. K, FasII staining is often weak in ogre mutant flies. α lobe tip is miss-shapen (*) and β/γ lobes bunch up (arrow, phenotype occurs in 9/66=14% of brains). FasII immunoreactivity in the mutant often appears spotty. Inset, arc shaped axonal outgrowth at tip of α lobe. L, FasII staining reveals two strongly staining median tracts (arrowheads). Possibly α lobe axons parallel to the β lobe. The α lobe is spotty and almost devoid of normal axonal projections. Size bars are 20μm.