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Rein et al., 2002 Current Biology

The mushroom bodies (MBs) in the adult Drosophila brain. Rein et al., 2002 Current Biology. from Martin Heisenberg. modified from Armstong et al., Learning & Memory 1998. A wild-type  neuron.  lobe.  vertical branch. 10 m m. 10 m m.  lobe.  horizontal branch. midline.

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Rein et al., 2002 Current Biology

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  1. The mushroom bodies (MBs) in the adult Drosophila brain Rein et al., 2002 Current Biology

  2. from Martin Heisenberg

  3. modified from Armstong et al., Learning & Memory 1998

  4. A wild-type  neuron  lobe  vertical branch 10mm 10mm  lobe  horizontal branch midline Srausfeld et al., MRT 2003 10mm 10mm

  5. Developmental Geneticsof  mushroom bodies (MB)  • MB are involved in olfactory learning. • MB are relatively well described structure in the adult central brain. • 4 neuroblasts in each hemisphere form one MB. • Flies without MB are viable and fertile. • Good markers of MB (Gal4 lines, antibodies) • Clonal analysis (positive labelling : Gal 80)

  6. Development of the Drosophila mushroom bodies: sequential generation of three distinct types of neurons from a neuroblast Lee et al., Development 1999 MARCM Mosaic analysis with a repressible cell marker for studies of gene function in neuronal morphogenesis Lee and Luo Neuron 1999

  7. Neuroblasts in the head and trunk Noveen et al., Development 2000

  8. Noveen et al., Development 2000

  9. The MB primordia in the embryonic brain (frontal view) KCs, Kenyon cells (MB cells) Development of the MBs. (A) Embryonic MB primordium (lateral view). (B) Larval MB. (C) Late pupal and adult MBs.

  10. The GAL4/UAS system Brand & Perrimon, Development 1993

  11. + w h i t e G a l 4 mCD8-GFP UAS Visualise MBs

  12.  neurons (cell bodies + dendrites + axons) of the MBs in one particular GAL4 line

  13. ’’ axons (and neurons) of the MBs some midline axons are also labeled in another GAL4 line

  14. /' '/ MUSHROOM BODY SPECIFIC GAL4 LINES GAL4-OK107 GAL4-201Y GAL4-c739  • AXONS core AXONS ALL AXONS  AXONS   a’ acore b b b’ bcore g g

  15. x Marking mutant clones in a mosaic organism by the MARCM technique Mitotic recombination After DNA replication Two distinct mosaic progeny Parental cell x Repressor protein Repressible marker x x x x x x x Mutant FRT x Centro mere Repressor NB: one can make clones in wild-type background also!: visualisation clones

  16. A single photoreceptor can be traced from cell body in eye disc (arrow in left panel) to the end of the extending axon in the optic lobe (arrow in right panel) e: eye disc b: brain

  17. An adult MB neuroblast clone with five axonal bundles (3 medial and 2 dorsal). This clone was generated by inducing mitotic recombination in newly hatched larva

  18. Three models of the projection of the MB neuroblast progeny (A) One neuroblast progeny project to a specific region, e.g. the  lobe( black cells) (B) A MB neuroblast clone contributes to the entire cellular repertoire of the MB (C) The progeny of the MB neuroblast are not confined to the MB. Some neurons project to other region of the brain.

  19. Summary of the structural organisation of the MB Each MB neuroblast generates a clonal unit that contains all the types of cells (B) The intact MB is a fourthfold structure of these clonal units

  20. Two mutually exclusive types of marked clones. Either all postmitotic neurons generated subsequently in the same lineage will be labeled (upper), or only two neurons derived from the GMC will be labeled in the whole lineage (lower). N N G FLP Nb A multi-cellular Nb clone FLP Two cell clones

  21. In addition, mitotic recombination in a dividing GMC can generate a single cell clone FLP Single-cell clone

  22. A two cell clone

  23. Three types of neurons:  , ’’ and  The question is: how are they generated from a single neuroblast?

  24. Lobe compositions of MB neuroblast clones generated at different stages

  25. Sequential generation of three distinct types of MB neurons with characteristic axonal projections

  26. Morphological characterization of the three types of MB neurons

  27. Different behaviors of and ’’ neurons during metamorphosis Clones were generated at NHL for A and D, at early L3 for B and E, at late L3 for C and F. Morphologies were examined just before PF (A-C) or 18 h APF (D-F)

  28. Axon reorganization of  neurons during metamorphosis. Clones were generated in NHL and examined 12, 18 and 24 hours APF

  29. Summary of the mushroom body development

  30. - a/b - a’/b’ 3 types of neurons 1 neuroblast - g 2 x 4 neuroblats 2 x 2000 neurons 2 x 1 MB brain = central brain + optic lobes = 200.000 neurons central brain = central complex + MB central complex = 20.000 neurons 2 X MB = 2 X 2.000 neurons = 4000 neurons

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