1. Jean-Maurice Dura Institut de Génétique Humaine
M1 Neurosciences Neurobiologie du Développement HMBS116
année 2017/2018
Jeudi 27 Septembre 9h45 SC 25.05
Jeudi 18 Octobre 9h45 SC 20.02
Jeudi 25 Octobre 9h45 SC 20.02
Jeudi 8 Novembre 9h45 SC 25.01
Jeudi 15 Novembre 8h SC 25.01
Jeudi 22 Novembre 8h SC 16.01
Neuronal remodeling:
Luo and Leary Annu Rev Neurosci 2005
Schuldiner and Yaron Cell Mol Life Sci 2015
Boulanger and Dura Biochim Biopys Acta 2015
Yaniv and Schuldiner WIREs Dev Biol 2016

2. Awasaki and Lee after Boulanger at al., Nature Neuroscience 2011

3. myoglanin (myo) encodes a Drosophila TGF-b ligand
early L3
middle L3
wandering L cortex layer
wand. L inner brain region
Expression of myo transcripts in the larval brain
Signals of myo transcripts (arrows) colocalized with the cell bodies of cortex glia and astrocyte-like glia
Awasaki Nat Neur 2011

4. Effect of glial silencing of myo on MB remodeling
Awasaki Nat Neur 2011

5. Expression of EcR-B1 in control and repo>myo-miRNA wandering L3
Awasaki Nat Neur 2011

6. Glial TGF-b governs neural remodeling
Model of induction of EcR-B1 in the remodeling neurons by glial Myoglanin
Awasaki Nat Neur 2011

7. A schematic representation of axon pruning in MB g neurons
Yu and Schuldiner COiN 2014

8. APF
Disappearance of clustered varicosities in the axon bundle of g neurons
The surface of the lobe is smooth at L3 (A), but it appears eroded at 6 hr APF (B)
cb: cell bodies; ca: calyx (dendrites); p: peduncle; m: medial lobe and axon branch; d: dorsal lobe and axon branch
Awasaki and Ito Current Biology 2004

9. Single optical section are shown
Disappearance of clustered varicosities in the axon bundle of g neurons
Single optical section are shown
Axon branches of g neurons are labeled uniformly at L3 (A), whereas holes of unlabeled regions appear at 6 hr APF (B) (arrowheads). Stars correspond to
unlabeled axon bundle of a'b' neurons.
Genotype: GAL4-201Y / UAS-cGFP
Awasaki and Ito Current Biology 2004

10. Glia cells infiltrating into the mass of MB axons
Awasaki and Ito Current Biology 2004

11. shibire gene is the Drosophila homolog of dynamin, which is involved in cellular membrane functions, including endocytosis, phagocytosis and membrane growth.
Shits protein acts as a dominant-negative at a restrictive temperature.
White Current Biology 2001

12. Effect of targeted disruption of glial function on glial infiltration and on axon pruning
Morphology of glial cells labeled with GFP (green) was abnormal (arrows) and their
processes infiltrate into the lobes neither at 6 (A) nor at 18 hr APF (B).
Awasaki and Ito Current Biology 2004

13. Expression of Drpr (a glial cell corpse engulfment membrane receptor) in the glial processes infiltrating into the MB lobe
Awasaki and Ito Current Biology 2004

14. Effect of targeted expression of EcR-DN in g neurons on glial infiltration
Awasaki and Ito Current Biology 2004

15. Schematic model of the elimination of varicosities by infiltrated glia
(A and B): diagram of the multiple axon branches of g neurons in L3 (A) and early pupa (B) at around 6h APF. (C-G): steps of infiltration and engulfing action of glial processes.
Awasaki and Ito Current Biology 2004

16. Model for the role of glia in axon pruning
Schematic model of the role of glia on developmentally programmed axon pruning
Awasaki Neuron 2006

17. Model for the role of glia in axon pruning
Boulanger BBA 2015

18. Hierarchy of the olfactory nervous system
in insects and mammals
Davis Neuron 2004

19. Is MB larval pruning is necessary for adult memory?
Short Term Memory (STM): forms right after learning, based on transient events,
lasting from a few minutes to a few hours.
Long Term Memory (LTM): forms later with de novo protein synthesis, lasting from several hours to days.

20. Awasaki and Lee after Boulanger at al., Nature Neuroscience 2011

21. Ectopic expression of Hr39 into larval g blocks pruning
GAL4-201Y,UAS-GFP/ +
GAL4-201Y,UAS-GFP/ UAS-Hr39
larval g g
adult g

22. Ectopic expression of Hr39 blocks  neuronal remodellingwt
mutant a b a a’ a’ b b’ b’ g
(adult) g
(larval)
Blocking  pruning effect on short term memory and long term memory?

23. Courtship behavior

24. Memory after courtship conditioning paradigm
Short-term paradigm: 30’ with a mated female
Retraining test (with a mated female) - last few hours (STM)
Long-term paradigm: 5 hours with a mated female
Retraining test (with a mated female) - last for days (LTM)
CI - courtship index - % of time spent in courtship during a 300-s period.
If CIexp = 0, then PI = 1 (complete memory)
If CIexp = CIcont, then PI = 0 (no memory)
CIcont CIexp
CIcont
x 100% =
( 1 -
CIexp )
PI - performance index
x 100%
PI =
McBride et al., Neuron 1999; Kamyshev et al., Learn. Mem. 1999

25. Blocking neuronal remodeling of  neurons impairs STM but not LTM
(ab) a’ b’ a b
(larval) a’ a b b’ g a’ a b b’ g
Blocking neuronal remodeling of  neurons impairs STM but not LTM
Redt-Clouet et al., Eur J Neuroscience 2012

26. • MB larval pruning is necessary for adult STM not for LTM.
Conclusions
• MB larval pruning is necessary for adult STM not for LTM.
• STM and LTM may be two parallel and independent memory systems.
It is possible to get LTM without STM.
sequential model : LRN > STM > LTM
> STM (g)
> LTM (ab)
parallel model :
LRN