Drosophila medulla neuroblast termination via apoptosis, differentiation and gliogenic switch is scheduled by the depletion of the neuroepithelial stem cell pool

The brain is consisted of diverse neurons arising from a limited number of neural stem cells. Drosophila neural stem cells called neuroblasts (NBs) produces specific neural lineages of various lineage sizes depending on their location in the brain. In the Drosophila visual processing centre - the optic lobes (OLs), medulla NBs derived from the neuroepithelium (NE) give rise to neurons and glia cells of the medulla cortex. The timing and the mechanisms responsible for the cessation of medulla NBs are so far not known. In this study, we show that the termination of medulla NBs during early pupal development is determined by the exhaustion of the NE stem cell pool. Hence, altering NE-NB transition during larval neurogenesis disrupts the timely termination of medulla NBs. Medulla NBs terminate neurogenesis via a combination of apoptosis, terminal symmetric division via Prospero, and a switch to gliogenesis via Glial Cell Missing (Gcm), however, these processes occur independently of each ot..., Fly stocks and husbandry
The fly strains used were detailed in the extended Materials and Methods in the paper. Fly stocks were reared on standard media at 25oC. For larval dissection, brains were dissected at wandering L3 stages (approximately 120h ALH). For pupal dissection, white pupae were selected and allowed to age to the desired stages.
 Knockdown and overexpression experiments using eyR16F10-GAL4 were moved to 29oC after overnight embryo collection until dissection. Experiments using tub-GAL80ts;eyR16F10-GAL4, embryos were reared at 25oC for one day, larvae were then moved to repressive 18oC for 5 days to inhibit GAL4 activity, and transferred to permissive 29oC to induce GAL4-mediated transgene expression for 2 days prior to dissection. Knockdown and overexpression flip-out clones were induced at 24h ALH at 37oC for 10 min and then allowed to develop at 29oC until dissection except for pros RNAi clones that were let developed at 25oC to allow a mild knockdown of pros. FRT42D a..., , Source data associated with the paper \"*Drosophila* medulla neuroblast termination via apoptosis, differentiation and gliogenic switch is scheduled by the depletion of the neuroepithelial stem cell pool\" by Nguyen and Cheng, 2014.

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Abbreviations:
NB: neuroblast
APF: after pupal formation
ALH: after larval hatching
NE: neuroepithelial
tTF: temporal transcription factor
Slp: sloppy-paired
mChe: mCherry
med12: mediator 12
Ey: eyeless
Red: RedStinger
EcR: ecdysone receptor
DN: dominant negative
Dpn: Deadpan
n: notch...