Cell determination Flashcards
What results from cells with activated proneural genes
Become neuroblasts - Competent to become neurons
What is seen in proneural mutants
No cells become neurons
What happens in a Notch mutant
More neurons are formed
What is lateral inhibition
Involves transmission of an inhibitory signal between a pair or cluster of cells to prevent the cells receiving that signal from becoming a particular fate
How does the Delta Notch signalling pathway occur
Upregulation of Notch signalling occurs in one cell
This causes upregulation of the transcription factor - suppressor of hairless
This causes the upregulation of the transcription factor enhancer of split
This acts on the promoter or Achaete-scute to downregulate its production
This reduces delta production in that cell
Opposite effect is seen in the adjacent cell (les notch signalling -> increased delta)
How do cells acquire neuronal cell fates via delta notch signalling
Achaete-scute needed in particularly high levels to turn on activation of other TF’s which promote neuronal identity
What dictates neural diffusion
Transcription factor code - as cells differentiate they move laterally
Where do some daughter cells migrate to if they differentiate into mature neurons
The mantle zone
Where do daughter cells of progenitors that don’t differentiate stay
Stay in the ventricular zone - luminal surface of the neural tube epithelium - remain as a progenitor cell
What is the shape of the progenitor cells that dont differentiate
Radial glia - provide a pool of undifferentiated cells that are used to build up the nervous system over time in embryogenesis
Where are radial glia located
Big cell body in the ventricular zone and send long processes to the pial surface - outer mantle
How do radial glia divide
Asymmetrically - one remains as a radial glia - the other uses the scaffold provided by its sister to migrate away from the ventricular zone and will differentiate into a neuron
What is the importance of the asymmetrical division of neural progenitors
It occurs throughout the brain and spinal cord - converting one cell thick neural tube into the multiple layered cortices of the spinal cord and cerebrum/cerebellum
