L8 - Binary Decisions Flashcards
What is the BMP/WNT and Shh gradient transformed into
Gli-activator// Gli repressor gradient within the nucleus of cells
What occurs as cells differentiate
The move laterally away from the lumen (ventricular zone) but SOME are retained at the VZ
What can radial glia also be thought of as
Neural stem cells
What do the radial glia provide
A pool of undifferentiated cells that are used to build up the nervous system during embryogenesis
What can be said about the nuclei of the radial glia
What does this mean
Undergoing INTERKINETIC MIGRATION
That they have connection with the lateral surface during some periods of the cell cycle - this attachment is then lost during another phase before it is reformed
What is the connection of the cell during each of the phases of the cell cycle
G1 attached S attached G2 attached M - attachement to the lateral surface is lost G1 - attchemet is reformed
How do ealry neuroepithelia differentitate
Symmetrically giving rise to two identical daughter cells
Describe the asymetric division of the radial glial cells
1 daughter is like mother - also a radial glia
1 uses the mother as a scaffold to migrate laterally and become a differentiated neurone
How do cells divide asymmetrically
Unequal distribution of cytoplasmic determinants
What is the signalling pathway which separates cells from an equivilance groups
Delta notch signalling pathway `
What is the receptor in notch signalling
NOTCH
What form in which there is competency of cells to become neruones
Proneural clusters
What are proneural mutants
Occur where there is no development of any neurones
What are proneural mutants also known as
Achatet-scute mutants
What are neurogenic mutants
Too many neurones developing
What are neurogenic mutants also known as
Notch -1- mutants (absence)
What does notch regulate
Lateral inhibition
What is lateral inhibition
Special kind of induction - used to separate cells within an equivliance group
Involves the transmission of an inhibitory signal between a pair of cluster cells to prevent cells recivieing the signal to adopt a particular cell fate
Describe the mechanisms of notch
Initially both cells equally making delta and reciiveing (through notch) the inhibitory signal
Introduction of change/bias so one cell begins to make more inhibitory signal - it becomes more inhibited and makes less of the signal
What must occur in order for the change to be stabilised
Cell must be prevented from being able to continuously send the inhibitory signal
What is the affect of achete scute proteins on the neighbouring cell
Causes inhibition of hairless
Leads to enhancer of split proteins
Inhibiton of achete scute proteins
What occurs in the cell where there are the most achete scute proteins (least inhibited)
Expression of BHLH proteins
Cell becomes a neuronal precursor
What occurs in the cell where there is most inhibition of the achatete scute proteins
Cell becomes a supporting cell
What is notch throught to be involved
Many bilateral cell fate decisions
Describe the pathway a proneural cell would take in order to become
ASTROCYTE
OLIGODENDROCYTE
NEURONES
i) Multi potent progenitor –> Glia progenitor –> astrocyte
ii) Mutli potent progenitor –> Glial progenitor –> oligodendrocyte
iii) Multi potent progenitor –> Committed neural precurrsor –> neurones
