L8 - Binary Decisions

Question 1

What is the BMP/WNT and Shh gradient transformed into

Answer 1

Gli-activator// Gli repressor gradient within the nucleus of cells

Question 2

What occurs as cells differentiate

Answer 2

The move laterally away from the lumen (ventricular zone) but SOME are retained at the VZ

Question 3

What can radial glia also be thought of as

Answer 3

Neural stem cells

Question 4

What do the radial glia provide

Answer 4

A pool of undifferentiated cells that are used to build up the nervous system during embryogenesis

Question 5

What can be said about the nuclei of the radial glia

What does this mean

Answer 5

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

Question 6

What is the connection of the cell during each of the phases of the cell cycle

Answer 6

G1 attached 
S attached 
G2 attached 
M - attachement to the lateral surface is lost 
G1 - attchemet is reformed

Question 7

How do ealry neuroepithelia differentitate

Answer 7

Symmetrically giving rise to two identical daughter cells

Question 8

Describe the asymetric division of the radial glial cells

Answer 8

1 daughter is like mother - also a radial glia

1 uses the mother as a scaffold to migrate laterally and become a differentiated neurone

Question 9

How do cells divide asymmetrically

Answer 9

Unequal distribution of cytoplasmic determinants

Question 10

What is the signalling pathway which separates cells from an equivilance groups

Answer 10

Delta notch signalling pathway `

Question 11

What is the receptor in notch signalling

Answer 11

NOTCH

Question 12

What form in which there is competency of cells to become neruones

Answer 12

Proneural clusters

Question 13

What are proneural mutants

Answer 13

Occur where there is no development of any neurones

Question 14

What are proneural mutants also known as

Answer 14

Achatet-scute mutants

Question 15

What are neurogenic mutants

Answer 15

Too many neurones developing

Question 16

What are neurogenic mutants also known as

Answer 16

Notch -1- mutants (absence)

Question 17

What does notch regulate

Answer 17

Lateral inhibition

Question 18

What is lateral inhibition

Answer 18

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

Question 19

Describe the mechanisms of notch

Answer 19

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

Question 20

What must occur in order for the change to be stabilised

Answer 20

Cell must be prevented from being able to continuously send the inhibitory signal

Question 21

What is the affect of achete scute proteins on the neighbouring cell

Answer 21

Causes inhibition of hairless
Leads to enhancer of split proteins
Inhibiton of achete scute proteins

Question 22

What occurs in the cell where there are the most achete scute proteins (least inhibited)

Answer 22

Expression of BHLH proteins

Cell becomes a neuronal precursor

Question 23

What occurs in the cell where there is most inhibition of the achatete scute proteins

Answer 23

Cell becomes a supporting cell

Question 24

What is notch throught to be involved

Answer 24

Many bilateral cell fate decisions

Question 25

Describe the pathway a proneural cell would take in order to become
ASTROCYTE
OLIGODENDROCYTE
NEURONES

Answer 25

i) Multi potent progenitor –> Glia progenitor –> astrocyte
ii) Mutli potent progenitor –> Glial progenitor –> oligodendrocyte
iii) Multi potent progenitor –> Committed neural precurrsor –> neurones