lecture 7-neurogenesis Flashcards
describe the Shh signalling pathway
sonic hedgehog is the signal that activates the signalling pathway in cells
Gli transcription factors are the primary effectors , these promote the expression of the target genes
what are the three types of cell progenitor cells give rise to in the nervous system
neurons
glia
astrocytes
where to regenerated progenitor cells stay
next to the lumen in the ventricular zone
why does the neural tube look wider than it actually is
when progenitor cells go through division, the nucleus migrates to different points
at which point of progenitor cell division is the nucleus closest to the lumen
m phase and cytokinesis
describe symmetrical division of neuroepithelial cells
2 identical daughter cells produced
describe asymmetrical division of neuroepithelial cells
shape change to radial glial cells
divide, giving rise to one normal daughter cell and a second neuronal cell
this neuronal cell uses its sister to migrate along to get away from the ventricular zone
why do neuroepithelial cells change
to radial glial cells
as they have longer processes
how does cell division plane determine cell fate
if the cell divides along the meridian, 2 identical daughter cells are formed
if the cell divides along the equator 2 different cells are produced
why does neurogenesis occur
as asymmetrical cell division leads to daughter cells with different levels of notch signalling
describe delta notch signalling
cell 1 produces more delta signal which stops cell 2 from making delta(due to achaete-scute becoming inhibited)
what do high levels of achaete-scute lead to
the turning on of TFs telling the cell to become a neuron therefore it will become a neuron
what change to notch signalling causes neuronal cell fate
decreased notch signalling
what is the evidence in drosophila for notch signalling in neurogenesis
in achaete-scute mutants no cells become neurons
in notch mutants more neurons form
which birth defect does no Shh lead to
no seperation in the brain and only 1 eye
