Cell death in the developing NS

Question 1

In C.elegans what type of cells do cells prevented from apoptosis normally become and what does this suggest

Answer 1

Neurons - suggests cell death acts to limit the number of neurons present in the mature C.elegans

Question 2

What family of genes are responsible for apoptosis in C.elegans and what arises from KO of these genes

Answer 2

ced
ced-3/4 KO - excess numbers of adult cells
ced-9 massive cell death

Question 3

What is the role of ced-9

Answer 3

Protects cell from apoptosis

Question 4

What is the role of ced -4/3

Answer 4

Promotes apoptosis

Question 5

What is the name of the protein coded for by the ced-3 gene

Answer 5

Caspase - proteolytic enzyme

Question 6

What percentage of neurons are lost during development

Answer 6

50

Question 7

What are the two triggers for developmental apoptosis

Answer 7

1. Lack of neurotrophic factors present

2. Absence of depolarising stimulus

Question 8

What role do neurotrophins have in apoptosis (and their receptors)

Answer 8

Reduction in neurotrophins from sympathetic ganglia - have high P75-NTR (low TKC) - activates P75 - NTR results in a cell death signal for apoptosis

Question 9

What is neurotrophin release dependent on

Answer 9

Calcium release - triggered by depolarising or ligand binding - more efficient synapse have more stimulated release - more binding and uptake by membrane recycling thus have a greater presynaptic effect - more target tissue results in more release of neurotrophins