Elegans Development

Question 1

What does necessary and sufficient entail?

Answer 1

• Necessary: If we remove X we don’t get Y

- Sufficient: If we add X we get Y

Question 2

What are 3 core mechanisms for development determination?

Answer 2

• Segregation of determinants
• Induction, interaction between different cells
• Lateral inhibition, interactions between identical cell types

Question 3

How many founder cells are there in C elegans? And how many produce only one tissue type?

Answer 3

• 6 founders, 3 dedicated

Question 4

What are the daughters of P0?

Answer 4

• AB develops to hypodermis, neurons, pharynx, ..

- All cell types develop from P1

Question 5

What are the daughters of AB?

Answer 5

• ABa forms hypodermis, neurons, posterior pharynx

- ABp forms hypodermis, neurons, muscle

Question 6

What are the daughters of P1?

Answer 6

• EMS forms MS which forms muscles and anterior pharynx and E which forms gut
• P2 forms C which forms muscles and hypodermis and P3

Question 7

How does the posterior pharynx develop?

Answer 7

• Segregation of GLP-1 Notch receptor to AB

- GLP-1 ligand provided by neighboring MS

Question 8

How does ABp differentiate from ABa? *

Answer 8

• Both get GLP-1 Notch receptor from AB
• Both get signal from MS in form of ligand (signaling molecule)
• Contact with P2 in ABp provides APX-1 Delta ligand

Question 9

How does the EMS lineage differentiate?

Answer 9

• SKN-1 and PIE-1 segregate with P1
• POP-1 segregates to EMS whilst PIE-1 segregates to P2
• SKN-1 segregates to both EMS and P2 but is suppressed in P2 by PIE-1
• PIE-1 transcribes MOM-2 which suppresses POP-1 in neighboring E, allowing gut development
• In MS POP-1 and SKN-1 allow formation of pharynx and muscles

Question 10

What is the anchor cell’s role in vulva development?

Answer 10

• Lateral inhibition between 2 cells creates an anchor cell and ventral uterine precursor (VPCs)
• Influences development of 6 VPCs

Question 11

What do the different VPCs develop into?

Answer 11

• 1 and 2 form vulva

- 3 forms hypodermis and epidermis

Question 12

How do morphogens contribute to vulva development?

Answer 12

• AC generates LIN-3 creating a gradient which forms 1,2,3 grade VPCs
• LET-23 receptor

Question 13

How does sequential signaling contribute to VPC development?

Answer 13

• When LET-23 is only present in grade 1, grade 2 still forms, with grade 3 standard
• grade 1 produces LIN-12 delta ligand
• LIN-12 notch receptor inhibited by higher LET-23
• grade 2 received LIN-12 delta ligand
• LIN-12 notch receptor not inhibited

Question 14

How are spaced patterns of equivalent cells formed?

Answer 14

• Lateral inhibition

Question 15

How are C.e glia and neurons differitated?

Answer 15

• Lateral inhibition causes a cell to separate from 2D layer and develop to neuroblast, on top layers of neural progenitors form (GMCs)
• Occurs via segregation and depletion of different GMC factors to create different GMCs