What does necessary and sufficient entail?
- Necessary: If we remove X we don’t get Y
- Sufficient: If we add X we get Y
What are 3 core mechanisms for development determination?
- Segregation of determinants
- Induction, interaction between different cells
- Lateral inhibition, interactions between identical cell types
How many founder cells are there in C elegans? And how many produce only one tissue type?
- 6 founders, 3 dedicated
What are the daughters of P0?
- AB develops to hypodermis, neurons, pharynx, ..
- All cell types develop from P1
What are the daughters of AB?
- ABa forms hypodermis, neurons, posterior pharynx
- ABp forms hypodermis, neurons, muscle
What are the daughters of P1?
- EMS forms MS which forms muscles and anterior pharynx and E which forms gut
- P2 forms C which forms muscles and hypodermis and P3
How does the posterior pharynx develop?
- Segregation of GLP-1 Notch receptor to AB
- GLP-1 ligand provided by neighboring MS
How does ABp differentiate from ABa? *
- 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
How does the EMS lineage differentiate?
- 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
What is the anchor cell’s role in vulva development?
- Lateral inhibition between 2 cells creates an anchor cell and ventral uterine precursor (VPCs)
- Influences development of 6 VPCs
What do the different VPCs develop into?
- 1 and 2 form vulva
- 3 forms hypodermis and epidermis
How do morphogens contribute to vulva development?
- AC generates LIN-3 creating a gradient which forms 1,2,3 grade VPCs
- LET-23 receptor
How does sequential signaling contribute to VPC development?
- 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
How are spaced patterns of equivalent cells formed?
- Lateral inhibition
How are C.e glia and neurons differitated?
- 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
