C. Elegans Development Flashcards
What are two reasons why a daughter cell may go on to express different genes and be something different from the mother cell?
- Intrinsic - when the mother cell divides into two daughter cells and one contains different things than the other which will lead it to be different
2 Extrinsic - Signalling between cells and tissues causing cells to become different things so the daughter could respond to a signal and become different
What does the zygote (Po) of c. elegans split into in the first cell division?
AB and P1
What does the AB cell split into?
Aba and ABp
What does P1 split into?
EMS and P2
What do ABa and Abp go on to become?
The ectoderm
What happens to make AB and P1 different when P0 is divided?
Differential cleavage - one has different contents than another
What happens to make ABa and ABp different when AB divides?
Signalling makes them different
What defines the posterior end in the c.elegans?
The sperm entry
What are P-granules?
Dots in the c.elegans embryo that autoflourescence and differentially go to the posterior end - a mixture of mRNAS and proteins
Where do the P-granules move toward?
The point of sperm entry in the posterior end of the cell
What happens to P1 during cell divisions?
It becomes P2, P3, P4 and becomes more localised into the posterior end of the cell and then goes on to make the germline
How could you prove that it is the point of sperm entry that causes the end to become posterior?
If you destroy the sperm centrosome with a laser then the cell losing its asymmetry
What is PIE-1?
A maternal effect gene
What is the phenotype of PIE-1 mutants?
They have a posterior end defective where the P1 cell becomes two EMS cells instead of a P1 and P2
How are P granules distrubuted during cell divisions?
They are segregated to P1 then to P2 (degraded in EMS)
How are P granules and PIE-1 linked?
In pie-1 mutants two EMS cells are produced; this means that PIE-1 must be involved in making P2 different from EMS
what happens to PIE-1 through the cell divisions?
It becomes more localised in P1-2-3-4
What happens to PIE1 in cells that are not P?
It gets degraded
What does the PIE1 gene encoded?
A transcriptional repressor protein
what are PAR genes?
They encode things that physically move the PIE-1 transcriptional repressors into the cells
What happens if you exchange ABa and ABp?
nothing they are interchangeable as they sense their position
What makes P1 different from AB?
Differential segregation of P-granules
What makes P1 different from EMS?
Pie-1 and Pgranules in P1 make it different from EMS
What receptor do both ABp and ABa express?
GLP-1
What receptor does EMS make?
MOM-5
What ligand does P2 make and what is it involved in?
P2 makes ABX-1 which is the ligand for GLP-1 and causes it to be ABp to be different from ABa
What leads to E being different from MS?
P2 produces a ligand called MOM2 which is the ligand for MOM5 in EMS and causes E to be different from MS
