L14: Xenopus Gastrulation Flashcards
What is the outcome of gastrulation?
Three primordial layers: ectoderm, mesoderm, endoderm
What are 5 types of cellular movements in gastrulation?
- Invagination
- Ingression
- Involution
- Delamination
- Epiboly
Invagination
clefting in
Ingression
individual EMT
involution
single layer wrapping inside
delamination
group EMT in one layer
Epiboly
3D involution
Why study frog?
- Fast growth
- Well documented
- Microsurgery
- large and abundant embryo
In how many hours after fertilization does gastrulation happen in xenopus?
10 hours
How many cells in gastrula?
30,000
What is morpholine?
A structure similar to de/oxyribose sugar in DNA and RNA that it replaces
Function of morpholino oligo
It makes translational complex unable to form by binding to start codon. since it says in the system for a long time, it enables long term, specific mis-expression of genes than siRNA
Why is the blastocoel gap important?
- it prevents interactions between the roof and floor
- Provides space for cell migration in gastrulation
How is blastocoel roof help together?
cell-cell adhesion: tight and gap junctions
What happens to blastocoel roof if EP-cadherin is negated?
BTR falls apart
What are the sides in blastula?
Animal and vegetal
Where is the dorsal lip of the blastopore?
in the vegetal side
Draw the transition due to epiboly in gastrulation in midsagital cut. (Label the blastopore lip, gut, mesoderm, ectoderm, endoderm)
How does fibronectin form fibril?
- Comes in dimer form.
- Binds to cell surface with Integrin a5ß1
- Expands around the cell membrane
- Forms fibril through self-polymerization
What physical changes take place in ectoderm before gastrulation?
- Superficial layer extends
- Radial intercalation in deep layer
What is required for intercalation?
- A5ß1integrin
- Fibronectic network
- C3 and C3r
Without FN, what does not happen properly?
cell polarity, shown by the location of mitotic fibrils
What are the two functions of C3?
- intercalation
- cell protrusion towards superficial cells
What is the mechanism of protrusion due to c3?
unknown
What is the PDGF pathway?
- PDGF > PI3K
- > Cdb42 > filopodia
- > Rac1 > lamellipodia
- > Rho > actin, stress fibres, adhesions
What must be located between the mesoendoderm and ectoderm for there to be directional movement towards animal side?
FN with PDGF gradient
Removing which stuff means no movement? (5 things)
- FN
- PDGF
- PDGFR
- PI3-K
What are two types of PDGF
truncated and long form
Which PDGF is required and why?
long form because truncated doesnt bind to FN. Both bind to PDGFR
What do bottle cells do?
Push the meseoenderm towards the outer edge. keeping the curvature
Why does the cell perform epiboly?
to create the mesoderm.
What is the importance of interacalation?
pushes the cells to become mesoderm through epiboly.
