Patterning the AP axis Flashcards
Cells with high nodal and active wnt signalling induce what?
The organiser
What is goosecoid activated by?
Both nodal downstream effector (smad2/4)
A wnt signalling/ beta catenin downstream effector
Where is brachyury expressed?
Low levels of nodal
List genes induced in repsonse to high nodal and activated Wnt signalling
Goosecoid, Chordin, Xnot and Xlim
Organiser/node cells differentiate into what type of mesoderm?
Axial
What is the process called in which axial mesoderm cells migrate?
convergent extension
Why do different types of axial mesoderm form eg prechordal mesoderm and notochord?
Siamois/goosecoid are expressed at fractionally different levels in the organiser
In which direction does gastrulation move?
From the posterior end to the anterior end
List the mix of progenitor cells in the organiser
prechordal mesendoderm, prechordal mesoderm, notochord = all form axial mesoderm
Which proteins give cells a posterior identity?
FGF and retinoic acid
Anti-Wnts maintain what?
Anterior identities
Neuralisation of ectoderm and dorsalisation of mesoderm are both mediated by what?
BMP antagonists eg chordin which are secreted by the organiser
List four BMP inhibitors
Chordin, noggin, frizbee and follistatin
Where do BMP antagonists act and what do they induce?
They act on overlying ectoderm to induce neural ectoderm
If BMP signalling is not blocked in the ectoderm what is produced?
Skin
