Cell Fate and Embryonic Induction Flashcards
Difference between preformation and epigenesis
Correctly position in fertilised egg / added progressively during development
Cleavage divisions in ascidians
Holoblastic
Yellow cytoplasm of ascidian always found in
Muscle cells of the larval tail
macho-1
A putative zinc-finger TF, sufficient and necessary for primary muscle formation
Maternal macho-1 is localised in _______ cytoplasm at ___ and ____ cell stage
in yellow cytoplasm at 16 and 32 cell stage
Embryonic regulation
Ability of embryo to develop normally when portions are removed or rearranged
Embryonic induction
Process whereby cell-cell signalling affects development of responding cells
Competence
Ability of cell/tissue to respond to an inductive signal
Mesoderm is induced in the ______ fragment by the ______ fragment
animal, vegetal
Which proteins are good candidates for mesoderm-inducing signal?
Nodal and GDF3 in TGFb families
Xenopus Nodal RNA is localised to _______ hemisphere of _______
Localised to vegetal hemisphere of blastula
Inhibition of nodal signalling
Blocks mesoderm formation
Nodal induces expression of
TF brachyury and several members of the FGF family
STK
Serine/thereonine kinase in cytoplasmic kinase domain of c.s. receptor for TGFb ligand
Tyrosine kinase is in the ______ domain of ____ receptor for ____ ligand
In cytoplasmic kinase domain of c.s. receptor for FGF ligand
TGFb ligand becomes ______ that binds to extracellular domain of ________
Dimer, type 1 and type 2 receptors
Activated type 1 receptors
Phosphorylate smad2
Smad 2: Smad 4 complex
Migrates into nucleus where it interacts with co-transcription factors and binds to cis-regulatory elements
Why is nodal signalling an auto-regulatory loop?
TGFb + FGF signals positively regulate transcription of brachyury which encodes a T-box transcription that positive regulates fgf4 and fgf8
At early stages, neural tube at ventral half divides into:
- Floor plate cells at ventral midline above notochord
- Motor neurones
- Interneurons
Shh is both sufficient and necessary for formation of
Ventral neural tube sub-types
From low to high concentration of Shh
V0, V1, V2, Motor Neurons, V3 and finally floor plate
Shh is a _____, ____ secreted from _____ plate
morphogen -> BMP secreted from roof plate
Shh -> mesodermal cell type
Sclerotome
Nodal induces _______ when added to _______ caps
Mesoderm, animal
