Recap 2nd year Flashcards
What molecule is important in the prevention of neural induction and how can this be shown experimentally
BMP2, 4 and 7 found in the animal cap in Xenopus oocytes
mRNA for a truncated BMP receptor into the animal cap leads to the development of neurons instead of epidermis
Which molecules in the involuting mesoderm at the blastopore bind to BMP receptors in the neural plate, inhibiting their action (in Xenopus)
Follistatin, Cerberus, Noggin, Chordin - neural induction in this area.
What is the invertebrate drosophila gene for BMP2/4
dpp (decapentaplegic)
What is the drosophila homologue of chordin
Short gastrulation (sog)
On what side of the embryo is the neural plate found
Dorsal
What is the molecular pathway for the differentiation of a dorsal ectodermal cell to a neural plate cell.
BMP antagonism induces the activity of smad7, which inhibits smad1.
Smad 7 and low Smad 1 leads to SoxD, Xlpou2 (neuralising TFs) for cells to produce neurogenin, then neuroD which induces neural differentiation
Which transcription factor in the organiser induces the expression of chrodin, noggin etc
Goosecoid, Gsc
What types of cell movement does axial mesoderm undergo as gastrulation proceeds
Involutes - an epithelial sheet rolls inward to form an underlying layer
Intercalates - rows of cells move between one another, creating an array of cells that is longer (in one or more dimensions) but thinner.
Convergent extension - Rows of cells intercalate, but the intercalation is highly directional.
What happens to the organiser after neural plate induction
It begins to differentiate into axial mesoderm - involuting, intercalating and undergoing convergent extension
What is invagination
A sheet of cells (epithelial sheet) bends inwards
What is ingression
Individual cells leave the epithelial sheet and become freely migrating mesenchyme cells
What is an epiboly
A sheet of cells that spreads by thinning
What is the importance of the differentiation and movement of the axial mesoderm
Gives rise to the regionalisation of the AP axis
What are the domain that make up the forebrain, midbrain and hindbrain
Telencephalon, diencephalon = Forebrain
Mesencephalon = midbrain
Metencephalon + myelencephalon = hindbrain
What can be said about the character of the early induced neural plate
Expressing markers that are later confined to the forebrain - Anterior in character
What markers are found in the anterior prechordal mesoderm
Cerberus and other BMP/Wnt antagonists,
What differs in the notochord and late node compared to the prechordal mesoderm
Provide signals that promote proliferation and growth of neural cells and their posteriorisation
What markers are expressed in the notochord/ late organiser
FGF, Wnt, RA
What is the role of the specialised border at the edge f the neural plate/ectoderm
Crucial for neural crest formation as well as roof plate formation and dorsal neural tube patterning
What is the role of BMPs in relation to neural crest cells
Working with Wnt and FGF signalling - initiate a cascade of events to give rise to a highly potent and proliferative set of neural crest cells
What is the role of the notochord in patterning the ventral neural tube
The secreted ligand Shh is expressed in the notochord and then in the floor plate - Acts as a morphogen to induce different progenitor cells along the dorso-ventral axis of the future spinal cord
What evidence is there that Shh is a morphogen
Immunohistochemistry shows Shh protein in a gradient, emanating away from its source cells
What is the result of Shh morphogen signalling
Different transcription factors appear in bands of progenitor cells along the d-v axis.
What happens to progenitor cells along the d-v axis as they differentiate q
They move laterally
