Lecture 2 - neural plate formation

Question 1

what cells become neural cells?

Answer 1

some ectodermal cells will become ‘induced’ to change their fate

Question 2

key pathway for neural induction

Answer 2

Bone Morphogenesis pathway (BMP)

Question 3

BMP pathway

Answer 3

external cell secreted ligand and responding cell has BMP receptors to activate the signalling cascade leading to phosphorylation to activate transcription factor

Question 4

SMAD158 (transcription factor)

Answer 4

is phosphorylated in signalling cascade where it enters nucleus and bonds to promoters for different genes to either activate or inhibit transcription

Question 5

Chordin and noggin

Answer 5

proteins that antagonise BMPs to prevent them from binding to BMP receptors. Binding to BMP affinity is greater than BMP receptors so there is no more BMP for signalling.

Question 6

3 germ layers

Answer 6

1. ectoderm (top)
2. mesoderm (middle)
3. endoderm (bottom)
   - these germ layers make cells more restricted

Question 7

organiser cells

Answer 7

small group of cells different to the rest of mesoderm - dorsal mesoderm cells

Question 8

ectoderm cells close to organiser cells

Answer 8

generates neural tissue that end up giving rise to neural stem cells

Question 9

ectoderm cells further away from dorsal mesoderm cells

Answer 9

give rise to skin cells

Question 10

protein secreted by dorsal mesoderm cells

Answer 10

is an antagonist to BMP signalling (chordin, noggin and follistatin)

Question 11

ectoderm cells where BMP signalling pathway is inhibited

Answer 11

their transcriptional factor is altered and start generating neural stem cells

Question 12

before formation of organiser cells

Answer 12

all ectoderm cells has phosphorylated SMAD158

Question 13

Low smad 1 and low smad 8

Answer 13

means there is no transcription of GATA1 for epidermalisation

Question 14

SOX2 gene

Answer 14

determines the neural cell

Question 15

where is neural plate induced?

Answer 15

in the ectoderm where BMP is inhibited

Question 16

what is neural plate

Answer 16

plate of cells that are all expressing neural stem cells and all expressing SOX2

Question 17

evidence to prove this

Answer 17

doing fate maps seeing where different dyes end up when injected into certain regions

Question 18

conversion extension

Answer 18

long thin rod of mesoderm ends up under the midline of neural tube

Question 19

spemann and mangold ‘organiser graft’

Answer 19

• added dorsal mesoderm cells to both ends of the mesoderm and neural plate on both sides resulting in two neural plates.
• used grafted tissue from a newt that had different pigmentation to distinguish which parts of tissue come from donor and host.