lec 5. anterior vs. posterior

Question 1

Otx2 and Gbx

Answer 1

Otx2 - expressed in anterior 1/3rd of neural tube, predicting forebrain
Gbx - expressed in posterior 2/3rds of neural tube, predicting hindbrain

Question 2

2 models for AP regionalisation

Answer 2

1) organiser differentiates into AE, PM, ad NC. AE and PM make anterior cells brain like. NC makes posterior cells spinal cord
2) initially, everything is brain-like under AE and PM, then NC transforms posterior cells into spinal cord

Question 3

axial mesoderm

Answer 3

the organiser differentiates into anterior endoderm (AE) prechordal mesoderm (PM), and notochord (NC) which extend under the midline of the newly induced neural plate

Question 4

signals that come from prechordal mesoderm and notochord

Answer 4

AE+PM - retinoic acid and Wnt antagonists (anterior -> brain)
NC - retinoic acid and Wnt (posterior -> spine)

Question 5

french flag model in AP segmentation

Answer 5

retinoic acid, expressed by the axial mesoderm under the neural plate, in different concentrations acts as a morphogen to induce differential expression of hox genes

Question 6

hox genes

Answer 6

specify the regions of the body play. different ones are induced by different concentrations of hox genes.