Neural Patterning

Question 1

What is neural patterning?

Answer 1

formation of the different regions of the nervous systems

Question 2

What are the neural patterning types?

Answer 2

anterior-posterior patterning
dorsal-ventral patterning

Question 3

What are the general principles of neural patterning?

Answer 3

1. The molecular mechanisms of patterning are conserved among different species
2. Gradients of soluble proteins and patterns of transcription factor expression control pattern formation
3. Certain factors can have different developmental effects depending on time and location of their action (BMP4)
4. Generally, anterior-posterior patterning happens before dorsal-ventral patterning

Question 4

What are morphogens?

Answer 4

Morphogens are factors that usually act in a gradient manner to determine the fate of cells

Question 5

FGF?

Answer 5

it is a posteriorizing signal that is high in concentration at the tail; induces structures

Question 6

wingless/wnt proteins?

Answer 6

it is a posteriorizing signal that is high in concentration at the tail; induces structures

Question 7

BMP?

Answer 7

it is a dorsalizing signal; induces structures on dorsal side (spine?)

Question 8

hedgehog/sonic hedgehog

Answer 8

it is a ventralizing signal

Question 9

Hox gene?

Answer 9

transcription factors that regulate expression of other genes

Question 10

What does the anterior mesoderm become?

Answer 10

Head

Question 11

What does the posterior mesoderm become?

Answer 11

trunk and tail

Question 12

2 step induction method?

Answer 12

1. mesoderm releases factors and starts to move underneath the ectoderm
2. anterior neural forms first; posterior neural 2nd

Question 13

What factors are more concentrated at the posterior end?

Answer 13

FGF, Wnt, and RA (retinoic acid)

Question 14

Where was hox genes discovered?

Answer 14

drosophila

Question 15

Principles of Hox gene organization and expression

Answer 15

1. the lower the hox gene number, the more 3’ location on the chromosome
2. the lower the number, the earlier in development the expression begins
3. the lower the number, the more anterior expression begins

Question 16

The regulated expression of hox genes provides a positional code for patterning in ______ and _____ ____

Answer 16

hindbrain; spinal cord

Question 17

The hindbrain is segmented into what?

Answer 17

8 rhombomeres that correlate with expression boundaries of hox genes

Question 18

What is main dorsalizing signals? What does it induce?

Answer 18

BMP-4 and -7 induce roof plate

Question 19

What is main ventralizing signal? What does it induce?

Answer 19

sonic hedgehog(shh) induces floor plate

Question 20

What produces DV inductive signals?

Answer 20

BMP is made from ectoderm then roof plate; shh is made from notochord then floor plate

Question 21

gradients of __________ and patterns of _________________ control pattern formation

Answer 21

soluble proteins; transcription factor expression

Question 22

What happens first AP patterning or DS patterning?

Answer 22

anterior-posterior