Lect. 13 - nervous system induction

Question 1

primitive nodes’ role in forming notochord

Answer 1

provides source of cells that will form the notochord

Question 2

Describe formation of the notochord

Answer 2

cell precursors migrate anteriorly and then left behind as rodlike aggregation as primitive streak regresses; notochordal cells fuse w/ flanking endodermal cells and from a canal; the cells separate and aggregate to form notochord

Question 3

what is the relationship of Nodal to the establishment of the anteroposterior axis

Answer 3

expression of nodal in post. epiblast and blocking of nodal in anterior epiblast (by lefty 1 and cer 1) results in the establishment of the axis

Question 4

how is wnt3 related to nodal?

Answer 4

Wnt3 induces the expression of nodal

Question 5

what signaling molecules are involved in the inhibition of posterior structures?

Answer 5

cerebrus-like and DKK-1

Question 6

what signaling molecules from the primitive node are involved in neural induction?

Answer 6

noggin and chordin

Question 7

nodal is a signaling molecules produced by the primitive node; what is its role in the induction?

Answer 7

it induces the primitive streak and helps establish left-right symmetry

Question 8

what is the source and role of Cerebrus-like and DKK-1 in development of ant.-post. axis?

Answer 8

anterior visceral endoderm; inhibits development of posterior structures

Question 9

what are the origin and effects of TFs goosecoid and brachyury w/ regard to the early primitive streak?

Answer 9

goosecoid: primitive node -activates chordin and noggin
brachyury: primitive streak - notochord fomation; normal movements of cells through primitive streak

Question 10

what genes are targeted by goosecoid?

Answer 10

chordin and noggin

Question 11

what are the effects of Foxa-2 on the early primitive streak stage?

Answer 11

establishment of the primitive node; initiates notochord function; establishes midline strucutres cranial to node

Question 12

in the late primitive streak stage, what signaling molecules is necessary for normal head fromation?

Answer 12

cerebrus-related 1

Question 13

in the late primitve streak stage, what signaling molecules are needed for neural induction, and what is their origin?

Answer 13

noggin, chordin, and shh; origin: notochord

Question 14

determination

Answer 14

a process by which a cell or part of an embryo becomes restricted to a given developmental pathway. The point at which a cell becomes committed to a specific cell line.

Question 15

differentiation:

Answer 15

a complex of changes involved in the progressive specialization of structure and function; often resulting in the formation of luxury molecules

Question 16

what is the first sign of asymmetry in early development?

Answer 16

the beating of cilia around the primitive node which results in a directional current and expression of TGF-beta molecules

Question 17

what role does nodal play in asymmetry?

Answer 17

swept to left side of node; stimulates multiple gene expression pathways via Pitx-2

Question 18

what role does lefty-1 play in asymmetry?

Answer 18

expressed on left side; blocks diffusion of molecules to the right side.