Lecture 27 - Early Axial Pattern

Question 1

Which specific gene type is a major regulator of asymmetric morphogenesis?

A. NODAL
B. Pitx
C. Bone morphogenetic proteins (BMPs)
D. Fibroblast growth factor (FGF)

Answer 1

B.

Question 2

The secreted signaling molecule, ______, is first detected in a symmetric fashion in node, but then becomes located specifically on the left side of the node and in the left lateral plate mesoderm.

A. NODAL
B. Pitx
C. Bone morphogenetic proteins (BMPs)
D. Fibroblast growth factor (FGF)

Answer 2

A

Question 3

The activation of ______ signaling promotes epidermal fate and suppresses neural fate.

A. NODAL
B. Pitx
C. Bone morphogenetic proteins (BMPs)
D. Fibroblast growth factor (FGF)

Answer 3

C

Question 4

Antagonists of BMP are what two molecules? (Hint: produced by the node and the notochord)

Answer 4

1. Noggin

2. Chordin

Question 5

Which is NOT initially present in posterior (caudal) regions of the gastrulating embryo?

A. FGFs
B. Wnts
C. Dickkopf
D. RA

Answer 5

C. Dickkopf, which inhibits Wnt, is produced by the anterior visceral endoderm (AVE) anterior to the primitive streak.

Question 6

Substantial evidence supports a role for ______ proteins in the programming of neural identity within posterior hindbrain segments.

Answer 6

Hox

Question 7

Hox transcription factors encode early regional identity on the _______ axis.

Answer 7

antero-posterior (AP) axis

craniocaudal also an acceptable answer

Question 8

______ is linked to left-right asymmetry, and it is often associated with abnormalities in heart-looping and gut-looping.

Answer 8

Pitx2 (expressed on the left!)

Question 9

_____ promotes Tbx4 expression and is linked to early hindlimb development.

Answer 9

Pitx1

Question 10

In the distal limb, ______ expression plays a role in PD patterning and AP digit patterning.

Answer 10

Hox

Question 11

When _____ fails to regulate Hox in distal limb regions, various digit abnormalities such as syndactyly and polydactyly can result.

Answer 11

Shh