Amphibian gastrulation and primary embryonic induction- 17

Question 1

What is the combined study of evolution and development combined known as?

Answer 1

Evo-devo

Question 2

What are the ways Hox gene expression could be linked to different body plans?

Answer 2

A) change in Hox gene number
B) broad changes of Hox expression
C)subtle changes within Hox domains
D)changes in regulation or function of downstream genes

Question 3

What happens if UBX changes

Answer 3

If no ubx and Abd-A expression, anterior locomotor limb on thoracic segments is converted into a maxilliped.
In brine shrimp, if all thoracic segments express UBX and Abd-A there is no maxillipeds.
Lobster- lacks ubx and Abd-A expression in T1 and T2 maxillipeds are paired.

Question 4

What is the D11 gene critical for in Drosophilia?

Answer 4

for forming proximal-distal axis of appendeges

Question 5

Where is D11 expressed?

Answer 5

Expressed in head and thorax, inhibited by Abd-A and ubx in abdomen as linked to presence of appendages.

Question 6

Abd-A and ubx expression is later inhibited in patches of abdomen to allow what?

Answer 6

Expression of D11 and development of prolegs.

Question 7

Is there a difference in general pattern of Hox gene expression in flies and butterflies?

Answer 7

No.

Question 8

Many genes regulated by ubx in drosophilia are not regulated by ubx in butterflies

Answer 8

TRUE

Question 9

Future mesoderm and ectoderm lie where?

Answer 9

In the marginal zone immediately below the animal pole

Question 10

Gastrulation begins with what cells forming in the blastopore region?

Answer 10

Bottle cells

Followed by involution of mesoderm at dorsal lip and under ectoderm

Question 11

The marginal zone endoderm moves inwards under the mesoderm forming the roof of the

Answer 11

archenteron

Question 12

What is the name of the process in which the mesoderm move under ectoderm

Answer 12

Convergent extension

Question 13

The blastocoel reduces in size and….

Answer 13

blastopote sorrounds yolk plug.

Question 14

What is neurulation?

Answer 14

The inwardly migrating cells forming the roof of the archenteron. These cells will form the dorsal mesoderm

• In the middle notochord (spine)
• Dorso-lateral the somites (ribs)

Question 15

Neurectoderm cells that overlie the mesoderm cells are destined to form what?

Answer 15

The nervous tissue of brain and spinal cord.

• First form neural plate
• Then neural groove
• Finally neural tube

Question 16

Who coined the term primary embryonic induction?

Answer 16

Hanns Spemann

Question 17

What is primary embryonic induction?

Answer 17

The role of underlying mesoderm in specifying the fate of overlying ectoderm. Typically mesoderm will cause ectoderm to form neurectoderm.
Implanted mesoderm beneath presumptive ectoderm causes formation of neural structures.
INDUCTION OF WHOLE BODY AXIS

Question 18

Who discovered the importance of gray crescent for normal development?

Answer 18

Spemann

Question 19

What was the experimental procedure of Spemanns gray crescent study?

Answer 19

.Egg experimentally divided
.If gray crescent not present, no dorsal structures develop e.g. nervous
.Gray crescent region gives rise to cells that form the dorsal lip of blastopore

Question 20

Spemann 1918

Answer 20

Transplanted tissues between newt embryos of different species with different pigmentation. Results depended on age of embryo. Fate of transplanted tissue determined in later stages.

Question 21

Spemann and Manglod 1924

Answer 21

Fate of dorsal lip established early in development and is capable of inducing host embryo cells to change their fate.

Question 22

How does the spemann organiser form?

Answer 22

.B-catenin gradient
.Dishevelled protein in vegetal pole
-Dsh transported by microtubules
-GSK-3 normally degrades B-catening
-Is blocked by DSH in future dorsal region
SO FUTURE DORSAL NUCLEI RECEIVE B-CATENIN BUT FUTURE VENTRAL DOES NOT.

Question 23

What is the induction of the organiser signalled by?

Answer 23

Nieuwkoop centre

Question 24

Siamois gene normally repressed by

Answer 24

Tcf-3

Question 25

What does the siamois protein do?

Answer 25

Interacts with transforming growth factor-B proteins to control goosecoid transcription. Goosecoid protein activates genes in the organiser

Question 26

Examples of nuclear proteins:

Answer 26

Goosecoid
HNF3 B
Xnot

Question 27

Examples of secreted proteins:

Answer 27

Chordin
Dickkopf
Sonic hedgehog

Question 28

Bmp4 is what?

Answer 28

A bone morphogenetic protein that inhibits cells from forming neural tissues, expressed venterally during gastrulation.