Amphibian gastrulation and primary embryonic induction- 17 Flashcards
What is the combined study of evolution and development combined known as?
Evo-devo
What are the ways Hox gene expression could be linked to different body plans?
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
What happens if UBX changes
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.
What is the D11 gene critical for in Drosophilia?
for forming proximal-distal axis of appendeges
Where is D11 expressed?
Expressed in head and thorax, inhibited by Abd-A and ubx in abdomen as linked to presence of appendages.
Abd-A and ubx expression is later inhibited in patches of abdomen to allow what?
Expression of D11 and development of prolegs.
Is there a difference in general pattern of Hox gene expression in flies and butterflies?
No.
Many genes regulated by ubx in drosophilia are not regulated by ubx in butterflies
TRUE
Future mesoderm and ectoderm lie where?
In the marginal zone immediately below the animal pole
Gastrulation begins with what cells forming in the blastopore region?
Bottle cells
Followed by involution of mesoderm at dorsal lip and under ectoderm
The marginal zone endoderm moves inwards under the mesoderm forming the roof of the
archenteron
What is the name of the process in which the mesoderm move under ectoderm
Convergent extension
The blastocoel reduces in size and….
blastopote sorrounds yolk plug.
What is neurulation?
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)
Neurectoderm cells that overlie the mesoderm cells are destined to form what?
The nervous tissue of brain and spinal cord.
- First form neural plate
- Then neural groove
- Finally neural tube
Who coined the term primary embryonic induction?
Hanns Spemann
What is primary embryonic induction?
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
Who discovered the importance of gray crescent for normal development?
Spemann
What was the experimental procedure of Spemanns gray crescent study?
.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
Spemann 1918
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.
Spemann and Manglod 1924
Fate of dorsal lip established early in development and is capable of inducing host embryo cells to change their fate.
How does the spemann organiser form?
.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.
What is the induction of the organiser signalled by?
Nieuwkoop centre
Siamois gene normally repressed by
Tcf-3
What does the siamois protein do?
Interacts with transforming growth factor-B proteins to control goosecoid transcription. Goosecoid protein activates genes in the organiser
Examples of nuclear proteins:
Goosecoid
HNF3 B
Xnot
Examples of secreted proteins:
Chordin
Dickkopf
Sonic hedgehog
Bmp4 is what?
A bone morphogenetic protein that inhibits cells from forming neural tissues, expressed venterally during gastrulation.
