Zygotic gene activation III

Question 1

Where does the xenopus furrow initiate?

Answer 1

Animal pole

Question 2

Characteristics of the initial cleavage furrow?

Answer 2

20 µm wide contractile band

Question 3

Where are the cleavage furrow components assembled?

Answer 3

beneath surface

Question 4

Model of the cleavage furrow?

Answer 4

Purse string

Question 5

What does the initiation of the cleavage furrow define?

Answer 5

The division plane

Question 6

What does the surface next to the cleavage furrow do?

Answer 6

forms periodic stress folds

Question 7

How does division occur

Answer 7

filopodia interact with opposing cell surfaces across
cleavage furrow for daughter blastomere-blastomere adhesion

Question 8

How can the maternal factors be localised?

Answer 8

Prepatterened–> to animal or vegetal pole

Question 9

Animal pole maternal factors destination (germ layer)?

Answer 9

Ectoderm

Question 10

Vegetal pole maternal factors destination (germ layer)?

Answer 10

Endoderm + germ plasm

Question 11

Comparison of mouse and human preimplantation development?

Answer 11

Maiy similar, humans are slower

Question 12

ROle of Tet3?

Answer 12

oxidises 5mC to 5hmC/5fC/5caC to C

Question 13

What is 5caC?

Answer 13

5-carboxycytosine

Question 14

What DNA modification exits in bacteria but nor mammals?

Answer 14

methyladenosine

Question 15

Types of methyladenosine in bacteria?

Answer 15

6

Question 16

Type of methylcytosine in bacteria?

Answer 16

5-methylcytosine

Question 17

What happens to the paternal methylation after fertilisation but b4 the first cell division?

Answer 17

decreases sharply

Question 18

Which parental methylation is removed faster?

Answer 18

Paternal

Question 19

What happens to the maternally-inherited mRNA after fertilisation?

Answer 19

Gradually degraded, starting soon after fertilisation

Question 20

What is recruitment of maternally inherited mRNA?

Answer 20

polyadenylation and increased translation

Question 21

What type of polynucleotide is required for cleavage-stage development?

Answer 21

maternal RNA

Question 22

What is lineage specification?

Answer 22

the first embryonic cell differentiation

Question 23

How does pre-patterning occur in non-mammalian species?

Answer 23

maternally contributed specification factors (ie pre-determined in oocyte)

Question 24

How does pre-patterning/lineage specification occur in mammals?

Answer 24

first two lineages established in blastocyst due in part to chance

Question 25

What is lineage specification driven by?

Answer 25

Interplay between TFs

Question 26

What does the trophectoderm give rise to?

Answer 26

extra-embryonic tissue: placenta,chorion

Question 27

TFs involved in extra-embryonic tissue: placenta, chorion arising from the trophectoderm?

Answer 27

Tead4 (Hippo signalling pathway), Cdx2

Question 28

What does the inner cell mass give rise to?

Answer 28

EMbryonic tissue

Question 29

TFs involved in embryonic tissue arising from the ICM?

Answer 29

Nanog, Oct4, Esrrb, Sox2

Question 30

How is it decided if a cell becomes a morula or a trophectoderm?

Answer 30

Partly by chance

Question 31

First step of trophectoderm specification?

Answer 31

Cells on the outside have a YAP tf that isn’t phosphorylated

Question 32

What can unphosphorylated YAP do?

Answer 32

YAP can enter the nucleus of cells, and interact with Tead TF

Question 33

What do YAP and Tead TFs do?

Answer 33

Form a dimer

Question 34

Outcome of YAP and Tead dimer?

Answer 34

Together they activate genes responsible for specification of the trophectoderm Activate TFs like Cdx2

Question 35

What kind of signalling are the cells inside the blastocyst affected by?

Answer 35

Hippo

Question 36

First step of hippo pathway?

Answer 36

Kinases phosphorylated YAP

Question 37

Outcome of phosphorylation of YAP

Answer 37

PhosphoYAP remains cytoplasmic--> cant interact w/ Tead 4--> no upregulation of Cdx2

Question 38

Outcome of no upregulation of Cdx2?

Answer 38

No differentiation into trophectoderm, No repression of pluripotency programm

Question 39

Outcome of No repression of pluripotency programm?

Answer 39

Upregulation of many pluripotent related proteins