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Developmental and stem cell biology > establishment of the body plan > Flashcards

establishment of the body plan Flashcards

1
Q

how is the A/P and D/V axis set up in Drosophila?

A

‘maternal’ genes

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2
Q

what do the cystoblasts do in drosophila oogenesis

A

Divide 4 x to produce 16 cells

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3
Q

how the oocyte and nursel cells are different from one another (3)

A
  • oocyte is larger in size
  • oocyte is located at anterior end
  • oocyte recieves nutrients from other cells
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4
Q

how is the proten machinary to activate the spatzle ligand established in the drosophila egg? (2)

A
  • egg polarity
  • drosophila embryos exibit unique egg polarity that is established in the mother’s ovaries
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5
Q

what are the mammalian orthologues of Dorsal and Cactus?

A
  • NfkB
  • IkB
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6
Q

what does the development of the A/P and D/V axis in drosophila up to the end point of oogenesis describe the importance of? (2)

A
  • the localisation of maternal factors
  • crucial for development of the A/P and D/V axis
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7
Q

what are the 2 key featuresof the egg that occur when it is laid

A
  • Bicoid RNA is localised at the anterior
  • the machinery to produce processed Spatzle is localised ventrally
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8
Q

what is a syncytium in terms of cells?

A
  • a cell tht has lots of nuclei in a common cytoplasm
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9
Q

what is the Kruppel gene? (2)

A
  • a key member of the gap gene class in drosophila
  • involved in establishing the segmentation pattern along the A/P axis of the developing embryo
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10
Q

what is a sequential pathway? (3)

A
  • a series of ordered and interconnected cellular events that occur after one another
  • achieves a particular biological function/ response
  • play essential roles in various biological processes
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11
Q

the 2 main steps in segmentation of the embryo:

A
  1. “gap” genes regulate ‘pair-rule’ genes to define 14 parasegments
  2. segment polarity genes stabilize boundaries between para-segments
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12
Q

how are the stripes of expression of the pair all genes defined?

A
  • local concentrations of the TFs that are produced by the gap genes
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13
Q

what are the 2 functions of the segmentation genes?

A
  1. stablise parasegment boundaires
  2. establish cell fate within each parasegment
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14
Q

when are the segmentation genes expressed?

A
  • in response to pair-rule genes (even skipped)
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15
Q

what are the two gradients involved in the D/V axis of drosophila?

A
  • Dorsal
  • Dpp
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16
Q

how are the bands made different from one another?

A
  • Hox genes
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17
Q

where is vertebrate A/P patterning seen the best?

A
  • in differences in vertebrae
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18
Q

what are somites? (5)

A
  • segmental blocks of tissue
  • form during embryonic development
  • form in pairs on either sie of neural tube
  • crucial in segmentation of developing vertebrate embryo
  • development and differentation are regulated by expression of Hox genes
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19
Q

3 examples of deletion/ectopic expression of hox genes that changes axial patterning?

A
  • knock out of hox c8
  • knockout of all hox 10 paralogues (similar with all Hox 11)
  • ectopic expression of Hoxa7
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20
Q

what are paralogues?

A
  • is an umbrella term for all the similar versions of Hox genes in mammals
21
Q

how to determine where a hox gene functions along A/P axis:

A
  • hox genes that are expressed first and most proximally affect proximal structures
22
Q

why do Xenopus embryos have a different animal -vegetal axis? (3)

A

to protect from predators in the pond:
* dark side faces up

its not corelated to any furutre embryonic axis

23
Q

put simply, what is the point gastrulation

A

invagination, in order for the cell layers to move around

24
Q

what is the main difference between gastrulation in zebrafish and Xenopus?

A
  • in zebrafish, the cells have to move on top of a big yolk sac
25
Q

what is the yolk cell function in zebrafish (2)

A
  • nutrient storage
  • support for organogenesis
26
Q

what does teleost mean?

A

bony

27
Q

what is the phylotypic stage of development (4)

A

refers to the stage in which the main properties of the phylum are apparent:
* notochord
* tubular dorsal CNS
* somites

28
Q

what is cortical rotation?

A

the movement of the superficial layer of the cytoplasm (the cortex), relative to the denser cytoplasm core

29
Q

what are Dorsal determinants? (3)

A
  • components of the Wnt pathway
  • translocation results in local activation of the Wnt pathway
  • are prerequisites for the establishment of the dorsal side
30
Q

what happens if activation of thhe Wnt pathway is everywhere in the early cleaving embryo?

A

No tail and trunk structures,

31
Q

what is the difference between amniotes and anamniotes?

A

amniotes = vertebrates that produce an amniotic egg during embryonic development
anamniotes = vertebrates that do not produce an amnitoic egg during embryonic development

32
Q

are mammals amniots or anamniotes?

A

amniotes

33
Q

what does it mean if a cell is ‘regulative?

A
  • refers to the ability of the cells in the embryo to compensate for changes or disturbances int their environment during early stages of development
34
Q

at what stage is the dorso-ventral axis specified in Xenopus?

A

4 cell stage

35
Q

when is the dorso-ventral axis specified in the mouse?

A

16-32 cell stage

36
Q

what is the Nieuwkoop centre?

A
  • a specific region in the embryo that plays a crucial role in establishing the DV axis (back and belly)
37
Q

what is the Nieuwkoop known as later in development

A

the early organiser

38
Q

what is the organiser? (3)

A
  • a later stage of the Nieuwkoop centre
  • patterns the entire body axis
  • also known as the amphibiean “dorsal liip”
39
Q

the mechanism through which the Beta-catenin pathway is acting: (2)

A
  • operates by interacting with VegT - a maternal TF
  • induces expression of Nodal genes
40
Q

what does early Wnt signalling do in relation to the development of the orgnaiser in Xenopus? (2)

A
  • activates target gene ‘Siamois’
  • siamois encodes a TF that regulates genes expressed in the organiser
41
Q

is Wnt involved in the organiser in all 4 vertebrate models?

A

yes - but details differ

42
Q

what are the ‘Organisers’ called in Xenopus, Zebrafish, Chick and Mouse

A

Xenopus - organiser
Zebrafish - Shield
Chick - Hensen’s node
Mouse - Node

43
Q

by what transcription factors is Nodal expressed?

A
  • VegT
  • Wnt signalling
44
Q

what is VegT? (2)

A
  • A maternal mRNA expressed in the Vegetal hemisphere of the Xenopus embryo
  • involved in establishment or dorsoventral (DV) axis and endoderm formation
45
Q

what is a specification assay?

A
  • an experiment involving removing parts of an embryo and growing them seperately to see what each part will become
46
Q
A
47
Q

by what cells in the embryo is the mesoderm induced? (2)

A
  • animal cap cells
  • by signals from the Vegetal pole
48
Q

what is the main inducer of the mesoderm discovered initial experiments?

A
  • Nodal
49
Q

the development of the Dorso-anterior structures requires what signals? (3)

A
  • low BMP
  • Low Wnt
  • Low Nodal

Developmental and stem cell biology (3 decks)

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