BGM1004/L22 Vertebrate Development

Question 1

When does patterning occur?

Answer 1

Initiated on day 12

Question 2

What is morphogenesis?

Answer 2

Process by which an organism or structure begins to develop 3-dimensional form

Question 3

Give the 3 fundamental processes of developmental biology.

Answer 3

Morphogenesis
Cell differentiation
Growth

Question 4

Define axis formation.

Answer 4

Establishment of body plan

Question 5

What is body plan?

Answer 5

Map of an organism developed by three axis

Question 6

Give and define the 3 axis.

Answer 6

Antero-posterior axis - head to tail
Dorso-ventral axis - back to belly
Left-right axis - as stated

Question 7

Give another name for the anterior end of the embryo.

Answer 7

Rostral
Cranial

Question 8

Give another name for the posterior end of the embryo.

Answer 8

Caudal

Question 9

What is body axis formation dependent on?

Answer 9

Different parts of the embryo becoming distinct

Question 10

Name the 4 components to cell signalling.

Answer 10

Release and transmission of signal by source cell
Reception by target cell
Transduction
Cellular response

Question 11

Give 2 example of cellular responses to cell signalling.

Answer 11

Differentiation
Proliferation
Cell shape change
Migration
Death

Question 12

What signalling molecules pattern the embryo?

Answer 12

Growth factors/ morphogens

Question 13

How do morphogens control positioning of specialised cell types?

Answer 13

Form gradients which activate/repress different genes at different concentrations

Question 14

What is the role of the protein bicoid in flies?

Answer 14

First step in establishing A-P polarity

Question 15

Give 2 ways that morphogens achieve long range signalling in cellularised tissues.

Answer 15

Diffusion over long distances
Relay from cell to cell
Cellular extensions

Question 16

Describe the role of the Sonic Hedgehog (Shh) protein.

Answer 16

Crucial vertebrate morphogen

Question 17

Name the 2 main signalling centres in early mammalian embryos.

Answer 17

Anterior visceral endoderm (AVE)
Node (organiser)

Question 18

What gene is crucial for the formation of the anterior visceral endoderm?

Answer 18

Lim-1

Question 19

Name 3 genes that severely affect body plan when knocked out.

Answer 19

Lim-1
Chordin
Noggin
Shh

Question 20

Where does breaking of left-right symmetry first occur?

Answer 20

At the node

Question 21

Name 2 morphogens involved in left-right axis formation.

Answer 21

Shh
RA
FGF

Question 22

Describe how morphogens create left-right axis in vertebrates.

Answer 22

Activates specific signalling pathway only in left side

Question 23

Describe the L-R signalling pathway (4)

Answer 23

Initiated at node
Release of morphogens
Nodel signalling activated on L side
Nodal activates Pitx2
Downstream gene expression activated

Question 24

Which side of the body is default?

Answer 24

Right side - left actively specified

Question 25

What is the role of Homeobox gene Pitx2? (2)

Answer 25

Regulates downstream gene expression Governs asymmetric organ development

Question 26

What tools are used to determine L-R patterning? (2)

Answer 26

Physical inversion and transplantation of node Genetic knockout of Lefty-1 or Shh gene

Question 27

What occurs when Lefty-1 or Shh are knocked out?

Answer 27

Both sides present as 'left'

Question 28

What occurs when the nodal is on the right side of the body?

Answer 28

Situs inversus totalis Total inversion of organs No effects

Question 29

What occurs when the nodal is on both sides/ neither side?

Answer 29

Left isomerism Right isomerism Poor prognosis

Question 30

What occurs in situs inversus thoracalis?

Answer 30

Thoracic organs are inverted Poor prognosis

Question 31

What occurs in situs inversus abdominalis?

Answer 31

Abdominal organs are inverted Poor prognosis

Question 32

What is the role of Wnt in AP axis formation?

Answer 32

Specifies early anterior region

Question 33

What is the role of RA in AP axis formation?

Answer 33

Patterns midbrain, hindbrain and trunk

Question 34

What is the role of FGF in AP axis formation?

Answer 34

Patterns the caudal region

Question 35

Which genes code for vertebrae with/without ribs?

Answer 35

Hox6 Hox10 respectively

Question 36

Which 2 morphogens determine neuronal sub-types? By which mechanism?

Answer 36

Shh and BMP Opposing gradients

Question 37

Describe the patterning of the neural tube.

Answer 37

BMP and Wnt determine from dorsal region Shh determines from vental region

Question 38

Where are the signals required for limb outgrowth?

Answer 38

Apical ectodermal ridge (AER)

Question 39

What morphogen principally determines limb outgrowth?

Answer 39

FGF8

Question 40

How does thalidomide disrupt limb patterning? (3)

Answer 40

Stops production of blood vessels Blocks proliferation Alters expression of Shh, FGF and Hox genes

Question 41

SALL4 mutations have been shown to cause what syndrome?

Answer 41

Duane Radial Ray Syndrome

Question 42

How do teratogens act?

Answer 42

Disrupt patterning signals and genes