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UVic BIOL 309 - Spring 2019 > Neural Development > Flashcards

Neural Development Flashcards

1
Q

What 4 steps outline vertebrate neural tube formation?

A
  1. Shaping and initial folding
  2. Elevation (of sides)
  3. Convergence (of sides)
  4. Closure and separation of neural tube from epidermis
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2
Q

How do the cells of the neural plate change during folding?

A

The mediolateral edge shrinks, turning the cells wedge-shaped.

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3
Q

What pathway mediates the folding of the neural plate and the change in shape of the neural plate cells?

A

The Planar Cell Polarity (PCP) signalling pathway.

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4
Q

What 2 functions does the Planar Cell Polarity signalling pathway drive?

A
  1. Convergent extension

2. Apical constriction

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5
Q

How is the Planar Cell Polarity signalling pathway activated?

A

By non-canonical Wnt signalling.

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6
Q

In the Planar Cell Polarity signalling pathway, how are cadherins interactions at adherens junctions maintained?

A

By the action of Celsr1 at the apical membrane.

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7
Q

In the Planar Cell Polarity signalling pathway, how is actino-myosin contraction mediated?

A

By the action of PDZ-RhoGEF (downstream of Wnt).

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8
Q

What do we call the cells that are left over between the neural tube and the epidermis immediately after neural tube formation?

A

Neural crest cells.

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9
Q

What is spina bifida?

A

A human defect arising from the failure of neural tube closure.

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10
Q

What genes are involved in spina bifida? How can the expression of this gene be altered?

A

Alx1, Pax3, Alx3. Needs folic acid for expression. If mother doesn’t get enough folic acid during pregnancy then spina bifida can occur.

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11
Q

Why does lack of folic acid during pregnancy put a child at risk of spina bifida?

A

Folic acid activates lipoprotein receptor SR-BI which activates Alx1, Pax3, Alx3.

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12
Q

What do vertebrates have during development that other chordates don’t have?

A

The neural crest!

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13
Q

What gene has been shown to be critical for neural crest differentiation?

A

FoxD3.

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14
Q

What is sometimes referred to as “the 4th germ layer”?

A

The neural crest!

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15
Q

What tissues do neural crest cells give rise to?

A

PNS, endocrine structures, pigment cells, facial cartilage/bone, connective tissue.

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16
Q

Are neural crest cells multipotent? How was this determined?

A

Yes, through fate-mapping experiments.

17
Q

What mechanism specifies the fate of neural crest cells in different areas of the body?

A

Local paracrine signalling cues and regulatory transcription factors.

18
Q

In addition to mesoderm, neural crest cells can also give rise to ____. What kinds of cells are these?

A

Bone. As osteoblasts and eventually osteocytes.

19
Q

What can result from neural crest defects?

A

Truncated or totally absent structural tissues (ex: missing clavicles, etc.)

20
Q

What did Julia Platt show regarding neural crest cells?

A

That they can also produce bone (at the time, dogma was that only mesoderm became bone).

21
Q

What is DiGeorge syndrome?

A

A disease resulting in a connection between the aorta and pulmonary artery (aortopulmonary window).

22
Q

What causes DiGeorge syndrome? What TF is missing?

A

The neural crest cells that are supposed to differentiate into cardiac tissue fail to migrate to the heart and form a septa. Lacking Tbx1.

23
Q

Cells in Ciona intestinalis have similarities to neural crest cells. What are they missing?

A

Transcription factor “twist”, which can cause them to exhibit the same migration as neural crest cells.

24
Q

What patterns the AP axis (with neural ectoderm) in Xenopus?

A

A Wnt morphogen gradient. + Hox genes

25
Q

How is DV polarity established in the neural tube?

A

Sonic hedgehog (Shh) secretions from the notochord (ventral) and BMP4/Wnt secretion from the ectoderm (dorsal).

26
Q

What are the 5 TF subsections established by the Shh morphogen gradient in the neural tube? (dorsal to ventral)

A
  1. Pax7
  2. Pax7+Pax6
  3. Pax6
  4. Pax6+Nkx6.1
  5. Nkx6.1
27
Q

What are the 3 components of Axon Guidance?

A
  1. Pathway selection
  2. Target selection
  3. Address selection
28
Q

Describe the “pathway selection” component of Axon Guidance.

A

Developing neuron (axon) must find a way to get to the target cell.

29
Q

Describe the “target selection” component of Axon Guidance.

A

Developing neuron (axon) must form synapses with the appropriate target cell.

30
Q

Describe the “address selection” component of Axon Guidance.

A

Developing neuron (axon) must prune synapses to remove sub-optimal connections.

31
Q

How is growth of the growth cone at the end of the growing axon regulated?

A

Extracellular matrix glycoproteins signal Rho GTPases to make adjustments to the actin/microtubule cytoskeleton.

32
Q

According to Rita Levi-Montalcini’s experiments, what happens to the growing peripheral neurons when you cut off the limb bud they’re trying to grow into?

A

The developing peripheral neurons die.

33
Q

What is the function of nerve growth factor (NGF)(neutrophins)?

A

Promote axon outgrowth, survival, and differentiation.

34
Q

What 4 molecules are responsible for guiding the growing axon?

A
  1. Ephrins
  2. Netrins
  3. Slit
  4. Semaphorins
35
Q

What general mechanism can describe the action of axonal guidance molecules?

A

Some give off repulsive signals on one side of the axon while others on the opposite side give off attractive signals, turning the axon.

36
Q

What is present in the spinal cord that prevents mechano and pain/temp neurons from projecting ventrally?

A

Semaphorin 3 is present in the ventral region of the spinal cord.

37
Q

How did researchers originally figure out the somatosensory cortical map?

A

By shocking specific parts of a conscious patients brain and noting where they felt it.

38
Q

How are sensory maps generated in the retina?

A

Ganglion cells are guided by an ephrin gradient in both axes coupled with Eph-EphR repulsion (low nasal EphR, high lateral EphR).

UVic BIOL 309 - Spring 2019 (9 decks)

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