3. Nervous system regeneration Flashcards
Can vertebrates regenerate CNS?
Yes, some can - zebrafish, salamanders - but not common
The simpler the system, the more capacity to regenerate
Why are zebrafish good for studying regeneration?
Zebrafish - good model because:
- vertebrates - closer to humans - well conserved mechanisms with mammals
- reproduce / develop quickly
- external fertilization
- see through embryos - easy to mark and track target cells
Explain how zebrafish can regenerate their CNS
Zebrafish can fully restore spinal lesions within 6 weeks - functionality restored - although a scar can be seen where regenerated
What could be the reasons why mammals have lost so much capacity for brsain regeneration?
Mammals have lost a lot of capacity for brain regeneration because:
- are too complex to rebuild, go through all the complex developmental mechanisms, hard to integrate half-functional cells into a highly complex network
- mammals too large to regenerate - would take a long time - mammal life is not compatible with resting and waiting for regeneration for ex. 6 months
- cancer risk when introducing stem cells into differentiated tissues
Why is successful spinal cord regeneration difficult?
A lot of complex mechanisms involved
In mammals axons don’t grow into the lesion area - cannot re-establish neuron networks
What are the molecular pathways drive neurogenesis?
Neurogenesis is driven by the same molecular pathways as development - reused gene networks
Why do zebrafish regenerate spinal lesions but mammals don’t?
The axons of zebrafish cross into the lesion site whereas in mammals don’t
Even when zebrafish regenerate spinal lesions - tissue not perfectly restored - morphologically can be differentiated where the lesion was made - but function restored
What is a recent biology advancement allowing better study of molecular basis for regeneration?
CRISPR-Cas9 gene targeting technology allows precise investigtaion of molecular basis
Which gene has been found to be important for regeneration?
tg1ba - loss of tg1ba leads to neutrophils staying at the injury site longer - impairs regeneration
Discussion points to consider
?? idk read
Explain what is myelin
Myelin - fatty, insulating substance that surrounds the axons of nerve cells - insulates axon - speed up the transmission of electrical signals throughout the body
Myelin - white matter of the brain
How is myelin deposited on nerve cells
Myelin in CNS is deposited by oligodendrocytes
What are the beneifts of myelin
- rapid impulse propagation
- support
- NS health and function
Is myelination an ongoing process throughout life?
No, peaks ~30 years then declines - age loss of myelin -> mutliple sclerosis
Hope to regenerate myelin???
Is mylein regeneration possible?
Myelin can be regenerated - 5% of CNS cells are oligodendrocyte progenitors (OPCs) - they can generate myelin throughout life following loss of myelin in disease/injury - neuroprotection
What happens if nerves lack myelin over long term?
Nerves without myelin degenerate
How are zebrafish observed under the microscope?
Grown in 96 well plates - in tubing taken to microscope
Overview - using zebrafish as nervous system regenerative model
