Regeneration Flashcards
What is regeneration?
The possibility of the fully developed organism to replace organs by growth or by re-patterning of existing tissues
What is morphallaxis? What organism demonstrates morphallaxis?
Regeneration by the transformation of existing tissues.
Hydra- cells are constantly changing their position
What 2 gradients are involved in hydra regeneration?
- Positional value gradient- determines the head inducing ability
- Head inhibitor gradient- produced in the head itself
What is expressed in the hydra head and regenerating tip?
Wnt
What is epimorphic regeneration?
Growth of new tissue
What happens after amputation in urodeles?
Epithelial cells migrate over the wound surface, epithelial cells below dedifferentiate- form the cells needed
What is required for muscle dedifferentiation?
- Expression of msx (homeobox t factor)
- Inactivation of rb gene
- Presence of thrombin
What are the rules of regeneration?
- Limb regeneration is always distal to the wound- occurs according to the positional value at the site of the cut
- Normal limb innervation
What can reset a positional value to be more proximal?
Retanoic acid
What happens in cockroach regeneration?
Missing positional values are filled in, irrespective of the overall structure
What is involved in ventricular regeneration in zebra fish?
The epicardium and endocardium
How does regeneration in the zebrafish heart occur?
- Heart bleeds
- Blood clot forms
- Endocardium is activated and starts to express specific genes
- Epicardium expands and covers the wound
- Epicardial cells will respond to FGF signalling via newly formed muscle and invade the regenerating tissue- form new blood vessels
What do neonatal mice lose soon after birth?
The ability to regenerate their heart
What do zebrafish mps1 mutants show?
Scarring instead of regeneration
What is expressed in the nerve sheath and allows regeneration?
nAG (newt anterior gradient)- can rescue a denervated limb
binds to prod1
