Zebrafish in regeneration

Question 1

why are zebrafish interesting?

Answer 1

they are vertebrates

Question 2

what is epimorpic regen?

Answer 2

• occurs in the newt limb being cut off and then the limb can regenerate: completely patterned limb
• blastema forms which contains intrinsic information required to re pattern the regenerating structure. The regeneration is dedifferentiation of cells or stem cell based.

Question 3

what happens in the blastema during regen?

Answer 3

the epithelial cells of the blastema signals to the cells to dedifferentiate back to a primitive mesenchymal like cell and these proliferate- then they redifferentiate

Question 4

what is compensatory growth?

Answer 4

• organs are able to compensate for damage
• instead of dediff and repatterining, the components are replaced but the liver isn’t repatterned - cells will grow and replace some of tissue

Question 5

what is tissue regeneration as a regen method?

Answer 5

• local tissue regeneration and repair
• repair of one cell type
• good example is human skeletal muscle where the sat cells are stimulated and will proliferate and regen

Question 6

what makes a good animal model for regeneration?

Answer 6

Easy to breed
• Easy to maintain in the lab
• Genetically tractable
• Bear some relationship to man
• Good natural regeneration capacity

Question 7

why are mammals rubbish at regen?

Answer 7

• the only thing that a mammal can regenerate is the deer antler via an epitmorphic process
• the others are very poor

Question 8

what can zebrafish regenerate?

Answer 8

• heart, liver, fins, spina cord and kidney, brain and eye

Question 9

why is bad transparency bad for a model?

Answer 9

can’t do lineage tracing of cells during regen

Question 10

why is it hard to use invertebrates in invertebrate models?

Answer 10

they dont always have analogous tissues

Question 11

are vertebrate lineages quite autologous?

Answer 11

yes

Question 12

why are deer bad in terms of breeding?

Answer 12

they breed seasonally

Question 13

what little thing is good for regen?

Answer 13

the planaria

Question 14

what is bad and good about the plenaria?

Answer 14

they are not very similar to humans

Question 15

what is hard about using a newt?

Answer 15

hard to make KO- not very genetically tractable

Question 16

how long can a tail fin take to regen generally?

Answer 16

around 7 days

Question 17

what type of regen occurs int he tail fin?

Answer 17

epimorphic regeneration- de diff and re diff of tissues = from the cut ray- the osteoblasts

Question 18

how did they find out which genes were involved in fin regeneration?

Answer 18

they carried out a screen

Question 19

what factors are involved in fin regen? what does this resemble?

Answer 19

Fgf, WNT in the blastema
fgf shh and cell cycle regulator in outgrowth
BMP and runx2 in rediffereniation
- the development

Question 20

how can you label a heart in the ZF?

Answer 20

use promoter to drive the heart

Question 21

what are the 3 ways to injure the heart?

Answer 21

• ventricular resection
• cryoinjury - cold probe
• genetic cardiomyocyte ablation

Question 22

what is the process of repair in the ZF heart?

Answer 22

• amputate, activation of blood clot which activates the endocardium lining and GF production, then fibrin clot forms which activates the pericardium which activate GFR and pathways to stimulate proliferation
• wihtin 7 days get activation of cardiomyocytes and start proliferating and new blood vessel formation
• within 30 days there is a repaired heart

Question 23

hat factors that works in ZF heart regen doesn’t work in mammalian heart

Answer 23

BMP signalling driving proliferation

Question 24

what is the role of the endocardium

Answer 24

first tissue responding, produces RA which also promotes regen

Question 25

what is the role of the epicardium

Answer 25

Epicardium activation promotes angiogenesis through
production of growth factorsMammalian cardiomyocytes do not proliferate well but epicardium does secrete some growth factors

Question 26

ow are ZF hearts different to mammals? why is this interesting

Answer 26

they are mononucleate
Mammalian embryonic/early postnatal hearts are mononucleate too.
• Mouse hearts will regenerate up to P7
• There are small pools of mononucleate cells in
mammalian adult hearts

Question 27

how were mammal hearts made to rpoliferare

Answer 27

in the ZF injured heart miR26i are downrgelated but not in mammalian injured heart- theses were inhibited in mammal heart and started to proliferate

Question 28

what do mammal muller cells do when they divide?

Answer 28

divide symmetrically and form a scar