VL14 - Model organism to study regeneration

Question 1

Definition on Regeneration

Answer 1

Regeneration = replacement of a lost or damaged tissue, which includes the structural and functiinal restoration of the organ

e.g: in Hydra

Question 2

Hydra - freshwater polyp

Answer 2

• Phylum Cnidarians , Class Hydrozoa
• kept as mass cultures at 18°C, fed with brine shrimps
• Hydra vulgaris –> most comonly used
• Genome was sequenced in 2010 by Chapman et. al.

Whole body generation:
* Regenrate whole body parts
* Three diffrent stem cell pools are involved in regeneration
- Ectodermal epthelial cells (unipotent)
- Endodermal (gastrodermal) epithelial clls (unipotent)
- Interstitial stem cells (multipotent) –> migrate to the wound

• Establishment of an organizer (Head and foot)
• Wnt signalling is required for head organization.
• Apoptosis inhibition at foot tip prevents head regeneration
  –> Apoptotic cells provide an unexpected source of Wnt3 Signaling to drive hydra head regeneartion.
• crosstalk between cell layers and cell types

https://www.youtube.com/watch?v=ITVfXHrfudw

Question 3

Why is Hydra useful?

Answer 3

• Wound healing
• Developmental processes
• whole body regeneration
• Regeneration from dissociated tissue “natural organoids”

Question 4

Planaria

Answer 4

• cheap an easy maintanence
• only some are regenerative
• Genome assambly available for S. Mediterranea and D.Japonica
• Stem cell ablation via irradiation
• Transplantation of single-cells and tissue
• Whole body regeneration occurs through neoblasts

Whole body generation:
* Neoblast dpread over whole body
* regerate all organs
* Express piwi1, smedwi-1
* capable of deviding
* can be devided in subclasses

Question 5

Regenerative capacities in different species

Answer 5

Question 6

Salamander