1. Is the fault in the components that perform any physical action?
Answer: Yes
2. Is the fault in components that move?
Answer: No
3. Is the fault in the mechanisms controls?
Answer: Yes
4. Is the fault in the components responsible for sending signals?
Answer: Yes
5. Is the fault only limited to non-sensory components?
Answer: Yes
6. Does the adaptation need to occur before deployment?
Answer: No
7. Can the replaced component be removed?
Answer: No
78) Zebrafish, Danio rerio
Zebrafish can be found in the tropical fresh waters of northern India, northern Pakistan, Nepal, and South Asia. They can grow up to 4-5 centimeters in length and get their name from stripes on their body (Hamel & Mercier). Zebrafish can regenerate their spinal cord.
After the spinal cord is damaged multiple signals, such as Wnt, BMP/TGF beta, and JAK-STAT, are relayed to start the regeneration process (Hui et al.). One of those signals is the inflammatory response which allows macrophages to migrate to the wound and clear the debris. Microglial cells that are found to be stem cell-like migrate to the wound as well and start proliferating (Hui et al.). The cells will form a bridge connecting the two stumps together and differentiate into the spinal cord. Some of the cells will also differentiate into NeuroD positive cells and become neuron cells (Hui et al.). These cells will join together and form a neuroepithelium which will allow for nerve signals to be passed along (Hui et al.). The microglial cells also differentiate into various tissues that make up and surround the cord. Once the spinal cord and neurons have been regenerated the signals for regeneration will stop being produced and migrate away from the previous wound site.
Hamel, J.-F. & Mercier, A. 2013. Apostichopus japonicus. The IUCN Red List of Threatened Species. Version 2014.3. Web. 14 Dec. 2014.
http://www.iucnredlist.org/details/180424/0
Hui, Subhra Prakash, Dhriti Sengupta, Serene Gek Ping Lee, Triparna Sen, Sudip Kundu, Sinnakaruppan Mathavan, and Sukla Ghosh. “Genome Wide Expression Profiling during Spinal Cord Regeneration Identifies Comprehensive Cellular Responses in Zebrafish.” PLoSONE (2014): n. pag. PLoSONE. Web. 15 Dec. 2014.
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0084212#s3
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