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: No
5. Does the faulty component control any other functions in the mechanism?
Answer: Yes
48) 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 retinal neurons if damaged so they can convey the information they perceive through their eyes to the brain.
After the retina has been damaged Muller glia cells dedifferentiate and proliferate. These cells produce neuronal progenitor cells that proliferate and migrate to the damaged portion of the retina (Gorsuch & Hyde). Once there the progenitor cells differentiate into the various neuronal cells to fill in the damaged portion of the retina. The corepressors Tgif1 and Six3b regulate TGFbeta signaling and the signals are critical to help induce proliferation of photoreceptors (Lenowski et al.). Once the retina has been regenerated the Muller glia cells will stop dedifferentiating and go back into the quiescent stage of mitosis until needed later.
Hamel, J.-F. & Mercier, A. 2013. Apostichopus japonicus. The IUCN Red List of Threatened Species. Version 2014.3. Web. 7 Dec. 2014.
http://www.iucnredlist.org/details/180424/0
Gorsuch, R. A., and D. R. Hyde. “Regulation of Mller Glial Dependent Neuronal Regeneration in the Damaged Adult Zebrafish Retina.” Experimental Eye Research 123 (2014): 131-40. NCBI. Web. 7 Dec. 2014.
http://www.ncbi.nlm.nih.gov/pubmed/23880528
Lenkowski, J. R., Z. Qin, C. J. Sifuentes, R. Thummel, C. M. Soto, C. B. Moens, and P. A. Raymond. “Retinal Regeneration in Adult Zebrafish Requires Regulation of TGF_ Signaling.” Glia. 61.10 (2013): 1687-697. NCBI. Web. 7 Dec. 2014.
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