Tuesday, November 27, 2012

Zebrafish make it to Hollywood!


The zebrafish is not just your average minnow, it is a model organism commonly studied because of its rapid development, see through embryo and easily maniputable genome.  Dr. Schroeder’s lab at Loyola University Chicago, is researching the development of this organism.  Specifically, Dr. Schroeder is studying the development of neurons, mostly retinal cells, which include the bipolar cells and ganglion cells. These cells are neurons responsible for vision in the fish (similarly in humans).  Dr. Schroeder uses gateway cloning in order to extract, clone and tag a specific gene in the zebrafish. Then, using a fluorescent protein, the development of the zebrafish can be studied. But why would one study the development of the zebrafish? I mean, come on, even if it is a model organism, how cool can this fish really be?
                                          Zebrafish transparent embryo in laval development

Well, like I said before, zebrafish are not your average minnow, because of their unique developmental and genomic characteristics, the zebrafish has been studied in various areas in biology. Which is why zebrafish have made it to Hollywood, or at least have been a forerunner in modern biomedical research. For example there are genetically modified zebrafish able to detect oestrogen, a pollutant in lakes and rivers.  Zebrafish have also been used to study cancer, drug treatments, and regeneration. Yes, you read that correctly, zebrafish have regenerative capabilities of various parts of the body such as limbs, cardiac muscle, and neural cells.  Cut the zebrafish’s heart, injure its retina or spine… and it will heal itself- it will regenerate. Stem cells can be generated from zebrafish to help heal with diseases and trauma in humans.
                                          Fibroblast growth factor expressed in Zebrafish

Humans most likely do not regenerate due to an evolutionary trade off (suppressing cell growth in order to reduce cancer). After a spinal or retinal injury, the glial cells scar to prevent bleeding and further injury. This also prevents axons from getting access to the injured area, and does not allow regeneration. In zebrafish, the glial cells form a bridge that spans across the injured site. However, the glial cells allow for axon access. The injured site can, therefore, be regenerated.  Scientists at Monash University discovered a protein called the fibroblast growth factor, which accounts for the shape of glial cells and how they react to injury. This accounted for the differences between humans and zebrafish. This discovery can eventually lead to human neural repair. Other genes can lead to cardiac and limb repair. So if you thought nothing of zebrafish in the past, think again- this little organism could be the regenerative hero for humans in the near future.



Sources
http://www.futurity.org/health-medicine/zebrafish-protein-bridges-spinal-cord-injury/
http://www.sciencedaily.com/releases/2012/07/120706184353.htm
Schroeder, Eric et. al.,  In Vivo Development of retinal ON-bipolar cell axonal terminals visualized in transgenic zebrafish. Feb 2006.

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