Medical research have seen that Zebrafish have been used to make several transgenic models of cancer, including melanoma, leukemia, pancreatic cancer and hepatocellular carcinoma. Even in cardiovascular research, the zebrafish has been used to model blood clotting, blood vessel development, heart failure, and congenital heart and kidney disease. In fact, in programmes of research into acute inflammation, a major underpinning process in many diseases, researchers have established a zebrafish model of inflammation, and its resolution. This approach allows detailed study of the genetic controls of inflammation and the possibility of identifying potential new drugs.
Another notable characteristic of the zebrafish is that it possesses four types of cone cell, with ultraviolet supplementing the red, green and blue cone cell subtypes found in humans. Zebra fish can thus observe a vast spectrum of colours. The species is also studied to better understand the development of the retina; in particular, how the cone cells of the retina become arranged into the so-called 'cone mosaic'. Zebrafish, in addition to certain other teleost fish, are particularly noted for having extreme precision of cone cell arrangement and that Stem cells from zebrafish, the staple of genetic research, could regenerate damaged cones in retinas and restore eyesight to people. Rods and cones in the eyes are the most important photoreceptors. In humans, rods provide night vision, while cones offer a full-colour look at the world during the day.
To say more, this study of the zebrafish's retinal characteristics has also extrapolated into medical enquiry. In 2007, researchers at University College London grew a type of zebrafish adult stem cell found in the eyes of fish and mammals that develops into neurons in the retina. These s could be injected into the eye to treat diseases that damage retinal neurons—nearly every disease of the eye, including muscular degeneration, glaucoma, and diabetes-related blindness. The researchers studied Muller glial cells in the eyes of humans aged from 18 months to 91 years, and were able to develop them into all types of retinal neurons. They were also able to grow them easily in the lab. The stem cells successfully migrated into diseased rats' retinas, and took on the characteristics of the surrounding neurons.
Moreover, University of Alberta researcher Ted Allison says that it was not known that whether stem cells could be instructed to only replace the cones in its retina. This could have been important implications for human eyesight, the journal Public Library of Science ONE reports.
It seems, almost all success in regenerating photoreceptor cells to date had been limited to rods, not cones. Most previous experiments were conducted on nocturnal rodents, animals that require good night vision and have far more rods than cones, according to Alberta's statement.
Researchers say this shows some hope for stem cell therapy that could regenerate damaged cones in people, especially in the cone-rich regions of the retina that provide daytime/colour vision.
Allison says that his team would be looking for the next step that is to identify the particular gene in zebrafish that activates repair of damaged cones.
A WONDER FISH!
(AW:Samrat Biswas)
