With its characteristic striped skin, the zebrafish ( Danio rerio ) is in itself striking, a common inhabitant of both aquariums and biologists’ laboratories, where transgenic specimens of garish fluorescent colors had already been bred. It has also been achieved with other animals. Now, an article published in Development cell magazine has just revealed a new feat of genetic manipulation on this freshwater species: a specimen that emits thousands of colors, putting on a mind-blowing spectacle.
The experiment has been carried out thanks to a technique called brainbow –a word game that mixes the English terms brain (“brain”) and rainbow (“rainbow”) – and that originally allowed neurons to be stained with multitudes of different colors to visualize how these nerve cells behave, one by one. It is achieved by inserting genes that regulate the manufacture of fluorescent proteins. Now geneticists have succeeded in applying the brainbow method to skin cells and cornea, and have renamed it skinbow .
By adding all the combinations of green, red and blue proteins (the primary colors of light), the transgenic zebrafish can randomly emit about 5,000 different color hues in a process similar to that used by television sets, although only 70 colors can be detected individually under the microscope. Enough to distinguish a cell from its neighbor. With this intervention, experts will try to study in real time how skin tissue regenerates after suffering an injury or what happens at the cellular level when a fin is amputated.
Photo: section of fluorescent zebrafish skin under a microscope. Credit: Chen et al. / Developmental Cell 2016
