With genes from bacteria, jellyfish and coral

Nov 1, 2007 10:40 GMT  ·  By

By creating a brain like a rainbow, scientists were able to study the brain's functions like never before. The "Brainbow", developed at Harvard University, is a genetic engineering that has inserted fluorescence genes from coral, jellyfish and bacteria, making mice brains shine in a curious array of colors betraying complex neuronal connections. The study is published in the Nov. 1 issue of the journal Nature.

The most employed technique for tracking neurons was developed since 1873 by Camillo Golgi, the famous Italian physician, but it colors just a few neurons at a time, while Brainbow hints hundreds of brain cells at a time in about 90 various colors. The colorful paintings are amongst the most sophisticated pictures of neuronal connections ever obtained.

"We've already used Brainbow to take a first peek at the nervous system of mice, and we've observed some very interesting, and previously unrecognized, patterns of neuron arrangement. As far as understanding what we're seeing, we've only just scratched the surface." said co-author Joshua Sanes.

Brainbow uses a similar method to color generating on a computer or TV screen. "In the same way that a television monitor mixes red, green and blue to depict a wide array of colors, the combination of three or more fluorescent proteins in neurons can generate many different hues," said co-author Jeff Lichtman.

Still, Brainbow must operate on cyan, red and yellow gene pigments, not the wavelengths operated by the retina (blue, red and green). The red gene pigment was achieved from coral, while the cyan and blue pigments from jellyfish. "Each cell would play the slot machine and be attributed a different color," co-author Jean Livet told LiveScience. "In order for the color genes to be expressed, however, the mice cells must also contain another gene, called Cre." said Livet.

Cre was selected from bacteria. The gene works like "the hand pulling the lever over and over again," Livet said. Cre can be expressed in various body parts at different developmental stages. "The system can be tuned to whatever you want. The colors are only visible when viewed under fluorescent light, so the Brainbow-ed brains still look like normal mice brains, or normal transgenic mice brains, I should say.", said Livet.

Still, the Brainbow technique requires several hundred thousands dollars fluorescent microscopes in order to be used and works only on transgenic animals. "It's not like the Golgi stain, where you can just look through a normal microscope. With the Golgi stain, you can do everything, including humans,"" said Livet.

But Brainbow delivers much more information on the brain. "You can see how cells interact together. Instead of having a vision of just one cell within a circuit, you have a vision of the circuit itself.", Livet added.