By Tamily Weissman, Harvard University
“Brainbow" mice are engineered with a gene that includes three different fluorescent proteins, but only one color is actually expressed from each copy of the DNA construct. Pairs of "incompatible lox sites" are nested around different portions of the gene, allowing for recombination to snip out different parts of the gene randomly. Depending on what DNA is excised, a different color results.
Image: Here individual neurons of the dentate gyrus, a layer of the hippocampus, project their dendrites to the outer layer, where they receive input from the cortex. Neurogenesis occurs inside the “V,” where neurons are born and then migrate outward toward the dentate gryus. (via Cell - Cell_Picture_Show-Brainbow2)