2008 Nobel-Prize winner Roger Tsien, Ph.D., and his researcher team have engineered infrared-fluorescent proteins (IFPs) that can be used for whole-body imaging of small animals.
Tsien, professor of pharmacology, chemistry, and biochemistry at UC San Diego and a Howard Hughes Medical Institute investigator, was awarded the Nobel Prize for the development of green fluorescent proteins (GFPs) for use in biomedical research. While they are useful for reporting gene expression, they are limited in the imaging of living mammals. GFPs' short wavelengths do not allow light to penetrate far enough to allow inner cells in small mammals to glow.
"The development of IFPs may be important for future studies in animals–to find out how cancers develop, how infections grow or diminish in mice, or perhaps how neurons are firing in flies," said Tsien in a prepared statement.
First author Xiaokun Shu, Ph.D., of the UC San Diego School of Medicine's Department of Pharmacology and the Howard Hughes Medical Institute, coerced the phytochrome from the bacteria Deinococcus radiodurans to fluoresce. It is the first protein to glow in infrared and work in mouse models.
"IFPs express well in mammalian cells and spontaneously incorporate biliverdin, a green pigment that is present in humans and other mammals," said Tsien. Shu was able to coax the biliverdin-containing protein to fluoresce by removing the parts of the phytochrome that divert the energy of the light.
