James E. Hayden
GFP Mouse and Offspring, 2003

Fluorescence photograph; Nikon CoolPix 990 digital camera; Illumatool LT-9900 light source with excitation at 470nm and a 515nm barrier filter; additional ambient light - tungsten source.

The Wistar Institute, Philadelphia, Pennsylvania, United States Green

Green Fluorescent Protein (GFP) has become an important part of biological investigations that requires non-invasive labeling of cells, especially in vivo. Derived from the jellyfish Aequorea victoria, GFP can be integrated directly into the DNA of a cell where it will naturally emit green fluorescence when excited with the proper blue wavelength. The fluorescence that is produced can then be used as a marker to follow a variety of biological events, from aging and cancer development to protein synthesis and xenotransplantation.

Researchers initially injected GFP-tagged spermatogonial stem cells into recipient male mice to see if the introduced cells would be viable for sperm production. All of the cells in mice produced from these stem cells then fluoresced, as shown by the adult mouse in the image (the emitted green light is blocked by hair, so only the parts of the mouse with little hair, like the tail, paws and ears, show green). With the GFP incorporated into its genome, the male mouse then passed the “green gene,” through normal Mendelian genetics, to its offspring. The mouse pup that inherited the gene fluoresces like its father, while the remaining siblings, who did not receive the gene with the GFP, do not. This image is the result of a combination of two original digital images, taken seconds apart..

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