image: In a striking demonstration of targeted knockout rats, scientists used zinc finger nucleases to deactivate a green fluorescent protein (GFP) transgene, which causes the rats to appear green under ultraviolet lighting. The targeted knockout rat (left) does not exhibit this green fluorescence under the ultraviolet lighting. This image accompanied the research article "Knockout Rats via Embryo Microinjection of Zinc-Finger Nucleases," by A.M. Geurts et al appearing in the July 24, 2009, issue of Science. view more
Credit: Image courtesy of the Sigma-Aldrich Corporation and the Medical College of Wisconsin