Optogenetic control of bacterial genes (IMAGE) Rice University Caption Light-responsive bacteria fed to worms are visible in images of the worms' gastrointestinal tracts. Engineers programmed the bacteria to produce a red fluorescent protein called mCherry so they would be easy to see under a microscope. When exposed to green light, the bacteria also produce a green fluorescent protein called sfGFP, which causes them to glow green. When exposed to red light, they do not produce the green protein. Worms in the left column were treated with red light. Worms in the right column were treated with green light. Credit Image courtesy of Jeff Tabor/Rice University Usage Restrictions Must credit: "Jeff Tabor/Rice University" License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.