Designer proteins aren't just for bacteria anymore. For the first time, scientists have engineered a whole animal to build its proteins with a synthetic amino acid. The early adopter is a microscopic worm known as Caenorhabditis elegans. Researchers had previously tweaked the genome of the Escherichia coli bacterium to code for 21 amino acids instead of the typical 20, and now another group has done the same with C. elegans. To track which of the worm's cells made proteins that utilized this extra, artificial building block, the team tagged it with a glowing cherry-red dye. And sure enough, cells that went synthetic glowed red, the researchers report this week in the Journal of the American Chemical Society. They now hope to create worms with artificial amino acids that can be controlled by light or specific chemicals: a toolkit that would allow researchers to switch specific cells or molecules on and off.
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