Credit: Sarah Richardson/Johns Hopkins University

In a paper published in Nature yesterday, scientists at Johns Hopkins University share their success in modifying yeast (Saccharomyces cerevisiae), replacing parts of a yeast’s original chromosomes with synthetic fragments. This marks the first time a eukaryote with synthetic chromosomes has been successfully produced. Not only do these new yeast grow about as normally and healthily as normal yeast, but their genomes have been modified to be more stable than those of normal yeast.

The yeast are also engineered to have a novel evolution system, called SCRaMbLE (synthetic chromosome rearrangement and modification by loxP-mediated evolution). To create this system, the scientists added DNA sequences that are recognized by a specific enzyme. When the scrambling system is activated, the enzyme can randomly delete or rearrange genes, leading to yeast strains with various properties, such as different sensitivities to drugs and temperature. Many exciting questions can potentially be addressed with this new system. Scientists can use SCRaMbLE to probe into the evolution of the genome, addressing questions such as “How much of the genome is necessary for an organism to survive?” and “How much change in the genome is required to produce a new species?”

You can follow the latest developments from the Synthetic Yeast 2.0 Project at