Biomedicine Remaking Life Venter Institute researchers synthesize a genome. by Katherine Bourzac August 25, 2010 Sponsored by This stack of containers stores fragments of synthesized DNA that, when joined together, will form the entire bacterial genome. Each container has multiple wells, each of which contains copies of one section of the genome. Researcher Daniel Gibson combines a mixture of 10 consecutive DNA fragments with yeast cells that will stitch them together in the correct order, forming a circle of DNA. The stitching process is repeated until the yeast have assembled the complete genome. Multiple yeast colonies bearing synthetic DNA are smeared on petri dishes that are numbered to identify which part of the synthetic genome they carry. Multiple copies of the completed synthetic genome are encased in agarose gel inside this tube. The gel immobilizes and protects the fragile DNA loops. Researcher Li Ma mixes bacterial cells with copies of the synthetic genome. This must be done gently to avoid breaking the DNA. The mixture sits in an incubator for three hours. The cells have been treated to encourage them to fuse together; as they do, some of them encapsulate a synthetic genome that had been floating in the surrounding solution. A solution of cells, some of which contain the new genome, is mixed with a gel-based culture medium that contains an antibiotic. Then it’s poured into petri dishes and put into an incubator. Only cells containing the synthetic genome carry a gene that protects them from the antibiotic. The blue spots are colonies of bacteria now controlled by the transplanted synthetic genome.