Synthetic Life May Reveal Origins of Natural Life

Scientists have constructed the genome of the bacterium Mycoplasma mycoides from more than 1,000 sections of pre-assembled units of DNA

After he announced the creation of the first organism with a fully synthetic genome last Thursday, Craig Venter, founder of the genomics research institute that bears his name, went on to talk about how this breakthrough will benefit industries like pharmaceuticals, energy and materials.

In his explanation of the methods used to create the synthetic bacterium, Venter highlighted an important use for synthetic organisms: research. Like living test tubes, bacteria created by scientists could serve as controlled platforms for experiments by reducing the complexity that obscures the workings of many biological systems.

This work could lead to staggering findings in two major ways. First, cells with synthetic genomes could allow scientists to essentially snip out the complexities of living cells leaving only the simpler parts. This would give researchers a better way to untangle the enormously complicated interactions that occur in natural cells, and could help unravel the secrets of baffling diseases like cancer.

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"People are really pretty much stuck about what actually happened on our planet to make new life forms," said David Fitch, an associate professor of biology at New York University. "There have been lots of experiments that propose different ways new living systems could have arisen, and maybe some of these issues could be addressed by synthesizing new genomes with very simple kinds of pathway structures."

In a cell with a synthetic genome, scientists could eliminate some of these intersections. For instance, scientists studying how the interactions between two pathways cause a disease could design a bacterium that generates only those pathways, said T. Martin Embley, a professor of evolutionary molecular biology at Newcastle University in England. By using a simplified synthetic organism instead of a vastly more complex natural bacterium, researchers could design more elegant experiments with clearer results, Embley told LiveScience.

Some pathways determine how the cells in multicellular organisms naturally develop from unspecified cells into those with specific functions. Cells with synthetic genomes could shed light on those processes too, Fitch said. When multicellular organisms mature, waves of signaling molecules ebb back and forth across the developing embryo, and the interaction of those signals tell cells whether to become hairs, nerves, shells, flippers or wings.

Alternatively, rather than creating never before seen cells, scientists could create organisms that went extinct millions of years ago by mathematically deriving the genome of the extinct creature from the genomes of its living descendants, said Martin Kreitman, a professor of molecular biology at the University of Chicago. Animating an extinct creature through synthetic biology would allow scientists to measure cell properties not immediately apparent from the genome itself, such as growth rates and temperature resistance.

Scientists could reconstruct the genome of extinct creatures by looking at the DNA of living descendents, and then assembling the extinct creature's genome and inserting it into an "emptied" cell using the same technique as the Venter Institute team. These synthetic organisms could provide scientists with valuable data about the environment they lived in, Kreitman told LiveScience. For example, probing the temperature and pH tolerance of an extinct bacterium could teach scientists about the chemistry of an ancient ocean, Kreitman said.

In biology, in vitro experiments are those done in a test tubes, while in vivo experiments are done in living organisms. Often, reactions that work well during in vitro experiments progress differently during in vivo experiments, thanks to the influence of other chemicals in an organism. This can frustrate the process of scientific discovery. For example, a drug that treats diseased cells in a test tube might not actually work to cure a person who has that disease.

Stuart Fox currently researches and develops physical and digital exhibit experiences at the Science Liberty Center. His news writing includes the likes of several Purch sites, including Live Science and Live Science's Life's Little Mysteries.