Scientists create first 'synthetic cell'

Scientists have created the first cell controlled by a human-made genome - a controversial step toward what is widely referred to as artificial life.

A team from the J. Craig Venter Institute in Rockville, Md., announced on Thursday it had created a synthetic bacterial genome that is a copy of an existing genome, though with added DNA sequences that "watermark" the genome to distinguish it from a natural one.
The scientists then transplanted the synthetic genome into a different bacterium to create what they call a "synthetic cell," although technically only its genome is synthetic.

(A computer-generated representation of a strand of DNA. )

The eventual goal is to build new organisms that work in ways that differ from what nature intended, such as custom-made bacteria designed for biofuel production or environmental cleanup.

The study was published online Thursday in the peer-reviewed the journal Science .

"This is the first synthetic cell that's been made, and we call it synthetic because the cell is totally derived from a synthetic chromosome, made with four bottles of chemicals on a chemical synthesizer, starting with information in a computer," J. Craig Venter, the institute's founder and a leading scientist in synthetic biology, said in a release.

"This becomes a very powerful tool for trying to design what we want biology to do. We have a wide range of applications [in mind]."

Specific examples include designing algae to capture carbon dioxide and make new hydrocarbons that could go into refineries, or speeding up vaccine production.

While scientists have been able to transplant genes from one species to another for several years now, the Venter team transplanted an entire synthetic genome from one bacterium to another.

The scientists synthesized the genome of a type of bacteria called Mycoplasma mycoides and transplanted it into a related species of bacteria called Mycoplasma capricolum. The new genome then "booted up" the recipient cells in much the same way that a computer's operating system makes the computer work.
"Once the new chromosome is in that recipient cell, all the traces of that recipient species disappear within a few rounds of replication," says Venter, speaking to Science.

Although 14 genes were deleted or disrupted in the transplant bacteria, they still looked like normal M. mycoides bacteria and produced only M. mycoides proteins, the authors report.

The transplantation was not a straightforward operation, because current technology only allows scientists to assemble relatively short strings of DNA letters at a time.

To get around this problem, the Venter team inserted the shorter sequences they'd created into yeast, whose DNA-repair enzymes linked the strings together. They then transferred the medium-sized strings into E. coli and back into yeast. After three rounds of assembly, the researchers had produced a genome over a million base pairs long.

Venter says he is confident his team can keep the engineered genome in the lab because neither species of bacteria grow independently. Mycoplasma mycoides exists in goats, and sometimes cattle, and can cause mastitis, or inflammation of breast tissue.

"We have not tested to see whether this still would still grow in goats. Unless a goat walks into the laboratory, or somebody walks out of our laboratory and injects a goat, we're probably pretty good with containment," says Venter, stressing that his company has sought and received ethical reviews of its research.

CBC News