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Lab remakes species by total DNA exchange

The Baltimore Sun

Scientists at a Rockville biotechnology institute say they have completely replaced the DNA of one bacterium with that of another, effectively changing its species.

The experiment could open the door to production of artificial organisms whose original genetic material is replaced entirely by man-made DNA, the researchers said. That way, they believe, they can program bacteria to produce useful metabolic products, such as new biofuels.

Critics said the experiment raises concerns about the unknown risks of artificial organisms and the emerging science is too loosely regulated.

The scientists were led by J. Craig Venter, a biotech maverick and entrepreneur who once competed with the publicly funded Human Genome Project to map the human genome, a race that ended in a tie in 2003.

In his team's experiment, Venter said, the bacterium that received new DNA began acting like the donor species, which confirmed the success of the transfer.

"This is equivalent to changing a Macintosh computer to a PC by inserting a new piece of software," he said Wednesday in a telephone news conference.

The findings of the experiment, which took place at the J. Craig Venter Institute, were published online yesterday by the journal Science.

Venter's group and others are trying to determine the minimum number of genes that bacteria need to survive. Then, separately, they want to construct simple, man-made DNA in the lab so scientists could add desirable genes to the bare-bones synthetic DNA and use that to replace the bacteria's DNA.

Such bacteria, the theory goes, would follow human marching orders and be useful in fields such as medicine and energy production.

Genetically modified organisms are already used to manufacture drugs and other products, but they're produced by changing only small sections of DNA. In contrast, whole genome transplantation might allow scientists to make more significant genetic changes to bacterial DNA or design artificial organisms from scratch.

Venter said wholesale replacement of an organism's genome with synthetic DNA might avoid the need to disable undesirable genes that interfere with the cells' desired function. It would also allow scientists to build DNA from the ground up, he said, giving them more control over cellular function.

Venter acknowledged that the research is still in its early stages but said the results were promising - particularly as the experiment involved swapping DNA isolated from all other cellular material. Scientists worry that such "naked" DNA might not flourish in a new cell because it would lack certain helper proteins.

"We want to be sure the DNA itself could boot up the new cell," Venter said. "The fact that we can do this with naked DNA and that it doesn't require accessory proteins is a huge enabling step for this field."

Venter and the company he founded, Synthetic Genomics, have applied for patents related to the creation of artificial organisms. His company signed a contract with London oil giant BP this month to research new clean energy technologies.

Arthur Caplan, chairman of the department of medical ethics at the University of Pennsylvania, saw both promise and peril in Venter's work.

"The techniques Venter has perfected are going to result in some very important products," he said. "We're not there yet, this is a proof of concept."

But he cautioned that attempts to create synthetic organisms raise some ethical concerns. "We don't really have in place an oversight system for this type of technology," he said. "We need to ensure that microbes aren't going to escape into the air or down the drain. We also need to be alert to the fact that this technology can make bad bugs rather than useful bugs."

Eckard Wimmer, a genetic researcher at the State University of New York at Stony Brook, said concerns about the possibility of creating artificial life might be premature, fueled by Venter's high profile rather than real risk.

Wimmer said Venter's team has "superb scientists," but his "knack for blowing his horn loudly" could cause unwarranted alarm.

Bloomberg News Service contributed to this article.

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