Reposted from the NYTimes:
http://www.nytimes.com/2007/07/08/weekinreview/08wade.html?ref=science

FORGET genetic engineering. The new idea is synthetic biology, an effort by engineers to rewire the genetic circuitry of living organisms.

The ambitious undertaking includes genetic engineering, the now routine insertion of one or two genes into a bacterium or crop plant. But synthetic biologists aim to rearrange genes on a much wider scale, that of a genome, or an organism's entire genetic code. Their plans include microbes modified to generate cheap petroleum out of plant waste, and, further down the line, designing whole organisms from scratch.

Synthetic biologists can identify a network of useful genes on their computer screens by downloading the gene sequences filed in DNA data banks. But a DNA molecule containing these various genes and their control elements would be a chain of hundreds of thousands of DNA units in length. Though human cells effortlessly duplicate a genome of three billion units, the longest piece of DNA synthesized so far is just 35,000 units long.

Scientists at the J. Craig Venter Institute in Rockville, Md., hope to take a giant stride in synthetic biology by creating a piece of DNA 580,076 units in length from simple chemicals, chiefly the material that constitutes DNA's four-letter chemical alphabet. This molecule would be an exact copy of the genome of a small bacterium. Dr. Venter says he then plans to insert it into a bacterial cell. If this man-made genome can take over the cell's functions, Dr. Venter should be able to claim he has made the first synthetic cell.

Such an achievement could suggest some new plateau has been reached in human control of life and evolution. But Dr. Venter's synthetic genome will probably be seen to represent a feat of copying evolution's genetic programming, not of creating new life itself.

Synthetic biologists, as they survey all the new genes and control elements whose DNA sequences are now accumulating in data bases, seem to feel extraordinary power is almost within their grasp.

"Biology will never be the same," Thomas F. Knight of M.I.T.'s Computer Science and Artificial Intelligence Laboratory wrote recently in describing the new engineering discipline he sees as emerging from it.

Adherents of the new discipline held their third annual conference last month in Zurich but their creations are still at the toy rocket stage. A dish of bacteria that generates a bull's eye pattern in response to the chemicals in its environment. A network of genes that synthesizes the precursor chemical to artemisin, an anti-malaria drug. "The understanding of networks and pathways is really in its infancy and will be a challenge for decades," says James J. Collins, a biomedical engineer at Boston University.

That hasn't stopped synthetic biologists from dreaming. "Grow a house" is on the to-do list of the M.I.T. Synthetic Biology Working Group, presumably meaning that an acorn might be reprogrammed to generate walls, oak floors and a roof instead of the usual trunk and branches. "Take over Mars. And then Venus. And then Earth" —the last items on this modest agenda.

Most people in synthetic biology are engineers who have invaded genetics. They have brought with them a vocabulary derived from circuit design and software development that they seek to impose on the softer substance of biology. They talk of modules — meaning networks of genes assembled to perform some standard function — and of "booting up" a cell with new DNA-based instructions, much the way someone gets a computer going.

The first practical applications of synthetic biology may not be so far off. "The real killer app for this field has become bioenergy," Dr. Collins says. Under the stimulus of high gas prices, synthetic biologists are re-engineering microbes to generate the components of natural gas and petroleum. Whether this can be done economically remains to be seen. But one company, LS9 of San Carlos, Calif., says it is close to that goal. Its re-engineered microbe "produces hydrocarbons that look, smell and function" very similarly to those in petroleum, said Stephen del Cardayre, the company's vice president for research.

Synthetic biologists are well aware that, like any new technology, theirs can be used for good or ill, and they have encouraged open discussion of possible risks at their annual meetings.

One possible danger is bioterrorism. According to a report in Science, Blue Heron Biotechnology, a DNA synthesis company, has already received requests, which it rejected, for DNA sequences encoding a plant toxin and part of the smallpox virus. Synthetic biologists hope that self-regulation will head off government supervision that could be expected to come in a field that has such potential for mischief.

Evolution continually refines its creations by means of the naturally occurring mutations in DNA that are the raw material of natural selection. This propensity to innovate may not be so welcome to synthetic biologists, who seek stable systems. But they hope to spot mutations with error-detection algorithms and then go back to the original cells. "You can think of it as a re-boot," said Ron Weiss, a synthetic biologist at Princeton.

Even if the mutation problem can be squelched, it remains to be seen how far synthetic biologists can wrest evolution's strange system to entirely different purposes and whether the human organism is one they will propose to debug and upgrade.