SOMETIME soon, genomics pioneer Craig Venter is expected to announce the creation of the first 鈥渟ynthetic鈥� organism. He has hinted that his team has made a 鈥渕inimal鈥� bacterial genome from its chemical building blocks (see 鈥淚nterview: Craig Venter鈥�), and the researchers have already transplanted the genome of one bacterial species into another. A little tweaking, and they should be able to take a Mycoplasma bacterium and replace its DNA with their artificial genome. Hey presto: synthetic life!
The announcement of this new species, dubbed Mycoplasma laboratorium, is sure to spark fierce debate. Has Venter crossed a fundamental line by 鈥減laying God鈥�? To what uses might organisms built from synthetic DNA be put? Will they pose dangers to our health, or to the environment? And might the technology be used to create bioweapons?
Answers to the first question depend on one鈥檚 religious perspective, but the others are issues of science and its regulation. We ought to debate them now, whether or not Venter succeeds in his quest, because the ability to synthesise stretches of DNA millions of base pairs long is poised to transform genetic engineering.
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Until now, genetic engineers have mostly been content to take small pieces of DNA from one species and transfer them to another to make a useful protein. Adding the gene for human growth hormone to the bacterium Escherichia coli, for example, produced a drug to treat congenital dwarfism.
Synthetic biology is starting to let researchers go much further. They can design and build sophisticated genetic circuitry to control complex biochemical pathways, creating organisms capable of novel tasks (New Scientist, 20 May 2006, p 43). Venter wants to design microbes that can end our reliance on fossil fuels by turning cellulose into ethanol or even making hydrogen. And while he intends to plug his genetic circuits into the entirely synthetic genome of M. laboratorium, others are adding synthetic DNA to genomes of natural species. Both strategies hold huge promise, but also entail risks.
Already, the ability to synthesise smaller viral genomes has highlighted the danger of designer bioweapons (New Scientist, 12 November 2005, p 8). Evolutionary history also points to the potential environmental hazards of creating microbes with radically novel metabolic pathways. When the first photosynthetic bacteria emerged 3.5 billion years ago, the oxygen they pumped out was toxic to most other contemporary life forms.
But let鈥檚 not be alarmist. The chances that Venter or competing groups will accidentally spawn a killer plague or wreck the environment are small. In fact, there are reasons to think that Venter鈥檚 creation will pose fewer risks than part-synthetic versions of natural species. Mycoplasma are stripped-down bacteria, reliant on the host organisms in which they live. Venter鈥檚 synthetic genome has been further gutted to leave a minimal set of genes. It can survive under ideal lab conditions, but a fugitive M. laboratorium is unlikely to last long.
Similarly, if a modified E. coli containing large chunks of designer DNA escaped the lab it would probably fare poorly in the Darwinian struggle for survival. But we cannot be sure. We need to look again at procedures for ensuring lab, public and environmental safety 鈥� and at security measures to keep dangerous DNA sequences out of the hands of those who may want to turn them into weapons.
鈥淎 bug containing large chunks of designer DNA would probably fare poorly in the Darwinian struggle for survival鈥�
Pioneers in the field have been thinking about these issues for some time. Many contributed to the report released this week by the J. Craig Venter Institute, the Massachusetts Institute of Technology and the Center for Strategic and International Studies, a security think-tank in Washington DC. It assesses the likely effectiveness of various measures to minimise risks, weighing them against the costs and whether they will impede research.
Among the measures suggested to plug the biggest gaps in the most cost-effective way are the compilation of a biosafety manual for synthetic biology labs and a requirement that commercial DNA suppliers screen their orders for potentially dangerous sequences. It is a good starting point for a debate that should begin now, and continue after the furore that will inevitably greet Venter鈥檚 announcement dies down.
