Heading for synthetic life?

A team of U.S. scientists has synthesised an entire bacterial genome and then produced living cells that relied on this genetic information. This was the first time a synthetic cell was made by starting with genetic data stored in a computer, declared Craig Venter who led the effort. His team has made major strides in recent years working on synthetic genomes. The Indian-born Nobel laureate, Har Gobind Khorana, carried out the first gene synthesis in the late 1970s. It involved stringing together some 200 bases, the chemical units that produce the four ‘letters' of the genetic code. By 2002, scientists in New York were able to produce infectious polioviruses from synthetic DNA about 7,500 bases long. The Venter team has now demonstrated the feasibility of assembling a genome that is over one million bases in length. It was then able to get the synthetic genome to work in another bacterium. However, as the team discovered, a change in just one base in a crucial gene was sufficient to stop the synthetic genome from functioning in a living cell.

But it is quite a stretch to speak at this stage of the production of synthetic life. The synthetic genome was based on the naturally occurring genome of the bacterium Mycoplasma mycoides (with certain modifications). Moreover, the genome, in order to function, had to be put into a living cell, not one that was artificially created. Dr. Venter “has not created life, only mimicked it,” commented Nobel laureate David Baltimore. It is much more likely that synthetic genomes will be used in the coming years to generate novel gene combinations. Scientists have long been able to modify genomes by inserting and deleting genes. Genetically engineered Bt-cotton plants, for instance, carry genes taken from soil bacteria. Several genes have been introduced into a bacterium so that it can produce the precursor of the anti-malarial drug artemisinin. Dr. Venter and his colleagues say that in the long run it would be better to design the entire chromosome from scratch than to make changes one by one in the genome. His group is planning to build an entire algal genome in order to make super-productive organisms that could take in carbon dioxide and spew out hydrocarbons. Inevitably, a technological advance that appears to tamper with the foundations of life arouses disquiet. Concerns have been expressed over the possibility of the technique being misused to produce dangerous pathogens and the artificially engineered organisms escaping into the wild and contaminating the natural gene pool. Governments and society need to find ways of maintaining oversight so that benefits of the technology are harnessed and its abuse prevented.