Feature: The meaning of (artificial) life

J. Craig Venter and Hamilton O. Smith at the JCVI.

It was once widely believed that life differed fundamentally from non-life; the defining characteristic of life was the existence of some insubstantial vital force – an élan vital – for which no physical process could account.

The first blow to this theory was dealt by German chemist, Friedrich Wöhler, in 1828, when he synthesised urea in the lab, demonstrating that even ‘vital’ organic compounds were formed from the same lifeless building blocks as common inorganic compounds. Yet, urea alone isn’t alive.

It took a further 182 years for the notion of vitalism to finally be put to rest with a paper produced by the team at the J. Craig Venter Institute (JCVI), published in Science on May 20. As stated by Craig Venter during his press conference, the paper details the creation of the “first self-replicating species that we’ve had on the planet whose parent is a computer.”

Venter and his team, in the culmination of 15 years of toil, had synthesised an entire genome from “four bottles of chemicals”, assembled it, and transplanted it into a host cell of a different species, which then went on to replicate using the synthetic DNA as its blueprint. Noticeably absent from that blueprint was élan vital.

But how significant is this development? Despite the hyperbolic headlines that sprang up in the mainstream press announcing that we had, at last, created life by our own hand, the actual achievement was somewhat more modest. Venter’s team didn’t achieve abiogenesis.

They also didn’t build an organism entirely from scratch – the synthetic chromosome took occupancy in the cellular abode of an existing bacterium. And the genome they used was largely designed by nature, if assembled in a lab.

But what Venter’s team did achieve was a technical triumph in synthetic biology, says Dr Kirby Siemering, of the Australian Genome Research Facility. “It’s a major milestone in terms of being a proof of principle demonstration of the technology.”

And this technological breakthrough will have potentially far reaching ramifications for the burgeoning discipline of synthetic biology, with Venter, among others, hoping it will open the door to designer organisms with a manifold of uses, such as production of biofuels, vaccines, biologics and organisms for bioremediation.

Three steps to artificial life

The actual process to create the synthetic version of Mycoplasma mycoides, dubbed M. mycoides JCVI-syn1.0. was a three step affair, beginning with an excruciatingly accurate sequence of the bacteria in question.

In fact, it took two sequences of the 1.08 million base pair (bp) genome to achieve sufficient confidence in the accuracy, one a standard lab strain, the other a cloned version produced by the JCVI. The two sequences differed only at 95 sites, which is suggestive of the differences between the organisms rather than errors in sequencing, says Siemering.

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