Far from playing God, the scientist Craig Venter is not even in the same playing field, writes Professor William Reville

The recent announcement by Craig Venter, the American scientific entrepreneur, that he had made a 'synthetic cell' naturally generated widespread attention. Comments such as 'revolutionary breakthrough' vied for attention with 'scientist plays God'. However, the truth is that Dr Venter has achieved a very significant technical feat that is also of philosophical importance, but no more.

Specifically, he made a copy of the genome (genetic make up) of a bacterium in the laboratory and inserted the copy into another bacterium, where it successfully took over the running of the host cell.

Scientifically this is what would be expected to happen in accordance with our understanding of the molecular biology of the cell, but it had not been practically demonstrated before. Venter's proof of principle is a first step on a very long road towards the design and construction of new useful organisms radically different from the spectrum of organisms that undisturbed nature has produced. However, many scientists would argue that this end could be achieved more easily using conventional genetic engineering techniques.

To be fair to Venter (pictured right), he doesn't claim to have synthesised life - this claim was made by some over-enthusiastic media commentators. In order to credibly claim that you had created life you would have to make a living cell in the laboratory starting out only with atoms of the basic elements that constitute life, principally carbon, hydrogen, oxygen, nitrogen, phosphorous and sulphur, using only laboratory chemical and physical methods, and without relying on pre-existing life to carry out any of the steps for you.

Copied

Venter certainly did not create life - he copied life, and his entire method depends on pre-existing living cells. So, far from 'playing God', Venter is not even on the same playing field as God. I will illustrate this later in this article when I report on a recent scientific contest!

Venter made a copy in the laboratory of the genetic material present in the bacterium M. mycoides. This genetic material is built into a structure called the chromosome. Chemically the chromosome is made of a long string of units called nucleotides. There are 4 different nucleotides denoted by the letters A, T, G and C. The genetic information is coded in the sequence of these letters along the length of the chromosome. There are 1.08 million letters in the M. mycoides chromosome and Venter worked out their sequence in previous experiments.

You can buy bottles of the pure individual nucleotides (A,T,G,C) from chemical supply companies and you can chemically string them together, in lengths up to several hundred nucleotides long, in any sequence you like using a machine called a DNA synthesiser. In this way Venter first copied the entire M. mycoides chromosome piecemeal in individual 1,000 long nucleotide segments. He then gradually linked these segments together in the right order until he eventually had a copy of the entire M. mycoides 1.08 million nucleotide-long chromosome. Venter also inserted 'watermark' codes into the chromosome, including quotations from James Joyce. He then inserted this copy chromosome into another bacterium M. capricolum where it took over and ran the cell as the bacterium M. mycoides.

Synthesised

Every step of this procedure depends on pre-existing life. Firstly, the nucleotides (A,T,G,C) fed into the DNA synthesiser were either extracted from living cells or were synthesised using catalysts called enzymes extracted from living cells. Each nucleotide is a complex molecule composed of about 45 atoms.

Secondly, the higher order stitching together of the 1,000 long nucleotide segments of the chromosome was done by living cells - Venter inserted these segments into living yeast cells. Natural repair mechanisms in the yeast cells assumed that the inserted segments were fragmented chromosomes and 'repaired' them by stitching them together.

And, finally, when the copy chromosome was complete it was inserted into a living bacterial cell where it took over. This living host bacterial cell is a very complex and delicate organisation of molecular and supramolecular assemblies arranged in a precise manner, immersed in a fluid in which a complex mixture of many hundreds of chemicals are dissolved in precisely the right amounts and balance to support life, and all of this is surrounded by a delicate cell membrane.

Work will now begin, using Venter's technique, on designing chromosomes to direct microorganisms to do useful things. For example, Venter has been contracted by the Exxon corporation to design algae that will suck carbon dioxide out of the air and convert it into biofuel.

Another project will attempt to design bacteria that will 'gobble up' oil spills. However, such developments will surely be very slow. It is one thing to demonstrate that a copy of a natural chromosome works as well as the original. It will be quite another matter to get a chromosome to work that never existed naturally before.

Wrong

The difficulty here is illustrated by the work Venter just carried out. The first copy of the chromosome Venter made failed to 'boot up' the host bacterial cell when it was inserted. Careful examination showed that just one letter of the 1.08 million letters in the copy chromosome was the wrong letter. When this mistake was corrected, the copy chromosome worked! This is how delicately poised life is.

Venter's achievement was a technical tour de force. Nobody ever artificially assembled such a large chromosome before. Venter and his team of about 20 people took 10 years to complete this work at a cost of over 40 million dollars. It was also a philosophical milestone, practically demonstrating for the first time that an artificially constructed chromosome can take over a living cell just as software runs the hardware of a computer.

And, finally, is man now seriously rivalling God? The answer is no. I was recently invited to witness a confrontation between God and another scientist who is far more advanced than Craig Venter in his ability to create synthetic life. This scientist challenged God to a contest to determine who is the best at creating life. God agreed and invited the scientist to go first. The scientist bent down and scooped up a fist full of dust saying, ''First you take some dust''. God jumped in immediately and said - ''Hey, get your own dust!''

William Reville is Professor of Biochemistry at University College Cork.