A genome balloon for bursting

January 7, 2000

Before we succumb to yet more millennial angst, it is worth pausing to debunk the grandiose media claims concerning Craig Venter's paper in Science about creating life in a test tube (Soapbox, THES, December 24/31).

Despite these claims, we are still very far from being able to synthesise life in such a way. What Venter's group has done is to work out how many of the 500-odd genes in mycobacterium are essential for survival in the laboratory. It would seem that maybe as many as 200 of these genes are dispensable singly, defining a "minimal set" of genes essential for self-replicating life. This is no mean achievement, but falls well short of the media hype.

Venter is seeking ethical advice before pursuing what he sees as the ultimate dream of reductionist biology, namely synthetic life. To do this, one would have to synthesise copies of all 250-plus essential genes and string them onto a single chromosome. Then what? A set of DNA genes is like a software program - entirely functionless without a complex array of cellular machinery (the hardware) necessary to express that genetic information. To get your synthetic genome to work, you would have to insert it into a chromosome-free cell (presumably from our good friend mycobacterium). This particular program would have the unusual property of reproducing both hardware and software copies of itself, but you still need the hardware to kick-start the whole process.

What would this achieve? Even if it worked, you would only have a stripped-down version of mycobacterium, not a new form of life. You could reach the same endpoint far less controversially by sequentially deleting each of the "inessential" genes until you have a multi-mutant strain that can survive - at least in the laboratory. Bacterial geneticists do this sort of thing all the time, although not on such a large scale, so where is the big ethical issue?

Nearly 30 years ago, Khorana synthesised the first DNA gene (coding for a tRNA, if I remember correctly) in a test tube. Did anyone seriously believe that natural DNA possessed some sort of life force that would render a synthetic gene non-functional? I venture to suggest that Venter's proposed experiment would be a colossal waste of money. We already know that synthetic genes work in the same way as natural genes, so why bother with an entire synthetic genome?

This particular balloon needs pricking before it becomes yet more inflated with self-importance. Ethicists and religious leaders should refrain from bridling at any hint of human hubris usurping God's prerogatives as Creator and should instead treat the whole idea with the contempt it deserves.

Revd Dr David de Pomerai Senior lecturer in molecular toxicology University of Nottingham

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