One of the first PR sound-bytes fed to the GM-wary UK public was that “scientists know exactly what they're doing”.
If this subliminal message of 'nothing can go wrong, so stop worrying yourself' wasn't reassuring enough, images were trotted out explaining that DNA sequences were simply snipped out of a cell (with scissors!) and popped into another one: clearly just another use of nature by humans, a simple extension of conventional breeding.
How truthful is this PR? Certainly, scientists can extract DNA from cells for study and to get ideas. Certainly, scientists can engineer precise DNA sequences and can force or smuggle these into living cells and can (sometimes) make them work. But “know exactly what they're doing”?
The scissors and bits of natural DNA being moved from cell to cell, cut-and-paste fashion, simply don't happen. Genetic engineers engineer genes: they construct a stretch of artificial DNA which they know might generate the novel protein wanted, and add bits to make it work and bits to stick it in place. If you want to know how 'natural' is the resulting gene compared with the real thing, consider the following:
1. Natural genes are messy
While artificial genes are put together in a neat, compact, linear form with no extra bits to subvert the protein produced, natural genes can be messy. A majority of natural genes exist in a modular format, whose parts may not even be near each other in the genome. This can create a bit of mix-and-match in protein production, so that a 'single' gene can vary its expression according to the immediate needs of the cell. One of the most extreme examples of this found to date is a fruit-fly gene which exists in so many separate pieces that it could, theoretically, generate 38,0016 different proteins.
Such intrinsic variability and flexibility in function is needed for the health of the cell and organism. None of these qualities can be engineered into man-made DNA.
2. Genes are a very small part of the story
The DNA of natural genes express natural RNA (molecules related to DNA) which, in turn, express natural proteins. There are huge stretches of non-gene DNA. These also express RNA, but the functions of these molecules are the regulation of the genes, their RNA and their proteins. Thus, in the living cell there exists an interaction between the genome (i.e. both genes plus non-gene DNA), all the RNA (i.e. both protein expressing plus regulatory), and the entire cellular protein turnover (i.e. creation, change and destruction) perpetually playing itself out.
Artificial genes, their artificial RNA, and their artificial protein can't participate in this, they can only dominate.
3. Genes change
Consider the following exciting scientific discoveries:
- if a natural gene is damaged, its function may be taken over by others;
- if one natural gene isn't enough, the genome may make more copies for itself;
- if a gene needs support in its function, it may convert other genes to a form similar to itself
- if a gene's function needs to be changed, it may have chemical markers attached to it;
- some areas of the genome mutate very readily.
Such intrinsic variability and flexibility in function is needed for the health of the cell and organism.
And that's all we know at the moment.
Given the ever-changing genome described above, do genetic engineers 'know exactly what they're doing'? Or, is that artificial piece of DNA which is invariable in structure and function, has to be forced or smuggled into the nucleus, and is uncontrollable by the cell nothing more than a carefully designed and constructed disease?
If you want to know more, treat yourself to a subscription for 'Science in Society' magazine, (see).
· Mae-Wan Ho, Death of the Central Dogma, Are Ultra-conserved Elements Indispensable?, Subverting the Genetic Text, To Mutate or Not to Mutate?, How to Keep in Concert, Science in Society, 24 Winter 2004