Article published originally in "Living Earth"
(Editing with bold and italics has been done by the editor of this website in order to emphasize key sentences. Also long paragaphs found in the original version have been split up for better legibility)

by Dr Michael Antoniou, senior lecturer in molecular biology at one of London's leading medical schools and 17 years experience in the use of genetic engineering leading to clinical applications.

The Soil Association's rejection of the use of genetic engineering (GE) in agriculture as simply having "no place in organic food and farming" (Living Earth, Jan. '97), is justifiable purely as a matter of principle. GE represents an extension of intensive, industrial agriculture and therefore reinforces environmentally damaging, non-sustainable husbandry. Evidence already exists which demonstrates that the claims that GE crops will result in less dependence on agrochemicals are, in the medium to long term, unfounded.

The greatest claim of those who endorse the use of GE in agriculture, is that it is a safe, more precise and natural extension of traditional cross breeding methods for generating novel varieties of crops and farm animals. It is said that this new technology simply gives nature a helping hand with something that would happen anyway. The aim of this article is to assess GE in agriculture from a technical and basic genetics viewpoint focusing in particular on plants and animals. We will see that technically speaking, the use of GE in agriculture is a crude and imprecise technology which bears no resemblance to traditional breeding methods for producing new varieties of crops and farm animals. Given this imprecision, the outcomes of using GE in food production both in terms of potential ill health and negative environmental impact, are far from certain. There would therefore also appear to be good scientific grounds for questioning the validity of using GE in agriculture especially when there are safe alterna tives available.

Genes are discrete units of DNA. They are the blueprints which carry the information for the tens of thousands of proteins which act as the building blocks of all the structures and functions (biochemistry) that constitute the body of any organism from bacteria to humans. DNA can be likened to a long string of pearls where each pearl, representing a gene, occupies it's own special place in the "necklace" which is vital for it's correct function. Genetics, the study of genes, has two basic components. Firstly, there is the information content of each gene; that is, what gene carries the blueprint for which protein. Secondly, genetics has taught us that the activity or expression of each gene is extremely tightly controlled or regulated. Put simply, each gene has it's own set of sophisticated on-off switches to drive it's expression ensuring that the correct protein and therefore appropriate structure and function, is present in the right place, time and quantity in the body.

Just as all forms of life are interdependent upon each other for survival and growth, no gene works in isolation from all other genes. The latest discoveries tell us that genes are arranged along the DNA in groups or "families". The function of a given gene in a group is dependent on all the other genes that are present within the same family. Furthermore, the genetic activity in one family of genes can effect the function of genes in other groups of genes. It is also clear that genes and the proteins that they give rise to, have co-evolved together to form an extremely intricate, interconnected network of finely balanced functions the complexities of which we are only just beginning to understand and appreciate. Such tight control of gene activity means you will never find liver functions in your brain or leaf specific processes in the fruit and vice versa! In addition, Nature has also evolved mechanisms whereby cross breeding can only take place between very closely related species. With traditional breeding methods, different variations of the same genes in their natural context (within the necklace of pearls) are exchanged. This preserves tight control and complex interrelationships between genetic and protein functions that are vital for integrity of life as a whole.

In order to assess the validity of the claim that GE represents a natural extension of traditional breeding methods, it is important to know how GE ("transgenic") plants and animals are produced.

As an example, let us see how the herbicide resistant, GE soya was generated. The objective here was to introduce into the soya plants a gene from a common soil bacterium which would allow it to survive when sprayed with the herbicide Roundup. Clearly you cannot "cross" a bacterium with a plant.

Therefore, the first step was to grow cells from soya bean plants on plastic dishes in the laboratory. Now, in order to allow the bacterial gene to be able to work once introduced into it's new plant host, it had to be linked to a genetic switch combining parts from a cauliflower virus and petunias. (As we discussed above, the bacterial gene's own switch will only work in the bacteria from which it came). This combination of cauliflower virus, petunia and bacterial DNA was then introduced into the soya bean cells growing on the dishes in the laboratory using a procedure known as "biolistics" which employs a device called a "gene gun". In this technique, tiny spheres of gold or tungsten are coated with the DNA one wishes to introduce into the plant cells. These DNA-coated metal particles are then shot at the plant cells using the gene gun at high speed. As a result some of these metal beads enter inside the plant cells carrying the new DNA with them.

Unfortunately from the point of view of the plant biotechnologist, the efficiency with which the new DNA is taken up by the soya bean cells on the dish is very low. Most of the cells don't take it up at all. So the key is to find those few cells among the many millions on the dish which have taken up the DNA. This is done by using another genetic trick. The introduction of the bacterial gene into the soya bean cells for herbicide resistance, was accompanied by a second gene which confers resistance to an antibiotic (called kanamycin). The soya bean cells were then treated with the antibiotic. The few cells which had taken up the herbicide resistance:antibiotic resistance "marker" gene combination survived and flourished whereas the majority of the cells which had not taken up these genes were simply killed by the antibiotic.

Finally, by changing the conditions under which the soya bean cells are grown, the cells clump together to form what is called a callus which in turn starts to put down roots and sprout green shoots. These little "seedlings" are then potted so as to grow into fully mature plants which will carry in all their cells (including those for reproduction; i.e. pollen etc.) the new bacterial gene. The plant which then displays the best agronomic performance, in this case resistance to herbicide, is then selected for further development (crossing to form new hybrids etc.).

The generation of transgenic animals is a somewhat simpler, but no less artificial procedure. Fertilised eggs are first removed from the animal of choice. These eggs are then injected with the genes one wishes to engineer into the animal. The DNA injected eggs are then returned to the womb of a surrogate mother where they complete their development and are born in due course.

Therefore, in marked contrast to traditional breeding methods, all transgenic plants and animals start life as individual or groups of cells growing on a plastic dish in a laboratory.

It is evident from the procedure we just described that with GE there are no holds barred. GE allows the isolation, cutting, joining and transfer of single or multiple genes between totally unrelated organisms circumventing natural species barriers. As a result combinations of genes are produced that would never occur naturally. Transgenic crops containing genes from viruses, bacteria, animals as well as from unrelated plants have been generated.

In the case of the herbicide resistant soya beans, the final outcome was the combination of genetic material from four totally unrelated organisms; a cauliflower virus, petunia, bacteria and soya. Furthermore, again as we saw in the case of the GE soya beans, the newly introduced gene units are composed of artificial combinations of genetic material.

Another example which illustrates the extreme combinations of genetic material that can be produced, is the introduction of the "anti-freeze" gene from an arctic fish (the sea flounder) into tomatoes, strawberries and potatoes in the hope of producing resistance to frost. As with the bacterial gene in the soya beans, the fish anti-freeze gene is joined to the cauliflower virus genetic switch to allow it to turn on and work in it's new host. (The fish genetic switch naturally only works in the fish). All this is in turn coupled to an antibiotic resistance marker gene to allow selection of the newly transformed plants.

Clearly GE represents a great technological advance. However, as we have already discussed, genes have evolved to exist and work in families. Therefore, the claim that the reductionist approach of GE which moves one or a few genes between unrelated organisms, is a precise technology is highly questionable.

Furthermore, the generation of transgenic plants and animals is currently an imperfect technique. Once injected into the cells of the organism, the introduced gene is randomly incorporated ("spliced") into the DNA of it's new plant or animal host.

In fact, the manner in which GE animals and plants are produced, always selects for the splicing of the foreign gene into regions of the host DNA where other natural genes are trying to work. Given the interdependence of gene function within any grouping of genes, this random splicing of the foreign gene into the host DNA will always result in a disruption in the normal genetic order in the "string of pearls". Therefore, GE of animals and especially plants, always results in a loss, to a lesser or greater degree, of the tight genetic control and balanced functioning which is retained through conventional cross breeding.

With GE, host genes can be silenced (inactivated) or inappropriately switched on resulting in either a deficiency in a given protein(s) or the presence of the wrong protein(s) in the wrong place or in the wrong quantity or all these combined.

In addition, it is also assumed that the introduced gene and the protein that it makes, will behave in exactly the same way in it's new host as it does in it's native environment which frequently will not be the case. As discussed above, gene and protein functions have evolved over millions of years to work together in any given organism. The anti-freeze gene/protein in the arctic sea flounder has evolved to work together with the other genes/proteins in this fish. It is purely an assumption that it will work in exactly the same way with no unwanted side effects in it's new hosts where it will now be surrounded by plant proteins!

These effects combine to produce a totally unpredictable disturbance in host genetic function as well as in that of the introduced gene. The resulting disturbance in biochemical function can unexpectedly produce novel toxins, allergens and reduced nutritional value.

The proponents of the use of GE in agriculture argue that mankind has been selecting and manipulating plant and animal food stocks for millennia and that this new technology is simply the next stage in this process. However, we have seen:

• Technically speaking, GE and traditional breeding methods bear no resemblance to each other.
• GE plants and animals start out life in a laboratory culture dish.
• GE employs totally artificial units of genetic material which are introduced into plant and animal cells using chemical, mechanical or bacterial methods.
• GE always results in disruptions to the natural order of genes within the host DNA.
• GE also brings about combinations of genes that would never occur naturally.

[Thanks to Dr Michael Antoniou and the Soil Association <soilassoc@gn.apc.org> in UK for whose publication "Living Earth" this article was written.]

Published at this website with the permission of the author.