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ngin - Norfolk Genetic Information Network
 
 


The following article by the molecular pathologist Dr Michael Antoniou is taken from  LIVING EARTH: The Magazine of the Soil Association.  A longer version of this article with more technical detailcan be obtained by sending a s.a.e. to the Soil Association, 86 Colston Street, Bristol, UKBS1 5BB     soilassoc@gn.apc.org


Breaking the chain
 

Genetic engineering is a world apart from traditional breeding methods, despite claims to the contrary, says Dr Michael Antoniou. It is unpredictable, unstable and dangerous and the risks are not worth taking.


 


The Soil Association’s rejection of the use of genetic engineering in agriculture as simply having "no place in organic food and farming" is justifiable purely as a matter of principle. Genetic engineering (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 genetically engineered crops will result in less dependence on agro-chemicals 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 safe, more precise and a 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. Thc aim of this article is to assess the validity of this claim from a technical viewpoint focusing in particular on plants and animals.
 

GENES AND GENETICS

Genes, which we and every other creature on earth inherits from its parents, are 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. Physically, genes are discrete units of DNA. These DNA strands can be likened to a long string of pearls where each pearl, representing a gene, occupies its own special place in the "necklace" which is vital for its 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. Put simply, each gene has its own set of sophisticated on-off switches to drive its 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 arc interdependent upon each other for survival and growth, no gene works in isolation from all other genes. Genes are arranged along the DNA in groups, or 'families'. Thc 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 affect the function of genes in other groups of genes. Genes and the proteins that they make, have also 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 the integrity of life as a whole.
 

A NATURAL EXTENSION?

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 genetically engineered (transgenic) plants and animals are produced.

All genetically engineered plants start out life as individual or groups of cells growing on plastic dishes in the laboratory. The foreign genes are then either 'shot' into these plant cells with a 'gene gun' or introduced by infection into the cells with special GE bacteria. Finally, by changing the conditions under which the plant cells are growing on the dishes, they clump together and 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 gene.

The generation of transgenic animals is a no less artificial procedure.

Firstly, female animals are injected with fertility hormones to stimulate them to produce lots of mature eggs. They are then mated, killed and the fertilised eggs removed. These eggs are then injected, using a very fine needle, with the genes one wishes to engineer into the animal. The DNA injected eggs are returned to the womb of a surrogate mother where they complete their development and are born in due course.
 

NO-HOLDS BARRED

GE is a no-holds-barred technology. Using the procedures we just discussed, 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. In addition, the newly introduced gene units are composed of artificial mixtures of genetic material.  An example which illustrates the extreme combinations 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. However, the fish anti-freeze gene has to first be joined to the cauliflower virus genetic switch to allow it to turn on and work in its new host. (The fish genetic switch naturally only works in the fish). Transgenic crops containing genes from viruses, bacteria, animals as well as from unrelated plants have been generated.
 

INHERENT  UNPREDICABILITY

Clearly genetic engineering 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 tcchnique. Once injected into the cells of the organism, the introduced gene is randomly incorporated ('spliced') into the DNA of its new plant or animal host. 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 or 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 or the presence of the wrong protein 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 its new host as it does in its 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 its new hosts where it will now be surrounded by plant 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.
 

TECHNOLOGY OF THE FUTURE

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.

Clearly these procedures are worlds apart when compared to cross fertilisation between closely related species.

The totally artificial nature of GE does not automatically make it dangerous. It is the imprecision in the manner by which genes are combined and the unpredictabilityin how the introduced gene will interact within its new environment which results in uncertainty. The balanced gene functions that have evolved together and which are preserved with traditional methods, are sacrificed in the unpredictable science of genetic engineering. So from the standpoint of the fundamental principles of genetics and the limitations in the technology, GE is neither more precise nor a natural extension of traditional cross breeding methods. If anything the opposite would appear to be true.  GE foods therefore pose new and unique safety considerations both in terms of health and to the environment.

The availability of safe, sustainable, natural methods of breeding and husbandry utilising the many thousands of different varieties of any given food crop, makes the risks associated with GE foods simply not worth taking. These risks are even less acceptable when one takes into account the fact that once released into the envlronment, genetic mistakes or pollution cannot be recalled, cleaned up or allowed to decay like agrochemicals or a BSE epidemic, but will be passed on to all future generations indefinitely.
 
 

Dr  Michael Antoniou, is a senior lecturer in molecular biology at one of London’s leading medical schools ond has 17 years experience in the use of genetic engineering leading to clinical applications.
 


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