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Genetic manipulation

Beoordeling 7.3
Foto van een scholier
  • Praktische opdracht door een scholier
  • 3e klas vwo | 2917 woorden
  • 12 juni 2001
  • 12 keer beoordeeld
  • Cijfer 7.3
  • 12 keer beoordeeld

If current trends continue, within a few years most of the foods we eat could be genetically engineered. Transnational corporations want us to believe that this food is safe, nutritious and thoroughly tested. Independent scientists, however, warn us that current understanding of genetics is extremely limited. They believe that this technology is flawed and carries inherent risks.

1. What is a gene?
All plants and animals contain millions of cells, each of which has a nucleus. Inside every nucleus there are strings of DNA, organised into structures called chromosomes. If all the DNA in the human body were unravelled it would reach the moon and back 8000 times! Each cell normally holds a double set of chromosomes, one of which is inherited from the mother and one from the father. One set of chromosomes from each parent combines when the sperm fertilises the egg (in the case of animals) or pollen fertilises the ovum (in the case of plants). The cell formed after fertilisation divides into two identical copies, each of which inherits this unique new combination of chromosomes. These embryonic cells then continue to divide and divide again. The inherited genetic material, carried in the chromosomes, is therefore identical in each new cell.

DNA is often described as a blueprint which contains all the essential information needed for the structure and function of an organism, and genes are described as the individual messages which make up the blueprint, each gene coding for a particular characteristic. Although this concept can be helpful as a tool for understanding, it runs the risk of reducing the organism to a machine, and viewing physiology as little different from a series of industrial processes. In reality, however, genes are very difficult to define and can only be understood within their context - a living organism.
No gene works in isolation. Genes are sequences of DNA which operate in complex networks that are tightly regulated to enable processes to happen in the right place and at the right time. This intricate network is informed and influenced by environmental feedback in relationships that have been evolving over millions of years. According to Barbara McClintock, who won the Nobel Prize in 1983 for her pioneering work in the field of genetics, the functioning of genes is 'totally dependent on the environment in which they find themselves'.

2. What is genetic engineering?
In traditional forms of breeding, variety has been achieved by selecting from the multitude of genetic traits that already exist within a species` gene pool. In nature, genetic diversity is created within certain limits. A rose can cross with a different kind of rose, but a rose will never cross with a mouse. Even when species that may seem to be closely related do succeed in breeding the offspring are usually infertile. For example, a horse can mate with an ass, but the offspring, a mule, is sterile. These boundaries are essential to the integrity of any species.
In contrast to traditional breeding, genetic engineering involves taking genes from one species and inserting them into another in an attempt to transfer a desired trait or character. For example, selecting a gene which leads to the production of a chemical with antifreeze properties from an arctic fish (such as the flounder) and splicing it into a tomato or strawberry to make it frost-resistant. It is now possible for scientists to introduce genes taken from bacteria, viruses, insects, animals or even humans, into plants.
It has been suggested that, because we have been modifying the genes of plants and animals for thousands of years, genetic engineering is simply an extension of traditional breeding practices. While it is true that the food crops we are eating today bear little resemblance to the wild plants from which they originated, it is clear that through this new technology organisms are being manipulated in a fundamentally different way.

3. How is this done?
There are a number of techniques in the genetic engineer's toolkit. Biochemical 'scissors' called restriction enzymes are used to cut the strings of DNA in different places and select the required genes. These genes are usually then inserted into circular pieces of DNA (plasmids) found in bacteria. The bacteria reproduce rapidly and within a short time thousands of identical copies (clones) can be made of the 'new' gene. There are now two principal methods which can be used to force the 'new' gene into the DNA of the plant that is to be engineered.

1. A 'ferry' is made with a piece of genetic material taken from a virus or a bacterium. This is used to infect the plant and in doing so smuggle the 'new' gene into the plant's own DNA. A bacterium called Agrobacterium tumifaciens which usually causes gall formation in plants is commonly used for this purpose.

2. The genes are coated onto large numbers of tiny gold pellets which are fired with a special gun into a layer of cells taken from the recipient organism, with any luck finding a hit somewhere in the DNA in the nucleus of the cells.

Genetically engineered (GE) animals and fish are produced by microinjection. Fertilised eggs are injected with new genes which will, in some cases, enter the chromosomes and be incorporated into the animal's own DNA.
Because the techniques used to transfer genes have a low success rate, the scientists need to be able to find out which of the cells have taken up the new DNA. So, before the gene is transferred, a 'marker gene' is attached which codes for resistance to an antibiotic. Plant cells which have been engineered are then grown in a medium containing this antibiotic, and the only ones able to survive are those which have taken up the the 'new' genes with the antibiotic-resistant marker attached. These cells are then cultured and grown into mature plants.
It is not possible to guide the insertion of a new gene with any accuracy, and this random insertion may disrupt the tightly controlled network of DNA in an organism.

4. Unpredictable effects
Current understanding of the way in which genes are regulated is extremely limited. Any change to the DNA of an organism at any point may well have knock-on effects that are impossible to predict or control.
· A gene coding for red pigment was taken from a maize plant and transferred into petunia flowers. Apart from turning white, the flowers also had more leaves and shoots, a higher resistance to fungi and lowered fertility.
The random insertion of a foreign gene may disrupt the tightly controlled network of DNA in an organism. The gene could, for example, alter chemical reactions within the cell or disturb cell functions. This could lead to instability, the creation of new toxins or allergens, and changes in nutritional value.
A piece of DNA taken from a virus or bacterium (called a 'promoter') is inserted along with the 'new' gene in order to 'switch it on' in its new host. Promoters, which often force genes to be produced at 10 to 1000 times normal levels, also have the potential to influence neighbouring genes. The promoter may, for example, stimulate a plant to produce higher levels of a substance which is harmless at low levels but which becomes toxic when present in higher concentrations.
· A yeast was genetically engineered for increased fermentation purposes. This led to the production of a metabolite called methyl-glyoxal in toxic and mutagenic concentrations.

5. Inadequate safety testing
of genetically engineered (GE) food
Many people became aware of GE food for the first time in 1996 when soybeans grown in the US were genetically engineered by Monsanto to be resistant to their best-selling herbicide Round-up. Over 40% of the US soybean harvest is exported. When the first consignment of GE soya arrived in Europe, it was already mixed in with the conventional harvest. The American Soybean Association rejected calls to segregate the GE soya on the basis that it was 'substantially equivalent' to ordinary soya.
The theory of 'substantial equivalence' has been at the root of international guidelines and testing of GE food. According to this principle, selected chemical characteristics are compared between a GE product and any variety within the same species. If the two are grossly similar, the GE product does not need to be rigorously tested on the assumption that it is no more dangerous than the non-GE equivalent.
From a scientific standpoint, the use of 'substantial equivalence' as a basis for risk assessment is seriously flawed, and cannot be depended on as a criterion for food safety. Genetically engineered food may contain unexpected new molecules that could be toxic or cause allergic reactions. A product could not only be 'substantially equivalent', but even be identical with its natural counterpart in all respects bar the presence of a single harmful compound.
· In 1989, 37 people died in the United States after consuming a food supplement called L-tryptophan that had been produced from GE bacteria. It was regarded as 'substantially equivalent' and passed as safe for human consumption.
GE foods already on the market in the US include corn, soybeans, potatoes, squash, tomatoes, chicory and papaya as well as milk and other dairy products from cows treated with a genetically engineered growth hormone (rBST).A variety of enzymes produced from genetically engineered microorganisms are used throughout the food processing industry. None of these foods have been subject to long-term safety studies or the kind of rigorous toxicological assessment that is applied to pharmaceuticals. Pharmaceuticals undergo up to 15 years of clinical trials which are still limited in their ability to assess unexpected problems; when pharmaceuticals are put on the market, 3% of them need to be withdrawn due to serious side effects.

6. Public concern
Numerous surveys have been conducted around the world in order to monitor public attitudes towards GE food. In industrialised nations these have highlighted a discrepancy between government policy and public concern. With a few exceptions, governments have been keen to encourage the introduction of genetic engineering into the food supply. Opinion polls, however, have shown that most people would rather they did not have to eat it. Concerns fall into a number of categories:
Choice - consumers are worried that lack of segregation and labelling together with the fact that so many foods are being introduced will leave them unable to exercise free choice.
Health - people are becoming aware that there is a scientific basis to safety concerns about GE food, and are reluctant to replace food they know to be safe with food that might not be. A lack of trust in official assurances of safety, which has been exacerbated by the BSE crisis in the UK, has made people very suspicious of claims that there 'is no evidence of harm'.
Ethics - for some people the main issue is not whether genetically engineered food is safe or not, but the fact that it is unnatural and unnecessary. For some it offends deeply held principles about the relationship between humanity and nature.
Politics - International free-trade agreements are increasing the power of commercial interests and people are concerned that governments are being influenced by unelected bodies.
Profit - trade in GE food and crops is dominated by a handful of multinational corporations such as Monsanto, Novartis, Zeneca, Aventis and DuPont. It is widely believed that these are the only beneficiaries of genetically engineered foods.
Environment - there is growing evidence that genetic engineering poses new risks to ecosystems, with the potential to threaten biodiversity, wildlife and truly sustainable forms of agriculture. According to the research, it is the potential for long-term effects that most concerns people. Critics of the technology argue that once GE organisms have been released into the environment they may transfer their characteristics to other organisms and can never be recalled or contained.

7. Labelling
When people began to realise they were eating GE food without their knowledge or consent, there were immediate calls from consumer organisations around the world for mandatory labelling of all GE food.
On the 27th of May 1998, Codex Alimentarius (a UN body responsible for establishing international rules on food policy) rejected these calls in favour of a much more limited labelling regime that suited the food and genetic engineering industries. They used the argument of substantial equivalence to say that it would be discriminatory to enforce mandatory labelling of GE food, and suggested that this would constitute an illegal trade barrier. Mandatory labelling could mean that consumers would be able to boycott GE products, and that segregation would need to be introduced, potentially making GE food uneconomical for the food industry. Independent scientists have pointed out that GE food is in fact 'substantially different' from other food and that labelling is essential in order to be able to trace any health problems that may arise.
New EU legislation on partial labelling of GE soya and maize was introduced from the 1st of September '98. In Europe, GE soya is estimated to be present in about 60% of all processed food in forms such as vegetable oil, soya flour, lecithin and soya protein. GE maize can be found in about 50% of processed foods as corn, cornstarch, cornflour and corn syrup. Over 90% of these ingredients are excluded from the new labelling scheme.
So-called scientific arguments have been used by the food industry as a basis for refusing to label derivatives such as soya oil because most of the DNA is destroyed when food is processed. Surveys have found that even so, most people want the right to know if the food they are eating comes from something that has been genetically engineered, and they may have ethical reasons or concerns about environmental issues that make them want to avoid it.
· The most certain way of avoiding GE food is to eat organic produce. In the spring of '98, the US Department of Agriculture put forward legislation which would have compromised this: they proposed that GE food could be labelled as 'organic'. Eventually these plans were rejected when they received over 280,000 letters of complaint.
· There is evidence that the United States government has been applying pressure on other countries to reject labelling regulations. A New Zealand cabinet document from 19th February '98 showed that the US had threatened to pull out of a potential free-trade agreement with the New Zealand government because of its plans to test and label GE food. The document stated that "The United States have told us that such an approach could impact negatively on the bilateral trade relationship and potentially end any chance of a New Zealand - United States Free Trade Agreement."

8. Who is in control?
The genetic engineering industry is dominated by a handful of multinational corporations holding interests in food, additives, pharmaceuticals, chemicals and seeds. These corporations are beginning to hold monopolies in the global market for genetically engineered products. This is being facilitated through:
1. the World Trade Organisation - which gives priority to free-trade and makes it difficult for countries to refuse a new product or technology even if they have concerns about its potential impact on health or the environment.
2. patenting rights - which allow corporations to patent new genetically engineered varieties. This gives them control over huge areas of the market. It is very expensive to research, develop and patent new crops, and this reinforces the trend towards market dominance by the larger companies.
3. a systematic process of acquisitions and mergers - these mergers incorporate seed companies, genetic engineering companies and other related interests. Monsanto, for example, has spent $8 billion on new acquisitions in the past three years.
"This is not just a consolidation of seed companies, it's really a consolidation of the entire food chain "
Robert T. Fraley, co-president of Monsanto's agricultural sector
Years of intense lobbying by the industry are beginning to pay off. Their share of a global food market now worth $2000 billion a year is increasing rapidly. Some analysts suggest that if current trends continue, the majority of the food we eat could be genetically engineered within a decade. Most of the industrialised nations have now adopted the biotech agenda as their own and are encouraging investment in genetic engineering as a route to profit and competitive advantage. Close relationships between industry and national governments are increasingly becoming causes for concern.
The United States government in particular has been criticised for 'revolving doors' between the White House and the genetic engineering industry. Many of the people now sitting on key regulatory bodies such as the Food and Drug Administration have strong links to these multinational corporations.
In a document leaked to Greenpeace, PR firm Burson Marsteller demonstrated confidence in the proactive stance of national governments. They advised EuropaBio (a consortium of GE companies with interests in Europe) to refrain from partaking in any public debate and leave it to " those charged with public trust, politicians and regulators, to assure the public that biotech products are safe.”

I think it is all too clear that genetic manipulation is far from safe to use. I know that I only gave arguments against it, but still, I think the fact that we know so little about what genes do, shows we shouldn’t offer genetically manipulated food to the consumer market. We don’t know if maybe combinations of certain genes give us another effect in our body, which wouldn’t surprise me seeing how little progress there is in the world of genetic manipulation. I hope I have provided you with information, and thank-you for reading my paper.



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