Why do we Genetically Engineer Foods?

• Biotechnology is needed to feed the growing population of the world, especially the Third World.

• Reduced chemical inputs, which will be good for the environment.

• Genetic Engineering creates better yields in foods by giving them:– Pest resistance– Herbicide tolerance– Disease resistance– Cold/drought tolerance– More nutrition– Ability to replenish the soil they were grown in.

Engineered food-process

• 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 found in bacteria. The bacteria reproduce rapidly and within a short time thousands of identical copies can be made of the ‘new’ gene.

• There are now two principal methods that can be used to force the ‘new’ gene into the DNA of the plant that is to be engineered. 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.

• Or, 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 animals and fish are produced by microinjection. Fertilized eggs are injected with new genes which will, in some cases, enter the chromosomes and be incorporated into the animal’s own DNA.

• Techniques used to transfer genes have a low success rate, so 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.

Genetically Engineered Foods: Fears

"Human health effects can include higher risks of toxicity, allergenicity, antibiotic resistance, immune-suppression and cancer. As for environmental impacts, the use of genetic engineering in agriculture could lead to uncontrolled biological pollution, threatening numerous microbial, plant and animal species with extinction, and the potential contamination of non-genetically engineered life forms with novel and possibly hazardous genetic material." (http://www.centerforfoodsafety.org/geneticall7.cfm)

Other Possible ProblemsUnintended harm to other organismsReduced effectiveness of pesticidesGene transfer to non-target speciesAllergiesUnknown effects

Experiment on rats of the same age. Control group on the left. Rat on the right was fed “GM-soy.”

• Pusztai reportedly fed rats potatoes genetically modified to have snowdrop lectin (which is an insecticide). The rats had stunted growth + immune system damage

• Controversy: confusion over the lectin was from snowdrop (cool) or jackbean (poisonous).

• research republished in October 1999, reviewed by 6 reviewers. “The paper did not mention stunted growth or immunity issues, but reported that rats fed on potatoes genetically modified with the snowdrop lectin had "thickening in the mucosal lining of their colon and their jejunum" when compared with rats fed non-modified potatoes.”

• While the implications of this study are alarming, the study had a number of holes and its results cannot be taken as a reflection on Genetic Engineering.

Case Study – Pusztai Potato Data

Safety

• GM foods are highly regulated and they must pass extensive safety testing before reaching market.

• GM foods have been consumed by hundreds of millions of people so far with no reported health problems to date.

• Still, it is possible that genetic engineering can unintentionally transfer allergens between foods. Also Genetic Engineering can create new allergens.

• Genetic Engineering has only been around for 15 years. There are worries that long-term problems involving GM foods could be in our future.

Medical uses of Genetic Engineering• Pigs are often chosen as transgenic animals because their

physiology and organ size are so similar to humans. The hope is that pig organs can be used for organ transplantation, known as xenotransplantation.– This will alleviate the shortage of human hearts and

kidneys, which are in scarce supply.• Researchers are also exploring the use of cell transplantation

therapy for patients with spinal cord injury or Parkinson’s disease. There are several drawbacks to xenotransplantation.

Medical uses of Genetic Engineering (2)

• Additionally, commercial companies seek to derive therapeutic proteins, such as monoclonal antibodies, from the milk of transgenic cows, goats, rabbits, and mice and use them to administer drugs in treatment of rheumatoid arthritis, cancer, and other autoimmune disorders.

• Other uses of this transgenic combination include growing tissue on a scaffolding, or supporting framework. This then can be used as a temporary skin substitute for healing wounds or burns or as replacement cartilage, heart valves, cerebrospinal shunts, or even collagen tubes to guide re-growth of nerves that have been injured.

Medical uses of Genetic Engineering (3)• Scientists harvest stem cells that can be used to

study human development and to treat disease. • Stem cells are important to biomedical

researchers because they can be used to generate virtually any type of specialized cell in the human body.

• The extraction process destroys the embryo, which raises a variety of ethical concerns.

• Stem cells are so versatile that they can be modified into cardiac tissue, spinal tissue, and possibly nerve tissue.

• Stem cells may be the key to curing diseases caused by the erosions of nerves such as Alzheimers and ALS.

Ethical problems• If the blending of nonhuman animal and human

DNA results, intentionally or not, in trans-species entities possessing degrees of intelligence or sentience never before seen in nonhuman animals, should these entities be given rights and special protections?

• It is possible that in blending DNA of different species we might be making our subjects susceptible to new forms of disease?

• Could we inadvertently create a super-disease?• Is it right for parents to genetically alter their

children before birth?