Genetic Engineering.

« Pseudomonas fluorescens bacterium.

The genetically altered Pseudomonas fluorescens bacterium produces light in proportion to the amount of its activity in breaking down the naphthalene, thus providing a way to monitor the efficiency of the process ( see Bioremediation). A3 Medicine In 1982 the United States Food and Drug Administration (FDA) approved for the first time the medical use of a recombinant DNA protein, the hormone insulin, whichhad been cloned in large quantities by inserting the human insulin gene into the genetic makeup of Escherichia coli bacteria.

Previously, this hormone, used by insulin- dependent people with diabetes mellitus, had been available only in limited quantities from hogs. Since 1982 the FDA has approved other genetically engineered proteins for use in humans, including three cloned in hamster cell cultures: tissue plasminogen activator (tPA), an enzyme used to dissolve blood clots in people who have suffered heart attacks; erythropoetin, a hormone used to stimulate the production of red blood cells in people with severe anemia; and antihemophilic human factor VIII , used by people with hemophilia to prevent and control bleeding or to prepare them for surgery. Another important genetically engineered drug is interferon, a chemical that is produced by the body in tiny amounts.

Engineered interferon is used to fight viraldiseases and as an anticancer drug. Scientists also have employed recombinant DNA to produce medically useful human proteins in animal milk.

In this procedure, the human gene responsible for thedesired protein is first linked to specific genes of the animal that are active only in its mammary (milk-producing) glands.

The egg of the animal is then injected with the linked genes.

The resulting transgenic animals will have these linked genes in every cell of their body but will produce the human protein only in their milk.

The humanprotein is finally extracted from the animal's milk for use as medicine.

In this way, sheep's milk is used to produce alpha-1-antitrypsin, an enzyme used in the treatment of emphysema; cow's milk is used to produce lactoferrin, a protein that combats bacterial infections; and goat's milk is used as yet another way to produce tPA, the blood-clot-dissolving enzyme also cloned in hamster cell cultures. Recombinant DNA also is used in the production of vaccines against disease.

A vaccine contains a portion of an infectious organism that does not cause severe diseasebut does cause the body's immune system to form protective antibodies against the organism.

When a person is vaccinated against a viral disease, the production ofantibodies is actually a reaction to the surface proteins of the coat of the virus.

With recombinant DNA technology, scientists have been able to transfer the genes forsome viral-coat proteins to the cowpox virus, which was used against smallpox in the first efforts at vaccination in the late 18th century.

Vaccination with geneticallyaltered cowpox is now being used against hepatitis, influenza, and herpes simplex viruses.

Genetically engineered cowpox is considered safer than using the disease-causing virus itself and is equally as effective. In humans, recombinant DNA is the basis of gene therapy, in which genes within cells are removed, replaced, or altered to produce new proteins that change thefunction of the cells.

The use of gene therapy has been approved in more than 400 clinical trials for diseases such as cystic fibrosis, emphysema, muscular dystrophy,adenosine deaminase deficiency, and some cancers.

While gene therapy is a promising technique, many problems remain to be solved before gene therapy can reliablycure disease. B Patenting Genetically Engineered Products It takes an average of seven to nine years and an investment of about $55 million to develop, test, and market a new genetically engineered product.

Because of thisgreat cost, companies have sought to patent the results of their discoveries.

In 1980 the Patent and Trademark Office of the U.S.

Department of Commerce issued itsfirst patent on an organism that had been produced with recombinant DNA.

The patent was for an oil-eating bacterium that could be used to clean up oil spills fromships and storage tanks.

Since then, hundreds of patents have been granted for genetically altered bacteria, viruses, and plants.

In 1988 the first patent was issued ona transgenic animal, a strain of laboratory mice whose cells were engineered to contain a cancer-predisposing gene.

The mice are used to test low doses of suspectedcarcinogens, or cancer-causing substances, and to test the effectiveness of anticancer therapies. C Controversies Public reaction to the use of recombinant DNA in genetic engineering has been mixed.

The production of medicines through the use of genetically altered organisms hasgenerally been welcomed.

However, critics of recombinant DNA fear that the pathogenic, or disease-producing, organisms used in some recombinant DNA experiments might develop extremely infectious forms that could cause worldwide epidemics.

In an effort to prevent such an occurrence, the National Institutes of Health (NIH) inthe United States has established regulations restricting the types of recombinant DNA experiments that can be performed using such pathogens.

In Canada,recombinant DNA products are regulated by various government departments, including Agriculture and Agri-Food Canada, Health Canada, Fisheries and OceansCanada, and Environment Canada. Animal rights groups have argued that the production of transgenic animals is harmful to other animals.

Genetically engineered fish raise problems if they interbreedwith other fish that have not been genetically altered.

Some experts fear that this process may change the characteristics of wild fish in unpredictable and possiblyundesirable ways.

A related concern is that engineered fish may compete with wild fish for food and replace wild fish in some areas. The use of genetically engineered bovine somatotropin (BST) to increase the milk yield of dairy cows is particularly controversial.

Some critics question the safety of BSTfor both the cows that are injected with it and the humans who drink the resulting milk.

In the United States, a large percentage of dairy cows are treated with BST, butin Canada, BST cannot legally be sold.

Scientists at Health Canada rejected the legalization of BST in 1999 based on evidence that BST causes health problems for cows.In particular, the Canadian scientists found that BST increases a cow’s likelihood of developing mastitis, or infection of the udder, and it also makes cows moresusceptible to infertility and lameness.

Nevertheless, the scientists consider the milk obtained from cows injected with BST to be safe for human consumption. Transgenic plants also present controversial issues.

Allergens can be transferred from one food crop to another through genetic engineering.

In an attempt to increasethe nutritional value of soybeans, a genetic engineering firm experimentally transferred into soybean plants a Brazil-nut gene that produces a nutritious protein.However, when a study found that the genetically engineered soybeans caused an allergic reaction in people sensitive to Brazil nuts, the project was canceled. Environmentalists fear that the transgenic plants may interbreed with weeds, producing weeds with unwanted characteristics, such as resistance to herbicides.

Anexample of such interbreeding has been demonstrated in experiments involving transgenic oilseed rape.

Environmentalists also argue that, due to natural selection,insects quickly develop resistance to plants that have been engineered to incorporate biological pesticides. Opponents of genetic engineering warn that the use of genetically modified food crops could result in unforeseen problems.

They point to a 1999 study that found thatgenetically modified corn produced pollen that killed monarch butterfly caterpillars in the laboratory.

Although the study results were preliminary, as a precaution theEnvironmental Protection Agency (EPA) established new regulations in January 2000 to reduce potential risks posed by the corn crop.

Among the new rules, the EPA hasasked farmers to plant unmodified corn crops around the edges of genetically engineered corn fields in order to create a buffer that may prevent toxic pollen fromblowing into butterfly habitats. Many European and developing nations have voiced concern about the health and environmental risks associated with imported genetically modified food crops from the. »