Genetic engineering today is no longer a new term for the world. Every day in the newspapers, televisions, magazines the new inventions of genetic engineering are noticed. Genetic engineering may be described as the practice that manipulates organism’s genes in order to produce a desired outcome. Other techniques that fall under this category are: recombinant DNA technology, genetic modification (GM) and gene splicing.
The roots of genetic engineering are connected to the ancient times. The Bible also throws some light on genetic engineering where selective breeding has been mentioned. Modern genetic engineering began in 1973 when Herbert Boyer and Stanley Cohen used enzymes to cut a bacteria plasmid and inserted another strand of DNA in the gap created. Both bits of DNA were taken from the same type of bacteria. This step became the milestone in the history of genetic engineering. Recently in 1990, a young child with an extremely poor immune system received genetic therapy in which some of her white blood cells were genetically manipulated and re-introduced into her bloodstream so that her immune system may work properly.
Genetic engineers hope that with enough knowledge and experimentation, it will be possible in the future to create “made-to-order” organisms. This will lead to new innovations, possibly including custom bacteria to clean up chemical spills, or fruit trees that bear different kinds of fruit in different seasons. In this way new type of organisms as well as plants can be developed.
Genetic engineering requires three elements: the gene to be transferred, a host cell into which the gene is inserted, and a vector to bring about the transfer. First of all, the necessary genes to be manipulated have to be ‘isolated’ from the main DNA helix. Then, the genes are ‘inserted’ into a transfer medium such as the plasmid. Third, the transfer medium (i.e., plasmid) is inserted into the organism intended to be modified. Next step is the element transformation whereby several different methods including DNA guns, bacterial transformation, and viral insertion can be used to apply the transfer medium to the new organism. Finally, a stage of separation occurs, where the genetically modified organism (GMO) is isolated from other organisms which have not been successfully modified.
Genetic engineering has affected every field of life whether it is agriculture, food and processing industry, other commercial industries etc. we will discuss them one by one.
1. Agriculture Applications
With the help of genetic engineering it would be possible to prepare clones of genetically manipulated plants and animals of agricultural importance having desirable characteristics. This would increase the nutritive value of plant and animal food. Genetic engineering could lead to the development of plants that would fix nitrogen directly from the atmosphere, rather than from fertilizers which are expensive. Creation of nitrogen fixing bacteria which can live in the roots of crop plants would make fertilization of fields unnecessary. Production of such self fertilizing food crops could bring about a new green revolution. Genetic engineering could create microorganisms which could be used for biological control of harmful pathogens, insect pests, etc.
2. Environmental Applications
Genetically modified microorganisms could be used for degradation of wastes, in sewage, oil spills, etc. Scientists of the General Electric Laboratories of New York have added plasmids to create strains of Pseudomonas that can break down a variety of hydrocarbons and is now used to clear oil spills. It can degrade 60% of the crude oil, while the four parents from which it was derived break down only a few compounds.
3. Industrial Applications
The industrial applications of recombinant DNA technology include the synthesis of substances of commercial importance in industry and pharmacy, improvement of existing fermentation processes, and the production of proteins from wastes.
4. Medicinal Applications
Among the medical applications of genetic engineering are the production of hormones, vaccines, interferon; enzymes, antibodies, antibiotics and vitamins, and in gene therapy for some hereditary diseases.
The hormone insulin is currently produced commercially by extraction from the pancreas of cows and pigs. About 5% of the patients, however, suffer from allergic reactions to animal-produced insulin because of its slight difference in structure from human insulin. Human insulin genes have been implanted in bacteria which, therefore, become capable of synthesizing insulin. Bacterial insulin is identical to human insulin, since it is coded by human genes.
Injecting an animal with an inactivated virus stimulates it into making antibodies against viral proteins. These antibodies protect the animal against infection by the same virus by binding to the virus. Phagocytic cells then remove the virus. Vaccines are manufactured by growing the disease-producing organism in large amounts. This process is often dangerous or impossible. Moreover, there are difficulties in making the vaccine harmless.
Interferons are virus induced proteins produced by cells infected with viruses. They appear to be the body’s first line of defence against viruses. The interferon response is much quicker than the antibody response. Interferons are anti-viral in action. One type of interferon can act. Against many different viruses, i.e. it is not virus specific. It is, however, species specific. Interferon from one organism does not give protection against viruses to cells of another organism. Interferon provides natural defence against such viral diseases as hepatitis and influenza. It also appears to be effective against certain types of cancer, especially cancer of the breast and lymph nodes. Natural interferon is collected from human blood cells and other tissues. It is produced in very small quantities.
The enzyme urokinase, which is used to dissolve blood clots, has been produced by genetically engineered microorganisms.
One of the aims of genetic engineering is the production of hybridomas. These are long lived cells that can produce antibodies for use against disease.
5. Gene therapy for treating hereditary diseases
The earlier gene transplantation experiments were concerned with trans¬planting genes in vitro into isolated cells or into bacteria. Gene transplantation experiments have now been extended to living animals.
6. In Understanding of Biological Processes
Genetic engineering techniques have been used for acquiring basic knowledge about – biological processes like gene structure and expression, chromosome mapping, cell differentiation and the integration of viral genomes. This could lead to a better under¬standing of the genetics of plants and animals, and ultimately of humans.
7. Human Applications
One of the most exciting potential applications of genetic engineering involves the treatment of genetic disorders. Medical scientists now know of about 3,000 disorders that arise because of errors in an individual’s DNA. Conditions such as sickle-cell anemia, Tay-Sachs disease, Duchenne muscular dystrophy, Huntington’s chorea, cystic fibrosis, and Lesch-Nyhan syndrome are the result of the loss, mistaken insertion, or change of a single nitrogen base in a DNA molecule. Genetic engineering makes it possible for scientists to provide individuals who lack a certain gene with correct copies of that gene. The proposal for human cloning are still waiting to come on floor. Genetic engineering has benefited the couples who are infertile.
Safe guards of genetic engineering
The general safeguards for recombinant DNA research are outlined below:
1. Genes coding for the synthesis of toxins or antibiotics should not be introduced into bacteria without proper precautions
2. Genes of animals, animal viruses or tumour viruses should also not be introduced into bacteria without proper precautions.
3. Laboratory facilities should be equipped to reduce the’ possibility’ of escape of pathogenic microorganism by using microbial safety cabinets, hoods, negative pressure laboratories, special traps on drains lines and vacuum lines.
4. Use of microorganisms occupying special ecological niches such as hot springs and salt water should be encourage If such organisms escape they will not be able to survive.
5. Use of non-conjugative plasmids as plasmid cloning vectors is recommended as such plasmids are unable, to, promote their own transfer by conjugation.
Dangers of genetic engineering
Recombinant DNA research involves potential dangers. Genetic engineering could create dangerous new forms of life, either accidentally or deliberately. A host microorganism may acquire harmful characteristics as a result of insertion of foreign genes. If disease-carrying microorganisms formed as a result of genetic manipulation escaped from laboratories, they could cause a variety of diseases. For example, Streptococcus, a bacterium causing rheumatic fever, scarlet fever, strep throat and kidney disease, never acquired penicillin resistance in nature. If a plasmid carrying a gene for penicillin resistance is introduced into Streptococcus it would confer penicillin resistance on the bacterium. Penicillin would now become ineffective against the resistant organism.