Uses of cloned genes in agriculture, medicine and industry

Uses of cloned genes in agriculture, medicine and industry:-

Uses of cloned genes in Agriculture:- 

> Crop plants have been the focus of genetic engineering as efforts are being made to improve the traits of plants. Transgenic plants are developed for the following reasons:

i. Gene insertion may result in improvement in the agricultural or commercial value of a plant.

ii. Transgenic plants can act as a living bioreactors facilitating production of commercially important proteins or metabolites.

iii. Transgenic plant helps in the understanding the function of different genes.

> Desirable Properties in Plants:- A number of genes can be combined with crops to produce desirable properties such as:

i. Herbicide, drought, freeze or disease resistance.

ii. Higher yield; Tolerance towards cold, drought, salt.

iii. Faster growth.

iv. Improved nutrition.

v. Delay of senescence.

vi. Longer shelf life.

vii. Increased post-harvest shelf life.

viii. Altered flower pigmentation.

ix. Nitrogen fixation Capacity to fix atmospheric nitrogen.

Genetically Modified Plant Products:-

i. Increased levels of iron and vitamin A in rice.

ii. Fast ripening process in banana.

iii. Improved feed value in maize.

iv. High levels of flavonols in tomatoes.

v. Drought tolerance in maize.

vi. Increased phosphorus availability in maize.

vii. Plants more tolerant to arsenic.

viii. Edible vaccines from plants.

ix. Low lignin content in trees.

x. “Glowing plant” with gene from firefly that glows in the dark.

Uses of cloned genes in Food Industry:- Genetic engineering finds application in food industry which is a result of modification of the genetic material of plants or animals. Many genetically modified (GM) whole foods or ingredients present in them available today are a result of gene modification. 

> Genetically modified foods are obtained from genetically modified organisms, or transgenic crops.

Genetic engineering has resulted in a number of improved traits in transgenic plants by genetic

alteration. Some of these traits are:

i. Production of extra nutrients in the food.

ii. Increased growth rate.

iii. Disease resistance and herbicide resistance.

iv. Better taste.

v. Increased shelf life etc.

vi. Lesser requirement for water.

> The first genetically modified whole food crop was tomato (called Flavr Savr), which was made more

rot-resistant. This was the first commercial genetically modified food marketed by Calgene as Flavr

Savr delayed-ripening tomato in 1994. Genetic engineering mainly focusses on cash crops as shown in

table.

List of Genetically Modified Foods

Uses of cloned genes in Medicine:- By genetic engineering a variety of medical products are available today. Among these products, insulin and human growth hormone were first commercially available products obtained from recombinant E. coli.

> Recombinant insulin:- It is the result of successful genetic engineering. The initial production of insulin involved the separate synthesis of the insulin A- and B-chains in two bacterial strains. Both the insulin A and B chains genes were placed under the control of the lac promoter for inducible expression by lactose inducer. After purification of the A- and B-chains from the bacteria, the chains were then linked chemically to produce the final insulin. Recombinant-insulin is now commercially available in several forms and is involve in diabetes therapy.

> Pharming:- The production of pharmaceutical products from transgenic animals is considered as “Pharming” ( taken from "farming" and "pharmaceutical”). Pharming involves the use of genetic engineering technique to insert genes into host animals or plants resulting in expression of useful pharmaceuticals products. The development of transgenic "super mice" in 1982 led to the wide application of pharming in pharmaceutical industry. Human drug, TPA (tissue plasminogen activator) a valuable therapeutic protein to treat blood clots was first produced from "Super mice" as a result of genetic alteration in 1987. TPA is a protease that has a role in breaking down blood clots by breaking up fibrin, the protein involved in clot formation. Thus, TPA is used in heart attack victims where it helps to reduce the damage caused by coronary thrombosis. Since then pharming has resulted in a plethora of recombinant products made in E. coli which is shown in table.

> Recombinant vaccines:- These are an important group of therapeutic products. A number of vaccines are now available for animals, and human which is going to have a major impact in the healthcare industry. One of the initial vaccines produced by rDNA method involves the cloning of the surface antigen of the hepatitis B virus (HBsAg) in the yeast S. cerevisiae under the control of the alcohol dehydrogenase promoter. A number of recombinant vaccines are now commercially prepared by the recombinant DNA technology, where only the outside coat protein of the microorganism is expressed in the host to create the vaccine. The expressed protein can then be purified from the recombinant host and used for inoculation. This method has the advantage of safe delivery of antigen without transferring the actual disease-causing microbe to the host. Currently recombinant vaccines for the hepatitis B virus, herpes type 2 viruses, and malaria is under trial for use in future.

> Edible Vaccine:- The latest development involves the production of edible vaccine using transgenic plants as a delivery mechanism, which involves the presence of vaccine in the edible part of the plant. This technology has tremendous potential as it enables easy delivery of vaccine by just consumption of the edible part. The trials for development of a vaccine-containing banana or tomato are currently under way.

> Gene Therapy:- With the advancement of genetic engineering it is now possible to treat the genetic defects by the replacement of the defective gene with a functional copy by gene therapy. This technique has great potential in the treatment of genetic diseases. The gene therapy protocol can be made effective by the following approaches:

- Insertion of a normal gene to compensate for a nonfunctional gene.

- Repair of an abnormal gene by selective reverse mutation.

- Alteration in the regulation of gene pairs.

It involves the following steps:-

i. Delivery of the therapeutic gene by a suitable vector into target cell of the patient.

ii. Infection of the target cells with the viral vector.

iii. Insertion of the genetic material into the target cell by recombination between the defective gene and the functional copy of the gene.

iv Expression of functional proteins from the inserted gene resulting in a normal cell.

Treatment of genetic disorder by gene therapy:- A number of genetic disorder caused by single-gene defects, such as cystic fibrosis, muscular dystrophy, hemophilia, sickle cell anaemia and AIDS can be treated by gene therapy approach for which the clinical trial is underway. However, there are some problems associated to a successful gene therapy. These are:

i. Introduction of large segment of DNA to the right site on the genome becomes problematic.

ii. Sometimes the defensive mechanism of the host destroys the genetically altered cells.

Ethical consideration of genetic engineering:- The characteristics of genetic engineering possess vast promise but also involve some potential threat to mankind bringing challenges to our ethical system and religious beliefs. The main reason genetically modified organisms are not more widely used is due to ethical concerns which are:

i. GMO foods are not independently tested before the food is approved so the health of the humans is threatened because the consumption of it could cause allergic reaction.

ii. Another safety consideration is the health of farmers and their families, animals and communities who are put at risk with exposure to chemicals used in tandem with GMO seeds.

iii. The genetically engineered organisms which are released into the environment can be a threat to it because they can interact with other living organisms in the environment in an unpredictable manner.

iv. Genetic engineering can result in creation of toxic-vegetation, posing serious threat to wild life and may result in new strains of molds and fungi.

v. Genetic engineering could be used to create biological weapons.

vi. The creation of pathogen resistance in plant may result in development of strong resistant variety of pathogens.

vii. There is serious concern that animals will suffer as a result of being genetically modified as use of growth hormones may cause limb deformation and arthritis as animals grow.

viii. Genetic engineering applied to human may have serious implications like parents opting for designer baby i.e. deciding their children's eye colors, heights or even genders before birth. Another concern is that if tests are carried out for genetic diseases on unborn babies – could lead to abortion if a disease is shown to be present.