Biotechnological Applications in Agriculture: The Green Revolution succeeded in tripling the food supply but was not enough to feed the growing human population. To overcome this, Genetically Modified Organisms (GMO) (plants, bacteria, fungi, and animals whose genes have been altered by manipulation) are used. GM plants have been useful to make crops more tolerant to abiotic stresses (cold, drought, salt, heat), reduce reliance on chemical pesticides (pest-resistant crops), help to reduce post-harvest losses, and increase efficiency of mineral usage by plants.

• Bt Cotton: The bacterium Bacillus thuringiensis produces proteins that kill certain insects such as lepidopterans (tobacco budworm, armyworm), coleopterans (beetles), and dipterans (flies, mosquitoes). B. thuringiensis forms protein crystals containing a toxic insecticidal protein. The protein exists as an inactive protoxin but, once ingested by the insect, it is converted into an active form due to the alkaline pH of the gut, which solubilizes the crystals. The activated toxin binds to the surface of midgut epithelial cells and creates pores that cause cell swelling and lysis, eventually causing death.

  The toxin is coded by a gene named cry. There are a number of them, for example, the proteins encoded by the genes cryIAc and cryIIAb control the cotton bollworms, while that of cryIAb controls corn borer.

• Pest Resistant Plants: A nematode Meloidegyne incognita infects the roots of tobacco plants and causes a great reduction in yield. A novel strategy was adopted based on the process of RNA interference (RNAi). RNAi takes place in all eukaryotic organisms as a method of cellular defense. This method involves silencing a specific mRNA due to a complementary dsRNA molecule that binds to and prevents translation of the mRNA (silencing). The source of this complementary RNA could be from an infection by viruses having RNA genomes or mobile genetic elements (transposons) that replicate via an RNA intermediate. Using Agrobacterium vectors, nematode-specific genes were introduced into the host plant. The introduction produced both sense and anti-sense RNA in the host cells, which formed a double-stranded (dsRNA) that initiated RNAi and silenced the specific mRNA of the nematode.

   Biotechnological Applications in Medicine:

• Genetically Engineered Insulin: Management of adult-onset diabetes is possible by taking insulin at regular intervals. Insulin consists of two short polypeptide chains: chain A and chain B, linked together by disulphide bridges. In mammals, including humans, insulin is synthesized as a pro-hormone which contains an extra stretch called the C peptide. This C peptide is not present in the mature insulin and is removed during maturation. The main challenge for production of insulin using rDNA techniques was getting insulin assembled into a mature form. In 1983, Eli Lilly (an American company) prepared two DNA sequences corresponding to A and B, chains of human insulin and introduced them in plasmids of E. coli to produce insulin chains. Chains A and B were produced separately, extracted and combined by creating disulfide bonds to form human insulin.

• Gene Therapy: A collection of methods that allows correction of a gene defect that has been diagnosed in a child/embryo. The first clinical gene therapy was given in 1990 to a 4-year-old girl with Adenosine Deaminase (ADA) deficiency. This enzyme is crucial for the immune system to function (SCID). In some children, ADA deficiency can be cured by bone marrow transplantation or enzyme replacement therapy, but neither is completely curative. In gene therapy, lymphocytes from the blood of the patient are grown in culture outside the body. A functional ADA cDNA (using a retroviral vector) is then introduced into these lymphocytes, which are subsequently returned to the patient. However, as these cells are not immortal, the patient requires periodic infusion of such genetically engineered lymphocytes. If the gene isolated from marrow cells producing ADA is introduced into cells at early embryonic stages, it could be a permanent cure.

• Molecular Diagnosis: Early detection is not possible with conventional methods (serum and urine analysis).

  • PCR (Polymerase Chain Reaction): Can detect very low amounts of DNA. It is now routinely used to detect HIV in suspected AIDS patients and to detect mutations in genes in suspected cancer patients.

     

  • ELISA (Enzyme Linked Immuno-Sorbent Assay): Based on the principle of antigen-antibody interaction. Infection by a pathogen can be detected by the presence of antigens (proteins, glycoproteins, etc.) or by detecting the antibodies synthesized against the pathogen.

  • Probe: A single-stranded DNA or RNA, tagged with a radioactive molecule is allowed to hybridize to its complementary DNA in a clone of cells followed by detection using autoradiography. The clone having the mutated gene will not appear on the photographic film because the probe will not have complementarity with the mutated gene.

     Transgenic Animals: Animals that have had their DNA manipulated to possess and express an extra (foreign) gene. 95%27 of all existing transgenic animals are mice.

1. Normal physiology and development: Study of how genes are regulated (e.g., study of complex factors like Insulin-like growth factor).

    

2. Study of disease: Models for human diseases like cancer, cystic fibrosis, rheumatoid arthritis, and Alzheimer’s.

    

3. Biological products: Transgenic animals can produce biological products. Example: Rosie, the first transgenic cow (1997), produced human protein-enriched milk (2.4 grams per litre). The milk contained the human alpha-lactalbumin and was nutritionally a more balanced product for human babies than natural cow-milk. Transgenic animals are also used to produce alpha-1-antitrypsin used to treat emphysema.

4. Vaccine safety: Transgenic mice are being developed for use in testing the safety of vaccines (e.g., polio vaccine) before they are used on humans.

5. Chemical safety testing: Toxicity testing (more sensitive to toxic substances).

Ethical Issues: The Indian Government has set up organizations such as GEAC (Genetic Engineering Appraisal Committee), which will make decisions regarding the validity of GM research and the safety of introducing GM-organisms for public services.

• Biopiracy: The use of bio-resources by multinational companies and other organizations without proper authorization from the countries and people concerned without compensatory payment.

  • Basmati Rice: There are 27 documented varieties of Basmati grown in India. In 1997, an American company got patent rights on Basmati rice through the US Patent and Trademark Office. This allowed the company to sell a ‘new’ variety of Basmati, in the US and abroad. This ‘new’ variety was actually derived from Indian farmers’ varieties (Indian Basmati was crossed with semi-dwarf varieties).

  • Attempts have also been made to patent uses, products, and processes based on Indian traditional herbal medicines, e.g., Turmeric and Neem.