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Kerala Plus Two Botany Notes Chapter 5 Biotechnology and its Applications
Biotechnological Applications In Agriculture
The important methods that useful for increasing food production are
| (i) Agro-chemical based agriculture (ii) Organic agriculture; and (iii) Genetically engineered crop-based agriculture |
The Green Revolution helped to increase food production in many fold but it is not enough to meet the demand of growing human population. Here Genetically modified crops are the possible solution for this crisis.
GM (Genetically Modified) plants are useful in many ways
- Made crops more tolerant to abiotic stresses (cold, drought, salt, heat).
- Reduced reliance on chemical pesticides (pest-resistant crops).
- Helped to reduce post harvest losses.
- Increased efficiency of mineral usage by plants
- Enhanced nutritional value of food, e.g., Vitamin ‘A’ enriched Golden rice.
Eg-Bt cotton, Bt corn, rice, tomato, potato, and soyabean, etc have a gene for resistance to insects.
Bt Cotton
Bt toxin producing cry genes are isolated from Bacillus thuringiensis and inserted into the several crop plants such as cotton. The isolation of genes depends upon the crop and the targeted pest because most Bt toxins are insect-group specific,
For example
| 1. crylAc and cryllAb control the cotton bollworms 2. crylAb controls corn borer |
Insecticidal protein of some species of Bacillus thuringiensis that kill certain insects such as lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes).
Bt toxin protein exist as inactive protoxins but it is converted into an active form in the presence of the alkaline pH of insect gut. The activated toxin binds to the surface of midgut epithelial cells and create pores that cause cell swelling and lysis and results in the death of insect.
Pest Resistant Plants:
Nematode Meloidegyne incognitia infects the roots of tobacco plants and causes a great reduction in yield. It is nessary to control the attack of insect pest.
The best method used to prevent the attack of nematode is RNA interference (RNAi). It involves silencing of a specific mRNA of nematode.
Here the complementary dsRNA molecule that binds to and prevents translation of the mRNA (silencing).
After the insertion of nematode-specific genes by Agrobacterium vectors into the host plant, it produce both sense and antisense RNA in the host cells. These two RNA’s being complementary to each other formed a double-stranded (dsRNA) that initiated RNAi and silenced the specific mRNA of the nematode.
Biotechnological Applications In Medicine
The recombinant DNA technological processes that helpful in the mass production of safe and more effective therapeutic drugs.
| In world, about 30 recombinant therapeutics are marketed for human-use. In India, 12 of these are presently being marketed. |
1. Genetically Engineered Insulin:
Insulin for diabetes was extracted from pancreas of slaughtered cattle and pigs, it caused allergic disease in some patients. In humans, insulin is synthesised as a prohormone which contains an extra stretch called the C peptide. It is removed and converted into a fully mature and functional insulin.
It consists of two short polypeptide chains: chain A and chain B, that are linked together by disulphide bridges.
| An American company Eli Lilly in 1983 prepared two DNA sequences corresponding to A and B, chains of human insulin, and inserted 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. |
2. Gene Therapy:
It is the replacement of defective gene by functional gene. This is done by transferring the functional gene into the individual cells, tissues or embryo to treat a disease.
The first reported case of gene therapy was adenosine deaminase (ADA) deficiency that seriously affected the functioning of the immune system. It is due to the deficiency of gene for adenosine deaminase.
Before genetic engineering, ADA deficiency cured by bone marrow transplantation or enzyme replacement therapy.
In the first step of gene therapy, lymphocytes from the blood of the patient are cultured and functional ADA cDNA is introduced in it. Then, these cells are return back to the patient. So that the patient requires frequently such genetically engineered lymphocytes.
The permanent cure for such disease is to introduce functional ADA cDNA into cells at early embryonic stages.
3. Molecular Diagnosis:
Early diagnosis of disease is possible by
| 1. Recombinant DNA technology 2. Polymerase Chain Reaction (PCR) and 3. Enzyme Linked Immuno-sorbent Assay (ELISA) |
Low concentration of a bacteria or virus can be detected by amplification of their nucleic acid by PCR. It is used to detect HIV in suspected AIDS patients and detect mutations in suspected cancer patients It is also used to identify genetic disorders.
The presence of mutated gene can be detected by a probe. A single stranded DNA or RNA, tagged with a radioactive molecule. It is then hybridise to its complementary DNA in a clone of cells. By using autoradiography it is observed that the probe not have any complimentarity with the mutated gene.
Transgenic Animals
Out of many transgenic animals such as rats, rabbits, pigs, sheep, cows fish, etc. 95 percent of transgenic animals are mice.
Importance of such animals are
(i) Normal physiology and development:
Transgenic animals can be used to study of how genes are regulated, and how they affect the normal functions of the body and its development, e.g., study of insulin-like growth factor.
(ii) Study of disease:
Transgenic animals can be used to know, how genes contribute to the development of disease. Today transgenic models exist for many human diseases such as cancer, cystic fibrosis, rheumatoid arthritis and Alzheimer’s disease.
(iii) Biological products:
Transgenic animals that produce useful biological products. For example the introduction of genes which codes for a particular product such as human protein (-antitrypsin) used to treat emphysema. Another examples of disease treated are phenylketonuria (PKU) and cystic fibrosis.
In 1997, the first transgenic cow, Rosie, produced human protein-enriched milk (2.4 grams per litre). The milk contained the human alpha-lactalbumin. It is nutritionally a more balanced product for human babies than natural cow-milk.
(iv) Chemical and vaccine safety testing:
Transgenic animals carry genes that sensitive to toxic substances than non-transgenic animals. So they are exposed to the toxic substances and the effects studied.
Ethical Issues
Some ethical standards are maintained to evaluate the morality of all human activities that are either useful or harmful because the genetically modified organisms have unpredictable results.
| Government of India has set up organisations such as GEAC (Genetic Engineering Approval Committee), they take decisions regarding the validity of GM research and the safety of introducing GM-organisms for public services. |
Today the patents are given for products and technologies that make use of the genetic materials, plants, and other biological resources, that have long been identified, developed, and used by farmers and indigenous people of a specific region/country. This is an important problem.
For example, it is estimated that 200,000 varieties of rice grown in India. Of which Basmati rice is distinct for its aroma and flavour. It is significant because this variety was referred in ancient texts, folklore, and poetry.
In 1997, an American company got patent rights on Basmati rice. It was helped the company to sell a ‘new’ variety of Basmati in the US and abroad. It is derived from Indian farmer’s varieties. But the patenting procedure restricts the selling and exporting of Basmati rice by other countries.
Similar attempts have also been made to patent uses, products, and processes based on Indian traditional herbal medicines, e.g., turmeric neem.
Therefore it is necessary to resist these patent applications of other countries/individuals because they permanently take overfull control of our resources.
Biopiracy
| It is the unauthorised use of bio-resources by multinational companies and other organisations without compensatory payment. |
Industrialised nations are financially rich but poor in biodiversity and traditional knowledge But the developing nations is rich in biodiversity and traditional knowledge related to bio-resources.
Here the sharing between developed and developing countries for traditional knowledge related to bio-resources has not been take place on the basis of compensatory payment. Therefore, some nations are developing laws to prevent such unauthorised exploitation of their bio-resources and traditional knowledge.
Recently Indian Parliament cleared the second amendment of the Indian Patents Bill, that takes such issues related to patents.