Biotechnology has a wide range application such
as biopharmaceuticals, therapeutics, diagnostics, genetically modified crops
for agriculture, processed food, bioremediation, waste treatment and energy
production.
a. Providing the best catalyst in the form of
improved organism usually a microbe or pure enzyme.
b. Creating optimal conditions through
engineering for a catalyst to act.
c. Downstream processing technologies to
purify the protein/organic compound.
APPLICATIONS
IN AGRICULTURE
Three options for increasing food
production
a. Agro-chemical based agriculture
b. Organic agriculture
c.
Genetically engineered crop-based agriculture
Genetically Modified
Organisms (GMO) or transgenic organisms are the plants,
bacteria, fungi & animals whose genes are altered by manipulation.
Advantages of genetic modification in
plants:
· It makes crops more tolerant to abiotic
stresses (cold, drought, salt, heat etc).
· Pest-resistant crops reduce the use of
chemical pesticides.
· It helps to reduce post harvest losses.
· It increases efficiency of mineral usage by
plants (this prevents early exhaustion of fertility of soil).
· It enhances nutritional value of food. E.g.
Vitamin ‘A’ enriched rice.
· GM is used to create tailor-made plants to
supply alternative resources to industries, in the form of starches, fuels and
pharmaceuticals.
Pest
Resistant Plants
- Pest Resistant Plants act as bio-pesticide.
- It reduces the need for insecticides.
-
E.g. Bt cotton, Bt corn, rice, tomato, potato, soyabean etc.
Bt Cotton:
-
Some strains of Bacillus thuringiensis have proteins that kill insects like coleopterans (beetles) lepidopterans
(tobacco budworm, armyworm) & dipterans (flies, mosquitoes).
-
B.
thuringiensis forms a toxic insecticidal protein (Bt
toxin) crystal during a particular phase of their
growth. It does not kill the Bacillus as it exists as inactive protoxins.
-
When
an insect ingest the inactive toxin, it is
converted into active toxin due to the alkaline pH of the gut which solubilise
the crystals. The toxin binds to the surface of midgut epithelial cells and
creates pores. It causes cell swelling and lysis and death of the insect.
- Bt toxin genes were isolated from B. thuringiensis and
incorporated into crop plants such as cotton.
- Most Bt toxins are insect-group specific.
The toxin is coded by a gene named cry. E.g. the proteins encoded by the genes cryIAc and cryIIAb control
the cotton bollworms that of cryIAb
controls corn borer.
Nematode
resistance in tobacco plants:
- A nematode Meloidegyne incognitia infects
the roots of tobacco plants and causes a great reduction in yield.
- RNA interference (RNAi) strategy is used to prevent this infestation.
- RNAi is a method of cellular defense in all
eukaryotic organisms. It prevents translation of a specific mRNA (silencing)
due to a complementary dsRNA molecule.
- The source of this complementary RNA is
from an infection by RNA viruses or mobile genetic elements (transposons) that
replicate via an RNA intermediate.
- Using Agrobacterium
vectors, nematode-specific genes (DNA) were
introduced into the host plant. It produced both sense & anti-sense RNA in
host cells. These two RNA’s being complementary to each other formed a double
stranded (dsRNA) that initiated RNAi and thus, silenced the specific mRNA of
nematode. Thus the parasite cannot survive in a transgenic host expressing
specific interfering RNA.
APPLICATIONS
IN MEDICINE
- The recombinant DNA technology helps for
the mass production of safe and more effective therapeutic drugs.
- The recombinant therapeutics does not
induce unwanted immunological responses as is common in case of similar
products isolated from non-human sources.
- At present, about 30 recombinant
therapeutics have been approved for human-use. In India, 12 of these are
presently being marketed.
Genetically Engineered Insulin:
- Management of adult-onset diabetes is
possible by taking insulin at regular time intervals.
-
Now, it is possible to produce human insulin using
bacteria.
-
Insulin from the pancreas of animals (cattle & pigs)
causes allergy or other types of reactions to the foreign protein.
- Insulin consists of two short polypeptide
chains (chain A & chain B) that are linked together by disulphide bridges.
- In mammals, insulin is synthesized as a
pro-hormone. The pro-hormone needs processing before it becomes a fully mature
and functional hormone.
- The pro-hormone contains an extra stretch
called the C peptide.
This is removed during maturation into insulin.
- In 1983, Eli Lilly an American company
prepared two DNA sequences corresponding to A & B chains of human insulin
and introduced them in plasmids of E.
coli to produce insulin chains. Chains A & B
were produced separately, extracted and combined by creating disulfide bonds to
form human insulin.
Gene
Therapy:
- It is a method to correct a gene defect
diagnosed in a child/embryo. Here, genes are inserted into a person’s cells and
tissues to treat a hereditary disease. It compensates for the non-functional
gene.
- First clinical gene therapy was given in
1990 to a 4-year old girl with adenosine deaminase (ADA) deficiency. The
disorder is caused due to the deletion of the gene for adenosine
deaminase (the enzyme crucial for the immune system to function).
- This can be cured by bone marrow
transplantation or by enzyme replacement therapy (injection of functional ADA).
But these approaches are not completely curative.
- In gene therapy, lymphocytes from the patient’s
blood are grown in a culture. Then, a functional ADA cDNA (using a retroviral
vector) is introduced into these lymphocytes. Then, they are returned to the
patient. This should be periodically repeated as these cells are not immortal.
However, if the ADA gene (from marrow cells) is introduced into cells at early
embryonic stages, it could be a permanent cure.
Molecular
Diagnosis
- Recombinant DNA technology, PCR and Enzyme
Linked Immuno-sorbent Assay (ELISA) are some techniques for early diagnosis.
-
Presence of a pathogen is normally suspected only when the
pathogen has produced a symptom. By this time the concentration of pathogen is
already very high in the body. However, very low concentration of a bacteria or
virus can be detected by amplification of their nucleic acid by PCR.
- PCR is used to detect HIV in suspected AIDS
patients. It is also used to detect mutations in genes in suspected cancer
patients. It is a powerful technique to identify many other genetic disorders.
- A single stranded DNA or RNA, tagged with a
radioactive molecule (probe) is allowed to hybridise to its complementary DNA
in a clone of cells followed by detection using autoradiography. The clone
having the mutated gene will hence not appear on the photographic film, because
the probe will not have complimentarity with the mutated gene.
- ELISA is based on the principle of
antigen-antibody interaction. Infection by pathogen can be detected by the
presence of antigens (proteins, glycoproteins, etc.) or by detecting the
antibodies synthesized against the pathogen.
TRANSGENIC ANIMALS
- These are the animals whose genome has been
altered by introduction of an extra (foreign) gene by manipulation.
- E.g. Transgenic rats, rabbits, pigs, sheep,
cows and fish.
- Over 95% of all existing transgenic animals
are mice.
Benefits
of transgenic animals
· To study normal physiology &
development: Transgenic animals are used to study how
genes are regulated, and how they affect the normal body functions and its
development.
E.g. study of complex factors such as
insulin-like growth factor. Genes (from other species) that alter the formation
of this factor are introduced and the biological effects are studied. This
gives information about the biological role of the factor in the body.
·
To
Study the contribution of genes in the development of a disease: Transgenic models help for investigation
of new treatments for human diseases. E.g. transgenic models for many human
diseases such as cancer, cystic fibrosis, rheumatoid arthritis and Alzheimer’s.
· Biological products: Some medicines contain
biological products, but they are often expensive. Transgenic animals are used
to produce useful biological products by introducing genes which codes for a
particular product.
E.g. human protein (a-1-antitrypsin) used to treat emphysema, products for treatment
of phenylketonuria (PKU) and cystic fibrosis etc.
In 1997, Rosie (first transgenic cow) produced
human protein-enriched milk (2.4 gm per litre). It contains the human a-lactalbumin and is nutritionally more balanced product for
human babies than natural cow-milk.
· Vaccine safety testing: Transgenic mice are used to test the safety of the polio
vaccine. If it is found to be reliable, they can replace the use of monkeys to
test the safety of batches of the vaccine.
· Chemical safety testing (toxicity testing):
Transgenic animals are made that carry
genes which make them more sensitive to toxic substances than non-transgenic
animals. They are exposed to the toxic substances and the effects studied. It
gives immediate results.
ETHICAL ISSUES
· Problem of unpredictable results: Genetic modification may cause unpredictable results when such
organisms are introduced into the ecosystem.
Therefore, Indian Government has set up
organizations like GEAC (Genetic
Engineering Approval Committee), which make decisions about the validity of GM
research and the safety of GM-organisms for public services.
· Problems of patent: Certain companies have got patents for products and technologies
that make use of the genetic materials, plants etc that have been identified,
developed and used by farmers and indigenous people of a specific country. E.g.
Basmati rice, herbal medicines like turmeric, neem etc.
Basmati rice has unique aroma & flavour. India has 27 varieties of Basmati. 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. This had actually
been derived from Indian farmer’s varieties. Indian Basmati was crossed with
semi-dwarf varieties and claimed as a novelty. Other people selling Basmati
rice could be restricted by the patent.
· Biopiracy: It
is the use of bio-resources by
multinational companies and other organizations without proper authorization
from the countries and people concerned.
Most of the industrialized nations are poor
in biodiversity and traditional knowledge. The developing and the
underdeveloped world have rich biodiversity and traditional knowledge related
to bio-resources.
It has to develop laws to prevent
unauthorized exploitation of bio-resources and traditional knowledge.
Indian Parliament has cleared the second
amendment of the Indian Patents Bill that takes such issues into
consideration, including patent terms emergency provisions and research and
development initiative.