Introduction
Biotechnology deals with industrial scale production of biopharmaceuticals
and biologicals using genetically modified microbes, fungi, plants and animals.
The applications of biotechnology include therapeutics,
diagnostics, genetically modified crops for agriculture,
processed food, bioremediation, waste treatment, and energy production.
Three critical research areas of biotechnology are:
(i) Providing the best catalyst in the form of improved
organism usually a microbe or pure enzyme
(ii) Creating optimal conditions through engineering for a catalyst to act, and
(iii) Downstream processing technologies to purify the protein/organic compound.
BIOTECHNOLOGICAL APPLICATIONS IN AGRICULTURE
(i) Agro-chemical based agriculture;
ii) organic agriculture; and
(iii) genetically engineered crop-based agriculture.
The Green Revolution somehow succeeded in tripling the food supply but yet
it was not enough to feed the growing human population.
Increased yields have partly been due to the use of improved crop varieties, but mainly
due to the use of better management practices and use of agrochemicals (fertilisers and pesticides).
For farmers in the developing world,
agrochemicals are often too expensive, and further increases in yield with
existing varieties are not possible using conventional breeding.
Plants, bacteria, fungi and animals whose genes have been altered by
manipulation are called Genetically Modified Organisms (GMO).
GM plants are useful in many ways.
Genetic modification:
(i) made crops more tolerant to abiotic stresses (cold, drought, salt, heat).
(ii) reduced reliance on chemical pesticides (pest-resistant crops).
(iii) helped to reduce post harvest losses.
(iv) increased efficiency of mineral usage by plants (this prevents early exhaustion of fertility of soil).
(v) enhanced nutritional value of food, e.g., Vitamin ‘A’ enriched rice.
The production of pest resistant plants can decrease the amount of pesticide used.
Bt toxin is produced by a bacterium called Bacillus thuringiensis (Bt for short).
Examples are Bt cotton, Bt corn, rice, tomato, potato and soyabean etc.
Bt Cotton :
Some strains of Bacillus thuringiensis produce proteins that
kill certain insects such as lepidopterans (tobacco budworm, armyworm),
coleopterans (beetles) and dipterans (flies, mosquitoes).
The Bt toxin protein exist as inactive protoxins but
once an insect ingest the inactive toxin, it is converted into an active form of toxin
due to the alkaline pH of the gut which solubilise the crystals.
The activated toxin binds to the surface of midgut epithelial cells and create pores that cause cell swelling and lysis
and eventually cause death of the insect.
The choice of genes depends upon the crop and the targeted pest, as most Bt toxins are insect-group specific.
Pest Resistant Plants :
A nematode Meloidegyne incognitia infects the roots of tobacco plants and causes a great reduction in yield.
A novel strategy was adopted to prevent this infestation which was based on the process of RNA interference (RNAi).
RNAi takes place in all eukaryotic organisms by cellular defense.
This method involves silencing of 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.
The introduction of DNA was such that it produced both sense and anti-sense RNA in the 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 the nematode.
The consequence was that the parasite could not survive in a transgenic host expressing specific interfering RNA.
The transgenic plant hence got protected from the parasite.
BIOTECHNOLOGICAL APPLICATIONS IN MEDICINE
The recombinant DNA technological processes have made great impact
in the area of healthcare by enabling mass production of safe and more effective therapeutic drugs.
Further, the recombinant therapeutics do not induce unwanted immunological responses
as is common in case of similar products isolated from non-human sources.
About 30 recombinant therapeutics have been approved for human-use the world over.
Genetically Engineered Insulin
Earlier insulin used for diabetes was extracted from pancreas of slaughtered cattle and pigs.
Insulin from an animal source, though caused some patients to develop allergy
or other types of reactions to the foreign protein.
Insulin consists of two short polypeptide chains: chain A and chain B,
that are linked together by disulphide bridges as shown in figure below.
In mammals, including humans, insulin is synthesised as a pro-hormone (like a pro-enzyme,
the pro-hormone also needs to be processed before it becomes a fully mature and functional hormone
which contains an extra stretch called the C peptide.
The C peptide is not present in the mature insulin
and is removed during maturation into insulin.
Gene Therapy
Gene therapy is a collection of methods that allows correction of a
gene defect that has been diagnosed in a child/embryo.
Here genes are inserted into a person’s cells and tissues to treat a disease.
Correction of a genetic defect involves delivery of a normal gene into
the individual or embryo to take over the function of and compensate for the non-functional gene.
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.
The disorder is caused due to the deletion of the gene for adenosine deaminase.
In some children ADA deficiency can be cured by bone marrow transplantation;
in others it can be treated by enzyme replacement therapy, in which functional ADA is given to the patient by injection.
But these approaches are not completely curative.
As a first step towards gene therapy,
lymphocytes from the blood of the patient are grown in a 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.
Because these cells are not immortal, the patient requires
periodic infusion of such genetically engineered lymphocytes.
However, if the gene isolate from marrow cells producing ADA is introduced into cells
at early embryonic stages, it can be a permanent cure.
Molecular Diagnosis
Recombinant DNA technology, Polymerase Chain Reaction (PCR)
and Enzyme Linked Immuno-sorbent Assay (ELISA) are some of the techniques that are used for the purpose of early diagnosis.
Presence of a pathogen (bacteria, viruses, etc.) is normally suspected
only when the pathogen has produced a disease symptom.
During this time,
the concentration of pathogen is already very high in the body.
However,
very low concentration of a bacteria or virus (at a time when the symptoms of the disease are not yet visible)
can be detected by amplification of their nucleic acid by PCR.
PCR is now routinely used to detect HIV in suspected AIDS patients.
It is being used to detect mutations in genes in suspected cancer patients too.
It is a powerful techqnique 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 not appear on the photographic film,
because the probe will not have complementarity 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 synthesised against the pathogen.
TRANSGENIC ANIMALS
Animals that have had their DNA manipulated to possess
and express an extra (foreign) gene are known as transgenic animals.
Transgenic rats, rabbits, pigs, sheep, cows and fish have been produced,
although over 95 per cent of all existing transgenic animals are mice.
Some of the common reasons for producing these animals are mentioned below:
(i) Normal physiology and development:
Transgenic animals can be specifically designed to allow the study of how genes are
regulated, and how they affect the normal functions of the body and its development,
e.g., study of complex factors involved in growth such as insulin-like growth factor.
By introducing genes from other species that alter the formation of this factor
and studying the biological effects that result, information is obtained about the biological role of the factor in the body.
(ii) Study of disease:
Many transgenic animals are designed to increase our understanding of how genes contribute to the development of disease.
These are specially made to serve as models for human diseases so that investigation of new treatments for diseases is made possible.
Today transgenic models exist for many human diseases such as cancer, cystic fibrosis, rheumatoid arthritis and Alzheimer’s.
(iii) Biological products:
Medicines required to treat certain human diseases can contain biological products,
but such products are often expensive to make.
Transgenic animals that produce useful biological products can be created by the introduction of the portion of DNA (or genes)
which codes for a particular product such as human protein (α-1-antitrypsin) used to treat emphysema.
In 1997, the first transgenic cow, Rosie, 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.
(iv) Vaccine safety:
Transgenic mice are being developed for use in
testing the safety of vaccines before they are used on humans.
Transgenic mice are being used to test the safety of the polio vaccine.
If successful and found to be reliable, they could replace the use of
monkeys to test the safety of batches of the vaccine.
(v) Chemical safety testing:
This is known as toxicity/safety testing.
The procedure is the same as that used for testing toxicity of drugs.
Transgenic animals are made that carry genes which make them more
sensitive to toxic substances than non-transgenic animals.
They are then exposed to the toxic substances and the effects studied.
ETHICAL ISSUES
The manipulation of living organisms by the human race cannot go on any further, without regulation.
Some ethical standards are required to evaluate the morality of all human activities
that might help or harm living organisms.
Genetic modification of organisms can have unpredicatable results
when such organisms are introduced into the ecosystem.
Therefore, the Indian Government has set up organisations such as GEAC (Genetic Engineering Approval Committee),
which will make decisions regarding the validity of GM research
and the safety of introducing GM-organisms for public services.
Please find out the regulatory agency for controlling GM-organisms and taking decisions regarding the same and comment your answer.
Biopiracy
is the term used to refer to the use of bio-resources by multinational companies and other organisations without proper
authorisation from the countries and people concerned without compensatory payment.
Most of the industrialised nations are rich financially but poor in biodiversity and traditional knowledge.
In contrast the developing and the underdeveloped world is rich in biodiversity and traditional knowledge related to bio-resources.
Traditional knowledge related to bio-resources can be exploited to develop modern applications
and can also be used to save time, effort and expenditure during their commercialisation.
0 Comments