BIOTECHNOLOGY AND ITS APPLICATIONS

BIOTECHNOLOGY AND ITS APPLICATIONS

 

The critical areas of biotechnology are:

·         Providing the best catalyst in the form of improved organism usually a microbe or pure enzyme.

·         Creating optimal condition through engineering for a catalyst to act.

·         Downstream processing technologies to purify the protein/organic compound.

BIOTECHNOLOGICAL APPLICATIONS IN AGRICULTURE:

·         Plants, bacteria, fungi and animals whose genes have been altered by manipulation are called Genetically Modified Organisms (GMO).

 

·         Advantages of Genetic Modification in plants.

o    Made crops more tolerant to abiotic stresses (cold, drought, salt, heat)

o    Reduce reliance on chemical pesticides (pest resistant crop)

o    Helped to reduce post harvest losses.

o    Increased efficiency of mineral usage by plants.

o    Enhanced nutritional values of food e.g. vitamin A enriched rice.

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).

·         B.thuringiensis forms protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein.

·         These proteins are present in inactive protoxin form, but become active toxin in 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 eventually cause death of insect

·         Specific Bt toxin genes were isolated form B. thuringiensis and genetically transferred to several plants such as cotton.

·         Crystal proteins are produced by a gene called cry in B. thuringiensis.

·         The protein coded by genes cryIAc and cryIIAb control the cotton bollworms.

·         The protein coded by gene cryIAb controls corn borer.

Pest resistant plants:

·         Several nematodes parasitize a wide variety of plants and animals including human beings.

·         A nematode Meloidegyne incognitia infects the root of tobacco plants and causes a great reduction in yield.

·         Strategy based on RNA interference (RNAi) prevents this infestation.

·         Process by which double-stranded RNA (dsRNA) directs sequence-specific degradation of mRNA

Steps of RNA interference:

·         Double stranded RNA is produced endogenously or exogenously.

·         Using Agrobacterium vectors nematode specific genes were introduced into the host plant (tobacco plant).

·         Introduction of DNA produces both sense and antisense RNA in the host.

·          These two RNA’s being complementary to each other formed a double stranded (dsRNA) that initiated RNAi.

·         The dsRNA injected into the host plant from outside called exogenous dsRNA.

·         The dsRNAs are cleaved into 21-23 nt segments (“small interfering RNAs”, or siRNAs) by an enzyme called Dicer.

·         siRNAs are incorporated into RNA-induced silencing complex (RISC) 

·         Guided by base complementarity of the siRNA, the RISC targets mRNA for degradation.

·         The consequence was that the parasite could not survive in a transgenic host.

BIOTECHNOLOGICAL APPLICATIONS IN MEDICINE:

·         Biotechnology enables mass production of safe and more effective therapeutic drugs.

·         Recombinant therapeutics does not induce unwanted immunological responses as is common in case of similar products isolated from non-human sources.

·         At present around 30 recombinant therapeutics, approved for human-use.

Genetically Engineered Insulin:

·         Taking insulin at regular interval of time is required for adult-onset diabetes.

·         Previously the source of insulin was the slaughtered cattle and pigs.

·         This insulin caused allergy in some patients.

·         Each insulin made of two short polypeptide chains; chain A and chain B that are linked together by disulphide linkage.

·         Insulin synthesized in pancreas as pro-hormone which is a single polypeptide with an extra stretch called C-peptide.

·         C-peptide is removed during matured insulin.

·         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.

·         Chain A and chain B produced separately, extracted and combined by creating disulfide bonds to form mature human insulin.

 

Gene therapy:

• Gene therapy is an attempt to cure hereditary or genetic diseases.
• Genes are inserted into a person’s cells and tissue to treat the disease.
• The first clinical gene therapy was given in 1990 to a 4-yr old girl with adenosine deaminase (ADA) deficiency.
• This enzyme is required for breakdown of deoxyadenosine into uric acids.
• In the absence of ADA toxic deoxyadenosine is accumulated and destroy the infection fighting immune cells called T-cells and B-cells.
• This disorder is caused due to the deletion of the gene for adenosine deaminase in chromosome 20.

Treatment:

• Treated by bone marrow transplantation.
• Enzyme replacement therapy, involving repeated injections of the ADA enzyme
• Lymphocytes from the blood of the patient are grown in a culture. A functional ADA cDNA is then introduced into these lymphocytes and returned into the body.
• The patient required periodic infusion of genetically engineered lymphocytes because these cells are not immortal.
• Functional ADA cDNA introduced into cells at early embryonic stages, could be the permanent cure.

Molecular diagnosis:

• Early detection of disease is not possible by conventional methods (serum and urine analysis)

Molecular diagnosis techniques:

• Recombinant DNA technology.
• Polymerase chain reaction (PCR)
• Enzyme linked Immuno-sorbent Assay (ELISA)
• Very low concentration of a bacteria or virus can be amplified and detected by PCR.
• It used to detect genetic disorders.
• PCR is use full to mutation in genes in suspected cancerous patient:
• A single stranded DNA or RNA tagged with radioactive molecule (probe) is allowed to hybridize to its complementary DNA in a clone of cells followed by detection using autoradiography.
• The clone having mutated gene unable make complementary bonding of probe, hence not appears in photographic film.

TRANSGENIC ANIMALS:

• Animals that have an alien DNA which able to express in it is called transgenic animals.

Reasons for creation of transgenic animals:

• Normal physiology and development:
• Transgenic animals are specifically designed to allow study of:
• How the genes are regulated.
• How the gene affects normal functioning of body
• How it affects growth and development. E.g. insulin like growth factor.

 

• The animals made transgenic to know the biological effect and result.

 

• Study of disease:
• Transgenic animals are designed to understand how genes contribute to the development of disease like cancers, cystic fibrosis, rheumatoid arthritis and Alzheimer’s.

 

• Biological products:
• Transgenic animals are used to produce biological product of human interest:
• α-1-antitrypsin used to treat emphysema.
• Proteins for treatment for PKU and cystic fibrosis.
• Transgenic cow Rosie, produce human protein enriched milk (2.4 gm/lit. human α-lactalbumin)

 

• Vaccine safety:
• Transgenic mice are being developed and use in testing the safety of vaccines before they are used for humans.
• Polio vaccine is tested in mice.

 

• Chemical safety testing:
• This is also known as toxicity/safety testing.
• Transgenic animals are made to known the effect of toxic chemicals.

 ETHICAL ISSUES:

• GEAC (Genetic Engineering Approval Committee) set up by Indian Govt, which will make decisions regarding validity of GM research and safety of introducing GM-organisms for public services.
• A patent is the right granted by a government to an inventor to prevent others from commercial use of his invention.
• Patents granted for biological entities and for products derived from them; these patents are called biopatents.
• 27 documented varieties of Basmati are grown in India.
• Biopiracy is the term used to refer to the use/exploit or patent, of biological resources by multinational companies and other organizations without proper authorization from the countries and people concerned without compensatory payment.