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.
· 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.
Molecular diagnosis techniques:
Reasons for creation of transgenic animals:
Biotechnology is the branch of science where living organisms are used to improve the quality of product. Genetic engineering or recombinant DNA technology are the tools of biotechnology where genetic material or DNA of the host organisms is used to obtain product.