Pest resistant plants –

• A nematode Meloidogyne incognita infects the roots of tobacco plants which reduces the production of tobacco.
• It can be prevented by using RNA interference (RNAi) process which is checked by silencing of specific mRNA due to complements dsRNA.
• DsRNA binds and prevent translation of the mRNA (silencing)
• By using agrobacterium vectors, nematode -specific genes were introduced into the host plants which produce both sense and antisense RNA in the host cells.
• These two RNAs are complementary to each other and form a double – stranded RNA (dsRNA) that initiates RNAi and silences the specific mRNA of the nematode.
• The parasites cannot survive in the transgenic host,
• So protects the plants from pests.

Biotechnological Applications in medicine :-

• The recombinant DNA technology is used for production of therapeutic drugs which are safe and effective.
• It avoids unwanted immunological responses, commonly observed with similar products isolated from non- human resources
• About thirty recombinant therapeutics have been approved for human use in the world including india.

Genetically engineered Insulin :-

• Insulin contains two short polypeptide chains – chain A and chain B linked by disulphide bridges.
• In mammals, insulin is synthesized as a pro – hormone ( that needs to be processed to become mature and functional hormone ). It contains an extra stretch called C peptide.
• C peptide is absent in mature insulin and is removed during maturation into insulin.
• Earlier ,insulin was extracted from pancreas of slaughtered cattle and pigs but some patients began developing allergies.
• Production of insulin by rDNA techniques was achieved by an American company,Eli lilly , in 1983. It prepared two DNA sequences corresponding to A and B chains of human insulin and introduced them in plasmids of coli for production.
• The A and B chains produced, were separated, extracted and combined. By creating disulfide bonds to form human insulin.