Biotechnology and its Applications

Imagine cotton plants that make their own insect killer, so bollworm dies when it eats leaf. That's Bt cotton.

Bacillus thuringiensis bacteria makes Cry crystal protein - natural insecticide. Scientists took its cry genes cryIAb and cryIIAb and put into cotton. Now cotton plant itself makes Cry protein.

Why Bt safe for us? Cry protoxin inactive, needs alkaline pH in insect gut to activate, then binds gut receptor, makes pores, insect dies. Human stomach is acidic, so safe.

Bt cotton first GM crop approved in India 2002, saves pesticide, increases yield.

Root-knot nematode Meloidegyne incognitia attacks tobacco roots, makes knots, plant dies.

Solution: RNAi - RNA interference. Make plant produce double-stranded RNA (dsRNA) that matches nematode gene. When nematode eats plant, dsRNA enters, silences nematode mRNA, so nematode cannot make important protein and dies.

Method: Agrobacterium vector carries sense + antisense DNA, makes dsRNA in host cells. This is pest control without chemical.

Diabetes patients need insulin. Earlier insulin from pigs/cows caused allergy.

Human insulin has A chain 21 amino acids and B chain 30 amino acids linked by disulfide bonds. Proinsulin has extra C-peptide that is removed to make mature insulin.

How made? Scientists made genes for A and B chains separately, put into E.coli plasmids, E.coli makes A and B chains separately as inclusion bodies, then extracted and joined by disulfide bonds A7-B7 and A20-B19.

First recombinant human insulin called Humulin by Eli Lilly 1983, first FDA approved rDNA drug.

ADA = Adenosine Deaminase enzyme needed for immune system. If ADA gene defective, child has SCID - Severe Combined Immuno Deficiency, no immunity, dies early - bubble baby.

Gene therapy: Take bone marrow lymphocytes from patient, infect with retroviral vector carrying normal ADA cDNA, grow cells, inject back into patient. Cells make ADA, immunity improves.

But not permanent cure - lymphocytes die, need repeat infusion. Permanent cure if bone marrow stem cells corrected at early embryonic stage.

Early detection important because low pathogen concentration missed by conventional methods.

PCR: Polymerase Chain Reaction amplifies DNA billions times 2^n, detects very low concentration of HIV virus early, before symptoms.

ELISA: Enzyme Linked Immunosorbent Assay - antigen-antibody reaction, color change if antigen present. Used to detect infections, hormone levels.

Both are sensitive, early, accurate.

Transgenic animals have foreign gene inserted and expressed.

Rosie - first transgenic cow 1997 - had human alpha-lactalbumin gene, milk enriched 2.4g/L human protein, more nutritious for babies.

Other uses: transgenic mice to study genes, test vaccines, sheep produce therapeutic proteins in milk.

Benefits: study normal physiology, vaccine safety, disease models, biological products.

Biotechnology can harm - need ethics and rules.

GEAC = Genetic Engineering Approval Committee - Indian government body under Environment Protection Act 1986, approves GM crops trials, monitors safety.

Biopiracy: Using other country's traditional knowledge without permission and patenting. Example: Turmeric US patent 1995 for wound healing revoked 1997 after India proved traditional use, Neem patent 1994 revoked 2000, Basmati rice patent by RiceTec 1997 revoked 2001.

Biopatent: Patent on biological resources genes. Need benefit sharing with local communities. Nagoya Protocol, TKDL Traditional Knowledge Digital Library to protect.

Bt Brinjal controversy: GEAC approved 2009 first GM food crop, but protests about health safety biodiversity farmer dependency, government imposed moratorium 2010.