Biotechnology and Its Applications

Biotechnology and Its Applications

1. Biotech Research Areas, Agricultural Applications & GMOs

A. Three Critical Research Areas of Biotechnology

1. Providing Best Catalyst: Supplying improved biological organisms (usually a microbe or pure enzyme).
2. Creating Optimal Conditions: Engineering optimal environment for the catalyst to act efficiently.
3. Downstream Processing: Purifying proteins and organic compounds on a commercial scale.

B. Applications in Agriculture & Tissue Culture

• Green Revolution (1960s): Tripled food production via HYV seeds and agrochemicals, but high cost and pollution remained limitations. (Father of Green Revolution in India: M.S. Swaminathan).
• Tissue Culture (In-vitro propagation): Technique developed in 1950s where a whole plant is regenerated from an explant in a test tube.• Totipotency: Capacity to generate a whole plant from any cell/explant. Requires carbon source (sucrose), inorganic salts, vitamins, amino acids, and growth regulators (auxin, cytokinin).

  • Micropropagation: Producing thousands of plants rapidly; produces genetically identical Somaclones (e.g., Banana, Apple, Tomato).

  • Virus-Free Plants: Meristem (apical/axillary) is free of virus and used as explant (e.g., Sugarcane, Banana, Potato).

  • Somatic Hybridization: Isolation of naked protoplasts (cell wall digested) from two plant species and fusing them to form somatic hybrids (e.g., Pomato = Potato $+$ Tomato; commercially unsuccessful).

C. Genetically Modified Organisms (GMO) & Golden Rice

• Key Advantages of GM Crops: Enhanced tolerance to abiotic stresses (cold, drought, salt), reduced reliance on chemical pesticides, decreased post-harvest losses, increased mineral usage efficiency, and enhanced nutritional value.
• GMO Approaches: Gene Addition (adding desirable trait) or Gene Subtraction / Silencing (removing unnecessary/harmful gene).
• Golden Rice (Vitamin A Enriched Rice): Developed by Ingo Potrykus & Peter Beyer. Genes coding for $\beta$-carotene (provitamin A) transferred from Daffodil plant and bacteria into rice using Agrobacterium vector to cure Night Blindness and Xerophthalmia.

2. Pest-Resistant Plants, Bt Toxin & RNA Interference (RNAi)

A. Bt Cotton & Mechanism of Bt Toxin Action

• Produced by soil bacterium Bacillus thuringiensis. Contains insecticidal crystal protein encoded by cry genes.
• Mode of Action: Injected or ingested as inactive protoxin $\to$ Ingested by insect $\to$ Solubilized in alkaline pH of insect midgut $\to$ Converted to active toxin $\to$ Binds to midgut epithelial cells $\to$ Creates pores causing cell swelling, lysis, and insect death.
• Specific Cry Genes:• cryIAc & cryIIAb: Controls Cotton Bollworms.

  • cryIAb: Controls Corn Borer.

• Insect Target Groups: Lepidopterans (tobacco budworm, armyworm), Coleopterans (beetles), Dipterans (flies, mosquitoes).

B. Transgenic Hirudin & Flavr Savr Tomato

• Transgenic Hirudin: Synthetic gene for anticoagulant Hirudin (from leech Hirudinaria) introduced into oilseed plant Brassica napus via Agrobacterium; extracted and purified from seeds.
• Flavr Savr Tomato: Gene silencing of Polygalacturonase enzyme (which degrades pectin in cell walls) extends shelf life and delays fruit softening.

C. RNA Interference (RNAi / Gene Silencing)

A natural cellular defense mechanism present in all eukaryotic organisms taking place at the post-transcriptional level:

• Target Pathogen: Nematode parasite Meloidogyne incognita infects roots of Tobacco plants, causing root knot disease and severe yield loss.
• Mechanism: Nematode-specific genes introduced into host plant via Agrobacterium vectors $\to$ Produces both sense and anti-sense RNA in host cells $\to$ Form complementary double-stranded RNA (dsRNA).
• dsRNA triggers silencing of specific mRNA of nematode via RNA-induced silencing complex (RISC) $\to$ Prevents translation of vital proteins $\to$ Nematode cannot survive in transgenic host!

3. Genetically Engineered Insulin & Gene Therapy

A. Production of Recombinant Human Insulin (Humulin)

• Insulin is a proteinaceous hormone secreted by $\beta$-cells of Islets of Langerhans (gene on Chromosome 11). Controls blood glucose levels; deficiency causes Diabetes Mellitus.
• Pro-Insulin vs. Active Insulin: Pro-insulin contains A-chain (21 aa), B-chain (30 aa), and an extra C-peptide chain. Processing involves removal of C-peptide to yield active insulin joined by disulfide bonds.
• Eli Lilly Breakthrough (1983): American company prepared two DNA sequences corresponding to A and B chains of human insulin $\to$ Introduced into plasmids of E. coli to produce chains separately $\to$ Extracted and combined by creating disulfide bonds to form functional Humulin.

B. Gene Therapy (ADA Deficiency Case Study)

Collection of methods allowing correction of a gene defect diagnosed in a child/embryo.

• First Clinical Attempt (1990): Performed on a 4-year-old girl with Adenosine Deaminase (ADA) Deficiency (leads to Severe Combined Immunodeficiency – SCID due to lack of functional T-lymphocytes).
• Treatment Options Comparison:• Enzyme Replacement Therapy (ERT): Intravenous injection of functional ADA enzyme (Temporary, not permanent).

  • Bone Marrow Transplant: Functional cells transplanted (Not fully curative/permanent).

  • Gene Therapy Protocol: Lymphocytes isolated from patient’s blood $\to$ Functional ADA cDNA introduced using Retroviral vector $\to$ Cells returned to patient. (Requires periodic infusion as WBCs are not immortal).

  • Permanent Cure: Gene isolated from marrow cells producing ADA introduced into cells at early embryonic stages!

4. Molecular Diagnostics & Comparative Diagnostic Methods

A. Pathophysiology & Diagnostic Approaches

Pathophysiology is the study of altered body functions caused by disease. Conventional methods only detect pathogens after symptoms appear when pathogen concentration is high.