Short Notes: Biotechnology & its Applications

Table of Contents
1. Bt Cotton
2. Transgenic Animals
3. Gene Therapy
4. RNA Interference (RNAi)
5. Insulin Production
6. Other Products from Biotechnology
7. Ethical, Social and Safety Issues
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Bt Cotton

Bt cotton is a genetically modified cotton variety carrying a gene from the soil bacterium Bacillus thuringiensis. The inserted gene encodes a crystalline protein (commonly called a Cry or Bt toxin) that is toxic to certain lepidopteran pests when ingested. The plant expresses the toxin in its tissues so that feeding larvae are killed, reducing damage to bolls and increasing effective yield.

• Mode of action: Ingested Bt toxin binds to specific receptors in the insect midgut, creating pores in the gut cells, causing paralysis and death of larvae.
• Benefits: Reduced use of chemical insecticides; lower production cost; increased yield and farmer convenience.
• Resistance management: Refuge planting (non-Bt plants) and other strategies are recommended to delay pest resistance development.
• Concerns: Environmental and biosafety issues such as effects on non-target organisms, possible development of resistant pest strains, and socio-economic considerations for farmers.

Transgenic Animals

Transgenic animals are animals whose genomes have been altered by introduction of foreign genes. They serve multiple roles in medicine, agriculture and research by acting as bioreactors, disease models and tools for understanding gene function.

• Gene therapy: Transgenic approaches are related to gene therapy methods used to correct genetic defects at the organismal level.
• Production of biologicals: Animals engineered to express human proteins in milk, blood or eggs can be used to produce therapeutic proteins; an example is production of α-1-antitrypsin in sheep milk for treating human disorders.
• Vaccine production: Transgenic animals can be used as bioreactors to make vaccine components and other biologically active molecules.
• Disease models: Transgenic and knockout animals (for example, mice) are widely used to study human diseases, test drugs and understand gene function.

Gene Therapy

Gene therapy aims to treat or prevent disease by introducing, replacing or silencing genes in a patient's cells. It can be performed ex vivo (cells removed, modified and returned) or in vivo (direct delivery into the body). Vectors used include viral vectors (retrovirus, lentivirus, adeno-associated virus) and non-viral methods (plasmids, nanoparticles).

• Example: Treatment of adenosine deaminase (ADA) deficiency in severe combined immunodeficiency involved transfecting patient lymphocytes with a functional ADA gene to restore enzyme activity.
• Limitations and risks: Insertional mutagenesis, immune responses to vectors, transient expression and delivery challenges.
• Current focus: Improving safety, targeted delivery, durable expression and regulatory oversight for clinical use.

RNA Interference (RNAi)

RNA interference (RNAi) is a natural cellular process used to silence specific genes using double-stranded RNA (dsRNA). Dicer enzyme processes dsRNA into small interfering RNAs (siRNAs), which are incorporated into the RNA-induced silencing complex (RISC) to target and degrade complementary mRNA, preventing protein production.

• Application in plants: RNAi has been used to confer resistance against pests and pathogens; for example, tobacco plants engineered to express dsRNA targeting genes of the root-knot nematode Meloidogyne incognita show reduced infection.
• Therapeutic uses: RNAi is being explored for silencing disease genes in human therapy and for antiviral and anticancer approaches.

Insulin Production

Recombinant human insulin is produced by inserting the human insulin gene into microorganisms. Early recombinant methods expressed the A and B polypeptide chains separately in Escherichia coli and chemically combined them to form active insulin. Later improvements allowed expression of human proinsulin that could be enzymatically processed to mature insulin in host cells.

• Advantages: Pure human insulin preparation, reduced risk of allergic reactions compared with animal-derived insulin, large-scale and cost-effective production.
• Hosts: Bacteria (E. coli) and yeast are commonly used production systems.

Other Products from Biotechnology

Biotechnology enables production of many medically important proteins and vaccines using recombinant DNA technology and cell culture methods.

• Human growth hormone (hGH): Recombinant hGH is used to treat growth hormone deficiency and certain growth disorders.
• Interferons: Antiviral and immunomodulatory proteins used in treatment of viral infections and some cancers.
• Tissue plasminogen activator (TPA): A thrombolytic enzyme used to dissolve blood clots in myocardial infarction and ischaemic stroke.
• Hepatitis B vaccine: Recombinant vaccine produced by expressing hepatitis B surface antigen (HBsAg) in yeast cells; safer than earlier plasma-derived vaccines.

Ethical, Social and Safety Issues

Biotechnology raises scientific, ethical and regulatory questions that require careful consideration and oversight to ensure safety, equity and environmental protection.

• Biopiracy and biopatents: Concerns about patenting biological resources and traditional knowledge without fair benefit sharing.
• GM food safety: Issues include potential allergenicity, gene flow to wild relatives, long-term ecological effects and the need for rigorous safety testing.
• Animal welfare: Ethical treatment of transgenic animals used in research and production, including pain, suffering and husbandry concerns.
• Regulation and monitoring: Importance of biosafety guidelines, field trials, post-release monitoring and clear labelling and public communication.