BIOTECHNOLOGY AND ITS APPLICATIONS

Biotechnology improves crop production, enables safer therapeutics and diagnosis, creates transgenic animal models, and raises important questions of safety, ownership and benefit sharing.

Tissue culture regenerates whole plants from explants under sterile conditions because plant cells show totipotency. Micropropagation rapidly makes many identical plants (somaclones), while meristem culture can recover virus-free plants from infected plants.

• Somatic hybridisation fuses protoplasts. Tomato-potato fusion produced pomato, but it lacked the full commercially useful combination of characters.
• GM organisms have altered genes. GM crops can tolerate cold, drought, salt or heat; reduce post-harvest loss and pesticide use; improve mineral-use efficiency; and enhance nutrition, as in vitamin A-enriched golden rice.
• Bt crops carry selected cry genes from Bacillus thuringiensis. The inactive protoxin is activated in an insect's alkaline gut, lyses gut cells and kills susceptible larvae.

RNA interference (RNAi) is a eukaryotic cellular defence in which complementary double-stranded RNA silences a specific mRNA and prevents translation.

• Meloidogyne incognita is a root-infecting nematode of tobacco that reduces yield.
• Using an Agrobacterium vector, plants can be made to produce both sense and antisense RNA matching nematode genes. The complementary strands form dsRNA and trigger RNAi.
• The essential nematode mRNA is silenced, so the parasite cannot survive in the transgenic host.

Recombinant DNA technology enables mass production of safe therapeutic proteins that do not cause the unwanted immune responses associated with non-human sources.

• Earlier insulin was extracted from cattle or pig pancreas and could cause allergy. Human insulin has A and B polypeptide chains joined by disulphide bridges.
• Humans first make proinsulin, which has an extra C-peptide removed during maturation. Mature insulin has no C-peptide.
• In 1983, Eli Lilly introduced separate DNA sequences for human insulin A and B chains into E. coli. The separately produced chains were joined to form human insulin.

Gene therapy inserts a normal gene into cells or tissues to treat a hereditary disease by compensating for a defective gene.

• The first clinical gene therapy (1990) treated a four-year-old with ADA deficiency. Patient lymphocytes received ADA cDNA using a retroviral vector and were reintroduced; repeated treatment is needed because lymphocytes are not immortal.
• PCR detects a pathogen before symptoms by amplifying very small amounts of nucleic acid; it is used for HIV and mutation detection.
• ELISA detects pathogen antigens or antibodies by antigen-antibody interaction. Labelled DNA/RNA probes reveal complementary sequences through hybridisation and autoradiography.

Transgenic animals carry and express an extra foreign gene. Mice make up over 95% of existing transgenic animals, though rats, rabbits, pigs, sheep, cows and fish have also been produced.

• They reveal how genes regulate normal physiology and development and serve as models for cancer, cystic fibrosis, rheumatoid arthritis and Alzheimer's disease.
• They can make biological products, such as human alpha-1-antitrypsin for emphysema. Transgenic cow Rosie produced milk enriched with human alpha-lactalbumin.
• They support vaccine safety testing and toxicity testing, potentially reducing time and use of other animal models.

GM organisms can have unpredictable effects after environmental release, so their development and public use require regulation. In India, GEAC assesses GM research and safety.

• Biopiracy is use of bio-resources or traditional knowledge by companies or organisations without proper authorisation or compensation.
• Indian Basmati, turmeric and neem illustrate why traditional knowledge and biodiversity need protection against unfair patent claims.
• Ethical biotechnology requires safety assessment, informed regulation and fair benefit sharing.

• Tissue culture uses totipotency; micropropagation produces somaclones.
• Bt crops use cry genes; RNAi silences a parasite's specific mRNA.
• Recombinant human insulin is assembled from A and B chains produced in bacteria.
• ADA deficiency illustrates gene therapy; PCR, ELISA and probes support early diagnosis.
• Transgenic animals aid research, production and testing; GEAC and biopiracy are key ethical topics.