Genetically Modified Animals and Transgenic Animal Techniques
Science & Technology › Biotechnology – Applications · Topic 11.2
A transgenic animal is an animal that carries a foreign gene, called a transgene, in all its cells, inserted by genetic engineering and passed to its offspring. The main techniques are pronuclear microinjection of DNA into a fertilised egg, the use of genetically modified embryonic stem cells, retroviral vectors, somatic cell nuclear transfer, and now gene editing with CRISPR. Transgenic animals are used as models of human disease, such as mice with cancer genes, as bioreactors that make drugs in their milk, as sources of organs, and for improved food animals. The first transgenic mice were made in 1974 and 1980 to 1982, and Dolly, the first mammal cloned from an adult cell, was born in 1996.
5 min read · UPSC Prelims · Science & Technology · Biotechnology – Applications
At a Glance
- Core idea Foreign gene in the animal genome
- Methods Microinjection, stem cells, cloning
- First cloned mammal Dolly, 1996
- Uses Models, drugs, food
- Regulation RCGM and GEAC
- Exam link UPSC Prelims, Science & Technology: Biotechnology – Applications
Where Does It Fit?
This topic follows genetically modified plants. It applies the same tools to animals, where the aims include medicine, research and food, and the ethical concerns are sharper. Previous topic: Genetically Modified Plants and Pest-Resistant Crop Technologies. Next topic: Bioremediation and Microbial Remediation.
How Are Transgenic Animals Made?
| Technique | How it works |
|---|---|
| Pronuclear microinjection | Copies of the transgene are injected into the nucleus of a fertilised egg, which is then placed in a surrogate mother. Integration is random and often fails |
| Embryonic stem cell method | The gene is introduced into cultured embryonic stem cells and checked. Good cells are put into an early embryo. Used to make knockout mice |
| Retroviral vector | A modified virus carries the gene into early embryo cells |
| Somatic cell nuclear transfer | The nucleus of a modified body cell is put into an egg without its own nucleus and the embryo is grown. Used to clone Dolly |
| Sperm mediated transfer | Sperm carry the DNA into the egg during fertilisation |
| Gene editing | CRISPR changes specific genes in embryos, giving more precise and efficient results |
| Selection and breeding | Founders are tested and bred to get a line with stable inheritance of the transgene |
What Are the Uses of Transgenic Animals?
- Disease models: mice with human disease genes are used to study cancer, diabetes and Alzheimers disease. The knockout mouse method earned Mario Capecchi, Martin Evans and Oliver Smithies the 2007 Nobel Prize
- Drugs from milk: goats, sheep or cows make human proteins in their milk, such as antithrombin from goats, an approved anticoagulant
- Organ donation: pigs edited to reduce rejection are tested as a source of organs, as in Xenotransplantation: Animal Organs for Human Patients
- Improved food animals: the AquAdvantage salmon grows faster and was approved in the United States in 2015
- Disease resistance: animals are edited to resist infections, for example pigs resistant to a respiratory virus
- Safety testing: transgenic mice are used to test the safety of vaccines and drugs
- Conservation and cloning: cloning helps to multiply elite or rare animals
- Environmental sensing: animals engineered to glow under pollution have been tested in research
What Else Should You Remember?
- Dolly: born in 1996 at the Roslin Institute in Scotland by nuclear transfer from an adult cell. She died in 2003
- Indian clones: the National Dairy Research Institute at Karnal cloned a buffalo calf, Samrupa, in 2009 and a cow clone named Garima was born in 2010. Noori, a pashmina goat, was cloned in Kashmir in 2012
- GalSafe pig: a gene edited pig approved by the United States regulator in 2020 for food and medical use, as it lacks a sugar that causes allergy
- Knockout and knock-in: a knockout animal has a gene disabled, and a knock-in has a gene replaced or added
- Chimera: an animal made of cells from two embryos is a chimera, and is different from a transgenic animal
- Oncomouse: a mouse with a cancer gene was the first patented animal, granted in the United States in 1988
- Efficiency problem: the success rate of cloning and microinjection is low, and many embryos or offspring have defects
- Animal welfare: suffering of animals is a main ethical concern, so the 3Rs rule of replace, reduce and refine applies
- Indian rules: research on transgenic animals follows the 1989 Rules under the Environment (Protection) Act and the guidelines of the Committee for Control and Supervision of Experiments on Animals
- Biosafety: escape of engineered animals could affect wild populations, so containment is needed, as in Biosafety Protocols
- Gene drives: a method that spreads a gene through a population is being studied for insect control, as in Genetically Modified Mosquito for Vector Control
- Link: genes for drugs made in milk are inserted by methods in Recombinant DNA technology Cutting tool Restriction enzymes Joining tool DNA ligase Carriers Plasmids and other vectors India…">Genetic Engineering: Procedure and Applications
Why Does It Matter for the Exam?
- Methods: microinjection, stem cells, SCNT
- Facts: Dolly and Indian clones
- Uses: disease models and milk proteins
- Current affairs link: pig organ transplants and gene edited animals
- Common errors: confusing transgenic animals with clones
As an analytical point, transgenic animals are essential for medical research but raise animal welfare and biosafety issues. Strong oversight and the 3Rs approach allow progress while limiting harm.
Why Is This Topic Important?
- Methods Techniques asked
- Uses Medicine and food
- Ethics Welfare and safety
What Came Next?
The next topic covers bioremediation and the use of microbes to clean pollution. Next topic: Bioremediation and Microbial Remediation.
Key People and Terms
- Transgene Foreign gene
- Knockout Gene disabled
- SCNT Nuclear transfer for cloning
- Founder First transgenic animal
- Chimera Mix of cells from two embryos
- Bioreactor animal Animal producing drug
Exam Corner
Points to Remember
- Dolly: 1996, Roslin Institute.
- Samrupa buffalo clone: 2009, NDRI Karnal.
- Knockout mouse Nobel: 2007.
- Oncomouse patent: 1988.
- AquAdvantage salmon approved: 2015.
Do Not Confuse With
- Transgenic animal and clone Foreign gene added versus genetic copy
- Knockout and knock-in Gene removed versus gene added
- Transgenic animal and chimera Gene in every cell versus mix of two cell types
Memory Hook
Inject the egg, edit the stem cell, move the nucleus; Dolly proved the last.
Mains Angle
Questions ask about the methods, uses and ethics. These points help.
- Uses Models and drugs
- Concerns Welfare and safety
- Rules Oversight
A Question You May Face
An original practice question, not a past paper question.
“Discuss the applications and ethical concerns of transgenic animal technology and the regulatory safeguards required.”
How to Answer
- Methods Microinjection, SCNT.
- Uses Models, drugs, food.
- Concerns Welfare, biosafety.
- Way 3Rs and rules.
GS Relevance
Frequently Asked Questions
What is a transgenic animal?
A transgenic animal is an animal that carries a foreign gene, called a transgene, in all its cells, introduced by genetic engineering and passed on to its young. Transgenic animals are used as disease models, as producers of drugs in their milk, and sometimes as improved food animals or organ sources.
How is a transgenic animal made by microinjection?
In pronuclear microinjection, copies of the desired gene are injected into the nucleus of a fertilised egg using a fine needle. The egg is then placed in the uterus of a surrogate mother, and offspring are tested for the gene. The success rate is low because the gene inserts at random positions.
Who was Dolly?
Dolly was a sheep born in 1996 at the Roslin Institute in Scotland, the first mammal cloned from an adult cell. She was created by somatic cell nuclear transfer, in which the nucleus of an udder cell was placed into an egg whose own nucleus had been removed. She died in 2003.
What are knockout mice?
Knockout mice are mice in which a chosen gene has been disabled using embryonic stem cell technology. They help scientists to learn what the gene does and to model human diseases. Mario Capecchi, Martin Evans and Oliver Smithies received the 2007 Nobel Prize in Physiology or Medicine for developing the method.
Which Indian animals have been cloned?
The National Dairy Research Institute at Karnal produced the first cloned buffalo calf, Samrupa, in 2009 and a cloned cow named Garima in 2010. In 2012 scientists in Kashmir cloned a pashmina goat named Noori. These clones were made by somatic cell nuclear transfer and showed that India had the technique.
PYQ Practice — Statement Analysis
1 Dolly was the first mammal cloned from an adult cell.
Born in 1996.
2 In a knockout animal, a gene is disabled.
Used for disease models.
3 Pronuclear microinjection injects DNA into the nucleus of a fertilised egg.
A standard method.
4 Samrupa was a cloned sheep.
It was a cloned buffalo calf.
Past Mains Questions on This Topic
This topic comes under Biotechnology – Applications. UPSC Mains questions asked on the matching syllabus topic, year-wise with marks:
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