What is transgenesis? Describe the methods and applications of transgenesis in animals. (IAS 2021/20 Marks)

Transgenesis

• Transgenesis is the process of introducing foreign DNA into the genome of an organism, resulting in a transgenic organism that expresses a new trait or characteristic.
• Mechanism: This foreign DNA (transgene) is integrated into the host's DNA, allowing the organism to inherit and express the new genetic material in subsequent generations.
• Key Terms:
  
  • Transgenic Organism: An organism that has been genetically modified to contain a gene or genes from another species.
  • Transgene: The gene or genetic material that has been transferred into the organism.

Methods of Transgenesis in Animals

• Microinjection:
  
  • Direct injection of DNA into the nucleus of a fertilized egg.
  • Example: Used in the creation of transgenic mice, where a desired gene is microinjected into the pronucleus of a fertilized oocyte.
• Viral Vectors:
  
  • Utilization of viruses to deliver transgenes into host cells.
  • Example: Lentiviral vectors are commonly used to create transgenic models for studying diseases such as HIV and cancer.
• Embryonic Stem Cell (ESC) Technology:
  
  • Involves the modification of embryonic stem cells, which are then injected into a blastocyst, resulting in chimeric organisms.
  • Example: Mice with specific gene knockouts have been created using this technique for studying gene function and disease.
• CRISPR-Cas9 Technology:
  
  • A revolutionary genome-editing tool that allows for precise modifications of DNA in living organisms.
  • Example: Used to create genetically modified animals for various purposes, including disease modeling and agriculture.

Applications of Transgenesis in Animals

• Biomedical Research:
  
  • Example: Transgenic mice are used as models for human diseases, allowing researchers to study disease mechanisms and test therapies.
• Agricultural Improvements:
  
  • Example: Transgenic livestock can be engineered for desirable traits, such as increased growth rates, disease resistance, or improved milk production. For instance, the "Enviro-Pig," a transgenic pig developed to digest phosphorus more efficiently, reduces environmental pollution from manure.
• Pharmaceutical Production:
  
  • Example: Animals such as goats and cows have been genetically modified to produce proteins or antibodies for therapeutic use. The "pharming" approach utilizes transgenic animals to produce complex human proteins, such as antithrombin, in their milk.
• Conservation Biology:
  
  • Example: Transgenesis can be used to enhance the survival of endangered species through techniques like gene editing for disease resistance or increased adaptability to climate change.
• Modeling Human Diseases:
  
  • Example: Transgenic animals can be created to express human genes linked to specific diseases, providing valuable insights into pathology and potential treatments.

Conclusion

Transgenesis in animals is a powerful tool that has revolutionized the field of genetics and has numerous applications in research, medicine, and agriculture. By introducing foreign genes into the genomes of animals, scientists can study gene function, develop animal models for human diseases, and produce genetically modified organisms with desirable traits.