Transgenic Organisms and Transgenic Animals
What is a Transgenic Organism?
- A transgenic organism, also known as a genetically modified organism (GMO), is an organism whose genetic material has been intentionally altered through the use of recombinant DNA technology.
- These modifications involve the insertion of foreign DNA into the genome to introduce new traits or produce specific proteins.
- The process is widely applied in biotechnology for research, medicine, and industrial production.
Applications of Transgenic Organisms
- 1. Production of Recombinant Proteins
- Transgenic organisms are crucial in the production of medically valuable proteins such as human insulin and growth hormones.
- Before recombinant technology, these proteins were harvested from natural sources like animal organs or human cadavers, which posed risks and were inefficient.
- 2. Genetically Modified Bacteria
- Bacteria like E. coli are frequently used to produce recombinant proteins.
- However, bacteria cannot perform the post-translational modifications needed for the functionality of many eukaryotic proteins.
- 3. Transgenic Yeasts and Mammalian Cells
- Yeasts are better suited for producing more complex proteins because they can perform some post-translational modifications.
- Cultured mammalian cells provide an even closer match to human protein processing, and are used to produce vaccines and therapeutic proteins.
Transfection Techniques in Animal Cells
The process of introducing foreign DNA into animal cells is known as transfection, which is similar to transformation in bacteria. Several sophisticated techniques are used:
- 1. Electroporation
- A short electrical pulse temporarily opens the cell membrane, allowing DNA to enter.
- Can be applied directly to tissues and is commonly used in laboratory experiments.
- 2. Calcium Phosphate Precipitation
- A DNA-calcium-phosphate mixture forms precipitates that cells take in by endocytosis.
- Simple and cost-effective, though efficiency may vary.
- 3. Cationic Polymer Transfection
- DNA is combined with positively charged polymers, forming complexes that enter cells via endocytosis.
- Offers higher efficiency and low toxicity.
- 4. Liposome Fusion
- DNA is enclosed in artificial lipid vesicles called liposomes.
- These vesicles merge with the cell membrane and release DNA into the cytoplasm.
- 5. Microinjection
- DNA is directly injected into the nucleus using a fine glass needle.
- It allows for precise control and is often used in the creation of transgenic animals.
- Although time-consuming, it is one of the most accurate methods.
- 6. Viral Vector Transduction
- Viruses are engineered to carry therapeutic or experimental genes into cells.
- Two main types:
- Adenoviral Vectors: Carry double-stranded DNA into cells efficiently without integrating into the host genome. Good for short-term expression.