What are transgenic animals? Give the application of transgenic Animals
- It is now possible to carry out manipulations at the genetic level to get the desired characteristics in animals.
- Transgenesis refers to the phenomenon of the introduction of exogenous DNA into the genome of an organism.
- The foreign DNA that is introduced is called a transgene.
- The animal whose genome is altered by adding one or more transgenes is said to be transgenic.
- Thus transgenic organisms are genetically engineered or genetically modified organisms, with a new heritable character.
- Transgenic animals are fertile and carry the transgene in their germ line.
- The animals used for transgenesis include rats, rabbits, pigs, cows, goats, sheep, fists, etc.
- Mouse is the animal of choice for transgenic experiments because they have a short generation time.
- It produces more eggs, a normal mouse produces 5-10 eggs, and the superovulated mouse can yield up to 40 eggs.
- More than 95% of transgenic animals are mice.
Methods of Transgenesis
- Transfer of the whole nucleus from a somatic cell of a donor into the enucleated egg of the recipient animal.
- Transfer of a part of the bisected embryo into the enucleated unfertilized egg.
- Transfer of chromosome or chromosomal fragments etc.
Application of transgenic animals.
- Transgenic animals have great benefits to mankind.
- Due to transgenesis, there is an improvement in the quality and quantity of milk, meat, eggs, etc.
- Study of diseases: Many transgenic animals help us to understand how genes contribute to the development of disease.
- With the help of these animals which acts as a model for human diseases like cancer, cystic fibrosis, rheumatoid arthritis, Alzheimer’s disease, etc. new methods of their treatment is possible.
- Vaccine safety: Transgenic mice are the first to be used to test a newly discovered vaccine before it is used on human beings. Ex. Polio vaccine
- Bioreactors: By transgenesis, the animals are genetically modified in such a way that they act as bioreactors.
- Such animals are useful to produce d-1-antitrypsin which is used to treat emphysema.
- Similarly, phenylketonuria (PKU) is being treated. In 1997 the first transgenic cow was produced called ‘Rosie.
- This cow produced human protein-enriched milk (2-4 gms/liter).
- This is a nutritionally more balanced milk product than natural cow milk.
- Chemical safety testing: Transgenic animals with foreign genes are produced consequently the animals become more sensitive to toxic chemicals.
- These animals are exposed to toxic chemicals, and toxicity testing in such animals gives fast results.