What are transgenic animals ? Give the application of transgenic Animals
Answer :
- It is now possible to carry out manipulations at genetic level to get the desired characteristics in animals.
- Transgenesis refers to the phenomenon of introduction of exogeneous DNA into the genome of an organism.
- The foreign DNA that is introduced is called as 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 its germ line.
- The animals used for transgenesis include rat, rabbit, pig, cow, goat, sheep, fist etc.
- Mouse is the animal of choice for transgenic experiments because they have short generation time.
- It produces more eggs, normal mouse produces 5-10 eggs, superovulated mouse can yield upto 40 eggs.
- More than 95% of transgenic aninmals are mice.
Methods of Transgenesis
a) Transfer of whole nucleus from a somatic cell of a donor into the enucleated egg of the recipient animal.
b) Transfer of a part of bisected embryo into the enucleated unfertilised egg.
c)Transter of chromosome or chromosomal fragments etc.
Application of transgenic animals.
- Transgenic animals have great benefits to mankind.
- Due to transgenesis their is improvement in 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 models for human diseases like cancer, cystic fibrosis, rheumatoid arthritis, Alzheimers disease etc. new methods of their treatment is possible.
- Vaccine safety : Transgenic mice are 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 transgenic animals are useful to produce d-1-antitrypsin which used to treat emphysema.
- Similarly phenylketonuria (pKu) is being treat. In 1997 the first transgenic cow produced called 'Rosie.
- This cow produced human protein enriched milk (2-4 gms/litre).
- This is nutritionaly more balanced milk product than natural cow milk.
- Chemical safety testing : Transgenic animals with foreign genes are produced consequently the transgenic animals become more sensitive to toxic chemicals.
- These animals are exposed to toxic chemicals, toxicity testing in such animals gives fast result.
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