“Transgenic Animals & Its Production Methods”

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Transgenic animals are commonly known as “Genetically Engineered Organism” (GEO) or “Genetically Modified Organism” (GMO). The advancement in biological science to produce genetically modified animals by introducing a foreign gene into the animal germ-line has raised the strength of bioresearch to an unexpected level (Datta, S., et al, 2018). The transgenic technique gives a very beneficial method to quickly introduce modified genes into the host genome without cross-breeding (Mohammed, F., et al, 2016). The transgenic technology emergence has broadened the development scope in the farm animal’s case and the arrival of new techniques of molecular biology have paved the way by giving the latest aspects to animal breeding (Rajoriya. R., et al., 2013).

What are transgenic animals?

The transgenic animal is a modified animal that carrying a modified gene that has been intentionally admitted into an animal genome. Transgenesis refers to Complementary Deoxyribonucleic Acid (cDNA) insertion that is made from Messenger Ribonucleic Acid (mRNA) into the cells. Animal’s characteristics are altered by genetically to have particular characteristics (Rajoriya. R., et al., 2013).

Why produce transgenic animals?

The development of genetically modified animals have been the biotechnology research part now extending very rapidly.  Interest in genetically modified animals fall into various categories:

  • Transgenic animals are produced for manufacturing good and better quality breed, milk yield increase and also for organ transplantation.
  • Transgenic animals play a vital role in the production of new treatments for various diseases (Singhal & Kansara 2010).
  • In a short period, the production efficiency of farm animals is increase.
  • Nutraceuticals are also produced by GMOs.
  • Transgenic animals are mostly utilized as food sources, scientific models, xenotransplanters, and disease models (Rajoriya. R., et al., 2013).

Methods for Production of Transgenic Animal:

The field of biotechnology has moved forward to the level where it is normally possible to make a specific alteration to the host's genome. The field of biotechnology has moved forward to a level where it is normally possible to make a specific alteration to the host genome (Singhal & Kansara., 2017). Three different techniques are commonly used to produce genetically modified animals, namely:

  1. DNA microinjection
  2. Embryonic Stem Cell-Mediated Gene Transfer
  3. Retrovirus mediated gene transfer


1.    DNA Microinjection:

DNA microinjection is the most common and first transgenic method that proved to be effective in mammals. These all materials are required namely a glass needle (microcapillary pipette), a micro-injector, and a positioning device that regulates the micropipette movement. In this method, a combination of genes or a single gene from another member of the different or from the same species will be constructed and directly injected into the pro-nucleus (male) of an impregnated ovum. The transgene is injected in the male pro-nucleus because of its large size than the pro-nucleus of the female. Manipulated fertilized ovum is introduced in the oviduct of a recipient or foster mother that has been synchronized (Datta, S., et al, 2018).

Advantages:

  • Doesn’t required protoplast
  • Very efficiently foreign genetic material is expressed.
  • No size limit of the injected DNA fragment.
  • This process is cheap.
  • Method is simple or precise.
  • This method is used for a broad variety of species.

2.    Embryonic Stem Cell-Mediated Gene Transfer:

Embryonic stem (ES) Mediated Gene Transfer is a second technique for the production of transgenic animals and introduces a transgene to a particular site into the host genome. This method involves the prior injection of desired foreign DNA by microinjection, chemicals, a virus, or homologous recombination into in-vitro embryonic stem (ES) cell culture. ES cells are collected from the ICM of blastocysts. These cells grow inside the culture and retain their capability to produce mature animal cells, with its gametes. Inject the target gene or vector into the ES cells. Then select successfully transformed or manipulated cells. Again inject manipulated cells into the host blastocyst and transferred into the embryo. A modified embryo is implanted inside the foster female and at the end of the duration of pregnancy, a healthy baby birth by the foster mother (Singhal & Kansara., 2017).

Advantages:

  • At the early stage of cell, transgenes are tested by this method.
  • This method is very effective in homologous recombination in the contrast to other cells of the animal.
  • To identify precisely alterations (Wakchaure. R et al., 2015).


3.    Retrovirus Mediated Gene Transfer:

A virus that carries the genetic material in the RNA form is called a retrovirus. To increase the gene expression probability, gene transfer is mediated by a vector, usually or a plasmid or a virus. Commonly retrovirus is used to transfer the foreign genes into the host cell, because of their capability to infect cells of the host. Transgene transmission is feasible if the retrovirus fused into the germ cells (Datta, S., et al, 2018).

Advantages:

  • This method is technically simple.
  • Infectious retroviruses are not capable to infect cells of humans.
  • Manipulation eases for the addition of the therapeutic genetic material.
  • Capability to steadily incorporate into the targeted cell
  • Comparatively easy method for recombinant virus preparation (Wakchaure. R et al., 2015).


By: Sadia Israr


References:

1.    Datta, S., Mishra, S., Taraphder, S., Roy, M., & Das, U. (2018). Applications of transgenic animal production for enhancement of human welfare: A critical review. International Journal of Livestock Research, 8(2), 32-42.

2.     Mohammed, F., Shibbiru, T., Mengistu, A., Tadesse, F. (2016). Transgenic Animal Technology: Technique and Its Application to Improve Animal Productivity. Advances in Life Science and Technology, Vol.48.

3.     Rajoriya. R., Rajoriya. S., and Kumar. N. (2013). Transgenic animals: prospects for improving livestock productivity. J.Bio.Innov 2(5), 240-259.

4.     Singhal. M, and Kansara. N. (2017). Transgenic animals: production and application. International journal of pharmaceutical sciences and research. Vol.1 (9): 12-22

5.     Wakchaure. R, Ganguly. S, Praveen. K, Para. A. P.  (2015). Transgenic Animals: A Review on its Various Dimensions and Applications in Animal Biotechnology. International Journal of Emerging Technology and Advanced Engineering. Vol 5.


 

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