Transgenic Animals: Definition, Methods, Examples & Application

One of the most important scientific advances of our time is the possibility of being able to clone animals. Medical and biotechnological applications are numerous because cloning has made it possible to eradicate a large number of diseases. Still, what is a genetically modified animal? What are the advantages and disadvantages of this technique?

In this new article on ybstudy.com, we discuss what are Transgenic Animals – Definitions, Examples, and Characteristics we will explain in detail what genetically modified animals are, in addition, we will present you with examples of famous transgenic animals.

What is transgenesis?

Transgenesis is the process through which genetic information (DNA or RNA) is transferred from one organism to another, allowing the organism to convert new genes and all its descendants into transgenic organisms. Complete genetic material is never transferred, just one or more previously selected, extracted, and isolated genes are transferred.

Definition of Transgenic Animals

Transgenic animals are animals that have been genetically modified. As we know all living things and all animals can be genetically manipulated. There is a bibliography in which we can see that animals such as sheep, goats, cows, rabbits, rats, rats, fish, insects, parasites, and even humans have been genetically manipulated. But initially, the mouse was used, and with the mouse, all the tests conducted were crowned with success.

The use of mice for genetic manipulation has been particularly widespread for several reasons:

1. You can easily add new genetic information inside your cells.
2. These genes have a certain ease to pass on to her offspring.
3. The mouse has a short life cycle and many litters.
4. It is a small animal that is easy to handle and is rarely stressed if you pay attention to its physical and mental health.
5. Its genome is similar to humans.

Methods of Transgenesis

Several techniques allow the production of transgenic animals:

1. Transgenesis by microinjection of zygotes

• Using this technique, first of all, by using hormonal treatment, a female is induced to super-ovulate. Then, the fertilization is carried out which can be carried out in vitro or in vivo.
• Then we will extract the fertilized eggs and isolate them. Here will end the first part of the technique.
• Secondly, the zygotes (cells resulting from the union of an ovum and a spermatozoon naturally or through in vitro or in vivo fertilization) are injected by micro-injection with a solution that contains the DNA we want to add to the genome.
• Then, the modified zygotes are reintroduced into the maternal uterus so that gestation can be completed naturally.
• Finally, once the babies are born, grown-up, and weaned, we check whether the transgene (external DNA) has been assimilated into its genome.

2. Transgenesis by manipulation of embryonic cells

• In this technique, instead of using zygotes, the transgene is introduced into maternal cells. These cells are taken from the developing blastula (phase of embryonic development characterized by a single layer of cells) and are then introduced into a solution that prevents the cells from differentiating and being cells of the mothers.
• The foreign DNA is introduced into the blastula and reintroduced into the maternal uterus.
• The offspring obtained with these techniques is a chimera, which means that some cells in their body will express this gene and others will not.
• For example, the same name for a hybrid between a sheep and a goat is a chimera between a sheep and a goat, the animal resulting from this hybridization has parts of the body covered with hair and other parts covered with wool.
• Using the technique that we have just presented to you, we will obtain hybrids and/or chimeras in which the individuals will have the transgene in their germline, that is to say, that they will have the transgene in their ova and spermatozoa.

3, Transgenesis by the transformation of somatic cells and transfer of nuclei or cloning

• Cloning involves extracting embryonic cells from a blastula, cultivating them in vitro, and then introducing them inside an oocyte (female germ cells) from which the nucleus has been previously extracted.
• In this way, they merge so that the oocyte is transformed into an ovum having within its nucleus the genetic material of the original embryonic cell, which allows it to continue its development as a zygote.

GMO animals: Examples Of Transgenic Animals

• Frogs: in 1952 the first cloning in history was carried out. This cloning is what served as the basis for cloning Dolly.
• The Dolly Sheep: this cloning is famous because it is the first animal cloned by the technique of cell nucleus transfer from an adult cell. This case is not famous because it is about the first cloned animal. After all, as we have just seen it the first cloned animal was a frog. Dolly was cloned in 1996.
• Noto and Kaga cows: they have been cloned in Japan several thousand times. By cloning them thousands of times scientists were looking for a way to improve the quality and quantity of meat for human consumption.
• The Mira goat: this goat was cloned in 1998, it was the forerunner of what is called the engineered cattle which was able to produce in its body useful drugs for humans.
• The Ombretta mouflon: the first animal cloned to save an endangered species
• The copycat cat: in 2001, the company Genetic Saving & Clone, cloned a domestic cat for commercial purposes.

Advantages and disadvantages of transgenesis

When discussing controversial subjects such as transgenesis and transgenic animals, it is essential to weigh their advantages and benefits, as well as their possible risks. In this way, we will be able to maintain a more rational and informed perspective on such an important topic.

Advantages/Benefits ofTransgenesiss

• Various studies and research carried out to study and improve transgenesis, these studies have considerably increased knowledge about the genetic configuration of many species.
• Better knowledge of the genome is helping to advance the development of new treatments for many diseases that affect animals and humans, such as cancer.
• The production of drugs has also been able to evolve thanks to experiments with transgenic animals. Much of the latest generation of drugs has been produced thanks to advances in genetic manipulation.
• Transgenesis could revolutionize the current system of organ and tissue transplantation. Currently, there is a long wait for patients in need of a donation. It also promotes the production of stem cells for regenerative cell therapy.
• Cloning techniques can also make the creation of a gene bank viable. This would prevent the disappearance of many species from our ecosystems due to human activities.

Disadvantages and Risks of Transgenic Animals

• Transgenic animals may be more vulnerable to allergic reactions, among other things, through the expression of certain proteins that were not part of the original genetic information.
• It is not yet possible to predict with certainty the exact location of the new gene in the genome of the transgenic organism. Therefore, it is not always easy to predict the result of passing genes from one individual to another.
• Populations of transgenic animals should be strictly controlled so as not to threaten native species in each ecosystem.
• The use of living things for these experiences raises ethical questions. We, therefore, debate the limits of science and human action, on other forms of life and nature.

Application of transgenic animals.

1. Transgenic animals have great benefits to mankind.
2. Due to transgenesis, there is an improvement in the quality and quantity of milk, meat, eggs, etc.
3. Study of diseases: Many transgenic animals help us to understand how genes contribute to the development of disease.
4. With the help of these animals which act as a model for human diseases like cancer, cystic fibrosis, rheumatoid arthritis, Alzheimer’s disease, etc. new methods of their treatment are possible.
5. 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
6. Bioreactors: By transgenesis, the animals are genetically modified in such a way that they act as bioreactors.
7. Such transgenic animals are useful to produce d-1-antitrypsin which is used to treat emphysema.
8. Similarly, phenylketonuria (PKU) is being treated. In 1997 the first transgenic cow was produced called ‘Rosie.
9. This cow produced human protein-enriched milk (2-4 gms/liter).
10. This is a nutritionally more balanced milk product than natural cow milk.
11. Chemical safety testing: Transgenic animals with foreign genes are produced consequently the transgenic animals become more sensitive to toxic chemicals.
12. These animals are exposed to toxic chemicals, and toxicity testing in such animals gives fast results.