Transgenic Animals - Methods, Examples and Applications

Transgenic animals are genetically modified organisms prepared by introducing foreign genes through gene transfer techniques such as microinjection or viral vectors. The transgenic animals can be defined as animals whose genomes have been altered to express specific characteristics or to secrete valuable proteins. Examples include therapeutic protein-producing transgenic sheep and disease research mice. In biology, the importance of transgenic animals has applications in medicine, agriculture, and biotechnology.

This Story also Contains

1. What are Transgenic Animals?
2. Principles of Transgenesis
3. Genetic Modification of Transgenic Animals
4. Applications of Transgenic Animals

What are Transgenic Animals?

Transgenic animals are organisms within which foreign genes have been purposely incorporated into their genome using recombinant DNA technology. This procedure is referred to as transgenesis, and with it, scientists can explore gene function and expression, produce pharmaceuticals, and enhance desirable characteristics in animals

The development of transgenic animals was initiated in the last century, and the creation of the first transgenic mouse took place in 1981. Since then, with the increase in applications of genetic engineering, many transgenic species have been developed for different purposes in both research and industry.

Transgenic animals are one of the important frontiers in modern science and agriculture. They are used in biomedical research to understand diseases, in the production of pharmaceuticals producing therapeutic proteins, and in agriculture to improve livestock and crop traits.

Methods for Creating Transgenic Animals

Some of the common methods of creating Transgenic animals are discussed below:

Bactofection

Bactofection: Bacteria are used to deliver genetic material into animal cells. In this method, bacteria are engineered to contain the desired gene, which is then transferred into the target animal's cells.

Viral Vectors

Viral vectors: The use of viruses to deliver new genes into the animal genome. Examples include retroviruses and adenoviruses engineered to transfer genetic material without causing disease.

Transfection

Transfection: the transfer of foreign DNA into animal cells by physical or chemical means.

• Physical Methods

Electroporation: An electric pulse makes transient pores in cell membranes DNA is forced into cells in this way.

Microinjection: DNA is directly injected into the nucleus of a cell using a fine needle.

• Chemical Methods

Lipofection: DNA is encapsulated in liposomes. The enveloped DNA is then more easily taken up by target cells.

Calcium phosphate transfection: Calcium phosphate is used to make a precipitate with DNA the cells then take up the DNA with the precipitate.

Mechanism of Gene Delivery via Viruses

The foreign gene in the viral vector is transferred into the host genome by infecting target cells and integrating the genetic material. The advantages of viral vectors in gene delivery include their high efficiency. Their major limitation is that viral vectors have posed several risks such as immune responses or insertional mutagenesis.

Examples and Applications

Viral vectors have been broadly used to generate transgenic animals both for research and therapeutic use.

Transfection of Transgenic Animals

The method involves the following process:

Physical Methods

• Electroporation

Type of Vector: Electrical pulse

Mechanism and Procedure: Electrical pulses make pores in cell membranes allowing the entry of DNA.

Advantages and Disadvantages: Very high efficiency but can lead to cell damage.

• Microinjection

Type of Vector: Direct microinjection

Mechanism and Procedure: DNA is directly injected into the nucleus of the cell.

Advantages and Disadvantages: Precise, but technically challenging and very labour-intensive.

Chemical Methods

The chemical methods are:

Lipofection

Type of Vector: Liposomes

Mechanism and Procedure: Liposomes encase DNA and help its entry into the cell.

Advantages and Disadvantages: Non-toxic however, it is less efficient than the viral one.

Calcium Phosphate Transfection

Type of Vector: Precipitation with calcium phosphate

Mechanism and Procedure: DNA precipitated with calcium phosphate is taken up by cells.

Advantages and Disadvantages: Simple and inexpensive, however, lower efficiency.

Principles of Transgenesis

Transgenesis: the insertion of foreign genes into an animal's genome. Several methods exist for accomplishing this, each with its advantages and challenges.

Comparison Table of Transgenic Techniques

Genetic Modification of Transgenic Animals

The genetic modification process includes:

Selection of Target Genes

Selection of the appropriate gene for a transgenesis experiment goes in line with prior information about gene function, expression, and probably the effect it might have on the host organism.

Vector Design and Construction

Vectors are tailored to accommodate the gene of choice. They will harbour some regulatory elements to ensure that gene expression within the host organism is accomplished as intended.

Applications of Transgenic Animals

Biomedical Research: Transgenic animals are extensively used to study diseases, mostly used in the development of their treatments and to study the functions of genes.

Pharmaceutical Production: Therapeutic proteins and other pharmaceuticals can be produced by transgenic animals, hence providing efficient, appropriate, and cheap ways to produce transgenic animals.

Agriculture: Improving livestock strains, for example, growth rate and disease resistance, which improve productivity and food security.

Disease Modeling: Transgenic animals can serve as model animals in the study of human diseases. They help researchers to get more insight into disease mechanisms as well as look for cures for some of the diseases.

Conservation Efforts: Transgenic animal techniques may be used to conserve endangered species by increasing genetic diversity and increasing their resilience.

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