Transgenic animals are organisms whose genomes have been modified by the insertion of a foreign gene. This process alters their DNA to enhance specific genetic traits. The technique is widely used to improve the genetic characteristics of target animals.
In earlier times, genetic improvements were achieved through selective breeding, where animals with desired traits were mated to produce offspring with enhanced characteristics. However, this method was time-consuming and costly. The advent of recombinant DNA technology has revolutionized this process, enabling precise and efficient genetic modifications.
Transgenesis refers to the process of introducing a foreign gene, known as a transgene, into the genome of an animal. The organism with the altered genome is called a transgenic animal. These genetic modifications are heritable and can be passed on to subsequent generations.
Transgenic animals are genetically engineered organisms, often referred to as genetically modified organisms (GMOs). The first genetically modified organism was successfully created in 1980, marking a significant milestone in biotechnology.
Below, we explore the detailed process, significance, and diverse applications of transgenic animals.
Below are the following methods of the transgenic animals-
Physical Transfection
Chemical Transfection
Retrovirus-Mediated Gene Transfer
Viral Vectors
Bactofection
Following are the examples of transgenic animals:
Transgenic animals (most common mice) have gradually inserted a foreign gene into their genome. The microinjection of DNA usually creates such animals into the pronuclei of a fertilised egg later implanted into the oviduct of a pseudopregnant surrogate mother.
This method involves the direct microinjection of a chosen gene construct (a single gene or a combination of genes) from another member of the same species or a different species into the pronucleus of a fertilised ovum. It is one of the first methods proved to be effective in mammals (Gordon and Ruddle, 1981). The introduced DNA may lead to the over-or under-expression of specific genes or the expression of genes entirely new to the animal species.
Stem cells are undifferentiated cells that can differentiate into any type of cell (somatic and germ cells) and, therefore, give rise to a complete organism. These cells are then combined into an embryo at the blastocyst growth stage. The result is a chimeric animal.
This method increases the possibility of expression; gene transfer is mediated utilising a carrier or vector, generally a virus or a plasmid. Retroviruses are typically used as vectors to transfer genetic material into the cell, taking advantage of their ability to infect host cells in this way. Offspring emanated from this process are chimeric, i.e., not all cells carry the retrovirus.