Applications of transgenic animals
Applications of transgenic animals
The animal production industry is gradually reaching towards revolution due to the development of the genetic map, knowledge of the expression of genes and techniques for large propagation. Transgenic animals are used as tools in research and for the production of recombinant proteins, The main applications of transgenic animals are described as follows:
Studying gene function:
The transgenic expression is not only used to breed animals which have specific traits but also to breed animals that are lacking specific genes, This technique is called as knockout or gene targeting. Transgenic technology was perfected using mice in the early 1980s. Knockout mice which lack functional forms of specific genes are produced which provide information about the function of the knocked-out gene. This technique allows scientists to target specific genes for inactivation and mutagenesis.
Molecular pharming or pharmaceutical production:
Transgenic sheep, goat and cattle are bring used as ‘bioreactors’ to produce important human proteins in milk. Milk is produced in large quantities and can be collected without harm to the animals. Livestock is used to produce medicines and nutraceuticals. Transgenic animals mainly produce the desired drug at high levels without endangering their own health and pass its the drug at high levels to its offspring. Proteins commonly produced from transgenic animal includes the blood-clotting protein Factor IX, lactoferrin, human protein C, alpha-1-antitrypsin etc. Drugs developed in transgenic animals are listed in Table 19.2. Human drugs purified from animal milk or blood are likely to require exceptional levels of safety testing before animal and human health concerns are addressed to the satisfaction of consumers.
Biomedical research model: Transgenic animals can be created which simulate human diseases in which defective genes play a major role. Human mutant genes are inserted into mice and other animals, causing them to suffer from human diseases. Such transgenic animals are used as a disease model for investigations into the development of the particular disease and medicine to prevent it. These animal models facilitate the identification of chemically induced mutations, gene expression and are instrumental in identifying signal transduction pathways and hormonal factors that modulate the activity of genes. Transgenic animals are used as a model for diseases such as cancer, autoimmune diseases, diabetes, cardiovascular, Alzheimer’s disease neurological diseases, AIDS, cystic fibrosis, hypercholesterolemia etc Transgenics are also important research tools for studying environmental pollutants bone marrow germinal cell mutations and target organ Susceptibility.
The mouse is the most widely used animal model in transgenic research. The genetic makeup of the mouse resembles that of humans, rapid reproduction rates and relative ease of genetic manipulation are the important characteristics for animal model mainly observe in mice. Rat sheep. cow, goat and pigs are commonly used as research models and for production of protein-based pharmaceuticals.
Transgenic animals in agriculture: Transgenic pigs bearings a human metallothionein promoter porcine growth-hormone gene construct showed significant improvements in economically important traits such as growth rate, feed conversion and body fat/muscle ratio. Transgenic sheep carrying a keratin-IGFI construct showed that expression in the skin and the amount of clear fleece is about 6 to 7% greater in transgenic than in non-transgenic animals.
Dairy production is an attractive field for targeted genetic modification, It is possible to produce milk with a modified lipid composition by modulating the enzymes involved in lipid metabolism or to increase curd and cheese production by enhancing expression of the casein gene family in the mammary gland. Transgenic applications used in animals to enhance disease resistance include the transfer of major histocompatibility complex genes, T-cell receptor genes and immunoglobulin genes. Transgenic constructs bearing the immunoglobulin A (LA) gene have successfully introduced into pigs, sheep and mice in an attempt to increase resistance against infections. Transgenic animals are playing a major role in the drug development process and the potential benefits to human and animal health.