Question

a) Why are transgenic animals so called?
b) Explain the role of transgenic animals in: (i) Vaccine safety and (ii) Biological products with the help of an example in each.

Answer 1

Transgenic basically means that one or more DNA sequences from ‘‘other’’ species have been introduced by artificial means. GMOs (genetically modified organisms) are organisms whose genetic material has been changed by genetic modification techniques. The production of transgenic livestock has the opportunity to significantly improve human health, enhance nutrition, protect the environment, increase animal welfare and decrease livestock diseases.

Complete answer:
a) Transgenic animals are those whose genomes have been altered to include a foreign gene. Genes can be transferred within the same species, or across different species. The ‘transgenic’ is so called, because it specifically refers to the genetic modification across species. Creating a genetically modified organism is a multi-step process. The gene of interest is first isolated and then they are transferred to the host organism in such a way that it combines with the genomic element of the host so that it can multiply in the host body to produce its effect. The need to modify has the intention of improving economically important traits such as growth rate, quality of meat, milk composition, disease resistance, and survival. The most common transgenic animal is rat, over $95\%$ of the transgenic animals are rats. ELISA and PCR amplification are the two most popular methods for detecting the existence of a gene or transgene.
b) Transgenic animals are specifically designed to allow the study of how genes are regulated and how they affect the normal functions of the body and its development. Transgenic animals play a role in different ways.
(i) Vaccine Safety: Transgenic animals are created that carry genes such that it makes them a lot more sensitive to hepatotoxic substances than non-transgenic animals. They are then exposed to the hepatotoxic substances and the effects are studied. For ex. Until polio vaccines were used on humans, transgenic mice were used to test their efficacy.
(ii) Biological Products: The insertion of a gene that codes for a specific product will result in transgenic animals that generate useful biological products. It helps in enhancing the nutritional quality of food. Say, for ex. the first transgenic cow, ‘Rosie’, in $1997$ was genetically modified to produce human protein $\left( {\alpha - 1{\text{ }}antitrypsin} \right)$ enriched milk $\left( {2.4gm/L} \right)$ that is used in treating emphysema. The milk contained α-lactalbumin and was nutritionally a more balanced milk for human babies than natural cow milk.

Transgenic animals are genetically modified organisms and are used to produce many medicines and vaccines that help treat or prevent diseases. The other benefits of GM include more nutritious food, disease resistant varieties, etc.

Note:
Similarly, genetic modification techniques are applied in plants to produce crops that are tolerant to stress, helps increase in the mineral usage by plants, making it disease resistant, enhancing its nutritional value and helps reducing the post harvesting losses. A GM crop also reduces the reliance on chemical pesticides. A most common example of GM plant is Bt cotton, is a pest resistant plant produced by genetic modification in the plant. Bt toxin gene from Bacillus thuringiensis was isolated and introduced in plants like cotton to decrease use of pesticides. Cry genes, cryIAc and cryIIAb control cotton bollworms and cryIAb controls corn borer.