Question

What are the two methods used to create transgenic animals?

Answer 1

Animals (most typically mice) that have had a foreign gene deliberately put into their genome are known as transgenic animals. Microinjection of DNA into the pronuclei of a fertilized egg, which is then implanted into the oviduct of a pseudopregnant surrogate mother, is the most popular method for producing such animals. The recipient animal gives birth to genetically modified offspring as a result of this. To generate a transgenic line, the progeny are bred with other transgenic children.

Complete answer :
DNA microinjection, embryonic stem cell-mediated gene transfer, and retrovirus-mediated gene transfer are the three main ways for creating transgenic animals.
1. DNA Microinjection : This procedure includes injecting a gene construct (a single gene or a mix of genes) into the pronucleus of a fertilized ovum directly from another member of the same species or from a different species. The imported DNA may cause over- or under-expression of specific genes, as well as the expression of genes that are completely new to the animal species.
2. Embryonic stem cell-mediated gene transfer : This procedure entails inserting the appropriate DNA sequence into an in vitro culture of embryonic stem (ES) cells by homologous recombination. Stem cells are undifferentiated cells with the ability to differentiate into any type of cell (including somatic and germ cells) and so give rise to an entire organism.
3. Retrovirus-mediated gene transfer : Gene transfer is mediated through a carrier or vector, usually a virus or plasmid, to improve the likelihood of expression. Because of their propensity to infect host cells, retroviruses are frequently used as vectors to transfer genetic material into cells. This approach produces chimeric offspring, meaning that not all cells have the retrovirus.

Note :
Transgenic animals are formed by adding a gene into an animal's genome on purpose. The gene that is intended to express favorable features during the recipient animal's growth and development is constructed using recombinant DNA technology. This is known as 'transgenesis,' and it entails the introduction of foreign genetic information into animals as well as the targeted inhibition of native gene expression.