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Methods of creation of transgenic animals - Coggle Diagram
Methods of creation of transgenic animals
Embryonic stem cell-mediated gene transfer
prior insertion of the desired DNA sequence by homologous recombination into an in vitro culture of embryonic stem (ES) cells
have the potential to differentiate into any type of cell (somatic and germ cells)
cells are then incorporated into an embryo at the blastocyst stage of development
The result is a chimeric animal
ES cell-mediated gene transfer is the method of choice for gene inactivation, the so-called knock-out method
This technique is of particular importance for the study of the genetic control of developmental processes
It has the advantage of allowing precise targeting of defined mutations in the gene via homologous recombination.
DNA microinjection
construct (a single gene or a combination of genes) from another member of the same species or from a different species.
effective in mammals (Gordon and Ruddle, 1981).
DNA may lead to the over- or under-expression of certain genes or to the expression of genes entirely new to the animal species.
insertion of DNA is, however, a random process.
introduced gene will not insert itself into a site on the host DNA that will permit its expression.
The manipulated fertilized ovum is transferred into the oviduct of a recipient female.
foster mother that has been induced to act as a recipient by mating with a vasectomized male.
Retrovirus
mediated gene
transfer
To increase the probability of expression
gene transfer is mediated by means of a carrier or vector
Offspring derived from this method are chimeric
Retroviruses are commonly used as vectors to transfer genetic material into the cell
not all cells carry the retrovirus
Transmission of the transgene is possible only if the retrovirus integrates into some of the germ cells.
For any of these techniques the success rate in terms of live birth of animals containing the transgene is extremely low
For-example
Transgenic fish
Transgenic chicken
Transgenic mice
Transgenic rabbits
Transgenic goats
Transgenic sheep
Transgenic pigs
Transgenic cows
Transgenic dogs