A transgene:
An exogenous gene introduced into a living organism so that the organism will exhibit a new property and transmit that property to its offspring.
An exogenous gene introduced into a living organism so that the organism will exhibit a new property and transmit that property to its offspring.
Transgenic animals :
The animal that carries a deliberate modification/insert into its genome, the genetic makeup of an organism responsible for inherited characteristics.
The animal that carries a deliberate modification/insert into its genome, the genetic makeup of an organism responsible for inherited characteristics.
History of transgenic animal production
- 1966:Zygote microinjection technology established.
- 1970's: first transgenic mice via viral infection.
- 1977: mRNA and DNA transferred into Xenopus eggs.
- 1980's: first transgenic mice via microinjection (the most popular technique).
- 1985: first transgenic rabbits, sheep, pigs and cattle.
- 1990’s:transgenic farm animals used as bioreactors and organ donors.
- 1997: nuclear transfer using ES cells to drive transgenic sheep.
The majority and successful transgenic animals produced so far are mice, A few years later, it was followed by rabbits, pigs, sheep, and cattle fish, monkey, cat and cow.
Using recombinant DNA methodology
An animal contains a foreign gene (genes) introduced purposely by human intervention.
An example:
Normal mice cannot be infected with polio virus.
Mice lack the cell-surface molecule that found in humans, that serves as the receptor for the virus.
So normal mice cannot serve as an inexpensive, easily-manipulated model for studying the disease. However, transgenic mice expressing the human gene for the polio virus receptor
• can be infected by polio virus
• develop paralysis and other pathological changes characteristic of the disease in
humans.
Normal mice cannot be infected with polio virus.
Mice lack the cell-surface molecule that found in humans, that serves as the receptor for the virus.
So normal mice cannot serve as an inexpensive, easily-manipulated model for studying the disease. However, transgenic mice expressing the human gene for the polio virus receptor
• can be infected by polio virus
• develop paralysis and other pathological changes characteristic of the disease in
humans.
Why Transgenic Animals?
- Interest in transgenic animals originally fell into two broad areas:
- Molecular farming: using livestock to produce medicines, proteins and tissues for transplant to humans.
- Production efficiency of farm animals: Interest among researchers.
To date, there are three basic methods of
producing transgenic animals:
1-Embryonic stem cell-mediated gene transfer .
2- DNA microinjection.
3 -Retrovirus-mediated gene transfer.
producing transgenic animals:
1-Embryonic stem cell-mediated gene transfer .
2- DNA microinjection.
3 -Retrovirus-mediated gene transfer.
The benefits of these animals to human
welfare can be grouped into areas:
- Agriculture
- Medicine
- Industry
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