Transgenic animals are animals that have been genetically modified to carry foreign genes inserted into their genome. This document discusses the production of transgenic animals, their applications in medicine, agriculture and industry, as well as issues related to their use. Transgenic animals are produced using techniques like pronuclear microinjection, retrovirus-mediated gene transfer, and embryonic stem cell-mediated gene transfer. They can be used for research, increasing agricultural yields, producing pharmaceuticals, and testing chemicals. However, there are also biosafety, ethical and environmental issues to consider with transgenic animals. With proper research and regulation, transgenic animals could help address problems that currently lack solutions.

1. MBB611/607 MEDICAL
BIOTECHNOLOGY/APPLIED
BIOTECHNOLOGY
ASSIGNMENTAND SEMINARS
TOPIC2: TRANSGENIC ANIMALS
STUDENT NAME: BARAKA L NGINGO
MSC ONE HEALTH MOLECULAR BIOLOGY
REG NUMBER: MOH/D/2018/0041
INSTRUCTOR: PROF MACHANGU R

2. Outline
Introduction
Advantages and disadvantages
Examples of transgenic animals
Methods for production of transgenic animals
Application of transgenic animals
Issues related to transgenic animals
Conclusion

3. Introduction
Transgenic animals are one that carries a foreign gene that has
been purposely inserted into its genome by transgenesis.
The foreign gene is constructed using recombinant DNA
methodology
Foreign genes are inserted into the germ line not in somatic cells of
the animal.
Fishes, livestock and other animals with altered genetic profiles
which are useful to mankind have been developed.

4. History of transgenic animals
1970’s, first transgenic mice via viral infection, but not germline
transmission
1980’s, first transgenic mice via microinjection. The most popular
technique
1985, First transgenic rabbits, sheep, pigs and cattle
1980-1990, commercial transgenic services, via transgenic facility
1990’s, transgenic farm animal campanies as bioreactors and organ
donors

5. Examples of transgenic animals, Source: Google images

6. Advantages and disadvantages of
transgenic animals
Advantages:
•Increased growth rate.
•Improved disease resistance.
•Increased muscle mass.
•Improved nutritional quality.
•Improved wool quality.
Disadvantages:
• Inserted gene has multiple
functions.
• Breeding problems.
• Sometimes leads to
mutagenesis and functional
disorders.
• Low survival rate of transgenic
animals.

7. Production of transgenic animals
Step 1- construction of a transgene.
•Transgene made of three parts- Selection marker, Promoter, Gene to be expressed
and Termination sequence
Step 2- Introduction of foreign gene into the animal.
•There are many methods for gene transfer, three basic methods used are:
i. Pronuclear DNA microinjection
ii. Retrovirus-mediated gene transfer
iii. Embryonic stem cell-mediated gene transfer

8. Step 3 – Screening for transgenic positives.
•Transgenic progenies are screened by PCR to examine the site of
incorporation of the gene, use of selection marker and other DNA
techniques.
•Some transgenes may not be expressed if integrated into a
transcriptionally inactive site.
Step 4 – Further animal breeding is done to obtain maximal expression.
•Heterozygous offspring's homozygous strains are mated to form
homozygous offspring.

9. Method for gene transfer:
1. Pronuclear DNA Microinjection
A female animal is super-ovulated, eggs are collected and fertilized
in vitro.
The transgene containing solution is injected into the male
pronucleus.
Eggs with the transgenes are kept overnight in an incubator to
develop to a specific embryonic phase.
The eggs are then implanted into the uterus of a pseudo pregnant
female.
The mouse was the first animal to undergo successful gene transfer
using DNA microinjection.

10. Source: Google images

11. Retrovirus-Mediated Gene Transfer
A retrovirus is a virus that carries its genetic material in the form of
RNA rather than DNA.
This involves transfer genetic material by retrovirus into the host
cell (4-16 cell stage embryos) forming chimera, an organism with
tissues or parts of diverse genetic composition.
Chimeras are inbred for many generations until homozygous
transgenic offspring are born
The method was successfully used in 1974, a simian virus was
inserted into mice embryos, resulting in mice carrying this DNA.

12. Source: slideshare and google images

13. Embryonic Stem Cell-Mediated Gene
Transfer
Transgenic animals can be created by manipulating embryonic
stem cells obtained from the inner cell mass of a blastocyst.
Transgene is incorporated into the ES cell by: microinjection,
retro virus and electroporation
Transgenic stem cells are grown in vitro and then inserted into a
blastocyst and implanted into a host’s uterus to grow normally.
This method allows testing for transgenes at the cell stage.

14. Source: Google images

15. Applications of transgenic animals
Are used for research and other studies such as gene
functions, disease model etc
Are used to amplify desired characteristics or products
which are beneficial to mankind.
Are used as food
Generally they are used in medicine, agriculture, and
industries as explained below

16. In medicine
i. Xenotransplantation
Transgenic pigs may provide the transplant organs needed to
alleviate the shortfall.
ii. Nutritional supplements and pharmaceuticals
Products such as insulin, growth hormone, and blood anti-clotting
factors can be obtained from the milk of transgenic cows, sheep, or
goats.

17. In medicine contd.
iii. Human gene therapy
Involves adding a normal copy of a gene (transgene) to the genome
of a person carrying defective copies of the gene. Transgenic animals
could play a role of making gene copies.
The potential for treatments for the 5,000 named genetic diseases
is huge and transgenic animals could play a role.
iv. Disease models

18. In agriculture
i. Increasing yields
Transgenesis made it possible to develop animals with traits like
increased milk production, high growth rate. Offering farmer an easy
way to increase yields.
ii. Quality
Transgenic cows exist that produce more milk or milk with less lactose
or cholesterol, pigs and cattle that have more meat on them, and sheep
that grow more wool.
iii. Disease resistance
iv. Biocontrol of plant diseases

19. In Industries
Toxicity-sensitive transgenic animals have been produced
for chemical safety testing.
Animals can be engineered to produce a wide variety of
proteins, which in turn can produce enzymes that can speed
up industrial chemical reactions.
 Manufacture Spider silk in milk of goat.
Used to test vaccines and drugs
Used as bioreactors

20. Issues related to transgenic animals
There may be biosafety issues or health risks associated
with transgenics.
There is ethical issues related to production of transgenic
animals
There may be long term effects on the environment when
transgenic animals are released into the field (loss of
biodiversity)

21. Conclusion
With proper research and careful considering bioethics
and biosafety, use the transgenic animals can go a long way
in solving several problems for which science doesn't have a
solution till now.
Example: emerging and re-emerging diseases and
antimicrobial resistance.
Transgenic animals can me used in studying pathogenesis,
diagnosis, treatment and even preventions

22. References
1. O. G. Maksimenko, A.V. Deykin, Yu. M. Khodarovich, and P. G.
Georgiev. Use of Transgenic Animals in Biotechnology: Prospects and
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by transgenic animals. Comp Immunol Microbiol Infect Dis. 2009
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19.