transgenic animals - intro methods examples

1. By –
Miss. Asmita Prabhudatta Sagar
B.Sc. Biotechnology III

2.  Introduction
 Methodology to produce transgenic animals :
1.Retrovial Vector Method.
2.DNA microinjection method .
3.Engineered Embryonic Stem Cell Method.
 Examples
 Applications
Disadvantages
Summary
References

3.  In 1974 Rudolf Jaenisch created
a transgenic mouse by introducing foreign
DNA into its embryo, making it the world’s first
transgenic animal.
 What is a transgenic animal ?
An animal whose genetic composition has been altered by the addition of
foreign (exogenous) DNA is said to be transgenic .
The DNA that is introduced is called a transgene
and the overall process is called transgenic technology or transgenesis
 He injected retrovirus DNA into early mouse
embryos and showed that leukemia DNA
sequences had integrated into the
mouse genome and also to its offspring.

4. Strategy used for this :
 A cloned gene is injected into the nucleus of a fertilized egg.
 The inoculated fertilized eggs are implanted into a
receptive female.
 Some of the offspring derived from the implanted eggs
carry the cloned gene in all their cells.
 Animals with the cloned gene integrated in their germ line cells
are bred to establish new genetic lines.

5. For transgenesis,DNA can be introduced into mice by
(1) retroviral vectors that infect the cells of an early
stage embryo prior to implantation into a receptive
female
(2) microinjection into the enlarged sperm nucleus
(male pronucleus) of a fertilized egg, or
(3) introduction of genetically engineered embryonic
stem cells into an early-stage developing embryo
before implantation into a receptive female.

7. i. Vectors derived from these viruses can transfer only small
pieces (~8 kilobases [kb]).
ii. The genome of the retroviral strain can be integrated into the
same nucleus as the transgene.
•Drawbacks:
•Advantage:
i. An effective means of integrating the transgene
into the genome of a recipient cell.

9. •Advantages:
i. Most common technique for transferring the transgene.
ii. Most reliable technique for transgenesis.
iii. Process is inexpensive.
•Drawbacks:
i. Requires the coordination of a number of experimental steps and
highly trained practitioner.
ii. Often multiple copies of the injected DNA are incorporated at
one site which disrupts the normal physiology of the animal.
Iii. Only 5% of the inoculated eggs to develop into live transgenic
animals.

11. •Advantages:
•Drawbacks:
i. Reduction in the cost of producing a transgenic animal.
ii. Randomness of integration is avoided.
iii. ES cells enable the researcher to place new genes in advantageous
places in the genome or to remove deleterious genes.
i. Requires longer time .
ii.
Requires germline-competent ES cell lines.
iii. Difficulties associated with the production, characterization
and maintenance of pluripotent ES cell lines.

12. Glo fish :
GloFish is a type of transgenic
zebrafish (Danio rerio) that
have been obtained via
insertion of a green
fluorescent protein (GFP)
gene.
Super fish
Growth hormone gene inserted
into fertilized egg. The
transgenic salmon were larger
and grew faster than the
nontransgenic controls.

13. Alzheimer’s mouse
“ ANDI” was the first transgenic
monkey, born in 2000.ANDI
proves that transgenic primates
can be created and can express
a foreign gene delivered into
their genome.
ANDI Monkey
In the brain of Alzheimer’s
patients, dead nerve cells are
entangled in a protein called
amyloid.Mouse made by
introducing amyloid precursor
gene into fertilized egg of mice.

14. Industrial importance –
 Toxicity sensitive transgenic animals to test chemicals.
 Spider silk in milk of goat.
Medical importance –
 Disease model.
 Xenotransplantation.
Agriculture importance –
 Disease resistant animals.
 For improving quality & quantity of milk, meat, eggs & wool production.

15. × Ethical issues.
× They has the potential to harm certain native species of animals
or plants.
× It can also potentially affect the environment, thus altering the
living conditions of many species.
× Introduction of transgenic may also affect the direction of
evolution and eventually decrease the gene pool.
× Transgenic animals are costly to produce and they have high
value.
× The production of transgenic animal may lead to food-safety
problems like allergies or toxicities.

16.  An animal whose genetic composition has been altered by the
addition of foreign (exogenous) DNA is said to be transgenic .
 There are 3 main methods of transgenesis :
1.Retrovial Vector Method.
2.DNA microinjection method .
3.Engineered Embryonic Stem Cell Method
 Many transgenic animals have been successfully created for a
variety of purposes, and the prospects are enormous.
 It holds great potential in many fields including agriculture,
medicine and industry.
 There are certain disadvantages regarding this technique.

17. I. Molecular biotechnology : principles and applications of
recombinant DNA / Bernard R. Glick, Jack J. Pasternak, and
Cheryl L. Patten. — 4th ed.
II. Satyanarayana U, Biotechnology (2010), 1st edition, Books
and allied (P) Ltd, Kolkata
III. https://en.wikipedia.org/wiki/Genetically_modified_organis
m#Transgenic_animals
IV. http://dsc.discovery.com/technology/tech-10/genetic-
engineering/10-transgenic-animals-03.html
V. www.biomedcentral.com/1471-2407/12/209

18. Thank You ..