From T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology.. EXIT

From T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology.. EXIT

The Transgenism is one of the thrust areas of Biotechnology /Genetic Engineering.

The methods of gene transfer lead to the production of Transgenic animals and plants.

These Transgenic organisms are called Genetically Modified Organisms.

From T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology.. EXIT

Transgenic animalTransgenic animal is one that carries a foreign gene that has been

deliberately inserted into its genome.

The foreign gene is constructed using recombinant DNA methodology.

In addition to a structural gene, the DNA usually includes other sequences to enable it

to be incorporated into the DNA of the host and

to be expressed correctly by the cells of the host.

From T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology.. EXIT

Transgenic sheep and goats have been produced that express foreign proteins in their milk. Transgenic chickens are now able to synthesize human proteins in the "white" of the eggs.

Transgenic mice have provided the tools for exploring many biological questions

Normal mice cannot be infected with polio virus.

They lack the cell-surface molecule that,

in humans, 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

and even develop paralysis and other pathological

changes characteristic of the disease in humans

From T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology.. EXIT

TransfectionTransfection & & Molecular farmingMolecular farming

The uptake of genes by the cells in animals is called transfection.

The transfected cells are used for a variety of purposes:

production of transgenic animals of commercial value.

production of chemicals and pharmaceutical drugs.

study of structure and function of genes.

The production of Transgenic animals of commercial value such as

livestock animals and fishes is called as Molecular farming.

From T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology.. EXIT

Gene transfer methods

In transfection, fertilized eggs / embryos or the cultured cells are employed.

The Embryonic Stem Cell Method

The Pronucleus Method

Transfer of genes to fertilized eggs or embryos.

The transfection of fertilized egg involves either the transfer of whole nuclei or whole

chromosomes; or their fragments or the DNA segments.

From T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology.. EXIT

From T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology.. EXIT

For the transfer of whole nuclei,

The cells are treated with cytochalasin B and enucleated.

The enucleated cells are incubated with the desired karyoplasts for the induction in presence of

Polyethylene Glycol (PEG).

For transfer of whole chromosomes,

metaphase cells are subjected to hypotonic lysis and individual chromosomes or fragments are isolated and then icubated with whole cells / eggs for transfection.

From T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology.. EXIT

culture of ES cells with preparation of vector DNA

From T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology.. EXIT

Microinjection of DNA segments:

In this the fertilized eggs are injected with DNA segments for integration.

DNA integrated eggs are then used for getting transgenic animals.

Transfer of genes to cultured cells:stem cells are undifferentiated precursor cells, the

genes can be delivered through retroviruses or

Directly by techniques of microinjection using particle

gun, electoporation or by the use of lysosomes.

From T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology.. EXIT

From T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology.. EXIT

Uses:1)Transgenic animals are more efficient than their

normal counterpart in feed assimilation.

2)They exhibit faster growth and hence achieve the marketable size sooner.

3)Meat quality is good.

4)They are resistant to certain diseases.

5)Serve as bioreactors for obtaining valuable recombinant proteins and pharmaceuticals from their milk or urine or blood.

From T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology.. EXIT

Transgenic pigs

have also been produced by fertilizing normal eggs

with sperm cells that have incorporated foreign DNA.

This procedure, called sperm-mediated gene transfer

(SMGT) may someday be able to produce transgenic

pigs that can serve as a source of transplanted organs

for humans

From T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology.. EXIT

Transgenic Chickensgrow faster and in large numbers can be grown in close quarters;

synthesize several grams of protein in the "white" of their eggs.

From T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology.. EXIT

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