Download Transgenic Organisms

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T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology..
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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..
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Transgenic 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..
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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..
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Transfection & Molecular 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..
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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.
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T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology..
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From
T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology..
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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.
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T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology..
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culture of ES cells with preparation of vector DNA
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T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology..
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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..
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From
T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology..
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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..
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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..
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Transgenic Chickens
grow 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..
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end
From
T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology..
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