Cloning is making a copy of an organism. The animal clones produced have the same genetic makeup as that of the cloned organisms.
Natural evidence of cloning is found in bacteria, yeast, and other single-cell organisms that reproduce vegetatively.
In higher animals, evidence of cloning is not found. However, artificial animal cloning is possible. It was first successfully done by cloning Dolly, the sheep. It was started in 1979. However, successful cloning of Dolly could be done only in 1996.
Producing an animal of the same genetic makeup is called cloning. Clones can not be produced by the sexual reproductive process. Gene recombination occurs in sexual reproduction. Even the siblings are not clones. They differ from one another in their genetic makeup.
Animal cloning is somehow allowed in some countries, but human cloning despite different claims has not been done. Further, it is opposed on ethical grounds.
Identical twins are clones, as they develop from the single fertilized cell, the zygote.
The technology of animal cloning: Somatic Cell Nuclear Transfer
The technology used for animal cloning is SCNT( Somatic Cell Nuclear Transfer). It is the transfer of the somatic cell nucleus in the enucleated egg cell.
Animals can not be cultured in vitro. The production of the animal clone from a Somatic cell requires stimulation of the somatic cell. This stimulation is done through the somatic nucleus transfer in enucleated egg cells.
Steps involved in animal cloning
Somatic cells from the skin of animals.
An unfertilized egg is isolated from the surrogate mother.
The egg is enucleated, through irradiation or suction of the nucleus using a micropipette.
The enucleated cell is fused with the somatic cell/nucleus, and an electric pulse is used to fuse these cells. Microinjection can also be used for SCNT.
The fused cell is then allowed to divide and develop in the embryo.
This is then transferred to the surrogate mother.
The embryo develops into a clone of the organism.
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| Animal cloning ( SCNT) |
Uses of animal cloning
Animal cloning is used to
Improve cattle variety.
Increase milk and meat production.
Produce disease-free animals.
Studying gene expression.
Study gene therapy.
Improve food production.
Limitations of animal cloning
The clone produced is not a true copy of the animal.
As fur depends on the gene being expressed in an individual cell.
Aging occurs in the cells depending on telomer shrinking, cells cease to divide if the telomere shrinks excessively.
X- chromosome expression differs in somatic cells.
The success rate of animal cloning is very low. Dolly was produced after 276 unsuccessful attempts.
Disease-free animals are not produced through animal cloning as somatic cells become immunologically older.
Animals produced through genetic engineering are not allowed to be used as human food as their long-term effect on health is not known.
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