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CLONING What is Cloning ?

Cloning means the production of exact genetic replicas of an individual. In other words, a clone cannot be considered as offspring, but simply the copy of a given individual. Thus cloning is a bio-technique for copying individuals by manipulations at cellular level.

There are two kinds of cloning: Gene cloning at a molecular level and Cloning of an individual.

Gene cloning is done in three stages: The targetted gene in a cell is first isolated The isolated gene is introduced in different living organisms It is ensured, that the recipient accepts the donor gene and inherits it's properties.

While cloning of an individual is slightly of different kind, as we know that the cell of any animal is diploid in character, and bears the characters of both male and female individuals. In organism cloning, the nucleus of the haploid cell ova is replaced by the nucleus of diploid cell. This is then made to undergo the normal process of growth within the mother's uterus. Thus mother delivers a clone of itself at the end of pregnency. Thus organism cloning generally involves transplantation of a nucleus from the body cells or embryonic cells into a enucleated unfertilized egg in the lab, thereby bypassing the usual process of fertilization of egg by sperm.

History of Cloning

In 1955, Robert Briggs and Tom King of Cancer Research Institute in Philadelphia, USA, for the first time carried out nuclear transplantation experiments on embryonic cells of frog. This led Briggs and King to conclude that as the development advances, cell nucleus becomes irreversibly differentiated.

In 1960, J.B. Gurdon, an embryologist at Oxford University, U.K found development of normal embryo following transplantation of differentiated intestinal nuclei from tadpole into the nucleus - free unfertilized egg of different amphibian species. Gurdon concluded that during development cells differentiate irreversibly

The role intranuclear interaction between cytoplasm and nucleus was clearly demonstrated by Harris (1965) through protoplast technology.

Cloning of Dolly Sheep:

The birth of Dolly, a clone of an adult sheep was a turning point in the realm of biotechnology. In 1995, Dr. Ian Wilmut and his team of researchers at Roslin Institute in Edinberg (Scotland) took udder cells from a 6 year old female sheep-a Fin Dorset Ewe, and placed it in a special solution that controlled it's division or cell cycle. The cell was deprived of certain nutrients. At the same time, an unfertilized egg was obtained from another adult sheep. It's nicleus was carefully removed leaving the cytoplasm intact. The nucleus of udder cell was taken out and transferred into the enucleated egg. The actual fusion was encouraged by a small electric nudge, and the cells were then allowed to grow and divide in culture dish. Subsequently the transplanted nucleus became fuctional according to the new surroundings in which it has been artificially placed. This variable combination underwent cleavage like that of a normal zygote. The resulting embryo was then transplanted into the uterus of the third adult sheep (surrogate mother) for its further development. Subsequently, a normal healthy little lamb – Dolly was born on 1996. The new born sheep was genetically similar to her 'clone mother' from which the nuclear DNA was taken for transplantation. However, it does not have any genetic similarity with the sheep from which the egg was taken or 'surrogate mother', because they did not contribute any nuclear DNA in the process. Another unique feature of Wilmut's experiment is that a carbon copy of the adult sheep was produced without involvement of the male genetic material, indicating thereby that sperms are not necessary for the progeny. The natural reproduction process can thus be short circuited by the cloning technique.

Simian Cloning

The simian cloning was done through in-vitro fertilization by mixing eggs from a single female with sperms in a petri dish. Once embryo developed, Dr. Wolf and his colleagues divided it into eight egg cells and produced genetically two monkeys. Cloning of monkeys is a whole new ballgame because they are closely related to human cloning. The two monkeys were born in August 1996.

Future Scenario

The scientist who created Dolly lamb said, they hoped to make a genetically manipulated 'Clone' that contained human genes. Cloning is a natural out growth of their research into animal breeding and the production of medicines from animal's blood and milk. Dr. Steven Stice and James of Advance Cell Technology Corporation, Texas (USA) and developed a technique for clonning genetically customized calves that will be able to produce medicines for humans in their milk. The first cloned calves – George and Charlie were born in January 1998, giving hope that cloned cows could become living pharmaceutical factories. Quite recently Will Eyestone, head of large Animal Technology with PPL Therapeutics, has shown off Mr. Jefferson, a cloned Holstein Bull Calf, at the large animal clinic of the Virginia-Maryland Regional College of Veterinary Medicine in Blacksburg, Va. Mr. Jefferson is named after Thomas Jefferson as he was born on Feb.16 President's Day.

Is Human Cloning Possible ?

So far scientist have not got to the stage of genetically altering human beings. A beginning has been made to identify many different kinds of genes under the Human Genome Project. Hence scientist all over the world are working on it, and have a target time of 2005 to identify every single gene in human genetic code. Once this is achieved, it would be possible to think of altering genes, and creating 'designer babies' with predetermined characteristics. Cloning of human was not been any new idea. In fact, in 1978, when test tube babies were in experimental stage, David M. Rorvik, an American Science journalist wrote a book (In His Image – The Cloning of a Man) in which he claimed to have witnessed the cloning of a human from a body cell from scientists who believe that it was a hoax. The Nobel Peace Prize recipient Prof. Joseph Rotblat, who has spent much of his life campaigning against nuclear weapons, has warned that developments in genetic engineering could pose a threat to mankind.

The debate on cloning has once again provided an opputunity where a scientific breakthrough has stepped beyond traditional legal, institutional and moral boundaries. American President has asked the administration to deny federal fundings for human embryo research, financed by federal dollars. The line of thinking of the American Government has been as to whether or not cloning of humans would be possible, but even a try in that direction is unethical. Dutch, German and French Governments have also announced several measures to control fuses abuses. Strict laws have been enacted in Great Britain, and a prior licence is required to conduct such tests. Unethical lines of arguments was taken up by the Vatican when it is contended that people have the right to be born 'in human way'. The European Parliament called for a global ban on cloning of humans, and also called for strict controls on the cloning of animals.

Human clones would have other problems too, mainly sociological ones. For instance, what is the relationship of Dolly to the Black Faced ewe that gave birth to her ? Is she a sister or daughter to the Finn Dorset ewe from which the udder cell came ? Besides the brain teasers, the most significant impact that human cloning would have ill effects on the male female relationships. Cloning would give the female a preferance in the natural scheme of things. For instance, a female could easily have her clone herself, but a man would still have to seek a woman's help to bear his clone. Whether this realization would bring any change in the male dominating societies, only time will tell. But whether humans will ever be cloned is a question “Do we need it ?”. Unless the latter is answered, the first will always remain a question of doubt. However, an international group of reproductive experts plans to launch a serious effort to clone humans to provide children to infertile couple.

Scientists have cloned sheep, beginning with 'Dolly' as well as mice and cows, but the idea of human cloning has been met with oppositions from both religious circles and scientific community.