NUCLEAR TRANSFER AND ANIMAL CLONING

To produce genetically modified organisms Nuclear transfer is an ideal and widely used process.
Nuclear transfer was first reported in Xenopus in 1952, since then it is used in amphibians for experiments. The Nuclear Transfer involves replacement of nucleus with somatic cell nucleus.

Steps of Nuclear Transfer:

The first step involves the removal of the nucleus and the genetic material of donor cell is introduced into the enucleated oocyte.
Next step is activation of the renucleated oocyte (embryo). Naturally, it takes place by fertilization but in the laboratory, it is achieved by the electric pulse.
Finally, the embryo is cultured (in vitro) and transfer to the recipient animal.

Animal Cloning 

A process in which whole organism (animal) is reproduced from single cell isolated from the parent organism is called ANIMAL CLONING. The animal produced by this method is an exact duplicate of its parent.

In 1997 Ian Wilmut in the journal Nature announced about the cloning of sheep from a somatic cell nucleus from an adult female sheep. The technique used to clone the whole organism or animal is called REPRODUCTIVE CLONING.

Reproductive Cloning: 

A mature somatic cell such as skin cell or udder cell is taken from an animal which has to copy. Then the DNA of the donor animal's somatic cell is transferred into the egg cell which possesses its own DNA containing nucleus. Now the egg is allowed to develop into the early-stage embryo (in vitro) and then it is placed into the womb of an adult female animal this is how the animal gives birth to an animal that has same genetic characteristics as the donor animal. The newly generated animal is called  CLONE.

Reproductive cloning may require a surrogate mother for the development of the cloned embryo, like the most famous cloned animal "DOLLY  The sheep".


After the successful production of Dolly, many mammals have been cloned.

In 1998 two scientists Yangimachi and Teruhiko Wakayama (University of Hawaii) made an announcement for cloning of 50 mice from adult cells.

May 2003 (Italy, Laboratory of Reproductive Technology) ''PROMETEA'' first cloned horse was born by natural delivery and full- time pregnancy of its cloning mother.

October 17, 2004, the first cloned cat ''NICKY'' was born.

researches show that somatic nuclear transfer is successful in animals as well as Humans.