What Is Cloning?

A clone is a group of genetically identical individuals (organisms and cells) all derived from the same ancestor by asexual or para-sexual methods. Clones are quite common among lower forms of life (prokaryotes and eukaryotes, plants and animals) as they commonly reproduce asexually.

Among the higher plants also, clones are not uncommon. In fact, many of our important food and ornamental plants like potato, sugarcane, ginger, mango, citrus (e.g. lemon, oranges), roses and others are commonly grown through vegetative (asexual) methods and are, therefore, clones.

Among the higher animals, however, clones are not found naturally and all attempts to develop clones failed till recently. It was recently that a group of biologists from the Roslin Institute, Edinburgh, England (Campbell et al, 1996) succeeded in cloning sheep. Their method involved transplanting nuclei from cell lines that had been established from very early (9 days old) sheep embryos to enucleated (from which nucleus had been removed) eggs. After the fusion of the donor cell nucleus with the enucleated egg, the reconstructed embryos were cultured for a few days in legated oviducts of sheep or on a well defined medium. Thereafter, they were implanted in the eves till full term (birth).