. Animal Cloning Cloning is the process of producing genetically identical individuals of an organism either naturally or artificially. In nature many organisms produce clones through asexual reproduction. Cloning in biotechnology refers to the process of creating copies of organisms or copies of cells or DNA fragments (molecular cloning).
Dolly was the first mammal (Sheep) clone developed by Ian Wilmut and Campbell in . Dolly, the transgenic clone was developed by the nuclear transfer technique and the phenomenon of totipotency. Totipotency refers to the potential of a cell to develop different cells, tissues, organs and finally an organism. The mammary gland udder cells (somatic cells) from a donor sheep (ewe) were isolated and subjected to starvation for days.
The udder cells could not undergo normal growth cycle, entered a dormant stage and became totipotent. An ovum (egg cell) was taken from another sheep (ewe) and its nucleus was removed to form an enucleated ovum. The dormant mammary gland cell/udder cell and the enucleated ovum were fused. The outer membrane of the mammary cell was ruptured allowing the ovum to envelope the nucleus.
The fused cell was implanted into another ewe which served as a surrogate mother. Five months later dolly was born. Dolly was the first animal to be cloned from a differentiated • Transgenic animals are used to produce proteins which are important for medical and pharmaceutical applications. • Transgenic mice are used for testing the safety of vaccines.
• Transgenic animals are used for testing toxicity in animals that carry genes which make them sensitive to toxic substances than non-transgenic animals exposed to toxic substances and their effects are studied. • Transgenesis is important for improving the quality and quantity of milk, meat, eggs and wool production in addition to testing drug resistance.