SOMATIC CELL NUCLEAR TRANSFER SCNT By Swas SOMATIC CELLS o These are any cell in the body that are not gametes sperm or egg germ cells cells that go on to become gametes or stem cells o Essentially all cells that make up an organism s body and are not used to directly form a new organism during reproduction are somatic cells o The word somatic comes from the Greek word soma which means body NUCLEAR TRANSFER Transplantation The introduction of the nucleus from a cell into an enucleated egg cell an egg cell that has had its own nucleus removed HISTORY Dreisch 1885 First ever embryo twinning observed in a Sea urchin by Hans Adolf Edward 1928 The cell nucleus controls embryonic development 1958 First successful nuclear transfer Briggs and King transferred the nucleus from an early tadpole embryo into an enucleated frog egg a frog egg from which the nucleus had been removed The resulting cell developed into a tadpole 1975 First mammalian embryo created by nuclear transfer J Derek Bromhal transferred the nucleus from a rabbit embryo cell into an enucleated rabbit egg cell 1996 Dolly the Sheep first mammal to created by somatic cell nuclear transfer Process Nucleus is removed from an egg cell The de nucleated egg cell is prepared Somatic cell are fused It divides to form an embryo stem cells Can also be implanted in a uterus to make a cloned animal Ex Dolly the Sheep DOLLY THE SHEEP In the 1990s British developmental biologist Ian Wilmut and his team of scientists at Roslin Institute in Scotland used nuclear transfer to produce sheep clones the best known of which was the Finn Dorset sheep Dolly born in 1996 This research stimulated renewed interest in the ability of egg cells to reprogram differentiated nuclei The technique used to generate Dolly inspired the development of SCNT which has become an important technique in stem cell research and in understanding the cellular mechanisms controlling embryonic development and nuclear reprogramming USES 1 To obtain stem cells 2 Sem cell derived gametes 4 To clone early stage embryos 3 Organoids 5 Exosomes 6 Transgenic animal models for biomedical applications MAJOR APPLICATIONS 1 Therapeutic cloning It is the transfer of nuclear material isolated from a somatic cell into an enucleated oocyte in the goal of deriving embryonic cell lines with the same genome as the nuclear donor 2 Reproductive cloning It is defined as the deliberate production of genetically identical individuals 3 Transgenic animals ADVANTAGES This process permits the production of perfect match tissues Patients with a disease could have stem cells produced that match their own cells and these stem cells wouldn t be seen as foreign and attacked by the These stem cells could become nerve kidney heart or whatever type of cell is patient s immune system needed to treat the diseases To restore endangered species It allows for the targeted deletion knockout of genes in farm animals Alternative method for generating transgenic animals as bioreactors pharming LIMITATIONS Early fetal morality The number of times that a given individual can be cloned is limited by the number of eggs that can be obtained About 40 50 of the reconstructed embryos develop to a stage suitable for transfer only about 10 result in the birth of a live cloned calf currently only about 4 5 of cloned embryos originally constructed actually make it to become calves Clones are not strictly identical since the somatic cells may contain mutations in their nuclear DNA It can be inefficient due to stresses placed on both the egg cell and the introduced nucleus this can result in a low percentage of successfully reprogrammed cells