Ian Wilmut: Cloning Pioneer

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    Syllabus: GS3/Science and Technology

    Context:

    • Ian Wilmut, the cloning pioneer of Dolly the Sheep, the first mammal to be cloned from an adult cell, has died.

    About

    • Dolly the Sheep, initially referred to as ‘6LL3’, was part of a series of experiments that were trying to develop a better method for producing genetically modified livestock.
    • These experiments were carried out by a team led by Professor Sir Ian Wilmut and were successful in cloning the first mammal from an adult cell at Edinburgh in 1996.
    • It was considered as one of the greatest scientific breakthroughs in the 20th century.

    How Ian Wilmut and team cloned a sheep?

    • The researchers used a cell from the mammary gland of a dead adult sheep to create a new living animal.
    • They stimulated the cell with electricity and added chemicals, which changed the adult DNA into an embryo.
    • They then put this into an empty sheep’s egg before implanting it into a surrogate sheep.
    What is a clone?

    – It is a living organism (such as a plant or animal), which shares the same genetic information as another organism.
    – However, their characteristics can be affected by random mutations which occur in their DNA.
    1. Clones have the same DNA, but they may not look the same or behave in the same way.

    Cloning of an animal:

    Somatic Cell Nuclear Transfer (SCNT), a cloning method, in which the nucleus of an egg cell is removed and replaced with the nucleus of a donor adult cell.
    – Because 99.9% of the cell’s DNA is contained in the nucleus as chromosomal DNA (with the remaining 0.1% of DNA found in mitochondria), the resulting animal will share almost exactly the same DNA as the original donor cell.

    Risks associated with cloning:

    – Cloned embryos are more likely to be lost during pregnancy than normal embryos, which accounts for the low success rate of cloning.
    – Animals with Large Offspring Syndrome (LOS) have growth defects and are considerably larger at birth than animals resulting from natural matings.
    1. LOS is more often found in cloned animals from livestock species, such as sheep, than in other cloned animals.
    – Mammals, even if they hit adulthood, have struggled with some adverse health effects that target the brain, heart, and liver, and they can even age prematurely.

    Way Forward:

    • Dolly was the first mammal to be cloned from an adult cell, and proved that specialised cells could be used to create an exact copy of the animal they came from.
      • It prompted other scientists to clone animals including dogs, cats, horses and bulls.
    • It opened up a lot of possibilities in biology and medicine, including the development of personalised stem cells known as iPS cells.

    Source: TH