Cloning
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Cloning

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    Cloning Cloning Presentation Transcript

    • CLONING
      An Overview
    • GROUP MEMBERS
      HASSAN TARIQ (2008-EE-180)
      • Introduction and Overview
      • Cloning in Nature
      ZAIR HUSSAIN (2008-EE-177)
      • History of Cloning
      SAQIB SAEED (2008-EE-168)
      • How scientists clone cells
      UMAIR MAQBOOL (2008-EE-178)
      • Stem cells technology
      • Benefits of Cloning
    • Introduction and overview
    • Introduction
      Cloning: Creating copies of living matter
      The term clone (from the Greek word klōn, meaning “twig”) had already been in use
      • since the beginning of the 20th century
      • in reference to plants
      Clones have identical genetic makeup
      Abundant in nature
      Used by scientists to generate organisms with valuable traits
    • Historical Perspective
      Farmers started using it thousands of years ago
      Revolutionized in late 20th Century with the advent of genetic engineering
    • Cloning in Animals
      To generate animals with desirable traits
      To bolster endangered species
      Maybe in near future, extinct animals can be resurrected
    • Industrial Perspective
      Production of bacteria which can clean up environmental contamination
      Animals which can produce commercial ingredients e.g. protein
    • Importance for Humans
      Promises great advances in medicine
      Biomedical scientists plan to create animals with human diseases, so that cures can be experimented safely
    • Cloning in nature
    • In Bacteria and Plants
      Originated in nature
      Most organisms reproduce asexually
      Unicellular organisms reproduce by fission, a cloning method
      Plants like strawberries clone by producing runners
    • In Animals and Mammals
      Some species of fish, shrimps, lizards and frogs produce by parthenogenesis- from Greek word parthenos (“virgin”) and genesis (“birth”)
      Clones in mammals- genetic copies of each other
    • History of cloning
    • Initial Efforts
      1800’s- First try of using undifferentiated cells
      • Hans Dreisch separated a sea urchin embryo when it was just two cells
      • Both cells grew to adults
      Early 1900’s- Hans Spemann extended Dreisch’s work to salamanders
      • Determined that nucleus from embryo cell could direct the development of a complete organism
      • Published his results in 1938
      • Proposed a “fantastical” experiment
    • Early Frog Experiments
      1952- Spemann’s idea realized by Robert Briggs and Thomas King
      • Used cell nuclear transfer to insert DNA from a frog embryo cell into an enucleated frog egg
      • Resulting embryo grew into an adult
      • Early experiments using cell nuclear transfer were successful only when donor DNA was taken from an embryonic cell
    • Early Frog Experiments (Gurdon’s Method)
      1962- John Gurdon began cloning experiments using non-embryonic cells
      • Cells from intestinal lining of tadpoles
      • Exposed a frog egg to ultraviolet light, which destroyed its nucleus
      • Removed the nucleus from the tadpole intestinal cell and implanted it in the enucleated egg
      • Egg grew into a tadpole that was genetically identical to the DNA-donating tadpole
    • Impact of Gurdon’s Research
      Gurdon’s experiments captured the attention of the scientific community
      Tools and techniques he developed for nuclear transfer are still used today
      1963- J. B. S. Haldane, in describing Gurdon’s results, became one of the first to use the word clone in reference to animals
    • Glitches of Gurdon’s Method
      Tadpoles cloned in Gurdon’s experiments never survived to adulthood
      Scientists now believe that cells used may not have been differentiated cells
    • Mammal Cloning (Initial Efforts)
      Scientists turned their attention to cloning mammals
      Proved even more complex than earlier cloning experiments on invertebrates and amphibians
      1977- Karl Illmensee reported cloning mice from cells derived from early embryos
      • Illmensee’s findings were largely discredited because he used questionable laboratory techniques
      Agricultural researchers tried to clone cattle using somatic cell nuclear transfer, but failed
    • Mammal Cloning(Breakthrough)
      1984- First mammal cloned
      • Danish biologist Steen Willadsen
      • Working at Cambridge University in England
      Used nuclear transfer with DNA from early embryonic cells
      Two years later, a team of researchers at the University of Wisconsin cloned a cow through a similar approach
    • Mammal Cloning (Further Developments)
      1990’s- Cloning techniques advanced rapidly
      1995- Two lambs cloned
      • By Keith Campbell and Ian Wilmut at the Roslin Institute
      • From embryonic cells; named Megan and Morag
      • Scientists were able to keep the embryonic cells alive in culture for some time before beginning the cloning procedure
      Enabled scientists to modify an embryonic cell’s genes in culture before cloning
      Genetically modified livestock can be produced
    • Megan and Morag
    • HOW SCIENTISTS CLONE CELLS…
      Blastomere separationBlastocyst divisionsomatic cell nuclear transfer
    • Up till 1950’s
      Initial Efforts- Letting a single cell divide in a laboratory dish by ‘mitosis’
      Complex Techniques- Using animal embryos
      1950’s- Using cells that haven’t been differentiated yet (totipotent)
    • HOW SCIENTISTS CLONE CELLS…
      BLASTOMERE SEPARATION
      BLASTOCYST DIVISION
      SOMATIC CELL NUCLEAR TRANSFER
    • Blastomere Separation
      Fertilize an egg cell with a sperm cell in a laboratory dish till embryo is of about 4 cells
      Outer coating of embryo removed
      Placed in a solution to separate individual cells (Blastomeres)
      Each blastomere cultured separately
      Embryos implanted into surrogate mothers
    • HOW SCIENTISTS CLONE CELLS…
      BLASTOMERE SEPARATION
      BLASTOCYST DIVISION
      SOMATIC CELL NUCLEAR TRANSFER
    • Blastocyst Division
      Fertilized cell allowed to divide till mass is 30-150 cells (Blastocyst)
      Split Blastocyte into two
      Each half implanted in a surrogate mother
      Creation of identical twins
    • HOW SCIENTISTS CLONE CELLS…
      BLASTOMERE SEPARATION
      BLASTOCYST DIVISION
      SOMATIC CELL NUCLEAR TRANSFER
    • Somatic Cell Nuclear Transfer (Overview)
      Use cells of only ONE parent
      Somatic Cell (any body cell EXCEPT an egg or a sperm)
      Enucleated Egg Cell (egg with its nucleus removed)
      Merge both cells via fusion
      Only applicable on immature cells (either embryonic, or of young animals)
    • Somatic Cell Nuclear Transfer (Breakthrough- Birth of Dolly)
      In 1996, by improved somatic cell nuclear transfer method
      Donor cell made quiescent (less active)
      Transfer of genetic material from udder cell to an enucleated cell (from a second sheep)
      Resulting embryo was implanted into the uterus of a third sheep
      Now donor cells can be taken from adult animals
    • Egg Donor
    • Genetic Donor
    • Enucleated Cell
    • Embryo Development
    • Embryo Implantation
    • Birth
    • Somatic Cell Nuclear Transfer (Glitches)
      All genes are NOT in nucleus, so all genes of the clone are NOT those of the donor
      Since every organism is influenced by, both genes and the environment, so the clone’s life will be different from that of the parent
    • Stem cells and cloning
    • Basics
      At Blastocyte stage, embryonic cells can divide into ALL types of cells needed by the organism
      Scientists separate these cells and coax them to divide under special conditions (so that they can form any cell type)
      Humans maintain some stem cells in some tissue of body till death. But with aging, they lose ability to transform into different cell types (cells from bone marrow is exception)
    • Benefits
      Can be used to cure diseases
      If a patient receives stem cells cloned containing his own genetic material, then his/ her immune system would not reject them as foreign material
      Research going on to find cure for Parkinson’s, paralysis, damaged heart muscles, arthritis and diabetes mellitus
    • Results
      Still in experimental stage
      First clinical trial of curing patients suffering from Parkinson’s produced mixed results
      • Patients over 60 years old reported no improvement
      • Younger patients reported some improvement, but 15% of them sport irreversible side effects, like uncontrollable twitching
    • Risks
      If some error occurred during cloning, then all resulting cells will have same error
      However, in 2002, scientists at Rutgers University found comparatively fewer genetic mutations
      Risk of transferring disease via stem cells
      • Typically, scientists culture human stem cells with mouse cells
      • Mouse cells have some unknown nutrient that keeps human stem cells alive
      • So human cells can easily be infected by mouse cells
    • Benefits
      of
      Cloning
    • Benefits of Animal Cloning
      In Agriculture
      • Cloned cattle could produce higher yield of milk & meat
      • Can also produce drugs at commercial level
      In Laboratory
      • Create animals with human diseases
      • Can test cures on them safely
    • Cloning Endangered & Extinct Species
      2001- Gaur (endangered ox of South-East Asia) cloned successfully
      Plan to revive extinct species by cloning
      • Cells of last Spanish ibex (mountain goat) preserved for the same purpose
      Prerequisites
      • Cell with intact nucleus
      • Surrogate mother needed with similar genetic makeup, to implant the embryo
    • Can Humans Be Cloned…….?
      Impossible up till now
      In human embryo, number of cells become twice after every 24 hours
      • Not achieved yet in laboratory
      Not enough funding due to its controversial nature
    • Controversies
      People do not consider plant cloning as cloning: Main opposition is against animal cloning
      Arguments:
      • Man should not play God
      • Will increase social gaps, as babies with special traits, like beauty, athleticism, or intelligence can be created