History of cloning – timeline
Look at the major milestones in the development of cloning through the years:
1608: Zacharias Jansen invented the microscope, an instrument that reveals the microcosm.
1822: Gregor Mendel, Father of Modern Genetics, born. He formed his laws of inheritance from experimenting with plants.
1902: Walter Sutton proves chromosomes contain genetic information
1902: Hans Spemann divided a salamander embryo into halves and showed early embryo cells contains all the genetic information necessary to create a new organism.
1907: Thomas Hunt Morgan begins work on first „chromosome map‟. The American
scientist made the map to show the location of genes. He used fruit flies in his tests because of their simple genetic structure and rapid breeding.
1928: First Nuclear transfer experiment conducted by Hans Spemann
1932: First electron microscope made by 2 Germans Ernst Ruska and Max Knoll.
1938: Cloning with differentiated cells by nuclear transfer first envisioned by Hans Spemann. He published his book “Embryonic Development and Induction” where he wrote up the results
of the nuclear transfer experiment in 1928. He also proposed in this book that experiments
on cloning organisms by extracting the nucleus of a differentiated cell and inserting it into an enucleated fertilized egg, which he called the „fantastical experiment‟. However, Spemann did not know how to do it.
1944: American Oswald Avery located the nucleic acid DNA as the carrier of genetic
information, instead of proteins in the cell. While investigating transformation in bacteria,
where bacterium form capsules when in contact with substance from bacteria with capsules, he concluded that the „substance‟ contained the genes causing the capsules, and determined this „substance‟ as DNA.
1950: Alfred Hershey and Martha Chase use radioactively labelled E. coli to prove that DNA
and not proteins had penetrated interior of cells and was the true carrier of heredity.
1952: Briggs and King cloned tadpoles
1953: Shape and structure of DNA discovered by American James Watson and English Francis Crick.
1958: F.S. Steward (U.S.) grew complete carrot plants from differentiated carrot root cells, showing that cloning from differentiated cells is in fact biologically possible.
1962: John Gurdon claimed to have cloned frogs from adult cells
1964-6: Marshall Nirenburg, Heinrich Mathaei, and Severo Ochoa cracked the genetic code. They determined what codon sequences corresponds to which amino acid. This led to a
massive increase in genetic engineering research.
1967: Enzyme DNA ligase was isolated. DNA ligase binds strands of DNA together. It is essential in recombinant DNA technology.
1968: American researchers Matthew Meselson and Franklin Stahl show that old strands of DNA act as templates for formation of new strands and that synthesis of new DNA occurs while old chromosome is in process of uncoiling.
Americans George W. Beadle and Edward L. Tatum worked with bread mould which led to the hypothesis "one gene, one enzyme."
1973: Two U.S. researchers, Herbert Boyer and Stanley Cohen, conducted the first successful experiment on recombinant DNA.
Boyer and Cohen created the first recombinant DNA organism using recombinant DNA
technology, or gene splicing, which allows the manipulation of DNA. They removed plasmids,
small rings of DNA located in a cell‟s cytoplasm, from a cell. Using restriction enzymes, they
cut the DNA at precise positions and then recombined the DNA strands in their own way using DNA ligase enzyme. They then inserted the altered DNA into E. coli bacteria. The bacterial
cells could be made to produce specific proteins using gene splicing. This technology was a major breakthrough for genetic engineering.
1977: Karl Illmensee claims to have cloned mice with only one parent
1978: David Rorvik‟s book, „In His Image: The Cloning of a Man‟, released.
1978: Louise Brown (U.K.), the first child conceived by in vitro (outside the body) fertilization,
1979: Karl Illmensee claims to have cloned 3 mice.
1980: U.S. Supreme Court rules that a genetically created artificial new bacterium is patentable material.
The first patent granted on a living thing – a microorganism genetically engineered to
digest waste created by spills from tankers or offshore oil rigs. The U.S. Supreme Court ruled that „a live, human made microorganism is patentable material.
1983: The polymerase chain reaction (PCR) technique for rapid DNA synthesis devised by Kary B. Mullis.
1984: Steen Willadsen cloned a sheep from embryo cells – the first mammal proved to be
cloned using nuclear transfer.
1986: Willadsen cloned a cow from differentiated, 1 week old embryo cells, showing that genetic information of a cell did not decrease as a cell specialize.
1990: Tracy the sheep created to produce useful proteins in milk.
1990: Gene therapy first used to treat a 4-year old girl with an immune disorder. New DNA was injected to do the work of defective genes so as to boost the body‟s defense.
1990: Beginning of the Human Genome Project.
1993: First humans cloned (U.S.). Cells taken from defective human embryos in an infertility clinic are grown in vitro and developed up to 32-cell stage, then destroyed.
1994: Dr. Ned First (U.S.) clones calves from cells of early embryos
1995: Dr. Ian Wilmut and Keith Campbell (U.K.) create the world's first cloned sheep, Megan and Morag, from differentiated embryo cells.
1996: July – Dolly, the first cloned sheep, was cloned by nuclear transfer from adult cells
1997: Scientists at Oregon Regional Primate Research Center create first primates from DNA taken from cells of developing monkey embryos. The two rhesus monkeys, Neti and Ditto, are not genetically identical since 2 different embryos were used.
1997: July – Wilmut‟s team created Polly, the first genetically engineered sheep with human
1997: Researchers at the University of Bath (England) created headless tadpoles. Possible future uses for the technology include the tissue bank.
1998: Yanagimachi‟s team created 22 mouse clones with nuclear transfer, and also clones of clones.
1998: Experiments with cell-repair genes show that it may be possible to extend human lifespan by 40%. Researchers said that old people can still be active and mostly free of diseases.
1998: An endangered breed of New Zealand cattle was cloned by nuclear transfer, opening
the door to cloning to save endangered species.
1999: Calves were cloned from frozen cells taken from a Japanese beef bull. The experiment, led by Dr. Xiangzhong Yang, proved that cells can be stored for later cloning.
1999: September – Tetra, the first cloned monkey, cloned by embryo splitting.
1999: December - Dolly may show premature aging
2000: May – Cloned cow shows that cloning can rejuvenate cells
th 2000: June – Human Genome Project and Celera Genomics Corp. announce on June 26
that they have completed a working draft of the human genome