Timeline

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.

1928: First Nuclear transfer experiment conducted by Hans Spemann

1938: Cloning with differentiated cells by nuclear transfer first envisioned by Hans Spemann.He proposed this 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'.

1944: American Oswald Avery located the nucleic acid DNA as the carrier of genetic information, instead of proteins in the cell.

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.

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. 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.

1977: Karl Illmensee claims to have cloned mice with only one parent

1979: Karl Illmensee claims to have cloned 3 mice

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: New DNA was created to inject into people to do the work of defective genes so as to boost the body’s defense.

1994: Dr. Ned First (U.S.) clones calves from cells of early embryos

1993: First humans cloned (U.S.). Cells taken from defective human embryos were developed up to 32-cell stage, then destroyed.

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: July – Wilmut’s team created Polly, the first genetically engineered sheep with human genes.

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