DNA's Twists Of History

www.usnews.com Science & Technology 2/24/03

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1866 Gregor Mendel, an Austrian monk, shows how traits are inherited in pea plants.

1869 Swiss biochemist Johann Friedrich Miescher isolates "nucleic acid" from cells in pus.

1944 Oswald Avery and associates discover that DNA carries genetic information.

1953 James Watson and Francis Crick discover the double-helix structure of DNA.

1961 Sydney Brenner, Francois Jacob, and Matthew Meselson identify messenger RNA, which carries genetic information from DNA to the cell's protein-making factories.

1966 Teams led by Marshall Nirenberg and H. Gobind Khorana crack the genetic code, showing that sets of three "letters" on DNA spell out the 20 different components of proteins.

1973 Herbert Boyer and Stanley Cohen develop recombinant DNA technology--tools for cutting and splicing DNA to create genetically engineered organisms.

1975 At the Asilomar Conference in California, scientists agree on the need for safeguards in genetic engineering research.

1976 The Cambridge (Mass.) City Council, fearing rogue organisms, imposes a three-month moratorium on recombinant DNA research at Harvard University, halting lab construction.

1976 Boyer and venture capitalist Robert Swanson found Genentech, the world's first biotechnology company.

1977 Scientists including Walter Gilbert and Frederick Sanger devise ways to sequence DNA.

1978 Genentech develops recombinant human insulin, eventually marketed asHumulin, the first drug made by genetic engineering.

1980 The Supreme Court rules that a genetically modified organism, a bacterium developed by General Electric Co. to break down oil spills, can be patented.

1983 Kary Mullis conceives the polymerase chain reaction (PCR), a method for multiplying traces of DNA into usable amounts. PCR soon becomes a major tool in research, medicine, and forensics.

1983 With blood samples collected by Nancy Wexler from a large family in Venezuela, James Gusella and others identify the gene responsible for Huntington's disease, leading to the first genetic test for a disease.

1984 Alec Jeffreys develops DNA fingerprinting, a technique for identifying individuals from their DNA that is a boon to forensics and paternity cases.

1987 Tommie Lee Andrews is convicted of rape in Orlando based on DNA fingerprinting--the first such case in the nation.

1988 Harvard geneticists receive the first U.S. patent for a genetically altered animal, the oncomouse, engineered to develop cancer.

1989 DNA evidence for the first time overturns a conviction, clearing Gary Dotson of an Illinois rape.

1990 PCR brings back the dinosaurs in Michael Crichton's bestseller Jurassic Park by amplifying traces of dinosaur DNA in prehistoric biting insects preserved in amber.

1990 An international effort to sequence the human genome begins.

1990 Researchers at London's Hammersmith Hospital are the first to screen test-tube embryos for genetic defects before implanting them.

1994 Scientists locate the BRCA-1 gene, responsible for almost half of the breast cancers linked to heredity.

1994 The Flavr Savr tomato, designed to ripen slowly, is the first genetically altered food approved by the FDA.

1997 Scotland's Roslin Institute announces the birth of Dolly the lamb, the first mammal to be cloned from an adult cell.

1997 DNA shows that Cheddar Man, a 9,000-year-old pile of bones at the Natural History Museum in London, is the direct ancestor of a living Englishman.

1997 The Ernest Orlando Lawrence Berkeley National Laboratory acknowledges secret genetic testing of employees for the sickle-cell trait.

1997 DNA from 40,000-year-old Neanderthal bone indicates that modern humans did not interbreed with these prehistoric people.

1997 Gattaca--a sci-fi film named for DNA's letters--depicts human genetic manipulation.

1998 DNA testing links President Clinton to the stain on Monica Lewinsky's dress.

1998 Researchers for the first time sequence the entire DNA of an animal, theroundworm C. elegans.

2000 Clinton issues an order barring federal agencies from using genetic information in hiring, firing, or promotion.

2000 Researchers complete the first rough drafts of the human genome.

2000 Traces of genetically modified corn, approved only for animal feed, are found in taco shells, prompting recalls.

2002 Rice is the first crop to have its genome decoded.

2003 Dolly the sheep is euthanized because of health problems that raise questions about cloning safety. -Carol Hook