Monday, October 31, 2011
After graduating he did an internship at Columbia-Presbyterian Hospital in New York City and spent two years as a clinical associate at the National Cancer Institute where he cared for patients and researched the synthesis of immunoglobulins by myeloma tumors. He returned to Columbia-Presbyterian for two more years and then began his research career at the Rockefeller Institute working for Fritz Lippman in 1959, where he studied bacterial protein synthesis. Nathans began a Ph.D. program but did not complete it because he did not want to sit in any more lectures. In 1962 he moved to Johns Hopkins University in Baltimore, Maryland and worked for Barry Wood, who had been his teacher in medical school at Washington University. In 1969 he went to the Weizmann Institute of Science in Rehovot, Israel to learn about animal viruses and while he was there he received correspondence from his colleagues at Johns Hopkins about a restriction endonuclease enzyme. When he returned to America, Nathans, with the assistance of his graduate student Kathleen Danna, continued work that further established the function of restriction endonuclease enzymes.
Restriction endonucleases or restriction enzymes are enzymes that cleave double stranded DNA molecules at specific base sequences. Each enzyme has its own specific recognition sequence, that is a particular sequence of base pairs where it cuts the DNA molecule. These enzymes are used by bacteria to protect themselves from viruses. The enzyme with cleave viral DNA but leave the host DNA, which is methylated, alone. Over 6000 restriction enzymes have been now been characterized. These enzymes have been used to study genetics and find the locations of particular genes. They are also used in genetic engineering and the insertion of genes into genomic DNA. For his work characterizing restriction enzymes Nathans was awarded the 1978 Nobel Prize in Medicine, along with Hamilton Smith, who had made the initial discovery, and Werner Arber who had predicted the existence of restriction enzymes.
Other honors won by Nathans include election to the National Academy of Science and its U.S. Steel Foundation Award in Molecular Biology. Johns Hopkins has honored him co-naming the McKusick-Nathans Institute of Genetic Medicine after him as well as one of its medical school's colleges.
Nathans died on November 16, 1999.
DiMaio, Daniel, "Daniel Nathans: October 30, 1928 - Novermber 16, 1999"; Biographical Memiors Vol. 79, National Academy Press (2001)
Brownlee, Christian; "Danna and Nathans: Restriction Enzymes and the Boon to Modern Molecular Biology"; Proceedings of the National Academy of Science (2005)102:5909
Daniel Nathans Wikipedia Entry
Danile Nathans Nobel Autobiography
Monday, October 24, 2011
After graduating he went to the University of Lepzig, where he studied under Werner Heisenberg, completing his Ph.D. in 1928. His doctoral thesis introduced the concept of Bloch waves to explain the behavior of electrons in crystals, developing the theory of metallic conduction. After finishing his doctorate he took a tour of the various centers of experimental physics in Europe working for Wolfgang Pauli at the University of Zurich, Niels Bohr in Copenhagen, and Enrico Fermi in Rome, before returning to the University of Lepzig as a lecturer in physics. In 1933, soon after Hitler came to power in Germany, he emigrated to the United States, taking a position at Stanford University in Palo Alto, California. Bloch became Stanford's first professor of theoretical physics in 1939. During World War II he worked on nuclear power at Los Alamos Nuclear Laboratory and on ways to interfere with radar at Harvard University. After the war he returned to Stanford.
Bloch is most famous for his work developing the theory of nuclear induction and magnetic resonance. Atoms that have an uneven number of protons and/or neutrons have an intrinsic magnetic moment and angular momentum. This is called spin. When placed into a magnetic field nuclei will emit electromagnetic radiation, as their spin lines up with the magnetic field. The frequency of this emission depends on the strength of the magnetic field and the isotope. By measuring these emissions it is possible to determine the chemical structure in which the atom resides. This technique is used by chemists to determine the structure of compounds and it is used in medical imaging and is called magnetic resonance imaging, or MRI (the name was changed to remove the word "nuclear"). For his discovery of nuclear magnetic resonance Bloch won the Nobel Prize for physics in 1952, which he shared with Edward Mills Purcell who developed the theory simultaneously.
In 1952 Bloch became the first director of CERN, the European Organization for Nuclear Research, and he formulated its early policies regarding atomic research. Because as director he had little time for research he returned to Stanford a year later. In 1965 he served as president of the American Physical Society.
Bloch died on September 10, 1983.
Hofstader, Richard; "Felix Bloch"; Physics Today (1984)37:115-116
Hofstader, Richard; "Felix Bloch: 1905-1983" in Biographical Memoirs Vol. 64; National Academy Press; 1994
Felix Bloch Nobel Biography
Felix Bloch Wikipedia Entry
Wednesday, October 12, 2011
After finishing his doctorate he spent two years at the University of Gottingen and then went back to work for Max Planck as an assistant at the Institute for Theoretical Physics in Berlin. There von Laue met and became friends with Albert Einstein and von Laue contributed to the development and acceptance of Einstein's theory of relativity. In 1909 he went to the University of Munich where he lectured on thermodynamics, optics, and relativity. In 1912 he was appointed professor of physics at the University of Zurich. In 1913 his father was raised to the ranks of hereditary nobility and the "von" was added to his name. From 1914 to 1919 he was professor of physics at the University of Frankfurt and in 1916 he worked at the University of Wurzburg on vacuum tubes for use in military wireless communications. In 1919 he went till the University of Berlin, where he remained until 1943, when he became an emeritus, with his consent, one year before the mandatory retirement age.
Von Laue is most famous for the discovery of the diffraction of x-rays by crystals. The discovery originated from a discussion of the behavior of light moving through a regular crystalline medium. This caused von Laue to wonder what affect crystals would have on the much shorter wavelength x-rays. After the diffraction of x-rays by crystals was demonstrated von Laue worked the results out mathematically and published his results in 1912. This discovery paved the way for x-ray crystalography, the study of molecular structure of crystals using x-rays. For his discovery von Laue was awarded the Nobel Prize in physics in 1914. Other honors won by von Laue include the Max Planck Medal in 1932 and being made and officer in the French Legion of Honor in 1957.
Von Laue opposed the rising National Socialism movement in Germany and worked to help Jewish scientists emigrate from Germany. When Germany invaded Denmark in 1940 von Laue's golden Nobel Prize was dissolved in aqua regia by Hungarian chemist Georg de Hevesy, who was working at the Niels Bohr Institute at the University of Copenhagen where the prize was being kept, in order to prevent it falling into Nazi hands. Had the prize been discovered von Laue would have faced prosecution for exporting gold out of Germany. After the war de Hevesey found the solution, where he left it, of on the shelf of his laboratory. He precipitated the gold and returned it to the Nobel Society which recast the prize. After World War II von Laue was was seized by Operation Alsos, an Anglo-American operation to grab German nuclear scientists and materials, to prevent them from falling into the hands of the Soviets, and he was interred in Huntington, England at Farm Hill, a bugged house, with nine other German scientists. He returned to Germany in early 1946 and was the only German scientist invited to attend a conference on crystalography in London, where he was allowed to wander at will only four months after being released from internment. After the war von Laue worked to reestablish German science and he served as the director of the Max Planck Institute for Physical and Electrochemistry from 1951 to 1959.
On April 8, 1960, while driving to the laboratory, von Laue was involved in a automobile accident with a motorcyclist, who had just received his licence. Although he showed initial signs of recovery, he died on April 20th.
Von Laue, Max; My Development as a Physicist: An Autobiography, at iucr.org
Max von Laue Nobel Biography
Max von Laue Wikipedia Entry