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Famous Scientists in Genetics History - Oswald Theodore Avery

written by: Sonal Panse•edited by: Paul Arnold•updated: 8/6/2009

Oswald Theodore Avery was an American-Canadian researcher who is known for his work in discovering that DNA is the genetic material. Until his experiment, it was generally assumed that the genetic information was contained in the chromosomal proteins.

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    Oswald Avery - Research Career

    In 1907, Oswald Avery, a qualified physician, decided that his interest lay more in scientific research than in practising medicine. He began his research career that year as an associate director at the Hoagland Laboratory in Brooklyn; he also taught at the Long Island College Hospital which was affiliated with the Hoagland Laboratory. His early research was on yogurt bacteria and tuberculosis bacteria, and his paper on the secondary infections in pulmonary tuberculosis brought him to the attention of Rufus Cole, the Director of the Hospital of the Rockefeller Institute for Medical Research.

    On Cole's invitation, Avery joined the Rockefeller Institute in 1913 to work on the Hospital's pneumonia research program. His research here was principally concerned with the pneumonia causing bacteria Diplococcus pneumoniae. In the 1940s, when he was in his sixties, he became interested in the issue of heredity.

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    The Avery, MacLeod and McCarty Research on Heredity and DNA Genetics

    Genetic research in the twentieth century had benefited immensely from Frederick Griffith's 1928 Transformation experiment. This experiment had shown that pneumococcus bacterial strains, far from having fixed and non-interchangeable properties, were capable of transformation. Genetic information could be transformed from the virulent bacterial strain to the non-virulent one, conferring the latter with virulent properties, and this transformation could be passed on to succeeding bacterial generations.

    This clearly indicated gene transfer, but Griffith, and for many years several researchers after him, remained in the dark about how this transformation happened and about where the genetic information was stored in the chromosomes.

    Eukaryote chromosomes consist of proteins and nucleic acids that are composed of, respectively, 20 different amino acids and 4 different unitary building blocks. Since the number of amino acids is higher, it was thought that the diverse genetic information was more likely to be contained in the proteins.

    Then Oswald Avery and his colleagues at the Rockefeller Institute, Colin MacLeod and Maclyn McCarty, followed up on Griffith's research, and discovered that -

    • It was the DNA that contained the genetic information.
    • It was the DNA transfer from the virulent to the non-virulent strains that brought about the transformation process.

    They were able to discover this by using refined chemical compound extraction and isolation techniques and doing the following -

    • They removed the proteins from the virulent bacterial cells using protease enzymes, and then placed the cells in the non-virulent bacterial culture. The non-virulent bacteria transformed and became virulent. Since the proteins were missing, this meant that the genetic information was not contained in the proteins.
    • They then removed the DNA from the virulent bacterial cells using a deoxyribonuclease enzyme, and then placed the cells in the non-virulent bacterial culture. The non-virulent bacteria failed to transform. This meant that the genetic information was contained in the DNA.

    In 1944, they published an account of their experiment in Journal of Experimental Medicine. It aroused much interest, but their conclusion on DNA was questioned. Then, in 1952, Alfred Hershey and Martha Chase in their bacterial phage research work proved conclusively that DNA was indeed the carrier of hereditary matter. The year after that, in 1953, James Watson and Francis Crick discovered the DNA double helix structure.

    Avery's role in DNA research is an important one and he received many honors and acknowledgments, but, strangely, in one of their biggest oversights, the Nobel Prize Committee failed to consider him for the Nobel Prize.

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    Oswald Avery - Personal Life and Education

    Oswald Theodore Avery was born on 21 October 1877 in Halifax, Nova Scotia, Canada. His parents Joseph Francis Avery and Elizabeth Crowdy were English immigrants who had come to Canada in 1873. He had an older brother Ernest and a younger one Roy.

    In 1887, the Avery family moved to New York City's Lower East Side where Joseph Avery took up the ministry of the Mariner's Temple Baptist Mission Church. As a boy, Oswald Avery showed a keen interest in music and participated in church activities. After his brother Ernest died in 1892 and his father a few months later, the mantle of looking after the family fell on young Oswald.

    He attended the New York Male Grammar School and the Colgate Academy before going on to Colgate University. He read literature, was a member of the college band, and showed a talent for public speaking and debate. After receiving a B.A. in Humanities in 1900, he switched tracks and went on to study medicine at the Columbia University College of Physicians and Surgeons in New York. He was awarded a medical degree in 1904.

    On 1 August 1918, he became an American citizen, and the next month he was off to fight in the First World War. As a captain in the U.S. Army Medical Corps, he served from September 1918 to January 1919.

    In 1948, he left the Rockefeller Institute, where he had worked since 1913, and moved to Nashville to live near his brother Roy. He died here on 20 February 1955 at the age of 77.