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Hershey (Hershey), Alfred

( American biologist, Nobel Prize in Physiology or Medicine, 1969)

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Biography Hershey (Hershey), Alfred
genus. December 4, 1908
American biologist Alfred Day Hershey was born in Ovosso (Michigan) in the family of Alma (Wilbur) and Robert D. Hershey. He attended a comprehensive school in Ovosso and Lansing before joining the Michigan State College (now - Michigan State University), where he earned a Bachelor of Science in 1930. Left in the state of Michigan for the completion of training, X. in 1934. received a doctorate in bacteriology, and then proceeded to work as an assistant at the Department of Bacteriology at Washington University in St. Louis (Missouri jackstay). Two years later he became a teacher in 1938. appointed assistant professor, and in 1950, Mr.. - Associate Professor.
In the early years of the University of Washington, X. conducted research under the guidance of Professor Bronfenbrenner, who studied bacteriophages since their discovery in 1915. Bacteriophage - a kind of virus affecting bacterial cells - is the simplest form of life and, like other viruses, is composed of protein and nucleic acids.
At the beginning of XX century. Scientists have shown that genes responsible for the inheritance of physical properties and are located in the chromosomes of the nucleus of each cell. Chromosomes contain proteins associated with nucleic acids, large molecules consisting of monosaccharides, phosphate and nitrogen bases, called purine or pyrimidine. Biochemists have discovered two types of nucleic acids: ribonucleic (RNA) and deoxyribonucleic (DNA). It was believed that only proteins that consist of connected in a chain of amino acids are complex enough to carry genetic information and DNA molecules were too monotonous and repetitive. However, in 40-ies. found, . that genes are composed of DNA and that DNA directs the synthesis of cell proteins, . enzymes and coenzymes (thermostable factors, . necessary for normal enzyme activity), thus was established the role of DNA in the control of biochemical processes in the cell.,
. In the period from 1940 to 1947
. Max Delbruck at Vanderbilt University in Nashville (Tennessee) studied the life cycle of bacteriophage. In collaboration with Salvador Luria at Columbia University, he proved that bacterial cells undergo a spontaneous mutation, in order to resist destruction under the influence of bacteriophages. The results of these studies, published in 1943, became a model for the analysis of experimental results in bacteriology. Delbruck, Luria and X. formed an informal group called the 'phage group', to explore the bacteriophage, in particular the mechanisms of its replication. 'Phage Group' encouraged other scientists to concentrate their efforts on the study of seven strains of bacteriophage, the harmful strain of E. coli In Escherichia coli, so you can easily compare the experimental results.
In 1946, Mr.. H. and Delbruck, conducting research independently, found that different strains of bacteriophage can exchange genetic material, if the same bacterial cell affects not one but several strains. Being a brilliant experimenter, unlike Delbrц?ck-theorist, that X. received irrefutable proof exchange of genetic information, which he called the recombination of genes. This is one of the first evidence of experiments, the recombination of genetic material between viruses.
In 1950, Mr.. H. resigned from the University of Washington to join worked in the genetic studies at the Carnegie Institution in Cold Spring Harbor on Long Island in New York. Electron microscopic analysis showed that the structure of the bacteriophage protein represented the head, encapsulated DNA, and a thin tail appendix. In 1952, Mr.. H. with geneticist Martha Chase discovered as bacteriophages affect bacterial cells. Use x. Chase and method of investigation was based on the fact that the phage protein does not contain phosphorus, but his DNA does not contain sulfur. After cultivation of the two parties bacteriophage - the one with radioactive phosphorus, the other with radioactive sulfur - Researchers have traced the path of the isotope in the process of interaction of bacteriophage with bacterial cell. They determined that the bacteriophage initially attached to the membrane of the bacterial cell to its protein tail appendix, located within the phage nucleic acid is then introduced into the bacterial cell. The separation of free shells bacteriophages, . containing sulfur isotope, . from bacterial cells, . labeled phosphorus, . suspension was placed in a mixer and stirred, . to destroy the attachment of the caudal appendages of the phage to the bacterial membranes,
. At the last stage suspension chasing through a centrifuge to separate the cell fraction from the liquid. The results of these experiments confirmed that DNA is the genetic material of phage, therefore, and all other organisms.
During the 50's and 60's. H. continued to study the biochemical structure and function of bacteriophage DNA. His research, he proved that the DNA of bacteriophage presented a chain - as distinct from the DNA of higher organisms - and some DNA bacteriophages have a ring structure. In addition, the DNA of one species differ from the DNA of other species.
In 1969. Nobel Prize in Physiology or Medicine was awarded to H., Luria and Delbruck 'for their discoveries concerning the replication mechanism and the genetic structure of viruses'. At a presentation at the awards Sven Gard of the Karolinska Institute noted the importance of these discoveries for the biochemistry, genetics and other fields of science. He added that all three winners 'can be rightly called the founder of a new science - molecular biology'.
Since 1962. until his retirement in 1974. H. headed the department of genetic studies in Cold Spring Harbor. 'Although it is difficult to conceive of people more dissimilar, . than Delbruck, . Luria and Hershey, . - Gunther Stent wrote Harvard Medical School, . - They had one thing in common - absolute honesty, . and it is this trait has led to the influence of these people on the whole scientific discipline '.,
. In 1943, Mr.
. Max Delbruck described the first meeting with X. In a letter to Luria: 'Prefers whiskey tea, easy to communicate, by the way, loves to travel in a sailing boat, valued independence'.
In 1946, Mr.. H. married Harriet Davidson, they had a son.
X. received an honorary degree from the University of Chicago, the Albert Lasker Award from the American national community health (1958) and the Kimber Genetics Award of the National Academy of Sciences (1965). He is a member of the American Academy of Arts and Sciences and National Academy of Sciences.

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