Frederick Griffith's work with streptococci and pneumococci bacteria gave him an important place in the history of biology. However, the impact of his work on the science of genetics was even more crucial, although it is not clear whether Griffith himself ever realized his contributions to this field. His classic experiments, published in a single seminal paper in 1928, showed that some strains of bacteria could appropriate the disease-causing characteristics of other strains. Although interesting enough for the light it shed on the virulence of certain organisms, what he called the "transforming principle" was also the first clear evidence linking DNA to heredity in cells.
The details of Griffith's life are not completely known, partly because he lived very quietly and reclusively and partly because the importance of his work was not appreciated until well after his death. He was born in 1879 (some sources say 1877 or 1881) in Hale, in Cheshire, England, and he attended Liverpool University. His one older brother, A. Stanley Griffith, was also a microbiologist. After his graduation from the University of Liverpool in 1901, the younger Griffith worked for the Liverpool Royal Infirmary, the Thompson Yates Laboratory, and the Royal Commission on Tuberculosis. In 1910 he began working for the government, in what would later be called the Ministry of Health, under the supervision of Arthur Eastwood. The facilities were primitive, but as a friend wrote of Griffith in The Lancet: "He could do more with a kerosene tin and a primus stove than most men could do with a palace."
Griffith researched many kinds of microorganisms, but his most important work dealt with pneumococcus, the bacteria that can cause pneumonia. All types of these bacteria can theoretically cause disease, but some types (such as Type III) cause disease more readily than others (such as Type II). When Griffith began his work, he knew that the difference in virulence was due to a polysaccharide coating, or capsule, on the Type III organisms which protected the bacteria from the host's immune system. The Type II pneumococcus lacked the "capsule" that protected Type III. Bacterial colonies with capsules are called (S) colonies, and ones without capsules are called (R) colonies. They look quite different and are easy to identify in culture.
Research on Bacteria is Precursor to Genetics
Griffith injected some mice with Type II pneumococcus alone and other mice with Type III pneumococcus that had been killed by heating. None of the mice developed pneumonia. When he injected mice with both live Type II and dead Type III pneumococcus, however, the mice not only developed pneumonia, but live Type III bacteria could be extracted from their blood. Somehow the Type II bacteria had made protective capsules for themselves, "transforming" themselves into Type III. They had apparently acquired the characteristics from the dead Type III bacteria.
After later researchers managed to obtain transformed bacteria in a test tube instead of a live animal, work in the area declined for awhile. It was not until 1944 that Oswald Avery, Colin Munro Mac Leod, and Maclyn Mc Carty took up Griffith's experiments again and tried to explain his results. They extracted the active transforming principle from Type III (S) pneumococcus and showed preliminarily that it was DNA. In "Studies on the Chemical Nature of the Substance Inducing Transformation of Pneumococcal Types," they cautiously stated that if DNA actually proved to be the transforming principle, "... then nucleic acids of this type must be regarded not merely as structurally important but as functionally active in determining the biochemical activities and specific characteristics of pneumococcal cells."
DNA is a very long molecule, or polymer, made up of linked, individual units. There are only four of these units, or nucleotides, however, scrambled in varying order along the length of the DNA. Biochemists of the time knew about nucleic acids, but they were certain that it was protein that caused inheritance; they were not inclined to suspect much of a hereditary role for a molecule (DNA) that seemed too simple for such a complex activity. Finally, in 1952, other researchers used radioactive labeling to prove that DNA was indeed the hereditary material that Griffith had first observed transforming bacteria. Griffith's work may thus be seen as pivotal in beginning the science of molecular biology.
Little is known about Griffith's private life except that he enjoyed skiing, walking, and vacations at his country cottage in Sussex. In the first Griffith Memorial Lecture, given in 1966, W. Hayes said, "Fred Griffith has been described as a shy and reticent man, whose quiet kindly manner, and his devotion to his job, made him a lovable personality to those few who got to know him." He published very little, but what he did was of a very high quality, and Hayes believed that this "... must be ascribed to an innate humility and capacity for self-criticism, so that he offered to posterity only those products of his research which he judged to be new and important." Griffith and a longtime colleague at the Ministry of Health, the bacteriologist William M. Scott, were killed in 1941 during the bombing of London when a bomb blew up the building in which they worked.
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