Maclyn McCarty, the Transforming Principle & DNase: Clinching Evidence for DNA as the Material Basis of Genes
The 1944 discovery that DNA was the material basis of heredity by a trio of microbiologists led by Oswald Avery at Rockefeller University, is arguably the most significant discovery for the progress of biology in the twentieth century. Although it was met with considerable skepticism and even outright opposition at first, Avery and the transforming principle have gone on to receive historical recognition, at least in some quarters. The history of the events that unfolded in the years immediately following the original publication, however, remains little known to this day, overshadowed by other discoveries around the very same material. For example, in a series of experiments immediately following the 1944 demonstration, Maclyn McCarty, the third author on the original paper, showed that the specific biological function of virulence conferred by the transforming principle was specifically inactivated by DNA-degrading enzymes (desoxyribonulease or DNase), but not by proteinases or ribonucleases, namely enzymes that destroyed proteins and RNA, respectively. Although this finding should have been conclusive evidence in favor of the notion that the transforming principle was composed of DNA, its significance appears have been overlooked by most of Avery et al’s contemporaries. In my talk I propose to make a case for the scientific and historical significance of McCarty’s work, and attempt to assess the indifferent, if not negative, reception to his DNase papers.
Lost Disciplines, Lost Legacies: Irene Manton, Biologist of the Cold War
There is a renowned focus on military and medicine in Cold War science. The disciplines of evolutionary biology and cytology remain on the outskirts. When British evolutionary biologist, Irene Manton, transitioned from traditional light microscopy to the electron microscope, after the Second World War, her disciplinary identity was in flux. As a plant cell cytologist, who traced the evolutionary histories of ferns, she worked at the cutting edge of her field. It is only in retrospect that her specialism has been designated 'experimental taxonomy' (constituting a merger of traditional taxonomical practices with newer experimental methods). This paper considers the fate of this nascent area of investigation, in the context of its inevitable post-war encounter with a new and more powerful microscope –the electron microscope.
In the changing post-war disciplinary landscape, this apparently obscure area of research takes on a special significance, in demonstrating a case of reciprocal knowledge transfer, between the University of Leeds, UK, and the American based Rockefeller Institute. It presents a revised viewpoint on the activities of the Rockefeller Foundation, well-known for its role in the transfer of physical technologies (such as the electron microscope and the ultracentrifuge) into biology, prior to the war, and for its part in forging the new post war discipline of Molecular Biology. Recent scholarship on the history of Cell Biology argues the discipline has been overshadowed by Molecular Biology, while ironically this work itself overshadows vulnerable historical actors (women scientists like Manton). This paper seeks to explain why this has happened.
Scientific Creativity in Peripheral Locations: The Madras Triple Helix Model of G. N. Ramachandran
The University of Texas - El Paso
The name of the Indian scientist G. N. Ramachandran is associated forever with the discovery of the structure of Collagen. Present in almost all connective tissues, such as skins, bones or muscles, collagen was the third great discovery in biophysics right after the discovery of alpha helix by Linus Pauling and the DNA double helix by Crick and Watson. Unlike the first two however, this third discovery came from a young peripheral scientist who worked from an obscure newly-founded Department at the University of Madras. The discovery of the triple helix structure in collagen, and the subsequent creation of the Ramachandran Plot, was thus truly a case when a peripheral scientist won the race for discovery against numerous Goliaths in the field. In this presentation, my goal will be to trace the outlines of the reasoning that led Ramachandran from his early X-ray diffraction diagrams to the final triple helix structure and the controversy that created the Ramachandran Plot.