Alfred Hershey(1908–97)

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Obituary evidence was needed to be convincing” and Alfred Hershey (1908–97) “diversity of experimental materials was often crucial to discovery”. One of the founding His next eight years were spent filling in the biochemical and genetic details of the fathers of molecular life-history of bacteriophage T2. Finally, biology following the discovery by Pete Davison that DNA molecules are fragile in solution, The 1940s saw the origins of molecular Hershey set about developing a way to biology and the beginnings of a proper work out the size of native, unbroken understanding of living systems. Until molecules. It was a desperately difficult then, biological phenomena were either project, but his studies were the essential reduced to questions of chemistry or precursor for much easier work by others. treated in abstract. There seemed to be no Al Hershey was, in many ways, the middle ground between the solidities of perfect experimentalist. No project was too biochemistry and the abstractions of difficult for him to tackle single-handedly, genetics, and it was not customary to ask no thought too much effort. Right to the how cells knew what they were doing. So end of his career he carried out his own the great leap forward largely depended experiments — he would even spend hours on scientists who were not wedded to the washing up the laboratory glassware technologies of an established discipline, (because, as he said, it temporarily spared and could focus their attention on the him the burden of thought). It was, simplest possible system — the bacterium perhaps, an extension of this principle that Escherichia coli and its viruses. Delbrück, made him say that ‘Hershey heaven’ was to Luria and Hershey (a physicist, a physician find an experiment that worked, and then and a microbiologist) played a crucial part to do it again and again. in these developments, and for this they He seemed to feel the responsibility of shared a Nobel prize in 1969. With the the rest of his career. His studies on linkage the world on his shoulders: only if he death of Al Hershey on 22 May, the last of and recombination in the genes of the T2 laboured to the utmost of his ability could the three has gone and an era has come to bacteriophage became increasingly everyone else avoid being misled. He an end. complicated and, some years later, divided every day in half; one half usually Hershey spent the first 16 years of his culminated in a review of almost starting at 9 a.m. and the other at about 9 career as an instructor in bacteriology at impenetrable obscurity; privately, he p.m., with dinner, sleep and breakfast Washington University, St Louis. The head admitted that the review was his way of interposed between each half. At almost of the department was Bronfenbrenner saying that he could not understand what any time of day or night, therefore, you who, like many people in those days, was going on. So, he changed to studying might find him either sitting motionless in believed that viruses were proteins that the chemical components of phage, and his chair, thinking and gazing at the somehow triggered their host cell into their fate during infection of a bacterium. ceiling, or cocooned in the privacy of some making more of the same so were not in Within a year, he and his assistant, Martha experiment or blissfully cleaning up any sense alive. Bronfenbrenner’s influence Chase, had shown that it is the DNA — not afterwards. His powers of concentration ensured that Hershey’s early publications the protein — that carries the viral genes tended to make him taciturn and absent- (on bacterial growth and virus–antibody and is responsible for the transfer of minded. But when he did talk, it was as if a interactions) were rather undistinguished. information from one generation of searchlight were being trained on a dark Certainly, they gave no hint of what was to particles to the next. This came to be landscape. He seemed to approach every come. known as the ‘blender’ experiment, subject, serious or trivial, as if he had never But in 1943 Hershey met Max because they had used an ordinary kitchen thought about it before (or, sometimes, Delbrück, just at the time when Delbrück blender to separate the empty protein even heard of it). This gave his utterances a and Salvador Luria were struggling with shells of the infecting virus particles from penetrating originality, which often caused the mathematics of mutation in bacteria. the infected bacteria. a gap in the conversation while his listeners Three years later, at the age of 38, Hershey Hershey’s evidence that genes are made desperately revised their opinions and reported that bacterial viruses contain of DNA rather than protein was less reordered their thoughts. genetic determinants which occasionally precise than Oswald Avery’s (for the His final project was perhaps the undergo spontaneous, inheritable changes bacterial transforming principle). hardest. Various circumstances forced him (mutation). Shortly afterwards, he showed However, Hershey’s experiment identified to retire in his mid-60s, and make space for that these determinants display genetic the chemistry of a group of conventional younger scientists. Typically, he made that linkage and form linear arrays — just like genes, whereas Avery’s result applied to a final transition without a murmur and, for the chromosomal genes of higher single obscure trait (the ability of a 20 years, sought satisfaction in other organisms. This established that bacterial bacterium to make a particular surface versions of Hershey heaven — the clearing viruses are a simple version of all living polysaccharide). For that reason many of forest to make a vegetable garden, and a creatures and, as Delbrück had imagined, people found Hershey’s experiment more search for the underlying meaning of that they could be used to investigate the persuasive. But together, the two sets of Western music. nature of the gene. results inaugurated the science of John Cairns In 1950 Hershey moved to the Carnegie molecular biology. As Hershey wrote, the John Cairns, formerly of the Harvard School of Institute of Washington’s unit at Cold development of molecular genetics showed Public Health in Boston, is at Hollygrove Spring Harbor and he remained there for repeatedly that “some redundancy of House,Wilcote, Charlbury OX7 3EA, UK.