- Person
- Stanley Cohen
- Lived
- b. 1935
- Field
- Genetics
- From
- American
The story
Stanley Cohen came to genetics through medicine. After earning his medical degree at the University of Pennsylvania in 1960, he spent several years in hospital training and fellowships, and while at the National Institute of Arthritis and Metabolic Diseases he decided to combine patient care with basic research. As a postdoctoral researcher at the Albert Einstein College of Medicine in New York he studied how genes are switched on and off in a bacterial virus.
When he joined the faculty of Stanford University's School of Medicine in 1968, he chose a problem with obvious medical urgency. Bacteria were becoming resistant to antibiotics, and they often carried their resistance genes on plasmids, small rings of DNA that copy themselves independently and can pass from one bacterium to another. Plasmids were the obvious starting point for understanding how and why resistance spreads.
Working with Norman Davidson and Phillip Sharp at Caltech, Cohen's laboratory used electron microscopy to study the structure of these resistance plasmids, and showed how segments of bacterial DNA were linked to the formation of the plasmids that carried drug resistance. To go further, he needed to take plasmids apart, rejoin the pieces and grow the new combinations in living cells. Early efforts were frustrating, because the only way to break plasmids apart was to shear them mechanically into random pieces, which gave little insight.
The search for a precise way to cut and rejoin plasmid DNA led Cohen to Herbert Boyer and his DNA-cutting enzyme EcoRI, and in 1973 to recombinant DNA. The cloning work grew out of curiosity about basic biology rather than an attempt to build a new tool, a commitment to basic research that defined his career. In 1976 he also co-authored a proposal for a uniform system of naming bacterial plasmids, helping researchers around the world describe them consistently.
He later returned to the questions that started him off. His laboratory has continued to study how bacteria inherit and share resistance genes, how they adapt to antibiotics without mutations, and the mobile genetic elements known as transposons, which can jump between strains of bacteria and carry resistance with them.
Why it matters
Cohen's work on resistance plasmids helped explain how drug resistance spreads among bacteria, a growing threat to modern medicine, and it led directly to the invention of gene cloning.
About Stanley Cohen
Stanford geneticist who, with Herbert Boyer, invented recombinant DNA cloning in 1973, the technique that launched genetic engineering and the biotechnology industry.
More about Stanley Cohen
- Stanley Cohen co-invented genetic engineeringIn 1973 Stanley Cohen and Herbert Boyer first moved genes between organisms, inventing recombinant DNA, the technique behind human insulin and the biotechnology industry.
- Stanley Cohen helped build biotechnology in TaiwanBeyond his Stanford laboratory, Stanley Cohen helped develop research collaboration with Taiwan's Institute of Molecular Biology and a biotechnology industry in Taiwan.
- Stanley Cohen's plasmid pSC101 carried the first clonesStanley Cohen's plasmid pSC101, cut at a single site by Boyer's enzyme and carrying a tetracycline-resistance gene, became the vehicle for the first DNA cloning experiments in 1973.
- Stanley Cohen built tools to watch genes at workAfter inventing DNA cloning, Stanley Cohen developed techniques that use reporter genes to follow how genes behave in the cells of animals and other complex organisms.
- Stanley Cohen backed a safety pause on gene splicingStanley Cohen signed the 1974 letter calling for a voluntary pause on some recombinant DNA experiments until their risks could be assessed, and took part in the 1975 Asilomar conference.
- Stanley Cohen taught bacteria to take up new DNAIn 1972 Stanley Cohen’s Stanford lab showed that a calcium chloride treatment lets E. coli take up plasmid DNA and pass it on to their offspring.
- Stanley Cohen's patent was licensed to hundreds of firmsThe Cohen–Boyer recombinant DNA patents were licensed non-exclusively, for moderate fees, to 478 companies, spreading gene cloning across the biotechnology industry.
Sources
- Stanley N. Cohen Papers, biographical note National Library of Medicine
- Stanley Norman Cohen Wikipedia
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