Cohen, Stanley N. WORLD OF MICROBIOLOGY AND IMMUNOLOGY126•
taken from a frog. This experiment had great significance for
human application; bacteria containing human genetic infor-
mation could now be used to create the body’s own means for
fighting disease and birth disorders. The biological cloning
methods used by Cohen and other scientists came to be pop-
ularly known as genetic engineering. The cloning process
consisted of four steps: separating and joining DNA mole-
cules acquired from unlike species; using a gene carrier that
could replicate itself, as well as the unlike DNA segment
joined to it; introducing the combined DNA molecule into
another bacterial host; and selecting out the clone that carries
the combined DNA.
DNA research not only added to the store of scientific
knowledge about how genes function, but also had practical
applications for medicine, agriculture, and industry. By
1974, there was already speculation in the media about the
benefits that could accrue from gene transplant techniques.
The creation of bacteria “factories” that could turn out large
amounts of life-saving medicines was just one possibility. In
fact, insulin made from bacteria was just seven years from
becoming a reality. Still in the future at that time, but proved
possible within two decades, were supermarket tomatoes
hardy enough to survive cross-country trucking that taste as
good as those grown in one’s own garden. Using DNA tech-
nology, other plants were also bred for disease and pollution
resistance. Scientists also projected that nitrogen-fixing
microbes, such as those that appear in the soil near the roots
of soybeans and other protein-rich plants, could be dupli-
cated and introduced into corn and wheat fields to reduce the
need for petroleum-based nitrogen fertilizer. Cohen himself
said, in an article written for the July 1975 issue of Scientific
American:“Gene manipulation opens the prospect of con-
structing bacterial cells, which can be grown easily and inex-
pensively, that will synthesize a variety of biologically
produced substances such as antibioticsand hormones, or
enzymesthat can convert sunlight directly into food sub-
stances or usable energy.”
When news of this remarkable research became wide-
spread throughout the general population during the 1970s
and 1980s, questions were raised about the dangers that might
be inherent in genetic engineering technology. Some people
were concerned that the potential existed for organisms
altered by recombinant DNA to become hazardous and
uncontrollable. Although safety guidelines had long been in
place to protect both scientists and the public from disease-
causing bacteria, toxic chemicals, and radioactive substances,
genetic engineering seemed, to those outside the laboratory,
to require measures much more restrictive. Even though, as
responsible scientists, Cohen and others who were directly
involved with DNA research had already placed limitations
on the types of DNA experiments that could be performed,
the National Academy of Sciences established a group to
study these concerns and decide what restrictions should be
imposed. In 1975, an international conference was held on
this complicated issue, which was attended by scientists,
lawyers, legislators, and journalists from seventeen countries.
Throughout this period, Cohen spent much time speaking to
the public and testifying to government agencies regardingDNA technology, attempting to ease concerns regarding DNA
experimentation.
Cohen contended that public outcry over the safety of
DNA experiments resulted in an overly cautious approach
that slowed the progress of DNA research and reinforced the
public’s belief that real, not conjectural, hazards existed in
the field of biotechnology. In an article on this subject pub-
lished in 1977 for Sciencehe pointed out that during the ini-
tial recombinant DNA experiments, billions of bacteria
played host to DNA molecules from many sources; these
DNA molecules were grown and propagated “without haz-
ardous consequences so far as I am aware. And the majority
of these experiments were carried out prior to the strict
containment procedures specified in the current federal
guidelines.”
The controversy over the safety of DNA technology
absorbed much of Cohen’s time and threatened to obscure the
importance of other plasmid research with which he was
involved during those years. For instance, his work with bac-
terial transposons, the “jumping genes” that carry antibiotic
resistance, has yielded valuable information about how this
process functions. He also developed a method of using
“reporter genes” to study the behavior of genes in bacteria and
eukaryotic cells. In addition, he has searched for the mecha-
nism that triggers plasmid inheritance and evolution. Increased
knowledge in this area offers the medical community more
effective tools for fighting antibiotic resistance and better
understanding of genetic controls.
Cohen has made the study of plasmid biology his life’s
work. An introspective, modest man, he is most at home in
the laboratory and the classroom. He has been at Stanford
University for more than twenty-five years, serving as chair
of the Department of Genetics from 1978 to 1986. He is the
author of more than two hundred papers, and has received
many awards for his scientific contributions, among them the
Albert Lasker Basic Medical Research Award in 1980, the
Wolf Prize in Medicine in 1981, both the National Medal of
Science and the LVMH Prize of the Institut de la Vie in 1988,
the National Medal of Technology in 1989, the American
Chemical Society Award in 1992, and the Helmut Horten
Research Award in 1993. Cohen has held memberships in
numerous professional societies, including the National
Academy of Sciences (chairing the genetics section from
1988 to 1991), the Institute of Medicine of the National
Academy, and the Genetics Society of America. In addition,
he served on the board of the Journal of Bacteriologyin the
1970s, and was associate editor of Plasmidfrom 1977 to- Since 1977, he has been a member of the Committee on
Genetic Experimentation for the International Council of
Scientific Unions. Married in 1961 to Joanna Lucy Wolter,
and the father of two children, Cohen lives mostly near
Stanford University in a small, rural community. Free time
away from his laboratory and his students has been spent ski-
ing, playing five-string banjo, and sailing his aptly named
boat, Genesis.
See alsoMicrobial geneticswomi_C 5/6/03 2:04 PM Page 126