Remarks for the Memorial Service in Honor of Esther Lederberg

by Stanley Falkow

It is a privilege to be asked to share with you some of my memories of Esther Lederberg, and to try to put her considerable contributions to science in some modern day perspective.

Perhaps I should begin by telling you my first memory of Esther. This occurred in 1960 when she visited Walter Reed to visit my mentor, and her friend, Lou Baron. I was 26 years old and had just received my Ph.D. She was talking with Lou at a laboratory bench and she held in her hands a Petri dish that contained colonies of the typhoid bacillus. Her glasses were perched on her forehead and she held the plate of bacteria so close to her face I feared her nose would touch the colonies. This was a typical pose I saw a number of times although usually not with such dangerous microbes. She looked up when I entered the room and smiled. Those of you who knew her may remember that Esther had a very nice smile that brightened her face and showed her gentle but inquisitive nature. As soon as she opened her mouth I recognized her New Yawk accent and, I confess, she reminded me a great deal of my cousin Ruthie from the Bronx.

Esther was already considered to be one of the pioneers in bacterial genetics. It was then still a young field of investigation but was in the process of becoming the field of Molecular Biology. Esther had moved to Stanford just a few years before I met her. In the 12 years that she and Joshua Lederberg together with several students, most notably Norton Zinder, published an extraordinary number of original research papers. Esther discovered in 1951 that E. coli K-12, the microbe that was the foundation of the discovery of bacterial mating, also carried a bacterial virus which she named lambda. Eventually it was discovered that this virus was inherited in bacterial matings just like a bacterial gene in some cases but in others it was induced to replicate freely and destroyed the bacteria that harbored it. These fundamental findings were the foundation of a remarkable field of basic research spanning several decades.

A short time after this discovery she also participated in the development of the technique of replica plating. This technique was essential in the study of bacterial genetics, more specifically in the selection of mutants from among hundreds and hundreds of bacterial colonies on a plate. It was brilliantly simple: creative discoveries often are. She thought of using ordinary velveteen from a yard goods store to serve as a kind of rubber stamp. The tiny fibers of the velveteen acted like hundreds of tiny inocculating needles. The pad was carefully kept in the same orientation and used to inocculate a series of agar plates containing different media containing antibiotics or supplemented with essential nutrients such as amino acids and vitamins. Esther and Joshua used this technique as an indirect selective method to prove the spontaneous origin of mutants with adaptive advantages. All of us in the field adopted this method and it is still used in one form or another in many genetics laboratories around the globe. Esther a few years later participated in discovering that the basis of bacterial mating was a genetic element, called at the time the sex factor, or F for fertility. F was transmissible and extrachromosomal, a startling new concept at the time that led to the concept of bacterial plasmids.

All of these things foreshadowed our first meeting and I was appropriately in awe of her. I was just starting to use replica plating in my own work and Esther immediately told me what brand of velveteen to look for and to be sure to wash the velveteen before I used them and even what detergent to use to wash them.

In the ensuing years I saw Esther on and off at scientific meetings. Esther invariably arrived at a meeting carrying what to me looked like an enormous shopping bag from which often protruded sheets of music and a musical instrument called a recorder. The first time I saw this I made the mistake of asking her if this was some kind of toy she bought for a young relative. Big mistake. She also kept notebooks, snacks and lord knows what else in this portable closet she lugged into the meeting hall. Esther also always had a camera. It was not a fancy camera and in later years it was one of those throw away devices. A number of us received copies of prints of pictures that Esther had recorded at these meetings. My office still has copies of pictures Esther sent to me at meetings held in Berlin during the mid 1970's. She was a kind of Boswell of bacterial genetics and bacterial plasmids and I hope her collection of photographs if it still exists will be placed in a suitable archive to preserve them.

By the mid 70's because of the burgeoning field of recombinant DNA and biotechnology, Esther was asked by Stanley Cohen and several others of us to take on the role as a kind of curator of plasmids world-wide. She agreed. Because of her knowledge and the high regard she was held in by her colleagues, Esther was entrusted with the keeping of plasmids in a collection she kept here at Stanford. She distributed these to investigators around the globe. She was particularly helpful to young investigators and to those in foreign countries who were just starting out in science. She was also the arbiter of contentious quarrels among scientists about how plasmids and the jumping genes plasmids carried were named. Scientists are especially difficult about their pet names for things, and they resist using any nomenclature that is not their own. It has been said that a scientist would gladly wear the used underwear of a competitor rather than adapt their nomenclature. And Esther always prevailed in bringing difficult investigators into line because she had the patience to wear them down. Also, no one could out talk Esther -- is was possibly a Talmudic tradition of our ancestors.

Esther managed the plasmid reference center until her retirement. Others have/will/can tell you about Esther's life after she retired as an active scientist. My role is to try to say something about Esther's science. From a scientific perspective it is easy. Esther Lederberg has an assured place in the history of science. It will not be forgotten so long as there is a civilization.