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The annual "degree granting" party of Max Delbrück's phage group held in the house shared by Meselson and Stahl at Caltech. (L-R) Harry Rubin, Max Delbrück, Rene Cohen, Matt Meselson, Frank Stahl.
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Frank Stahl and his wife Mary at a party, 1956.
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Frank Stahl and his wife Mary. The photo was taken in 1956 by Matt Meselson.
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1958 Cold Spring Harbor Laboratory meeting. Frank Stahl answering a question as Max Delbrück looks on.
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Franklin Stahl during a recent interview at the University of Oregon, 1999.
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1958, Matt Meselson at Caltech.
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Matt Meselson and Frank Stahl in Oregon on a walk in the Cascade Mountains, 1984.
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Matt Meselson at Harvard, 1999.
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Arthur Kornberg, 1970s.
Audio Glossary
Deoxyribonucleic acid (DNA), DNA replication, NucleotideVideo Interviews
Frank Stahl is a Professor of Biology at the University of Oregon. His current research deals with characterizing and comparing the genetic recombination systems of yeast and coliphage.
Clip 1 (0:55)
Describing his first meeting with James Watson and Matthew Meselson.
Clip 2 (0:20)
Describing how he first met Matthew Meselson.
Clip 3 (0:45)
Recounting how the seminal "Meselson-Stahl" experiment was only performed 3 times, with one set of results discarded due to mislabelled tubes!
Clip 4 (0:35)
On whether, upon completing their seminal experiment, Max Delbrück locked Meselson and Stahl in a cabin to force them to write up their results for publishing - how the great scientists are always looking to the "next result."
Clip 5 (0:41)
Comparing the early days of molecular biology research to today's informatics - heavy genome era.
Clip 6 (0:35)
Advice for young, aspiring scientists.
Matt Meselson is a Professor in the Department of Molecular and Cellular Biology at Harvard University. His laboratory studies sexual reproduction and genetic recombination, and how and why they are maintained in evolution.
Clip 1 (1:45)
Explaining density gradient centrifugation.
Clip 2 (0:49)
The three models of DNA replication - semi-conservative, conservative, and dispersive - and whether bias played a role in designing/interpreting the experiment.
Clip 3 (0:49)
How Meselson came to read the Watson and Crick paper, then think about ways to experimentally test how DNA replicates.
Arthur Kornberg is Professor Emeritus in the Department of Biochemisty at Stanford University. Dr. Kornberg did the work on DNA replication.
Clip 1 (00:29)
Finding the enzymes in their crude extracts.
Clip 2 (00:49)
Some of the different kinds of DNA polymerases.
Clip 3 (00:21)
Family background.
Matthew Meselson and Franklin Stahl invented the technique of density gradient centrifugation and used this to prove that DNA is replicated semi-conservatively. Arthur Kornberg identified and isolated DNA polymerase I — one of the enzymes that can replicate DNA. MATTHEW STANLEY MESELSON (1930-)
Matthew Meselson was born in Denver, Colorado. He had always wanted to be a chemist and had a huge lab workshop set up in his family's basement and garage. Meselson studied chemistry at the University of Chicago and then did his graduate work at the California Institute of Technology with Linus Pauling. Meselson's thesis project was to use X-ray crystallography to figure out the structure of a specific protein. In 1954, Meselson went to Woods Hole to be a teaching assistant. Here, Meselson met Franklin Stahl — a post-doctoral fellow who was taking courses to learn some molecular biology techniques. Meselson and Stahl had a profitable summer during which they discussed theory and possible experiments. They were especially interested in trying to devise a way to prove or disprove Watson and Crick's model of semi-conservative replication. Meselson and Stahl found themselves so in tune with each other's ideas that they agreed to work together on devising the right experiment. Stahl got a post-doctoral position in Caltech, and by 1957 the two had the experimental proof for the semi-conservative replication of DNA. They did this by inventing a new technique called density gradient centrifugation, which uses centrifugal force to separate molecules based on their densities. Their "classic" paper was published in 1958 and their experiment has been called "one of the most beautiful experiments in biology." In 1957, while doing the experiments with Stahl, Meselson gathered enough data to finish his Ph.D. with Pauling. He then stayed at Caltech, first as a research fellow and then as an assistant professor of chemistry. Meselson worked on phage recombination — showing that recombination results from the splicing of DNA molecules. In 1960, François Jacob and Sydney Brenner came to his lab at Caltech where they obtained the data necessary to prove the existence of mRNA. In the fall of 1960, Meselson accepted the position of associate professor of molecular biology at Harvard University, where he is currently the Thomas Dudley Cabot Professor of the Natural Sciences. He discovered the enzymatic basis of host DNA protection, where the cell recognizes its own DNA by adding methyl groups to it. Foreign DNA will be attacked and destroyed by restriction enzymes but host, methylated, DNA remains intact. Meselson also discovered the process of DNA mismatch repair, which allows cells to fix mistakes in DNA. Currently, Meselson's research interest has to do with the evolution of sexes, and he is using the small invertebrate Rotifera as a model system. Since 1963, Meselson has been concerned about the use of chemical and biological weapons in warfare. He has acted as a consultant for a number of government agencies, and participated in scientific studies that studied the effects of accidental and misuse of biological weapons. Meselson is the co-director of the Harvard Sussex Program on Chemical Biological Weapons (CBW) Armament and Arms Limitation. This is a program that attempts to set limits on the use of chemical and biological weapons. Meselson is also the co-editor of The CBW Conventions Bulletin. FRANKLIN WILLIAM STAHL (1929-)
Franklin "Frank" Stahl was born in Boston. He received a B.A. from Harvard University in 1951. Stahl then went to the University of Rochester for graduate work. While finishing up his Ph.D., Stahl attended a molecular biology course at Woods Hole. The course was being taught by James Watson and Francis Crick, and it was here that Stahl met Matthew Meselson. As they both tell it, during a break in the course, Meselson introduced himself to Stahl who was sitting under a big tree drinking and selling gin and tonics. At the time, Meselson was a graduate student at the California Institute of Technology; he was interested in exploring new methods of experimentation. Stahl had the experience and the math to help Meselson design these experiments. They hit it off right away and made plans for Stahl to do post-doctoral work at Caltech. In 1957, Stahl and Meselson developed the technique of density gradient centrifugation and used it to prove that DNA was replicated in a semi-conservative way, as predicted by Watson and Crick in their 1953 paper. Meselson and Stahl's paper appeared in 1958. In 1959, Stahl accepted a position at the University of Oregon where he is now a distinguished professor of Molecular Biology. His current research interest is on the mechanisms of genetic recombination. ARTHUR KORNBERG (1918-)
Arthur Kornberg was born in Brooklyn, New York. His parents emigrated from Eastern Europe and neither of them had a formal education. Kornberg's father worked in a New York sweatshop to support his family. Later, he and his wife opened a small hardware store. Kornberg's parents believed that education was very important and encouraged their children to stay in school. Kornberg was an excellent student; he did so well that he graduated high school 3 years early. In 1937, he received his Bachelor's of Science degree from City College when he was 19. He then went to the University of Rochester to study medicine. His first experience with research was a clinical study he did on jaundice in 1942. Kornberg suffered from mild jaundice himself, and while working as an intern in Strong Memorial Hospital, he became interested in the incidences and symptoms of mild vs. severe jaundice. His clinical study was published and caught the attention of Rolla Dyer, the Director of the National Institutes of Health. Dyer appointed Kornberg to a research post at NIH. From 1942 to 1953, Kornberg was a Commissioned Officer in the U. S. Public Health Service — eventually a Lieutenant in the U. S. Coast Guard. As part of his duties at the NIH, Kornberg did a tour as ship's doctor during World War II. However, he was mostly involved in research on nutrition and metabolic reactions. From 1947-1953, he was the Chief of the Enzyme and Metabolism Section of the NIH and worked at a number of universities as a research investigator. In 1953, Kornberg was appointed head of the Department of Microbiology in the Washington University School of Medicine in St. Louis. It was here that he isolated DNA polymerase I and showed that life (DNA) can be made in a test tube. In 1959, Kornberg shared the Nobel Prize for Physiology or Medicine with Severo Ochoa — Kornberg for the enzymatic synthesis of DNA, Ochoa for the enzymatic synthesis of RNA. In 1959, Kornberg became head of the Department of Biochemistry at Stanford University. He is now Professor Emeritus in the same department at Stanford and still maintains an active research lab. Over the years, Kornberg isolated and identified over one hundred enzymes used in metabolic reactions. Kornberg enjoys teaching and has written a textbook on DNA replication as well as an autobiography on his experiences as a scientist — For the Love of Enzymes. He sees science as a 'creative activity' and an 'art form,' and he derives tremendous satisfaction and enjoyment from doing research. Science runs in the Kornberg family. Kornberg's wife, Sylvy, was a research associate and worked in Kornberg's lab. Kornberg's son, Roger, is also a researcher and isolated DNA polymerase III. | |
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LinksCentrifugationThis page is from the Natural Toxin Research Center at the Texas A&M University. The site explains the physics of centrifugation. Purification by Differential CentrifugationA protocol used in Dr. Donald Slish's laboratory class at the Plattsburgh State University of New York. This college level lab will give you an idea of the types of experiments that can be done using centrifugation and the steps involved. A Lifelong Love Affair With EnzymesA 1989 Opinion article written by Arthur Kornberg for The Scientist. Bibliography
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