Matthew Meselson is an American geneticist and molecular biologist born in 1930. Together with Franklin Stahl, he demonstrated in 1958 the semi-conservative replication mechanism of DNA. He also became an advocate against chemical and biological weapons.
Matthew Meselson(1930 — ?)
Matthew Meselson
États-Unis
5 min read
Frequently asked questions
Key Facts
- Born on May 24, 1930, in Denver, Colorado, in the United States
- Carries out in 1958, with Franklin Stahl, the experiment demonstrating the semi-conservative replication of DNA
- Demonstrates the semi-conservative nature of replication using the heavy isotope nitrogen-15 and ultracentrifugation
- Becomes a professor of biology at Harvard University in 1960
- From the 1960s onward, campaigns against chemical and biological weapons, advising the U.S. government
Works & Achievements
Experimental demonstration that DNA replicates in a semi-conservative way: each new double helix keeps one old strand and one new strand.
Took part in the experiments confirming that messenger RNA carries the information from DNA to the production of proteins.
With Robert Yuan, identification of enzymes able to cut DNA at precise locations — a founding tool of genetic engineering.
Scientific advisory work that influenced the American decision to abandon offensive biological weapons.
Scientific demonstration that the 1979 anthrax outbreak originated from a Soviet military facility, and not from contaminated meat.
Study showing that the alleged toxic weapon in Southeast Asia was in fact made up of bee excrement.
Anecdotes
In 1958, at the California Institute of Technology, Matthew Meselson and Franklin Stahl carried out an experiment so elegant that it came to be nicknamed “the most beautiful experiment in biology.” They fed bacteria with heavy nitrogen, then with normal nitrogen, and using an ultra-fast centrifuge they were able to “weigh” DNA and prove how it copies itself.
Meselson's brilliant idea was to use a cesium salt spinning at tens of thousands of revolutions per minute: the DNA molecules arranged themselves within the tube according to their density, like layers of differing density in a liquid. The visible bands revealed whether the DNA was heavy, light, or half-and-half.
Meselson did not only work in the laboratory: he fought his whole life against chemical and biological weapons. His arguments helped convince American president Richard Nixon to give up the United States' biological weapons in 1969.
In 1979, a mysterious anthrax epidemic in Sverdlovsk, in the USSR, killed dozens of people. The Soviets claimed it was contaminated meat. Meselson investigated for years and demonstrated in 1992 that the spores had escaped from a secret military facility.
In the 1980s, the American government accused the USSR of using a weapon called “yellow rain” in Southeast Asia. Meselson studied the samples and concluded that it was in fact bee droppings that had fallen en masse — a famous example of science calming a political accusation.
Primary Sources
We conclude that the nitrogen of a bacterium's DNA is divided equally between two physically continuous subunits, which remain intact through many generations.
The prospect of considerably enhancing our security by banning biological weapons is one of the rare occasions on which we can genuinely strengthen our safety.
The distribution of cases and prevailing winds points to an airborne source originating from the military facility, and not to food contamination as the Soviet authorities had claimed.
Key Places
American city at the foot of the Rocky Mountains where Matthew Meselson was born in 1930.
Prestigious university where Meselson did his doctoral thesis with Linus Pauling and, together with Stahl, carried out the famous 1958 experiment.
University where Meselson became a professor of molecular biology and pursued his career as a researcher and advocate for disarmament.
Soviet city struck in 1979 by an anthrax outbreak that Meselson investigated on the ground in 1992.
A landmark of molecular biology where DNA researchers gathered and where the ideas of Meselson's era circulated.
Typical Objects
A device spinning at tens of thousands of revolutions per minute that separates molecules according to their density. It is the key instrument of the Meselson-Stahl experiment.
A very dense saline solution that, under centrifugation, forms a density gradient in which DNA arranges itself into bands. It makes it possible to distinguish heavy DNA from light DNA.
The heavy and light variants of the nitrogen atom used as “labels” to mark the DNA of bacteria across generations.
A photographic system measuring the absorption of UV rays to reveal the position of the DNA bands in the centrifuge. It made the invisible visible.
A harmless intestinal bacterium that became the model organism of biologists. Meselson used it to grow the DNA he was going to analyze.
Specimens analyzed by Meselson during his investigation into the Sverdlovsk outbreak. Their study revealed the military origin of the leak.
School Curriculum
Vocabulary & Tags
Key Vocabulary
Tags
Daily Life
Morning
Meselson often began his day at the university, checking the bacterial cultures prepared the day before. Mornings were devoted to the meticulous planning of experiments and to discussions with his students and colleagues.
Afternoon
Afternoons were spent in the laboratory, handling centrifuges, pipettes and tubes, or analyzing the photographs of DNA bands. Part of his time was also given over to meetings of scientific committees on disarmament.
Evening
In the evening, he read scientific papers, wrote his own publications and prepared his classes at Harvard. He also corresponded with policymakers and experts on questions of chemical and biological weapons.
Food
Like a twentieth-century American academic, his diet was ordinary: meals taken on campus, coffees to keep going during the long lab sessions. Nothing exceptional set his table apart from that of his contemporaries.
Clothing
He wore the classic attire of a university professor: shirt, jacket, sometimes a tie. In the laboratory, a white coat protected his clothes from chemicals.
Housing
He lived in the Cambridge area, near Harvard, in the comfort of a second-half-of-the-twentieth-century academic. His true professional “home,” however, remained the laboratory.
Historical Timeline
Period Vocabulary
Liens externes & ressources
Références
Œuvres
Expérience Meselson-Stahl
1958
Mise en évidence de l'ARN messager
1961
Découverte des enzymes de restriction
1968
Plaidoyer pour le renoncement aux armes biologiques
1969
Enquête sur l'épidémie de Sverdlovsk
1992-1994
Analyse de la « pluie jaune »
1983
