Matthew Stanley Meselson (born May 24, 1930) is an American
geneticistA geneticist is a scientist who studies genetics, the science of heredity and variation of organisms. A geneticist can be employed as a researcher or lecturer...
and molecular biologist whose research was important in showing how
DNA replicatesDNA replication, the basis for biological inheritance, is a fundamental process occurring in all living organisms to copy their DNA. This process is "semiconservative" in that each strand of the original double-stranded DNA molecule serves as template for the reproduction of the complementary strand...
,
recombinesGenetic recombination is the process by which a strand of genetic material is broken and then joined to a different DNA molecule. In eukaryotes recombination occurs in mitosis as a common mechanism of DNA repair and in meiosis as a way of facilitating chromosomal crossover...
and is
repairedDNA repair refers to a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolic activities and environmental factors such as UV light and Radiation can cause DNA damage, resulting in as many as 1...
in cells. In his mature years, he has been an active chemical and biological weapons activist and consultant. He is married to the medical anthropologist and biological weapons writer
Jeanne GuilleminJeanne Harley Guillemin is a medical anthropologist, a Professor of Sociology at Boston College and a senior fellow in the Security Studies Program at Massachusetts Institute of Technology. She is also co-head of the National Library of Medicine's HealthAware Project at Brigham and Women's...
.
He began studying chemistry and graduated from the
University of ChicagoThe University of Chicago is a private, coeducational research university in Chicago, Illinois, USA. It was founded by oil magnate and benefactor John D...
in 1951.
Matthew Stanley Meselson (born May 24, 1930) is an American
geneticistA geneticist is a scientist who studies genetics, the science of heredity and variation of organisms. A geneticist can be employed as a researcher or lecturer...
and molecular biologist whose research was important in showing how
DNA replicatesDNA replication, the basis for biological inheritance, is a fundamental process occurring in all living organisms to copy their DNA. This process is "semiconservative" in that each strand of the original double-stranded DNA molecule serves as template for the reproduction of the complementary strand...
,
recombinesGenetic recombination is the process by which a strand of genetic material is broken and then joined to a different DNA molecule. In eukaryotes recombination occurs in mitosis as a common mechanism of DNA repair and in meiosis as a way of facilitating chromosomal crossover...
and is
repairedDNA repair refers to a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolic activities and environmental factors such as UV light and Radiation can cause DNA damage, resulting in as many as 1...
in cells. In his mature years, he has been an active chemical and biological weapons activist and consultant. He is married to the medical anthropologist and biological weapons writer
Jeanne GuilleminJeanne Harley Guillemin is a medical anthropologist, a Professor of Sociology at Boston College and a senior fellow in the Security Studies Program at Massachusetts Institute of Technology. She is also co-head of the National Library of Medicine's HealthAware Project at Brigham and Women's...
.
Youth and education
He began studying chemistry and graduated from the
University of ChicagoThe University of Chicago is a private, coeducational research university in Chicago, Illinois, USA. It was founded by oil magnate and benefactor John D...
in 1951. He went on to study under
Linus PaulingLinus Carl Pauling was an American chemist, peace activist, author, and educator. He was one of the most influential chemists in history and ranks among the most important scientists in any field of the 20th century. Pauling was among the first scientists to work in the fields of quantum...
who assigned him work on
x-ray crystallographyX-ray crystallography is a method of determining the arrangement of atoms within a crystal, in which a beam of X-rays strikes a crystal and diffracts into many specific directions. From the angles and intensities of these diffracted beams, a crystallographer can produce a three-dimensional picture...
which he later wrote a thesis on in 1958. He was a research fellow and then Assistant Professor of Physical Chemistry at CalTech until he joined the Harvard faculty in 1960, where he conducts research in molecular genetics and evolution. He started in
HarvardHarvard University is a private university located in Cambridge, Massachusetts and a member of the Ivy League. Founded in 1636 by the colonial Massachusetts legislature, Harvard is the oldest institution of higher learning in the United States and currently comprises ten separate academic units...
as associate professor and taught undergraduate
geneticsGenetics, , a discipline of biology, is the science of heredity and variation in living organisms. The fact that living things inherit traits from their parents has been used since prehistoric times to improve crop plants and animals through selective breeding...
for many years.
DNA breakthroughs
In 1957 with
Franklin StahlDr. Franklin William Stahl is an American molecular biologist. With Matthew Meselson, Stahl conducted the famous Meselson-Stahl experiment showing that DNA is replicated by a semiconservative mechanism, meaning that each strand of the DNA serves as a template for the "replicated" strand.He is...
he showed that DNA replicates semi-conservatively. The
Meselson-Stahl experimentThe Meselson-Stahl experiment was an experiment by Matthew Meselson and Franklin Stahl which demonstrated that DNA replication was semiconservative...
used the
Escherichia coliEscherichia coli , is a Gram negative bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E...
grown in the presence of the
nitrogenNitrogen is a chemical element that has the symbol N and atomic number 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78% by volume of Earth's atmosphere.Many industrially important...
isotopeIsotopes are different types of atoms of the same chemical element, each having a different number of neutrons. Correspondingly, isotopes differ in mass number but not in atomic number. The difference in the number of nucleons comes from a difference how many neutrons are in the atomic nucleus...
nitrogen-15, which was then switched to be grown with normal nitrogen, nitrogen-14. When they extracted the DNA using density centrifugation they found three types of DNA, one containing nitrogen-15, one containing nitrogen-14, and a hybrid containing both isotopes. When the hybrid DNA was made single stranded by heating, they could show one parental strand and one that had been newly synthesised, so when DNA is synthesised the DNA double helix splits into two, each of the single strands acting as a template for the synthesis of a complementary strand. This phenomenon is called semi-conservative DNA replication.
He showed in the years that followed many more theories in relation to this with the help of Jean Weigle. In 1961 with Frank Stahl, Sidney Brenner and
François JacobFrançois Jacob is a French biologist who, together with Jacques Monod, originated the idea that control of enzyme levels in all cells occurs through feedback on transcription. He shared the 1965 Nobel Prize in Medicine with Jacques Monod and André Lwoff.-Childhood and education:François Jacob is...
he later demonstrated that
ribosomal RNARibosomal RNA is the central component of the ribosome, the protein manufacturing machinery of all living cells. The function of the rRNA is to provide a mechanism for decoding mRNA into amino acids and to interact with the tRNAs during translation by providing peptidyl transferase activity.The...
molecules are stable, which later proved the existence of mRNA - a problem scientists had struggled with previously. He later showed with Charles Radding that genetic
recombinationRecombination may refer to:* Genetic recombination, the process by which genetic material is broken and joined to other genetic material* Carrier generation and recombination, processes by which mobile electrons and electron holes are created and eliminated...
results from the splicing of DNA molecules. He also demonstrated the enzymatic basis of a process by which cells recognize and destroy foreign DNA, and discovered methyl-directed mismatch repair, which enables cells to repair mistakes in DNA.
The Meselson effect
The
Meselson laboratory studies the evolution of
asexualityAsexual reproduction is reproduction which does not involve meiosis, ploidy reduction, or fertilization. Only one parent is involved in asexual reproduction. A more stringent definition is agamogenesis which refers to reproduction without the fusion of gametes...
in bdelloid rotifers. Meselson described the "Meselson effect", in which two alleles in an asexual organism evolve independently and divergently over time, producing what is essentially two genomes in one organism. This is due to the lack of sexual recombination which shuffles genes between alleles during
meiosisIn biology, meiosis is a process of reductional division in which the number of chromosomes per cell is cut in half. In animals, meiosis always results in the formation of gametes, while in other organisms it can give rise to spores. As with mitosis, before meiosis begins, the DNA in the original...
. Meselson's laboratory provided exciting evidence that this is indeed the case in asexual bdelloid rotifers, and the Meselson effect was subsequently used to explain how bdelloid rotifers deal with dehydration. Dr. Alan Tunnacliffe's Cambridge lab showed that the
lea geneA gene is the basic unit of heredity in a living organism. All living things depend on genes. Genes hold the information to build and maintain their cells and pass genetic traits to offspring...
had diverged through the Meselson effect into two different genes whose
proteinProteins are organic compounds made of amino acids arranged in a linear chain and folded into a globular form. The amino acids in a polymer chain are joined together by the peptide bonds between the carboxyl and amino groups of adjacent amino acid residues...
products work in
synergySynergy is the term used to describe a situation where different entities cooperate advantageously for a final outcome. Simply defined, it means that the whole is greater than the sum of the individual parts. Although the whole will be greater than each individual part, this is not the concept of...
to preserve the organism during periods of
dehydrationDehydration is defined as excessive loss of body water. It is literally the removal of water from an object. In physiological terms, it entails a relative deficiency of water molecules in relation to other dissolved solutes...
, suggesting that the Meselson effect is a mechanism of generating
variationGenetic diversity is a level of biodiversity that refers to the total number of genetic characteristics in the genetic makeup of a species. It is distinguished from genetic variability, which describes the tendency of genetic characteristics to vary....
that confers
evolutionary advantageIn biology, evolution is change in the genetic material of a population of organisms from one generation to the next. Though changes produced in any one generation are normally small, differences accumulate with each generation and can, over time, cause substantial changes in the population, a...
.
Chemical and biological weapons disarmament activism
In 1963 Meselson served as a resident consultant in the US
Arms Control and Disarmament AgencyThe U.S. Arms Control and Disarmament Agency was established as an independent agency of the United States government by the Arms Control and Disarmament Act , September 26, 1961, a bill drafted by presidential adviser John J. McCloy. Its predecessor was the U.S. Disarmament Administration, part...
, since then he has been involved in chemical and biological weapons
disarmamentDisarmament is the act of reducing, limiting, or abolishing weapons. Disarmament generally refers to a country's military or specific type of weaponry. The most common form of disarmament is abolishment of weapons of mass destruction, such as nuclear arms...
policy formation as a consultant and through the
Harvard Sussex Program, a disarmament think-tank.
- Meselson was a leader in a 1980s effort attempting to show that "Yellow Rain
T-2 is a trichothecene mycotoxin, is a naturally-occurring mold byproduct of Fusarium spp fungus which is toxic to humans and animals. The clinical condition it causes is alimentary toxic aleukia and a host of symptoms related to organs as diverse as the skin, airway, and stomach...
" was not a Soviet biological warfare agent (as claimed by the CIA and the State Department), but bee droppings, a controversy that remains unresolved.
- In 1992-94, Meselson investigated and reported on the Sverdlovsk anthrax leak
The Sverdlovsk anthrax leak is an incident when spores of anthrax were accidentally released from a military facility in the city of Sverdlovsk 1450 km east of Moscow on April 2, 1979. This accident is sometimes called "biological Chernobyl"...
, a 1979 bio-warfare mishap in the Soviet UnionThe Union of Soviet Socialist Republics was a constitutionally socialist state that existed in Eurasia from 1922 to 1991. The name is a translation of the , tr. Soyuz Sovetskikh Sotsialisticheskikh Respublik, abbreviated СССР, SSSR. The common short name is Soviet Union, from , Sovetskiy Soyuz...
that resulted in the deaths of 64 persons. Despite his earlier efforts to demonstrate the "innocent" nature of the accident, Meselson's investigation incontrovertably proved that the Soviets had a secret bio-weapons program in violation of the Biological Weapons ConventionThe Convention on the Prohibition of the Development, Production and Stockpiling of Bacteriological and Toxin Weapons and on their Destruction was the first multilateral disarmament treaty banning the...
.
Selected Awards
- 1975 Caltech Distinguished Alumni Award.
- 1995 Genetics Society of America - Thomas Hunt Morgan Medal for lifetime contributions.
- 2002 American Society for Cell Biology’s Public Service Award for Advancing Prevention of Chemical and Biological Weapons.
- 2004 Lasker Award for Special Achievement in Medical Science. The prize honors a lifetime of solving fundamental biological problems.
- 2005 Election as Honorary Life Member to the National Academy of Sciences.
- 2008 Mendel Medal of the UK Genetics Society.
External links