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Matthew Stanley Meselson (born May 24, 1930) is a
geneticist A geneticist is a biologist or physician who studies genetics, the science of genes, heredity, and variation of organisms. A geneticist can be employed as a scientist or a lecturer. Geneticists may perform general research on genetic processes ...
and
molecular biologist Molecular biology is the branch of biology that seeks to understand the molecule, molecular basis of biological activity in and between Cell (biology), cells, including biomolecule, biomolecular synthesis, modification, mechanisms, and interact ...
currently at
Harvard University Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of higher le ...
, known for his demonstration, with
Franklin Stahl Franklin (Frank) William Stahl (born October 8, 1929) is an American molecular biologist and geneticist. With Matthew Meselson, Stahl conducted the famous Meselson-Stahl experiment showing that DNA is replicated by a semiconservative mechanism, ...
, of semi-conservative
DNA replication In molecular biology, DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. DNA replication occurs in all living organisms acting as the most essential part for biological inheritanc ...
. After completing his Ph.D. under Linus Pauling at the
California Institute of Technology The California Institute of Technology (branded as Caltech or CIT)The university itself only spells its short form as "Caltech"; the institution considers other spellings such a"Cal Tech" and "CalTech" incorrect. The institute is also occasional ...
, Meselson became a Professor at Harvard University in 1960, where he has remained, today, as Thomas Dudley Cabot Professor of the Natural Sciences. In the famous Meselson–Stahl experiment of 1958 he and
Frank Stahl Franklin (Frank) William Stahl (born October 8, 1929) is an American molecular biologist and geneticist. With Matthew Meselson, Stahl conducted the famous Meselson-Stahl experiment showing that DNA is replicated by a semiconservative mechanism, ...
demonstrated through nitrogen
isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numb ...
labeling that DNA is replicated semi-conservatively. In addition, Meselson,
François Jacob François Jacob (17 June 1920 – 19 April 2013) was a French biologist who, together with Jacques Monod, originated the idea that control of enzyme levels in all cells occurs through regulation of transcription. He shared the 1965 Nobel Prize ...
, and
Sydney Brenner Sydney Brenner (13 January 1927 – 5 April 2019) was a South African biologist. In 2002, he shared the Nobel Prize in Physiology or Medicine with H. Robert Horvitz and Sir John E. Sulston. Brenner made significant contributions to work ...
discovered the existence of
messenger RNA In molecular biology, messenger ribonucleic acid (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a gene, and is read by a ribosome in the process of synthesizing a protein. mRNA is created during the p ...
in 1961. Meselson has investigated DNA repair in cells and how cells recognize and destroy foreign DNA, and, with
Werner Arber Werner Arber (born 3 June 1929 in Gränichen, Aargau) is a Swiss microbiologist and geneticist. Along with American researchers Hamilton Smith and Daniel Nathans, Werner Arber shared the 1978 Nobel Prize in Physiology or Medicine for the dis ...
, was responsible for the discovery of
restriction enzymes A restriction enzyme, restriction endonuclease, REase, ENase or'' restrictase '' is an enzyme that cleaves DNA into fragments at or near specific recognition sites within molecules known as restriction sites. Restriction enzymes are one class o ...
. Since 1963 he has been interested in chemical and biological defense and arms control, has served as a consultant on this subject to various government agencies. Meselson worked with
Henry Kissinger Henry Alfred Kissinger (; ; born Heinz Alfred Kissinger, May 27, 1923) is a German-born American politician, diplomat, and geopolitical consultant who served as United States Secretary of State and National Security Advisor under the presid ...
under the Nixon administration to convince President
Richard Nixon Richard Milhous Nixon (January 9, 1913April 22, 1994) was the 37th president of the United States, serving from 1969 to 1974. A member of the Republican Party, he previously served as a representative and senator from California and was ...
to renounce biological weapons, suspend chemical weapons production, and support an international treaty prohibiting the acquisition of biological agents for hostile purposes, which in 1972 became known as the
Biological Weapons Convention The Biological Weapons Convention (BWC), or Biological and Toxin Weapons Convention (BTWC), is a disarmament treaty that effectively bans biological and toxin weapons by prohibiting their development, production, acquisition, transfer, stockpil ...
. Meselson has received the Award in Molecular Biology from the National Academy of Sciences, the Public Service Award of the Federation of American Scientists, the Presidential Award of the
New York Academy of Sciences The New York Academy of Sciences (originally the Lyceum of Natural History) was founded in January 1817 as the Lyceum of Natural History. It is the fourth oldest scientific society in the United States. An independent, nonprofit organization wi ...
, the 1995
Thomas Hunt Morgan Medal The Thomas Hunt Morgan Medal is awarded by the Genetics Society of America (GSA) for lifetime contributions to the field of genetics. The medal is named after Thomas Hunt Morgan, the 1933 Nobel Prize winner, who received this award for his work wi ...
of the Genetics Society of America, as well as the
Lasker Award The Lasker Awards have been awarded annually since 1945 to living persons who have made major contributions to medical science or who have performed public service on behalf of medicine. They are administered by the Lasker Foundation, which was ...
for Special Achievement in Medical Science. His laboratory at Harvard currently investigates the biological and evolutionary nature of sexual reproduction, genetic recombination, and aging. Many of his past students are notable biologists, including Nobel Laureate
Sidney Altman Sidney Altman (May 7, 1939 – April 5, 2022) was a Canadian-American molecular biologist, who was the Sterling Professor of Molecular, Cellular, and Developmental Biology and Chemistry at Yale University. In 1989, he shared the Nobel Prize in ...
, as well as
Mark Ptashne Mark Ptashne (born June 5, 1940, in Chicago) is a molecular biologist. He is the Ludwig Chair of Molecular Biology at Memorial Sloan–Kettering Cancer Center in New York City. Ptashne grew up in Chicago. He earned his undergraduate degree at Re ...
,
Susan Lindquist Susan Lee Lindquist, ForMemRS (June 5, 1949 – October 27, 2016) was an American professor of biology at MIT specializing in molecular biology, particularly the protein folding problem within a family of molecules known as heat-shock proteins ...
, Stephen F. Heinemann, and Richard I. Morimoto.


Early life and education

Meselson was born in Denver, Colorado, on May 24, 1930, and attended elementary and high-school in Los Angeles, California. While a young child he was interested in chemistry and physics, and conducted many experiments in the natural sciences at home. During
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
, Meselson attended summer school during summer vacations and received enough high school credits to graduate a year and a half ahead of time. When he attempted to acquire his diploma from the registrar at his high school, however, he was informed that in order to receive his high school diploma, he needed three full years of physical education, which he lacked. After searching for options, he enrolled at the
University of Chicago The University of Chicago (UChicago, Chicago, U of C, or UChi) is a private research university in Chicago, Illinois. Its main campus is located in Chicago's Hyde Park neighborhood. The University of Chicago is consistently ranked among the b ...
at the age of 16 in 1946 intending to study chemistry, since it did not require a high school diploma to attend.


Higher education

At the
University of Chicago The University of Chicago (UChicago, Chicago, U of C, or UChi) is a private research university in Chicago, Illinois. Its main campus is located in Chicago's Hyde Park neighborhood. The University of Chicago is consistently ranked among the b ...
, Meselson studied liberal arts including history and classics as an undergraduate from 1946 to 1949 after realizing upon arriving that the university had abolished bachelor's degrees in specialized field such as chemistry and physics. After completing his studies, Meselson spent half a year traveling in Europe. where he spend most of his time reading and making friends. The devastation of the war was still evident in Europe in 1949, as were the beginning tensions of the
Cold War The Cold War is a term commonly used to refer to a period of geopolitical tension between the United States and the Soviet Union and their respective allies, the Western Bloc and the Eastern Bloc. The term '' cold war'' is used because the ...
. The following year, Meselson returned to Caltech to begin freshman studies again, but disliked the pedagogical approach in most of the courses he took. He enrolled, however, in Linus Pauling's freshman chemistry course, which he loved, and worked on a project for Pauling the same year on
hemoglobin Hemoglobin (haemoglobin BrE) (from the Greek word αἷμα, ''haîma'' 'blood' + Latin ''globus'' 'ball, sphere' + ''-in'') (), abbreviated Hb or Hgb, is the iron-containing oxygen-transport metalloprotein present in red blood cells (erythrocyt ...
structure. Meselson subsequently returned to the University of Chicago for a year to enroll in courses in chemistry, physics, and math, though he did not receive another degree. The following year, he was accepted into a graduate physics program at the
University of California at Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant uni ...
where he remained for a year. In the summer of 1953, Meselson was at a swimming pool party at the Pauling home in
Sierra Madre Sierra Madre (Spanish, 'mother mountain range') may refer to: Places and mountains Mexico *Sierra Madre Occidental, a mountain range in northwestern Mexico and southern Arizona *Sierra Madre Oriental, a mountain range in northeastern Mexico *S ...
(he was friends with Pauling's son Peter and with his daughter Linda), and Pauling asked him what he intended to do the following year. Upon hearing Meselson respond that he intended to return to the
University of Chicago The University of Chicago (UChicago, Chicago, U of C, or UChi) is a private research university in Chicago, Illinois. Its main campus is located in Chicago's Hyde Park neighborhood. The University of Chicago is consistently ranked among the b ...
, Pauling immediately asked him to come to Caltech to begin graduate studies with him, to which Meselson agreed. As a graduate student of Linus Pauling in chemistry at the California Institute of Technology (1953-1957), Meselson's doctoral dissertation was on equilibrium density gradient centrifugation and on
x-ray crystallography X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles ...
. He was Assistant Professor of Physical Chemistry and then Senior Research Fellow at Caltech until he joined the Harvard faculty in 1960.


Research

In 1957, Meselson and
Franklin Stahl Franklin (Frank) William Stahl (born October 8, 1929) is an American molecular biologist and geneticist. With Matthew Meselson, Stahl conducted the famous Meselson-Stahl experiment showing that DNA is replicated by a semiconservative mechanism, ...
(as part of the phage group) showed that DNA replicates semi-conservatively. In order to test hypotheses for how DNA replicates, Meselson and Stahl, together with Jerome Vinograd, invented a method that separates macromolecules according to their buoyant density. The method, equilibrium density gradient centrifugation, was sufficiently sensitive that Meselson and Stahl were able to separate DNA containing the heavy isotope of nitrogen, 15N, from DNA made of the lighter isotope, 14N. In their classic experiment, described and analyzed in a book by science historian Frederic L. Holmes, they grew the bacterium ''Escherichia coli'' for many generations in medium containing 15N as the only nitrogen source and then switched the bacteria to growth medium containing 14N instead. They extracted DNA from bacteria prior to switching and, at intervals, for several generations thereafter. After one generation of growth, all the DNA was seen to have a density halfway between that of 15N DNA and 14N DNA. In successive generations, the fraction of DNA that was "half-heavy" fell by a factor of ½, as the total amount of DNA increased two-fold. When the half-heavy DNA was made single stranded by heating, it separated into two density species, one heavy (containing only 15N) and one light (containing only 14N). The experiment implied that, upon replication, the two complementary strands of the bacterial DNA separate, and that each of the single strands directs the synthesis of a new, complementary strand, a result that verified the suggestion for DNA replication put forward five years earlier by James Watson and Francis Crick and lent important early support for the Watson-Crick model of the DNA molecule. In collaboration with
Jean Weigle Jean-Jacques Weigle (9 July 1901 – 28 December 1968) was a Swiss molecular biologist at Caltech and formerly a physicist at the University of Geneva from 1931 to 1948. He is known for his major contributions on field of bacteriophage λ research, ...
, Meselson then applied the density gradient method to studies of genetic recombination in the bacteriophage Lambda. The question was whether such recombination involved breakage of the recombining DNA molecules or cooperative synthesis of new molecules. The question could be answered by examining phage particles derived from co-infection of bacteria with genetically marked Lambda phages that were labeled with heavy isotopes (13C and 15N). The density-gradient method allowed individual progeny phages to be characterized for their inheritance of parental DNA and of parental genetic makers. Meselson's initial demonstration of breakage-associated, replication-independent recombination was later found to reflect the activity of a special system that can recombine Lambda DNA at only one spot, normally used by the phage to insert itself into the chromosome of a host cell. Subsequently, variations of the experiment by Franklin Stahl revealed reciprocal dependencies between DNA replication and most genetic recombination. With Charles Radding, Meselson developed a model for recombination between DNA duplexes that guided research in the field for the decade from 1973 to 1983. In 1961,
Sydney Brenner Sydney Brenner (13 January 1927 – 5 April 2019) was a South African biologist. In 2002, he shared the Nobel Prize in Physiology or Medicine with H. Robert Horvitz and Sir John E. Sulston. Brenner made significant contributions to work ...
,
François Jacob François Jacob (17 June 1920 – 19 April 2013) was a French biologist who, together with Jacques Monod, originated the idea that control of enzyme levels in all cells occurs through regulation of transcription. He shared the 1965 Nobel Prize ...
and Meselson used the density-gradient method to demonstrate the existence of messenger RNA. In subsequent work, Meselson and his students demonstrated the enzymatic basis of host-directed restriction, a process by which cells recognize and destroy foreign DNA and then predicted and demonstrated methyl-directed mismatch repair, a process that enables cells to correct mistakes in replicating DNA. Meselson's current research is aimed at understanding the advantage of sexual reproduction in evolution. Meselson and his colleagues have recently demonstrated that Bdelloid rotifers do, in fact, engage in sexual reproduction employing meiosis of an atypical sort.


Meselson effect

When two
alleles An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution. ::"The chrom ...
, or copies of a gene, within an asexual diploid individual evolve independently of each other, they become increasingly different over time. This phenomenon of allelic divergence was first described by William Birky, but is more commonly known as the Meselson effect. In sexual organisms, the processes of recombination and independent assortment allow both of the alleles within an individual to descend from a recent single ancestral allele. Without recombination or independent assortment, alleles cannot descend from a recent ancestral allele. Instead the alleles share a last common allelic ancestor at or just preceding the loss of meiotic recombination. A striking example of this effect was described in
bdelloid rotifers Bdelloidea (Greek ''βδέλλα'', ''bdella'', "leech") is a class of rotifers found in freshwater habitats all over the world. There are over 450 described species of bdelloid rotifers (or 'bdelloids'), distinguished from each other mainl ...
, in which the two alleles of the ''lea''
gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
have diverged into two different genes which work together to preserve the organism during periods of
dehydration In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mil ...
. The Meselson effect should cause entire copies of an organism's genome to diverge from each other, effectively reducing all anciently asexual organisms to a haploid state, in a process similar to the diploidization following
whole genome duplication Paleopolyploidy is the result of genome duplications which occurred at least several million years ago (MYA). Such an event could either double the genome of a single species (autopolyploidy) or combine those of two species (allopolyploidy). Bec ...
. However,
gene conversion Gene conversion is the process by which one DNA sequence replaces a homologous sequence such that the sequences become identical after the conversion event. Gene conversion can be either allelic, meaning that one allele of the same gene replaces a ...
, a form of recombination common in asexual organisms, may prevent the Meselson effect from occurring in young asexual organisms and may limit the effect in Bdelloid rotifers. Moreover, a number of putative examples of the Meselson effect remain controversial because other biological process, such as hybridation, can mimic the Meselson effect.


Chemical and biological weapons defense and disarmament

In 1963 Meselson served as a resident consultant in the US Arms Control and Disarmament Agency, where he became interested in chemical and biological weapons programs and policies. Since then he has been involved in chemical and biological weapons defense and disarmament matters as a consultant to various US government agencies and through the
Harvard Sussex Program Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of higher le ...
, an academic research organization based at Harvard and at the University of Sussex in the UK of which he and Julian Perry Robinson in the UK are co-directors. Concluding that biological weapons served no substantial military purpose for the US and that their proliferation would pose a serious threat and that, in years ahead, the exploitation of advanced biology for hostile purposes would be inimical to society generally, he worked to persuade members of the Executive Branch, the Congress and the public that the US had no need for such weapons and that there would be benefits in renouncing them and working for worldwide prohibition. After President
Richard Nixon Richard Milhous Nixon (January 9, 1913April 22, 1994) was the 37th president of the United States, serving from 1969 to 1974. A member of the Republican Party, he previously served as a representative and senator from California and was ...
in 1969 canceled the US BW offensive program and endorsed a UK proposal for an international ban, Meselson was among those who successfully advocated international agreements to ban biological and then chemical weapons, leading to the
Biological Weapons Convention The Biological Weapons Convention (BWC), or Biological and Toxin Weapons Convention (BTWC), is a disarmament treaty that effectively bans biological and toxin weapons by prohibiting their development, production, acquisition, transfer, stockpil ...
of 1972 and the Chemical Weapons Convention of 1993. Meselson and his colleagues have undertaken three on-site investigations with implications for chemical and biological weapons arms control. During August and September 1970, on behalf of the American Association for the Advancement of Science, Meselson led a team in the Republic of Vietnam in a pilot study of the ecological and health effects of the military use of herbicides. Upon returning to Harvard, he and Robert Baughman developed an advanced mass-spectrometric method for analysis of the toxic herbicide contaminant dioxin and applied it to environmental and biomedical samples from the Vietnam and the US. In December 1970, President Richard Nixon ordered a "rapid but orderly" phase-out of herbicide operations in Vietnam. During the 1980s, Meselson investigated allegations that "
yellow rain Yellow rain was a 1981 political incident in which the United States Secretary of State Alexander Haig accused the Soviet Union of supplying T-2 mycotoxin to the Communist states in Vietnam, Laos and Cambodia for use in counterinsurgency warfare. ...
" was a Soviet toxin weapon being used against Hmong tribespeople in Laos. Citing the physical appearance and high pollen content of samples of the alleged agent; the resemblance of the alleged attacks to showers of feces from swarms of honeybees that he and entomologist Thomas Seeley documented during a 1983 field study in Thailand; the inability of US and UK government laboratories to corroborate initial reports of the presence of trichothecene mycotoxins in samples of the alleged agent and in biomedical samples from alleged victims; the lack of any supporting evidence from extensive interviews with Vietnamese military defectors and prisoners; and other considerations, Meselson and his colleagues argued that the allegations were mistaken. In April 1980 Meselson served as a resident consultant to the CIA investigating a major outbreak of anthrax among people in the Soviet city of Sverdlovsk. He concluded that on the basis of available evidence the official Soviet explanation that the outbreak was caused by consumption of meat from infected cattle was plausible but that there should be an independent on-site investigation. After the collapse of the Soviet Union, he was allowed to bring a team to Sverdlovsk in 1992 and again in 1993. Their reports conclusively showed that the official Soviet explanation was wrong and that the outbreak was caused by the release of an anthrax aerosol at a military biological facility in the city. Meselson is a member of the U.S. National Academy of Sciences, the American Academy of Arts and Sciences, the American Philosophical Society, the Académie des Sciences (Paris), the Royal Society (London) and the Russian Academy of Sciences and has received numerous awards and honors in the field of science and in public affairs. He has served on the Council of the National Academy of Sciences, the Council of the Smithsonian Institution, the Arms Control and Non-Proliferation Advisory Board to the US Secretary of State and the Committee on International Security and Arms Control of the US National Academy of Sciences. He is past President of the Federation of American Scientists, and presently is co-director of the Harvard Sussex Program on Chemical and Biological Weapons and a member of the Board of Directors of the Belfer Center for Science and International Affairs at the John F. Kennedy School of Government at Harvard University.


Selected awards

*1963 US National Academy of Sciences Prize for Molecular Biology *1964 Eli Lilly Award in Microbiology or Immunology *1966 Guggenheim Fellowship *1971 Alumni Medal, University of Chicago Alumni Association *1972 Public Service Award, Federation of American Scientists *1975 Alumni Distinguished Service Award, California Institute of Technology *1975 Lehman Award, New York Academy of Sciences *1978 Leo Szilard Award, American Physical Society *1983 Presidential Award, New York Academy of Sciences *1984 MacArthur Fellows Program Fellowship *1990 Scientific Freedom and Responsibility Award,
American Association for the Advancement of Science The American Association for the Advancement of Science (AAAS) is an American international non-profit organization with the stated goals of promoting cooperation among scientists, defending scientific freedom, encouraging scientific respons ...
*1995 Genetics Society of America -
Thomas Hunt Morgan Medal The Thomas Hunt Morgan Medal is awarded by the Genetics Society of America (GSA) for lifetime contributions to the field of genetics. The medal is named after Thomas Hunt Morgan, the 1933 Nobel Prize winner, who received this award for his work wi ...
for lifetime contributions *2002 Public Service Award,
American Society for Cell Biology The American Society for Cell Biology (ASCB) is a professional society that was founded in 1960.Lasker Award The Lasker Awards have been awarded annually since 1945 to living persons who have made major contributions to medical science or who have performed public service on behalf of medicine. They are administered by the Lasker Foundation, which was ...
for Special Achievement in Medical Science *2005 Life Member of the New York Academy of Sciences. *2008 Mendel Medal of the UK Genetics Society. *2019 Future of Life Award for helping ban bioweapons.


Honorary doctoral degrees

*1966 Oakland University *1971 Columbia University *1975 University of Chicago *1987 Yale University *1988 Princeton University *2003 Northwestern University *2013 McGill University *2017 Rockefeller University


Personal life

He married three times, first to Katherine Kaynis, then to Sarah Page, with whom he had two daughters, Amy and Zoe. His third marriage was to Jeanne Guillemin, with whom he shares two stepsons."Obituaries: Amy Meselson, 46, Immigrant Defender," The New York Times, August 8, 2018


References


External links


Diplomacy Light Podcast #3 BWC at Fifty: Matthew Meselson, John Walker, and Sergey BatsonovXapiens Podcast Ending Biological Warfare, COVID, Henry Kissinger, mRNA, Meselson-Stahl, Mathew MeselsonMatthew Meselson's bio at Harvard Kennedy School
* ttps://www.ibiology.org/genetics-and-gene-regulation/semi-conservative-replication/ iBio The Semi-Conservative Replication of DNAbr>McGill Honorary Doctorate Address 2013Conversations in Genetics Interview 2016
{{DEFAULTSORT:Meselson, Matthew Stanley 1930 births Living people Jewish American scientists American geneticists MacArthur Fellows Foreign Members of the Royal Society History of genetics 21st-century American biologists University of Chicago alumni Harvard University faculty Members of the French Academy of Sciences Foreign Members of the Russian Academy of Sciences Members of the United States National Academy of Sciences Members of the American Philosophical Society Fellows of the American Association for the Advancement of Science Members of the National Academy of Medicine 21st-century American Jews California Institute of Technology fellows