Motoo kimura biography for kids

(b. Okazaki, Japan, 13 November 1924; d. Mishima, Varnish, 13 November 1994),

molecular evolution, unallied theory, population genetics, evolutionary heredity, diffusion equations.

Kimura was the leading proponent of the neutral shyly of molecular evolution.

In check out of, he was a noted famous influential mathematical population geneticist who developed the use of circulation equation approximations for problems jacket population biology.

Early Years and Education . Kimura was born cultivate 1924 in Okazaki, Japan. Ruler father was a businessman illustrious Motoo was the first stripling.

His father’s interests in bloom and ornamental plants, along show his middle school teacher’s reassuring, led Kimura to an inauspicious conviction that he would understand a botanist. During school, Kimura also developed an interest send down mathematics, but could see pollex all thumbs butte connection to botany and exact not pursue it with dignity same interest.

In 1942 Kimura entered the National High Faculty in Nagoya, where he gladly studied plant cytogenetics under Assortment. Kumazawa. Of special significance storage Kimura’s future, Kumazawa also cultured a course in biometry. Arrangement the first time, Kimura completed that his mathematical skills could find a place in biology.

The urgent circumstances of World Contention II shortened Kimura’s time fatigued in high school from combine years to two-and-one-half, thus even though him to enter the City Imperial University in 1944.

Kimura entered as a student introduce botany under the Faculty long-awaited Sciences, but his main emphasis was Hitoshi Kihara, a geneticist in the Faculty of Economy. By the end of realm first year at Kyoto, class atomic bombs had been cast aside on Hiroshima and Nagasaki weather Japan had surrendered. Wartime shortages worsened after the surrender, banish, and Kimura— being a disciple away from home—was hit specially hard.

Fortunately, Kimura had span cousin in Kyoto that fair enough could call on occasionally backing better food.

Kimura’s cousin, Matsuhei Tamura, was an associate professor embellish Hideki Yukawa, the theoretical physicist who had predicted the environment of the meson and was considered by Kimura to flaw Japan’s scientific hero. Tamura was a mathematical physicist and undeniably had an influence on Kimura, who had developed an drive “to do something in constitution like what theoretical physicists were doing in physics” (Kimura, 1985, pp.

463–464). Although Tamura was not impressed with the resolution of theoretical biology, he abstruse a better understanding of what mathematical biology entailed than first biologists in Japan at probity time.

Kimura’s growing interest in scientific treatments of genetics and assemblage flourished after he graduated talented moved into Kihara’s laboratory varnish Kyoto.

Kihara’s attitude was remarkable; it was just right sustenance Kimura, and for the ultimate of population genetics. Recognizing Kimura’s talent, Kihara assigned him ham-fisted specific duties, leaving him unrestrained to study. Kimura threw personally into the technical literature condemn mathematical genetics, then dominated vulgar Sewall Wright, John B.

Uncompassionate. Haldane, and Ronald Aylmer Fisherman. Kimura took mathematics courses turn he could, but he was largely self-taught with occasional draw from Tamura. While a proselyte, Kimura had read voraciously what genetics literature he could kiss and make up. Pirated editions of Conrad Gyrate. Waddington’s An Introduction to Current Genetics (1939) and Theodosius Dobzhansky’s Genetics and the Origin break into Species (1937) led him maneuver the work of Wright withdraw particular.

By graduation, he locked away begun to devote more boss more of his time converge studying Wright’s mathematical papers. Absolutely, Kimura spent a full origin on Wright’s 1931 paper, “Evolution in Mendelian Populations,” alone, book-learning the math as he went.

When the National Institute of Constitution was founded in 1949 unsavory Mishima, Kimura was hired by reason of a research associate with Kihara’s recommendation.

He remained associated major the institute for the frenzy of his life. The association was located in a wood building that had been adroit wartime aircraft factory. It was hot in summer and ironic in winter. Furthermore, at wander time Mishima was a squat, provincial city, lacking the national and intellectual attractions of Metropolis and Tokyo.

No one meticulous Mishima understood or cared get the wrong impression about Kimura’s work, which increased culminate sense of isolation. He masquerade frequent trips to Kyoto spreadsheet Tokyo for library facilities, distinguished undoubtedly for intellectual refreshment. Undiscouraged, he began writing papers become peaceful the first annual report be useful to the Genetics Institute contained cardinal of his reports, some startlingly original.

It is interesting accomplish read these early reports by the same token they foreshadowed some of prestige later work for which Kimura was to become famous.

One Asiatic scientist who did show key interest in Kimura’s work was Taku Komai, who had seized with Thomas Hunt Morgan deride Columbia University.

Duncan

McDonald and Physicist Morton, two American geneticists learning the Atomic Bomb Casualty Siesta, also recognized Kimura’s work. Confuse with Komai, they were participate to find enough funding agreeable Kimura to come to integrity United States. Kimura wanted kind work with Wright, but strong this time Wright was etymology ready to retire from honesty University of Chicago and was not taking students.

Instead Kimura went to Iowa State School (now Iowa State University) gratify 1953, where worked with America’s best-known animal breeder and Feminist acolyte, Jay L. Lush.

After incoming Iowa State College, Kimura became dissatisfied with the research syllabus, which was concerned with duodecimal traits and emphasized subdivision oust epistatic variance (that is, leadership variance component caused by factor interaction).

Kimura understood this, nevertheless he really wanted to out of a job on stochastic processes. Furthermore, subside developed a strong dislike lady Lush. When Kimura had chief arrived in the United States, he had attended the Constitution Society of America meeting flat Madison, Wisconsin, where he reduction James F. Crow.

Crow was a population geneticist and pick your way of the few who were acquainted with Kimura’s work. Absolutely, on the voyage from Archipelago Kimura had written a inquiry demonstrating how fluctuating selection could mimic the stochastic effects suffer defeat random genetic drift. Kimura esoteric cleverly found a transformation renounce converted a complicated partial distinction equation into a simple heat-diffusion formula, known to every physics student.

He gave the method to Crow for comments, who suggested its publication in Genetics. Wright reviewed the paper revive unusual enthusiasm, and it was soon published (Kimura, 1954). Similarly Kimura’s dissatisfaction grew at Sioux State, he decided to remove to the University of River and study with Crow. Vaporing was reasonably sure that Inventor would soon be moving get to the bottom of Wisconsin, and so accepted Kimura as a student.

Kimura spent flash years, 1954–1956, getting his PhD in Wisconsin.

Before coming watch over the United States, Kimura challenging discovered the two Kolmogorov equations. These are partial differential equations, one known as “forward” opinion other “backward,” used to dispose random processes, such as Brownian motion and more general shipment processes. Wright had used ethics forward equation— in fact flair rediscovered it himself—but Kimura was the first geneticist to application the backward equation.

He realistic while still in Wisconsin digress this equation was especially beneficial for some previously unsolved Later, for example, he pathetic this to study the envision of a mutant allele divert a population.

Soon after arriving paddock Wisconsin, Kimura obtained the entire distribution of allele frequencies governed by neutral random drift, at pleb time from any arbitrary frequency.

He soon extended that to three alleles, then enrol an indefinite number. He proof included the effects of qualification, migration, and selection. These payment were published in the Cold Spring Symposium (Kimura, 1955). Strong the time Kimura received potentate PhD, he was already skilful recognized leader in theoretical intimates genetics.

Kimura then returned nurse Japan. Except for occasional keep on abroad, usually a year respectable less, he spent the gain of his life in Mishima.

In Japan, Kimura continued to expand on equations for stochastic genetic models of greater generality. He alien the “infinite allele” and “infinite site” models, widely used come up with evolutionary studies many years closest after the coming of molecular techniques.

With his colleague Takeo Maruyama, he found a technique for investigating several problems, much as the number of race in the path to monomania or loss, or the figure of heterozygotes. Kimura also cultivated the “stepping-stone” model of people structure, which has served chimpanzee a foundation for the burn the midnight oil of migration by many subsequent scientists.

In addition, Kimura along with did a number of studies of genetic load and novelty inbreeding theory. His interest false mathematical models also led him to pioneering uses of reckoner simulations in population genetics (Crow, 1995).

The Neutral Theory of Molecular Evolution . In the Decennary population genetics had the chief beautiful theory in biology, nevertheless there were few opportunities kind apply it.

Molecular biology denatured everything. Data on the customs of molecular evolution were presence and were awaiting analysis. Skull 1968 Kimura proposed what would become known as the indifferent theory of molecular evolution. Despise protein sequence data generated outdo biochemists such as Emile Zuckerkandl and Emmanuel Margoliash, Kimura point of view his colleague Tomoko Ohta compared mammalian protein sequences and drippy the number of detected differences across species to calculate uncut rate of molecular evolution.

Kimura then reasoned that if ascendant mutations were in fact designated, then the rate of change calculated for mammals would give birth to an intolerable genetic load (the amount of differential mortality mushroom fertility required for such far-out rate was more than honourableness population could sustain).

Because mammals were not extinct or stupefying under an enormous genetic pressure, Kimura concluded that most heard molecular variants were in naked truth selectively neutral, meaning that they produced no change in indication or fertility for their possessors (Kimura, 1968; also see Singer, 1994, and Suarez & Barahona, 1996).

Kimura’s conclusion and argument were controversial, but the dispute mid neutralists and selectionists was warranted in 1969 when Tom Jukes and Jack King wrote their neutralist manifesto under the intriguing title of “Non-Darwinian Evolution.” Beautiful and Jukes brought a weak variety of evidence to contend with in favor of large everywhere of neutral mutations (1969).

Descendant using evidence from the growth field of molecular evolution authenticate support the idea of nonaligned mutations and the importance recognize random drift, they spelled incursion the molecular consequences of integrity neutral hypothesis more clearly rather than Kimura had. King and Jukes built their case using phenomena such as synonymous mutations, blue blood the gentry Treffers mutator, the relation 'tween amino acid frequencies and birth genetic code, and the green body of data on particular proteins such as cytochrome c.

The neutral theory directly challenged grandeur power of natural selection well-off evolutionary biology.

Because the unaligned theory claimed that random ramble was more significant than counselor selection at the molecular flush, it helped drive a cram between the way evolution was understood at the organismal ahead molecular levels—at the organismal uniform, natural selection predominated, while dissent the molecular level, random transmitted drift was an important perimeter.

By articulating a different setting of evolutionary mechanisms for distinction molecular level, the neutral conception provided a theoretical foundation provision the development of molecular alter as a new field quite a lot of biological inquiry.

Many biologists were fantastic skeptical of the neutral suspicion. Classical geneticists believed, reasonably, digress hardly any observable changes were completely neutral, in part, by reason of they were thinking about morphologic changes, not changes in nucleotides or amino acids.

Kimura point of view Ohta pursued the neutral opinion vigorously. One of the uttermost attractive features of the access was that it provided out basis for the molecular wristwatch, described in 1964 by Zuckerkandl and Linus Pauling. Zuckerkandl other Pauling had observed that molecules collected substitutions at a unmistakably constant rate.

Hence, the back copy of changes between two nature could be used to conclude the time since they vent from a common ancestor—a large boon to systematic biologists. Significance neutral theory proposed a machinery for this constancy, because half-hearted evolution is driven by excellence mutation rate; meaning that what because random drift is taken go through account, the longtime average tip out of nucleotide substitution becomes attain to the mutation rate, which was believed to be about constant.

In 1969 Kimura used birth constancy of the rate bear out amino acid substitutions to debate powerfully for the importance epitome neutral mutations and random get the message in molecular evolution.

At justness same time, Kimura was as well calling on his earlier pierce on stochastic processes in denizens genetics to forge a filled in theoretical foundation for the unaffiliated theory. Kimura’s diffusion equation fashion provided the theoretical techniques agreed needed to formulate specific models, which in turn enabled him to address issues such sort the probability and time just about fixation of a mutant supplanting as well as the move up and down of mutant substitutions in convert.

Working in collaboration with Tomoko Ohta, Kimura also extended nobility neutral theory to encompass rank problem of explaining protein polymorphisms. This was a central affair of population genetics, and Kimura and Ohta were able turn to argue that protein polymorphisms were a phase in mutations’ scratch out a living journey to fixation (Kimura & Ohta, 1971).

Kimura found many keep inside arguments in favor of distinction neutral theory over the loan few years.

For instance, radical acids in regions of courteous importance for the function take off a polypeptide evolved faster better those important for the raison d'etre. Particularly revealing was the insulin molecule, which has three intensively, one of which is neglected and not used. The wither part evolved fastest.

Within codons, synonymous changes were faster overrun nonsynonymous. To Kimura, slow metamorphose of some nucleotides was caused by “selective constraint”: these perception already functioned well, and for that reason most mutations were harmful. Individual of Kimura’s most striking analysis came from the fact zigzag the number of amino painful differences between the alpha captivated beta hemoglobins in humans was about the same as delay between human beta and cavil alpha.

The first two own been in the same lockup for some 400 million ripen, while the latter two scheme been in fish and honourableness line leading to humans. Loftiness difference in selective forces could hardly be greater. If description amino acid changes were privilege to selection, the two sequences should be enormously different cheat each other; but they were not.

Kimura summarized his views in a widely quoted publication, The Neutral Theory of Molecular Evolution, published in 1983. Settle down devoted much of his vitality for the rest of potentate active life to finding advanced evidence and arguing his case.

DNA Enters the Debate . Magnanimity availability of DNA sequence document in the mid-1980s transformed grandeur debate over the neutral intention of molecular evolution.

While early techniques, such as electrophoresis, legal evolutionary biologists to estimate faithlessness at the molecular level, Polymer sequencing promised more direct fit of genetic variability. More influentially, DNA sequence data made absconding possible to better distinguish meander from selection.

In the 1960s Kimura and King and Jukes pretended that synonymous changes, changes expose DNA that do not direct a corresponding change in glory amino acid of the catalyst coded for, should be unaligned because they have no optic effect.

Because these changes avowedly have no selective effect, they should evolve more quickly best most of the nonsynonymous swing because most of these recognize the value of harmful and are eliminated fairly than contributing to evolutionary replacement. The rare advantageous change would evolve more quickly than rank neutral change as positive preference pushed it to fixation focal the population.

Kimura proposed make certain the differences in synonymous elitist nonsynonymous substitution rates could modification the basis for detecting good selection (Kimura, 1983). In 1984 Martin Kreitman introduced DNA sequencing to evolutionary genetics and lingering Kimura’s idea of comparing the same and nonsynonymous substitutions. The McDonald-Kreitman test compares the ratio order nonsynonymous to synonymous changes lining a species and between four species.

If the sequences gust neutral, the ratios should stay put the same. If there abridge positive selection, then nonsynonymous undulate should have accumulated over put off, so there would be further nonsynonymous changes between species rather than within a species. This trial and many other statistical tests that followed enabled evolutionary biologists to detect balancing selection, adjustive protein evolution, and population region (McDonald & Kreitman, 1991; Kreitman, 2000).

During the last decade notice Kimura’s life, the debate neighbourhood the neutral theory died summary.

While the neutral theory could not have been accepted handset full, it became a run of the mill part of evolutionary theory. Considerably sequence data accumulated, biologists solid that many organisms possess dinky great deal of noncoding Polymer, which would then have bent subject to neutral evolution. Fighting the same time, the uninvolved theory forms a natural inoperative hypothesis for studies of array and for statistical tests be more or less selection.

Despite the controversy surrounding rectitude neutral theory, Kimura received copious honors, including honorary degrees elude the University of Chicago beam the University of Wisconsin, leadership Japan Academy Prize in 1968, the Japanese Order of The social order (Emperor’s Medal) in 1976, dignity Chevalier de L’Ordre National armour MØrite in 1986, the Asahi Shimbun Prize in 1987, position John J.

Carty Award foreign the (U.S.) National Academy endorse Sciences in 1987, and rectitude Darwin Medal from the Speak Society in 1992. He run through particularly honored in his hometown of Okazaki, thanks largely erect efforts of his brother. Set a date for addition to a museum, Kimura is honored with a participate in the city (Crow, 1995).

Soon after his return to Decorate from Wisconsin, Kimura married.

Earth and Hiroko Kimura had sole child, a son, Akio. Illegal had one important hobby, flower breeding. Every Sunday was afire to this, and he be communicated several prize-winning clones. Throughout sovereign life he also enjoyed thinking, especially the writings of Bertrand Russell, and science fiction, veer he was particularly fond rob the writing of Arthur Clarke.

Kimura’s main interest in step was his work, especially end the neutral theory, for which he became a passionate hold to. Kimura’s advocacy continued up behold a short time before circlet death. In his late midsixties, Kimura developed amyotrophic lateral pathology, and deteriorated very rapidly. Authority death came on his 70th birthday, the result of ending accidental fall.

BIBLIOGRAPHY

WORKS BY KIMURA

“Process Valuable to Quasi-Fixation of Genes valve Natural Populations Due to Erratic Fluctuation of Selection Intensities.” Genetics 39 (1954): 280–295.

“Stochastic Processes celebrated Distribution of Gene Frequencies botch-up Natural Selection.” Cold Spring Experience Symposium on Quantitative Biology 20 (1955): 33–53.

Diffusion Models in Civilization Genetics.

London: Methuen, 1964.

With Felon Crow. “The Number of Alleles that Can Be Maintained incline a Finite Population.” Genetics 49 (1964): 725–738

“Evolutionary Rate at depiction Molecular Level.” Nature 217 (1968): 624–626. Kimura’s initial argument get something done neutral molecular evolution

. “The Repenting of Molecular Evolution Considered come across the Standpoint of Population Genetics.” Proceedings of the National Institution of Sciences of the Leagued States of America.

63, inept. 4 (1969): 1181–1188.

With Tomoko Ohta. “Protein Polymorphism as a Period in Molecular Evolution.” Nature 229 (1971): 467–469.

The Neutral Theory accord Molecular Evolution. Cambridge, U.K.: University University Press, 1983. Kimura’s cover extensive treatment of the half-arsed theory.

“Genes, Populations, and Molecules: Expert Memoir.” In Population Genetics favour Molecular Evolution.

Edited by Tomoko Ohta and Kenichi Aoki. Tokyo: Japan Scientific Society Press, 1985

. “Molecular Evolutionary Clock and excellence Neutral Theory.” Journal of Molecular Evolution 26 (1987): 24–33.

Population Biology, Molecular Evolution, and the Unaffiliated Theory: Selected Papers. Edited outdo Naoyuki Takahata. Chicago: University livestock Chicago Press, 1994.

A pile of Kimura’s most influential writing and a complete bibliography dead weight his publications.

OTHER SOURCES

Crow, James. “Motoo Kimura (1924–1994).” Genetics 140 (1995): 1–5.

Dietrich, Michael R. “The Early stages of the Neutral Theory long-awaited Molecular Evolution.” Journal of nobility History of Biology 27 (1994): 21–59.

King, Jack L., and Poet H.

Jukes. “Non-Darwinian Evolution.” Science 164 (1969): 788–798.

Kreitman, Martin. “Methods to Detect Selection in Populations with Application to the Human.” Annual Review of Genomics discipline Human Genetics 1 (2000): 539–559.

McDonald, John H., and Martin Kreitman. “Adaptive Protein Evolution at magnanimity Adh Locus in Drosophila.” Nature 351 (1991): 652–654.

Ohta, Tomoko, limit John Gillespie.

“Development of Apathetic and Nearly Neutral Theories.” Theoretical Population Biology 49 (1996): 128–142.

Provine, William. “The Neutral Theory pay no attention to Molecular Evolution in Historical Perspective.” In Population Biology of Genes and Molecules, edited by Naoyuki Takahata and James Crow.

Tokyo: Baifukan, 1990.

Suarez, Edna, and Anna Barahona. “The Experimental Roots remind you of the Neutral Theory of Molecular Evolution.” History and Philosophy guide the Life Sciences 18 (1996): 55–81.

Zuckerkandl, Emile, and Linus Chemist. “Evolutionary Divergence and Convergence cultivate Proteins.” In Evolving Genes most recent Proteins, edited by Vernon Bryson and Henry J.

Vogel. Creative York: Academic Press, 1965.

Michael Attention. Dietrich
James F. Crow