Andrew Huxley

Sir Andrew Fielding Huxley OM PRS (22 November 1917 – 30 May 2012) was an English physiologist and biophysicist.[1][2] He was born into the prominent Huxley family. After graduating from Westminster School in Central London, from where he won a scholarship to Trinity College, Cambridge, he joined Alan Lloyd Hodgkin to study nerve impulses. Their eventual discovery of the basis for propagation of nerve impulses (called an action potential) earned them the Nobel Prize in Physiology or Medicine in 1963. They made their discovery from the giant axon of the Atlantic squid. Soon after the outbreak of the Second World War, Huxley was recruited by the British Anti-Aircraft Command and later transferred to the Admiralty. After the war he resumed research at The University of Cambridge, where he developed interference microscopy that would be suitable for studying muscle fibres.

In 1952, he was joined by a German physiologist Rolf Niedergerke. Together they discovered in 1954 the mechanism of muscle contraction, popularly called the "sliding filament theory", which is the foundation of our modern understanding of muscle mechanics. In 1960 he became head of the Department of Physiology at University College London. He was elected a Fellow of the Royal Society in 1955, and President in 1980. The Royal Society awarded him the Copley Medal in 1973 for his collective contributions to the understanding of nerve impulses and muscle contraction. He was conferred a Knight Bachelor by Queen Elizabeth II in 1974, and was appointed to the Order of Merit in 1983. He was a fellow of Trinity College, Cambridge, until his death.

Sir Andrew Huxley

Andrew Fielding Huxley nobel
Huxley in 1963
Born
Andrew Fielding Huxley

22 November 1917
Died30 May 2012 (aged 94)
ResidenceGrantchester, Cambridge, England
NationalityEnglish
CitizenshipBritish
Alma materTrinity College, Cambridge
Known forNerve action potentials, muscle contraction
Spouse(s)J. Richenda G. Pease
(1947–2003)
Children1 son and 5 daughters
Awards
Scientific career
FieldsPhysiology and biophysics
Institutions

Early life and education

Huxley was born in Hampstead, London, England, on 22 November 1917. He was the youngest son of the writer and editor Leonard Huxley by Leonard Huxley's second wife Rosalind Bruce, and hence half-brother of the writer Aldous Huxley and fellow biologist Julian Huxley, and grandson of the biologist T. H. Huxley.

When he was about 12, Andrew and his brother David were given a lathe by their parents. Andrew soon became proficient at designing, making and assembling mechanical objects of all kinds, from wooden candle sticks to a working internal combustion engine. He used these practical skills throughout his career, building much of the specialized equipment he needed for his research. It was also in his early teens that he formed his lifelong interest in microscopy.[3]

He was educated at University College School and Westminster School in Central London, where he was a King's Scholar.[4] He graduated and won a scholarship to Trinity College, Cambridge, to read natural sciences. He had intended to become an engineer but switched to physiology after taking the subject to fulfill an elective.[5]

Career

Having entered Cambridge in 1935, Huxley graduated with a bachelor's degree in 1938. In 1939, Alan Lloyd Hodgkin returned from the US to take up a fellowship at Trinity College, and Huxley became one of his postgraduate students. Hodgkin was interested in the transmission of electrical signals along nerve fibres. Beginning in 1935 in Cambridge, he had made preliminary measurements on frog sciatic nerves suggesting that the accepted view of the nerve as a simple, elongated battery was flawed. Hodgkin invited Huxley to join him researching the problem. The work was experimentally challenging. One major problem was that the small size of most neurons made it extremely difficult to study them using the techniques of the time. They overcame this by working at the Marine Biological Association laboratory in Plymouth using the giant axon of the longfin inshore squid (Doryteuthis (formerly Loligo) pealeii), which have the largest neurons known.[6] The experiments were still extremely challenging as the nerve impulses only last a fraction of a millisecond, during which time they needed to measure the changing electrical potential at different points along the nerve. Using equipment largely of their own construction and design, including one of the earliest applications of a technique of electrophysiology known as the voltage clamp, they were able to record ionic currents. In 1939, they jointly published a short paper in Nature reporting on the work done in Plymouth and announcing their achievement of recording action potentials from inside a nerve fibre.[7]

Then World War II broke out, and their research was abandoned. Huxley was recruited by the British Anti-Aircraft Command, where he worked on radar control of anti-aircraft guns. Later he was transferred to the Admiralty to do work on naval gunnery, and worked in a team led by Patrick Blackett. Hodgkin, meanwhile, was working on the development of radar at the Air Ministry. When he had a problem concerning a new type of gun sight, he contacted Huxley for advice. Huxley did a few sketches, borrowed a lathe and produced the necessary parts.

Huxley was elected to a research fellowship at Trinity College, Cambridge, in 1941. In 1946, with the war ended, he was able to take this up and to resume his collaboration with Hodgkin on understanding how nerves transmit signals. Continuing their work in Plymouth, they were, within six years, able to solve the problem using equipment they built themselves. The solution was that nerve impulses, or action potentials, do not travel down the core of the fiber, but rather along the outer membrane of the fiber as cascading waves of sodium ions diffusing inward on a rising pulse and potassium ions diffusing out on a falling edge of a pulse. In 1952, they published their theory of how action potentials are transmitted in a joint paper, in which they also describe one of the earliest computational models[8] in biochemistry. This model forms the basis of most of the models used in neurobiology during the following four decades.[9]

In 1952, having completed work on action potentials, Huxley was teaching physiology at Cambridge and became interested in another difficult, unsolved problem: how does muscle contract? To make progress on understanding the function of muscle, new ways of observing how the network of filaments behave during contraction were needed. Prior to the war, he had been working on a preliminary design for interference microscopy, which at the time he believed to be original, though it turned out to have been tried 50 years before and abandoned. He, however, was able to make interference microscopy work and to apply it to the problem of muscle contraction with great effect. He was able to view muscle contraction with greater precision than conventional microscopes, and to distinguish types of fiber more easily. By 1953, with the assistance of Rolf Niedergerke, he began to find the features of muscle movement. Around that time, Hugh Huxley and Jean Hanson came to a similar observation. Authored in pairs, their papers were simultaneously published in the 22 May 1954 issue of Nature.[10][11] Thus the four people introduced what is called the sliding filament theory of muscle contractions.[12] Huxley synthesized his findings, and the work of colleagues, into a detailed description of muscle structure and how muscle contraction occurs and generates force that he published in 1957.[13] In 1966 his team provided the proof of the theory, and has remained the basis of modern understanding of muscle physiology.[14]

In 1953, Huxley worked at Woods Hole, Massachusetts, as a Lalor Scholar. He gave the Herter Lectures at Johns Hopkins Medical School in 1959 and the Jesup Lectures at Columbia University in 1964. In 1961 he lectured on neurophysiology at Kiev University as part of an exchange scheme between British and Russian professors.

He was an editor of the Journal of Physiology from 1950 to 1957 and also of the Journal of Molecular Biology. In 1955, he was elected a Fellow of the Royal Society and served on the Council of the Royal Society from 1960 to 1962.[15]

Huxley held college and university posts in Cambridge until 1960, when he became head of the Department of Physiology at University College London. In addition to his administrative and teaching duties, he continued to work actively on muscle contraction, and also made theoretical contributions to other work in the department, such as that on animal reflectors.[16] In 1963, he was jointly awarded the Nobel Prize in Physiology or Medicine for his part in discoveries concerning the ionic mechanisms of the nerve cell.[17] In 1969 he was appointed to a Royal Society Research Professorship, which he held in the Department of Physiology at University College London.

In 1980, Huxley was elected as President of the Royal Society, a post he held until 1985. In his Presidential Address in 1981, he chose to defend the Darwinian explanation of evolution, as his ancestor, T. H. Huxley had in 1860. Whereas T. H. Huxley was defying the bishops of his day, Sir Andrew was countering new theories of periods of accelerated change. In 1983, he defended the Society's decision to elect Margaret Thatcher as a fellow on the ground of her support for science even after 44 fellows had signed a letter of protest.

In 1984, he was elected Master of Trinity, succeeding his longtime collaborator, Sir Alan Hodgkin. His appointment broke the tradition that the office of Master of Trinity alternates between a scientist and an arts man. He was Master until 1990 and was fond of reminding interviewers that Trinity College had more Nobel Prize winners than did the whole of France. He maintained up to his death his position as a fellow at Trinity College, Cambridge, teaching in physiology, natural sciences and medicine.[18] He was also a fellow of Imperial College London in 1980.[19]

From his experimental work with Hodgkin, Huxley developed a set of differential equations that provided a mathematical explanation for nerve impulses—the "action potential". This work provided the foundation for all of the current work on voltage-sensitive membrane channels, which are responsible for the functioning of animal nervous systems. Quite separately, he developed the mathematical equations for the operation of myosin "cross-bridges" that generate the sliding forces between actin and myosin filaments, which cause the contraction of skeletal muscles. These equations presented an entirely new paradigm for understanding muscle contraction, which has been extended to provide understanding of almost all of the movements produced by cells above the level of bacteria. Together with the Swiss physiologist Robert Stämpfli, he evidenced the existence of saltatory conduction in myelinated nerve fibres.

Awards

Huxley, Alan Hodgkin and John Eccles jointly won the 1963 Nobel Prize in Physiology or Medicine "for their discoveries concerning the ionic mechanisms involved in excitation and inhibition in the peripheral and central portions of the nerve cell membrane". Huxley and Hodgkin won the prize for experimental and mathematical work on the process of nerve action potentials, the electrical impulses that enable the activity of an organism to be coordinated by a central nervous system.[20] Eccles had made important discoveries on synaptic transmission.

Huxley was elected a Fellow of the Royal Society (FRS) in 1955, and was awarded its Copley Medal in 1973 "in recognition of his outstanding studies on the mechanisms of the nerve impulse and of activation of muscular contraction."[21] He was knighted by Queen Elizabeth II on 12 November 1974. He was appointed to the Order of Merit on 11 November 1983. In 1976–77, he was President of the British Science Association and from 1980 to 1985 he served as President of the Royal Society.

Huxley's portrait by David Poole hangs in Trinity College's collection.[22]

Personal life

In 1947, Huxley married Jocelyn "Richenda" Gammell (née Pease), the daughter of the geneticist Michael Pease (a son of Edward R. Pease) and his wife Helen Bowen Wedgwood, eldest daughter of the first Lord Wedgwood (see also Darwin-Wedgwood family). They had one son and five daughters – Janet Rachel Huxley (born 20 April 1948), Stewart Leonard Huxley (born 19 December 1949), Camilla Rosalind Huxley (born 12 March 1952), Eleanor Bruce Huxley (born 21 February 1959), Henrietta Catherine Huxley (born 25 December 1960), and Clare Marjory Pease Huxley (born 4 November 1962).

Death

Huxley died on 30 May 2012. He was survived by his six children, grandchildren, and great-grandchildren. His wife Richenda, Lady Huxley died in 2003, aged 78. A funeral service was held in Trinity College Chapel on 13 June 2012, followed by a private cremation.[23]

Publications

  • Huxley, A. F., 1980. Reflections on muscle. The Sherrington Lectures XIV. Liverpool.

See also

References

  1. ^ Huxley, Andrew F. (1996). "Andrew F. Huxley". In Squire, Larry R. (ed.). The History of Neuroscience in Autobiography. Washington DC: Society for Neuroscience. pp. 283–318. ISBN 978-0-12-660246-3.
  2. ^ Goldman, Yale E.; Franzini-Armstrong, Clara; Armstrong, Clay M. (2012). "Andrew Fielding Huxley (1917–2012)". Nature. 486 (7404): 474. Bibcode:2012Natur.486..474G. doi:10.1038/486474a.
  3. ^ Tucker, Anthony (31 May 2012). "Sir Andrew Huxley". London: The Guardian 31 May 2012. Retrieved 24 February 2013.
  4. ^ "Obituary of Sir Andrew Huxley". London: The Telegraph. Retrieved 24 February 2013.
  5. ^ "Andrew F. Huxley - Biographical". Nobelprize.org. Nobel Media AB.
  6. ^ Hellier, Jennifer L. (2014). The Brain, the Nervous System, and Their Diseases. ABC-Clio. p. 532. ISBN 9781610693387.
  7. ^ Hodgkin, A. L.; Huxley, A. F. (1939). "Action potentials recorded from Inside a nerve fibre". Nature. 144 (3651): 710–711. Bibcode:1939Natur.144..710H. doi:10.1038/144710a0.
  8. ^ one of the earliest computational models
  9. ^ Reilly, J.P.; Diamant, A.M. (2011). Electrostimulation. Artech House. pp. 20–21. ISBN 978-1-60807-108-1.
  10. ^ Huxley, A.F.; Niedergerke, R. (1954). "Structural changes in muscle during contraction; interference microscopy of living muscle fibres". Nature. 173 (4412): 971–3. Bibcode:1954Natur.173..971H. doi:10.1038/173971a0. PMID 13165697.
  11. ^ Huxley, H.; Hanson, J. (1954). "Changes in the cross-striations of muscle during contraction and stretch and their structural interpretation". Nature. 173 (4412): 973–76. Bibcode:1954Natur.173..973H. doi:10.1038/173973a0. PMID 13165698.
  12. ^ Huxley, A.F (1954). "A high-power interference microscope". J. Physiol. 125: 11–13. doi:10.1113/jphysiol.1954.sp005186.
  13. ^ Huxley, A.F. (1957). "Muscle structure and theories of contraction". Prog. Biophys. Biophys. Chem. 7: 255–318. doi:10.1016/S0096-4174(18)30128-8.
  14. ^ Gordon, AM; Huxley, AF; Julian, FJ (1966). "The variation in isometric tension with sarcomere length in vertebrate muscle fibres". The Journal of Physiology. 184 (1): 170–92. doi:10.1113/jphysiol.1966.sp007909. PMC 1357553. PMID 5921536.
  15. ^ Malcolm Simmons, Robert (2018). "Sir Andrew Fielding Huxley OM. 22 November 1917—30 May 2012". Biographical Memoirs of Fellows of the Royal Society. doi:10.1098/rsbm.2018.0012
  16. ^ Huxley, A.F. (1954). "A theoretical treatment of reflexion of light by multilayer structures". J. Exp. Biol. 48 (2): 227–245.
  17. ^ "Nobel Prizes in Medicine 1963".
  18. ^ The Master of Trinity at Trinity College, Cambridge
  19. ^ "Nobel Laureates associated with Imperial College London". Imperial College London.
  20. ^ Anthony Tucker (31 May 2012). "Sir Andrew Huxley | Science". London: The Guardian. Retrieved 31 May 2012.
  21. ^ "Copley Medal". The Royal Society.
  22. ^ "Trinity College, University of Cambridge". BBC Your Paintings. Archived from the original on 11 May 2014. Retrieved 12 February 2018.
  23. ^ "Sir Andrew Huxley (1917–2012)". Trinity College, Cambridge. Retrieved 25 February 2014.

External links

Academic offices
Preceded by
Richard John Harrison
Fullerian Professor of Physiology
1967–1973
Succeeded by
Max Ferdinand Perutz
Preceded by
Alexander Robertus Todd
President of the Royal Society
1980–1985
Succeeded by
George Porter
Preceded by
Sir Alan Hodgkin
Master of Trinity College, Cambridge
1984–1990
Succeeded by
Sir Michael Atiyah
1917 in science

The year 1917 in science and technology involved some significant events, listed below.

Alan Lloyd Hodgkin

Sir Alan Lloyd Hodgkin (5 February 1914 – 20 December 1998) was an English physiologist and biophysicist, who shared the 1963 Nobel Prize in Physiology or Medicine with Andrew Huxley and John Eccles.

Andrew D. Huxley

Andrew D. Huxley (born 1966) is a chair of the physics department of the University of Edinburgh.

Classical interference microscopy

Classical interference microscopy, also called quantitative interference microscopy, uses two separate light beams with much greater lateral separation than that used in phase contrast microscopy or in differential interference microscopy (DIC).

In variants of the interference microscope where object and reference beam pass through the same objective, two images are produced of every object (one being the "ghost image"). The two images are separated either laterally within the visual field or at different focal planes, as determined by the optical principles employed. These two images can be a nuisance when they overlap, since they can severely affect the accuracy of mass thickness measurements. Rotation of the preparation may thus be necessary, as in the case of DIC.

One of the first usable interference microscopes was designed by Dyson and manufactured by Cooke, Troughton & Simms (later Vickers Instruments), York England. This ingenious optical system achieved interference imaging without requiring polarizing elements in the beam path.

A later popular design involving polarizing elements was designed by Smith and marketed first by C. Baker, London, and subsequently by the American Optical Company in the US.

The double-image problem commonly encountered with all the above-mentioned designs was completely avoided in the Mach–Zehnder interferometer design implemented by Horn, a most expensive instrument, not employing polarized light, but requiring precisely-matched duplicated objectives and condensers. With this design (marketed by E. Leitz) 60 mm beam separation was achieved in microscopy but here the new difficulty has arisen of balancing optical thicknesses of two separate microscope slide preparations (sample and dummy) and maintaining this critical balance during longer observations (e.g. time-lapse studies of living cells maintained at 37 °C), otherwise a gradual change in background interference colour occurs over time.

The main advantage offered by interference microscopy measurements is the possibility of measuring the projected dry mass of living cells, which was first effectively exploited by Andrew Huxley in studies of striated muscle cell structure and function, leading to the sliding filament model of muscle contraction.

Interference microscopy became relatively popular in the 1940–1970 decades but fell into disuse because of the complexity of the instrument and difficulties in both its use and in the interpretation of image data. In recent years, however, the classical interference microscope (in particular the Mach–Zehnder instrument) has been "rediscovered" by biologists because its main original disadvantage (difficult interpretation of translated interference bands or complex coloured images) can now be easily surmounted by means of digital camera image recording, followed by the application of computer algorithms which rapidly deliver the processed data as false-colour images of projected dry mass. Examples of computer-assisted developments of the technique are found in the application of "DRIMAPS" from the laboratory of Graham Dunn and other recent developments of the methodology are described by Mahlmann et al. Interference microscopy for industrial inspection, semiconductor inspection and surface structure analysis is highly developed and in widespread use.

David Poole

David Poole may refer to:

David Poole (judge) (1938–2006), English High Court judge

David Poole (footballer) (born 1984), English footballer

David Poole (dancer) (1925–1991), South African ballet dancer

David Poole (researcher), artificial intelligence and machine learning researcher at University of British Columbia

David Poole (artist), portrait painter, see Andrew Huxley

Department of Physiology, Development and Neuroscience, University of Cambridge

The Department of Physiology, Development and Neuroscience, (PDN) is a part of the School of Biological Sciences at the University of Cambridge. Research in PDN focuses on three main areas: Cellular and Systems Physiology, Developmental and Reproductive Biology, and Neuroscience and is currently headed by Sarah Bray and William Colledge. The department was formed on 1 January 2006, within the School of Biological Sciences at the University of Cambridge from the merger of the Departments of Anatomy and Physiology. The department hosts the Centre for Trophoblast Research and has links with the Cambridge Centre for Brain Repair, the Cambridge Stem Cell Institute, and the Gurdon Institute.

Huxley (surname)

Huxley is an English surname, originally given to people from Huxley, Cheshire. Notable people with the surname include:

The British Huxley family:

Thomas Henry Huxley (1825–1895), British biologist, supporter of Charles Darwin and inventor of the term 'agnosticism'

Leonard Huxley (writer) (1860–1933), British writer and editor, son of Thomas Henry

Aldous Huxley (1894–1963), British writer, son of Leonard and author of Brave New World

Sir Julian Huxley (1887–1975), British biologist and author, son of Leonard

Sir Andrew Huxley (1917–2012), British physiologist and biophysicist, son of Leonard

Elspeth Huxley (1907–1997), British writer, granddaughter-in-law of Thomas

Sir Leonard Huxley (physicist) (1902–1988), Australian physicist, second cousin once-removed of Thomas Huxley

Anthony Julian Huxley (1920–1992), British botanist with the standard author abbreviation "Huxley"

Huxley family

The Huxley family is a British family of which several members have excelled in science, medicine, arts, and literature. The family also includes members who occupied senior positions in the public service of the United Kingdom.

The patriarch of the family was the zoologist and comparative anatomist Thomas Henry Huxley (1825–1895). His grandsons include Aldous Huxley (author of Brave New World and Doors of Perception) and his brother Julian Huxley (an evolutionist, and the first director of UNESCO), and Nobel laureate physiologist Andrew Huxley.

John Eccles (neurophysiologist)

Sir John Carew Eccles (27 January 1903 – 2 May 1997) was an Australian neurophysiologist and philosopher who won the 1963 Nobel Prize in Physiology or Medicine for his work on the synapse. He shared the prize with Andrew Huxley and Alan Lloyd Hodgkin.

List of Fellows of the Royal Society elected in 1955

This page lists Fellows of the Royal Society elected in 1955.

List of Nobel laureates affiliated with University College London

University College London (UCL) is one of the two founding colleges of the University of London. There have been 33 Nobel Prize laureates amongst UCL’s alumni and current and former staff. UCL has the most Nobel affiliations among colleges and schools of the University of London, which has produced as many as 72 Nobelists till 2010.

Marine Biological Association of the United Kingdom

The Marine Biological Association of the United Kingdom (MBA) is a learned society with a scientific laboratory that undertakes research in marine biology. The organisation was founded in 1884 and has been based in Plymouth since the Citadel Hill Laboratory was opened on 30 June 1888. It has a world-leading reputation for marine biological research, with some twelve Nobel laureates having been or being associated with it over the course of their career. Among them, A. V. Hill received the Nobel Prize in Physiology or Medicine in 1922 "for his discovery relating to the production of heat in the muscle". The discovery of the mechanism of nerve impulses (action potentials) in animals was made at the Laboratory in Plymouth by Sir Alan Lloyd Hodgkin and Sir Andrew Huxley, work for which they were awarded the Nobel Prize for Physiology or Medicine in 1963. The MBA publishes the Journal of the Marine Biological Association of the United Kingdom. The MBA is also home to the National Marine Biological Library, whose collections cover the marine biological sciences, and curates the Historical Collections.

Throughout its history, the MBA has had a Royal Patron. The current patron of the MBA is H.R.H. The Prince Philip, Duke of Edinburgh. In 2013, the MBA was granted a Royal Charter in recognition of the MBA's scientific preeminence in its field.

Michael Pease

Michael Stewart Pease OBE (2 October 1890 – 27 July 1966) was a British classical geneticist at Cambridge University.

Michael Pease was the son of Edward Reynolds Pease, writer and a founding member of the Fabian Society, of the Pease family of Quakers. He was educated at Trinity College, Cambridge, where he was elected chairman of the Cambridge University Fabian Society. On 24 February 1920 he married Helen Bowen Wedgwood, daughter of the Labour politician Josiah Wedgwood IV (later 1st Baron Wedgwood), of the Wedgwood pottery family at Chelsea Register Office. Their children include the physicist Bas Pease and Jocelyn Richenda Gammell Pease (1925–2003), who married the Nobel Prize–winning biologist Andrew Huxley.

He worked at the Genetical Institute of Cambridge as assistant to Reginald Crundall Punnett, who created the first auto-sexing chicken breeds, the Cambar and Legbar, in which the sex of day-old chicks was clearly distinguishable from the plumage. When, in 1930, a separate poultry research facility was established, Pease headed it. He also served as a Labour councillor on the Cambridge County Council for Girton. He was appointed to be an Ordinary Officers of the Civil Division of the Order of the British Empire in 1966 for political and public services in Cambridgeshire.He was held in the civilian internment camp at Ruhleben, near Berlin, during the First World War. His father, a Major at the time, asked whether he could be exchanged for a German prisoner wishing to return to Berlin, but without success. While interned Pease tried to get gardens put into the camp and on 27 April 1916 gave a lecture on dancing in Elizabethan times.

Neuroethology

Neuroethology is the evolutionary and comparative approach to the study of animal behavior and its underlying mechanistic control by the nervous system. This interdisciplinary branch of behavioral neuroscience endeavors to understand how the central nervous system translates biologically relevant stimuli into natural behavior. For example, many bats are capable of echolocation which is used for prey capture and navigation. The auditory system of bats is often cited as an example for how acoustic properties of sounds can be converted into a sensory map of behaviorally relevant features of sounds. Neuroethologists hope to uncover general principles of the nervous system from the study of animals with exaggerated or specialized behaviors.

As its name implies, neuroethology is a multidisciplinary field composed of neurobiology (the study of the nervous system) and ethology (the study of animal behavior in natural conditions). A central theme of the field of neuroethology, delineating it from other branches of neuroscience, is this focus on natural behavior, which may be thought of as those behaviors generated through means of natural selection (i.e. finding mates, navigation, locomotion, predator avoidance) rather than behaviors in disease states, or behavioral tasks that are particular to the laboratory.

Rolf Niedergerke

Rolf Nidergerke (30 April 1921 – 27 December 2011) was a German physiologist and physician, and one of the discoverers of the sliding filament theory of muscle contraction. He and Andrew Huxley, complimenting the independent works of Hugh Huxley and Jean Hanson, revealed that muscle contraction is due to shortening of the muscle fibres. He studied medicine throughout the Second World War, and obtained his MD degree as the war ended in 1945. After a brief practise in his hometown, he chose a research career. He became associated with Huxley, whom he joined at Cambridge University. Together they published a landmark paper in Nature in 1954, which became the foundation of muscle mechanics.

Sliding filament theory

The sliding filament theory explains the mechanism of muscle contraction based on muscle proteins that slide past each other to generate movement. It was independently introduced in 1954 by two research teams, one consisting of Andrew F. Huxley and Rolf Niedergerke from the University of Cambridge, and the other consisting of Hugh Huxley and Jean Hanson from the Massachusetts Institute of Technology. It was originally conceived by Hugh Huxley in 1953. Andrew Huxley and Niedergerke introduced it as a "very attractive" hypothesis.According to the sliding filament theory, the myosin (thick) filaments of muscle fibers slide past the actin (thin) filaments during muscle contraction, while the two groups of filaments remain at relatively constant length. Before the 1950s there were several competing theories on muscle contraction, including electrical attraction, protein folding, and protein modification. The novel theory directly introduced a new concept called cross-bridge theory (classically swinging cross-bridge, now mostly referred to as cross-bridge cycle) which explains the molecular mechanism of sliding filament. Cross-bridge theory states that actin and myosin form a protein complex (classically called actomyosin) by attachment of myosin head on the actin filament, thereby forming a sort of cross-bridge between the two filaments. These two complementary hypotheses turned out to considered the correct description, and became a universally accepted explanation of the mechanism of muscle movement.

Squid giant axon

The squid giant axon is the very large (up to 1.5 mm in diameter; typically around 0.5 mm) axon that controls part of the water jet propulsion system in squid. It was first described by L. W. Williams in 1909,[page needed] but this discovery was forgotten until English zoologist and neurophysiologist J. Z. Young demonstrated the axon's function in the 1930s while working in the Stazione Zoologica in Naples, the Marine Biological Association in Plymouth and the Marine Biological Laboratory in Woods Hole. Squids use this system primarily for making brief but very fast movements through the water.

Between the tentacles of a squid is a siphon through which water can be rapidly expelled by the fast contractions of the body wall muscles of the animal. This contraction is initiated by action potentials in the giant axon. Action potentials travel faster in a larger axon than a smaller one,[page needed] and squid have evolved the giant axon to improve the speed of their escape response. The increased diameter of the squid axon decreases the internal resistance of the axon, as resistance is inversely proportional to the cross sectional area of the object. This increases the space constant (), leading to faster local depolarization and a faster action potential ().[page needed]

In their Nobel Prize-winning work uncovering ionic mechanism of action potentials, Alan Hodgkin and Andrew Huxley performed experiments on the squid giant axon, using the longfin inshore squid as the model organism. The prize was shared with John Eccles. The large diameter of the axon provided a great experimental advantage for Hodgkin and Huxley as it allowed them to insert voltage clamp electrodes inside the lumen of the axon.

While the squid axon is very large in diameter it is unmyelinated which decreases the conduction velocity substantially. The conduction velocity of a typical 0.5 mm squid axon is about 25 m/s. During a typical action potential in the cuttlefish Sepia giant axon, an influx of 3.7 pmol/cm2 (picomoles per centimeter2) of sodium is offset by a subsequent efflux of 4.3 pmol/cm2 of potassium.

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