Colin Pittendrigh
Encyclopedia
Colin Pittendrigh was a US-American biologist
of English parentage. He is a co-founder of modern chronobiology
along with Jürgen Aschoff
and Erwin Bünning
.
(today Tyne and Wear
) and received his first degree in botany
at King's College, Newcastle upon Tyne, University of Durham, now University of Newcastle upon Tyne
. He married and had two children, Robin and Colin Jr. (Sandy). During World War II
the British Government sent him to Trinidad
, where he studied the epidemiology
of malaria
transmitted by mosquitoes breeding in the bromeliad ponds ("tanks" formed by overlapping leaves), making acute observations on bromeliad distribution within forest canopies and between contrasting forest formations. His work with the biting rhythms of these mosquitoes piqued his interest in biological rhythms.
After the war, Pittendrigh attended Columbia University
to study for his Ph.D.
under the evolutionary geneticist Theodosius Dobzhansky
. In 1947 he joined the faculty at Princeton
, where he began his work on on circadian rhythm
. He became a U.S. citizen in 1950; in 1969 he joined the faculty of Stanford where he helped found the program in Human Biology and later became the director of the Hopkins Marine Station
. He died of cancer on March 19, 1996 in his home in Bozeman, Montana
. His favorite hobby was fly-fishing.
he laid the groundwork for today's understanding of chronobiology
; investigating such topics as human wake/sleep cycles
, hibernation
, the navigation
of animals, and jetlag. Pittendrigh became close friends with Aschoff when the latter visited the United States
in 1958. Aschoff's visit inspired the two to organize the 1960 Cold Spring Harbor
symposium, which marked the recognition of the new field of chronobiology.
Pittendrigh also established the concept of teleonomy
, a quality determined through objective principles as described in the book Behavior and Evolution (1958, edited by Anne Roe and George Gaylord Simpson). A teleonomic act or characteristic is one which owes its usefulness to the workings of a program. Pittendrigh applied this concept to knowledge of cellular control mechanisms. He purposefully positioned his concept of teleonomy against the concept of teleology
, which he believed to be an unscientific and idealistic approach to the interpretation of biological control mechanisms.
must have in order to be considered a biological clock. His work studying the eclosion rhythms of Drosophila pseudoobscura
demonstrated that 1) eclosion rhythms persist without environmental cues (i.e. in constant conditions), 2) unlike most chemical reactions, the period of eclosion remains relatively constant when exposed to changes in ambient temperature ("temperature compensation"), and 3) eclosion rhythms can be entrained
by light cycles that are close to the flies' natural period.
Beginning in 1958, Pittendrigh developed the concept of the phase response curve
or PRC. The PRC allowed chronobiologists to predict how a biological system would be affected by a change in its light schedule. Although biologists, including Pittendrigh himself, acknowledge that the PRC is a simplified model, it is still used today to teach the concept of non-parametric entrainment (see below).
Pittendrigh and Aschoff proposed two different models for the entrainment of the biological clock to external light cycles. Aschoff, noting that the internal clock's period depends on the length of the day, began with a parametric model in which the period of the internal clock shortens or lengthens in order to align with the external period. Pittendrigh's research with pulses of light and PRCs led him to propose a non-parametric model of entrainment in which pulses of light instantaneously shift the phase
of the biological clock, while the intrinsic period remains constant.
Evidence for Pittendrigh's model was presented in his 1976 paper, "A Functional Analysis of Circadian Pacemakers in Nocturnal Rodents," written in collaboration with Serge Daan
. They showed that significant phase advances and delays could be induced in nocturnal rodents simply through the application of a single 15-minute light pulse at specific times of the rodents’ subjective night. Pittendrigh and Daan also demonstrated the history dependence of free running period, or the effects of prior light conditions on free running period in constant darkness (DD). Part II of the paper also develops certain observations regarding PRCs; Pittendrigh and Daan put forth that range of entrainment can be predicted by examination of the largest delay and the largest advance on a PRC. PRCs were found to have similar advance and delay zones, across species. However, species with a longer wake-sleep period tended to have larger advance zones as compared to delay zones whereas species with relatively short wake-sleep periods were found to have larger delay zones as compared to advance zones. Moreover, Pittendrigh and Daan argued that pacemaker accuracy was greater than rhythm accuracy. Part III demonstrated that various chemical stimuli can affect the period of mice, in this case ingestion of D2O causes the period to lengthen by up to 1.8 hours. D2O was later shown to lengthen the period of cockroaches as well. The use of chemicals to affect circadian periods and oscillations has led to the production of many new pharmaceutical drugs that aim to treat a variety of sleeping disorders. In part IV, Pittendrigh and Daan expanded their model to a two-pulse system (or “skeleton photoperiod”) with one flash at dawn and one at dusk to account for differences in day lengths. This model accurately predicts entrainment for photoperiods up to 12 hours, after which point a “Psi Jump” occurs (the organism switches which pulse is dawn and dusk). From these experiments, the concept of bistability was derived, showing that organisms are able to stably entrain to two different skeleton photoperiods each with a different phase relationship. In part V of the paper, "Pacemaker Structure: A Clock for All Seasons", Pittendrigh and Daan reported the phenomenon of alpha-splitting, in which animals develop two bouts of activity per 24 hour cycle, instead of one, in constant light (LL). Following these observations, they proposed a dual oscillator model, in which the pacemaker is composed of two mutually coupled oscillators, E and M, which regulate evening and morning activity peaks, respectively.
Biologist
A biologist is a scientist devoted to and producing results in biology through the study of life. Typically biologists study organisms and their relationship to their environment. Biologists involved in basic research attempt to discover underlying mechanisms that govern how organisms work...
of English parentage. He is a co-founder of modern chronobiology
Chronobiology
Chronobiology is a field of biology that examines periodic phenomena in living organisms and their adaptation to solar- and lunar-related rhythms. These cycles are known as biological rhythms. Chronobiology comes from the ancient Greek χρόνος , and biology, which pertains to the study, or science,...
along with Jürgen Aschoff
Jürgen Aschoff
Jürgen Walther Ludwig Aschoff was a German physician, biologist and behavioral physiologist. Together with Erwin Bünning and Colin Pittendrigh, he is considered to be a co-founder of the field of chronobiology.-Life:...
and Erwin Bünning
Erwin Bünning
Dr Erwin Bünning was a German biologist. His pioneering research in botany and plant physiology resulted in several contributions in phototropism, phototaxis, differentiation, growth substances and even Tropical Forests...
.
Life
Colin Pittendrigh was born in 1918 in northeastern EnglandEngland
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
(today Tyne and Wear
Tyne and Wear
Tyne and Wear is a metropolitan county in north east England around the mouths of the Rivers Tyne and Wear. It came into existence as a metropolitan county in 1974 after the passage of the Local Government Act 1972...
) and received his first degree in botany
Botany
Botany, plant science, or plant biology is a branch of biology that involves the scientific study of plant life. Traditionally, botany also included the study of fungi, algae and viruses...
at King's College, Newcastle upon Tyne, University of Durham, now University of Newcastle upon Tyne
University of Newcastle upon Tyne
Newcastle University is a major research-intensive university located in Newcastle upon Tyne in the north-east of England. It was established as a School of Medicine and Surgery in 1834 and became the University of Newcastle upon Tyne by an Act of Parliament in August 1963. Newcastle University is...
. He married and had two children, Robin and Colin Jr. (Sandy). During World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
the British Government sent him to Trinidad
Trinidad
Trinidad is the larger and more populous of the two major islands and numerous landforms which make up the island nation of Trinidad and Tobago. It is the southernmost island in the Caribbean and lies just off the northeastern coast of Venezuela. With an area of it is also the fifth largest in...
, where he studied the epidemiology
Epidemiology
Epidemiology is the study of health-event, health-characteristic, or health-determinant patterns in a population. It is the cornerstone method of public health research, and helps inform policy decisions and evidence-based medicine by identifying risk factors for disease and targets for preventive...
of malaria
Malaria
Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...
transmitted by mosquitoes breeding in the bromeliad ponds ("tanks" formed by overlapping leaves), making acute observations on bromeliad distribution within forest canopies and between contrasting forest formations. His work with the biting rhythms of these mosquitoes piqued his interest in biological rhythms.
After the war, Pittendrigh attended Columbia University
Columbia University
Columbia University in the City of New York is a private, Ivy League university in Manhattan, New York City. Columbia is the oldest institution of higher learning in the state of New York, the fifth oldest in the United States, and one of the country's nine Colonial Colleges founded before the...
to study for his Ph.D.
Ph.D.
A Ph.D. is a Doctor of Philosophy, an academic degree.Ph.D. may also refer to:* Ph.D. , a 1980s British group*Piled Higher and Deeper, a web comic strip*PhD: Phantasy Degree, a Korean comic series* PhD Docbook renderer, an XML renderer...
under the evolutionary geneticist Theodosius Dobzhansky
Theodosius Dobzhansky
Theodosius Grygorovych Dobzhansky ForMemRS was a prominent geneticist and evolutionary biologist, and a central figure in the field of evolutionary biology for his work in shaping the unifying modern evolutionary synthesis...
. In 1947 he joined the faculty at Princeton
Princeton University
Princeton University is a private research university located in Princeton, New Jersey, United States. The school is one of the eight universities of the Ivy League, and is one of the nine Colonial Colleges founded before the American Revolution....
, where he began his work on on circadian rhythm
Circadian rhythm
A circadian rhythm, popularly referred to as body clock, is an endogenously driven , roughly 24-hour cycle in biochemical, physiological, or behavioural processes. Circadian rhythms have been widely observed in plants, animals, fungi and cyanobacteria...
. He became a U.S. citizen in 1950; in 1969 he joined the faculty of Stanford where he helped found the program in Human Biology and later became the director of the Hopkins Marine Station
Hopkins Marine Station
Hopkins Marine Station is the marine laboratory of Stanford University. It is located ninety miles south of the university's main campus, in Pacific Grove, California on the Monterey Peninsula, adjacent to the Monterey Bay Aquarium. It is home to nine research laboratories and a fluctuating...
. He died of cancer on March 19, 1996 in his home in Bozeman, Montana
Bozeman, Montana
Bozeman is a city in and the county seat of Gallatin County, Montana, United States, in the southwestern part of the state. The 2010 census put Bozeman's population at 37,280 making it the fourth largest city in the state. It is the principal city of the Bozeman micropolitan area, which consists...
. His favorite hobby was fly-fishing.
Work
After his work in Trinidad, he continued to pursue his interest in animals' orientation to time at Princeton University. Together with Jürgen AschoffJürgen Aschoff
Jürgen Walther Ludwig Aschoff was a German physician, biologist and behavioral physiologist. Together with Erwin Bünning and Colin Pittendrigh, he is considered to be a co-founder of the field of chronobiology.-Life:...
he laid the groundwork for today's understanding of chronobiology
Chronobiology
Chronobiology is a field of biology that examines periodic phenomena in living organisms and their adaptation to solar- and lunar-related rhythms. These cycles are known as biological rhythms. Chronobiology comes from the ancient Greek χρόνος , and biology, which pertains to the study, or science,...
; investigating such topics as human wake/sleep cycles
Circadian rhythm
A circadian rhythm, popularly referred to as body clock, is an endogenously driven , roughly 24-hour cycle in biochemical, physiological, or behavioural processes. Circadian rhythms have been widely observed in plants, animals, fungi and cyanobacteria...
, hibernation
Hibernation
Hibernation is a state of inactivity and metabolic depression in animals, characterized by lower body temperature, slower breathing, and lower metabolic rate. Hibernating animals conserve food, especially during winter when food supplies are limited, tapping energy reserves, body fat, at a slow rate...
, the navigation
Navigation
Navigation is the process of monitoring and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks...
of animals, and jetlag. Pittendrigh became close friends with Aschoff when the latter visited the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
in 1958. Aschoff's visit inspired the two to organize the 1960 Cold Spring Harbor
Cold Spring Harbor Laboratory
The Cold Spring Harbor Laboratory is a private, non-profit institution with research programs focusing on cancer, neurobiology, plant genetics, genomics and bioinformatics. The Laboratory has a broad educational mission, including the recently established Watson School of Biological Sciences. It...
symposium, which marked the recognition of the new field of chronobiology.
Pittendrigh also established the concept of teleonomy
Teleonomy
Teleonomy is the quality of apparent purposefulness and of goal-directedness of structures and functions in living organisms that derive from their evolutionary history, adaptation for reproductive success, or generally, due to the operation of a program....
, a quality determined through objective principles as described in the book Behavior and Evolution (1958, edited by Anne Roe and George Gaylord Simpson). A teleonomic act or characteristic is one which owes its usefulness to the workings of a program. Pittendrigh applied this concept to knowledge of cellular control mechanisms. He purposefully positioned his concept of teleonomy against the concept of teleology
Teleology
A teleology is any philosophical account which holds that final causes exist in nature, meaning that design and purpose analogous to that found in human actions are inherent also in the rest of nature. The word comes from the Greek τέλος, telos; root: τελε-, "end, purpose...
, which he believed to be an unscientific and idealistic approach to the interpretation of biological control mechanisms.
Contributions to chronobiology
Pittendrigh was influential in establishing many of the key criteria a biological systemBiological system
In biology, a biological system is a group of organs that work together to perform a certain task. Common systems, such as those present in mammals and other animals, seen in human anatomy, are those such as the circulatory system, the respiratory system, the nervous system, etc.A group of systems...
must have in order to be considered a biological clock. His work studying the eclosion rhythms of Drosophila pseudoobscura
Drosophila pseudoobscura
Drosophila pseudoobscura is a species of fruit fly, used extensively in lab studies of speciation.In 2005, D. pseudoobscura was the second Drosophila species to have its genome sequenced, after the model organism Drosophila melanogaster....
demonstrated that 1) eclosion rhythms persist without environmental cues (i.e. in constant conditions), 2) unlike most chemical reactions, the period of eclosion remains relatively constant when exposed to changes in ambient temperature ("temperature compensation"), and 3) eclosion rhythms can be entrained
Entrainment (chronobiology)
Entrainment, within the study of chronobiology, occurs when rhythmic physiological or behavioral events match their period and phase to that of an environmental oscillation. A common example is the entrainment of circadian rhythms to the daily light–dark cycle, which ultimately is determined by...
by light cycles that are close to the flies' natural period.
Beginning in 1958, Pittendrigh developed the concept of the phase response curve
Phase response curve
A phase response curve illustrates the transient change in the cycle period of an oscillation induced by a perturbation as a function of the phase at which it is received...
or PRC. The PRC allowed chronobiologists to predict how a biological system would be affected by a change in its light schedule. Although biologists, including Pittendrigh himself, acknowledge that the PRC is a simplified model, it is still used today to teach the concept of non-parametric entrainment (see below).
Pittendrigh and Aschoff proposed two different models for the entrainment of the biological clock to external light cycles. Aschoff, noting that the internal clock's period depends on the length of the day, began with a parametric model in which the period of the internal clock shortens or lengthens in order to align with the external period. Pittendrigh's research with pulses of light and PRCs led him to propose a non-parametric model of entrainment in which pulses of light instantaneously shift the phase
Phase (waves)
Phase in waves is the fraction of a wave cycle which has elapsed relative to an arbitrary point.-Formula:The phase of an oscillation or wave refers to a sinusoidal function such as the following:...
of the biological clock, while the intrinsic period remains constant.
Evidence for Pittendrigh's model was presented in his 1976 paper, "A Functional Analysis of Circadian Pacemakers in Nocturnal Rodents," written in collaboration with Serge Daan
Serge Daan
Serge Daan is a Dutch scientist, known for his significant contributions to the field of Chronobiology.-Early life and education:Serge Daan was born in a wind mill, grew up in the Dutch countryside, and went to high school in Deventer...
. They showed that significant phase advances and delays could be induced in nocturnal rodents simply through the application of a single 15-minute light pulse at specific times of the rodents’ subjective night. Pittendrigh and Daan also demonstrated the history dependence of free running period, or the effects of prior light conditions on free running period in constant darkness (DD). Part II of the paper also develops certain observations regarding PRCs; Pittendrigh and Daan put forth that range of entrainment can be predicted by examination of the largest delay and the largest advance on a PRC. PRCs were found to have similar advance and delay zones, across species. However, species with a longer wake-sleep period tended to have larger advance zones as compared to delay zones whereas species with relatively short wake-sleep periods were found to have larger delay zones as compared to advance zones. Moreover, Pittendrigh and Daan argued that pacemaker accuracy was greater than rhythm accuracy. Part III demonstrated that various chemical stimuli can affect the period of mice, in this case ingestion of D2O causes the period to lengthen by up to 1.8 hours. D2O was later shown to lengthen the period of cockroaches as well. The use of chemicals to affect circadian periods and oscillations has led to the production of many new pharmaceutical drugs that aim to treat a variety of sleeping disorders. In part IV, Pittendrigh and Daan expanded their model to a two-pulse system (or “skeleton photoperiod”) with one flash at dawn and one at dusk to account for differences in day lengths. This model accurately predicts entrainment for photoperiods up to 12 hours, after which point a “Psi Jump” occurs (the organism switches which pulse is dawn and dusk). From these experiments, the concept of bistability was derived, showing that organisms are able to stably entrain to two different skeleton photoperiods each with a different phase relationship. In part V of the paper, "Pacemaker Structure: A Clock for All Seasons", Pittendrigh and Daan reported the phenomenon of alpha-splitting, in which animals develop two bouts of activity per 24 hour cycle, instead of one, in constant light (LL). Following these observations, they proposed a dual oscillator model, in which the pacemaker is composed of two mutually coupled oscillators, E and M, which regulate evening and morning activity peaks, respectively.
Timeline of accomplishments
- 1940: Graduation from University of Durham in England
- 1940-1945: Stationed in Trinidad working on Malaria for the Rockefeller FoundationRockefeller FoundationThe Rockefeller Foundation is a prominent philanthropic organization and private foundation based at 420 Fifth Avenue, New York City. The preeminent institution established by the six-generation Rockefeller family, it was founded by John D. Rockefeller , along with his son John D. Rockefeller, Jr...
- 1945-1946: Doctoral thesis at Columbia University (Graduated 1948)
- 1947: Assistant Professor of Biology at Princeton University
- 1950: Became U.S. citizen
- 1960: Chaired organizing committee for Cold Spring Harbor Symposium on biological clocks
- 1969: Began his work at Stanford University
- 1976-1984: Director of the Hopkins Marine StationHopkins Marine StationHopkins Marine Station is the marine laboratory of Stanford University. It is located ninety miles south of the university's main campus, in Pacific Grove, California on the Monterey Peninsula, adjacent to the Monterey Bay Aquarium. It is home to nine research laboratories and a fluctuating...
Positions and honors
- Member of Senior Staff of NASANASAThe National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
- National Academy of Sciences study: "Biology and the Exploration of Mars"
- National Academy of SciencesUnited States National Academy of SciencesThe National Academy of Sciences is a corporation in the United States whose members serve pro bono as "advisers to the nation on science, engineering, and medicine." As a national academy, new members of the organization are elected annually by current members, based on their distinguished and...
- American Academy of Arts and SciencesAmerican Academy of Arts and SciencesThe American Academy of Arts and Sciences is an independent policy research center that conducts multidisciplinary studies of complex and emerging problems. The Academy’s elected members are leaders in the academic disciplines, the arts, business, and public affairs.James Bowdoin, John Adams, and...
- Guggenheim FellowshipGuggenheim FellowshipGuggenheim Fellowships are American grants that have been awarded annually since 1925 by the John Simon Guggenheim Memorial Foundation to those "who have demonstrated exceptional capacity for productive scholarship or exceptional creative ability in the arts." Each year, the foundation makes...
- Alexander von Humboldt PrizeHumboldt PrizeThe Humboldt Prize, also known as the Humboldt Research Award, is an award given by the Alexander von Humboldt Foundation to internationally renowned scientists and scholars, and is currently valued at € 60,000 with the possibility of further support during the prize winner's life. Up to one...
- Gold Medal of the Czech Academy of Science
- Director of the Hopkins Marine StationHopkins Marine StationHopkins Marine Station is the marine laboratory of Stanford University. It is located ninety miles south of the university's main campus, in Pacific Grove, California on the Monterey Peninsula, adjacent to the Monterey Bay Aquarium. It is home to nine research laboratories and a fluctuating...
- President of the American Society of NaturalistsAmerican Society of NaturalistsThe American Society of Naturalists was founded in 1883 and is one of the oldest professional societies dedicated to the biological sciences in North America...
- Vice-President of the American Association for the Advancement of ScienceAmerican Association for the Advancement of ScienceThe American Association for the Advancement of Science is an international non-profit organization with the stated goals of promoting cooperation among scientists, defending scientific freedom, encouraging scientific responsibility, and supporting scientific education and science outreach for the...