Jürgen Aschoff

This article covers the biologist and behavioral physiologist; on neurologists and alternative physicians, see Jürgen C. Aschoff .

Jürgen Walther Ludwig Aschoff (born January 25, 1913 in Freiburg im Breisgau , † October 12, 1998 ibid) was a German physician and behavioral physiologist ; together with Erwin Bünning and Colin Pittendrigh founders of chronobiology .

Life

Jürgen Aschoff was born as the fifth child of the pathologist Ludwig Aschoff ( Aschoff-Tawara node ) and his wife Clara. After graduating from a humanistic grammar school, he studied - according to his own statement, "[m] angels specific interest" - medicine at the University of Bonn , where he joined the Alemannia Bonn fraternity . After graduating in 1937 at the University of Freiburg , he was there a year later with the thesis blood alcohol curve and getting used to the Dr. med. PhD .

Aschoff then worked at the Physiological Institute of the University of Göttingen and on October 26 and 27, 1942, took part in the conference on medical issues in distress and winter death, where a lecture was also given on the "hypothermia experiments" in the Dachau concentration camp . He completed his habilitation in 1944. On September 1, 1947, he became a lecturer and acting head of the Physiological Institute at the University of Würzburg at Röntgenring 9. Two years later he took up his first professorship at the University of Göttingen as a physiologist .

From 1952 he worked at the Max Planck Institute for Medical Research in Heidelberg . From 1967 to 1979 he was Director at the Max Planck Institute for Behavioral Physiology in Seewiesen ( Andechs site ) and Scientific Member of the Max Planck Society . During the time in Seewiesen he was an adjunct professor in Munich. He was also a Senator of the Max Planck Society from 1972 to 1976. He had been a member of the Leopoldina Scholars' Academy since 1978, and was a full member of the mathematics and natural sciences class of the Bavarian Academy of Sciences from 1984 to 1987, and after moving to Freiburg in 1987 he was a corresponding member.

After his retirement in 1983 and after moving back to Freiburg in 1987, Aschoff continued his scientific work in the form of further publications. Jürgen Aschoff died 10 months after his wife after a brief illness at the age of 85.

Act

He made his early publications in the field of physiology on thermoregulation . Almost inevitably, Aschoff found a 24-hour rhythm of body temperature fluctuations in his research on human body temperature (including his own investigations ). But as a "lone wolf", as he called himself, he had no contact with other scientists who dealt with these phenomena. He was also unfamiliar with the free-range rhythms in plants. Aschoff once said that botanists were 103 years ahead of zoologists when it came to the discovery of the circadian rhythm .

In 1953 Aschoff met Erwin Bünning , one of the first chronobiologists . The relationship between the two was amicable. In 1958, Aschoff and Colin Pittendrigh met and remained lifelong friends. Aschoff, Bünning and Pittendrigh were the main initiators of the " Cold Spring Harbor Symposium for Biological Clocks" in 1960 . Here they laid the virtual foundation for biological rhythms research in the 20th century.

In 1954 Aschoff and Gustav Kramer , who had discovered the sun compass orientation in birds, met for the first time. In 1958 Konrad Lorenz and Erich von Holst brought Aschoff to Seewiesen. From Erich von Holst he learned a lot about the coupling of oscillators and the phenomenon of relative coordination. A short time later, Aschoff took over a department of the Max Planck Institute for Behavioral Physiology in Erling-Andechs, which was newly founded for him , so that physiological research was actually carried out there in addition to the “classic” and rather descriptive ethology .

Shortly after Aschoff was appointed director of the Max Planck Institute for Behavioral Physiology in Andechs, Rütger Wever and Eberhard Gwinner also began to work in Andechs. Over the years, the institute developed into the Mecca of chronobiology.

Many scientists from all over the world came to Andechs to work with Aschoff, including Colin Pittendrigh and Serge Daan . Here they found excellent equipment and - unique in the world - the "bunker", an isolation facility dug into the mountain for research into human and animal circadian rhythms. The bunker was built with the help of NATO in the early 1960s.

Scientific work

After he had come across the 24-hour rhythm in human temperature regulation in his own experiments, Aschoff's interest in the underlying mechanisms grew. He began to make further experiments on this subject. So he raised birds by hand and observed several generations of mice that he bred under constant conditions in the laboratory. After these attempts he postulated:

• "The rhythm is innate, and it does not require exposure to a 24-hour day to generate it."

He continued his work by studying the effects of exogenous stimuli on the endogenous circadian system in birds and humans . The intensity of continuous lighting modulated the frequency predictably, even if in nocturnal (nocturnal) and diurnal animals in the opposite direction - a phenomenon that was soon generalized as "Aschoff's Rule":

• The free-running period tau (τ) in nocturnal animals is longer in L: L than in D: D, whereas in diurnal animals tau in L: L is shorter than in D: D where L: L = 24 hours of light and D: D = Means 24 hours of darkness

These and other results led to a new conceptual look at the synchronization of circadian rhythms. He postulated an innate , biological oscillator , which is synchronized in a natural environment, for example by the day-night change. He called the synchronizing factor "timer", a word that has also found its way into the English language.

Using the physical oscillator theory, Aschoff was able to make predictions about the behavior of circadian systems and their response to different timers. His experimental and theoretical work in the 1950s and 1960s laid the foundation for today's view of circadian rhythms as a product of endogenous oscillators and their constant phase relationship to the light-dark cycle - the most precise timer the earth has to offer.

Aschoff and Wever were able to establish the well-founded theory that human physiology and behavior are just as controlled by endogenous circadian oscillators as is that of animals. This finding had far-reaching effects in biology and medicine. It led to our current understanding of many socio-medical problems such as those resulting from shift work , affective disorders , sleep disorders , aging and jet lag . It also laid the basis for optimizing pharmacological therapies .

Fonts (selection)

• With Rütger Wever: beginning and end of the daily activity of wild birds. In: Journal of Ornithology . Vol. 103 (1962), H. 1, pp. 2-27, doi: 10.1007 / BF01670845 .
• Ed .: Circadian Clocks: proceedings of the Feldafing Summer School, 7-18 September 1964. North-Holland, Amsterdam 1965.
• Desynchronization and Resynchronization of Human Circadian Rhythm. In: Aerospace medicine. Vol. 40, H. 8 (August 1969), pp. 844-849, PMID 5803983 .
• With Rütger Wever: The Circadian System of Man. In: Biological Rhythms. 1981, pp. 311-331, doi: 10.1007 / 978-1-4615-6552-9 17 .

literature

• Eberhard Gwinner : Jürgen Aschoff: January 25, 1913– October 12, 1998. In: Yearbook of the Max Planck Society. Vandenhoeck & Ruprecht, Göttingen 1999, ISBN 3-525-86129-X , p. 901 ff.
• Eberhard Gwinner: Jürgen Aschoff (1913–1998). In: Journal of Ornithology. 140: 384-387 (1999).
• Ernst Klee : The dictionary of persons on the Third Reich . Who was what before and after 1945 . 2nd Edition. Fischer-Taschenbuch-Verlag, Frankfurt am Main 2007, ISBN 978-3-596-16048-8 .
• Serge Daan : The human internal clock. Jürgen Aschoff (1913–1998), scientist in an eventful century. Reichert Verlag, Wiesbaden 2017, ISBN 978-3-95490-310-8

Web links

• Literature by and about Jürgen Aschoff in the catalog of the German National Library

Individual evidence

1. ^ Ernst Klee: The dictionary of persons on the Third Reich. Frankfurt am Main 2007, p. 20.
2. ↑ Julius Maximilians University of Würzburg: Lecture directory for the summer semester of 1948. University printing house H. Stürtz, Würzburg 1948, pp. 11 and 21.