The Committee on the International Prize for Biology
of Japan Society for the Promotion of Science
awards the 2006 International Prize for Biology
in the field of “Chronobiology”
Dr. Serge DAAN,
Niko Tinbergen Chair in Behavioral Biology,
University of Groningen, The Netherlands
On Thursday, September 7, 2006, the Committee on the International Prize for Biology (chaired by Dr. Saburo Nagakura, President of the Japan Academy) of the Japan Society for the Promotion of Science decided to present the 22nd (2006) International Prize for Biology to Dr. Serge Daan, a Netherlands citizen who is Niko Tinbergen Chair in Behavioral Biology, The University of Groningen, The Netherlands. The field of specialization for the 22nd Prize is “Chronobiology.”
Process of Selection
The Selection Committee composed of a chair (Dr. Motonori Hoshi, professor emeritus, Tokyo Institute of Technology) and 18 other members, including four overseas members, functioned as a sub-committee of the Committee on the International Prize for Biology. It sent out invitations for candidate nominations to Japanese and overseas universities, research institutions, academic societies and individual experts in the subject field of specialization. Altogether these comprised 1,794 mailing addresses. 68 nominations were received by the deadline. After adjustment for overlapping nominations, there were nominations for 31 individuals who reside in 14 countries spread throughout the world. Upon careful deliberation of the nominees at its first through fourth meetings, the Selection Committee decided to recommend Dr. Daan as the nominee for the 2006 Prize. Thereafter, the Committee on the International Prize for Biology formally endorsed the Selection Committee’s recommendation.
Achievements Recognized by the Award
Conducting detailed observations and investigations using rodent behavior as an indicator, Dr. Daan elucidated the basic properties of circadian rhythm and its role in behavior expression and physiological phenomena. By formulating models based on these findings, he succeeded in explaining the underlying mechanisms of rhythmicity, thereby laying the foundations of chronobiology.
In this work, Dr. Daan conducted both empirical and theoretical analyses on virtually all the important properties of circadian rhythms and their adaptive significance. Among the questions he investigated were the mechanism by which circadian rhythm is synchronized to light-dark cycle (entrainment) and its ecological significance; the after-effects of entrainment; seasonal adaptation; and a regulatory mechanism for bimodal rhythms (those with dawn and dusk activity peaks) which involves separate morning and evening (M-E) oscillators. The five papers in which these findings were published in the Journal of Comparative Physiology in 1976 are now regarded as classics in the field of Chronobiology and are required reading for every scientist who studies biological clocks.In particular, the M-E two-oscillator model proposed in these papers renders a masterful explanation of the diurnal cycle of circadian rhythms, seasonal adaptation, and photoperiodic response, so it has been highly influential in all subsequent research on the clock mechanism.
In his work on human sleep, Dr. Daan contributed to our understanding of the human sleep rhythm by demonstrating that sleep duration is determined by fluctuations in sleep-regulating variables between the upper and lower thresholds of the sleep rhythm, whose range is entrained to the circadian rhythm. His research on animal hibernation changed the accepted view of a phenomenon long believed to be similar to sleep, demonstrating that hibernation is in fact a kind of sleep deprivation.
Further, Dr. Daan was one of the first researchers to focus on the ecological significance of annual cycles and related circadian rhythms from the viewpoint of ecological energetics. By analyzing the temporal organization of a predator-prey system, the kestrel and the common vole, he showed that, for both predators and prey, daily habits have survival value. In an analysis of the timing and success rate of reproduction in kestrels, he showed that reproductive timing is tuned to stored energy resources in the female. These studies made a profound contribution to understanding the adaptive significance of circadian rhythms and seasonality.
These many research breakthroughs, which have contributed greatly to the advancement of Chronobiology, make Dr. Daan a worthy recipient of the International Prize for Biology.
Ceremony and Commemorative Symposium
The award ceremony was convened on Monday, November 20, 2006, at the Japan Academy (7-32 Ueno Koen, Taito-ku, Tokyo). This year for the first time, an after-ceremony lecture open to the public was held to celebrate the award presentation on November 28, 2006. At it, Dr. Daan offered in layman’s language an introduction to Chronobiology, giving the attentive public a deeper understanding of the workings of biology in people’s everyday lives.
To commemorate the award to Dr. Daan, an International Prize for Biology Commemorative Symposium on Chronobiology was convened on December 1 and 2, 2006, at the Tokyo International Forum.
|DATE OF BIRTH :
||June 11, 1940
||Kingdom of the Netherlands
||Niko Tinbergen Chair in Behavioral Biology,
University of Groningen, The Netherlands
HONORS AND AWARDS
||Annual Award, Victor & Erna Hasselblad Foundation, Sweden
||8th Laurence Irving-Per Scholander Memorial Lecturer, Institute of Arctic Biology, University of Alaska
||Prize from the Dutch Society for Light Therapy
||Alexander von Humboldt Forschungspreis (Research Prize), Germany
||Hollandse Maatschappij der Wetenschappen (Dutch Society of Sciences)
||Royal Society of Canada, elected Foreign Fellow
||Ridder in de Orde van de Nederlandse Leeuw (Knight in the Order of the Dutch Lion)
Dr. Daan has pursued comparative ethological studies of circadian rhythms in a wide variety of animal species, from mice and birds to humans, focusing on rhythms of behavior, sleep and waking. His perspective encompasses not only the mechanism of circadian rhythms but also a deep understanding of their ecological significance, that is, the role of cyclic activity patterns in relation to fitness and survival value. In keeping with the breadth of his interests, Dr. Daan’s methodology has not been limited to the laboratory but has extended also to field studies and experiments.
Research on circadian rhythms in rodents
With Dr. Colin Pittendrigh, Dr. Daan conducted detailed observations and investigations of circadian rhythms in rodents, using behavior as an indicator. Their work determined the basic properties and fundamental role of circadian rhythms in behavior and physiology; further, they established a research methodology in this field by using their results to formulate a model capable of explaining the underlying mechanism.
This work led Dr. Daan to propose the concept of the circadian system and to arrive at an empirical and theoretical analysis of almost all the important properties of the circadian system in rodents, together with their adaptive significance. Among the questions he investigated were the mechanism by which the circadian rhythm is synchronized to the light-dark cycle (entrainment) and its ecological significance, the after-effects of entrainment, seasonal adaptation, and a regulatory mechanism for bimodal rhythms (those with dawn and dusk activity peaks) which involves separate Morning and Evening (M-E) oscillators.
These findings were published in 1976 as five papers, co-authored with Dr. Colin Pittendrigh, in the Journal of Comparative Physiology. Today these are regarded as classic papers in chronobiology, and they are required reading for every scientist who studies biological clocks. The M-E two-oscillator model was particularly innovative; it provides an elegant explanation for the diurnal cycle of circadian rhythms, their seasonal adaptation, and photoperiodic response, and to this day it remains an influential paradigm in circadian system research, not only in mammals but also in insects such as the fruit fly Drosophila melanogaster. The dual oscillator model has led to the recent discoveries of a region in the suprachiasmatic nucleus in mammals which responds to the M-E oscillators, and of neurons which have a similar response in the brain of Drosophila. Dr. Daan himself has examined this question in various species. He recently proposed that the M-E oscillators may be driven by separate clock genes, and he is currently studying this hypothesis using animals in which the relevant genes have been knocked out.
Research on sleep regulation
Dr. Daan proposed a “two-process model” of human sleep regulation, in which sleep is regulated both by a circadian rhythm and by sleep-regulating variables. According to this model, the sleep-regulating variables increase with accumulating fatigue or decreasing bodily functions during wakefulness, until an upper threshold is reached and sleep is induced; during sleep the variables decrease until they reach a lower threshold and waking results. Further, the level of the range between these sleep-wake thresholds oscillates with a cycle of approximately 24 hours, regulated by a circadian pacemaker; thus, the timing and duration of sleep are regulated by this pacemaker. This is the most powerful model yet obtained for explaining human sleep rhythms, and its predictions have been extensively validated by experiments. The model has also contributed to the treatment of seasonal depression and to light therapy for jet lag.
In ecological studies of annual cycles in hibernating animals, Dr. Daan discovered that the need for sleep increases during hibernation, and that hibernators must wake periodically from torpor in order to sleep. Thus Dr. Daan changed the prevailing idea of these winter states as being similar to sleep, demonstrating instead that hibernation actually has a sleep-deprivation effect.
Ecological research on circadian rhythms
Dr. Daan was one of the first to focus on the ecological significance of circadian rhythms. Analyzing the temporal structure of a predator-prey system, the kestrel and the common vole, he showed that the temporal organization of flight-hunting in the kestrel is separate from that of the need to feed, with the peak flight-hunting frequency depending on the daily peak hunting success rate and the activity peak of the prey; he also showed that the voles vary their hours of activity in response to predation. These findings demonstrated that, for both predator and prey, daily habits have survival value. In an analysis of the timing and success rate of reproduction in the kestrel, he showed that reproductive timing is tuned to the storage of energy resources in the female. Through these studies, Dr. Daan contributed greatly to the understanding of the adaptive significance of circadian rhythms and seasonality.
Through these multifaceted approaches, both experimental and theoretical, Dr. Daan has continued to make major contributions to the field of chronobiology from its genesis to the present day.
- S.DAAN and J.ASCHOFF: Circadian Rhythms of Locomotor Activity in Captive Birds and Mammals: Their Variations with Season and Latitude. Oecologia 18: 269-316 (1975)
- C.S.PITTENDRIGH and S.DAAN: A Functional Analysis of Circadian Pacemakers in Nocturnal Rodents. I-V. J.comp.Physiol. 106: 223-355 (1976)
- R.H.DRENT and S.DAAN: The prudent parent: Energetic adjustments in avian breeding. Ardea 68: 225-252 (1980)
- S.DAAN: Adaptive daily strategies in behaviour. In: J.ASCHOFF (ed.): Handbook of Behavioral Neurobiology, vol. 4, Biological Rhythms. Chapter 15, 275-298 (1981) Plenum Press, New York
- J.ASCHOFF, S.DAAN and G. GROOS (eds): Vertebrate Circadian Systems: Structure and Physiology, pp. 13-24, Springer Verlag, New York (1982)
- S.DAAN, D.G.M.BEERSMA and A.A.BORBÉLY: Timing of human sleep: re¬covery process gated by a circadian pacemaker. Am.J.Physiol. 246: R161-R178 (1984)
- S.DAAN and A.J.LEWY: Scheduled exposure to daylight: A potential strategy to reduce ‘Jet lag’ following transmeridian flight. Psychopharmacology Bulletin 20: 566-568 (1984)
- S.DAAN and E.GWINNER (eds.) Biological Clocks and Environmental Time. Proceedings of a symposium held in honour of Prof.Dr.Juergen Aschoff. Guilford Press, New York. pp 1-192 (1989)
- S.DAAN, D.MASMAN and A.GROENEWOLD: Avian basal metabolic rates: Their association with body composition and parental energy expenditure. Am.J.Physiol. 259: R333-340 (1990)
- S.DAAN, C.DIJKSTRA and J.M.TINBERGEN: Family planning in the kestrel: The ultimate control of covariation in laying date and clutch size. Behaviour 114:83-116 (1990).
- S.DAAN, B.BARNES and A.M.STRIJKSTRA: Warming up for sleep ? Ground squirrels sleep during arousals from hibernation. Neuroscience Letters 128:265-268 (1991).
- S.DAAN, C.DEERENBERG, C.DIJKSTRA: Increased daily work precipitates natural death in the Kestrel. J. Animal Ecology 65:539-544 (1996)
- S.DAAN, C. DIJKSTRA, F.J.WEISSING: An evolutionary explanation for seasonal trends in avian sex ratios. Behavioral Ecology 7:426-430 (1996)
- S.DAAN, J.M. TINBERGEN: Adaptation of life histories. In: J.R.Krebs & N.B.Davies, Behavioral Ecology. 4th Ed. Blackwell, pp. 311-333 (1997)
- C.DEERENBERG, V.APANIUS, S.DAAN, N.BOS: Reproductive effort decreases antibody responsiveness. Proc.roy.Soc.B 264:1021-1029 (1997)
- J.ASCHOFF, S.DAAN: On the estimation of long time intervals: dependence on the duration of wake time. In: Recent Advances in Physiological Anthropology. (M.Sato, H.Tokura, S. Watanuki, eds) Kyushu University Press pp 17-23 (1999)
- S.DAAN: Colin Pittendrigh, Jürgen Aschoff and the natural entrainment of circadian systems. J. biol. Rhythms15:195-207 (2000)
- S.DAAN, U.ALBRECHT, G.T.J.Van der HORST, H.ILLNEROVÁ, T.ROENNEBERG, T.A.WEHR, W.J.SCHWARTZ: Assembling a clock for all seasons: are there M and E oscillators in the genes ? J.biol.Rhythms 16:105-116 (2001)
- S.DAAN, J.ASCHOFF: The entrainment of circadian systems. Chapter 1 in: Handbook of Behavioral Neurobiology Vol. 12 Circadian Clocks. J.S.Takahashi, F.W.Turek, R.Y.Moore, eds. Kluwer/Plenum, New York pp 7-43 (2001)
- M.RÜGER, M.C.M.GORDIJN, D.G.M.BEERSMA, B.DE VRIES, S.DAAN: Acute and phaseshifting effects of ocular and extraocular light in human circadian physiology. J. biol. Rhythms 18:409-419 (2003)