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Circadian clocks in crustaceans: identified neuronal and cellular systems
Circadian clocks in crustaceans: identified neuronal and cellular systems

... physiological and behavioural events in an oscillatory pattern. As in many other animal taxa (52), such oscillators are mainly located in the nervous system of crustaceans (20, 21). The core concept of the biological clock builds upon autonomously oscillating neurons or sets of neurons showing circa ...
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Physiology of the Mammalian Circadian System
Physiology of the Mammalian Circadian System

... THE SUPRACHIASMATIC NUCLEUS, “STILL” THE MASTER CIRCADIAN PACEMAKER IN MAMMALS As described later in this chapter, exciting new results demonstrating that the molecular circadian clock exists in many tissues and organs are revolutionizing our understanding of how the circadian clock system is organi ...
highlighted topics - American Journal of Physiology
highlighted topics - American Journal of Physiology

... continues to run unperturbed in the presence of tetrodotoxin, which blocks these action potentials (75, 88). Because electrical discharge represents one of the pacemaker’s outputs and because the nature of the coupling between the circadian pacemaker and firing rate is not known, there may be some e ...
Using light to tell the time of day: sensory coding in the mammalian
Using light to tell the time of day: sensory coding in the mammalian

... middle-wavelength (‘green-yellow’) light at negative solar angles. (B) Sensitivity profiles of the four visual opsin proteins responsible for photoreception in mice, illustrating the distinction between colour and brightness: monochromatic light at 365 and 582 nm produces identical activation of mou ...
Circadian Organization in Hemimetabolous Insects
Circadian Organization in Hemimetabolous Insects

... rhythm, the bilaterally paired clocks form a functional unit. They interact to produce a stable time structure within individual insects by exchanging photic and temporal information through neural pathways, in which serotonin and pigment-dispersing factor (PDF) are involved as chemical messengers. ...
Introduction 9 INTRODUCTION Circadian rhythms in physiology and
Introduction 9 INTRODUCTION Circadian rhythms in physiology and

... is located in the suprachiasmatic nuclei (SCN) at the base of the hypothalamus. First indications were provided in 1972, when it was shown that lesions of the SCN abolish the adrenal corticosterone rhythm, as well as rhythms in drinking and locomotor activity. In 1990, it was demonstrated that trans ...
Biological Rhythms
Biological Rhythms

... joined, CLK-CYC produce two other proteins, PERIOD and TIME (PER-TIM). PERTIM has the effect of rendering the CLK-CYC proteins inactive, so that, as PERTIM increases, CLK-CYC decreases and therefore PER-TIM starts to decrease too (negative feedback). This loop takes about 24 hours and, hey presto, y ...
Biological Rhythms
Biological Rhythms

... joined, CLK-CYC produce two other proteins, PERIOD and TIME (PER-TIM). PERTIM has the effect of rendering the CLK-CYC proteins inactive, so that, as PERTIM increases, CLK-CYC decreases and therefore PER-TIM starts to decrease too (negative feedback). This loop takes about 24 hours and, hey presto, y ...
J.H. Meijer, S. Michel, M.J. Vansteensel
J.H. Meijer, S. Michel, M.J. Vansteensel

... and a bright night. Instead, the cells are equipped to differentiate only between day and night. The large range of illumination levels in the environment is translated into an electrical activity signal, indicating light intensities occurring around dawn and dusk. The intensity–response function is ...
Entrainment	of	the	Fetal	Circadian	Clock	by	Temperature	Cycles
Entrainment of the Fetal Circadian Clock by Temperature Cycles

... Fig. 6. The small circles and triangles indicate the 6ming of fetal SCN rhythms rela6ve to temperature cycles experienced in vitro. During the cycles, temperature was high at night (8PM to 8AM) or during the day (8AM to 8PM). Each symbol represents the 6ming for a single fetal SCN. A strong tem ...
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Colin Pittendrigh

Colin Pittendrigh (October 13, 1918 – March 19, 1996) was a British-born biologist who spent most of his adult life in the United States. Pittendrigh is regarded as the “father of the biological clock,” and founded the modern field of chronobiology alongside Jürgen Aschoff and Erwin Bünning. He is known for his careful descriptions of the properties of the circadian clock in Drosophila and other species, and providing the first formal models of how circadian rhythms entrain (synchronize) to local light-dark cycles.He obtained his first degree of botany at University of Durham, and was assigned to wartime service as a biologist in Trinidad during World War II where he studied malaria transmission by mosquitoes. After the war, he attended Columbia University to study for his Ph.D. He later joined the faculty of Princeton University and started his chronobiology research. He also co-chaired a Mars exploration project at NASA from 1964 to 1966.The defining principle that Pittendrigh developed throughout his career was that the properties of the circadian clock are independent from those of the behaviors it controls. This gave him the freedom to study the clock through a range of physiological functions from the hatching of fruit flies to rodents' locomotor activities. He performed large series of experiments to demonstrate that circadian rhythmicity is intrinsic and independent of environmental cues. He carried out a famous and protracted debate with Frank Brown, of Northwestern University, on whether circadian timekeeping is intrinsic or environmentally driven. Pittendrigh’s data and argument ultimately prevailed and sparked interest in chronobiology.Pittendrigh died from cancer on Tuesday, March 19, 1996, at his home in Bozeman, Montana. He has been regarded as one of the most influential figures in the field, and his research influences the field of chronobiology even after his death. The Society for Research on Biological Rhythms holds biannual lectures named in honor of Pittendrigh and Aschoff.
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