The Experts below are selected from a list of 12870 Experts worldwide ranked by ideXlab platform
Toshio Fukuda - One of the best experts on this subject based on the ideXlab platform.
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Control of Biological Clock activity capsulated by lipid-mono-layer
2012 IEEE International Conference on Robotics and Automation, 2012Co-Authors: Masaru Kojima, Masahiro Nakajima, Michio Homma, Kingo Takiguchi, Takao Kondo, Toshio FukudaAbstract:In this paper, we try to establish new technique that the components of the Biological Clock are reconstituted into the liposome. In other words, we try to produce a nano size Clock, capsulated into the liposome, made by protein molecules. The circadian Clock is a basic cellular system found in almost all organisms. This Clock generates self-sustained oscillations under constant conditions with a ≈ 24-hour (circadian) period. In cyanobacteria, circadian Clock could be reconstituted in vitro only by mixing the three Clock proteins, KaiA, KaiB, KaiC, with adenosine triphosphate (ATP). So we reconstitute these proteins and adenosine triphosphate (ATP) into phospholipid-coated microdroplet and confirmed the Clock function. The Clocks in phospholipids-coated microdroplet indicate long period more than 24 hours. In this case, period length became 35 hour, self-sustaining oscillation was reaming with little dumping. To reveal why the time cycle became long period, we observed localization of Kai proteins in phospholipid-coated microdroplets by using fluorescents labeled Kai proteins under fluorescent (confocal) microscopy. From the observation of localization of Kai proteins, we found KaiB protein was distributed equivalently, on the other hand, KaiC protein was located near membrane of phospholipid-coated microdroplet. These results indicate that different localization between Kai proteins cause long period oscillation and we could control period length depend on calculation data from localization.
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Nano size Biological Clock capsulated by lipid layer: Reconstitution of Biological Clock into phospholipid-coated microdroplets
2009 9th IEEE Conference on Nanotechnology (IEEE-NANO), 2009Co-Authors: Masaru Kojima, Masae Ohno, Masahiro Nakajima, Michio Homma, Kingo Takiguchi, Takao Kondo, Toshio FukudaAbstract:We propose a nano size Clock, capsulated into micro size liposome, made by protein molecules. The circadian Clock is a basic cellular system found in almost all organisms. This Clock generates self-sustained oscillations under constant conditions with a ¿24-hour (circadian) period. In cyanobacteria, circadian Clock was reconstituted by only three proteins. We reconstitute these proteins and adenosine triphosphate (ATP; energy of Clock) into lipid layer and confirmed the Clock function. This system will reveal more detail about Biological Clock and bring application possibility.
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Reconstitution of Biological Clock into phospholipid-coated microdroplet
2009 International Symposium on Micro-NanoMechatronics and Human Science, 2009Co-Authors: Masaru Kojima, Masae Ohno, Masahiro Nakajima, Michio Homma, Kingo Takiguchi, Takao Kondo, Toshio FukudaAbstract:In this paper, we try to establish newly technique that the components of the Biological Clock are reconstituted into the liposome. In other words, we try to produce a nano size Clock, capsulated into the liposome, made by protein molecules. The Biological Clock is a basic cellular system found in almost all organisms. This Clock generates self-sustained oscillations under constant conditions with a ¿24-hour (circadian) period. Only three proteins in cyanobacteria reconstituted Biological Clock. We reconstitute these proteins and adenosine triphosphate (ATP) into phospholipid-coated microdroplet and confirmed the Clock function. This system will reveal more detailed about Biological Clock system and bring application possibility, such as drug delivery.
Ruud M. Buijs - One of the best experts on this subject based on the ideXlab platform.
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Vasopressin and the Output of the Hypothalamic Biological Clock
Journal of neuroendocrinology, 2010Co-Authors: Andries Kalsbeek, Ellen A. Fliers, M. A. Hofman, Dick F. Swaab, Ruud M. BuijsAbstract:The physiological effects of vasopressin as a peripheral hormone were first reported more than 100 years ago. However, it was not until the first immunocytochemical studies were carried out in the early 1970s, using vasopressin antibodies, and the discovery of an extensive distribution of vasopressin-containing fibres outside the hypothalamus, that a neurotransmitter role for vasopressin could be hypothesised. These studies revealed four additional vasopressin systems next to the classical magnocellular vasopressin system in the paraventricular and supraoptic nuclei: a sexually dimorphic system originating from the bed nucleus of the stria terminalis and the medial amygdala, an autonomic and endocrine system originating from the medial part of the paraventricular nucleus, and the circadian system originating from the hypothalamic suprachiasmatic nuclei (SCN). At about the same time as the discovery of the neurotransmitter function of vasopressin, it also became clear that the SCN contain the main component of the mammalian Biological Clock system (i.e. the endogenous pacemaker). This review will concentrate on the significance of the vasopressin neurones in the SCN for the functional output of the Biological Clock that is contained within it. The vasopressin-containing subpopulation is a characteristic feature of the SCN in many species, including humans. The activity of the vasopressin neurones in the SCN shows a pronounced daily variation in its activity that has also been demonstrated in human post-mortem brains. Animal experiments show an important role for SCN-derived vasopressin in the control of neuroendocrine day/night rhythms such as that of the hypothalamic-pituitary-adrenal and hypothalamic-pituitary-gonadal axes. The remarkable correlation between a diminished presence of vasopressin in the SCN and a deterioration of sleep-wake rhythms during ageing and depression make it likely that, also in humans, the vasopressin neurones contribute considerably to the rhythmic output of the SCN.
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light and diurnal cycle affect autonomic cardiac balance in human possible role for the Biological Clock
Autonomic Neuroscience: Basic and Clinical, 2004Co-Authors: Frank A J L Scheer, Lorenz J P Van Doornen, Ruud M. BuijsAbstract:The morning shift in cardiac sympatho-vagal balance seems involved in the increased risk of cardiovascular incidents at that time. To investigate the contribution of the Biological Clock in autonomic cardiac control, we investigated the presence of a diurnal rhythm independent of external factors, and of a circadian phase-dependent effect of moderate light in healthy volunteers. Recordings of heart rate (HR) and vagal and sympathetic cardiac tone were performed at different times over the day-night cycle during supine, awake, resting conditions, during exposure to different light intensities. The similarity between the diurnal rhythm in resting HR and that during previous constant routine conditions, demonstrated that our setup allowed accurate estimation of the endogenous circadian rhythm in HR. The present study suggests that, while a circadian rhythm in vagal cardiac tone is the main cause for the circadian rhythm in resting heart rate, the increase in sympathetic cardiac tone participates in the HR increase caused by early morning light.
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The Biological Clock: The Bodyguard of Temporal Homeostasis
Chronobiology international, 2004Co-Authors: Stephanie Perreau-lenz, Ruud M. Buijs, Paul Pévet, Andries KalsbeekAbstract:In order for any organism to function properly, it is crucial that it be table to control the timing of its Biological functions. An internal Biological Clock, located, in mammals, in the suprachiasmatic nucleus of the hypothalamus (SCN), therefore carefully guards this temporal homeostasis by delivering its message of time throughout the body. In view of the large variety of body functions (behavioral, physiological, and endocrine) as well as the large variety in their preferred time of main activity along the light:dark cycle, it seems logical to envision different means of time distribution by the SCN. In the present review, we propose that even though it presents a unimodal circadian rhythm of general electrical and metabolic activity, the SCN seems to use several sorts of output connections that are active at different times along the light: dark cycle to control the rhythmic expression of different body functions. Although the SCN is suggested to use diffusion of synchronizing factors in the rhythmi...
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the daily rhythm in plasma glucagon concentrations in the rat is modulated by the Biological Clock and by feeding behavior
Diabetes, 2003Co-Authors: Marieke Ruiter, Andries Kalsbeek, Susanne E La Fleur, Caroline Van Heijningen, Jan Van Der Vliet, Ruud M. BuijsAbstract:Plasma glucose concentrations display a daily rhythm generated by the hypothalamic Biological Clock, located in the suprachiasmatic nucleus (SCN). How the SCN orchestrates this rhythm is unknown. Because glucagon stimulates hepatic glucose production, we hypothesized that if glucagon has a daily rhythm, then it may be responsible for the glucose rhythm. From hourly blood samples, we determined daily glucagon concentrations for intact and SCN-lesioned rats. Intact ad libitum–fed rats showed a clear daily glucagon rhythm, and fasting resulted in an even more pronounced rhythm. It is interesting that a decrease in glucagon concentrations, instead of the expected increase, occurred already shortly after food removal. Toward the start of the active period, a peak in glucagon levels occurred, with concentrations similar to those measured in ad libitum– fed rats. SCN lesions abolished rhythmicity in plasma glucagon profiles. Scheduled-fed rats showed meal-induced glucagon peaks but also a daily rhythm in basal premeal glucagon concentrations. Plasma glucose concentrations of ad libitum– and scheduled-fed rats, however, were similar. In conclusion, feeding and the Biological Clock control 24-h plasma glucagon concentrations. In fed rats, glucagon is not responsible for the daily glucose rhythm. During fasting, however, glucagon may contribute to energy mobilization when the activity period starts. Diabetes 52:1709 –1715, 2003
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neuropeptide changes in the suprachiasmatic nucleus in primary hypertension indicate functional impairment of the Biological Clock
The Journal of Comparative Neurology, 2001Co-Authors: Valeri D Goncharuk, Joop Van Heerikhuize, Jiapei Dai, D F Swaab, Ruud M. BuijsAbstract:Abnormalities in autonomic activity resulting in disturbances of the diurnal rhythm of many physiologic processes were recently revealed in hypertensive patients. These findings suggest deteriorations in the functioning of the suprachiasmatic nucleus (SCN), which is known to be the Biological Clock of mammals. To test this hypothesis, we carried out an immunocytochemical study of the SCN of primary hypertension patients who had died due to myocardial infarction or brain hemorrhage, and compared them with those of individuals with a normal blood pressure who had never had any autonomic disturbances and died from myocardial infarction after chest trauma or from hypothermia. We found that the staining for the three main neuronal populations of the SCN; i.e., vasopressin, vasoactive intestinal polypeptide, and neurotensin, reduced by more than 50% in the hypertensives compared with controls. The present data indicate a serious dysregulation of the Biological Clock in hypertensive patients. Such a disturbance may cause a harmful hemodynamic imbalance with a negative effect on circulation, especially in the morning, when the inactivity-activity balance changes. The difficulty in adjusting from inactivity to activity might be involved in the morning clustering of cardiovascular events. J. Comp. Neurol. 431:320‐330, 2001. © 2001 Wiley-Liss, Inc. Indexing terms: blood pressure; hypothalamus; cardiovascular regulation; circadian rhythm; vasopressin
Andries Kalsbeek - One of the best experts on this subject based on the ideXlab platform.
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Vasopressin and the Output of the Hypothalamic Biological Clock
Journal of neuroendocrinology, 2010Co-Authors: Andries Kalsbeek, Ellen A. Fliers, M. A. Hofman, Dick F. Swaab, Ruud M. BuijsAbstract:The physiological effects of vasopressin as a peripheral hormone were first reported more than 100 years ago. However, it was not until the first immunocytochemical studies were carried out in the early 1970s, using vasopressin antibodies, and the discovery of an extensive distribution of vasopressin-containing fibres outside the hypothalamus, that a neurotransmitter role for vasopressin could be hypothesised. These studies revealed four additional vasopressin systems next to the classical magnocellular vasopressin system in the paraventricular and supraoptic nuclei: a sexually dimorphic system originating from the bed nucleus of the stria terminalis and the medial amygdala, an autonomic and endocrine system originating from the medial part of the paraventricular nucleus, and the circadian system originating from the hypothalamic suprachiasmatic nuclei (SCN). At about the same time as the discovery of the neurotransmitter function of vasopressin, it also became clear that the SCN contain the main component of the mammalian Biological Clock system (i.e. the endogenous pacemaker). This review will concentrate on the significance of the vasopressin neurones in the SCN for the functional output of the Biological Clock that is contained within it. The vasopressin-containing subpopulation is a characteristic feature of the SCN in many species, including humans. The activity of the vasopressin neurones in the SCN shows a pronounced daily variation in its activity that has also been demonstrated in human post-mortem brains. Animal experiments show an important role for SCN-derived vasopressin in the control of neuroendocrine day/night rhythms such as that of the hypothalamic-pituitary-adrenal and hypothalamic-pituitary-gonadal axes. The remarkable correlation between a diminished presence of vasopressin in the SCN and a deterioration of sleep-wake rhythms during ageing and depression make it likely that, also in humans, the vasopressin neurones contribute considerably to the rhythmic output of the SCN.
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The Biological Clock: The Bodyguard of Temporal Homeostasis
Chronobiology international, 2004Co-Authors: Stephanie Perreau-lenz, Ruud M. Buijs, Paul Pévet, Andries KalsbeekAbstract:In order for any organism to function properly, it is crucial that it be table to control the timing of its Biological functions. An internal Biological Clock, located, in mammals, in the suprachiasmatic nucleus of the hypothalamus (SCN), therefore carefully guards this temporal homeostasis by delivering its message of time throughout the body. In view of the large variety of body functions (behavioral, physiological, and endocrine) as well as the large variety in their preferred time of main activity along the light:dark cycle, it seems logical to envision different means of time distribution by the SCN. In the present review, we propose that even though it presents a unimodal circadian rhythm of general electrical and metabolic activity, the SCN seems to use several sorts of output connections that are active at different times along the light: dark cycle to control the rhythmic expression of different body functions. Although the SCN is suggested to use diffusion of synchronizing factors in the rhythmi...
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the daily rhythm in plasma glucagon concentrations in the rat is modulated by the Biological Clock and by feeding behavior
Diabetes, 2003Co-Authors: Marieke Ruiter, Andries Kalsbeek, Susanne E La Fleur, Caroline Van Heijningen, Jan Van Der Vliet, Ruud M. BuijsAbstract:Plasma glucose concentrations display a daily rhythm generated by the hypothalamic Biological Clock, located in the suprachiasmatic nucleus (SCN). How the SCN orchestrates this rhythm is unknown. Because glucagon stimulates hepatic glucose production, we hypothesized that if glucagon has a daily rhythm, then it may be responsible for the glucose rhythm. From hourly blood samples, we determined daily glucagon concentrations for intact and SCN-lesioned rats. Intact ad libitum–fed rats showed a clear daily glucagon rhythm, and fasting resulted in an even more pronounced rhythm. It is interesting that a decrease in glucagon concentrations, instead of the expected increase, occurred already shortly after food removal. Toward the start of the active period, a peak in glucagon levels occurred, with concentrations similar to those measured in ad libitum– fed rats. SCN lesions abolished rhythmicity in plasma glucagon profiles. Scheduled-fed rats showed meal-induced glucagon peaks but also a daily rhythm in basal premeal glucagon concentrations. Plasma glucose concentrations of ad libitum– and scheduled-fed rats, however, were similar. In conclusion, feeding and the Biological Clock control 24-h plasma glucagon concentrations. In fed rats, glucagon is not responsible for the daily glucose rhythm. During fasting, however, glucagon may contribute to energy mobilization when the activity period starts. Diabetes 52:1709 –1715, 2003
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the Biological Clock tunes the organs of the body timing by hormones and the autonomic nervous system
Journal of Endocrinology, 2003Co-Authors: R M Buijs, Valeri D Goncharuk, C G Van Eden, Andries KalsbeekAbstract:The Biological Clock, the suprachiasmatic nucleus (SCN), is essential for our daily well-being. It prepares us for the upcoming period of activity by an anticipatory rise in heart rate, glucose and cortisol. At the same time the ‘hormone of the darkness’, melatonin, decreases. Thus, the time-ofday message penetrates into all tissues, interestingly not only by means of hormones but also by a direct neuronal influence of the SCN on the organs of the body. The axis between the SCN and the paraventricular nucleus of the hypothalamus (PVN) is crucial for the organization/ synchronization of the neuroendocrine and autonomic nervous system with the time of day. This SCN– neuroendocrine PVN axis takes care of a timely hormonal secretion. At the same time, the SCN–autonomic PVN axis fine-tunes the organs by means of the autonomic nervous system for the reception of these hormones. Finally, the similar organization of the projections of the human SCN as compared with that in the rodent brain suggests that these basic principles of neuroendocrine autonomic interaction may also be true in the human. The physiological data collected in humans thus far seem to support this hypothesis, while pathological changes in the SCN of humans suffering from depression or hypertension indicate a role for the SCN in the etiology of these diseases.
Masaru Kojima - One of the best experts on this subject based on the ideXlab platform.
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Control of Biological Clock activity capsulated by lipid-mono-layer
2012 IEEE International Conference on Robotics and Automation, 2012Co-Authors: Masaru Kojima, Masahiro Nakajima, Michio Homma, Kingo Takiguchi, Takao Kondo, Toshio FukudaAbstract:In this paper, we try to establish new technique that the components of the Biological Clock are reconstituted into the liposome. In other words, we try to produce a nano size Clock, capsulated into the liposome, made by protein molecules. The circadian Clock is a basic cellular system found in almost all organisms. This Clock generates self-sustained oscillations under constant conditions with a ≈ 24-hour (circadian) period. In cyanobacteria, circadian Clock could be reconstituted in vitro only by mixing the three Clock proteins, KaiA, KaiB, KaiC, with adenosine triphosphate (ATP). So we reconstitute these proteins and adenosine triphosphate (ATP) into phospholipid-coated microdroplet and confirmed the Clock function. The Clocks in phospholipids-coated microdroplet indicate long period more than 24 hours. In this case, period length became 35 hour, self-sustaining oscillation was reaming with little dumping. To reveal why the time cycle became long period, we observed localization of Kai proteins in phospholipid-coated microdroplets by using fluorescents labeled Kai proteins under fluorescent (confocal) microscopy. From the observation of localization of Kai proteins, we found KaiB protein was distributed equivalently, on the other hand, KaiC protein was located near membrane of phospholipid-coated microdroplet. These results indicate that different localization between Kai proteins cause long period oscillation and we could control period length depend on calculation data from localization.
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Nano size Biological Clock capsulated by lipid layer: Reconstitution of Biological Clock into phospholipid-coated microdroplets
2009 9th IEEE Conference on Nanotechnology (IEEE-NANO), 2009Co-Authors: Masaru Kojima, Masae Ohno, Masahiro Nakajima, Michio Homma, Kingo Takiguchi, Takao Kondo, Toshio FukudaAbstract:We propose a nano size Clock, capsulated into micro size liposome, made by protein molecules. The circadian Clock is a basic cellular system found in almost all organisms. This Clock generates self-sustained oscillations under constant conditions with a ¿24-hour (circadian) period. In cyanobacteria, circadian Clock was reconstituted by only three proteins. We reconstitute these proteins and adenosine triphosphate (ATP; energy of Clock) into lipid layer and confirmed the Clock function. This system will reveal more detail about Biological Clock and bring application possibility.
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Reconstitution of Biological Clock into phospholipid-coated microdroplet
2009 International Symposium on Micro-NanoMechatronics and Human Science, 2009Co-Authors: Masaru Kojima, Masae Ohno, Masahiro Nakajima, Michio Homma, Kingo Takiguchi, Takao Kondo, Toshio FukudaAbstract:In this paper, we try to establish newly technique that the components of the Biological Clock are reconstituted into the liposome. In other words, we try to produce a nano size Clock, capsulated into the liposome, made by protein molecules. The Biological Clock is a basic cellular system found in almost all organisms. This Clock generates self-sustained oscillations under constant conditions with a ¿24-hour (circadian) period. Only three proteins in cyanobacteria reconstituted Biological Clock. We reconstitute these proteins and adenosine triphosphate (ATP) into phospholipid-coated microdroplet and confirmed the Clock function. This system will reveal more detailed about Biological Clock system and bring application possibility, such as drug delivery.
Ulrich Lüttge - One of the best experts on this subject based on the ideXlab platform.
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Circadian Rhythmicity: Is the “Biological Clock” Hardware or Software?
Progress in Botany, 2003Co-Authors: Ulrich LüttgeAbstract:Awareness of the influence of external rhythms such as seasons, Tides and the solar day on organisms, Plants and animals including humans, dates back to the early advent of human culture (Waterhouse 2001). One of the earliest demonstrations of an intrinsic or endogenous free-running daily rhythm in organisms is often acknowledged to be that of the nyctinastic day/night movements of the pinnulae of leaves of the higher plant Mimosa by (1729). Pioneers of higher-plant chronobiology are Wilhelm Pfeffer (1845–1920) and Erwin Bunning (1906–1990). Notwithstanding much work producing a wealth of evidence, even in the latter half of the twentieth century, It often occurred — as occasionally mentioned by Erwin Bunning—that the notion of a “Biological Clock” was associated with parascience. As recently as 1989 one could still read that biorhythmicity and the “Biological Clock” belonged to the field of parabiology together with fire-walking, The divining rod, And the like (Resch 1989). Conversely, International societies and journals of chronobiology were founded, And indeed occurrence of endogenous “daily” rhythmicity in organisms including green organisms such as the prokaryotic cyanobacteria, Eukaryotic unicellular and multicellular algae and higher plants is now a solid fact.
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period 2 cycles and 2 1 phase locking in a Biological Clock driven by temperature pulses
Journal of Theoretical Biology, 2002Co-Authors: Th M Hutt, F Beck, Uwe Rascher, Ulrich LüttgeAbstract:Abstract Crassulacean acid metabolism (CAM) serves as a botanical model system for the investigation of circadian rhythmicity. In a new set of experiments with the obligatory CAM plant Kalanchoe daigremontiana the response to periodic stimulations with temperature pulses has been studied. On the basis of an experimental phase–response curve of net CO 2 -gas exchange the effect of periodic stimulation has been simulated using a finite-difference equation. These simulations revealed the locations of two period-2 cycles in the CO 2 uptake of the CAM plant. In subsequent experiments based upon the simulated bifurcation diagram the position and amplitude of one of these cycles were confirmed, while experimental evidence for the second cycle could be found. Possible roles of such dynamics for the functioning of the Biological Clock are discussed.
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stochastic noise interferes coherently with a model Biological Clock and produces specific dynamic behaviour
Proceedings of The Royal Society B: Biological Sciences, 2001Co-Authors: F Beck, Ulrich Lüttge, Bernd Blasius, R Neff, Uwe RascherAbstract:The influence of noise is unavoidable in all living systems. Its impact on a model of a Biological Clock, normally running in regular oscillating modes, is examined. It is shown that in a specific system in which endogenous rhythmicity is produced by a beat oscillator acting on a feedback coupled metabolic pool system, noise can act coherently to produce unexpected dynamic behaviour, running from regular over pseudo-regular to irregular time-structures. If the Biological system consists of a set of identical weakly coupled cells, stochasticity may lead to phase decoupling producing irregular spatio-temporal patterns. Synchronization via phase resetting can be achieved by external short-time temperature pulses. Explicit results are obtained for the well-studied circadian photosynthesis oscillations in plants performing crassulacean acid metabolism. Because of the generic structure of the underlying nonlinear dynamics they can, however, be regarded as a general property of the influence of noise on nonlinear excitable systems with fixed points occuring close to limit cycles.
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spatio temporal variation of photosynthetic activity during the endogenous circadian cam rhythm of kalanchoe daigremontiana the Biological Clock as an assembly of coupled nonlinear oscillators
Science Access, 2001Co-Authors: Uwe Rascher, Mth Hutt, C B Osmond, Katharina Siebke, Ulrich LüttgeAbstract:The complex dynamical properties of Biological timing in organisms could never be fully accounted for, not even by increasingly precise characterization of oscillating units and their components. The circadian rhythm of CO2 exchange of the crassulacean acid metabolism plant Kalanchoe daigremontiana is regarded as a generic model system for exploration of endogenous rhythmicity in a well understood metabolic pathway. While the CAM-rhythm so far was thought to be solely time-dependent, we show here for the first time that the circadian rhythm of a metabolic cycle in a higher plant is expressed as independently initiated variations in photosynthetic efficiency (f PSII) over a single leaf. Non-invasive, highly sensitive chlorophyll fluorescence imaging under well controlled external conditions reveals dynamic clusters, moving wave fronts and clearly dephased regions of f PSII. This is the first demonstration that this Biological Clock is a spatio-temporal product of many weakly coupled oscillators. These oscillators are defined by the metabolic constraints of CAM but operate independently in space and time as a consequence of the dynamics of metabolic pools and limitations of CO2 diffusion between tightly packed cells. Several, especially long term aspects of this Biological Clock are strongly related to the self-organization of the interacting oscillators in space. We propose that synchronization of these individual oscillators is essential for the functioning of the Biological Clock.