scholarly journals Circadian molecular clocks tick along ontogenesis

2008 ◽  
pp. S139-S148
Author(s):  
A Sumová ◽  
Z Bendová ◽  
M Sládek ◽  
R El-Hennamy ◽  
K Matějů ◽  
...  
Keyword(s):  
Current Model ◽  
Complex Structure ◽  
Postnatal Period ◽  
Circadian System ◽  
Molecular Clocks ◽  
Suprachiasmatic Nuclei ◽  
Intercellular Coupling ◽  
Peripheral Clocks ◽  
Complete Set ◽  
Formal Properties

The circadian system controls the timing of behavioral and physiological functions in most organisms studied. The review addresses the question of when and how the molecular clockwork underlying circadian oscillations within the central circadian clock in the suprachiasmatic nuclei of the hypothalamus (SCN) and the peripheral circadian clocks develops during ontogenesis. The current model of the molecular clockwork is summarized. The central SCN clock is viewed as a complex structure composed of a web of mutually synchronized individual oscillators. The importance of development of both the intracellular molecular clockwork as well as intercellular coupling for development of the formal properties of the circadian SCN clock is also highlighted. Recently, data has accumulated to demonstrate that synchronized molecular oscillations in the central and peripheral clocks develop gradually during ontogenesis and development extends into postnatal period. Synchronized molecular oscillations develop earlier in the SCN than in the peripheral clocks. A hypothesis is suggested that the immature clocks might be first driven by external entraining cues, and therefore, serve as "slave" oscillators. During ontogenesis, the clocks may gradually develop a complete set of molecular interlocked oscillations, i.e., the molecular clockwork, and become self-sustained clocks.

Maternal-fetal communication of circadian phase in a precocious rodent, the spiny mouse

1987 ◽  
Vol 253 (4) ◽  
pp. E401-E409
Author(s):  
D. R. Weaver ◽  
S. M. Reppert
Keyword(s):  
Circadian Rhythms ◽  
Postnatal Period ◽  
Spiny Mouse ◽  
Constant Darkness ◽  
Suprachiasmatic Nuclei ◽  
Maternal Influences ◽  
Circadian Phase ◽  
Environmental Light ◽  
Running Activity ◽  
Free Running

The development of circadian rhythms was examined in a precocious rodent species, the spiny mouse. Spiny mouse pups born and reared in constant darkness expressed robust circadian rhythms in locomotor activity as early as day 5 of life. Free-running activity rhythms of pups born and reared in constant darkness were coordinated with the dam on the day of birth. Postnatal maternal influences on pup rhythmicity are minimal in this species, as pups fostered on the day of birth to dams whose circadian phases were opposite to the pups' original dams were coordinated with their original dams on the day of birth. Studies using 2-deoxy-D-[1-14C]-glucose autoradiography showed that there were synchronous (coordinated) rhythms in metabolic activity in the maternal and fetal suprachiasmatic nuclei, directly demonstrating prenatal coordination of maternal and fetal rhythmicity. Maternal-fetal coordination of circadian phase was not the result of direct entrainment of the fetuses to the environmental light-dark cycle. These results demonstrate that there is prenatal communication of circadian phase in this precocious species, without demonstrable postnatal maternal influences on pup circadian rhythmicity. Spiny mice therefore represent an important animal model in which circadian rhythms in the postnatal period can be used to precisely assess prenatal influences on circadian phase.

scholarly journals Two Novel Phycoerythrin-Associated Linker Proteins in the Marine Cyanobacterium Synechococcus sp. Strain WH8102

2005 ◽  
Vol 187 (5) ◽  
pp. 1685-1694 ◽  
Author(s):  
Christophe Six ◽  
Jean-Claude Thomas ◽  
Laurent Thion ◽  
Yves Lemoine ◽  
Frank Zal ◽  
...  
Keyword(s):  
Biochemical Analysis ◽  
Complex Structure ◽  
High Light ◽  
Dramatic Reduction ◽  
Marine Cyanobacterium ◽  
Global View ◽  
Genomic Analyses ◽  
Complete Set ◽  
Synechococcus Sp ◽  
Classical Size

ABSTRACT The recent availability of the whole genome of Synechococcus sp. strain WH8102 allows us to have a global view of the complex structure of the phycobilisomes of this marine picocyanobacterium. Genomic analyses revealed several new characteristics of these phycobilisomes, consisting of an allophycocyanin core and rods made of one type of phycocyanin and two types of phycoerythrins (I and II). Although the allophycocyanin appears to be similar to that found commonly in freshwater cyanobacteria, the phycocyanin is simpler since it possesses only one complete set of α and β subunits and two rod-core linkers (CpcG1 and CpcG2). It is therefore probably made of a single hexameric disk per rod. In contrast, we have found two novel putative phycoerythrin-associated linker polypeptides that appear to be specific for marine Synechococcus spp. The first one (SYNW2000) is unusually long (548 residues) and apparently results from the fusion of a paralog of MpeC, a phycoerythrin II linker, and of CpeD, a phycoerythrin-I linker. The second one (SYNW1989) has a more classical size (300 residues) and is also an MpeC paralog. A biochemical analysis revealed that, like MpeC, these two novel linkers were both chromophorylated with phycourobilin. Our data suggest that they are both associated (partly or totally) with phycoerythrin II, and we propose to name SYNW2000 and SYNW1989 MpeD and MpeE, respectively. We further show that acclimation of phycobilisomes to high light leads to a dramatic reduction of MpeC, whereas the two novel linkers are not significantly affected. Models for the organization of the rods are proposed.

The neural circadian system of mammals

2011 ◽  
Vol 49 ◽  
pp. 1-17 ◽  
Author(s):  
Hugh D. Piggins ◽  
Clare Guilding
Keyword(s):  
Circadian Rhythms ◽  
Circadian System ◽  
Daily Activities ◽  
Suprachiasmatic Nuclei ◽  
Dark Cycle ◽  
Environmental Light ◽  
Endogenous Clock ◽  
Central Clock

Humans and other mammals exhibit a remarkable array of cyclical changes in physiology and behaviour. These are often synchronized to the changing environmental light–dark cycle and persist in constant conditions. Such circadian rhythms are controlled by an endogenous clock, located in the suprachiasmatic nuclei of the hypothalamus. This structure and its cells have unique properties, and some of these are reviewed to highlight how this central clock controls and sculpts our daily activities.

scholarly journals Features of application of fundamental knowledge in innovative space: ontological aspect

2020 ◽  
Vol 157 ◽  
pp. 04012
Author(s):  
Julia Kharchenko ◽  
Sergej Kharchenko ◽  
Olena Sidorkina ◽  
Alla Fabrika ◽  
Oleg Rusul
Keyword(s):  
Current Model ◽  
Complex Structure ◽  
Time Frame ◽  
Natural Phenomena ◽  
Fundamental Knowledge ◽  
Artificial Environment ◽  
Ontological Approach ◽  
New Knowledge ◽  
High Dynamics ◽  
Ontological Aspect

The analysis of the innovative space with a complex structure and configuration has been conducted by showing that its space-time frame is uncertain due to the high dynamics. The results obtained from the analysis of virtuum as a kind of multidimensional reality, forming a new image of society and, at the same time, generating and combining new knowledge. Knowledge and innovation are shown as the fundamental dominant of the current model of society and as the result this model combines the characteristics of informational, cybercultural, technogenic, virtual, and innovative society. On this basis, the main purpose of the research was implementation of the correlation of innovative creations and new epistemes, which were the foundation of the innovative space. The ontological approach that became the theoretical basis of this research showed that the innovative space is understood as one of the multidimensional sphere of social existence as such, including all actors of innovation. The results of the research confirmed that fundamental knowledge is updating the epistemological resource, at the same time, the mechanisms and methodology of research are constantly changing, technical and technological tools are being modernized and all of these factors influence on innovative space. Besides, innovative space as an artificial environment is correcting social and natural phenomena.

scholarly journals Nutrition and the circadian system

2016 ◽  
Vol 116 (3) ◽  
pp. 434-442 ◽  
Author(s):  
Gregory D. M. Potter ◽  
Janet E. Cade ◽  
Peter J. Grant ◽  
Laura J. Hardie
Keyword(s):  
Environmental Changes ◽  
Time Of Day ◽  
Circadian System ◽  
Suprachiasmatic Nuclei ◽  
Peripheral Tissues ◽  
Physiological Processes ◽  
Nutritional Science ◽  
High Fat Diets ◽  
Nutritional Compounds ◽  
Fat Diets

AbstractThe human circadian system anticipates and adapts to daily environmental changes to optimise behaviour according to time of day and temporally partitions incompatible physiological processes. At the helm of this system is a master clock in the suprachiasmatic nuclei (SCN) of the anterior hypothalamus. The SCN are primarily synchronised to the 24-h day by the light/dark cycle; however, feeding/fasting cycles are the primary time cues for clocks in peripheral tissues. Aligning feeding/fasting cycles with clock-regulated metabolic changes optimises metabolism, and studies of other animals suggest that feeding at inappropriate times disrupts circadian system organisation, and thereby contributes to adverse metabolic consequences and chronic disease development. ‘High-fat diets’ (HFD) produce particularly deleterious effects on circadian system organisation in rodents by blunting feeding/fasting cycles. Time-of-day-restricted feeding, where food availability is restricted to a period of several hours, offsets many adverse consequences of HFD in these animals; however, further evidence is required to assess whether the same is true in humans. Several nutritional compounds have robust effects on the circadian system. Caffeine, for example, can speed synchronisation to new time zones after jetlag. An appreciation of the circadian system has many implications for nutritional science and may ultimately help reduce the burden of chronic diseases.

scholarly journals Circadian Rhythm and Sleep Disruption: Causes, Metabolic Consequences, and Countermeasures

2016 ◽  
Vol 37 (6) ◽  
pp. 584-608 ◽  
Author(s):  
Gregory D. M. Potter ◽  
Debra J. Skene ◽  
Josephine Arendt ◽  
Janet E. Cade ◽  
Peter J. Grant ◽  
...  
Keyword(s):  
Circadian Rhythm ◽  
Circadian System ◽  
Sleep Disruption ◽  
Molecular Clocks ◽  
Global Trends ◽  
Artificial Lighting ◽  
Dietary Choices ◽  
Increased Risk ◽  
Daily Cycles ◽  
Pharmaceutical Interventions

Abstract Circadian (∼24-hour) timing systems pervade all kingdoms of life and temporally optimize behavior and physiology in humans. Relatively recent changes to our environments, such as the introduction of artificial lighting, can disorganize the circadian system, from the level of the molecular clocks that regulate the timing of cellular activities to the level of synchronization between our daily cycles of behavior and the solar day. Sleep/wake cycles are intertwined with the circadian system, and global trends indicate that these, too, are increasingly subject to disruption. A large proportion of the world's population is at increased risk of environmentally driven circadian rhythm and sleep disruption, and a minority of individuals are also genetically predisposed to circadian misalignment and sleep disorders. The consequences of disruption to the circadian system and sleep are profound and include myriad metabolic ramifications, some of which may be compounded by adverse effects on dietary choices. If not addressed, the deleterious effects of such disruption will continue to cause widespread health problems; therefore, implementation of the numerous behavioral and pharmaceutical interventions that can help restore circadian system alignment and enhance sleep will be important.

scholarly journals Interplay between the endocrine and circadian systems in fishes

2017 ◽  
Vol 232 (3) ◽  
pp. R141-R159 ◽  
Author(s):  
Esther Isorna ◽  
Nuria de Pedro ◽  
Ana I Valenciano ◽  
Ángel L Alonso-Gómez ◽  
María J Delgado
Keyword(s):  
Current Model ◽  
Circadian System ◽  
Energy Status ◽  
Clock Gene Expression ◽  
Status Signalling ◽  
Daily Cycles ◽  
Light Darkness ◽  
Acute Changes ◽  
First Time

The circadian system is responsible for the temporal organisation of physiological functions which, in part, involves daily cycles of hormonal activity. In this review, we analyse the interplay between the circadian and endocrine systems in fishes. We first describe the current model of fish circadian system organisation and the basis of the molecular clockwork that enables different tissues to act as internal pacemakers. This system consists of a net of central and peripherally located oscillators and can be synchronised by the light–darkness and feeding–fasting cycles. We then focus on two central neuroendocrine transducers (melatonin and orexin) and three peripheral hormones (leptin, ghrelin and cortisol), which are involved in the synchronisation of the circadian system in mammals and/or energy status signalling. We review the role of each of these as overt rhythms (i.e. outputs of the circadian system) and, for the first time, as key internal temporal messengers that act as inputs for other endogenous oscillators. Based on acute changes in clock gene expression, we describe the currently accepted model of endogenous oscillator entrainment by the light–darkness cycle and propose a new model for non-photic (endocrine) entrainment, highlighting the importance of the bidirectional cross-talking between the endocrine and circadian systems in fishes. The flexibility of the fish circadian system combined with the absence of a master clock makes these vertebrates a very attractive model for studying communication among oscillators to drive functionally coordinated outputs.

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