Twilight and day length affects the seasonality of entrainment and endogenous circadian rhythms in a fish, Couesius plumbeus

1981 ◽  
Vol 59 (7) ◽  
pp. 1326-1334 ◽  
Author(s):  
Martin Kavaliers ◽  
Donald M. Ross
Keyword(s):  
Circadian Rhythms ◽  
Seasonal Changes ◽  
Phase Relationship ◽  
Day Length ◽  
Constant Darkness ◽  
Diurnal Activity ◽  
Circadian Period ◽  
Dark Cycle ◽  
Environmental Light ◽  
Couesius Plumbeus

Twilight and day-length portions of the light-dark cycle determine the seasonal course of (i) the phase relationship (ψ) between activity and the daily environmental light–dark cycle, (ii) the duration of activity (α), and (iii) the circadian period (τ) under constant darkness of the lake chub (Couesius plumbeus). With fish held under seasonally appropriate light–dark cycles with twilight (LD + t), the onset of diurnal activity occurred during dawn and its timing (ψonset) followed a bimodal annual pattern that was correlated with seasonal changes in the duration and physical characteristics of twilight. The end of activity occurred during dusk (ψoffset) and followed a unimodal annual pattern that was determined by day length. α followed a sigmoidal annual pattern under LD + t. The circadian period underwent significant seasonal changes with maximum and minimum τ values occurring during summer and winter, respectively. Fish that were entrained to rectangular light–dark cycles that excluded twilights (LD) failed to show any seasonal changes in ψ and τ and the sigmoidal relation between α and day length was absent.

Seasonal changes in the circadian period of the lake chub, Couesius plumbeus

1978 ◽  
Vol 56 (12) ◽  
pp. 2591-2596 ◽  
Author(s):  
Martin Kavaliers
Keyword(s):  
Seasonal Changes ◽  
Constant Darkness ◽  
Circadian Period ◽  
Minimum Period ◽  
Annual Variations ◽  
Circadian Organization ◽  
Annual Changes ◽  
The Times ◽  
Couesius Plumbeus

Systematic seasonal and annual changes are present in the length of the circadian period, τ, of the lake chub, Couesius plumbeus. Maximum and minimum period values of 28.1 and 24.8 h were recorded under constant darkness from fish obtained at the times of the winter and summer solstices, respectively. There was an asymmetric annual pattern in the τ values obtained from the increasing and decreasing photoperiods of spring and fall. Annual variations in τ were relatively independent of temperature. They were interpreted as being aftereffects of natural photoperiodic entrainment. Relations of annual changes in the length of the period to models of circadian organization and entrainment are examined.

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 Roles of Neuropeptides, VIP and AVP, in the Mammalian Central Circadian Clock

2021 ◽  
Vol 15 ◽  
Author(s):  
Daisuke Ono ◽  
Ken-ichi Honma ◽  
Sato Honma
Keyword(s):  
Transcription Factors ◽  
Circadian Rhythms ◽  
Circadian Clock ◽  
Cellular Networks ◽  
Clock Genes ◽  
Circadian System ◽  
Developmental Changes ◽  
Circadian Period ◽  
Functional Roles ◽  
Environmental Light

In mammals, the central circadian clock is located in the suprachiasmatic nucleus (SCN) of the hypothalamus. Individual SCN cells exhibit intrinsic oscillations, and their circadian period and robustness are different cell by cell in the absence of cellular coupling, indicating that cellular coupling is important for coherent circadian rhythms in the SCN. Several neuropeptides such as arginine vasopressin (AVP) and vasoactive intestinal polypeptide (VIP) are expressed in the SCN, where these neuropeptides function as synchronizers and are important for entrainment to environmental light and for determining the circadian period. These neuropeptides are also related to developmental changes of the circadian system of the SCN. Transcription factors are required for the formation of neuropeptide-related neuronal networks. Although VIP is critical for synchrony of circadian rhythms in the neonatal SCN, it is not required for synchrony in the embryonic SCN. During postnatal development, the clock genes cryptochrome (Cry)1 and Cry2 are involved in the maturation of cellular networks, and AVP is involved in SCN networks. This mini-review focuses on the functional roles of neuropeptides in the SCN based on recent findings in the literature.

scholarly journals The fish watch: Zebrafish: a clock in every cell

2005 ◽  
Vol 27 (6) ◽  
pp. 23-26
Author(s):  
Amanda-Jayne F. Carr ◽  
David Whitmore
Keyword(s):  
Circadian Rhythms ◽  
Danio Rerio ◽  
Biological Process ◽  
Genetic Model ◽  
Model System ◽  
Biological Processes ◽  
Powerful Method ◽  
Dark Cycle ◽  
Environmental Light ◽  
The One

The environmental light–dark cycle is one of the most reliable rhythmic signals, and many organisms have evolved a circadian (circa diem, ‘about a day’) system to co-ordinate biological processes with this predictable environmental change. These rhythms are endogenous and persist even in constant conditions, the light–dark cycle serving to synchronize these rhythms precisely to 24 hours. Genetic approaches have proved invaluable in increasing our understanding of the circadian clock. The ability to isolate a mutant with a defect in a rhythmic process is a very powerful method, which depends on no prior assumptions about the biological process under investigation. Consequently, Drosophila and the mouse have become the most powerful genetic models to study circadian rhythms in animals. The one alternative vertebrate genetic model system to the mouse is the zebrafish (Danio rerio).

scholarly journals Neuron-specific knockouts indicate the importance of network communication to Drosophila rhythmicity

2019 ◽  
Author(s):  
M Schlichting ◽  
MM Diaz ◽  
J Xin ◽  
M Rosbash
Keyword(s):  
Gene Expression ◽  
Circadian Rhythms ◽  
Intercellular Communication ◽  
Clock Gene ◽  
Feedback Loops ◽  
Neuronal Firing ◽  
Network Communication ◽  
Constant Darkness ◽  
Circadian Period ◽  
Clock Gene Expression

AbstractAnimal circadian rhythms persist in constant darkness and are driven by intracellular transcription-translation feedback loops. Although these cellular oscillators communicate, isolated mammalian cellular clocks continue to tick away in darkness without intercellular communication. To investigate these issues in Drosophila, we assayed behavior as well as molecular rhythms within individual brain clock neurons while blocking communication within the ca. 150 neuron clock network. We also generated CRISPR-mediated neuron-specific circadian clock knockouts. The results point to two key clock neuron groups: loss of the clock within both regions but neither one alone has a strong behavioral phenotype in darkness; communication between these regions also contributes to circadian period determination. Under these dark conditions, the clock within one region persists without network communication. The clock within the famous PDF-expressing s-LNv neurons however was strongly dependent on network communication, likely because clock gene expression within these vulnerable sLNvs depends on neuronal firing or light.

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.

Seasonal changes in the short-term activity and ultradian rhythms of a cyprinid fish, the lake chub, Couesius plumbeus

1981 ◽  
Vol 59 (3) ◽  
pp. 486-492 ◽  
Author(s):  
Martin Kavaliers
Keyword(s):  
Seasonal Changes ◽  
Temporal Pattern ◽  
Circadian System ◽  
Cyprinid Fish ◽  
Constant Darkness ◽  
Ultradian Rhythms ◽  
Short Term ◽  
Free Running ◽  
Annual Changes ◽  
Couesius Plumbeus

The temporal pattern of the locomotor activity of a cyprinid fish, the lake chub, Couesius plumbeus, was examined under seasonally appropriate light–dark cycles that included twilights and under constant darkness. Photoperiodically entrained and free-running circadian activity from constant darkness was composed of nonrandomly distributed short-term activity components (0.5–3.5 h) with significant ultradian frequencies. In both cases there was an annual rhythm in the length of the ultradian periods, ranging from 0.7 h in winter to 2.5 h in summer. This pattern was accompanied by annual changes in the frequency distribution of short-term activity components. Ultradian periods were correlated with both daylength in the entraining light–dark cycles and the seasonal changes in the circadian period of fish free-running under constant darkness. These results suggest that the expression of ultradian rhythms and short-term locomotor bouts is controlled by a multioscillator circadian system.

scholarly journals Melatonin Adjusts the Phase of Mouse Circadian Clocks in the Cornea Both Ex Vivo and In Vivo

2021 ◽  
pp. 074873042110323
Author(s):  
Alex V. Huynh ◽  
Ethan D. Buhr
Keyword(s):  
Mammalian Cells ◽  
Ex Vivo ◽  
Circadian Clocks ◽  
Constant Darkness ◽  
Environmental Cues ◽  
Dark Cycle ◽  
Environmental Light ◽  
Advanced Phase ◽  
Different Tissues

The presence of an endogenous circadian clock within most mammalian cells is associated with the amazing observation that within a given tissue, these clocks are largely in synchrony with each other. Different tissues use a variety of systemic or environmental cues to precisely coordinate the phase of these clocks. The cornea is a unique tissue in that it is largely isolated from the direct blood supply that most tissues experience, it is transparent to visible light, and it is exposed directly to environmental light and temperature. Melatonin is a hormone that has been implicated in regulation of the cornea’s circadian clocks. Here, we analyze the ability of rhythmic melatonin to entrain corneas ex vivo, and analyze the phase of corneal circadian clocks in vivo both in light: dark cycles and in constant darkness. We find that the presence of a retina from a melatonin-proficient mouse strain, C3Sn, can photoentrain the circadian clocks of a co-cultured mouse cornea, but a retina from a melatonin-deficient strain, C57Bl/6, cannot. Furthermore, pharmacologic blockade of melatonin or use of a retina with advanced retinal degeneration, Pde6brd1, blocks the photoentraining effect. Corneal circadian clocks in vivo adopt an advanced phase in C3Sn mice compared with C57Bl/6, but the circadian clocks in the liver are unaffected. This observation is not attributable to a shorter endogenous period of the cornea or behavior between the strains. Some transcripts of circadian genes in the corneas of C3Sn mice also show an advanced phase of expression in a light: dark cycle, while the transcript of Per2 exhibits a light-dependent transient induction at the onset of darkness. We conclude that melatonin acts as a phase modifying factor in a rhythmic manner for the circadian clocks of the cornea.

Suppression of men's responses to seasonal changes in day length by modern artificial lighting

1995 ◽  
Vol 269 (1) ◽  
pp. R173-R178 ◽  
Author(s):  
T. A. Wehr ◽  
H. A. Giesen ◽  
D. E. Moul ◽  
E. H. Turner ◽  
P. J. Schwartz
Keyword(s):  
Urban Environment ◽  
Rectal Temperature ◽  
Seasonal Changes ◽  
Day Length ◽  
Constant Darkness ◽  
Artificial Light ◽  
Active Secretion ◽  
Artificial Lighting ◽  
Natural Photoperiod ◽  
Low Levels

We recently reported that humans have conserved mechanisms, like those that exist in other animals, which detect changes in day length and make corresponding adjustments in the duration of nocturnal periods of secretion of melatonin and of other functions. We detected these responses in individuals who were exposed to artificial "days" of different durations. The purpose of the present study was to determine whether men who are exposed to natural and artificial light in an urban environment at 39 degrees N are still able to detect and respond to seasonal changes in duration of the natural photoperiod. We measured profiles of circadian rhythms during 24-h periods of constant darkness (< 1 lx) and found no summer-winter differences in durations of nocturnal periods of active secretion of melatonin, rising levels of cortisol, high levels of thyrotropin, and low levels of rectal temperature. The results of this and our previous study suggest that modern men's use of artificial light suppresses responses to seasonal changes in the natural photoperiod that might otherwise occur at this latitude.

Circadian activity of the white sucker, Catostomus commersoni: comparison of individual and shoaling fish

1980 ◽  
Vol 58 (8) ◽  
pp. 1399-1403 ◽  
Author(s):  
Martin Kavaliers
Keyword(s):  
Locomotor Activity ◽  
Circadian Rhythms ◽  
Social Organization ◽  
Constant Darkness ◽  
White Sucker ◽  
Circadian Period ◽  
Circadian Activity ◽  
Catostomus Commersoni ◽  
Free Running ◽  
Precise Version

Individual and shoaling white suckers, Catostomus commersoni, displayed free running circadian rhythms of locomotor activity under conditions of constant darkness and temperature. The circadian activity of shoals was different from that of single fish. The activity of single fish was rhythmic initially with a period of less than 24 h, but became arrhythmic after 15–30 days. Shoals of white suckers had a less variable circadian period that was greater than 24 h, and showed no evidence of arrhythmicity. The circadian activity of shoals is determined by its behavioural and social organization; it is not simply a more precise version of the activity of single fish.

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