Monophasic and diphasic patterns of the circadian caecotrophy rhythm of rabbits

1982 ◽  
Vol 16 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Burghart Jilge
Keyword(s):  
Dark Period ◽  
Continuous Light ◽  
Light Period ◽  
Period Length ◽  
Rodent Species ◽  
Average Period ◽  
Dark Cycle

The circadian caecotrophy rhythm was synchronized with the light-dark cycle of 12 : 12 h. During this the rabbits practised caecotrophy regularly during the light period. While most rabbits manifested 1 caecotrophy per 24 h (monophasic caecotrophy), some had an additional caecotrophy during the dark period (diphasic caecotrophy). During continuous light the circadian caecotrophy rhythm ran free monophasically, even in those rabbits which were diphasic under the preceding 12 : 12 regime. The average period length amounted to 24·7 ± 0·3 h. Following restoration of the 12 : 12 routine animals reestablished their original caecotrophy pattern. In a further test the caecotrophy pattern remained constant during a constant 12 : 12 regimen, but changed in 7 of 16 animals when the photoperiod was reduced first to 60 min and then to 2 × 60 min light every 24 h. The reduction of the lit time resulted in an increased occurrence of diphasic animals. Details of synchronization of the caecotrophy rhythm with the different light-dark schedules are given. These results accord with data obtained in nocturnal rodent species.

Stimulation of Melatonin Receptors Decreases Calcium Levels in Xenopus Tectal Cells by Activating GABAC Receptors

2005 ◽  
Vol 94 (2) ◽  
pp. 968-978 ◽  
Author(s):  
Claudia Prada ◽  
Susan B. Udin ◽  
Allan F. Wiechmann ◽  
Irina V. Zhdanova
Keyword(s):  
Receptor Antagonist ◽  
Dark Period ◽  
Light Period ◽  
Melatonin Receptors ◽  
Receptor Activity ◽  
Calcium Dynamics ◽  
Rt Pcr ◽  
Dark Cycle ◽  
Bath Application ◽  
Stimulation Of

To investigate the physiological effects of melatonin receptors in the Xenopus tectum, we have used the fluorescent indicator Fluo-4 AM to monitor calcium dynamics of cells in tectal slices. Bath application of KCl elicited fluorescence increases that were reduced by melatonin. This effect was stronger at the end of the light period than at the end of the dark period. Melatonin increased γ-aminobutyric acid-C (GABAC)–receptor activity, as demonstrated by the ability of the GABAC-receptor antagonists, picrotoxin and TPMPA, to abolish the effects of melatonin. In contrast, neither the GABAA-receptor antagonist bicuculline nor the GABAB-receptor antagonist CGP 35348 diminished the effects of melatonin. RT-PCR analyses revealed expression of the 3 known melatonin receptors, MT1 (Mel1a), MT2 (Mel1b), and Mel1c. Because the effect of melatonin on tectal calcium increases was antagonized by an MT2-selective antagonist, 4-P-PDOT, we performed Western blot analyses with an antibody to the MT2 receptor; the data indicate that the MT2 receptor is expressed primarily as a dimeric complex and is glycosylated. The receptor is present in higher amounts at the end of the light period than at the end of the dark period, in a pattern complementary to the changes in melatonin levels, which are higher during the night than during the day. These results imply that melatonin, acting by MT2 receptors, modulates GABAC receptor activity in the optic tectum and that this effect is influenced by the light–dark cycle.

Diurnal Differences in the Innermost Surface of the S2 Layer in Differentiating Tracheids of Cryptomeria japonica Corresponding to a Light-Dark Cycle

Holzforschung ◽  
2003 ◽  
Vol 57 (6) ◽  
pp. 567-573 ◽  
Author(s):  
Y. Hosoo ◽  
M. Yoshida ◽  
T. Imai ◽  
T. Okuyama
Keyword(s):  
Cryptomeria Japonica ◽  
Dark Period ◽  
Amorphous Material ◽  
Light Period ◽  
Cellulose Microfibrils ◽  
Dark Phase ◽  
Diurnal Changes ◽  
Dark Cycle ◽  
Tangential Strain ◽  
S2 Layer

Summary This paper describes the effect of light on the diurnal change in the innermost surface of developing secondary walls. Cryptomeria japonica D. Don saplings were grown in two growth chambers, in which temperature and relative humidity were kept constant and the light-dark phase of the photoperiod varied. One chamber reproduced the natural light-dark phase, while the other reversed it. Samples of differentiating xylem were collected during the dark period when the tangential strain, used as an index of volumetric changes in differentiating cells, was high, and during the light period when the tangential strain was low. The innermost surface of developing secondary walls in differentiating tracheids was observed by field emission scanning electron microscopy. In the specimens collected during the dark period, amorphous material was observed and the cell wall surface was immunogold-labeled with an anti-glucomannan antiserum. In the specimens collected during the light period, cellulose microfibrils were clearly evident, and amorphous material and immunogold labeling were rarely observed. These results demonstrate that the diurnal changes in the innermost surface of developing secondary walls correspond to the light-dark cycle over 24 h.

scholarly journals Shifting eating to the circadian rest phase misaligns the peripheral clocks with the master SCN clock and leads to a metabolic syndrome

2015 ◽  
Vol 112 (48) ◽  
pp. E6691-E6698 ◽  
Author(s):  
Atish Mukherji ◽  
Ahmad Kobiita ◽  
Manohar Damara ◽  
Nisha Misra ◽  
Hamid Meziane ◽  
...  
Keyword(s):  
Metabolic Syndrome ◽  
Molecular Level ◽  
Dark Period ◽  
Active Phase ◽  
Light Period ◽  
Dark Cycle ◽  
Peripheral Clocks ◽  
Molecular Signals ◽  
Glucagon Receptors

The light-entrained master central circadian clock (CC) located in the suprachiasmatic nucleus (SCN) not only controls the diurnal alternance of the active phase (the light period of the human light-dark cycle, but the mouse dark period) and the rest phase (the human dark period, but the mouse light period), but also synchronizes the ubiquitous peripheral CCs (PCCs) with these phases to maintain homeostasis. We recently elucidated in mice the molecular signals through which metabolic alterations induced on an unusual feeding schedule, taking place during the rest phase [i.e., restricted feeding (RF)], creates a 12-h PCC shift. Importantly, a previous study showed that the SCN CC is unaltered during RF, which creates a misalignment between the RF-shifted PCCs and the SCN CC-controlled phases of activity and rest. However, the molecular basis of SCN CC insensitivity to RF and its possible pathological consequences are mostly unknown. Here we deciphered, at the molecular level, how RF creates this misalignment. We demonstrate that the PPARα and glucagon receptors, the two instrumental transducers in the RF-induced shift of PCCs, are not expressed in the SCN, thereby preventing on RF a shift of the master SCN CC and creating the misalignment. Most importantly, this RF-induced misalignment leads to a misexpression (with respect to their normal physiological phase of expression) of numerous CC-controlled homeostatic genes, which in the long term generates in RF mice a number of metabolic pathologies including diabetes, obesity, and metabolic syndrome, which have been reported in humans engaged in shift work schedules.

scholarly journals Resetting Process of Peripheral Circadian Gene Expression after the Combined Reversal of Feeding Schedule and Light/Dark Cycle Via a 24-h Light Period Transition in Rats

2010 ◽  
pp. 581-590
Author(s):  
T Wu ◽  
Y Ni ◽  
F Zhuge ◽  
Z Fu
Keyword(s):  
Time Course ◽  
Clock Genes ◽  
Dark Period ◽  
Light Period ◽  
Feeding Schedule ◽  
Circadian Gene ◽  
Dark Cycle ◽  
Peripheral Clocks ◽  
Effect Of Light

To investigate the effect of light cue on the resetting of the peripheral clocks, we examined the resetting processes of clock genes (Per1, Per2, Bmal1, Cry1, Dec1, and Rev-erbα) in the liver and heart of rats after the feeding and light-dark (LD) reversal via a 24-h light period transition. The liver clock was reset quickly within 3 days, while the heart clock needed a longer time course of 5-7 days to be completely re-entrained. Moreover, the reentrainment of Per1 and Per2 in the liver clock was more rapid than that of the other four clock genes, suggesting the important role of these two clock genes in initiating the circadian resetting of the hepatic clock. However, the resetting rates of these two clock genes were as similar as the others in the heart clock. Therefore, the resetting mechanisms underlining these two peripheral clocks may be totally distinct. Furthermore, the reentrainment of the liver and heart clocks were relatively lengthened after the feeding and LD reversal via a light period transition compared to a dark period transition, suggesting a simultaneous shift of feeding schedule and the LD cycle may facilitate the circadian resetting in rats.

Diel periodicity in spermatophore formation in the house cricket, Acheta domesticus (L.)

1968 ◽  
Vol 46 (4) ◽  
pp. 695-698 ◽  
Author(s):  
J. E. McFarlane
Keyword(s):  
Dark Period ◽  
Continuous Light ◽  
Light Period ◽  
Acheta Domesticus ◽  
Diel Periodicity ◽  
Light Conditions ◽  
House Cricket ◽  
Male House

Male house crickets reared individually at 28 °C developed a diel periodicity in spermatophore formation, which consisted in loss of the spermatophore during the dark period and secretion during the light period. The periodicity became established only after most of the insects had formed at least two spermatophores in a random way with respect to light conditions. When periodicity was established, rearing the insects in continuous light resulted in the retention of the spermatophore by nearly all insects. Stridulation began in all experiments at the time of first spermatophore formation.

Effect of different combinations of light and dark regimes on the performance of egg lay events, fertility and plasma steroid hormones, during the ovulatory cycle in Peking ducks

1988 ◽  
Vol 111 (1) ◽  
pp. 99-105 ◽  
Author(s):  
M. A. Abdelrazik ◽  
Gh. A. El Sayiad ◽  
I. F. M. Marai ◽  
M. M. Soliman
Keyword(s):  
Inverse Relationship ◽  
Dark Period ◽  
Continuous Light ◽  
Light Period ◽  
Ovulatory Cycle ◽  
Shell Weight ◽  
Egg Weight ◽  
Plasma Progesterone ◽  
Pause Length ◽  
Photoperiodic Regime

SummaryDifferent photoperiodic treatments within 2 types of light dark cycles ranging from 24 to 30 h were applied to Peking ducks. The first consisted of constant photoperiods (1, 8L: 16D; 2, 14 L: 10D; 3, 18L:6D; 4, 14L: 13D; 5, 14L: 16D and 6, continuous light) and the second of intermittent cycles (1, 6L:2D:2L:14p; 2, 6L:4D:2L:12D; 3, 6L:6D:2L:10D; 4, 6L:8D:2L:8D and 5, 14L:½D:3½L:6D). The traits studied varied in response according to the photoperiodic regimes used. Rate of lay and eggs laid in the modal 8 h period increased with the duration of the light period in the cycle. Sequence lengths of 1–3 eggs were most frequent under all photoperiodic regimes (constant and intermittent). Length of intra-sequence interval (h) showed an inverse relationship with length of inter-sequence interval. A pause length of 2–4 days was the most frequent for all the different light-dark cycles. Egg weight was heavier in the second season than in the first when the light period of the photoperiodic regime was long. Weights of albumin and yolk showed similar trends to egg weight. The latter differences were significant, while shell weight differences were not significant. Plasma progesterone lvels were lowest in non-laying ducks. The highest values in laying ducks were before ovulation. The highest level of cortisol was shown during the last hours of the dark period. Differences from ovulatory cycle to another were observed.

Blockade of corticotropin-releasing hormone receptors reduces spontaneous waking in the rat

1998 ◽  
Vol 275 (3) ◽  
pp. R793-R802 ◽  
Author(s):  
Fang-Chia Chang ◽  
Mark R. Opp
Keyword(s):  
Hormone Receptors ◽  
Dark Period ◽  
Light Period ◽  
Corticotropin Releasing Hormone ◽  
Dark Cycle ◽  
Receptor Antagonists ◽  
Releasing Hormone ◽  
Waking And Sleep ◽  
Effective Doses ◽  
Time Courses

We have previously hypothesized that corticotropin-releasing hormone (CRH) is involved in the regulation of physiological waking. To further elucidate this role for CRH, we administered intracerebroventricularly into rats two specific CRH-receptor antagonists, α-helical CRH-(9—41) (α-hCRH) or astressin, and determined changes in electroencephalogram-defined waking and sleep. Our results indicate that both of these receptor antagonists reduce the amount of time spent awake in a dose-related manner when administered before the dark period of the light-dark cycle. However, the time courses for these effects differ between antagonists; effective doses of α-hCRH reduce waking during the first 2 h postinjection, whereas effective doses of astressin reduce waking during postinjection hours 7–12. In contrast to dark-onset administrations, the amount of waking is not altered by either CRH-receptor antagonist when administered before the light period. These results support our hypothesis that CRH contributes to the regulation of physiological waking, since interfering with the binding of CRH to its receptor reduces spontaneous waking.

Variations in Motor Activity and in Food and Water Intake over 24 h Periods in Pigs

1980 ◽  
Vol 95 (2) ◽  
pp. 371-380 ◽  
Author(s):  
D. L. Ingram ◽  
D. E. Walters ◽  
K. F. Legge
Keyword(s):  
Food Intake ◽  
Motor Activity ◽  
Water Consumption ◽  
Dark Period ◽  
Continuous Light ◽  
External Noise ◽  
Light Period ◽  
Food And Water Intake ◽  
Temperature Controlled ◽  
Weaner Pigs

SUMMARYGroups of weaner pigs, and single animals, were observed in a temperature-controlled room isolated from external noise and light for periods of up to 4 weeks. Continuous records were made of motor activity, food intake and water consumption.In the presence of a cycle of 12 h light and 12 h dark at 25 °C groups of pigs were most active in the light and took most of their food towards the end of the light period. Single pigs also tended to be more active in the light, but the rhythms were less marked, and one animal was most active during the dark period.In continuous light, rhythms of activity and ingestion tended to collapse after only a few days, particularly in pigs which were kept by themselves. When the ambient temperature was increased to 35 °C during 12 h light and decreased to 25 °C during 12 h dark, a group of pigs was most active in the dark.

A photosensitive daily rhythm in the female medaka, Oryzias latipes

1976 ◽  
Vol 54 (6) ◽  
pp. 852-856 ◽  
Author(s):  
Kenneth Ka-Sing Chan
Keyword(s):  
Adult Female ◽  
Ovarian Development ◽  
Dark Period ◽  
Continuous Light ◽  
Oryzias Latipes ◽  
Exposure Period ◽  
Light Period ◽  
Spawning Season ◽  
Daily Rhythm ◽  
Warm Temperature

Adult female medaka, Oryzias latipes, with regressed ovaries were exposed to 7 h of continuous light plus an additional hour of light at different times during the dark period of a 24-h cycle (7 + 1 light: 16 dark) at 24 ± 1 °C. When this additional hour of light falls on the 16th h, counting the onset of the light period as the 0 h, ovarian development was induced. This ovarian development is enhanced when the exposure period is increased and when the fish are preexposed to a warm temperature. The use of a photosensitive daily rhythm to measure photoperiod and to time the spawning season in the medaka is suggested.

Immunocytochemical studies on the behavior of RuBisCO and LHCP II during the cell cycle of synchronized Euglena gracilis

1990 ◽  
Vol 48 (3) ◽  
pp. 662-663
Author(s):  
Tetsuaki Osafune ◽  
Shuji Sumida ◽  
Tomoko Ehara ◽  
Eiji Hase ◽  
Jerome A. Schiff
Keyword(s):  
Cell Cycle ◽  
Immunoelectron Microscopy ◽  
Growth Phase ◽  
Euglena Gracilis ◽  
Dark Period ◽  
Light Period ◽  
Carboxylase Activity ◽  
Immunocytochemical Studies ◽  
Lhcp Ii

Changes in the morphology of pyrenoid and the distribution of RuBisCO in the chloroplast of Euglena gracilis were followed by immunoelectron microscopy during the cell cycle in a light (14 h)- dark (10 h) synchronized culture under photoautotrophic conditions. The imrnunoreactive proteins wereconcentrated in the pyrenoid, and less densely distributed in the stroma during the light period (growth phase, Fig. 1-2), but the pyrenoid disappeared during the dark period (division phase), and RuBisCO was dispersed throughout the stroma. Toward the end of the division phase, the pyrenoid began to form in the center of the stroma, and RuBisCO is again concentrated in that pyrenoid region. From a comparison of photosynthetic CO2-fixation with the total carboxylase activity of RuBisCO extracted from Euglena cells in the growth phase, it is suggested that the carboxylase in the pyrenoid functions in CO2-fixation in photosynthesis.

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