Are membrane properties essential for the circadian rhythm of Gonyaulax?

1984 ◽  
Vol 247 (2) ◽  
pp. R250-R256
Author(s):  
H. G. Scholubbers ◽  
W. Taylor ◽  
L. Rensing
Keyword(s):  
Circadian Rhythm ◽  
Phase Shift ◽  
Fluorescence Polarization ◽  
The Other ◽  
Membrane Properties ◽  
Response Curves ◽  
Whole Cells ◽  
Different Temperatures ◽  
Free Running ◽  
Free Running Period

Membrane properties of whole cells of Gonyaulax polyedra were measured by fluorescence polarization. Circadian changes of fluorescence polarization exist in exponentially growing cultures. They show an amplitude larger than that of stationary cultures, indicating that a part of the change is due to or amplified by an ongoing cell cycle. Measurements of parameters of the circadian glow rhythm were analyzed for possible correlation with the membrane data. Considerable differences (Q10 = 2.5-3.0) in fluorescence polarization were found in cultures kept at different temperatures ranging from 15 to 27.5 degrees C. The free-running period length at different temperatures, on the other hand, differed only slightly (Q10 = 0.9-1.1). Stationary cultures showed higher fluorescence polarization compared with growing cultures, whereas the free-running period lengths did not differ in cultures of various densities and growth rates. Temperature steps of different sign changed the fluorescence polarization slightly in different directions. The phase shift of 4-h pulses (-5, -9, +7 degrees C) resulted in maximal phase advances of 4, 6, and 2 h, respectively. The phasing of the phase-response curves was identical in all these experiments, a finding not to be expected if the pulses act via the measured membrane properties. Pulses of drugs that change the fluorescence polarization (e.g., chlorpromazine and lidocaine) did not or only slightly phase-shift the circadian rhythm.

Effects of aging on entrainment and rate of resynchronization of circadian locomotor activity

1992 ◽  
Vol 263 (5) ◽  
pp. R1099-R1103 ◽  
Author(s):  
P. C. Zee ◽  
R. S. Rosenberg ◽  
F. W. Turek
Keyword(s):  
Circadian Rhythm ◽  
Locomotor Activity ◽  
Activity Rhythm ◽  
Phase Advance ◽  
Middle Aged ◽  
Age Related ◽  
Free Running ◽  
Effects Of Aging ◽  
Free Running Period ◽  
Related Phase

The phase angle of entrainment of the circadian rhythm of the locomotor activity rhythm to a light-dark (LD) cycle was examined in young (2-5 mo old) and middle-aged (13-16 mo old) hamsters. An age-related phase advance in the onset of locomotor activity relative to lights off was seen during stable entrainment to a 14:10-h LD cycle. In addition, the effects of age on the rate of reentrainment of the circadian rhythm of locomotor activity were examined by subjecting young and middle-aged hamsters to either an 8-h advance or delay shift of the LD cycle. Middle-aged hamsters resynchronized more rapidly after a phase advance of the LD cycle than did young hamsters, whereas young hamsters were able to phase delay more rapidly than middle-aged hamsters. The age-related phase advance of activity onset under entrained conditions, and the alteration of responses in middle-aged hamsters reentraining to a phase-shifted LD cycle, may be due to the shortening of the free-running period of the circadian rhythm of locomotor activity with advancing age that has previously been observed in this species.

Extraretinal photoreception in the lizard Sceloporus occidentalis: phase response curve

1985 ◽  
Vol 248 (4) ◽  
pp. R407-R414
Author(s):  
H. Underwood
Keyword(s):  
Phase Response Curve ◽  
Circadian System ◽  
Phase Response ◽  
Fluorescent Light ◽  
Response Curves ◽  
Sceloporus Occidentalis ◽  
Light Pulses ◽  
Threefold Increase ◽  
Free Running ◽  
Free Running Period

All submammalian vertebrates have extraretinal photoreceptors (ERR) that can mediate entrainment of circadian rhythms to 24-h light-dark (LD) cycles. Phase response curves (PRC) for 6-h fluorescent light pulses were generated for lizards (Sceloporus occidentalis) previously subjected to sectioning of both optic nerves (ONX). The PRC for ONX lizards (only ERRs present) shows a threefold increase in the amplitude of both the advance and delay portions of the PRC compared with a PRC previously generated for sighted S. occidentalis. Also, in contrast to sighted lizards the area of the advance part of the PRC of ONX lizards is greater than the delay portion. Consistent with the shape of the respective PRCs in ONX vs. sighted lizards are the following facts. 1) The range of entrainment to LD cycles is greater in ONX lizards; some sighted lizards free-ran when exposed to LD 6:21.5 or LD 6:23.5 but entrained after ONX lizards reentrained to an 8-h shift in the phase of a LD 6:18 cycle significantly faster than sighted lizards. 3) Forty-two percent of ONX lizards showed a shorter free-running period (tau) in LL than DD, whereas 90% of sighted lizards showed a longer free-running period in LL than in DD. In those lizards in which tau LL greater than tau DD, the the average tau change in ONX lizards in was significantly less than that observed in sighted lizards. These results are consistent with the hypothesis that the eyes have an "inhibitory" role in the circadian system of S. occidentalis.

Regularly scheduled voluntary exercise synchronizes the mouse circadian clock

1991 ◽  
Vol 261 (4) ◽  
pp. R928-R933 ◽  
Author(s):  
D. M. Edgar ◽  
W. C. Dement
Keyword(s):  
Circadian Rhythms ◽  
Phase Shift ◽  
Circadian Clock ◽  
Wheel Running ◽  
External Environment ◽  
Voluntary Exercise ◽  
Wheel Rotation ◽  
Exercise Activity ◽  
Free Running ◽  
Free Running Period

Circadian rhythm entrainment has long been thought to depend exclusively on periodic cues in the external environment. However, evidence now suggests that appropriately timed vigorous activity may also phase shift the circadian clock. Previously it was not known whether levels of exercise/activity associated with spontaneous behavior provided sufficient feedback to phase shift or synchronize circadian rhythms. The present study investigated this issue by monitoring the sleep-wake, drinking, and wheel-running circadian rhythms of mice (Mus musculus) during unrestricted access to running wheels and when free wheel rotation was limited to either 12- or 6-h intervals with a fixed period of 24 h. Wheel rotation was controlled remotely. Mice spontaneously ran in wheels during scheduled access, and free-running sleep-wake and drinking circadian rhythms became entrained to scheduled exercise in 11 of 15 animals. However, steady-state entrainment was achieved only when exercise commenced several hours into the subjective night. The temporal placement of running during entrainment was related (r = 0.7003, P less than 0.02) to free-running period before entrainment. Mice with a free-running period less than 23.0 h did not entrain but exhibited relative coordination between free-running variables and the wheel availability schedule. Thus the circadian timekeeping system responds to temporal feedback arising from the timing of volitional exercise/activity, suggesting that the biological clock not only is responsive to periodic geophysical events in the external environment but also derives physiological feedback from the spontaneous activity behaviors of the organism.

Inhibitors of protein synthesis on 80S ribosomes phase shift the Gonyaulax clock

1982 ◽  
Vol 97 (1) ◽  
pp. 121-136
Author(s):  
W. R. Taylor ◽  
J. C. Dunlap ◽  
J. W. Hastings
Keyword(s):  
Protein Synthesis ◽  
Circadian Rhythm ◽  
Circadian Rhythms ◽  
Phase Shift ◽  
Phase Shifts ◽  
Circadian Cycle ◽  
Response Curves ◽  
80S Ribosome ◽  
Strong Phase ◽  
Additional Support

One-hour pulses of anisomycin (0.3 microM), streptimidone (30 microM) and cycloheximide (5 microM) caused strong phase-shifts (either advances or delays, of up to 12 h) in the circadian rhythm of the bioluminescence glow in the marine photosynthetic dinoflagellate, Gonyaulax polyedra. Similar pulses of emetine (0.1-100 microM) caused small (less than 4 h) phase shifts. Drug pulses have quantitatively different effects when applied at different phases of the circadian cycle, thus giving rise to ‘phase response curves’ (PRC's). The results lend additional support to the generalization, based on results from several different organisms, that 80s ribosome protein synthesizing system is of key importance in the mechanism responsible for circadian rhythms.

Restricted daily feeding during nursing period resets circadian locomotor rhythm of infant rats

1987 ◽  
Vol 252 (2) ◽  
pp. R262-R268
Author(s):  
S. Honma ◽  
K. Honma ◽  
T. Hiroshige
Keyword(s):  
Circadian Rhythm ◽  
Fixed Time ◽  
Feeding Time ◽  
Control Zone ◽  
Locomotor Rhythm ◽  
Daily Feeding ◽  
Rat Pups ◽  
Free Running ◽  
Phase Setting ◽  
Free Running Period

Phase setting of the circadian rhythm by restricted daily feeding (RF) was examined in rat pups. Feeding of virgin, pregnant, and nursing rats together with pups was restricted to 4 h at a fixed time of the day. Phases of the circadian rhythm developed in neonatally blinded pups were measured on the day of weaning to evaluate the effect of RF on phase setting. The activity onset and offset of the locomotor rhythm were used for the phase reference. In blinded pups born and raised under ad libitum feeding, the phase at weaning was a function of the free-running period measured after weaning and located in a narrow range (control zone). When RF was imposed from 2 wk prior to the conception (C) until weaning (3w), the pups phases were located outside the control zone and related to the feeding time. To identify the period in which the phase setting is effective, RF was imposed during 5 different periods (C-0w, C-1w, C-2w, 2-6w, and 3-6w). The circadian rhythm of all pups in the C-2w group and some in the C-1w was phase set, but those in other groups were not affected. It is concluded that RF imposed during the early nursing period is capable of phase setting the circadian system of blinded infant rats.x

Effect of D2O on the Circadian Rhythm of Petal Movement of Kalanchoe

1974 ◽  
Vol 29 (1-2) ◽  
pp. 36-38 ◽  
Author(s):  
Albrecht Maurer ◽  
Wolfgang Engelmann
Keyword(s):  
Circadian Rhythm ◽  
Heavy Water ◽  
Phase Shifts ◽  
Circadian Cycle ◽  
Free Running ◽  
Free Running Period

Abstract D2O lengthens the free running period of the circadian petal movement of isolated Kalanchoe flowers by 1.6% per 10% heavy water. This corresponds to findings reported in the literature for other organisms. 100% D2O administered in the form of 4 hour pulses at various phases of the circadian cycle lead to phase responses zero to maximally 1.5 hour delays. No advancing phase shifts occur. Possible ways in which lengthening of the period occurs are discussed.

Entrainment of the circadian rhythm from the eye of Aplysia: role of serotonin

1982 ◽  
Vol 242 (3) ◽  
pp. R326-R332
Author(s):  
G. Corrent ◽  
A. Eskin ◽  
I. Kay
Keyword(s):  
Circadian Rhythm ◽  
Phase Shift ◽  
Transmitter Release ◽  
Response Curve ◽  
Phase Shifts ◽  
Phase Response ◽  
Phase Shifting ◽  
Response Curves ◽  
Light Pulses

The finding that serotonin (5-HT) treatments as short as 1.5 h in duration produce phase shifts in a circadian rhythm from the isolated eye of Aplysia suggested that release of 5-HT was part of an ocular entrainment pathway. Since light cycles entrain this rhythm, we compared phase shifting by 5-HT and by light. The similarity in the shapes of the phase-response curves for 5-HT and light pulses indicates that 5-HT treatments are capable of entraining the rhythm. Also, "skeleton" 5-HT treatments phase shift as well as continuous 5-HT treatments. However, 5-HT does not appear to mediate the phase shifts produced by light, since 1) treatments that should block transmitter release do not change the phase shifts produced by light pulses; 2) the response curves of 5-HT and light pulses are displaced by 12 h relative to one another on the phase axis of the response curve; and 3) light-induced phase shifts are apparent almost immediately, whereas 5-HT-induced phase shifts become evident only about 24 h after 5-HT treatment. The eye appears to contain two independent entrainment pathways, one for light and one utilizing 5-HT.

Circadian Rhythm of Locomotion and its Temperature Dependence in Blattella Germanica

1971 ◽  
Vol 54 (1) ◽  
pp. 187-198
Author(s):  
HANS DREISIG ◽  
ERIK TETENS NIELSEN
Keyword(s):  
Circadian Rhythm ◽  
Light Intensity ◽  
Temperature Dependence ◽  
Blattella Germanica ◽  
Temperature Dependent ◽  
Continuous Darkness ◽  
Expected Time ◽  
Different Temperatures ◽  
Free Running ◽  
Increasing Temperature

1. The activity in Blattella germanica was investigated under standard conditions. Periods of latency and increment were recognized. 2. The free-running rhythm in continuous darkness was determined at different temperatures and showed about the same period. The free-running rhythm in continous light could not be determined unless the light intensity was extremely low. 3. The period of activity was not released immediately after a change from light to darkness if this was advanced in relation to the normal time. The activity was then only slightly advanced. 4. Delay of the onset of darkness caused the activity to diminish gradually after the usual time of change from light to dark. 5. If the temperature was lowered some time before the expected time of activity in continuous darkness the activity was advanced much more than normally. If the temperature was raised the activity was delayed. 6. Based upon these and other studies, a theory is advanced which explains the activity rhythms in insects as being the result of the interaction between a gradually increasing, temperature-dependent sensitization and different thresholds of release determined by light and temperature. A theory is propounded concerning the temperature-independence of the free-running rhythm in continuous darkness, assuming a temperature-dependent threshold of release.

Circadian pacemakers in lizards: phase-response curves and effects of pinealectomy

1983 ◽  
Vol 244 (6) ◽  
pp. R857-R864 ◽  
Author(s):  
H. Underwood
Keyword(s):  
Continuous Light ◽  
Phase Response ◽  
Fluorescent Light ◽  
Response Curves ◽  
Continuous Darkness ◽  
Phase Response Curves ◽  
Light Pulses ◽  
Running Activity ◽  
Free Running ◽  
Free Running Period

Phase-response curves (PRCs) for 6-h fluorescent light pulses are described for both intact (sham-pinealectomized) and pinealectomized iguanid lizards (Sceloporus occidentalis). Although strongly diurnal in habit the PRC for intact lizards is more typical of those seen in nocturnal rodents. Other "nocturnal" characteristics of this lizard include the fact that the average free-running period (tau) is less than 24 h and the average tau in continuous light is longer than that observed in continuous darkness. The PRC for pinealectomized lizards is greatly distorted relative to that obtained from intact lizards. This "distortion" is discussed in terms of the role of the pineal as a coupling device or as a pacemaker within a multioscillator circadian system. In some individuals pinealectomy was also associated with 1) increased instability in free-running activity rhythms or arrhythmicity and 2) nocturnal entrainment to LD 12:12.

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