Neuropeptide F immunoreactive clock neurons modify evening locomotor activity and free-running period in Drosophila melanogaster

2012 ◽  
Vol 520 (5) ◽  
pp. 970-987 ◽  
Author(s):  
Christiane Hermann ◽  
Taishi Yoshii ◽  
Verena Dusik ◽  
Charlotte Helfrich-Förster
Keyword(s):  
Drosophila Melanogaster ◽  
Locomotor Activity ◽  
Free Running ◽  
Neuropeptide F ◽  
Free Running Period

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.

scholarly journals per mRNA cycling is locked to lights-off under photoperiodic conditions that support circadian feedback loop function.

1996 ◽  
Vol 16 (8) ◽  
pp. 4182-4188 ◽  
Author(s):  
J Qiu ◽  
P E Hardin
Keyword(s):  
Locomotor Activity ◽  
Negative Feedback ◽  
Reference Point ◽  
Feedback Loop ◽  
Negative Feedback Loop ◽  
Loop Function ◽  
Activity Rhythms ◽  
Free Running ◽  
Circadian Behavior ◽  
Free Running Period

Circadian fluctuations in per mRNA and protein are central to the operation of a negative feedback loop that is necessary for setting the free-running period and for entraining the circadian oscillator to light-dark cycles. In this study, per mRNA cycling and locomotor activity rhythms were measured under different light and dark cycling regimes to determine how photoperiods affect the molecular feedback loop and circadian behavior, respectively. These experiments reveal that per mRNA peaks in abundance 4 h after lights-off in photoperiods of < or = 16 h, that, phase shifts in per mRNA cycling and behavioral rhythmicity occur rapidly after flies are transferred from one photoperiod to another, and that photoperiods longer than 20 h abolish locomotor activity rhythms and leave per mRNA at a median constitutive level. These results indicate that the per feedback loop uses lights-off as a phase reference point and suggest (along with previous findings for per01 and tim01) that per mRNA cycling is not regulated via simple negative feedback from the per protein.

scholarly journals Coupling effect of locomotor activity on the rat’s circadian system

1998 ◽  
Vol 275 (2) ◽  
pp. R580-R587 ◽  
Author(s):  
Pedro Lax ◽  
Salvador Zamora ◽  
Juan A. Madrid
Keyword(s):  
Locomotor Activity ◽  
Wheel Running ◽  
Coupling Effect ◽  
Red Light ◽  
Bright Light ◽  
Circadian System ◽  
Circadian Rhythmicity ◽  
Lighting Conditions ◽  
Free Running ◽  
Free Running Period

Exercise is recognized to affect circadian rhythmicity in a variety of ways. It masks the expression of other behavioral and physiological rhythms, entrains the master pacemaker, and influences the free-running period of other rhythms. In this paper we study the influence of exercise on the organization of the timing system by analyzing the effect of voluntary locomotor activity on the circadian feeding behavior of rats subjected to different lighting conditions. The availability of wheel running prevented loss of feeding circadian rhythmicity under constant bright light (LL) but did not elicit any circadian pattern in rats showing a previous arrhythmic pattern. Under dim red light (DR), the rhythm was more pronounced in exercising than in sedentary rats, while wheel-running availability accelerated the emergence of circadian rhythmicity in arrhythmic animals that were moved from LL to DR. These results can be explained by the existence of a positive feedback loop between physical exercise and its pacemaker and also suggest that exercise changes the functioning of the circadian system to facilitate the emergence of circadian rhythms in previously arrhythmic animals.

Circadian variation in the behaviour and physiology of Bulinus tropicus (Gastropoda: Pulmonata)

1983 ◽  
Vol 61 (4) ◽  
pp. 909-914 ◽  
Author(s):  
M. Asghar Chaudhry ◽  
Elfed Morgan
Keyword(s):  
Locomotor Activity ◽  
Circadian Variation ◽  
Phase Relationship ◽  
Ammonia Excretion ◽  
Freshwater Snail ◽  
Egg Laying ◽  
Autocorrelation Analysis ◽  
Free Running ◽  
Activity Cycles ◽  
Free Running Period

Locomotor activity, feeding, defaecation, excretion, oviposition, and hatching have been studied over the circadian span for specimens of the tropical freshwater snail Bulinus tropicus entrained to a 8.5 h light: 15.5 h dark photoperiod. With the exception of defaecation, which is apparently arrhythmic, the activities studied followed a diurnal pattern with an approximately parallel phase relationship over the circadian period. The rhythms persist in constant conditions and periodogram and autocorrelation analysis showed the feeding and locomotor activity cycles to have an almost identical free-running period of approximately 23.5 h. In contrast to the rhythm of ammonia excretion, which is maximal early during the light or subjective light period, oviposition in B. tropicus follows a bimodal pattern and the hatching times tend to be similarly distributed throughout the day. The hatching behaviour of B. globosus is similarly bimodal, although this species shows only a single peak of egg laying at about midday. A multiple oscillator mechanism is suggested to account for the results.

scholarly journals A circadian clock in a nonphotosynthetic prokaryote

2021 ◽  
Vol 7 (2) ◽  
pp. eabe2086
Author(s):  
Zheng Eelderink-Chen ◽  
Jasper Bosman ◽  
Francesca Sartor ◽  
Antony N. Dodd ◽  
Ákos T. Kovács ◽  
...  
Keyword(s):  
Temperature Compensation ◽  
Temporal Structure ◽  
Bacterial Biofilm ◽  
Circadian Clocks ◽  
Industrial Processes ◽  
Free Living ◽  
Considerable Potential ◽  
Free Running ◽  
Free Running Period ◽  
Constant Dark

Circadian clocks create a 24-hour temporal structure, which allows organisms to occupy a niche formed by time rather than space. They are pervasive throughout nature, yet they remain unexpectedly unexplored and uncharacterized in nonphotosynthetic bacteria. Here, we identify in Bacillus subtilis circadian rhythms sharing the canonical properties of circadian clocks: free-running period, entrainment, and temperature compensation. We show that gene expression in B. subtilis can be synchronized in 24-hour light or temperature cycles and exhibit phase-specific characteristics of entrainment. Upon release to constant dark and temperature conditions, bacterial biofilm populations have temperature-compensated free-running oscillations with a period close to 24 hours. Our work opens the field of circadian clocks in the free-living, nonphotosynthetic prokaryotes, bringing considerable potential for impact upon biomedicine, ecology, and industrial processes.

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