Motor activity correlates negatively with free-running period, while positively with serotonin contents in SCN in free-running rats

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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Are membrane properties essential for the circadian rhythm of Gonyaulax?

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1984.247.2.r250 ◽

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.

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Gonadal hormones organize and modulate the circadian system of the rat

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1981.241.1.r62 ◽

1981 ◽

Vol 241 (1) ◽

pp. R62-R66 ◽

Cited By ~ 11

Author(s):

H. E. Albers

Keyword(s):

Testosterone Propionate ◽

Wheel Running ◽

Activity Rhythm ◽

Gonadal Hormones ◽

Circadian System ◽

Female Rats ◽

Constant Darkness ◽

Before And After ◽

Free Running ◽

Free Running Period

The circadian wheel-running rhythms of gonadectomized adult male, female, and perinatally androgenized female rats, maintained in constant darkness, were examined before and after implantation of Silastic capsules containing cholesterol (C) or estradiol-17 beta (E). The free-running period of the activity rhythm (tau) before capsule implantation tended to be shorter in animals exposed to perinatal androgen. Administration of C did not reliably alter tau in any group. E significantly shortened tau in 100% of females injected with oil on day 3 of life. In females, injected with 3.5 micrograms testosterone propionate on day 3, and males, E shortened or lengthened tau, with the direction and magnitude of this change in tau inversely related to the length of the individual's pretreatment tau. These data indicate that the presence of perinatal androgen does not eliminate the sensitivity of the circadian system of the rat to estrogen, since estrogen alters tau in a manner that depends on its pretreatment length.

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

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1992.263.5.r1099 ◽

1992 ◽

Vol 263 (5) ◽

pp. R1099-R1103 ◽

Cited By ~ 7

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.

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

The Journal of Comparative Neurology ◽

10.1002/cne.22742 ◽

2012 ◽

Vol 520 (5) ◽

pp. 970-987 ◽

Cited By ~ 48

Author(s):

Christiane Hermann ◽

Taishi Yoshii ◽

Verena Dusik ◽

Charlotte Helfrich-Förster

Keyword(s):

Drosophila Melanogaster ◽

Locomotor Activity ◽

Free Running ◽

Neuropeptide F ◽

Free Running Period

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Organization of rat circadian rhythms during daily infusion of melatonin or S20098, a melatonin agonist

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1999.277.3.r812 ◽

1999 ◽

Vol 277 (3) ◽

pp. R812-R828 ◽

Cited By ~ 14

Author(s):

B. Pitrosky ◽

R. Kirsch ◽

A. Malan ◽

E. Mocaer ◽

P. Pevet

Keyword(s):

Body Temperature ◽

Circadian Rhythms ◽

Phase Response Curve ◽

Constant Darkness ◽

Time Interval ◽

General Activity ◽

Activity Peak ◽

Free Running ◽

Wheel Activity ◽

Free Running Period

Daily administration of melatonin or S20098, a melatonin agonist, is known to entrain the free-running circadian rhythms of rats. The effects of the duration of administration on entrainment were studied. The animals demonstrated free-running circadian rhythms (running-wheel activity, body temperature, general activity) in constant darkness. Daily infusions of melatonin or S20098 for 1, 8, or 16 h entrained the circadian rhythms to 24 h. Two daily infusions of 1 h (separated by 8 h) entrained the activity peak within the shorter time interval. The entraining properties of melatonin and S20098 were similar and were affected neither by pinealectomy nor by infusion of 1- or 8-h duration. However, with 16-h infusion, less than half of the animals became entrained. Once entrained, the phase angle between the onset of infusion and the rhythms (onset of activity or acrophase of body temperature) increased with the duration of infusion. Before entrainment, the free-running period increased with the duration of infusion, an effect that was not predictable from the phase response curve.

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Unexpected Geographic Variability of the Free Running Period in the Linden Bug Pyrrhocoris apterus

Journal of Biological Rhythms ◽

10.1177/0748730416671213 ◽

2016 ◽

Vol 31 (6) ◽

pp. 568-576 ◽

Cited By ~ 17

Author(s):

Lenka Pivarciova ◽

Hanka Vaneckova ◽

Jan Provaznik ◽

Bulah Chia-hsiang Wu ◽

Martin Pivarci ◽

...

Keyword(s):

Technological Progress ◽

Genetic Basis ◽

Model Organisms ◽

Geographic Variability ◽

Model Species ◽

Pyrrhocoris Apterus ◽

Free Running ◽

Field Lines ◽

Free Running Period ◽

Remarkable Progress

Circadian clocks keep organisms in synchrony with external day-night cycles. The free running period (FRP) of the clock, however, is usually only close to—not exactly—24 h. Here, we explored the geographical variation in the FRP of the linden bug, Pyrrhocoris apterus, in 59 field-lines originating from a wide variety of localities representing geographically different environments. We have identified a remarkable range in the FRPs between field-lines, with the fastest clock at ~21 h and the slowest close to 28 h, a range comparable to the collections of clock mutants in model organisms. Similarly, field-lines differed in the percentage of rhythmic individuals, with a minimum of 13.8% and a maximum of 86.8%. Although the FRP correlates with the latitude and perhaps with the altitude of the locality, the actual function of this FRP diversity is currently unclear. With the recent technological progress of massive parallel sequencing and genome editing, we can expect remarkable progress in elucidating the genetic basis of similar geographic variants in P. apterus or in similar emerging model species of chronobiology.

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Variation in the naturally occurring rhythm of the estuarine amphipod, Corophium volutator (Pallas)

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315400071253 ◽

1983 ◽

Vol 63 (4) ◽

pp. 833-850 ◽

Cited By ~ 43

Author(s):

Walter F. Holmström ◽

Elfed Morgan

Keyword(s):

Activity Rhythm ◽

Time Lapse ◽

Early Summer ◽

Corophium Volutator ◽

Use Of Time ◽

Recording Conditions ◽

Free Running ◽

Endogenous Activity ◽

Free Running Period ◽

Time Lapse Photography

The endogenous activity rhythm of the estuarine amphipod Corophium volutator has been studied by direct observation and with the use of time lapse photography. The rhythm persists under constant conditions having a free running period of between 12 and 13 h, and with activity maxima occurring during the early ebb. Freshly collected animals show a rhythm which is modulated on a semi-lunar basis, the activity maxima being attenuated during the neap tide periods, and the rhythm has also been found to vary in definition throughout the year. The activity pattern is most clearly denned in early summer and autumn, the population becoming arrhythmic during the winter months. The rhythm is relatively unaffected by the ambient light intensity and temperature of the recording conditions, and is evident in all post-natal stages of development. The possibility of mutual entrainment is discussed.

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