scholarly journals Phenotypic and genetic analysis of Clock, a new circadian rhythm mutant in Drosophila melanogaster.

Genetics ◽  
1990 ◽  
Vol 125 (3) ◽  
pp. 557-578 ◽  
Author(s):  
M S Dushay ◽  
R J Konopka ◽  
D Orr ◽  
M L Greenacre ◽  
C P Kyriacou ◽  
...  
Keyword(s):  
Response Curve ◽  
Phase Response Curve ◽  
Activity Rhythm ◽  
Courtship Song ◽  
Activity Rhythms ◽  
Light Pulses ◽  
Essentially Normal ◽  
Running Activity ◽  
Short Period ◽  
Free Running

Abstract Clock is a semidominant X-linked mutation that results in shortening the period of Drosophila melanogaster's free-running locomotor activity rhythm from ca. 24.0 to ca. 22.5 hr. This mutation similarly shortened the phase response curve, determined by resetting activity rhythms with light pulses. Eclosion peaks for Clk cultures were separated by only 22.5 hr instead of the normal 24 hr. Clk was mapped close to, but separable from, another rhythm mutation--period01--by recombination. The estimated distance between these two mutations was short enough to suggest that Clk could be a per allele. If this is the case, the new mutant is unique in that it, unlike other per variants, is associated with essentially normal 1-min courtship song rhythms when Clk is expressed in males. Also, the new rhythm variant could not, in contrast to a short-period per mutation, have its effects on free-running activity rhythms uncovered by deletions. This result, and the lack of coverage of Clk's effects by duplications, suggest that it is not a simple hypomorphic or amorphic mutation.

Notizen: Weak and Strong Phase Shifting in the Activity Rhythm of Leucophaea maderae (Blaberidae)after Light Pulses of High Intensity

1977 ◽  
Vol 32 (5-6) ◽  
pp. 464-465 ◽  
Author(s):  
Gottfried Wiedenmann
Keyword(s):  
High Intensity ◽  
Response Curve ◽  
Phase Response Curve ◽  
Activity Rhythm ◽  
Phase Response ◽  
Strong Phase ◽  
Light Pulses ◽  
Leucophaea Maderae ◽  
Running Activity ◽  
High Intensity Light

Abstract In the running activity of the cockroach Leucophaea maderae a strong phase response curve is found when using high intensity light pulses (80 000 lx and about 12 hours duration). The phase response curve has an unsymmetric shape: delays are larger than advances. The phase jump lies about 2 hours after subjective midnight.

Administering triazolam on a circadian basis entrains the activity rhythm of hamsters

1989 ◽  
Vol 256 (3) ◽  
pp. R639-R645
Author(s):  
O. Van Reeth ◽  
F. W. Turek
Keyword(s):  
Response Curve ◽  
Wheel Running ◽  
Phase Response Curve ◽  
Activity Rhythm ◽  
Phase Relationship ◽  
Phase Shifts ◽  
Phase Response ◽  
Light Pulses ◽  
Circadian Time ◽  
Free Running

A single injection of the short-acting benzodiazepine, triazolam, can induce permanent phase shifts in the circadian rhythm of locomotor activity in free-running hamsters, with the direction and magnitude of the phase shifts being dependent on the circadian time of treatment. The shape of the "phase-response curve" to triazolam injections is totally different from that for light pulses. These findings raise the possibility that repeated injections of triazolam on a circadian basis might be capable of entraining the circadian pacemaker underlying the activity rhythm of hamsters and that the entrainment pattern might differ from that observed in animals entrained to light pulses. To test this hypothesis, blind hamsters received intraperitoneal injections of triazolam (or vehicle) every 23.34, 23.72, 24.00 or 24.66 h for 19-20 days, and the effect of these injections on the period of the rhythm of wheel-running behavior was determined during and after treatment. Repeated injections of 0.1 mg triazolam at these time intervals resulted in the entrainment of the activity rhythm in 36 of 40 animals, whereas 0 of 40 animals entrained to vehicle injections. Importantly, the phase relationship between triazolam injections and the circadian activity rhythm was dependent on the period of drug treatment and could be predicted from the phase-response curve to single injections of triazolam. These phase relationships are dramatically different from those observed between the activity rhythm and 1-h light pulses presented at similar circadian intervals.(ABSTRACT TRUNCATED AT 250 WORDS)

Melatonin and activity rhythm responses to light pulses in mice with the Clock mutation

2003 ◽  
Vol 284 (5) ◽  
pp. R1231-R1240 ◽  
Author(s):  
David J. Kennaway ◽  
Athena Voultsios ◽  
Tamara J. Varcoe ◽  
Robert W. Moyer
Keyword(s):  
Wheel Running ◽  
Activity Rhythm ◽  
Mutant Mice ◽  
Constant Darkness ◽  
Wild Type ◽  
Continuous Darkness ◽  
Light Pulses ◽  
Essentially Normal ◽  
Running Activity ◽  
Wheel Running Activity

Melatonin and wheel-running rhythmicity and the effects of acute and chronic light pulses on these rhythms were studied in Clock Δ19 mutant mice selectively bred to synthesize melatonin. Homozygous melatonin-proficient Clock Δ19 mutant mice ( Clock Δ19/Δ19 -MEL) produced melatonin rhythmically, with peak production 2 h later than the wild-type controls (i.e., just before lights on). By contrast, the time of onset of wheel-running activity occurred within a 20-min period around lights off, irrespective of the genotype. Melatonin production in the mutants spontaneously decreased within 1 h of the expected time of lights on. On placement of the mice in continuous darkness, the melatonin rhythm persisted, and the peak occurred 2 h later in each cycle over the first two cycles, consistent with the endogenous period of the mutant. This contrasted with the onset of wheel-running activity, which did not shift for several days in constant darkness. A light pulse around the time of expected lights on followed by constant darkness reduced the expected 2-h delay of the melatonin peak of the mutants to ∼1 h and advanced the time of the melatonin peak in the wild-type mice. When the Clock Δ19/Δ19 -MEL mice were maintained in a skeleton photoperiod of daily 15-min light pulses, a higher proportion entrained to the schedule (57%) than melatonin-deficient mutants (9%). These results provide compelling evidence that mice with the Clock Δ19 mutation express essentially normal rhythmicity, albeit with an underlying endogenous period of 26–27 h, and they can be entrained by brief exposure to light. They also raise important questions about the role of Clock in rhythmicity and the usefulness of monitoring behavioral rhythms compared with hormonal rhythms.

Dark pulses affect the circadian rhythm of activity in hamsters kept in constant light

1982 ◽  
Vol 242 (1) ◽  
pp. R44-R50 ◽  
Author(s):  
G. B. Ellis ◽  
R. E. McKlveen ◽  
F. W. Turek
Keyword(s):  
Response Curve ◽  
Phase Response Curve ◽  
Circadian System ◽  
Constant Light ◽  
Constant Darkness ◽  
Light Pulses ◽  
Subjective Night ◽  
Free Running ◽  
Male Golden Hamsters ◽  
Formal Properties

We compared the effects of light pulses in constant darkness (DD) and dark pulses in constant light (LL) on the free-running rhythm of locomotor activity in male golden hamsters. Light pulses yielded advances, delays, or no change in the rhythm of activity. These data conform to a typical phase-response curve; this curve was unaffected by pinealectomy. Dark pulses occurring either late in the subjective night or early in the subjective day had little effect. In contrast, dark pulses occurring either late in the subjective day or early in the subjective night altered the rhythm in one of three ways: advance of the rhythm; splitting into two components; or induction of a new component, in phase with the pulse. Because dark pulses in LL perturb the circadian system in a different manner than do light pulses in DD, they may have value in identifying heretofore unknown aspects of circadian systems. As such, the use of dark pulses to perturb circadian rhythmicity will be a useful tool in examining the formal properties of circadian systems.

Circadian rhythms in blinded rats: correlation between pineal and activity cycles

1978 ◽  
Vol 234 (3) ◽  
pp. R110-R114
Author(s):  
C. R. Pohl ◽  
F. P. Gibbs
Keyword(s):  
Pineal Gland ◽  
Activity Rhythm ◽  
Diurnal Rhythms ◽  
Light Cycle ◽  
Activity Phase ◽  
Running Activity ◽  
Free Running ◽  
Activity Cycles ◽  
Rat Pineal Gland ◽  
Sampling Times

The rat pineal gland exhibits diurnal rhythms in levels of N-acetyltransferase activity and its substrate serotonin. We attempted to demonstrate the endogenous nature of these changes by measuring the pineal enzyme and its substrate in rats blinded for 37 and 60 days. In order to determine the proper sampling times for these one-time, terminal measurements, the running activity rhythm of each rat was monitored continuously and the animals were killed at either midrest or midrun. Circadian changes of pineal N-acetyltransferase and serotonin were demonstrated, with enzyme levels high and substrate content low during midrun. Absolute values during each activity phase were similar to those of control rats entrained to a light cycle (LD 12:12). Levels of the pineal constituents were unrelated to local time. These results suggest that rats blinded for up to 60 days maintain their free-running pineal rhythms with undamped amplitudes and in synchronization with the activity rhythm.

scholarly journals A Phase Response Curve to Single Bright Light Pulses in Human Subjects

2003 ◽  
Vol 549 (3) ◽  
pp. 945-952 ◽  
Author(s):  
Sat Bir S. Khalsa ◽  
Megan E. Jewett ◽  
Christian Cajochen ◽  
Charles A. Czeisler
Keyword(s):  
Response Curve ◽  
Phase Response Curve ◽  
Human Subjects ◽  
Bright Light ◽  
Phase Response ◽  
Light Pulses

scholarly journals The Effects of Intraventricular Carbachol Injections on the Free-Running Activity Rhythm of the Hamster

1988 ◽  
Vol 3 (4) ◽  
pp. 333-348 ◽  
Author(s):  
Johanna H. Meijer ◽  
E. van der Zee ◽  
M. Dietz
Keyword(s):  
Activity Rhythm ◽  
Running Activity ◽  
Free Running

Comment: Why do beavers exhibit free-running activity rhythms in winter?

1995 ◽  
Vol 73 (11) ◽  
pp. 2167-2168
Author(s):  
Peter J. Marchand
Keyword(s):  
Snow Cover ◽  
Activity Rhythms ◽  
Running Activity ◽  
Free Running

Measurements of irradiance in northern ponds under ice and snow cover raise questions as to why beavers often show free-running activity rhythms in winter.

Temperature Sensitive Events between Photoreceptor and Circadian Clock?

1975 ◽  
Vol 30 (3-4) ◽  
pp. 240-244 ◽  
Author(s):  
Ursula Hamm ◽  
M Aroli ◽  
K Chandrashekaran ◽  
W Olfgang Engelmann
Keyword(s):  
Low Temperature ◽  
Response Curve ◽  
Time Course ◽  
Phase Response Curve ◽  
Phase Response ◽  
Phase Shifting ◽  
Wave Form ◽  
Temperature Sensitive ◽  
Slowing Down ◽  
Light Pulses

Abstract The phase shifting action of low temperature pulses of 6 °C and 2 h duration administered to the various phases of the Drosophila pseudoobscura circadian rhythm and the action of light pulses given 30 min after the beginning of these low temperature pulses have been investigated. The phase response curve obtained from experiments with light pulses during low temperature cannot be ex­ plained on the basis of a straightforward and sequential phase shifting of the oscillation by the various transitions in the pulses. The response curve, after the slight phase shifting action of the temperature pulses is corrected for, resembles the standard phase response curve 4 for light pulses (at 20 °C) in its wave form but not in its time course. Our curve is shifted in time in a manner that indicates that the light pulses accompanying the low temperature pulses arrived at phase points 1.5 h later than the actual phases at which they were given. We attribute this delay to a slowing down of the information that is apparently transmitted by a process that is temperature dependent.

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