Abstract：
:The retinohypothalamic tract (RHT), a monosynaptic retinal projection to the SCN, is the major path by which light entrains the circadian system to the external photoperiod. The circadian system of rodents effectively integrates or counts photons, and the magnitude of the rhythm phase response is proportional to the total energy of the photic stimulus. In the present studies, responsiveness to light and integrative capacity of the circadian system were tested in hamsters after reduction of retinal photoreceptor input by 50%. At CT 19, animals in constant darkness with or without unilateral retinal occlusion were exposed to 1 of 6 irradiances of 5-min white-light pulses ranging from 0.0011 to 70 microW/cm(2) or 5 white-light pulses of 0.6 microW/cm(2) with durations ranging from 0.25 to 150.0 min. Assessment of light-induced circadian rhythm phase response and Fos expression in the SCN by these animals revealed that a 50% reduction in input from photoreceptors stimulated directly with light caused a decrease in responsiveness to the longest duration and highest irradiance pulses presented. Despite this effect, both the magnitude of Fos induction in the SCN and phase-shift response remained directly proportional to the total energy in the photic stimuli. The results support the view that a reciprocal relationship between stimulus irradiance and duration persists despite the 50% reduction in retinal photoreceptor input. The mechanism of integration neither resides in the retina nor in the RHT.
journal_name
J Biol Rhythmsjournal_title
Journal of biological rhythmsauthors
Muscat L,Morin LPdoi
10.1177/0748730405280458subject
Has Abstractpub_date
2005-12-01 00:00:00pages
513-25issue
6eissn
0748-7304issn
1552-4531pii
20/6/513journal_volume
20pub_type
杂志文章abstract：:Although overt diurnal rhythms of behavior do not begin until well after birth, molecular studies suggest that the circadian clock may begin much earlier at a cellular level: mouse embryonic fibroblasts, for example, already possess robust clocks. By multiple criteria, we found no circadian clock present in mouse embr...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730410385281
更新日期：2010-12-01 00:00:00
abstract：:Mice with targeted gene disruption have provided important information about the molecular mechanisms of circadian clock function. A full understanding of the roles of circadian-relevant genes requires manipulation of their expression in a tissue-specific manner, ideally including manipulation with high efficiency wit...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730418757006
更新日期：2018-04-01 00:00:00
abstract：:The Drosophila clock relies on transcriptional feedback loops that generate daily oscillations of the clock gene expression at mRNA and protein levels. In the evening, the CLOCK (CLK) and CYCLE (CYC) basic helix-loop-helix (bHLH) PAS-domain transcription factors activate the expression of the period (per) and timeless...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730407313817
更新日期：2008-04-01 00:00:00
abstract：:An intricate transcription-translation feedback loop (TTFL) governs cellular circadian rhythms in mammals. Here, we report that the zinc finger transcription factor Krüppel-like factor 9 (KLF9) is regulated by this TTFL, it associates in chromatin at the core circadian clock and clock-output genes, and it acts to modu...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730420913205
更新日期：2020-06-01 00:00:00
abstract：:The synchronizing stimulus, its transduction site, and the afferent pathways responsible for feeding entrainment remain unknown. In fish, the role of the diet in the development of feeding anticipatory activity (FAA) is not well understood and fundamental questions on the mechanisms of feeding entrainment, such as the...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/074873040101600107
更新日期：2001-02-01 00:00:00
abstract：:Numerous studies have used the classic van der Pol oscillator, which contains a cubic nonlinearity, to model the effect of light on the human circadian pacemaker. Jewett and Kronauer demonstrated that Aschoff's rule could be incorporated into van der Pol type models and used a van der Pol type oscillator with higher o...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/074873099129000867
更新日期：1999-12-01 00:00:00
abstract：:The human circadian timing system has previously been shown to free run with a period slightly longer than 24 h in subjects living in the laboratory under conditions of forced desynchrony. In forced desynchrony, subjects are shielded from bright light and periodic time cues and are required to live on a day length out...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/074873099129000597
更新日期：1999-06-01 00:00:00
abstract：:An understanding of the retinal mechanisms in mammalian photoentrainment will greatly facilitate optimization of the wavelength, intensity, and duration of phototherapeutic treatments designed to phase shift endogenous biological rhythms. A small population of widely dispersed retinal ganglion cells projecting to the ...
journal_title：Journal of biological rhythms
pub_type： 杂志文章,评审
doi：10.1177/0748730403018003005
更新日期：2003-06-01 00:00:00
abstract：:While the rapid development of personal computers and high-throughput recording systems for circadian rhythms allow chronobiologists to produce huge amounts of data, the software to analyze them often lags behind. Here, we announce newly developed chronobiology software that is easy to use, compatible with many differ...
journal_title：Journal of biological rhythms
pub_type： 信件
doi：10.1177/0748730411414264
更新日期：2011-10-01 00:00:00
abstract：:In Drosophila melanogaster, disruption of night by even short light exposures results in degradation of the clock protein TIMELESS (TIM), leading to shifts in the fly molecular and behavioral rhythms. Several lines of evidence indicate that light entrainment of the brain clock involves the blue-light photoreceptor cry...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/074873040101600303
更新日期：2001-06-01 00:00:00
abstract：:The frequency demultiplication hypothesis (FDH) posits that circannual rhythms are generated from circadian cycles by frequency transformation to the lower-frequency rhythm. To test the FDH, we determined the periods of the circannual body mass and estrous cycles of golden-mantled ground squirrels with circadian locom...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/074873048600100402
更新日期：1986-01-01 00:00:00
abstract：:Abstract The cyanobacterial clock protein KaiC regulates the circadian cycle by exhibiting rhythms in transcription, translation, and phosphorylation. KaiC phosphorylation persists in circadian cycling even under transcription-less conditions and was reconstituted in vitro by incubating KaiC, KaiA, and KaiB. This pres...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730406291329
更新日期：2006-10-01 00:00:00
abstract：:The safety and efficacy of chemotherapeutics can vary as a function of the time of their delivery during the day. This study aimed to improve the treatment of glioblastoma (GBM), the most common brain cancer, by testing whether the efficacy of the DNA alkylator temozolomide (TMZ) varies with the time of its administra...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730417696788
更新日期：2017-04-01 00:00:00
abstract：:The circadian rhythm of eclosion activity and its pacemaker were analyzed in a series of latitudinal races of Drosophila auraria ranging from 34.2 degrees to 42.9 degrees N in Japan. The phase of the rhythm (psi EL) to the daily photoperiod (PP) changes as daylength is increased, and the slope of psi EL (PP) changes w...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：
更新日期：1989-07-01 00:00:00
abstract：:Among the scientific resources that Colin Pittendrigh passed on to his colleagues after his death in 1996 were two unpublished papers. These manuscripts, developed first in the mid-1960s and continually updated and refined through the late 1970s, centered on the development and experimental exploration of a model of c...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730417716685
更新日期：2017-08-01 00:00:00
abstract：:The large repertoire of circadian rhythms in diverse organisms depends on oscillating central clock genes, input pathways for entrainment, and output pathways for controlling rhythmic behaviors. Stress-activated p38 MAP Kinases (p38K), although sparsely investigated in this context, show circadian rhythmicity in mamma...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730414555183
更新日期：2014-12-01 00:00:00
abstract：:Crustaceans have frequently been used to study the neuroethology of both agonistic behavior and circadian rhythms, but whether their highly stereotyped and quantifiable agonistic activity is controlled by circadian pacemakers has, so far, not been investigated. Isolated marbled crayfish (Procambarus spec.) displayed r...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730408328933
更新日期：2009-02-01 00:00:00
abstract：:From the mathematical study of simple models for circadian rhythm, the authors identified a clear effect of saturation in the enzyme kinetics on the promotion or suppression of a sustained oscillation. In the models, a clock gene (per gene) is transcribed to produce mRNAs, which are translated to produce proteins in t...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730402238239
更新日期：2002-12-01 00:00:00
abstract：:The classical power spectrum, computed in the frequency domain, outranks traditionally used periodograms derived in the time domain (such as the chi2 periodogram) regarding the search for biological rhythms. Unfortunately, classical power spectral analysis is not possible with unequally spaced data (e.g., time series ...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/074873099129000984
更新日期：1999-12-01 00:00:00
abstract：:The mammalian circadian clock is known to be entrained by both a daily light-dark cycle and daily feeding cycle. However, the mechanisms of feeding-induced entrainment are not as fully understood as those of light entrainment. To elucidate the first step of entrainment of the liver clock, we identified the circadian c...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730411405958
更新日期：2011-06-01 00:00:00
abstract：:The pineal organ of the lizard Anolis carolinensis acts as a transducer of photoperiodic information, since light can affect the pineal melatonin rhythm (PMR). The synthesis and secretion of melatonin may be a major mechanism whereby a circadian pacemaker within the pineal can control circadian clocks located elsewher...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/074873048700200303
更新日期：1987-10-01 00:00:00
abstract：:Sleep disturbances are an all-too-familiar symptom of jet lag and a prime source of complaints for transmeridian travelers and flight crews alike. They are the result of a temporary loss of synchrony between an abruptly shifted sleep period, timed in accordance with the new local day-night cycle, and a gradually reent...
journal_title：Journal of biological rhythms
pub_type： 杂志文章,评审
doi：10.1177/074873049501000209
更新日期：1995-06-01 00:00:00
abstract：:African sleeping sickness is characterized by alterations in rhythmic functions. It is not known if the disease affects the expression of clock genes, which are the molecular basis for rhythm generation. We used a chronic rat model of experimental sleeping sickness, caused by the extracellular parasite Trypanosoma bru...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730409360963
更新日期：2010-04-01 00:00:00
abstract：:The adjustment of hamsters to advanced light-dark (LD) cycles can be greatly accelerated by scheduling a single 3-hr bout of extra activity in a novel running wheel, starting about 7 hr before the time when the animals become active in the preceding LD cycle. The present experiments were designed to provide stronger e...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/074873048900400305
更新日期：1989-10-01 00:00:00
abstract：:The mammalian circadian pacemaker is located in the suprachiasmatic nucleus (SCN). Various inputs modulate pacemaker phase, including the serotonergic (5HTergic) input from the midbrain raphe. 5HT phase-advances the SCN pacemaker when applied during mid subjective day. In vitro studies indicate that 5HT advances the m...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/074873002129002429
更新日期：2002-04-01 00:00:00
abstract：:In vertebrates, reproductive output often increases with age. Unlike older birds, first-year photoperiodic birds lack experience with the reproductively stimulatory effects of long day lengths (photostimulation). We examined whether age-related differences in annual reproductive development could be partially attribut...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730412468087
更新日期：2013-02-01 00:00:00
abstract：:Siberian hamsters are photoperiodic seasonally breeding rodents. To date, there has been no evidence that Siberian hamsters exhibit an annual rhythm in reproductive, thermoregulatory, molt, or body mass changes. However, given that the termination of their winter cycle is under endogenous control, the authors thought ...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/074873040001500206
更新日期：2000-04-01 00:00:00
abstract：:To determine if a circadian rhythm known to be functionally related to the reproductive axis varies on a circannual basis, we monitored the circadian secretion of melatonin at monthly intervals for 2 years in four ovariectomized, estradiol-implanted ewes held in a constant short-day photoperiod. Prior to the study, ew...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/074873049501000104
更新日期：1995-03-01 00:00:00
abstract：:Activity patterns are the product of interactions between an internal circadian clock and direct responses to photic and nonphotic features of the environment that are said to "mask" the influence of that clock. Evolutionary transitions between nocturnality and diurnality involve changes in mechanisms underlying both ...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730409351672
更新日期：2010-02-01 00:00:00
abstract：:Testicular growth was monitored in male ferrets subjected to one of the following photoperiodic treatments begun at weaning (8 weeks of age): 8 hr light/day (short days), 18 hr light/day (long days), or short days followed by transition to long days at either 10, 12, or 14 weeks of age. Mean ages to achieve adult test...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/074873049000500301
更新日期：1990-10-01 00:00:00
