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, ewes had been housed in a short-day (8L:16D) photoperiod for 4 years and were exhibiting circannual reproductive rhythms as assessed by serum luteinizing hormone (LH) levels. Three of the four sheep showed unambiguous deviations from the expected nocturnal melatonin secretion at two different times approximately 1 year apart. Nocturnal rises in melatonin, which usually last the duration of the dark phase, were delayed by 3-14 h or were missing. Altogether, five of the seven melatonin alterations observed in these three ewes occurred during the nadir of the circannual LH cycle. In the remaining ewe, we did not observe an altered melatonin secretory pattern during this period, and this ewe also failed to show a high amplitude circannual cycle of LH. The results provide evidence for a circannual change in the circadian rhythm of melatonin secretion. This alteration in melatonin secretion may serve as a "functional" change in daylength, and thereby may influence the expression of the circannual reproductive rhythm of sheep held in a fixed photoperiod for an extended time.
journal_name
J Biol Rhythmsjournal_title
Journal of biological rhythmsauthors
Thrun LA,Moenter SM,O'Callaghan D,Woodfill CJ,Karsch FJdoi
10.1177/074873049501000104subject
Has Abstractpub_date
1995-03-01 00:00:00pages
42-54issue
1eissn
0748-7304issn
1552-4531journal_volume
10pub_type
杂志文章abstract：:Siberian hamsters (Phodopus sungorus) exhibit changes in immune function following adaptation to short photoperiods, including a marked attenuation of energetically expensive thermoregulatory and behavioral responses to gram-negative bacterial infections. Whether this seasonal attenuation of the immune response is idi...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730407311518
更新日期：2008-02-01 00:00:00
abstract：:The possibility that feeding may act as a zeitgeber has been investigated in captive Svalbard ptarmigan by recording feeding or food-searching activity (FA) in birds given periodic access to food (PAF) under light-dark (LD) cycles or in continuous bright (LL) or dim light (DD) conditions. Except during LL, anticipator...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/074873049801300504
更新日期：1998-10-01 00:00:00
abstract：:The mammalian SCN contains a biological clock that drives remarkably precise circadian rhythms in vivo and in vitro. Recent advances have revealed molecular and cellular mechanisms required for the generation of these daily rhythms and their synchronization between SCN neurons and to the environmental light cycle. Thi...
journal_title：Journal of biological rhythms
pub_type： 杂志文章,评审
doi：10.1177/0748730404268786
更新日期：2004-10-01 00:00:00
abstract：:Transplantation of the fetal suprachiasmatic nucleus (SCN) in arrhythmic SCN-lesioned rats can reinstate circadian drinking rhythms in 40% to 50% of the cases. In the current article, it was investigated whether the failure in the other rats could be due to the absence of a circadian rhythm in the grafted SCN, using a...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/074873099129000416
更新日期：1999-02-01 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 SCN has long had organizational schemas imposed on it. In most, the SCN is dichotomized, with one region typically associated with the presence of vasopressin cells and the other associated with cells containing vasoactive intestinal polypeptide and certain afferent terminal fields. If assumed to be accurate, the ...
journal_title：Journal of biological rhythms
pub_type： 杂志文章,评审
doi：10.1177/0748730406296749
更新日期：2007-02-01 00:00:00
abstract：:Various aspects of mammalian endocrine physiology show a time-of-day variation with a period of 24 h, which represents an adaptation to the daily environmental fluctuations resulting from the rotation of the earth. These 24-h rhythms in hormone abundance and consequently hormone function may rely on rhythmic signals p...
journal_title：Journal of biological rhythms
pub_type： 杂志文章,评审
doi：10.1177/0748730415580881
更新日期：2015-08-01 00:00:00
abstract：:A single light episode during the first larval stage can set the phase of adult Drosophila activity rhythms, showing that a light-sensitive circadian clock is functional in larvae and is capable of keeping time throughout development. These behavioral data are supported by the finding that neurons expressing clock pro...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730403260621
更新日期：2004-02-01 00:00:00
abstract：:Aging alters numerous aspects of circadian biology, including the amplitude of rhythms generated by the suprachiasmatic nuclei (SCN) of the hypothalamus, the site of the central circadian pacemaker in mammals, and the response of the pacemaker to environmental stimuli such as light. Although previous studies have desc...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730403251802
更新日期：2003-04-01 00:00:00
abstract：:We examine theoretical models for circadian oscillations based on transcriptional regulation in Drosophila and Neurospora. For Drosophila, the molecular model is based on the negative feedback exerted on the expression of the per and tim genes by the complex formed between the PER and TIM proteins. For Neurospora, sim...
journal_title：Journal of biological rhythms
pub_type： 杂志文章,评审
doi：10.1177/074873099129000948
更新日期：1999-12-01 00:00:00
abstract：:There is little evidence for the involvement of microRNAs (miRs) in the regulation of circadian rhythms, despite the potential relevance of these elements in the posttranscriptional regulation of the clock machinery. The present work aimed to identify miRs targeting circadian genes through a predictive analysis of con...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730413476827
更新日期：2013-04-01 00:00:00
abstract：:Rhodopsin 7 ( Rh7), a new invertebrate Rhodopsin gene, was discovered in the genome of Drosophila melanogaster in 2000, but its function has remained elusive. We generated an Rh7 null mutant ( Rh70) by P element-mediated mutagenesis and found that an absence of Rh7 had significant effects on fly activity patterns duri...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730417721826
更新日期：2017-10-01 00:00:00
abstract：:Previous research has demonstrated a clear link between late chronotype and depression. The vulnerability factors underpinning this link, however, are unclear. Here the relationship between two specific emotion regulation strategies, cognitive reappraisal and expressive suppression, and chronotype was investigated usi...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730417709111
更新日期：2017-08-01 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：:Threads of evidence from recent experimentation in retinal morphology, neurochemistry, electrophysiology, and visual perception point toward rhythmic ocular processes that may be integral components of circadian entrainment in mammals. Components of retinal cell biology (rod outer-segment disk shedding, inner-segment ...
journal_title：Journal of biological rhythms
pub_type： 杂志文章,评审
doi：10.1177/074873049100600104
更新日期：1991-04-01 00:00:00
abstract：:Female Drosophila melanogaster, like many other organisms, exhibit different behavioral repertoires after mating with a male. These postmating responses (PMRs) include increased egg production and laying, increased rejection behavior (avoiding further male advances), decreased longevity, altered gustation and decrease...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730416668048
更新日期：2016-12-01 00:00:00
abstract：:The suprachiasmatic nucleus (SCN) drives circadian rhythms in locomotion through coupled, single-cell oscillations. Global genetic deletion of the neuropeptide Vip or its receptor Vipr2 results in profound deficits in daily synchrony among SCN cells and daily rhythms in locomotor behavior and glucocorticoid secretion....
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730420932073
更新日期：2020-10-01 00:00:00
abstract：:Circadian clocks drive daily rhythms of physiology and behavior in multiple organisms and synchronize these rhythms to environmental cycles of light and temperature. The basic mechanism of the clock consists of a transcription-translation feedback loop, in which key clock proteins negatively regulate their own transcr...
journal_title：Journal of biological rhythms
pub_type： 杂志文章,评审
doi：10.1177/0748730419868136
更新日期：2019-12-01 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：:Using quantitative autoradiography, 2-(125)I-melatonin binding was investigated throughout the light:dark cycle in the suprachiasmatic nuclei (SCN), paraventricular nuclei (PVT), and pars tuberalis (PT) of adult female Siberian hamsters kept for 10 weeks in either long or short photoperiods (LP or SP, respectively). P...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/074873049601100406
更新日期：1996-12-01 00:00:00
abstract：:Reduced sensitivity to short-wavelength (blue) light with age has been shown for light-induced melatonin suppression. The current research aimed to determine if a similar age-related reduction occurs in subjective alertness, mood, and circadian phase-advancing responses. Young (n = 11, 23.0 +/- 2.9 years) and older (n...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730408328973
更新日期：2009-02-01 00:00:00
abstract：:The circadian pacemaker of the SCN is a heterogeneous structure containing many single-cell oscillators that display phase differences in gene expression and electrical activity rhythms. Thus far, it is unknown how single neurons contribute to the population signal measured from the SCN. The authors used single-unit e...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730406290317
更新日期：2006-08-01 00:00:00
abstract：:How the cellular elements of the SCN are synchronized to each other is not well understood. We explore circadian oscillations manifest at the level of the cell, the tissue, and the whole animal to better understand intra-SCN synchrony and master clock function of the nucleus. At each level of analysis, responses to va...
journal_title：Journal of biological rhythms
pub_type： 杂志文章,评审
doi：10.1177/0748730409344800
更新日期：2009-10-01 00:00:00
abstract：:On the southern Iberian Peninsula, the seasonal life history of the large white butterfly, Pieris brassicae, comprises 2 different photoperiodically induced developmental arrests: a hibernation diapause at photophases < 11 h and an estivation diapause at photophases > 14 h. At intermediate photophases (12 h to 13 h), ...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730404270388
更新日期：2004-12-01 00:00:00
abstract：:The role of the intergeniculate leaflet of the thalamus (IGL) in photoperiod responsiveness was examined in a laboratory-selected line of photoperiod nonresponsive (NR) Siberian hamsters. NR hamsters fail to exhibit typical winter-type responses (i.e., gonadal regression and development of winter-type pelage) when exp...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730406287996
更新日期：2006-06-01 00:00:00
abstract：:Melatonin is secreted systemically from the pineal gland maximally at night but is also produced locally in many tissues. Its chronobiological function is mainly exerted by pineal melatonin. It is a feedback regulator of the main circadian pacemaker in the hypothalamic suprachiasmatic nuclei and of many peripheral osc...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730415616678
更新日期：2016-02-01 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：:During the first 7 weeks of postnatal life, short day lengths inhibit the onset of puberty in many photoperiodic rodents, but not in Syrian hamsters. In this species, timing of puberty and fecundity are independent of the early postnatal photoperiod. Gestational day length affects postnatal reproductive development in...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730408322985
更新日期：2008-10-01 00:00:00
abstract：:The mammalian endogenous circadian clock, the suprachiasmatic nuclei, receives environmental inputs, namely the light-dark cycle, through photopigments located in the eye and from melanopsin-expressing retinal ganglion cells. The authors investigated the influence of light wavelength and intensity on the synchronizati...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730410368244
更新日期：2010-06-01 00:00:00
abstract：:The circadian clock represents an anticipatory mechanism, well preserved in evolution. It has a critical impact on most aspects of the physiology of light-sensitive organisms. These rhythmic processes are governed by environmental cues (fluctuations in light intensity and temperature), an internal circadian timing sys...
journal_title：Journal of biological rhythms
pub_type： 杂志文章,评审
doi：10.1177/0748730414557634
更新日期：2015-04-01 00:00:00
