Abstract:
:The annual cycle of reproductive function in starlings (Sturnus vulgaris) is driven by seasonal changes in daylength and consists of a 6-month period of photosensitivity, culminating in maximal gonadal development, followed by a 6-month period of photorefractoriness. If male starlings are held under a constant photoperiod of 12 hr of light per day (LD 12:12), some individuals show circannual rhythms of testicular size. Do these rhythms consist of alternating periods of photosensitivity and photorefractoriness, and does the response depend on whether daylength is increased or decreased to 12 hr? Castrated starlings were transferred from natural short days in January (LD 9.5:14.5) to LD 12:12. Plasma LH decreased and then remained low for 2.5 years. Most birds molted, some twice. Other castrated birds were transferred from long days in August (LD 16:8) to LD 12:12. Plasma LH increased and then remained high for 15 months. None of these birds molted. Young starlings were exposed to LD 12:12 throughout incubation and thereafter. Plasma LH remained low until birds were 13 months old. All of these birds molted. These results demonstrate, first, that castrated starlings show no evidence of alternating periods of photosensitivity and photorefractoriness under LD 12:12; and second, that LD 12:12 can be perceived as a long day or a short day depending on photoperiodic history, and that young birds with no experience of any other daylength perceive LD 12:12 as a long day.
journal_name
J Biol Rhythmsjournal_title
Journal of biological rhythmsauthors
Dawson A,McNaughton FJdoi
10.1177/074873049300800204subject
Has Abstractpub_date
1993-07-01 00:00:00pages
141-50issue
2eissn
0748-7304issn
1552-4531journal_volume
8pub_type
杂志文章abstract::Since the advent of techniques to investigate gene expression on a large scale, numerous circadian rhythms in mRNA amount have been reported. These rhythms generally differ in amplitude and phase. The authors investigated how far a parameter not regulated by the circadian clock can influence the phase of a rhythm in R...
journal_title:Journal of biological rhythms
pub_type: 杂志文章
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abstract::Despite the omnipresence of artificial and natural light exposure, there exists little guidance in the United States and elsewhere on light exposure in terms of timing, intensity, spectrum, and other light characteristics known to affect human health, performance, and well-being; in parallel, there is little informati...
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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...
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journal_title:Journal of biological rhythms
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journal_title:Journal of biological rhythms
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journal_title:Journal of biological rhythms
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abstract::We investigated the extent to which photoperiodic fluctuations synchronize annual thyroid and gonadal rhythmicity in edible dormice. The effects of different daylength manipulations (LD 4:20, LD 6:18, LD 18:6, LD 20:4) were examined during the two critical ascending and regressive phases of the annual plasma testoster...
journal_title:Journal of biological rhythms
pub_type: 杂志文章
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更新日期:1991-01-01 00:00:00
abstract::The circadian clock controls 24-h biological rhythms in our body, influencing many time-related activities such as sleep and wake. The simplest circadian clock is found in cyanobacteria, with the proteins KaiA, KaiB, and KaiC generating a self-sustained circadian oscillation of KaiC phosphorylation and dephosphorylati...
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abstract::A recent report that popliteal illumination shifted the circadian rhythms of body temperature and melatonin challenged the longstanding belief that light phase-shifting the circadian system in mammals is mediated only through the retina. The authors tested effects of popliteal illumination and illumination provided th...
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abstract::Odors elicit a number of behavioral responses, including attraction and repulsion in Drosophila. In this study, the authors used a T-maze apparatus to show that wild-type Drosophila melanogaster exhibit a robust circadian rhythm in the olfactory attractive and repulsive responses. These responses were lower during the...
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abstract::The purpose of this study was to determine whether decreased day lengths affect reproduction or the immune system in inbred mice. Irrespective of a nocturnal pineal melatonin rise, the signal for day length information, body and testis weights were the same in various strains 8 weeks after transfer from long to short ...
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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...
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abstract::Honey bee (Apis mellifera) workers emerge from the pupae with no circadian rhythms in behavior or brain clock gene expression but show strong rhythms later in life. This postembryonic development of circadian rhythms is reminiscent of that of infants of humans and other primates but contrasts with most insects, which ...
journal_title:Journal of biological rhythms
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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...
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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
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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
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更新日期:1986-01-01 00:00:00
abstract::Endogenous circadian rhythms are involved in various photoperiodic responses of birds. Investigations involving the mechanisms of photoperiodic time measurement in birds have been confined mainly to temperate zone species using males exclusively. Due to the paucity of experimental evidence on subtropical birds that ha...
journal_title:Journal of biological rhythms
pub_type: 杂志文章
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更新日期:1995-12-01 00:00:00
abstract::Almost exclusively, photoperiodic insects respond to a given photoperiod in one of two ways: a "long-day" response or a "short-day" response. Intermediate responses occur only at a very restricted range of photoperiods (often less than 30 min) and are generally population phenomena rather than intermediate responses o...
journal_title:Journal of biological rhythms
pub_type: 杂志文章
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更新日期:1993-04-01 00:00:00
abstract::The authors have shown previously that vasopressin (VP) release from suprachiasmatic nucleus (SCN) efferents in rats is important for the timing of the circadian activity of the hypothalamo-pituitary-adrenal (HPA) axis, resulting in a circadian rise in corticosterone at dusk. When meals are supplied at a fixed time du...
journal_title:Journal of biological rhythms
pub_type: 杂志文章
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更新日期:1998-02-01 00:00:00
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journal_title:Journal of biological rhythms
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abstract::In our attempts to understand the circadian system, we unavoidably rely on abstractions. Instead of describing the behavior of the circadian system in all its complexity, we try to derive basic features from which we form a global concept on how the system works. Such a basic concept is a model of reality. The author ...
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journal_title:Journal of biological rhythms
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更新日期:1993-01-01 00:00:00
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