Abstract：
:Male rose-ringed parakeets (Psittacula krameri) were transferred to a long photoperiod (LP; LD 16:8) or a short photoperiod (SP; LD 8:16) for 45 or 90 days on four dates corresponding to the beginnings of different reproductive phases in an annual testicular cycle, and testicular responsiveness was evaluated by comparison with the testicular volume, weight, seminiferous tubular diameter, and germ cell profiles of birds in a natural photoperiod (NP). Exposure of birds to LP during the progressive phase (November) led to precocious maturation of testes after 45 days, but induced regression at 90 days. After showing retarded gametogenic functions at 45 days, parallel (November) SP birds exhibited an accelerated rate of germ cell formation at day 90. During the prebreeding phase (January), there were no remarkable differences in any features of testes among NP. LP, and SP birds at 45 days, but gonadal involution in LP parakeets and active spermatogenesis in SP birds occurred after 90 days. The testes did not show any response to LP or SP for 45 and 90 days when the birds were transferred to altered photoperiods during the breeding (March) and preparatory (June) phases, indicating that the parakeets were photorefractory for at least 6 months (March through September). The results also suggest that initiation and termination of seasonal gametogenic activity in parakeets are possibly functions of endogenous rhythmicity or extraphotoperiodic environmental factors. Duration of light may have certain influences on the attainment of annual peak in spermatogenesis, but in all probability the species has a low photoperiod threshold for induction of testicular growth.
journal_name
J Biol Rhythmsjournal_title
Journal of biological rhythmsauthors
Maitra SK,Dey Mdoi
10.1177/074873049200700102subject
Has Abstractpub_date
1992-04-01 00:00:00pages
13-25issue
1eissn
0748-7304issn
1552-4531journal_volume
7pub_type
杂志文章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：: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
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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：: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 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 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：: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：: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：: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...
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journal_title：Journal of biological rhythms
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更新日期：1988-04-01 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
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更新日期：2010-02-01 00:00:00
abstract：:Extracellular spike activity from three different types of visual interneurons found in the optic lobe of the giant cockroach Blaberus giganteus was recorded. The spike rate of all three types of neurons fluctuated in a circadian manner in constant darkness (DD). Two types, so-called "on" neurons (ON1 and ON2), respon...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/074873049300800404
更新日期：1993-01-01 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：:Most visual system functions, such as opsin gene expression, retinal neural transmission, light perception, and visual sensitivity, display robust day-night rhythms. The rhythms persist in constant lighting conditions, suggesting the involvement of endogenous circadian clocks. While the circadian pacemakers that contr...
journal_title：Journal of biological rhythms
pub_type： 杂志文章,评审
doi：10.1177/0748730419863917
更新日期：2019-10-01 00:00:00
abstract：:Sex differences in circadian rhythms have been reported with some conflicting results. The timing of sleep and length of time in bed have not been considered, however, in previous such studies. The current study has 3 major aims: (1) replicate previous studies in a large sample of young adults for sex differences in s...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730413511771
更新日期：2013-12-01 00:00:00
abstract：:Seasonal changes in numerous aspects of mammalian immune function arise as a result of the annual variation in environmental day length (photoperiod), but it is not known if absolute photoperiod or relative change in photoperiod drives these changes. This experiment tested the hypothesis that an individual's history o...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/0748730409349714
更新日期：2009-12-01 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：: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
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更新日期：1995-06-01 00:00:00
abstract：:Numerous studies have demonstrated sleep-promoting effects of melatonin treatment in humans, as evidenced by subjects' self-reports, polysomnographic recordings, and continuous actigraphic registration of motor activity. The sleep-promoting effects of either physiological or pharmacological doses of melatonin typicall...
journal_title：Journal of biological rhythms
pub_type： 杂志文章,评审
doi：10.1177/074873049701200620
更新日期：1997-12-01 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
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更新日期：2004-10-01 00:00:00
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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doi：10.1177/0748730412440851
更新日期：2012-06-01 00:00:00
abstract：:Circadian rhythms are programmed by the suprachiasmatic nucleus (SCN), which relies on neuropeptide signaling to maintain daily timekeeping. Vasoactive intestinal polypeptide (VIP) is critical for SCN function, but the precise role of VIP neurons in SCN circuits is not fully established. To interrogate their contribut...
journal_title：Journal of biological rhythms
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更新日期：2020-08-01 00:00:00
abstract：:Many mammalian cell types show daily rhythms in gene expression driven by a circadian pacemaker. For example, cultured astrocytes display circadian rhythms in Period1 and Period2 expression. It is not known, however, how or which intercellular factors synchronize and sustain rhythmicity in astrocytes. Because astrocyt...
journal_title：Journal of biological rhythms
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doi：10.1177/0748730409332042
更新日期：2009-04-01 00:00:00
abstract：:A 24-h treatment with the cytokine tumor necrosis factor-alpha (TNF-alpha) suppresses transcription of E-box-driven clock genes (D-site albumin promoter binding protein, Dbp; Tyrotroph embryonic factor, Tef ; Hepatic leukemia factor, Hlf; Period homolog to Drosophila 1/2/3, Per1, Per2, and Per3) by yet unknown molecul...
journal_title：Journal of biological rhythms
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更新日期：2009-08-01 00:00:00
abstract：:The circadian timing system has three principal elements: the retina, the intergeniculate leaflet (IGL) of the thalamus, and the suprachiasmatic nucleus (SCN). Since the human circadian timing system cannot be studied experimentally, we have used another primate, the macaque monkey, to help provide insight into the or...
journal_title：Journal of biological rhythms
pub_type： 杂志文章,评审
doi：
更新日期：1993-01-01 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：: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：: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：:Past research has shown that there is a circadian oscillator in laboratory rats that is entrained by restricted feeding schedules. However, in laboratory rats at least, the light-dark (LD) cycle is the dominant zeitgeber in the entrainment of wheel-running activity rhythms. Given that dasyurid marsupials are predomina...
journal_title：Journal of biological rhythms
pub_type： 杂志文章
doi：10.1177/074873048900400104
更新日期：1989-04-01 00:00:00
abstract：:The measurement of circulating levels of brain-derived neurotrophic factor (BDNF) has been proposed to be a marker of disease and an indicator of recovery. Thus, knowing the temporal pattern and influence of potential circadian rhythms is important. Although several studies have measured BDNF at different times of day...
journal_title：Journal of biological rhythms
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doi：10.1177/0748730417693124
更新日期：2017-02-01 00:00:00
