共查询到20条相似文献，搜索用时 31 毫秒
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Miki Takao Chen-Goodspeed Misty Zhao Zhaoyang Lee Cheng Chi 《Journal of circadian rhythms》2013,11(1):1-2
Although out-of-lab investigation of the human circadian clock at the clock gene expression level remains difficult, a recent method using hair follicle cells might be useful. While exercise may function as an entrainment cue for circadian rhythms, it remains unclear whether exercise affects human circadian clock gene expression. Efforts to observe apparent effects of exercise on clock gene expression require that several specific conditions be met: intense exercise should be habitually performed at a relatively uncommon time of day over an extended period; and any relative phase shift thereby observed should be validated by comparison of exercise and no-exercise periods. Wake-up and meal times should be kept almost constant over the experimental period. The present study was conducted using a professional fighter who met these strict criteria as subject. Facial hair samples were collected at 4-h intervals around the clock to ascertain rhythms of clock gene expression. During a period in which nighttime training (from 20:00 to 22:00) was habitually performed, circadian clock gene expression was phase-delayed by 2 to 4 h compared with that during a no-exercise period. Maximum level and circadian amplitude of clock gene expression were not affected by the nighttime training. Our trial observations illustrate the possibility that heavy physical exercise might strongly affect the circadian phase of clock gene expression. Exercise might be therefore effective for the clinical care of circadian disorders. The results also suggest that athletes may require careful scheduling of heavy physical exercise to maintain normal circadian phase and ensure optimal athletic performance. 相似文献
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A number of recent studies have debated the existence and nature of clocks outside the suprachiasmatic nucleus that may underlie
circadian rhythms in conditions of food entrainment or methamphetamine administration. These papers claim that either the
canonical clock genes, or the circuitry in the dorsomedial nucleus of the hypothalamus, may not be necessary for these forms
of entrainment. In this paper, we review the evidence necessary to make these claims. In particular, we point out that it
is necessary to remove classical conditioning stimuli and interval timer (homeostatic) effects to insure that the remaining
entrainment is due to a circadian oscillator. None of these studies appears to meet these criteria for demonstrating circadian
entrainment under these conditions. Our own studies, which were discussed in detail by a recent Review in these pages by Mistlberger
and colleagues, came to an opposite conclusion. However, our studies were designed to meet these criteria, and we believe
that these methodological differences explain why we find that canonical clock gene Bmal1 and the integrity of the dorsomedial nucleus are both required to produce true circadian entrainment under conditions of
restricted feeding. 相似文献
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Xiaojia Wang Yueqi Wang Haoyang Xin Yanyou Liu Yuhui Wang Hang Zheng Zhou Jiang Chaomin Wan Zhengrong Wang Jian M Ding 《Journal of circadian rhythms》2006,4(1):9-9
Every physiological function in the human body exhibits some form of circadian rhythmicity. Under pathological conditions,
however, circadian rhythmicity may be dusrupted. Patients infected with HIV or addicted to drugs of abuse often suffer from
sleep disorders and altered circadian rhythms. Early studies in Drosophila suggested that drug seeking behavior might be related to the expression of certain circadian clock genes. Our previous research
showed that conditioned place preference with morphine treatment was altered in mice lacking the Period-1 (mPer1) circadian clock gene. Thus, we sought to investigate whether morphine treatment could alter the expression of mPer1, especially in brain regions outside the SCN and in peripheral tissues. Our results using Western blot analysis showed that
the mPER1 immunoreactivity exhibited a strong circadian rhythm in the brains of the control (Con), morphine-dependent (MD),
and morphine-withdrawal (MW) mice. However, the phase of the circadian rhythm of mPER1 expression in the brains of MD mice
significantly differed from that of the Con mice (p < 0.05). In contrast to mPER1 expression in the brain, the circadian rhythm
of mPER1 immunoreactivity in the kidneys was abolished after morphine administration, whereas the Con mice maintained robust
circadian rhythmicity of mPER1 in the kidney. Therefore, the effect of morphine on the circadian clock gene mPer1 may vary among different organs, resulting in desynchronization of circadian function between the SCN and peripheral organs. 相似文献
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Circadian clocks are believed to have evolved in parallel with the geological history of the earth, and have since been fine-tuned
under selection pressures imposed by cyclic factors in the environment. These clocks regulate a wide variety of behavioral
and metabolic processes in many life forms. They enhance the fitness of organisms by improving their ability to efficiently
anticipate periodic events in their external environments, especially periodic changes in light, temperature and humidity.
Circadian clocks provide fitness advantage even to organisms living under constant conditions, such as those prevailing in
the depth of oceans or in subterranean caves, perhaps by coordinating several metabolic processes in the internal milieu.
Although the issue of adaptive significance of circadian rhythms has always remained central to circadian biology research,
it has never been subjected to systematic and rigorous empirical validation. A few studies carried out on free-living animals
under field conditions and simulated periodic and aperiodic conditions of the laboratory suggest that circadian rhythms are
of adaptive value to their owners. However, most of these studies suffer from a number of drawbacks such as lack of population-level
replication, lack of true controls and lack of adequate control on the genetic composition of the populations, which in many
ways limits the potential insights gained from the studies. The present review is an effort to critically discuss studies
that directly or indirectly touch upon the issue of adaptive significance of circadian rhythms and highlight some shortcomings
that should be avoided while designing future experiments. 相似文献
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Girardin Jean-Louis Ferdinand Zizi Douglas R Lazzaro Arthur H Wolintz 《Journal of circadian rhythms》2008,6(1):1-8
The absence of circadian zeitgebers in the social environment causes circadian misalignment, which is often associated with sleep disturbances. Circadian misalignment, defined as a mismatch between the sleep-wake cycle and the timing of the circadian system, can occur either because of inadequate exposure to the light-dark cycle, the most important synchronizer of the circadian system, or reduction in light transmission resulting from ophthalmic diseases (e.g., senile miosis, cataract, diabetic retinopathy, macular degeneration, retinitis pigmentosa, and glaucoma). We propose that glaucoma may be the primary ocular disease that directly compromises photic input to the circadian time-keeping system because of inherent ganglion cell death. Glaucomatous damage to the ganglion cell layer might be particularly harmful to melanopsin. According to histologic and circadian data, a subset of intrinsically photoresponsive retinal ganglion cells, expressing melanopsin and cryptochromes, entrain the endogenous circadian system via transduction of photic input to the thalamus, projecting either to the suprachiasmatic nucleus or the lateral geniculate nucleus. Glaucoma provides a unique opportunity to explore whether in fact light transmission to the circadian system is compromised as a result of ganglion cell loss. 相似文献
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Jens Joschinski Katharina Beer Charlotte Helfrich-F?rster Jochen Krauss 《Journal of insect science (Online)》2016,16(1)
Seasonal timing is assumed to involve the circadian clock, an endogenous mechanism to track time and measure day length. Some debate persists, however, and aphids were among the first organisms for which circadian clock involvement was questioned. Inferences about links to phenology are problematic, as the clock itself is little investigated in aphids. For instance, it is unknown whether aphids possess diurnal rhythms at all. Possibly, the close interaction with host plants prevents independent measurements of rhythmicity. We reared the pea aphid Acyrthosiphon pisum (Harris) on an artificial diet, and recorded survival, moulting, and honeydew excretion. Despite their plant-dependent life style, aphids were independently rhythmic under light–dark conditions. This first demonstration of diurnal aphid rhythms shows that aphids do not simply track the host plant’s rhythmicity. 相似文献
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Barbara A Murphy Jeffrey A Elliott Dawn R Sessions Mandi M Vick Erin L Kennedy Barry P Fitzgerald 《Journal of circadian rhythms》2007,5(1):5-9
Background
Rapid displacement across multiple time zones results in a conflict between the new cycle of light and dark and the previously entrained program of the internal circadian clock, a phenomenon known as jet lag. In humans, jet lag is often characterized by malaise, appetite loss, fatigue, disturbed sleep and performance deficit, the consequences of which are of particular concern to athletes hoping to perform optimally at an international destination. As a species renowned for its capacity for athletic performance, the consequences of jet lag are also relevant for the horse. However, the duration and severity of jet lag related circadian disruption is presently unknown in this species. We investigated the rates of re-entrainment of serum melatonin and core body temperature (BT) rhythms following an abrupt 6-h phase advance of the LD cycle in the horse. 相似文献12.
Background
Recent advances in sociogenomics allow for comparative analyses of molecular mechanisms regulating the development of social behavior. In eusocial insects, one key aspect of their sociality, the division of labor, has received the most attention. Age-related polyethism, a derived form of division of labor in ants and bees where colony tasks are allocated among distinct behavioral phenotypes, has traditionally been assumed to be a product of convergent evolution. Previous work has shown that the circadian clock is associated with the development of behavior and division of labor in honeybee societies. We cloned the ortholog of the clock gene, period, from a harvester ant (Pogonomyrmex occidentalis) and examined circadian rhythms and daily activity patterns in a species that represents an evolutionary origin of eusociality independent of the honeybee. 相似文献13.
Leandro P Casiraghi Diego O Croci Francoise Poirier Gabriel A Rabinovich Diego A Golombek 《Journal of circadian rhythms》2010,8(1):4
Background
Recent evidence suggests a two-way interaction between the immune and circadian systems. Circadian control of immune factors, as well as the effect of immunological variables on circadian rhythms, might be key elements in both physiological and pathological responses to the environment. Among these relevant factors, galectin-1 is a member of a family of evolutionarily-conserved glycan-binding proteins with both extracellular and intracellular effects, playing important roles in immune cell processes and inflammatory responses. Many of these actions have been studied through the use of mice with a null mutation in the galectin-1 (Lgals1) gene. To further analyze the role of endogenous galectin-1 in vivo, we aimed to characterize the circadian behavior of galectin-1 null (Lgals1 -/-) mice. 相似文献14.
Background
It is reported that the circadian rhythms of female mating activity differ among Drosophila species and are controlled by an endogenous circadian clock. Here, we found that the mating rhythm of D. ananassae differed from that of D. melanogaster. Moreover, to evaluate the effect of clock gene products on mating activities, we examined the mating activity of D. melanogaster timeless (tim 01) transgenic fly harboring heat-shock promotor driven-D. ananassae timeless (tim) gene (hs-AT tim 01). 相似文献15.
Background
The central circadian pacemaker is a remarkably robust regulator of daily rhythmic variations of cardiovascular, endocrine, and neural physiology. Environmental lighting conditions are powerful modulators of circadian rhythms, but regulation of circadian rhythms by disease states is less clear. Here, we examine the effect of ischemic stroke on circadian rhythms in rats using high-resolution pineal microdialysis. 相似文献16.
Background
The human body exhibits a variety of biological rhythms. There are patterns that correspond, among others, to the daily wake/sleep cycle, a yearly seasonal cycle and, in women, the menstrual cycle. Sine/cosine functions are often used to model biological patterns for continuous data, but this model is not appropriate for analysis of biological rhythms in failure time data. 相似文献17.
ABSTRACT: BACKGROUND: An endogenous circadian clock controls locomotor activity in common spiny mice (Acomys cahirinus). However, little is known about the effects of constant light (LL) on this activity or about the existence of an additional food entrainable clock. A series of experiments were performed to investigate the effects of LL and DD on tau and activity levels. METHODS: Spiny mice were housed individually and their running wheel activity monitored. One group of mice was exposed to LD, DD and several intensities of LL. Another group was exposed to a restricted feeding (RF) paradigm in light: dark (LD) during one hour before the L to D transition. Significance of rhythmicity was assessed using Lomb-Scargle periodograms. RESULTS: In LD all animals exhibited nocturnal activity rhythms that persisted in DD. When animals were exposed to RF (during L), all of these animals (n = 11) demonstrated significant food anticipatory activity as well as an increase in diurnal activity. This increase in diurnal activity persisted in 4/11 animals during subsequent ad libitum conditions. Under LL conditions, the locomotor rhythms of 2/11 animals appeared to entrain to RF. When animals were exposed to sequentially increasing LL intensities, rhythmicity persisted and, while activity decreased significantly, the free-running period was relatively unaffected. In addition, the period in LL was significantly longer than the period in DD. Exposure to LL also induced long-term changes (after-effects) on period and activity when animals were again exposed to DD. CONCLUSIONS: Overall these studies demonstrate clear and robust circadian rhythms of wheel-running in A. cahirinus. In addition, LL clearly inhibited activity in this species and induced after-effects. The results also confirm the presence of a food entrainable oscillator in this species. 相似文献
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茶多酚及儿茶素对前列腺癌细胞生长的抑制作用 总被引：13，自引：1，他引：12
前列腺癌是最常见的恶性肿瘤之一。茶多酚及其儿茶素单体对前列腺癌细胞具有明显的抑制和诱导凋亡作用 ,作用效果的 IC50 顺序为 88、97、112μM(EGCG>ECG>EGC) ,EC几乎没有作用 ,但含 EC的 TPS(茶多酚 )和不含 EC的 TPS存在差异 ,它们的 IC50 为 39μg/ m l和 4 3μg/ m l,且成剂量效应和时间效应关系。同时用荧光显微镜可以看到癌细胞的凋亡小体。 相似文献
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