The relationship between the golden spiny mouse circadian system and its diurnal activity: an experimental field enclosures and laboratory study

Examples of animals that switch activity times between nocturnality and diurnality in nature are relatively infrequent. Furthermore, the mechanism for switching activity time is not clear: does a complete inversion of the circadian system occur in conjunction with activity pattern? Are there switching centers downstream from the internal clock that interpret the clock differently? Or does the switch reflect a masking effect? Answering these key questions may shed light on the mechanisms regulating activity patterns and their evolution. The golden spiny mouse (Acomys russatus) can switch between nocturnal and diurnal activity. This study investigated the relationship between its internal circadian clock and its diurnal activity pattern observed in the field. The goal is to understand the mechanisms underlying species rhythm shifts in order to gain insight into the evolution of activity patterns. All golden spiny mice had opposite activity patterns in the field than those under controlled continuous dark conditions in the laboratory. Activity and body temperature patterns in the field were diurnal, while in the laboratory all individuals immediately showed a free-running rhythm starting with a nocturnal pattern. No phase transients were found toward the preferred nocturnal activity pattern, as would be expected in the case of true entrainment. Moreover, the fact that the free-running activity patterns began from the individuals' subjective night suggests that golden spiny mice are nocturnal and that their diurnality in their natural habitat in the field results from a change that is downstream to the internal clock or reflects a masking effect.     

Variations in circadian genes and individual nocturnal symptoms of insomnia. The HUNT study

Insomnia is a condition characterized by three nocturnal symptoms: problems with sleep onset or maintenance and early morning awakenings (terminal insomnia). Affected individuals may present one or more of these symptoms. Several studies have shown that insomnia is moderately heritable and that proxy phenotypes for the three insomnia symptoms show different heritabilities. This suggests that different nocturnal symptoms of insomnia may arise from different genetic and biological backgrounds. Circadian genes are good candidates to account for these differences as they regulate the periodicity of several physiological functions including sleep. Evidence from studies in animals and humans have suggested that circadian genes might be involved in sleep disturbances such as insomnia. In this study, we investigated the association between Single Nucleotide Polymorphisms (SNPs) in circadian genes and individual symptoms of insomnia and their combinations using data from the Nord-Trøndelag Health Study 3 (the HUNT3 study, N = 50807). Participants (N = 6029) provided information about sleep onset insomnia, maintenance insomnia, and terminal insomnia. Participants who responded “several times a week” to at least one question regarding the mentioned symptoms were classified as cases (N = 3577) and categorized in seven subgroups according to possible symptom combinations. Controls (N = 2452) answered “Never/Seldom” to all sleep-related questions. Using multinomial regression, we assessed 73 SNPs in nine circadian genes (PER1, 2, 3, CRY1, 2, TIMELESS, CLOCK, REV-ERBα, ARNTL) for differences among symptoms subgroups. Twenty-five SNPs showed significant p-values and supportive odds-ratios. All significant SNPs in PER3 were associated with reporting all three symptoms simultaneously. SNPs in CRY genes were associated with terminal insomnia alone or in combination with other symptoms. Genes PER1 and two were mostly associated with sleep maintenance insomnia. However, none of the SNPs remained significant after False Discovery Rate (FDR) correction for multiple statistical testing. In conclusion, even though none of the SNPs remained significant after FDR correction, the clustering of some genes around specific symptoms points to the need for additional research on these relationships.     

Clock polymorphisms and circadian rhythms phenotypes in a sample of the Brazilian population

A Clock polymorphism T to C situated in the 3' untranslated region (3'-UTR) has been associated with human diurnal preference. At first, Clock 3111C had been reported as a marker for evening preference. However these data are controversial, and data both corroborating and denying them have been reported. This study hypothesizes that differences in Clock genotypes could be observed if extreme morning-type subjects were compared with extreme evening-type subjects, and the T3111C and T257G polymorphisms were studied. The possible relationship between both polymorphisms and delayed sleep phase syndrome (DSPS) was also investigated. An interesting and almost complete linkage disequilibrium between the polymorphisms T257G in the 5' UTR region and the T3111C in the 3' UTR region of the Clock gene is described. Almost always, a G in position 257 corresponds to a C in position 3111, and a T in position 257 corresponds to a T in position 3111. The possibility of an interaction of these two regions in the Clock messenger RNA structure that could affect gene expression was analyzed using computer software. The analyses did not reveal an interaction between those two regions, and it is unlikely that this full allele correspondence affects Clock gene expression. These results show that there is no association between either polymorphism T3111C or T257G in the Clock gene with diurnal preference or delayed sleep phase syndrome (DSPS). These controversial data could result from the possible effects of latitude and clock genes interaction on circadian phenotypes.     

Clocks for the city: circadian differences between forest and city songbirds

To keep pace with progressing urbanization organisms must cope with extensive habitat change. Anthropogenic light and noise have modified differences between day and night, and may thereby interfere with circadian clocks. Urbanized species, such as birds, are known to advance their activity to early morning and night hours. We hypothesized that such modified activity patterns are reflected by properties of the endogenous circadian clock. Using automatic radio-telemetry, we tested this idea by comparing activity patterns of free-living forest and city European blackbirds (Turdus merula). We then recaptured the same individuals and recorded their activity under constant conditions. City birds started their activity earlier and had faster but less robust circadian oscillation of locomotor activity than forest conspecifics. Circadian period length predicted start of activity in the field, and this relationship was mainly explained by fast-paced and early-rising city birds. Although based on only two populations, our findings point to links between city life, chronotype and circadian phenotype in songbirds, and potentially in other organisms that colonize urban habitats, and highlight that urban environments can significantly modify biologically important rhythms in wild organisms.     

Differences in toxicity and outcome associated with circadian variations between patients undergoing daytime and evening radiotherapy for prostate adenocarcinoma

This retrospective study tested the hypothesis that disease control and treatment-related toxicity in patients undergoing high-dose radiotherapy (HDRT) for prostate cancer varies in a circadian manner. Patients with localized prostate adenocarcinoma receiving HDRT (median 78 Gy) to the prostate and involved seminal vesicle(s) without elective pelvic irradiation were divided into a daytime treatment (before 5 PM) group (n = 267) and evening treatment (after 5 PM) group (n = 142). Biochemical failure (Phoenix definition), acute and late gastrointestinal (GI) and genitourinary toxicities (Common Terminology Criteria for Adverse Events version 4), biochemical failure-free survival (BFFS) and freedom from late toxicity were assessed. Analyses were performed by binary logistic regression and Cox proportional hazard regression. The median follow-up was 68 months, and 75% of patients were ≥70 years old. Evening HDRT was significantly associated with worse freedom from ≥grade 2 late GI complications (hazard ratio = 2.96; p < 0.001). The detrimental effect of evening HDRT was significant in patients older than 70 years old (p < 0.001) but not in younger patients (p = 0.63). In a subgroup of propensity score-matched cohort with T2b–T3 disease (n = 154), the 5-year BFFS was worse in the evening group than the daytime group (72% vs. 85%, hazard ratio = 1.95, p = 0.05). Our study indicates that evening HDRT may lead to more GI complications, especially in older patients, and worse BFFS in patients with T2b–T3 disease.     

广东湛江保护区红树林种群的生物量及其分布格局

本文研究了广东湛江红树林自然保护区高桥镇红寨村及德耀村海滩红树植物的种群分布格局与生物量。结果表明：５年生桐花树群落、白骨壤群落、秋茄群落、１０年生木榄群落、３０年生红海榄群落的总生物量分别为５５４７５ｇ／ｍ２、１６３７０１ｇ／ｍ２、６２６４４８ｇ／ｍ２、４１３８４３ｇ／ｍ２、９６１０２０ｇ／ｍ２;其中地下部分生物量占总生物量的比例依次为３２２８％、４５４５％、４１３１％、２９８５％和２８２９％。计算得Ｓｈａｎｎｏｎ－Ｗｉｅｎｅｒ物种多样性指数为２２３２。种群的分布格局中桐花树、白骨壤、红海榄和秋茄种群为集群分布,而木榄种群为随机分布。     

小兴安岭天然针阔混交林主要树种空间格局及其关联性

在小兴安岭天然针阔混交林1.1 hm~2的固定样地内,本文调查和统计了其物种组成和林分径级结构。运用空间点格局分析方法中的O-ring函数,对种群的空间分布格局及其关联性进行分析。结果表明:样地内共有乔木树种15种,重要值排在前四位的依次为红皮云杉(Picea koraiensis)、枫桦(Betula costata)、春榆(Ulmus davidiana)和色木槭(Acer mono),红皮云杉和枫桦属于样地内的优势种,重要值分别为15.81%和11.10%。林下更新状态良好,枫桦的径级结构有呈正态分布的趋势,其余三种均呈现倒"J"形。O-ring函数结果证实,四个主要树种的种群空间分布格局相似,均在0—5 m小尺度上呈聚集分布,随着尺度的增大,逐渐变为随机分布;红皮云杉与其他三个主要种群之间在较大尺度上均呈现显著正相关或无相关,在小尺度上仅与枫桦呈极显著正相关;色木槭在较小尺度上与其他三个种群呈弱负相关性,随着尺度的增大,逐渐变为无相关性。     

An observational study on disturbed peripheral circadian rhythms in hemodialysis patients

The quality of life of hemodialysis (HD) patients is hampered by reduced nocturnal sleep quality and excessive daytime sleepiness. In addition to the sleep/wake cycle, levels of circadian biomarkers (e.g. melatonin) are disturbed in end-stage renal disease (ESRD). This suggests impaired circadian clock performance in HD patients, but the underlying mechanism is unknown. In this observational study, diurnal rhythms of sleep, serum melatonin and cortisol concentrations and clock gene mRNA expression are compared between HD patients (n?=?9) and healthy control subjects (n?=?9). In addition, the presence of circulating factors that might affect circadian rhythmicity is tested in vitro with cell culture experiments. Reduced sleep quality (median sleep onset latency [interquartile range] of 23.9 [17.3]?min for patients versus 5.0 [10] minutes for controls, p?<?0.01; mean (± SD) sleep efficiency 70.2?±?8.1% versus 82.9?±?10.9%, p?=?0.02 and mean awake minutes after sleep onset 104.8?±?27.9 versus 54.6?±?41.6 minutes, p?= 0.01) and increased daytime sleepiness (mean Epworth Sleepiness Score of 10.0?±?4.8 versus 3.9?±?2.0, p?<?0.01) were confirmed in HD patients. Reduced nocturnal melatonin concentrations (1 AM: 98.1 [122.9] pmol/L versus 12.5 [44.2] pmol/L, p?= 0.019; 5 AM: 114.0 [131.6] pmol/L versus 11.8 [86.8] pmol/L, p?= 0.031) and affected circadian control of cortisol rhythm and circadian expression of the clock gene REV-ERBα were found. HD patient serum had a higher capacity to synchronize cells in vitro, suggesting an accumulated level of clock resetting compounds in HD patients. These compounds were not cleared by hemodialysis treatment or related to frequently used medications. In conclusion, the abovementioned results strongly suggest a disturbance in circadian timekeeping in peripheral tissues of HD patients. Accumulation of clock resetting compounds possibly contributes to this. Future studies are needed for a better mechanistic understanding of the interaction between renal failure and perturbation of the circadian clock.     

Effects of twilights on circadian entrainment patterns and reentrainment rates in squirrel monkeys

Entrainment patterns of the circadian rhythms of body temperature and locomotor activity were compared in 6 squirrel monkeys (Saimiri sciureus) exposed to daily illumination cycles with abrupt transitions between light and darkness (LD-rectangular) or with gradual dawn and dusk transitions simulating natural twilights at the equator (LD-twilight). Daytime light intensity was 500 lux, and the total amount of light emitted per day was the same in the two conditions. Mean daytime body temperature levels were stable in LD-rectangular but increased gradually in LD-twilight, reaching peak levels during the dusk twilight. Locomotor activity showed a similar pattern, but with an additional, secondary peak near the end of dawn. Activity duration was about 0.5 h longer in LD-twilight than in LD-rectangular, but the time of activity midpoint was similar in the two conditions. Reentrainment of the body temperature rhythm was faster following an 8-h advance of the LD cycle than following an 8-h delay, but did not differ significantly between the two LD conditions. These results provide no evidence that the inclusion of twilight transitions affected the strength of the LD Zeitgeber, and suggest that the observed differences in the daily patterns reflected direct effects of light intensity on locomotor activity and body temperature rather than an effect of twilights on circadian entrainment mechanisms.Abbreviation LD light-dark     

毛乌素沙地油蒿(Artemisia ordosica)种群空间格局对比

以空间自相关分析、半方差分析和九项轨迹方差分析等方法对比研究了毛乌素沙地优良固沙小灌木油蒿(Artemisia ordosica)在不同沙地条件下的小尺度种群格局.结果表明:在半固定沙地上油蒿种群的空间自相关性和空间异质性较强,同时斑块与斑块间隙的分化较为显著;在固定沙地上油蒿种群的空间自相关性和空间异质性较弱,同时斑块与斑块间隙的分化较轻微.半固定沙地油蒿种群的空间格局可能受控于地表风沙流,因为频繁而强烈的风沙流可以通过淘汰非聚集植株促使油蒿种群发生斑块分化.聚集斑块不仅是半固定沙地油蒿种群生存的重要形式,而且是半固定沙地油蒿种群继续发展的基础.在半固定沙地上油蒿种群的面积扩增很可能通过斑块边缘的连续性扩张过程实现.固定沙地油蒿种群缺乏斑块分化的现象可能与种群盖度高和种内竞争剧烈有关.研究结果对流沙治理具有指导意义,当把油蒿人工移栽到流动沙地时,如果将其配置为斑块与斑块间隙交替排列的格局,将有助于提高流沙固定和植被恢复重建的效率.     

“MOONSTROKE”: Lunar patterns of stroke occurrence combined with circadian and seasonal rhythmicity—A hospital based study

Both time of the day and season have been shown to have a significant effect on stroke incidence. In contrast, the role played by the moon has been little studied. We aimed to investigate the potential association of the lunar phase with the incidence of stroke subtypes [intracerebral hemorrhage (ICH), transient ischemic attack (TIA) and ischemic stroke (IS)], adjusted by circadian and seasonal variations. Consecutive stroke admissions to the Royal Melbourne Hospital (RMH) were analyzed from 2004–2011. Of 6252 patients, 4085 (65.3%) had confirmed dates and hour of the day. Of these, 632 (15.5%) had ICH, 658 (16.1%) presented with TIA and 2202 (53.9%) had IS. There were also 593 (14.5%) stroke mimics. We measured the association of stroke incidence with a particular lunar phase using an incidence rate ratio (IRR) with 95% confidence intervals (CI) using Poisson regression model (new moon set as reference). Compared with new moon phase, ICHs occurred significantly more during the first quarter (IRR, 1.55; 95%CI, 1.04 to 2.30; p?=?0.03). More TIAs were observed during the first quarter and full moon than in new moon (IRR, 1.69; 95%CI, 1.16 to 2.46; p?=?0.01; IRR, 1.52; 95%CI, 0.00 to 2.31; p?=?0.05; respectively). Both ICH and TIA occurrence slightly decreased as lunar illumination increased (IRR, 0.99; 95%CI, 0.99 to 1.00; p?=?0.01; IRR, 0.99; 95%CI, 0.99 to 1.00; p?=?0.04; respectively). No association was found between lunar phase or illumination and IS. All stroke subtypes were less likely to happen between 12AM and 6AM than the remaining 18 h of the day. IS occurrence was significantly higher during the spring than summer (IRR, 1.14; 95%CI, 1.02 to 1.28; p?=?0.03). For the patients older than 65 years, incidence of both ICH and IS was higher in spring than in summer (IRR, 1.33; 95%CI, 1.01 to 1.74; p?=?0.04; IRR, 1.22; 95%CI, 1.06 to 1.39; p?=?0.005; respectively). The lunar phase and illumination are associated with both ICH and TIA incidence. These findings should be tested on other stroke databases.     

Developmental manipulation of the circadian pacemaker in the cockroach: relationship between pacemaker period and response to light

Abstract Previous research has shown that fundamental properties of the circadian pacemaker that drives the rhythm of locomotor activity in the cockroach Leucophaea maderae L. are permanently altered by exposure of animals to 22 or 26 h light cycles during post-embryonic development (Barrett & Page, 1989; Page & Barrett, 1989). The present results document differences between animals exposed to either constant darkness (DD) or constant light (LL) during postembryonic development in the free-running period, the phase shifting response to light pulses, and the response to an LL to DD transition of the adult pacemaker. In addition, the changes in pacemaker period and in the phase shifting response that result from raising animals in several different lighting conditions are shown to be strongly correlated. The data suggest there is a developmentally labile interdependence between the period of the pacemaker and its sensitivity to light.     

后河自然保护区水丝梨群落优势种群结构与格局

应用立木大小级对后河自然保护区水丝梨群落中水丝梨和曼青冈两优势种群径级结构进行了对比分析,同时采用方差／均值比的t检验法、Morisita指数Iq的F检验法、丛生指数I、负二项式指数k、平均拥挤系数m^*和聚块性指数m^*／m判定并检验了两优势种群的分布格局,并按径级分样地进行了格局类型及强度的比较．结果表明,水丝梨种群Ⅳ级占绝对优势,分别达到79．4％(Q1)和87．4％(Q2),I、Ⅱ级极少甚至缺乏,更新困难,为衰退成熟型;曼青冈种群在两样地中均为I级>Ⅱ级>Ⅲ级>Ⅳ级>V级,为增长型．群落中两优势种群均呈集群分布;但按径级结构分析两优势种群的分布格局有所区别：随径级的增大,水丝梨种群由随机分布到集聚程度逐渐增强的集群分布,而曼青冈种群的集聚程度逐渐下降直至随机分布。     

Short sleep and late bedtimes are detrimental to educational learning and knowledge transfer: An investigation of individual differences in susceptibility

Good sleep hygiene practices, including consistent bedtimes and 7–9 h of sleep/night, are theorized to benefit educational learning. However, individuals differ in how much sleep they need, as well as in their chronotype preference. Therefore, some students may be more vulnerable to the cognitive effects of sleep loss, later bedtimes and nonpreferred times of learning than others. One prominent example is the debate regarding whether sleep loss and later bedtimes affect classroom learning more in female or male students. To inform this gender-and-sleep-loss debate, we developed a virtual college-level lecture to use in a controlled, laboratory setting. During Session 1, 78 undergraduate students were randomly assigned to take the lecture at 12:00 (noon condition) or 19:30 (evening condition). Then participants wore wristband actigraphy for 1 week to monitor average and intraindividual variability in sleep duration, bedtime and midpoint of sleep. During Session 2, participants completed a test at the same time of day as Session 1. The test included basic questions that were similar to trained concepts during the lecture (trained items) as well as integration questions that required application of learned concepts (knowledge-transfer items). Bayesian analyses supported the null hypothesis that time of learning did not affect test performance. Collapsed across time of testing, regression analyses showed that shorter sleep durations and later bedtimes explained 13% of the variance in test performance. Longer sleep durations and earlier bedtimes predicted better test performance primarily in females, younger students and morning-types. Interestingly, students with above-median fluid intelligence scores were resilient to short sleep and late bedtimes. Our findings indicate that both sleep and circadian factors should be addressed to optimize educational learning, particularly in the students who are most susceptible to sleep loss.     

肠道菌群昼夜节律与宿主生物节律相互作用的研究进展

为了适应地球昼夜更替对机体的影响,哺乳动物进化出了一套内在的适应性计时机制,由此形成了生物钟系统（circadian clock）。昼夜节律作为该系统中的重要部分可与机体的代谢过程同步变化[1]。肠道菌群作为与机体共生的生物群落,在肠道功能方面发挥着重要作用。对肠道菌群的昼夜节律性波动以及与宿主生物节律之间的相互作用进行研究有重要意义。本文将着重阐述肠道菌群昼夜节律与宿主生物节律的相互作用,以及这种相互作用对宿主代谢的影响。     

我国农村居民生活能源碳排放的时空特征分析

随着生活质量的提高,我国农村居民生活能源消费呈现大幅增长的趋势,成为碳排放增长的新源泉。估算了我国30个省区2001—2013年的农村居民生活能源碳排放,采用碳基尼系数、Arc GIS技术分析了中国省级尺度农村居民生活能源碳排放的时空特征,并利用STIRPAT模型辨明了农村居民生活能源碳排放的主要影响因素。结果表明:(1)2001—2013年农村居民直接生活能源碳排放量和间接生活能源碳排放量分别增长了7.65%、9.16%。(2)东部、中部、西部地区的碳基尼系数呈下降趋势,说明各区域农村居民人均生活能源碳排放量的区域差异总体均呈缩小趋势。(3)2001—2013年间,处于我国农村居民人均直接生活能源碳排放高水平地区的空间格局分布相对较为稳定,而对于人均间接生活能源碳排放来说,处于低水平地区的空间格局分布较为稳定。(4)农村人口规模、农民人均纯收入、农村居民生活消费支出、青壮年人口比重对农村居民生活能源碳排放量具有促进作用,而农村居民能源消费结构对其具有减缓作用,且北方农村居民生活能源碳排放量明显高于南方。(5)从环境Kuznets曲线假说出发,经济发展是促使我国农村居民生活能源碳排放Kuznets曲线存在拐点的重要因素。     

Different patterns of circadian oscillation in the suprachiasmatic nucleus of hamster,mouse, and rat

Although spontaneous neural firing in the mammalian suprachiasmatic nucleus is accepted to peak once during mid-subjective day, dual activity peaks have been reported in horizontal brain slices taken from hamsters. These two peaks were interpreted as new evidence for the theory of dual circadian oscillators and raised the expectation that such activity would be found in other circadian model systems. We examined hamster, mouse, and rat slices in both coronal and horizontal planes and found a second peak of activity only in hamster horizontal preparations. This raises interesting questions about the relative circadian physiology of these important experimental animals.Abbreviations CT circadian time - SCN suprachiasmatic nucleus P.W. Burgoon and P.T. Lindberg contributed equally to this work.     

Differences in nutritional status between rural and urban Yucatec Maya children: The importance of early life conditions

Early-life conditions shape childhood growth and are affected by urbanization and the nutritional transition. To investigate how early-life conditions (across the “first” and “second” 1000 days) are associated with rural and urban children's nutritional status, we analyzed anthropometric data from Maya children in Yucatan, Mexico. We collected weight, height and triceps skinfold measures, then computed body mass and fat mass indices (BMI/FMI), in a cross-sectional sample of 6-year-olds (urban n = 72, rural n = 66). Demographic, socioeconomic and early-life variables (birthweight/mode, rural/urban residence, household crowding) were collected by maternal interview. We statistically analyzed rural-urban differences in demographic, socioeconomic, early-life, and anthropometric variables, then created linear mixed models to evaluate associations between early-life variables and child anthropometric outcomes. Two-way interactions were tested between early-life variables and child sex, and between early-life variables and rural-urban residence. Results showed that rural children were shorter-statured, with lower overweight/obesity and cesarean delivery rates, compared to urban children. Household crowding was a negative predictor of anthropometric outcomes; the strongest effect was in boys and in urban children. Birthweight positively predicted anthropometric outcomes, especially weight/BMI. Birth mode was positively (not statistically) associated with any anthropometric outcome. Cesarean delivery was more common in boys than in girls, and predicted increased height in urban boys. In conclusion, urbanization and household crowding were the most powerful predictors of Maya 6-year-old anthropometry. The negative effects of crowding may disproportionately affect Maya boys versus girls and urban versus rural children. Early-life conditions shape Maya children's nutritional status both in the “first” and “second” 1000 days.