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Genetically encoded biological clocks are found broadly throughout life on Earth, where they generate circadian (about a day) rhythms that synchronize physiology and behavior with the daily light/dark cycle. Although the genetic networks that give rise to circadian timing are now fairly well established, our understanding of how the proteins that constitute the molecular ‘cogs’ of this biological clock regulate the intrinsic timing, or period, of circadian rhythms has lagged behind. New studies probing the biochemical and structural basis of clock protein function are beginning to reveal how assemblies of dedicated clock proteins form and evolve through post-translational regulation to generate circadian rhythms. This review will highlight some recent advances providing important insight into the molecular mechanisms of period control in mammalian clocks with an emphasis on structural analyses related to CK1-dependent control of PER stability.

Many organisms are subjected to a daily cycle of light and darkness, which significantly influences metabolic and physiological processes. In the present study, Neopyropia yezoensis, one of the major cultivated seaweeds used in "nori," was harvested in the morning and evening during light/dark treatments to investigate daily changes in gene expression using RNA-sequencing. A high abundance of transcripts in the morning includes the genes associated with carbon-nitrogen assimilations, polyunsaturated fatty acid, and starch synthesis. In contrast, the upregulation of a subset of the genes associated with the pentose phosphate pathway, cell cycle, and DNA replication at evening is necessary for the tight control of light-sensitive processes, such as DNA replication. Additionally, a high abundance of transcripts at dusk encoding asparaginase and glutamate dehydrogenase imply that regulation of asparagine catabolism and tricarboxylic acid cycle possibly contributes to supply nitrogen and carbon, respectively, for growth during the dark. In addition, genes encoding cryptochrome/photolyase family and histone modification proteins were identified as potential key players for regulating diurnal rhythmic genes.

We previously reported that brotizolam, but not suvorexant, delayed recovery from isoflurane anesthesia in mice. However, the effects of hypnotics may be altered by the circadian rhythm. Locomotor activity was measured using sighted (ICR and C57BL/6J) and blind (FVB/N and C3H/HeN) mice, and the effects of hypnotics on isoflurane anesthesia were compared during the light and dark periods. In sighted mice, recovery induced by brotizolam was delayed in the light period, while that by suvorexant was delayed in the dark period. In C57BL/6J mice, delayed recovery induced by brotizolam was marked, and that by suvorexant was observed in the light and dark periods. Locomotor activity was low in the last 6 h of the dark period in blind mice, and was similar to that in the light period. In blind mice, delayed recovery induced by brotizolam was identical in both periods, while suvorexant did not influence recovery from isoflurane anesthesia. These results suggest that the effects of hypnotics on isoflurane anesthesia are altered by the circadian rhythm and that daily light–dark stimuli may be required for the chronopharmacological effects of hypnotics.

Regeneration is an elegant and complex process informed by both local and long-range signals. Many current studies on regeneration are largely limited to investigations of local modulators within a canonical cohort of model organisms. Enhanced genetic tools increasingly enable precise temporal and spatial perturbations within these model regenerators, and these have primarily been applied to cells within the local injury site. Meanwhile, many aspects of broader spatial regulators of regeneration have not yet been examined with the same level of scrutiny. Recent studies have shed important insight into the significant effects of environmental cues and circulating factors on the regenerative process. These observations highlight that consideration of more systemic and possibly more broadly acting cues will also be critical to fully understand complex tissue regeneration. In this review, we explore the ways in which systemic cues and circulating factors affect the initiation of regeneration, the regenerative process, and its outcome. As this is a broad topic, we conceptually divide the factors based on their initial input as either external cues (for example, starvation and light/dark cycle) or internal cues (for example, hormones); however, all of these inputs ultimately lead to internal responses. We consider studies performed in a diverse set of organisms, including vertebrates and invertebrates. Through analysis of systemic mediators of regeneration, we argue that increased investigation of these “systemic factors” could reveal novel insights that may pave the way for a diverse set of therapeutic avenues.

The selection of unialgal culture strains suitable as sources of algal hemagglutinins is one of the important factors for success in algal component production. To obtain suitable unialgal culture strains, several Gracilariopsis chorda and Gracilaria vermiculophylla strains were surveyed for hemagglutinating activity, relative growth rates, and fertility difficulty. Fertile tetrasporophyte samples of naturally occurring G. chorda and G. vermiculophylla were collected at each of three different collection sites around Shikoku Island in southwest Japan. Unialgal culture strains were started from isolated tetraspores obtained from each naturally occurring plant. The hemagglutinating activities in algal extracts of the three G. chorda strains (3100–7000 units mg−1) were higher than those of the three G. vermiculophylla strains (920–980 units mg−1). The daily growth rates of the G. chorda strains (8.0–13.8% day−1 at 22 °C) were higher than those of the G. vermiculophylla strains (4.1–4.4% day−1 at 22 °C). Among the unialgal culture strains tested, the one started from isolated tetraspores from G. chorda growing in the Katsuura River had the highest hemagglutinating activity and relative growth rate. This strain also did not become fertile even after a period of 3 years of culture with aeration at 22 °C, in a 14-h light–10-h dark cycle at 60 μmol photons m−2 s−1. Thus, the unialgal culture strain started from isolated tetraspores from G. chorda growing in the Katsuura River seems to be a useful source for hemagglutinin production.

In aquaculture, it is necessary to determine of the diurnal biological variations in the intestines to determine an appropriate feeding schedule. The present study aimed to examine the transcriptomes of the

The purpose of this study was to investigate the effects of light exposure on farrowing performance in sows. Thirty sows were moved to the farrowing unit at d 110 of gestation and assigned a treatment: 12 h light/12 h dark cycle (Dark) or 24 h light (Light). Treatments began upon entry into the farrowing unit. Video was recorded continuously from initiation of the treatments until completion of farrowing. Data collected included duration of farrowing, birthing interval, and behavior during farrowing. Additionally, the number of total born, liveborn, and stillborn piglets was recorded. Gestation length was different between treatments, with a shorter gestation in Dark treatment sows than Light treatment sows (116.4 vs. 117.1 ± 0.2 d, respectively, p = 0.027). The total duration of parturition and number of liveborn did not differ (p = 0.393). Number of stillborn piglets between treatments did differ (p = 0.018). Dark had more stillborns compared to Light treatment sows (1.5 vs. 0.7 ± 0.2 piglets, respectively). Neither the interval between piglets nor farrowing behavior differed between treatments (p &gt, 0.100). The results from this experiment indicate that a sudden change in photoperiod has the potential to impact the gestation length of sows and number of stillborn pigs.

Stress is a complex phenomenon and exposure to stress results in a series of reactions in the organism, including alterations in behaviour and various physiological changes. Role of nutrition in the maintenance of homeostatic mechanisms, including the stress, is very dense. The current study aimed to evaluate the potential effects of Spirulina (Arthrospira) platensis against mix stress models. For this purpose, 36 Sprague-Dawley male rats were allocated into four groups; 1. Control(C), 2. Stress(S), 3. S.platensis (Sp) and 4. S. platensis + Stress (SpS). S. platensis was applied to Sp and SpS groups by oral gavage (1500 mg/kg/day) for 28 days. All rats were exposed to light : dark cycle (long lightening period; 18h light : 6h dark) stress for 14 days. Also, S and SpS groups were stressed with additional mix stress by leaving in crowded environment and hosting alone under long lightening period. The animals which fed with S. platensis, shown significant changes in the numbers of circulating leukocytes, % of neutrophils, and the neutrophil : lymphocyte ratio. However, there were no significant differences in the morphological parameters. In conclusion, the possible preventive effect of S. platensis on hematological parameters was shown in a rat’s stress model of social stress which was included mix stress under long lightening period.

Ozet Gecmis zamanlarda insanlar vakitlerinin cogunu dis ortamlarda ve gunes isigi altinda gecirmekteydi. Gunumuzde ise insanlar vakitlerinin cogunu ev, ofis, hastane, okul gibi kapali ortamlarda ve yapay aydinlatma kaynaklarinin olusturdugu isiklar altinda gecirmektedir. Gun isigi, gunesin konumundaki degisime gore gun icerisinde renk sicakligi, isik siddeti, isik rengi gibi parametrelerde degisim gosterdiginden dolayi dinamik yapilidir. Buna karsin yapay isik kaynaklari ile saglanan aydinlatma gun boyu sabittir. Insan sirkadiyen ritmi ve buna bagli biyolojik saati dunyanin aydinlik karanlik dongusu ile senkronizedir. Dolayisiyla kapali ortamlarda maruz kalinan aydinlatmaya bagli olarak insanlarin sirkadiyen ritimlerinin bozulmasindan kaynakli sorunlar olusabilir. Insanlarin yasam ve calisma alanlarina gunes isiginin dinamik atmosferinin tasinmasi ve biyolojik saat ile sirkadiyen ritimlerinin bozulmasinin onlenmesi amacindan “insan odakli aydinlatma” fikri dogmustur. Yapilan calismada insan odakli aydinlatma ve etkileri ele alinmistir. Abstract In the past, people have spent most of their time in an outdoors and in the sunlight. Nowadays, people spend most of their time in an indoors such as home, office, hospital, school and under the lights of artificial lighting sources. Daylight is dynamic due to changes in parameters such as color temperature, light intensity, light color during the day according to the change in the position of the sun. In contrast, lighting provided by artificial light sources is constant throughout the day. The human circadian rhythm and its associated biological clock are synchronized with the light dark cycle of the world. Therefore, depending on the lighting that is exposed in indoor environments, problems may arise due to the deterioration of the circadian rhythm of people. The idea of human centric lighting emerged in order to create a dynamic atmosphere of sunlight in people's life and working areas and to prevent the deterioration of the biological clock and circadian rhythms. In this study, human centric lighting and its effects are discussed.

The locomotor activity of the supralittoral Oniscidea species, Tylos europaeus collected from Barkoukech Beach was monitored in individual animals under natural light/dark cycle, constant darkness ...

The behavioral patterns of Mongolian gerbils (Meriones unguiculatus) housed individually and in same-sex groups (siblings) were characterized. Gerbils were continuously video-recorded 24 hours (day 1) and 120 hours (day 5) after housing conditions were established (no environmental enrichment was implemented). Video samples totaling 2016 minutes were scored to obtain measures of maintenance (drinking, sleeping, grooming, and eating), locomotor (jumping and rearing), communication (foot stomping), and stereotyped behaviors (gnawing bar and digging), which were compared across housing conditions and sex. Irrespective of sex or housing, gerbils dedicated between 65 and 75% of the day to maintenance behaviors; more than 50% of this time was dedicated to sleep. Time allocated to other behavioral states—for example, bar gnawing, digging, and eating—remained below 5% of the observation time. A comparison of day 1 and day 5 only indicated an increase in water consumption. Housing only affected water-drinking time during day 1, with individual gerbils spending more time drinking than grouped animals. Independent effects of sex were only observed for sleep and the overall behavioral category of maintenance during day 5. Further exploration of sleep patterning across different periods of the day was conducted. Distribution of sleeping was less systematic during day 1 than during day 5, most likely related to habituation to the new housing conditions. During day 5, regardless of sex or housing, gerbils showed the lowest levels of sleeping at the start of the dark cycle (18:00-20:59 hours) and the highest around midnight (00:00-02:59 hours). Although these findings require future replication with more robust groups of animals, they overall support the notion that captive gerbils are crepuscular—that is, more active during light-to-dark transitions—and suggest that changes in housing produce disruptions of activity-sleeping patterns and water consumption of adult gerbils.

Hospitalization in neonatal intensive care units predisposes preterm neonates to negative stimuli such as continuous 24-hourlighting. Potential benefits and harms of different lighting in neonatal units have not been quantified. Therefore, this study aimed to evaluate the benefits of a cycled lighting (light/dark cycle) in the Neonatal Intensive Care Unit on weight and cardiorespiratory function in premature infants. A Randomized Clinical Trial: Performed on preterm neonates who hospitalized in NICU at Assiut University Children Hospital, Egypt. From admission to discharge, neonates were randomly exposed to cyclical lighting (study) or continuous lighting (control) groups, twenty in each one. A structured questionnaire was used to collect data and included personal data, weight and cardiorespiratory assessment. The Results: Of the study revealed that mean of neonates weight in the study group was significantly greater than control group (P. 0.017). Mean pulse rates at 10 days and at discharge were significantly more stable in the study group compared to control group (p

In modern society, more and more people suffer from circadian disruption, which in turn affects health. But until now, there are no widely accepted therapies for circadian disorders. Rhythmic feeding behavior is one of the most potent non-photic zeitgebers, thus it has been suggested that it was important to eat during specific periods of time (time-restricted feeding, TRF) so that feeding is aligned with environmental cues under normal light/dark conditions. Here, we challenged mice with a 6 h advanced shift, combined with various approaches to TRF, and found that food restricted to the second half of the nights after the shift facilitated adaptation. This coincided with improved resilience to sepsis. These results raise the possibility of reducing the adverse responses to jet lag by subsequent timing of food intake.

Plant growth responses to cues such as light, temperature, and humidity enable the entrainment of the circadian rhythms with diurnal cycles. For example, the temperature variations between day and night affect plant growth and accompany the time lag to light cycle. Despite its importance, there has been no systematic investigation into time lags, and the mechanisms behind the entrainment of the circadian rhythms with multiple cycles remain unknown. Here, we investigated systemically the effects of the time lag on the circadian rhythm and growth in Arabidopsis thaliana. To investigate the entrainment status of the circadian clock, the rhythm of the clock gene CIRCADIAN CLOCK ASSOCIATION 1 (CCA1) was measured with a luciferase reporter assay. As a result, the rhythm was significantly modulated by the time lag with +10°C heating for 4 h every day but not −10°C cooling. A model based on coupled cellular oscillators successfully described these rhythm modulations. In addition, seedling growth depended on the time lag of the heating cycle but not that of the cooling cycle. Based on the relationship between the CCA1 rhythms and growth, we established an estimation method for the effects of the time lag. Our results found that plant growth relates to the CCA1 rhythm and provides a method by which to estimate the appropriate combination of light–dark and temperature cycles.

Refereed/Peer-reviewed Concepts in microplastics studies are not well established due to the emerging nature of microplastic research, especially in jellyfish. We conducted experiments to test whether ephyrae would ingest more microbeads via trophic transfer than direct ingestion and whether medusae would ingest more aged microbeads than virgin microbeads. We exposed ephyrae of Aurelia coerulea to two treatments, aged microbeads and Artemia nauplii that had ingested microbeads. We found that the ephyrae ingested 35 times more microbeads via trophic transfer than by direct ingestion. In the second experiment, medusae of A. coerulea were exposed to virgin microbeads and microbeads in seawater under a 12/12 light/dark cycle or constant darkness. Ingestion rates of microbeads from the light incubation were greater than those from the dark incubation or virgin microbeads, suggesting the likely presence of photosynthetic organisms in biofilms from the light incubation increased the palatability of the microbeads and promoted their ingestion.

espanolIntroduccion: la mayoria de los organismos que habitan este planeta tienen funciones ritmicas que siguen ciclos cercanos a las 24 horas, resultado de la adaptacion evolutiva. La alteracion de estos ritmos provoca disrupcion en funciones como el gasto y el consumo de energia, y el metabolismo de los lipidos y la glucosa, ademas de alterar varios parametros bioquimicos. Objetivo: el objetivo de este trabajo fue determinar el efecto de la alteracion del ciclo luz-oscuridad sobre el consumo diurno y nocturno de alimento y el peso corporal en ratas. Material y metodos: se llevaron a cabo tres experimentos con un grupo experimental y uno de control en cada uno de ellos. Los grupos estuvieron compuestos de seis machos de cuatro meses de edad cada uno. Cada experimento tuvo una duracion de 30 dias, comenzando con una linea base de 10 dias y realizando inversiones del ciclo luz-oscuridad durante los otros 20 dias. En el primer experimento se realizo una inversion al termino de la linea base; en el experimento dos se realizo en los dias 10 y 20; en el tercero, las inversiones se realizaron cada cinco dias, tras los 10 dias de la linea base. Resultados: los resultados muestran una ganancia de peso corporal menor en los grupos experimentales en relacion con los grupos de control. Conclusion: no se encontro ninguna diferencia significativa en el consumo de alimento total pero si en los patrones de consumo diurno y nocturno, que se intensificaron con el aumento de la frecuencia de la inversion del ciclo luz-oscuridad. EnglishBackground: most organisms inhabiting this planet have rhythmic functions in cycles that approximate 24 hours as a result of evolutionary adaptation. Disruption of these rhythms causes disruption in many bodily functions, including energy expenditure and consumption, and lipid and glucose metabolism, in addition to altering several biochemical parameters. Objective: the aim of this study was to determine the effect of altering the light-dark cycle on diurnal and nocturnal food consumption and body weight in rats. Material and methods: three experiments were carried out with an experimental group and a control group in each one. The groups included six males with an age of four months at the beginning of the experiment. Each experiment was 30 days long, starting with a baseline of 10 days and then inverting the light-dark cycle for another 20 days. In the first experiment the inversion took place at the end of the baseline period; in the second, the inversion was performed on days 10 and 20; in the third experiment inversions occurred every five days following the initial 10 days of baseline. Results: our results show a lower body weight gain in the experimental groups when compared to the control groups. Conclusions: significant differences in total consumption of food were not found, but were seen in the patterns of day and night consumption, along with a tendency to develop alterations characteristic of metabolic syndrome, which increased with the frequency of light-dark cycle inversion.

Cyanobacteria are photosynthetic organisms that are known to be responsible for oxygenating Earth’s early atmosphere. Having evolved to ensure optimal survival in the periodic light/dark cycle on this planet, their genetic codes are packed with various tools, including a sophisticated biological timekeeping system. Among the cyanobacteria is Synechococcus elongatus PCC 7942, the simplest clock-harboring organism with a powerful genetic tool that enabled the identification of its intricate timekeeping mechanism. The three central oscillator proteins—KaiA, KaiB, and KaiC—drive the 24 h cyclic gene expression rhythm of cyanobacteria, and the “ticking” of the oscillator can be reconstituted inside a test tube just by mixing the three recombinant proteins with ATP and Mg2+. Along with its biochemical resilience, the post-translational rhythm of the oscillation can be reset through sensing oxidized quinone, a metabolite that becomes abundant at the onset of darkness. In addition, the output components pick up the information from the central oscillator, tuning the physiological and behavioral patterns and enabling the organism to better cope with the cyclic environmental conditions. In this review, we highlight our understanding of the cyanobacterial circadian clock and discuss how it functions as a molecular chronometer that readies the host for predictable changes in its surroundings.

Background: Environmental disorders of the circadian rhythms can lead to metabolism-related diseases or exacerbate pathological conditions. Non-alcoholic fatty liver disease (NAFLD) has emerged with a growing occurrence. In the present study, we attempted to indicate whether circadian clock may influence lipid deposition and the expression levels of autophagy-related genes in liver of mice. Methods: High-fat diet and abnormal light/dark cycles were employed to induce a mouse model of NAFLD with circadian rhythm sleep disorder. Herein, liver samples were obtained at ZT0, ZT4, ZT8, ZT12, ZT16, and ZT20 time-point to detect the rhythmic expressions of circadian genes, autophagy-related genes, and Rev-erbα. Results: Abnormal exposure to light aggravated lipid deposition in liver of mice and exacerbated disorders related to 24-h expression levels of clock genes, autophagy-related genes, and Rev-erbα. Besides, Rev-erbα could transcriptionally control the expression levels of autophagy-related genes. Conclusions: The long-term high-fat diet combined with abnormal light/dark cycle stimulation aggravated the development of NAFLD and disturbed the expressions levels of autophagy-related genes. An abnormal circadian expression may lead to NAFLD aggression. Besides, the abnormal expression levels of clock genes may create an association between circadian rhythm sleep disorder and autophagy.

The response to a zeitgeber, particularly the light/dark cycle, may vary phenotypically. Phenotypic plasticity can be defined as the ability of one genome to express different phenotypes in response to environmental variation. In this opinion paper, we present some evidence that one of the most prominent effects of the introduction of electric light to the everyday life of humans is a significant increase in phenotypic plasticity and differences in interindividual phases of entrainment. We propose that the healthy limits of phenotypic plasticity have been surpassed in contemporary society., Highlights • Electric light increased phenotypic plasticity in humans and differences in interindividual phases of entrainment. • Healthy limits of phenotypic plasticity have been surpassed in contemporary society. • The correlation between biological time (DLMO) and behavioral time (MSFsc) is reduced in the population without access to electrical light.

Gut microbiota has been shown to involve in many physiological functions such as metabolism, brain development, and neuron degeneration disease. Intriguingly, many microbes in the digestive tract do not maintain a constant level of their relative abundance but show daily oscillations under normal conditions. Recent evidence indicates that chronic jetlag, constant darkness, or deletion of the circadian core gene can alter the composition of gut microbiota and dampen the daily oscillation of gut microbes. These studies suggest that the interaction between the host circadian clock and the light-dark cycle plays an important role in gut homeostasis and microbiota. However, how or whether environmental factors such as the light-dark cycle could modulate gut microbiota is still poorly understood. Using genetic mouse models and 16s rRNA metagenomic analysis, we found that light-dark cycle information transmitted by the ipRGC-sympathetic circuit was essential for daily oscillations of gut microbes under temporal restricted high fat diet condition. Furthermore, aberrant light exposure such as dim light at night (dLAN), acting through intrinsically photosensitive retinal ganglion cells (ipRGCs), could alter the composition, relative abundance, and daily oscillations of gut microbiota. Together, our results indicate that external stimulation, such as light-dark cycle information, through the sensory system can modulate gut microbiota in the direction from the brain to the gut.

Agricultural production is greatly dependent on daylength, which is determined by latitude. Living organisms align their physiology to daylength through the circadian clock, which is made up of input sensors, core and peripheral clock components, and output. The light/dark cycle is the major input signal, moderated by temperature fluctuations and metabolic changes. The core clock in plants functions mainly through a number of transcription feedback loops. It is known that the circadian clock is not essential for survival. However, alterations in the clock components can lead to substantial changes in physiology. Thus, these clock components have become the de facto targets of artificial selection for crop improvement during domestication. Soybean was domesticated around 5,000 years ago. Although the circadian clock itself is not of particular interest to soybean breeders, specific alleles of the circadian clock components that affect agronomic traits, such as plant architecture, sensitivity to light/dark cycle, flowering time, maturation time, and yield, are. Consequently, compared to their wild relatives, cultivated soybeans have been bred to be more adaptive and productive at different latitudes and habitats for acreage expansion, even though the selection processes were made without any prior knowledge of the circadian clock. Now with the advances in comparative genomics, known modifications in the circadian clock component genes in cultivated soybean have been found, supporting the hypothesis that modifications of the clock are important for crop improvement. In this review, we will summarize the known modifications in soybean circadian clock components as a result of domestication and improvement. In addition to the well-studied effects on developmental timing, we will also discuss the potential of circadian clock modifications for improving other aspects of soybean productivity.

For research on circadian intraocular pressure (IOP), rebound tonometers are widely used with or without general anesthesia as a non-invasive approach to obtain IOP values. However, whether general anesthesia such as inhalation anesthesia with isoflurane affects the circadian rhythm of IOP and in turn IOP measurements is currently unclear. As such, data reporting IOP values obtained under general anesthesia should be interpreted with caution. The purpose of this study was to evaluate how general anesthesia with isoflurane inhalation affects the circadian rhythm of IOP.C57Bl/6J strain mice maintained using a 12h:12h light/dark cycle (lights on and off at ZT0 and ZT12, respectively) were used. IOPs were measured using a rebound tonometer (Icare TonoLab) before and 3, 5, 10, 15, and 30 min after initiating anesthesia in both light and dark phases (ZT 2-6 and ZT 14-18, respectively). Awake IOPs and IOPs at 3 and 5 min after anesthesia initiation were also obtained at ZT5, 8, 11, 14, 17, and 20 to assess IOP diurnal curves under gas anesthesia.IOP values gradually decreased after anesthesia initiation in both light and dark phases (P 0.001) and there was no interaction between light/dark phase and anesthesia time (P = 0.88). There was a slight, but not significant, reduction in IOP 3 min after initiating anesthesia (P = 0.23), and significant decreases in IOP occurred at subsequent timepoints (P ≤ 0.001). Both awake and anesthetized mice showed a robust IOP rhythm that reached a peak and trough in the dark and light phase, respectively. Awake IOP levels did not significantly differ from those for anesthetized mice at 3 min after anesthesia initiation at all time points (P ≥ 0.07).Both awake and anesthetized mice demonstrated a robust circadian rhythm for IOP. Murine IOP showed similar gradual decreases under inhalation anesthesia with isoflurane in both the light and dark phases. IOPs measured using a rebound tonometer within 3 min of initiating isoflurane anesthesia were comparable to awake IOPs, and thus may be useful to monitor the circadian rhythm of IOP in mice.

Cereus jamacaru DC subsp. jamacaru (mandacaru) is an endemic species in Brazil belonging to Cactaceae of great ecological importance, as it is a pioneer in the colonization of arid and inhospitable environments, and contributes directly to the food chain for its fruits highly appreciated by fauna. Therefore, this work aimed to evaluate, through chemical scarification, the germinative behavior of C. jamacaru subsp. jamacaru. The cactus seeds were collected in May 2016 in the city of Quixelô-CE-Brazil. The acids used in chemical scarification were acetic acid, hydrochloric acid, propionic acid and sulfuric acid for 5, 10 and 15 minutes. The seeds were placed in Petri dishes, and placed to germinate in a B.O.D. with a light/dark cycle of 12 hrs at 30 ºC. Daily readings were performed and analyzed: percentage of germination, Germination Speed ​​Index (GSI) and mean germination time (Tm). The results indicate that acids negatively interfere in seed germination when compared to the control group, mainly acetic and propionic acid, since at the end of the experiment only 8% of the seeds germinated when subjected to acetic acid, and 4% to the propionic. In addition, there was also a significant increase in Tm. Thus, water is the best method of obtaining a higher percentage of germination of C. jamacaru subsp. jamacaru. Cereus jamacaru DC subsp. jamacaru (mandacaru) es una especie endémica en Brasil perteneciente a Cactaceae de gran importancia ecológica, ya que es pionera en la colonización de ambientes áridos e inhóspitos, y contribuye directamente a la cadena alimentaria por sus frutos muy apreciados por la fauna. Por tanto, este trabajo tuvo como objetivo evaluar, mediante escarificación química, el comportamiento germinativo de C. jamacaru subsp. jamacaru. Las semillas de cactus fueron recolectadas en mayo de 2016 en la ciudad de Quixelô-CE-Brasil. Los ácidos utilizados en la escarificación química fueron ácido acético, ácido clorhídrico, ácido propiónico y ácido sulfúrico durante 5, 10 y 15 minutos. Las semillas se colocaron en placas de Petri y se colocaron para germinar en un B.O.D. con un ciclo de luz/oscuridad de 12 ha 30 ºC. Se realizaron y analizaron lecturas diarias: porcentaje de germinación, índice de velocidad de germinación (IVG) y tiempo promedio de germinación (Tm). Los resultados indican que los ácidos interfieren negativamente en la germinación de las semillas en comparación con el grupo control, principalmente ácido acético y propiónico, ya que al final del experimento solo el 8% de las semillas germinaron al ser sometidas a ácido acético, y el 4% al propiónico. Además, también hubo un aumento significativo en Tm. Así, el agua es el mejor método para obtener un mayor porcentaje de germinación de C. jamacaru subsp. jamacaru. Cereus jamacaru DC subsp. jamacaru (mandacaru) é uma espécie endêmica do Brasil pertencente à Cactaceae de grande importância ecológica, por ser pioneira na colonização de ambientes áridos e inóspitos, e contribuir de forma direta na cadeia alimentar por seus frutos extremamente apreciados pela fauna. Sendo assim, este trabalho objetivou avaliar por meio de escarificação química o comportamento germinativo das sementes de C. jamacaru subsp. jamacaru. As sementes do cacto foram coletadas em maio de 2016 na cidade de Quixelô-CE-Brasil. Os ácidos utilizados nas escarificações química foram o ácido acético, ácido clorídrico, ácido propiônico e ácido sulfúrico durante 5, 10 e 15 minutos. As sementes foram acondicionadas em placas de Petri, e postas para germinar em câmara do tipo B.O.D. com um ciclo claro/escuro de 12 hrs a 30 ºC. Foram realizadas leituras diárias e analisadas: porcentagem de germinação, Índice de Velocidade de Germinação (IVG) e tempo médio para germinação (Tm). Os resultados apontam que os ácidos interferem de modo negativo na germinabilidade das sementes quando comparados com o grupo controle, principalmente o ácido acético e o propiônico, visto que ao final do experimento apenas 8% das sementes germinaram quando submetidas ao ácido acético, e 4% ao propiônico. Além disso, verificou-se também um aumentou significativo do Tm. Sendo assim, a água é o melhor método de se obter uma maior porcentagem de germinação de sementes de C. jamacaru subsp. jamacaru.

The digestive system presents daily rhythms at both physiological and histological levels. Although cell morphology rhythms in mammals have been reported, they have scarcely been investigated in fish. The aim of the present research was to investigate the existence of daily rhythms in the morphology of cells in the liver and intestine of a teleost fish, the European sea bass (Dicentrarchus labrax), and how feeding time influences them. Regarding liver, we also focused on differences between the two metabolic zones: perivenous and periportal. For this purpose, fish were divided into two groups: fish fed once a day in the mid-light phase (ML) or the mid-dark phase (MD). After 1 month under each feeding regime, liver and intestine samples were collected every 4 h during a 24-h cycle, and different parameters were studied by light microscopy and image analysis. Daily rhythms occurred in most of the parameters evaluated in the liver. The effect of feeding time depended on the metabolic zone: the rhythms in the periportal zone were synchronized mainly by the light/dark cycle regardless of feeding time, whereas in the perivenous zone, rhythms were influenced more by feeding time. In the intestine, a daily rhythm in villi height was found with acrophases coinciding with feeding time in each group. These findings show for the first time the existence of cellular morphological rhythms in fish liver and intestine, and highlight the interactions between light and feeding cycles in the different metabolic zones of the liver.

Background This research builds on the studies on ambient temperature as a key influence in the recovery of rodents exposed to the activity-based anorexia (ABA) model. The ABA model is an experimental paradigm in which rodents under a restricted feeding schedule and with free access to an activity wheel show signs that parallel those of anorexia nervosa in humans. Objective The present study focuses on the effects of applying heat during the different phases of the dark-light cycle in the activity levels, body weight, food intake, body temperature, and recovery rates of 30 male rats submitted to ABA. Method After reaching a 20% weight loss criterion, animals were randomly assigned to three experimental conditions: (a) continuous warming, (b) warming exclusively during the light phase, or (c) warming exclusively during the dark phase. Results Differential effects were found depending on the modalities of warming: in comparison with either light or dark warming, continuous warming significatively decreased activity, facilitated weight gain, and maintained body temperature. Transient effects of warming were found both in the groups warmed either during light or dark periods exclusively. Discussion The results suggest that both light and dark warming did not promote recovery in animals exposed to ABA. Evidence about the beneficial effects of continuous warming are in line with previous research and reinforces adding external heat as a useful tool in the treatment of anorexia nervosa.

Circadian rhythms have evolved to produce cyclic changes in metabolism or behavior that adapt the body to changing requirements throughout the 24 h light/dark cycle. Here, we highlight recent advances in our understanding of the mechanisms that maintain body hydration and highlight the contribution of the central clock to the generation of endocrine and behavioral rhythms that contribute significantly to this process.

“Musica universalis” is an ancient philosophical concept claiming the movements of celestial bodies follow mathematical equations and resonate to produce an inaudible harmony of music, and the harmonious sounds that humans make were an approximation of this larger harmony of the universe. Besides music, electromagnetic waves such as light and electric signals also are presented as harmonic resonances. Despite the seemingly universal theme of harmonic resonance in various disciplines, it was not until recently that the same harmonic resonance was discovered also to exist in biological systems. Contrary to traditional belief that a biological system is either at stead-state or cycles with a single frequency, it is now appreciated that most biological systems have no homeostatic “set point,” but rather oscillate as composite rhythms consisting of superimposed oscillations. These oscillations often cycle at different harmonics of the circadian rhythm, and among these, the ~12-hour oscillation is most prevalent. In this review, we focus on these 12-hour oscillations, with special attention to their evolutionary origin, regulation, and functions in mammals, as well as their relationship to the circadian rhythm. We further discuss the potential roles of the 12-hour clock in regulating hepatic steatosis, aging, and the possibility of 12-hour clock–based chronotherapy. Finally, we posit that biological rhythms are also musica universalis: whereas the circadian rhythm is synchronized to the 24-hour light/dark cycle coinciding with the Earth’s rotation, the mammalian 12-hour clock may have evolved from the circatidal clock, which is entrained by the 12-hour tidal cues orchestrated by the moon., We focus on 12-hour oscillations, with special attention to their evolutionary origin, regulation, and functions in mammals, as well as their relationship to the circadian rhythm.

The current body of work on rearing larval/juvenile zebrafish is based on (1) utilization of freshwater and (2) diurnal light/dark cycle, (3) provision of live feed at modest density, and (4) culture in high visibility environment. We challenged these rearing approaches by maintaining zebrafish under constant light for 46-48 days (days postfertilization [dpf]), while securing continuous feeding in high turbidity and saline (1.8-2.1 parts per thousand) environment for the experiment's duration, allowing 24 h feeding/growth of fish from first exogenous feeding to maturation. There was no evidence of negative effects on zebrafish larvae behavior, growth, survival, and life cycle duration at constant illumination when food was continuously available. Zebrafish were stocked at high initial density (100 larvae/L) in a static system and fed high densities of rotifers (Brachionus plicatilis) (200-400/mL) from 6 to 12 dpf. Fish density was then reduced by 50% and two diet treatments, live rotifers or brine shrimp (Artemia) nauplii (10/mL), followed. Fish were reared on these two diets until first maturation. Performance of adult zebrafish fed live rotifer followed by Artemia nauplii diet was the highest recorded in the literature after 42 dpf, 250 ± 29 (males) and 430 ± 5 mg (females). Use of these rearing conditions, during the entire life cycle, until reproduction, resulted in the shortest ever recorded generation time (from egg to egg) of 43-45 dpf and fertilization rate (1 dpf) of 80.3%-94%.

Highlights • Automated assessment of mouse home-cage behaviour is robust and reliable. • Analysis over multiple light/dark cycles improves ability to classify behaviours. • Combined RFID and video analysis enables home-cage analysis in group housed animals., An important factor in reducing variability in mouse test outcomes has been to develop assays that can be used for continuous automated home cage assessment. Our experience has shown that this has been most evidenced in long-term assessment of wheel-running activity in mice. Historically, wheel-running in mice and other rodents have been used as a robust assay to determine, with precision, the inherent period of circadian rhythms in mice. Furthermore, this assay has been instrumental in dissecting the molecular genetic basis of mammalian circadian rhythms. In teasing out the elements of this test that have determined its robustness – automated assessment of an unforced behaviour in the home cage over long time intervals – we and others have been investigating whether similar test apparatus could be used to accurately discriminate differences in distinct behavioural parameters in mice. Firstly, using these systems, we explored behaviours in a number of mouse inbred strains to determine whether we could extract biologically meaningful differences. Secondly, we tested a number of relevant mutant lines to determine how discriminative these parameters were. Our findings show that, when compared to conventional out-of-cage phenotyping, a far deeper understanding of mouse mutant phenotype can be established by monitoring behaviour in the home cage over one or more light:dark cycles.

Little research has been done on egg diapause and the embryonic development of water mites. The aim of this study was to check the impact of temperature and periods of light on hatching of larvae of Eylais extendens. Three batches of eggs which were spawned on 30 July were placed at one of three temperatures (4, 10 and 20 °C) and two periods of light (7 and 14 h per day). Egg hatching (both, percentage of hatched larvae and rate of hatching) was found to differ between 4 versus 10 °C and between 4 versus 20 °C, but not between 10 versus 20 °C. The periods of light had no influence on hatching. This synchronization of hatching, enabling the eggs to emerge from diapause in the spring, could be considered an evolutionary adaptation aimed at postponing hatching of late-spawned eggs until a time allowing for completion of the full development cycle, including the parasitic larval stage.

Correct operation of the plant circadian clock is crucial for optimal growth and development. Recent evidence has shown that the plant clock is tissue-specific and potentially hierarchical, implying that there are signalling mechanisms that can synchronise the clock in different tissues. Here I have addressed the mechanism that allows the shoot and root clocks to be synchronised in light:dark cycles but not in continuous light. Luciferase imaging data from two different Arabidopsis accessions with two different markers show that the period of the root clock is much less sensitive to blue light than to red light. Decapitated roots were imaged either in darkness or with the top section of root tissue exposed to light. Exposure to red light reduced the period of the root tissue maintained in darkness whereas exposure to blue light did not. The data indicate that light can be piped through root tissue to affect the circadian period of tissue in darkness. I propose that the synchronisation of shoots and roots in light:dark cycles is achieved by light piping from shoots to roots.

This study aimed to clarify the effect of light exposure during the daytime and nighttime on diet-induced thermogenesis (DIT), which is one kind of energy expenditure, and the contribution of autonomic nervous activities (ANA) to the mechanism behind such effects. We found that the light-dark cycle significantly induced a diurnal rhythm of DIT, with afternoon levels tending to be higher than nighttime levels. By contrast, no such rhythms were observed under constant light or dark conditions. There were also no significant differences in ANA between the light conditions. These findings demonstrate that a diminished light-dark cycle leads to disruption of the diurnal rhythm of metabolism and so the retention of ordinary light-dark cycles may be recommended for health maintenance.

Physiological variables such as heart rate (HR) and blood pressure (BP) exhibit long-term circadian rhythms, which can be disturbed by shift work. On the other hand, short-term oscillations in HR and BP have a high prognostic value. Therefore, we aimed to determine if the short-term variability, complexity and entropy of HR and BP would be affected by a regular light/dark (LD) cycle and phase delay shifts of the LD cycle, leading to chronodisruption. Telemetry-monitored rats were exposed first to the regular LD cycle and then to shifts in LD for 8weeks. On the basis of long-term HR and BP recording and evaluation, we found circadian rhythms in HR and BP variability, complexity and entropy under regular LD cycles. Short-term exposure to shifts disturbed circadian rhythms of HR and BP variability, complexity and entropy, indicating chronodisruption. The power of circadian rhythms was suppressed after 8weeks of phase delay shifts. Long-term exposure to shifts increased variability (p=0.007), complexity (p

In the present work, a lab scale photobioreactor was used to evaluate lipid productivity and carbon dioxide fixation rate of microalgae Chlorella protothecoides under nitrogen deplete conditions. Effect of environmental conditions such as pH, temperature, light intensity, photoperiod (light to dark cycle ratio), CO 2 concentration in air and aeration rate on lipid productivity and carbon fixation rate of microalga was studied. Response surface methodology was adopted to optimize these conditions. All the parameters were found to be statistically significant. Best operating conditions were evaluated to be: pH-6.51, Temperature-28.63 °C, light intensity-5.31 klux, Photoperiod-15.36 h:8.64 h, CO 2 concentration in air-6.26% (v/v), Aeration rate −2.92 lpm. Lipid productivity under these conditions was found to be 274.15 mg/(L day) which was 3.94 times higher than the value obtained in N+ experiment (69.46 mg/(L day)). Carbon fixation rates under N+ and N− conditions were 286.12 and 273.66 mg/(L day) respectively.

Light is the most potent time cue that synchronizes (entrains) the circadian pacemaker to the 24-h solar cycle. This entrainment process is an interplay between an individual's daily light perception and intrinsic pacemaker period under free-running conditions. Establishing individual estimates of circadian phase and period can be time-consuming. We show that circadian phase can be accurately predicted (SD = 1.1 h for dim light melatonin onset, DLMO) using 9 days of ambulatory light and activity data as an input to Kronauer's limit-cycle model for the human circadian system. This approach also yields an estimated circadian period of 24.2 h (SD = 0.2 h), with longer periods resulting in later DLMOs. A larger amount of daylight exposure resulted in an earlier DLMO. Individuals with a long circadian period also showed shorter intervals between DLMO and sleep timing. When a field-based estimation of tau can be validated under laboratory studies in a wide variety of individuals, the proposed methods may prove to be essential tools for individualized chronotherapy and light treatment for shift work and jetlag applications. These methods may improve our understanding of fundamental properties of human circadian rhythms under daily living conditions.

Sequestration of CO 2 by microalgae is one of the technically viable options to control the CO 2 emission. CO 2 sequestration by microalgae through photosynthesis also results in large quantity of biomass production with considerable fuel properties. Different types of micro algal species have got CO 2 tolerance to a different level. This work focuses on the tolerance capability of Oscillatoria sp. for 100% CO 2 , bubbled into the ASN III media. CO 2 supply was given at a flow rate of 300 ml/min for 15 min. 12:12 h of light to dark cycle was followed.CO 2 supply was varied from one to three times a day during the light period. An increasing trend of biomass growth was observed with increased supply frequency of CO 2 . An increase of biomass yield of 44.7%, CO 2 fixation of 64.2% and calorific value of 17.6% was observed corresponding to the three times supply frequency of CO 2 , compared with the control. Ultimate analysis, stoichiometric analysis and molecular weight of microalgae grown in control and pure CO 2 (100%) gas were compared. Growth of microalgae obtained at various supply frequencies of CO 2 were fitted with logistic model with a correlation coefficient of 0.98. The present studies indicated that the Oscillatoria sp. was able to sustain in pure CO 2 (100%) gas and may be considered as the species for converting the emissions from the distilleries to energy.

In mammals, memory acquisition and retrieval can be affected by time of day, as well as by manipulations of the light/dark cycle. Under bifurcation, a manipulation of circadian waveform, two subjective days and nights are experimentally induced in rodents. We examined the effect of bifurcation on Pavlovian fear conditioning, a prominent model of learning and memory. Here we demonstrate that bifurcation of the circadian waveform produces a small deficit in acquisition, but not on retrieval of fear memory. In contrast, repeated phase-shifting in a simulated jet-lag protocol impairs retrieval of memory for cued fear. The results have implications for those attempting to adjust to shift-work or other challenging schedules.

Some major aspects of insect life, like development time and reproduction, can benefit from fluctuating temperatures rather than a constant temperature regime. The benefit of fluctuating temperature has generally been attributed to the non-linear properties of the relationship of many life history traits with temperature. Daily temperature rise, however, usually coincide with the light phase of the photoperiodic cycle and there could be a benefit in linking daily temperature fluctuations with light and dark phases e.g. to anticipate the change in temperature. Such synergistic effects have primarily been studied in the light of activity patterns and gene expression, but have not yet been shown to extend to population dynamics and aspects of individual fitness like oviposition behavior. We therefore explored possible synergistic effects on life history traits of the springtail Orchesella cincta. We first test the primary effect of ecologically relevant temperature fluctuations of different amplitudes on population growth and total population mass. The slowest population growth was observed in the constant temperature regime treatment and the highest population growth in the regime with high amplitude fluctuations. In a second experiment, population growth and oviposition rhythm were measured under four different regimes; a constant light and temperature regime, thermoperiod only, photoperiod only and thermoperiod and photoperiod aligned as under natural conditions. The regime in which thermoperiod was aligned with photoperiod resulted in a higher population growth than could be realized by either factor alone. Also, significantly fewer eggs were laid in the constant temperature/light regime than in the other three regimes, strongly suggesting that this regime is stressful to O. cincta. Additionally, the fraction of eggs laid at night was highest in the regime with the combined temperature and light cycle. In conclusion, our results show that under these experimental conditions there is a synergistic effect of daily temperature fluctuations in combination with light/dark phases that can considerably influence important life history traits and affect behavior. Such effects are likely to be relevant under natural conditions.

Non-24-hour sleep-wake rhythm disorder (N24SWD) occurs when the intrinsic circadian pacemaker does not entrain (synchronize) to the 24-hour light/dark cycle. There is currently no established treatment for sighted patients with N24SWD. To the best of our knowledge, there have been very few reports on the efficacy of ramelteon administered to sighted patients with N24SWD. We report the case of a sighted patient with N24SWD whose free-running sleep-wake pattern recorded by actigraphy was stopped after the administration of a low dose of ramelteon combined with behavioral education.

Genetically encoded biological clocks are found broadly throughout eukaryotes and in cyanobacteria, where they generate circadian (about a day) rhythms that allow organisms to anticipate regular environmental changes and align their physiology and behavior with Earth's daily light/dark cycle. In recent years, many have sought to expand our biochemical and structural understanding of the clock proteins that constitute the molecular “cogs” of these biological clocks. These new studies are beginning to reveal how macromolecular assemblies of dedicated clock proteins form and evolve to contribute to the generation of clocks that function over the timescale of a day. This review will highlight structural and biochemical studies that provide important insight into the molecular mechanisms of cyanobacterial and vertebrate animal clocks. Collectively, these studies demonstrate emerging biochemical properties that appear to be shared by these different clocks, suggesting that there may be some conservation in the regulation and assembly of circadian macromolecular assemblies.