Nycthemeral Rhythm Research Articles

Rhythmicity is linked to expression cost at the protein level but to expression precision at the mRNA level.

Many genes have nycthemeral rhythms of expression, i.e. a 24-hours periodic variation, at either mRNA or protein level or both, and most rhythmic genes are tissue-specific. Here, we investigate and discuss the evolutionary origins of rhythms in gene expression. Our results suggest that rhythmicity of protein expression could have been favored by selection to minimize costs. Trends are consistent in bacteria, plants and animals, and are also supported by tissue-specific patterns in mouse. Unlike for protein level, cost cannot explain rhythm at the RNA level. We suggest that instead it allows to periodically reduce expression noise. Noise control had the strongest support in mouse, with limited evidence in other species. We have also found that genes under stronger purifying selection are rhythmically expressed at the mRNA level, and we propose that this is because they are noise sensitive genes. Finally, the adaptive role of rhythmic expression is supported by rhythmic genes being highly expressed yet tissue-specific. This provides a good evolutionary explanation for the observation that nycthemeral rhythms are often tissue-specific.

Benefit of a healing garden on sleep in neurocognitive diseases

Progressive neurocognitive pathologies frequently alter the architecture of sleep with: advanced sleep phase or phase delay, sleep fragmentation, decrease of slow-wave sleep, REM sleep, nocturnal agitation and wandering or even complete reversal of the nycthemeral rhythm. This has a clear impact on the health and quality of life of the patient. Hospitalization increases the risk of sleep disturbances due to inactivity, some sensory deprivation and daytime hypovigilance. The therapeutic gardens offer in an attractive, sensorially stimulating setting and exposed to natural light, the possibility of an adapted physical exercise. Their impact on the quality and quantity of sleep in cognitive-behavioral units has been evaluated in an exploratory manner. The hypnogram of two groups of 30 patients was compared depending on whether they used the garden (weather permitting, in summer) or not (in winter). The results show that the patients who use the garden are significantly more active during the day, have a longer nighttime sleep duration and are less restless at night. In addition, patients who use and walk longer in the garden benefit from an increase in their sleep time. In view of their multiple interests, therapeutic gardens, if they meet validated design criteria, should be integrated more widely into establishments welcoming people with neurocognitive diseases.

Daily and seasonal time partitioning in surface activity of Porcellioalbinus (Isopoda, Oniscidea) in the arid region of Zarat (Gabes, Tunisia).

The terrestrial isopod Porcellioalbinus is a burrowing species, dwelling in the desert of south Tunisia. Field studies were carried out in the coastal area of Zarat, Tunisia, to examine the surface activity rhythm of P.albinus in relation to daily and seasonal variations in environmental conditions. The activity of P.albinus was followed once a month, from November 2012 through October 2013. Hourly capture frequency was compared across the different seasons of the year. Porcellioalbinus is a strictly nocturnal species showing a nycthemeral rhythm regulated by the rhythmic and natural variations of the duration of the dark period. A positive correlation is observed between the circadian rhythm of the locomotor activity of the species and the duration of the dark period outside its burrow, P.albinus has a single daily activity peak. Individuals concentrated their activity in the first part of the night in winter and in the second part in summer. This peak is more spread out in spring and autumn. The differences in the activity rhythm of P.albinus between different seasons may be determined by two important factors, namely temperature and the length of the dark period.

Electrophysiological assessment of plant status outside a Faraday cage using supervised machine learning

Living organisms have evolved complex signaling networks to drive appropriate physiological processes in response to changing environmental conditions. Amongst them, electric signals are a universal method to rapidly transmit information. In animals, bioelectrical activity measurements in the heart or the brain provide information about health status. In plants, practical measurements of bioelectrical activity are in their infancy and transposition of technology used in human medicine could therefore, by analogy provide insight about the physiological status of plants. This paper reports on the development and testing of an innovative electrophysiological sensor that can be used in greenhouse production conditions, without a Faraday cage, enabling real-time electric signal measurements. The bioelectrical activity is modified in response to water stress conditions or to nycthemeral rhythm. Furthermore, the automatic classification of plant status using supervised machine learning allows detection of these physiological modifications. This sensor represents an efficient alternative agronomic tool at the service of producers for decision support or for taking preventive measures before initial visual symptoms of plant stress appear.

Azadirachtin impact on mate choice, female sexual receptivity and male activity in Drosophila melanogaster (Diptera: Drosophilidae)

Azadirachtin, a neem compound (Azadirachta indica) with medical and anti-insect properties, is one the most successful botanical pesticides in agricultural use. However, its controversial impact on non-targeted species and its mechanism of action need to be clarified. In addition, Azadirachtin impact on pre- and post-mating traits remains largely undocumented. The current study examined the effects of Azadirachtin on Drosophila melanogaster as a non-target and model species. Azadirachtin was applied topically at its LD50 (0.63μg) on the day of adult emergence and its effect was evaluated on several traits of reproductive behavior: mate choice, male activity, female sexual receptivity, sperm storage and female sterility. In choice and no choice conditions, only male treatment reduced mating probability. Female treatment impaired mating probability only when males had the choice. Males' mating ability may have been impaired by an effect of the treatment on their mobility. Such an effect was observed in the actimeter, which revealed that treated males were less active than untreated ones, and this effect persisted over 8days. Azadirachtin treatment had, however, no effect on the nycthemeral rhythm of those males. Even when mating occurred, Azadirachtin treatment impaired post-mating responses especially when females or both sexes were treated: remating probability increases and female fertility (presence of larvae) decreases. No impairment was observed on the efficiency of mating, evaluated by the presence of sperm in the spermatheca or the ventral receptacle. Male treatment only had no significant effect on these post-mating responses. These findings provide clear evidence that Azadirachtin alters the reproductive behavior of both sexes in D. melanogaster via mating and post-mating processes.

Nycthemeral Rhythm of Phlebotominae (Diptera: Psychodidae) in a Craggy Region, Transitioning Between the Wetland and the Plateau, Brazil.

Recording the nycthemeral rhythm of sand flies allows the evaluation of the daily activity in different ecotypes, the period of greatest activity, and their degree of anthropophily. We investigated the fauna and the rhythm of sand fly activity in an ecotourism region in Mato Grosso do Sul (MS) state, Brazil. Sand flies were captured monthly, using a Shannon trap for 24 h periods between July 2012 and June 2014. We collected 1,815 sand flies, in which Lutzomyia whitmani (=Nyssomyia whitmani, sensu Galati) and Lutzomyia longipalpis were the most abundant species during the dry season, with activity from 5 p.m.-7 a.m. and 6 p.m.-5 a.m., respectively. Both species require particular attention as vectors of Leishmania (Viannia) braziliensis and Leishmania (Leishmania) infantum in several regions of Brazil, including MS. However, Lutzomyia dispar was more anthropophilic, and was most active between January and March, from 5 p.m. to 5 a.m. Lutzomyia misionensis (=Pintomyia misionensis, sensu Galati) was present throughout both years, active from 4 p.m. to 5 a.m. Other species were active from 5 p.m. to 6 a.m. Due to intense tourism in the months that coincide with a high number of vectors for leishmaniases in Piraputanga, it is essential to determine vector-monitoring strategies in the area by investigating sand fly rhythm while not neglecting other periods of the year when the insects are present.

Daily profiles of steroid hormones and their metabolites related to food intake.

The aim of this study was to look for changes in the daily profile of steroid hormones after standardized food intake. Eight young women not taking contraceptives were followed from 5:30 a.m. till 9:30 p.m. before and 1 and 2 h after eating breakfast, snack, lunch, the second snack and dinner. The differences in steroid levels before and after meals were evaluated. As expected, glucose, C-peptide and ghrelin levels changed postprandially. The steroid hormones cortisol, progesterone, pregnenolone and dehydroepiandrosterone showed a decrease after main meals, whereas testosterone and dihydrotestosterone showed no significant dependence on food intake. Estrogen levels did not exhibit a significant nycthemeral rhythm, but estradiol decreased after main meals. In our study the known nycthemeral rhythm of LH, FSH, cortisol, progesterone and pregnenolone after food intake were confirmed, but significant changes after meals were also observed in the levels of cortisol, dehydroepiandrosterone, estradiol and SHBG.

Positive effects of the traditional Chinese medicine MLC901 in cognitive tasks.

MLC901 (NurAiDII) is used as a treatment for stroke patients. It has been shown that MLC901 improves motor and cognitive recovery in ischemic and traumatic brain‐injured rodents. The present study seeks to delineate cognitive effects induced by MLC901 in normal, noninjured mice. To this end, the behaviors of vehicle‐ and MLC901‐treated C57BL/6 mice in hippocampus‐dependent (passive avoidance, Morris water maze) and hippocampus‐independent (novel object recognition) cognitive tasks are compared. The potential influence of the compound on the anxiety level and nycthemeral rhythm of mice is also assessed. In addition, the long‐term effects of MLC901 on hippocampal neurogenesis are measured. The results clearly demonstrate that MLC901 promotes extinction in passive avoidance and reversal learning in the Morris water maze and improves the performance of mice in novel object recognition. In parallel, this study shows the long‐term proneurogenesis effects of MLC901 that result in the increase in the number of mature neurons in the hippocampus. If these observations can be extended to humans, then MLC901 could represent a promising therapeutic strategy. © 2015 The Authors. Journal of Neuroscience Research Published by Wiley Periodicals, Inc.

Alterations of circadian rhythms of thyroid-stimulating hormone, thyroid, adrenal and insulin hormones, and blood glucose profiles following lithium treatment in alternate Light–Dark, constant Light and constant Dark regimens in rats

Lithium, widely used for the treatment of mania, has adverse side effects on circadian rhythms of pineal and testicular hormones. Objective was to examine the role of lithium on circadian rhythms of other hormones and glucose profiles in light–dark (12L:12D), constant light (12L:12L) and constant dark (12D:12D) regimens in rats. Intraperitoneal injection of lithium (2 mEq/kg body wt daily for 15 days) sustained circadian rhythms of T3, T4, thyroid-stimulating hormone (TSH), corticosterone, norepinephrine and epinephrine in light–dark and constant dark but not in constant light. But it abolished circadian rhythms of insulin and blood glucose in all the photoperiodic regimens, except insulin, without changing their pattern in constant dark. Patterns of circadian rhythms of thyroid and TSH, and adrenal hormones remained unchanged after lithium treatment in L–D or D–D, except TSH in L–D. The probable role of photoperiodic cue and lithium on circadian and/or nycthemeral (daily) rhythms of hormones and blood glucose profiles is discussed.

Corticotroph deficiency

Corticotroph deficiency usually results from exogenous glucocorticoid therapy or, more rarely, from hypothalamopituitary damages. Its diagnostic may be difficult, especially when the deficit in ACTH secretion is partial. Stimulation tests are then necessary to investigate the integrity of the hypothalamopituitary-adrenal axis. The insulin tolerance test has become the gold standard, but its utilization is limited by several contra-indications. The metyrapone and cosyntropin tests represent currently used alternatives but their sensitivity is not optimal. Measurement of basal plasma dehydroepiandrosterone sulfate may allow excluding corticotroph deficiency when normal. Finally, cortisol replacement in patients with corticotropic deficiency is based on hydrocortisone administration. However, the dose regimens employed in clinical practice do not allow mimicking the nycthemeral rhythm of cortisol secretion and are still disputed.

Solar Elevation Triggers Foraging Activity in a Thermophilic Ant

Nycthemeral rhythm is an important biological trait that allows animals to escape predation and competition and, conversely, to coincide with mutualists. Although laboratory studies have shown that the rhythm depends on both endogenous factors and cyclic environmental cues, the latter is often poorly understood, particularly in the wild. Because insects are mostly ectothermal organisms, their activity rhythm is often thought to depend directly on ground temperature. In Mediterranean habitats, Cataglyphis ants are well known for their unusual thermoresistance, allowing them to forage in summer at the central hours of the day when the ground reaches temperatures that are lethal to their competitors. However, we show that the rhythm of Cataglyphis floricola in south-western Spain is governed by light cues rather than by temperature. First, variations in ant traffic at the nest entrance were better explained by solar elevation angle than by ground temperature on both seasonal and daily scales. Second, if ants waited for the ground to reach a threshold temperature to start their activity, we would expect similar temperatures regardless of the opening hour. However, we found a significant increase in ground temperature as opening hour got later in the day. Third, by using a simple experimental set-up that increased the apparent solar elevation over the nest entrance, we provoked a delay of nest closure time. We discuss the relevance of these results with respect to the life history of Cataglyphis species and their possible consequences in relation to global warming.

Daily body temperature rhythms persist under the midnight sun but are absent during hibernation in free-living arctic ground squirrels

In indigenous arctic reindeer and ptarmigan, circadian rhythms are not expressed during the constant light of summer or constant dark of winter, and it has been hypothesized that a seasonal absence of circadian rhythms is common to all vertebrate residents of polar regions. Here, we show that, while free-living arctic ground squirrels do not express circadian rhythms during the heterothermic and pre-emergent euthermic intervals of hibernation, they display entrained daily rhythms of body temperature (T(b)) throughout their active season, which includes six weeks of constant sun. In winter, ground squirrels are arrhythmic and regulate core body temperatures to within ±0.2°C for up to 18 days during steady-state torpor. In spring, after the use of torpor ends, male but not female ground squirrels, resume euthermic levels of T(b) in their dark burrows but remain arrhythmic for up to 27 days. However, once activity on the surface begins, both sexes exhibit robust 24 h cycles of body temperature. We suggest that persistence of nycthemeral rhythms through the polar summer enables ground squirrels to minimize thermoregulatory costs. However, the environmental cues (zeitgebers) used to entrain rhythms during the constant light of the arctic summer in these semi-fossorial rodents are unknown.

Nycthemeral rhythms of total locomotor activity and oxidative markers in horse

Summary The aim of this study was to investigate the nycthemeral rhythm of total locomotor activity (TLA) in horse and the possible involvement of the daily organization of rest/activity cycles in the fluctuation of the redox state. For this purpose we recorded TLA and determined oxidative markers in ten clinically healthy Italian Saddle horses. TLA was continuously recorded by means of an actigraphy-based data logger (Actiwatch-Mini ® ). For the assessment of free radicals (dROMs), the antioxidant barrier (Oxy-ads) and the thiol-antioxydant barrier (SHp), blood samples were collected every 4 hours over a 48 h period. One-way repeated measures analysis of variance (ANOVA) showed a statistically significant effect of time of day on all studied parameters. The application of the periodic model and the statistical analysis of cosinor indicate, in horses, the existence of a daily rhythm of the studied parameters during the 48 h of monitoring. The results show that nycthemeral rhythms of TLA and oxidative markers have different trends in horse. dROMs and Oxy-ads showed a nycthemeral rhythm with an acrophase in the middle of the photophase, and the acrophase of SHp nycthemeral rhythm preceded them. In contrast, TLA showed its acrophase only after the middle of the photophase. TLA showed a lower robustness of rhythms (16.3 and 20.3%) and in respect to the robustness values of the rhythms of oxidative markers (67.3–86.2%). In conclusion, the results of the present investigation showed that oxidative markers have different patterns than locomotor activity, and further studies could be necessary to determine whether other external stimuli, such as solar radiation, food administration or physical exercise are able to influence redox state rhythms in this species.

Video tracking in the extreme: A new possibility for tracking nocturnal underwater transparent animals with fluorescent elastomer tags

Initially developed so that an individual could be recognized in mark-recapture studies of aquatic animals, fluorescent visible implant elastomer (VIE) tags are used here for a new application in ethometry: the study of the behavior of transparent animals in dim light or in darkness using automatic tracking technology. The application and validation of this multitracking method is tested in the context of research on the estuarine migratory behavior of the glass eel (Anguilla anguilla), a crucial point to better understand the dynamics of this endangered species. The method makes it possible to measure the activity (notably the distance and speed) of four individuals as a function of tidal and nycthemeral rhythms in the same flume (a circular aquarium simulating river or estuarine conditions) across a wide time scale (from seconds to weeks).

Statistical methods for detecting and comparing periodic data and their application to the nycthemeral rhythm of bodily harm: A population based study

BackgroundAnimals, including humans, exhibit a variety of biological rhythms. This article describes a method for the detection and simultaneous comparison of multiple nycthemeral rhythms.MethodsA statistical method for detecting periodic patterns in time-related data via harmonic regression is described. The method is particularly capable of detecting nycthemeral rhythms in medical data. Additionally a method for simultaneously comparing two or more periodic patterns is described, which derives from the analysis of variance (ANOVA). This method statistically confirms or rejects equality of periodic patterns. Mathematical descriptions of the detecting method and the comparing method are displayed.ResultsNycthemeral rhythms of incidents of bodily harm in Middle Franconia are analyzed in order to demonstrate both methods. Every day of the week showed a significant nycthemeral rhythm of bodily harm. These seven patterns of the week were compared to each other revealing only two different nycthemeral rhythms, one for Friday and Saturday and one for the other weekdays.

Effects of flooding of the River Paraná on the temporal activity of Anopheles (Nyssorhynchus) darlingi Root (Diptera: Culicidae), at the border state of Mato Grosso do Sul and São Paulo, Brazil

Study of the temporal activity of malaria vectors during the implantation of a hydroelectric power station on the River Paraná, intended to generate electrical energy. The river separates the States of São Paulo and Mato Grosso do Sul, in Brazil. The objective was to verify whether alterations occurred in the wealth and diversity indices of Anopheles, following two successive floods, extended to the temporal activity and nycthemeral rhythm followed over a five year period. Mosquito capture was performed monthly using the Human Attraction Technique and Shannon Traps. The first, executed for 24h, provided the nycthemeral rhythm and the second, lasting 15 h, permitted the tracking of Anopheles during the two floods. The bimodal pattern of Anopheles darlingi defined before these floods was modified throughout the environment interventions. The same effect had repercussions on the populations of An albitarsis s.l., An triannulatus and An galvaoi. Activity prior to twilight was less affected by the environment alterations. The dam construction provoked changes in Anopheles temporal activity patterns, permitting classification of the area as an ecologically steady and unstable situation. Differences observed in Anopheles behavior due to the capture methods revealed the influence of solo and multiple attractiveness inside the populations studied.

LONG-TERM ALTERATION OF DAILY MELATONIN, 6-SULFATOXYMELATONIN, CORTISOL, AND TEMPERATURE PROFILES IN BURN PATIENTS: A PRELIMINARY REPORT

Melatonin, which shows a robust nycthemeral rhythm, plays the role of an endogenous synchronizer, able to stabilize and reinforce circadian rhythms and maintain their mutual phase relationships. Additionally, melatonin is a potent antioxidant and displays immunological properties. Because free radical generation, immune dysfunction, and sleep and metabolic disorders are involved in the short- and long-term pathophysiology of the burn syndrome, we undertook the study of daily urine melatonin, 6-sulfatoxymelatonin (aMT6s, the main hepatic melatonin metabolite), and cortisol variations plus temperature profiles in burn patients using a non-invasive protocol. Eight patients (6 males, 2 females) were studied on three occasions after admission to the intensive care unit (early session: days 1 to 3; intermediate session: day 10; late session: days 20 to 30). Melatonin, aMT6s, and free cortisol levels were determined in urine samples collected at 4 h intervals over a continuous 24 h span. Core temperature was recorded daily. Controls consisted of healthy subjects in the same age range. Cosinor analysis of the data provided an evaluation of mesor, amplitude, and acrophase of circadian rhythms. Also, we calculated day (D), night (N), and 24 h hormone excretions, N/D ratio for melatonin and aMT6s, and D/N ratio for cortisol. These data were analyzed using Kruskal-Wallis test followed by multiple comparisons. Cosinor analysis did not detect a circadian rhythm in melatonin, aMT6s, or cortisol in any of the three sessions. D melatonin excretion displayed a major increase, resulting in a decreased N/D melatonin ratio, and the melatonin mesor (24 h mean) was increased in the early session, compared with controls. For aMT6s, only the early N/D ratio was decreased, and the mesor of the intermediate session increased. These results were not the consequence of hepatic and/or kidney alteration, as the patients' hepatic and renal parameters were in the normal range. The D and N melatonin/aMT6s ratios of controls and patients were similar, and the aMT6s profiles were superimposed on the melatonin ones, mainly during the day. The D, N, and 24 h cortisol values were increased in all sessions, except for the D level of the early session. The consistently increased mesors in the three sessions provided confirmation. The core temperature profiles were abnormal in all three sessions, mainly during the night, although there was a tendency toward normalization with time. The individual mesors were consistently increased compared with controls. Globally, the abnormalities we report could participate in the pathophysiology of short- and long-term alterations observed in burn syndrome, especially disturbances of sleep, metabolism, and immune function. (Author correspondence: bruno.claustrat@chu-lyon.fr).

Contribution of the daily melatonin profile to diagnosis of tumors of the pineal region

Tumors of the pineal region (TPR) include different entities: germ cell tumors (GCT), pineal parenchymal tumors (PPT), meningiomas, and glial tumors. Except for GCT, there are no peripheral markers and histopathological diagnosis needs biopsy or surgery. We studied daily melatonin variations in twenty-nine patients with TPR and five with tectal plate glioma (TPG), used as controls, before and/or after surgery. Before surgery, a melatonin nycthemeral rhythm was observed in patients with TPG and TPR (one cyst, three PPT, one papillary tumor of the pineal region, two meningiomas, six gliomas). Melatonin rhythm was dramatically reduced for undifferentiated or invasive tumors. After surgery, the absence of melatonin variation in some cases could be the consequence of pineal damage by surgery. The contribution of determination of melatonin profiles to the diagnosis of TPR remains limited but of interest. The evidence for melatonin deficiency could justify melatonin administration to prevent the postpinealectomy syndrome.

Effects of branched-chain amino acids supplementation on physiological and psychological performance during an offshore sailing race

The aim of the present study was to investigate the effect of protein diets, rich in branched chain amino acids (BCAA) on perceived exertion, mental and physical performance during an offshore sailing race that lasted 32 h. Twelve sailors were randomly allocated into one of two groups [Control (CON) and BCAA: n = 6/group]. The BCAA group consumed a standard diet of 11.2 MJ day(-1) (58% carbohydrate, 30% fat, 12% Protein) along with a high-protein supplement of 1.7 MJ day(-1) (40% carbohydrate, 35% protein, 25% fat) and 1.7 MJ day(-1) composed of 50% valine, 35% leucine, and 15% isoleucine. CON was given a standard diet of 14.5 MJ day(-1) (58% carbohydrate, 30% fat and 12% protein). During the race, heart rate was monitored. Subjects self-evaluated their feeling of fatigue every 3 h, and 12 samples of saliva from each subject were collected to perform cortisol assays. Before and after the race a vertical jump and a handgrip test were performed, and mental performance was evaluated with a standardized battery of tests. A significant increase in the feeling of fatigue was noted on the second day (D2) of race in both groups; the increase was higher in CON (P < 0.05). For both groups, salivary cortisol concentration followed a nycthemeral rhythm, with an alteration during the race as evidenced by high midnight cortisol levels between D1 and D2, and significantly decreased cortisol levels observed on D2 (P < 0.05). There was no change in physical performance at the end of the race in both groups. As a significant decrease (P < 0.05) in short-term memory performance was observed only in the CON group. These data indicate that an offshore sailing race enhances the feeling of fatigue, and decreases short-term memory performance. These detrimental consequences are reduced by a high-protein diet with BCAA.

Nycthemeral rhythm of intraocular pressure in normal tension glaucoma

Abstract Purpose: To characterize the circadian variations of intraocular pressure (IOP) in the normal tension glaucoma (NTG). Methods: Fourteen patients with NTG were studied. The age range was from 45 to 87 years old. All patients underwent a complete ophthalmologic examination (including corneal thickness) and visual field (Humphrey type). Then, IOP measurements were hourly controlled by Tonopen TM*, during a 24 hour cycle associated with sleep monitoring. The sleep study included a polysomnography (to exclude a sleep apnoea syndrome) and was associated with 24 hour measurements of blood pressure and heart rate. The nycthemeral rhythm was defined according to the cosinor technique. Results: Sixty percent of the patients exhibited an absence of circadian rhythm of IOP among 24 hours. Twenty one percent of the patients had a nocturnal rise of IOP and 21% of the patients had a diurnal rise of IOP (&lt; 21 mmHg). A sleep apnoea syndrome was diagnosed in 71% of the patients, abnormal nocturnal dips of arterial pressure were present in 78%, a vasospastic syndrome was present in 41.6% with and 40% of the patients exhibited an systemic hypertension. Conclusions: In our study, most of the patients shown an absence of nycthemeral rhythm of IOP. In this population, a high prevalence of sleep apnoea syndrome, of abnormal nocturnal dips of blood pressure, and of vasospastic syndrome was found.