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Diurnal Pattern (diurnal + pattern)
Selected AbstractsStrategies providing success in a variable habitat: III.PLANT CELL & ENVIRONMENT, Issue 8 2001Dynamic control of photosynthesis in Cladophora glomerata Abstract Diurnal patterns of photosynthesis were studied in July and April populations of Cladophora glomerata (L.) Kütz. from open and from shaded sites. Summer samples exposed to full sunlight showed decreased efficiency of open photosystem II at noon, and only slight differences were found between samples that had grown at open or at shaded sites. Electron transport rate was limited at highest fluence rates in shade plants, and non-photochemical quenching (NPQ) revealed faster regulation in samples from open sites. Daily course of de-epoxidation was not linearly correlated with the course of NPQ. The comparison of samples from open and from shaded sites revealed a higher capacity of thermal energy dissipation and an increase in the total amount of xanthophyll-cycle pigments (21%) in samples from open sites. In April, down-regulation of the efficiency of open photosystem II was related to lower water temperature, and hence, increased excitation pressure. In April the pool size of xanthophyll-cycle pigments was increased by 21% in comparison with summer and suggested higher levels of thermal energy dissipation via de-epoxidized xanthophylls. In both, summer and spring the amount of xanthophyll-cycle pigments was 20% higher in samples from open sites. Acclimation of C. glomerata to growth light conditions was further shown by experimental induction of NPQ, indicating NPQ increases of 23%, and increases of 77% in the reversible component of NPQ in open site samples. The effect of temperature on photosynthetic rate was non-linear, and different optimum temperatures of electron transport rate and oxygen evolution were exhibited. [source] PRECLINICAL STUDY: Circadian regulation of central ethanol sensitivity by the mPer2 geneADDICTION BIOLOGY, Issue 3 2009Stéphanie Perreau-Lenz ABSTRACT The effect of alcohol is known to vary with the time of the day. Although initially it was suggested that this phenomenon may be due to diurnal differences in ethanol metabolism, more recent studies were contradicting. In the present study, we therefore first set out in assessing the diurnal variations in ethanol sensitivity in mice analysing, concurrently, ethanol elimination rates. Ethanol-induced (3.5 g/kg; intraperitoneal) loss of righting reflex (LORR) duration was thus determined at several Zeitgeber time (ZT) points (ZT5, 11, 17 and 23) in C57BL/6N mice. In parallel, the corresponding ethanol elimination rates were also assessed. The results display the existence of a distinct diurnal rhythm in LORR duration peaking at ZT11, whereas no differences could be observed regarding the elimination rates of alcohol. Successively, we checked the involvement of the clock genes mPer1 and mPer2 in conveying this rhythm in sensitivity, testing LORR and hypothermia at the peak and trough previously observed (ZT5 and ZT11). Per1Brdm1 mice demonstrate a similar diurnal pattern as control mice, with enhanced LORR durations at ZT11. In contrast, Per2Brdm1 mice did not exhibit a temporal variation to the depressant effects of ethanol with respect to LORR, revealing a constant high sensitivity to ethanol. The present study reveals a central role of the mPer2 gene in inhibiting alcohol sensitivity at the beginning of the inactive phase. [source] Fine-scale movements of the swordfish Xiphias gladius in the Southern California BightFISHERIES OCEANOGRAPHY, Issue 4 2010CHUGEY A. SEPULVEDA Abstract This study reports on the fine-scale movements of swordfish (Xiphias gladius) outfitted with pop-off satellite archival transmitters (PSATs) in the Southern California Bight (SCB). PSATs were deployed on basking swordfish using traditional harpoon methods from 2004 to 2006. Transmitters were programmed for short-term deployment (2,90 days) and re-acquired using a signal direction finder. High-resolution (min,1) depth and temperature data from nine swordfish (approximately 45,120 kg) were collected (>193 days). All swordfish displayed diurnal vertical movements similar to those reported for other geographic locations. The dominant diurnal movement pattern entailed swordfish remaining below the thermocline (>68 ± 15 m) during the day and near the surface, within the upper-mixed layer, at night. Collectively, the average daytime depth (±SE) was 273 ± 11 m and the average night depth 31 ± 5 m. Three distinct vertical behaviors were recorded: 35% of the records following a strict diurnal pattern, with the entire day below the thermocline and the entire night near the surface; 52% of the records revealed routine surface-basking events during the day, with an otherwise similar distribution at night; and 13% of the records exhibited surface-oriented activity during the day and night. Surface basking (<3 m during the day) was recorded for eight individuals and occurred on 131 of the 193 days (68% of the dataset). Collectively, surface basking accounted for 8% of the total daytime records. The relevance of these vertical behaviors to SCB fisheries is discussed. [source] Thermal habitat experienced by Atlantic salmon (Salmo salar L.) kelts in coastal Newfoundland watersFISHERIES OCEANOGRAPHY, Issue 1 2004David G. Reddin Abstract Thermal habitat was recorded by data storage tags (DSTs) applied to Atlantic salmon (Salmo salar L.) kelts during their seaward migration in the spring of 1998 at enumeration facilities in Highlands River, Humber River, Western Arm Brook, and Campbellton River, Newfoundland. In total, 139 DSTs were applied and data were downloaded from eleven of the recovered tags. The recovered tags had been applied at Highlands, Campbellton and Western Arm rivers and recovered in the coastal waters of Newfoundland and Québec and at the enumeration facilities at Highlands and Campbellton rivers. Water temperatures experienced by the fish were recorded for periods of 62,118 days at resolutions of 15,30 min. The data from the sea record on the DSTs were analysed for temperature patterns in relation to migration behaviour and diurnal movement of the fish. A variety of patterns were exhibited on the temperature records suggesting that the fish were behaving in various ways at different times. For Campbellton and Highlands fish over the course of some 24 h periods, night-time temperatures changed little and were among the highest daily temperatures experienced by the fish, whereas daytime temperatures often showed dramatic and frequent shifts in temperature presumably as the fish rapidly and frequently changed depth. For the Western Arm Brook fish, rapid fluctuations in temperature occurred sometimes during the day and night without a consistent diurnal pattern. We also considered large-scale aspects of the data by examining oceanographic conditions in relation to the temperatures recorded by the tags. [source] Temporal, spatial and biotic variations in extrafloral nectar secretion by Macaranga tanariusFUNCTIONAL ECOLOGY, Issue 6 2000Heil M. Abstract 1Many plants produce extrafloral nectar (EFN) to nourish ants and other animals which defend them against herbivores. We aimed to find reasons for the high variability in amounts of EFN produced by most plant species. We investigated the influence of several biotic and abiotic factors (time of day, leaf age, nectar removal and leaf damage) on secretion rates of EFN in the common south-east Asian pioneer tree species, Macarangatanarius (L.) Muell. Arg. 2In most experiments leaves were washed with pure water and bagged in nets to protect them against nectar-collecting insects, and nectar was collected and quantified 24 h later. Six soluble sugars and up to eight amino acids were detected in nectar samples derived from untreated, field-grown plants. Total amounts of soluble substances varied more than the relative composition of EFN. 3Nectar secretion rates were highest on young, expanded leaves. A diurnal pattern with a secretion peak in the first 2 h after dusk was detected in the field. Nectar removal had a positive effect and its accumulation a negative effect on further EFN production. Artificial leaf damage (punching leaves with a needle or removing parts of the leaf blade with scissors) led to a significant induction of EFN production for the next 3 days. 4Extrafloral nectar of M. tanarius was secreted in complex patterns influenced by different biotic and abiotic factors; its production appeared to be adapted temporally and spatially in order to ensure optimal use of invested resources. [source] Water table fluctuations under three riparian land covers, Iowa (USA)HYDROLOGICAL PROCESSES, Issue 18 2007Keith E. Schilling Abstract Water table depth is known to play an important role in nitrogen cycling in riparian zones, but little detailed monitoring of water table fluctuations has been reported. In this study, results of high-resolution water table monitoring under three common riparian land covers (forest, cool season grass, corn) were analysed to gain a better understanding of the relation of vegetation cover to water table depth. Three riparian wells located at the Neal Smith National Wildlife Refuge in Jasper County, Iowa, were instrumented with data loggers to record hourly water table behaviour from July to December 2004. Water table depth under the forest showed a diurnal pattern of rising and falling water levels, whereas the grass and corn exhibited a stepped pattern of greater drawdown during the day and less drainage at night. Clear daytime and night-time water table signals were related to daily plant water demands and lateral groundwater flow. Using two estimates of specific yield, hourly and daily ET rates were estimated to be higher under the forest cover than the grass and corn, with peak ET rates in July ranging from 5·02 to 6·32 mm day,1 for forest and from 1·81 to 4·13 mm day,1 for corn and grass. Following plant senescence in October, water table declines were associated with lateral flow to Walnut Creek. The results from this study suggest that consideration should be given to monitoring water table behaviour more frequently to capture daily and seasonal patterns related to riparian vegetation type. Copyright © 2007 John Wiley & Sons, Ltd. [source] The Associations Between Basal Salivary Cortisol and Illness Symptomatology in Chronic Fatigue SyndromeJOURNAL OF APPLIED BIOBEHAVIORAL RESEARCH, Issue 3 2008Susan Torres-Harding Hypocortisolism has been reported in chronic fatigue syndrome (CFS), with the significance of this finding to disease etiology unclear. This study examined cortisol levels and their relationships with symptoms in a group of 108 individuals with CFS. CFS symptoms examined included fatigue, pain, sleep difficulties, neurocognitive functioning, and psychiatric status. Alterations in cortisol levels were examined by calculation of mean daily cortisol, and temporal variation in cortisol function was examined by means of a regression slope. Additionally, deviation from expected cortisol diurnal pattern was determined via clinical judgment. Results indicated that fatigue and pain were associated with salivary cortisol levels. In particular, variance from the expected pattern of cortisol was associated with increased levels of fatigue. The implications of these findings are discussed. [source] Case of combined adrenal cortical adenoma and myelolipomaPATHOLOGY INTERNATIONAL, Issue 9 2004Takaharu Matsuda We report a case of myelolipoma 10 mm in size within a functional cortical adenoma that was 33 × 22 × 17 mm in size. A 29-year-old woman was referred to hospital for transient hypertension. A right adrenal tumor was detected by computed tomography (CT) scan and magnetic resonance imaging (MRI). Her cortisol levels indicated a loss of the normal diurnal pattern, and urinary 17-hydroxycorticosteroids was elevated. She underwent a right adrenalectomy under the diagnosis of adrenal adenoma with Cushing's syndrome. The tumor was fairly well encapsulated by a thin layer of connective tissue. The major tumor portion was composed of two distinct cell types, clear cells and eosinophilic cells, arranged in an alveolar structure. These findings were representative of cortical adenoma. The adrenal cortical adenoma centrally included well-demarcated adipose tissue admixed with scattered islands of myelopoietic elements: erythroblasts, myeloid cell series and lymphocytic cells, which was eventually recognized as myelolipoma. Recently, adrenal myelolipoma has commonly been found because of the ease of detecting it as an incidentaloma by CT scan or MRI. However, the present adrenal myelolipoma case is uncommon because it is combined with a functioning cortical adenoma. Only six similar cases have previously been reported in English and Japanese publications. Furthermore, in the present case, the myelolipoma formed a tumor nodule, and to our knowledge, this is the first reported case of a radiographically recognizable tumor nodule. We discuss the etiology of myelolipoma and suggest that myelolipoma can develop in the course of endocrine hyperfunction. [source] Temporal pattern of feeding activity in the firebug Pyrrhocoris apterus and its relation to sex, wing dimorphism and physiological state of adultsPHYSIOLOGICAL ENTOMOLOGY, Issue 1 2007RADOMÍR SOCHA Abstract The present study tested whether the pattern of feeding activity in the firebug Pyrrhocoris apterus (L.) is sex- and wing morph-related, diurnal or nocturnal, as well as whether the feeding rhythm persists in constant darkness. Temporal patterns of feeding activity are analysed in macropterous and brachypterous adults reared under long-day (LD 18 : 6 h) and short-day (LD 12 : 12 h) photoperiods, and in adults transferred to constant darkness. In females, the total feeding activity is highest in long-day reproductively active brachypters, intermediate in short-day diapausing brachypters, and lowest in macropters; the differences among males are substantially smaller. Although the total feeding activity of macropterous males is higher than in macropterous females, no sex-related differences are found in feeding activity of diapausing and reproductively active brachypters. The frequency of feeding exhibits sex-related differences, with obviously higher values in males. Mean feeding periods of macropterous and reproductively active brachypterous males are shorter than in females of the same wing morph. Mean interfeeding periods are longest in macropters, intermediate in diapausing brachypters, and shortest in reproductively active brachypters, and always lower in males than in females. The study shows that the feeding activity of P. apterus adults is age-, sex- and wing morph-related, and exhibits a diurnal pattern, except in reproductively active brachypterous females. The latter do not express a clear diurnal rhythm of feeding, presumably because of interactions with cycles of egg development and oviposition. The persistence of diurnal rhythm of feeding activity in short-day brachypterous females transferred to constant darkness indicates an endogeneity of this rhythm in P. apterus. [source] The neurochemistry of waking and sleeping mental activity: The disinhibition-dopamine hypothesisPSYCHIATRY AND CLINICAL NEUROSCIENCES, Issue 4 2002CLAUDE GOTTESMANN Abstract This paper describes a hypothesis related to the neurochemical background of sleep-waking mental activity which, although associated with subcortical structures, is principally generated in the cerebral cortex. Acetylcholine, which mainly activates cortical neurons, is released at the maximal rate during waking and rapid eye movement (REM) sleep dreaming stage. Its importance in mental functioning is well-known. However, brainstem-generated monoamines, which mainly inhibit cortical neurons, are released during waking. Both kinds of influences contribute to the organized mentation of waking. During slow wave sleep, these two types of influence decrease in intensity but maintain a sufficiently high level to allow mental activity involving fairly abstract pseudo-thoughts, a mode of activity modelled on the diurnal pattern of which it is a poor reply. During REM sleep, the monoaminergic neurons become silent except for the dopaminergic ones. This results in a large disinhibition and the maintained dopamine influence may be involved in the familiar psychotic-like mental activity of dreaming. Indeed, in this original activation,disinhibition state, the increase of dopamine influence at the prefrontal cortex level could explain the almost total absence of negative symptoms of schizophrenia during dreaming, while an increase in the nucleus accumbens is possibly responsible for hallucinations and delusions, which are regular features of mentation during this sleep stage. [source] Intermittent hypoxia reverses the diurnal glucose rhythm and causes pancreatic ,-cell replication in miceTHE JOURNAL OF PHYSIOLOGY, Issue 3 2008Takuya Yokoe Obstructive sleep apnoea (OSA) and type 2 diabetes frequently co-exist and potentially interact haemodynamically and metabolically. However, the confounding effects of obesity have obscured the examination of any independent or interactive effects of the hypoxic stress of OSA and the hyperglycaemia of type 2 diabetes on haemodynamic and metabolic outcomes. We have developed a chronically catheterized, unhandled, lean murine model to examine the effects of intermittent hypoxic (IH) exposure and exogenous glucose infusion on the diurnal pattern of arterial blood pressure and blood glucose, as well as pancreatic ,-cell growth and function. Four experimental groups of adult male C57BL/J mice were exposed to 80 h of (1) either IH (nadir of inspired oxygen 5,6% at 60 cycles h,1 for 12 h during light period) or intermittent air (IA; control) and (2) continuous infusion of either 50% dextrose or saline (control). IH exposure during saline infusion caused a sustained increase in arterial blood pressure of 10 mmHg (P < 0.0001), reversed the normal diurnal rhythm of blood glucose (P < 0.03), doubled corticosterone levels (P < 0.0001), and increased replication of pancreatic ,-cells from 1.5 ± 0.3 to 4.0 ± 0.8% bromodeoxyuridine (BrdU)-positive) ,-cells. The combined stimulus of IH exposure and glucose infusion attenuated the hypertension, exacerbated the reversed diurnal glucose rhythm, and produced the highest rates of apoptosis in ,-cells, without any additive effects on ,-cell replication. We conclude that, in contrast to the development of sustained hypertension, IH impaired glucose homeostasis only during periods of hypoxic exposure. IH acted as a stimulus to pancreatic ,-cell replication, but the presence of hyperglycaemia may increase the hypoxic susceptibility of ,-cells. This model will provide a basis for future mechanistic studies as well as assessing the metabolic impact of common comorbities in OSA, including obesity, insulin resistance and type 2 diabetes. [source] Circadian rhythm of stroke onset during the month of RamadanACTA NEUROLOGICA SCANDINAVICA, Issue 2 2010A. El-Mitwalli El-Mitwalli A, Zaher AA, El Menshawi E. Circadian rhythm of stroke onset during the month of Ramadan. Acta Neurol Scand: 2010: 122: 97,101. © 2009 The Authors Journal compilation © 2009 Blackwell Munksgaard. Background and purpose,,, The onset of acute stroke exhibits a circadian pattern occurring more frequently in late morning hours. The objective of this study was to investigate the diurnal pattern of stroke during the month of Ramadan. Patients and methods,,, We studied consecutive stroke patients 1 month before Ramadan (BR) and during Ramadan (DR) over two successive years 2007 and 2008. The age, gender, risk factor profiles were analyzed. The National Institute of Health and Stroke Scale Score (NIHSS) was used for clinical assessment at admission. The exact time of stroke onset in both groups was obtained. Results,,, A total of 507 patients were studied: 245 patients in the DR group and 262 patients in the BR group. The age distribution of patients was not significantly different between the two groups. There was no statistically significant difference in the sex ratio, risk factors, and NIHSS score between the two groups (P > 0.05). The higher frequency of stroke onset time in the BR group was in the time between 6:00 a.m. and noon; whereas the frequency was higher between noon and 6:00 p.m. in the DR group. Conclusion,,, A significant shift of the circadian pattern of stroke onset time from the period between 6:00 a.m. and noon to that between noon and 6:00 pm has been found during the month of Ramadan. [source] Temporal distribution of clinical seizures over the 24-h day: A retrospective observational study in a tertiary epilepsy clinicEPILEPSIA, Issue 9 2009Wytske A. Hofstra Summary Purpose:, Very few studies have evaluated seizure occurrence in humans over the 24-h day; data from children are particularly scarce. Circadian patterns in seizure occurrence may be of importance in epilepsy research and may have important implications in diagnosis and therapy. Methods:, We have analyzed clinical seizures of 176 consecutive patients (76 children, 100 adults) who had continuous electroencephalography (EEG) and video monitoring lasting more than 22 h. Several aspects of seizures were noted, including classification, time of day, origin, and sleep stage. Results:, More than 800 seizures were recorded. Significantly more seizures were observed from 11:00 to 17:00 h, and from 23:00 to 05:00 h significantly fewer seizures were seen. The daytime peak incidences were observed in seizures overall, complex partial seizures (in children and adults), seizures of extratemporal origin (in children), and seizures of temporal origin (in adults). Incidences significantly lower than expected were seen in the period 23:00 to 05:00 h in seizures overall, complex partial seizures (in children and adults), and in tonic seizures (in children). In addition, significantly fewer seizures of temporal (in children and adults) and extratemporal origin (in children) were observed in this period. Discussion:, The results suggest that certain types of seizures have a strong tendency to occur in true diurnal patterns. These patterns are characterized by a peak during midday and a low in the early night. [source] Assessing the sources and magnitude of diurnal nitrate variability in the San Joaquin River (California) with an in situ optical nitrate sensor and dual nitrate isotopesFRESHWATER BIOLOGY, Issue 2 2009BRIAN A. PELLERIN Summary 1.,We investigated diurnal nitrate (NO3,) concentration variability in the San Joaquin River using an in situ optical NO3, sensor and discrete sampling during a 5-day summer period characterized by high algal productivity. Dual NO3, isotopes (,15NNO3 and ,18ONO3) and dissolved oxygen isotopes (,18ODO) were measured over 2 days to assess NO3, sources and biogeochemical controls over diurnal time-scales. 2.,Concerted temporal patterns of dissolved oxygen (DO) concentrations and ,18ODO were consistent with photosynthesis, respiration and atmospheric O2 exchange, providing evidence of diurnal biological processes independent of river discharge. 3.,Surface water NO3, concentrations varied by up to 22% over a single diurnal cycle and up to 31% over the 5-day study, but did not reveal concerted diurnal patterns at a frequency comparable to DO concentrations. The decoupling of ,15NNO3 and ,18ONO3 isotopes suggests that algal assimilation and denitrification are not major processes controlling diurnal NO3, variability in the San Joaquin River during the study. The lack of a clear explanation for NO3, variability likely reflects a combination of riverine biological processes and time-varying physical transport of NO3, from upstream agricultural drains to the mainstem San Joaquin River. 4.,The application of an in situ optical NO3, sensor along with discrete samples provides a view into the fine temporal structure of hydrochemical data and may allow for greater accuracy in pollution assessment. [source] Nocturnal fish utilization of a subtropical mangrove-seagrass ecotoneMARINE ECOLOGY, Issue 2 2010Neil Hammerschlag Abstract Whereas diel fish migration between mangrove and seagrass habitats has been recognized for decades, quantitative studies have focused mainly on diurnal patterns of fish distribution and abundance. In general, previous studies have shown that fish abundances decline with increasing distance from mangroves; however, evidence for such a pattern at night, when many fishes are actively feeding, is scarce. The present study is the first to report nocturnal fish abundances along a continuous distance gradient from mangroves across adjacent seagrass habitat (0,120 m). Here, we used nocturnal seine sampling to test the null hypothesis (based on diurnal studies and limited nocturnal work) that fish abundance would decrease with increasing distance from shoreline. We focused on species and life-stage-specific abundance patterns of Lutjanus griseus, Sphyraena barracuda, Archosargus rhomboidalis, and Haemulon sciurus. Results indicated that assemblage composition and structure differed significantly by season, likely influenced by temperature. However, within each season, the fish habitat use pattern at both the assemblage and species-specific level generally failed to support our working null hypothesis. Species-specific analyses revealed that, for most species and life-stages examined, nocturnal abundance either did not change with distance or increased with distance from the mangrove-seagrass ecotone. Our results suggest that analyses where taxa are grouped to report overall patterns may have the potential to overlook significant species- and stage-specific variation. For fishes known to make nocturnal migrations, we recommend nocturnal sampling to determine habitat utilization patterns, especially when inferring nursery value of multiple habitats or when estimating fish production. [source] Spatial and temporal partitioning of behaviour by adult dacines: direct evidence for methyl eugenol as a mate rendezvous cue for Bactrocera cacuminataPHYSIOLOGICAL ENTOMOLOGY, Issue 3 2003S. Raghu Abstract., Resource use in adult Dacinae (Diptera: Tephritidae) is believed to be restricted to the host plant (i.e. the plant that provides fruit for oviposition and larval development). However, studies on Bactrocera cacuminata did not support this hypothesis. Thus, it was hypothesized that adult flies partition their diurnal activities between spatially separated resources (host plant, sugar, protein and methyl eugenol) as a function of the physiological status of the fly (immature, mature,unmated, mature,mated). In accordance with a priori predictions, the results of a field-cage study show that there are significant diurnal patterns in abundance and behaviour, and that flies of different physiological status use resources differently. Immature flies spend most of their time foraging for sugar and protein to facilitate development. Sexually mature flies forage for sugars during the day, and at dusk, responded strongly to methyl eugenol and mate. The fact that polygynous males wait at methyl eugenol at dusk whereas the mated, monandrous females spend their time ovipositing in fruit and are nonresponsive to methyl eugenol, supports Metcalf's hypothesis that such phenylpropanoids serve as mate rendezvous cues. [source] | |||||||||||||