Diurnal and seasonal tree water storage was studied in three large Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) trees at the Wind River Canopy Crane Research site. Changes in water storage were based on measurements of sap flow and changes in stem volume and tissue water content at different heights in the stem and branches. We measured sap flow by two variants of the heat balance method (with internal heating in stems and external heating in branches), stem volume with electronic dendrometers, and tissue water content gravimetrically. Water storage was calculated from the differences in diurnal courses of sap flow at different heights and their integration. Old-growth Douglas-fir trees contained large amounts of free water: stem sapwood was the most important storage site, followed by stem phloem, branch sapwood, branch phloem and needles. There were significant time shifts (minutes to hours) between sap flow measured at different positions within the transport system (i.e., stem base to shoot tip), suggesting a highly elastic transport system. On selected fine days between late July and early October, when daily transpiration ranged from 150 to 300 liters, the quantity of stored water used daily ranged from 25 to 55 liters, i.e., about 20% of daily total sap flow. The greatest amount of this stored water came from the lower stem; however, proportionally more water was removed from the upper parts of the tree relative to their water storage capacity. In addition to lags in sap flow from one point in the hydrolic pathway to another, the withdrawal and replacement of stored water was reflected in changes in stem volume. When point-to-point lags in sap flow (minutes to hours near the top and stem base, respectively) were considered, there was a strong linear relationship between stem volume changes and transpiration. Volume changes of the whole tree were small (equivalent to 14% of the total daily use of stored water) indicating that most stored water came from the stem and from its inelastic (sapwood) tissues. Whole tree transpiration can be maintained with stored water for about a week, but it can be maintained with stored water from the upper crown alone for no more than a few hours.

• MeSH
• cirkadiánní rytmus fyziologie   MeSH
• Pseudotsuga fyziologie   MeSH
• roční období MeSH
• stonky rostlin fyziologie   MeSH
• stromy fyziologie   MeSH
• transpirace rostlin fyziologie   MeSH
• voda fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Názvy látek
• voda MeSH

The objectives of this study were to investigate: 1) whether there were morning-to-evening differences in short-term maximal performance and 2) the impact of prolonged and specific warm-up on short-term maximal performance diurnal variations in young basketball players. Fifteen basketball players of both sexes (Male = 8; Female = 7; age: 14.4 ± 0.46 yr; weight: 64.7 ± 7.1 kg; height: 175.2 ± 6.6 cm; BMI: 21.1 ± 1.9 kg/m2) completed the following short-term maximal performance tests: CMJ with and without arm swing, Lane Agility Drill, Zig-Zag agility test with and without the ball, Sprint 20 m with and without the ball with the passage at 5 and 10 m. All tests were performed after the 15-min standard warm-up procedure (with static stretching) and/or 25-min specific warm-up (with prolonged running and dynamic stretching) in the morning and evening. Vertical jumping tests and all change-of-direction speed tests (with and without a ball) with superior responses were achieved in the evening after standard warm-up among all participants (p < 0.05). In contrast, superior short-term maximal performance was observed in the morning after prolonged and specific warm-up protocol (p < 0.05). It was concluded that specific and prolonged warm-up protocols are suitable strategy to prevent diurnal variation in short-term maximal performance in young basketball players.

• Klíčová slova
• Basketball, diurnal effect, physical performance, team sport,
• MeSH
• basketbal * fyziologie   MeSH
• běh * fyziologie   MeSH
• cirkadiánní rytmus MeSH
• lidé MeSH
• mladiství MeSH
• sportovní výkon * fyziologie   MeSH
• strečink * MeSH
• Check Tag
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

Wetland plants actively provide oxygen for aerobic processes in submerged tissues and the rhizosphere. The novel concomitant assessment of diurnal dynamics of oxygen and carbon dioxide concentrations under field conditions tests the whole-system interactions in plant-internal gas exchange and regulation. Oxygen concentrations ([O2]) were monitored in-situ in central culm and rhizome pith cavities of common reed (Phragmites australis) using optical oxygen sensors. The corresponding carbon dioxide concentrations ([CO2]) were assessed via gas samples from the culms. Highly dynamic diurnal courses of [O2] were recorded, which started at 6.5-13 % in the morning, increased rapidly up to 22 % during midday and declined exponentially during the night. Internal [CO2] were high in the morning (1.55-17.5 %) and decreased (0.04-0.94 %) during the rapid increase of [O2] in the culms. The observed negative correlations between [O2] and [CO2] particularly describe the below ground relationship between plant-mediated oxygen supply and oxygen use by respiration and biogeochemical processes in the rhizosphere. Furthermore, the nocturnal declining slopes of [O2] in culms and rhizomes indicated a down-regulation of the demand for oxygen in the complete below ground plant-associated system. These findings emphasize the need for measurements of plant-internal gas exchange processes under field conditions because it considers the complex interactions in the oxic-anoxic interface.

• Klíčová slova
• Aeration, Phragmites australis, constructed wetland, in-situ field study, internal carbon dioxide, internal oxygen dynamics,
• Publikační typ
• časopisecké články MeSH

AIM: To determine whether the promoter polymorphism -203A>C of cholesterol-7α-hydroxylase encoding gene (CYP7A1) affects diurnal variation in CYP7A1 enzyme activity. METHODS: The study included 16 healthy male volunteers - 8 homozygous for -203A and 8 homozygous for the -203C allele of CYP7A1. Three 15-hour examinations (from 7am to 10pm) were carried out for each of the participants: after one-day treatment with cholestyramine; after one-day treatment with chenodeoxycholic acid (CDCA); and a control examination without any treatment. The plasma concentration of 7α-hydroxy-4-cholesten-3-one (C4), a marker of CYP7A1 activity, was determined in all the experiments at 90-min intervals. RESULTS: CYP7A1 activity was up-regulated after treatment with cholestyramine and suppressed after treatment with CDCA. There were no differences between -203A and -203C allele carriers in the response of enzyme activity to both drugs. In the control experiment, -203A allele carriers displayed diurnal variation in enzyme activity, whereas CYP7A1 activity did not change in -203C allele carriers. These results were confirmed by modeling the dynamics of C4 using polynomial regression. CONCLUSION: The promoter polymorphism of the CYP7A1 gene has a pronounced impact on diurnal variation in CYP7A1 activity.

• MeSH
• aktivace enzymů MeSH
• cholestenony krev   MeSH
• cholesterol-7-alfa-hydroxylasa genetika   metabolismus   MeSH
• cholesterol krev   MeSH
• cirkadiánní rytmus fyziologie   MeSH
• dospělí MeSH
• lidé MeSH
• plocha pod křivkou MeSH
• polymorfismus genetický * MeSH
• promotorové oblasti (genetika) MeSH
• upregulace MeSH
• žlučové kyseliny a soli biosyntéza   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 7 alpha-hydroxy-4-cholesten-3-one MeSH Prohlížeč
• cholestenony MeSH
• cholesterol-7-alfa-hydroxylasa MeSH
• cholesterol MeSH
• CYP7A1 protein, human MeSH Prohlížeč
• žlučové kyseliny a soli MeSH

The JIP test, based on fast chlorophyll fluorescence (ChlF) kinetics and derived parameters, is a dependable tool for studying photosynthetic efficiency under varying environmental conditions. We extracted additional information from the whole OJIP and the normalized variable fluorescence (Vt) transient curve using first and second-order derivatives to visualize and localize points of landmark events. To account for light-induced variations in the fluorescence transient, we present a time-adjusted JIP test approach in which the derivatives of the transient curve are used to determine the exact timing of the J and I steps instead of fixed time points. We compared the traditional JIP test method with the time-adjusted method in analyzing fast ChlF measurements of silver birch (Betula pendula) in field conditions studying diurnal and within-crown variation. The time-adjusted JIP test method showed potential for studying ChlF dynamics, as it takes into account potential time shifts in the occurrence of J and I steps. The exact occurrence times of J and I steps and other landmark events coincided with the times of significant differences in fluorescence intensity. Chlorophyll fluorescence parameters were linearly related to photosynthetic photon flux density (PPFD) at different times of day, and the values obtained by the time-adjusted JIP test showed a stronger linear regression than the traditional JIP test. For fluorescence parameters having significant differences among different times of day and crown layers, the time-adjusted JIP test resulted in more clear differences than the traditional JIP test. Diurnal ChlF intensity data indicated that differences between the southern and northern provenance were only evident under low light conditions. Taken together, our results emphasize the potential relevance of considering the time domain in the analysis of the fast ChlF induction.

• Klíčová slova
• Betula pendula, Chlorophyll fluorescence, Diurnal variation, JIP test, Photosynthesis, Within-tree variation,
• MeSH
• bříza * MeSH
• chlorofyl MeSH
• fluorescence MeSH
• fotosyntéza MeSH
• listy rostlin MeSH
• stromy * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chlorofyl MeSH

It has been suggested that atmospheric CO2 concentration and frequency of cloud cover will increase in future. It remains unclear, however, how elevated CO2 influences photosynthesis under complex clear versus cloudy sky conditions. Accordingly, diurnal changes in photosynthetic responses among beech trees grown at ambient (AC) and doubled (EC) CO2 concentrations were studied under contrasting sky conditions. EC stimulated the daily sum of fixed CO2 and light use efficiency under clear sky. Meanwhile, both these parameters were reduced under cloudy sky as compared with AC treatment. Reduction in photosynthesis rate under cloudy sky was particularly associated with EC-stimulated, xanthophyll-dependent thermal dissipation of absorbed light energy. Under clear sky, a pronounced afternoon depression of CO2 assimilation rate was found in sun-adapted leaves under EC compared with AC conditions. This was caused in particular by stomata closure mediated by vapour pressure deficit.

• Klíčová slova
• DEPS, Diurnal dynamics, European beech, Fluorescence, Photorespiration, Stomatal conductance, Xanthophylls,
• MeSH
• biologické modely MeSH
• buk (rod) fyziologie   MeSH
• fotosyntéza fyziologie   MeSH
• látky znečišťující vzduch metabolismus   MeSH
• listy rostlin fyziologie   MeSH
• oxid uhličitý metabolismus   MeSH
• počasí * MeSH
• světlo MeSH
• xanthofyly metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• látky znečišťující vzduch MeSH
• oxid uhličitý MeSH
• xanthofyly MeSH

BACKGROUND: The patients with rheumatoid arthritis have high prevalence of hypertension and increased risk of cardiovascular morbidity and mortality. OBJECTIVE: To determine the level of clinical blood pressure (BP) and 24h ambulatory BP in patients with rheumatoid arthritis and hypertension. Analyze the diurnal variability of BP depending on chronic treatment with prednisone, nonsteroidal anti-inflammatory drugs and methotrexate. GROUP OF PATIENTS: 60 patients with clinically stable rheumatoid arthritis and treated or newly diagnosed hypertension. 15 male and 45 female, mean age 58 +/- 11.3 years. RESULTS: Mean clinical systolic BP 139.0 +/- 14.7 mm Hg, diastolic BP 85.7 +/- 6.5 mm Hg and heart rate 74.9 +/- 7.3 beat.min(-1). Mean 24h systolic BP 127.7 +/- 12.6 mm Hg, diastolic BP 77.7 +/- 7.4 mm Hg and heart rate 73.9 +/- 8.7 beat.min(-1). Mean clinical pulse pressure 54.7 +/- 15.6 mm Hg, mean 24h pulse pressure 50.1 +/- 11.6 mm Hg. In the whole group of patients the number of systolic dippers was 28 (47%), nondippers 17 (28%), excesive dippers 11 (18%) and risers 4 (7%), diastolic dippers 27 (45%), nondippers 9 (15%), excesive dippers 22 (37%) and risers 2 (3%). The patients treated with prednisone and nonsteroidal anti-inflammatory drugs were nondippers in 34% both for systolic BP, in 19% and 20% respectively for diastolic BP. They were excessive dippers for systolic BP in 22% and 20% respectively, for diastolic BP in 37% and 38% respectively. In the course of the treatment with methotrexate were 22% patients nondippers for systolic BP and 8% for diastolic BP, 28% was excessive dippers for systolic BP, 47% for diastolic BP. CONCLUSION: Patients with rheumatoid arthritis and hypertension have a slightly increased pulse pressure (55 mm Hg for clinical BP and 50 mm Hg for 24h ambulatory BP) in comparison to arbitrary limits in generally population. Patients treated with prednison and nonsteroidal anti-inflammatory drugs were more often nondippers (34%) in systolic BP than hypertensive control. The patients treated with methotrexate (47%), prednisone (37%) and nonsteroidal anti-inflammatory drugs (38%) were more often excessive dippers in diastolic BP than hypertensive control.

• MeSH
• cirkadiánní rytmus * MeSH
• elektrokardiografie ambulantní MeSH
• hypertenze komplikace   patofyziologie   MeSH
• krevní tlak fyziologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• revmatoidní artritida komplikace   farmakoterapie   patofyziologie   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH

We conducted year-long measurements of the photochemical reflectance index (PRI) and solar-induced fluorescence in the O2A oxygen band (SIFA) at a Norway spruce forest and a European beech forest to study relationships of these remote sensing variables to photosynthesis by trees in grown forest stands. Measured PRI and SIFA values were linked to changes in forest gross primary productivity (GPP) and light-use efficiency (LUE). Changes in the shadow fraction (αS) within tree crowns influenced PRI and fluorescence signals. In the spruce forest, the quantum yield of SIFA (FYSIFA) decreased around midday together with photosynthesis and GPP. Such decreases in FYSIFA were accompanied by an increase in the αS. In the beech forest, we detected an increase in FYSIFA together with a decrease in αS in the afternoon hours. The overall sensitivity of PRI to LUE was variable according to the season, presumably influenced by complex changes in photosynthetic pigments. PRI and FYSIFA showed weak correlations with canopy LUE; however, when considered together, the correlation was strengthened (R2 was 0.63 and 0.34 in spruce and beech forest, respectively). Our model predicting LUE dynamics includes a diurnal minimum of PRI and canopy αS to make allowances for seasonal changes in photosynthetic pigments and for diurnal variability of the shadow fraction in forests. The incorporation of these correcting factors allowed us to estimate LUE at R2 = 0.68 (spruce) and 0.53 (beech). The modeling equations appeared sensitive to the absorbed photosynthetically active radiation (APAR), but less sensitive to the GPP of these forests. Substituting pigments correction with introducing differential PRI (ΔPRI) into the model did not significantly improve the LUE estimation across the season. Our results show that the joint use of PRI and fluorescence improves LUE and GPP estimation accuracy in both daily and seasonal observations.

• Klíčová slova
• 3-FLD, Daily dynamics, Fluorescence, LiDAR, Photochemical reflectance index, Shadow fraction,
• MeSH
• buk (rod) * MeSH
• fotosyntéza MeSH
• lesy MeSH
• roční období MeSH
• sluneční záření MeSH
• smrk * MeSH
• stromy MeSH
• Publikační typ
• časopisecké články MeSH

Microbial activity in forest soils is driven by the dynamics of ecosystem processes, largely dependent on trees as the major primary producers. Diurnal variation of root activity, seasonality of photosynthate production or recalcitrance of decomposing plant biomass all affect microbial abundance, composition of their communities and activity. Due to low N content, fungi appear to be the major decomposers of complex plant biomass: litter and deadwood and to largely shape associated bacterial communities and their activity. On the other hand, bacteria are important in decomposition of fungal mycelia and N-cycle processes including N-fixation. Microbial activity is also affected in the short term by climatic events and in the long-term by ecosystem development after disturbances.

• MeSH
• Bacteria klasifikace   růst a vývoj   metabolismus   MeSH
• houby klasifikace   růst a vývoj   metabolismus   MeSH
• koloběh dusíku MeSH
• lesy * MeSH
• podnebí MeSH
• půdní mikrobiologie * MeSH
• roční období MeSH
• společenstvo * MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

These experiments aim to reveal the dynamic features that occur during the metabolism of the unicellular, nitrogen fixing cyanobacterium Cyanothece sp. when exposed to diverse circadian forcing patterns (LD 16:8, LD 12:12, LD 8:16, LD 6:6). The chlorophyll concentration grew rapidly from subjective morning when first illuminated to around noon, then remained stable from later in the afternoon and throughout the night. The optical density measured at 735 nm was stable during the morning chlorophyll accumulation, then increased in the early afternoon toward a peak, followed at dusk by a rapid decline toward the late night steady state. The authors propose that these dynamics largely reflect accumulation and subsequent consumption of glycogen granules. This hypothesis is consistent with the sharp peak of respiration that coincides with the putative hydrocarbon catabolism. In the long-day regimen (LD 16:8), these events may mark the transition from the aerobic photosynthetic metabolism to microaerobic nitrogen metabolism that occurs at dusk, and thus cannot be triggered by the darkness that comes later. Rather, control is likely to originate in the circadian clock signaling an approaching night. To explore the dynamics of the link between respiration and circadian oscillations, the authors extrapolated an earlier model of the KaiABC oscillator from Synechococcus elongatus to Cyanothece sp. The measured peak of respiratory activity at dusk correlated strongly in its timing and time width with the modeled peak in accumulation of the KaiB(4) complex, which marks the late afternoon phase of the circadian clock. The authors propose a hypothesis that high levels of KaiB(4) (or of its Cyanothece sp. analog) trigger the glycogen catabolism that is reflected in the experiments in the respiratory peak. The degree of the correlation between the modeled KaiB(4) dynamics and the dynamics of experimentally measured peaks of respiratory activity was further tested during the half-circadian regimen (LD 6:6). The model predicted an irregular pattern of the KaiABC oscillator, quite unlike mechanical or electrical clock pacemakers that are strongly damped when driven at double their endogenous frequency. This highly unusual dynamic pattern was confirmed experimentally, supporting strongly the validity of the circadian model and of the proposed direct link to respiration.

• MeSH
• biologické hodiny fyziologie   MeSH
• biologické modely * MeSH
• cirkadiánní rytmus fyziologie   MeSH
• Cyanothece růst a vývoj   metabolismus   účinky záření   MeSH
• fotoperioda MeSH
• kyslík metabolismus   MeSH
• oxid uhličitý metabolismus   MeSH
• počítačová simulace MeSH
• světlo MeSH
• tma MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kyslík MeSH
• oxid uhličitý MeSH