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8122. Exceptional photosynthetic performance of Capparis spinosa L. under adverse conditions of Mediterranean summer
- Creator:
- Levizou, E., Drilias, P., and Kyparissis, A.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll fluorescence, daily and seasonal photosynthesis;, net photosynthetic rate, stomatal conductance, summer perennial, transpiration rate, and water potential
- Language:
- Multiple languages
- Description:
- Diurnal and seasonal fluctuations in water potential (Ψ), stomatal conductance (gs), transpiration rate (E), and net photosynthetic rate (PN) were monitored in Capparis spinosa L., a Mediterranean plant growing during summer, i.e. at the period considered the most stressful for local plant life. In spite of the complete absence of rain, Ψ exhibited a modest drop at midday (-2.7 MPa), but was fully recovered overnight, indicating sufficient access to water sources. The stomata remained open throughout the day and season and the high E resulted in leaf temperatures up to 3.9 °C below air temperature. Additionally, PN of the fully exposed leaves was higher than 25 μmol m-2 s-1 for more than 10 h per day throughout the summer growth period. No symptoms of photooxidative stress were shown, as judged by maximum photosystem 2 photochemical efficiency (Fv/Fm) and the function of xanthophyll cycle. Indeed, diurnal inter-conversions of the xanthophyll cycle components were modest during the summer and a more intensive function of the cycle was only evident during leaf senescence in autumn. In comparison with a semi-deciduous and an evergreen sclerophyll co-existing in the same ecosystem, C. spinosa assimilated up to 3.4 times more CO2 per m2 during its growth period (May to October) and up to 1.8 times more on an annual basis. and E. Levizou, P. Drilias, A. Kyparissis.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
8123. Excess irradiance causes early symptoms of senescence during leaf expansion in photoautotrophically in vitro grown tobacco plants
- Creator:
- Radochová, B. and Tichá, I.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll a fluorescence, leaf area, leaf dry mass, leaf ontogeny, net oxygen evolution rate, Nicotiana, and photosynthesis
- Language:
- Multiple languages
- Description:
- Photosynthetic parameters, growth, and pigment contents were determined during expansion of the fourth leaf of in vitro photoautotrophically cultured Nicotiana tabacum L. plants at three irradiances [photosynthetically active radiation (400-700 nm): low, LI 60 µmol m-2 s-1; middle, MI 180 µmol m-2 s-1; and high, HI 270 µmol m-2 s-1]. During leaf expansion, several symptoms usually accompanying leaf senescence appeared very early in HI and then in MI plants. Symptoms of senescence in developing leaves were: decreasing chlorophyll (Chl) a+b content and Chl a/b ratio, decreasing both maximum (FV/FM) and actual (ΦPS2) photochemical efficiency of photosystem 2, and increasing non-photochemical quenching. Nevertheless, net photosynthetic oxygen evolution rate (PN) did not decrease consistently with decrease in Chl content, but exhibited a typical ontogenetic course with gradual increase. PN reached its maximum before full leaf expansion and then tended to decline. Thus excess irradiance during in vitro cultivation did not cause early start of leaf senescence, but impaired photosynthetic performance and Chl content in leaves and changed their typical ontogenetic course. and B. Radochová, I. Tichá.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
8124. Excess of free fatty acids as a cause of metabolic dysfunction in skeletal muscle
- Creator:
- Jana Tůmová, Michal Anděl, and Jan Trnka
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, obezita, inzulinová rezistence, obesity, insulin resistance, free fatty acids, skeletal muscle, mitochondrial function, 14, and 612
- Language:
- English
- Description:
- Obesity is often associated with metabolic impairments in peripheral tissues. Evidence suggests an excess of free fatty acids (FFA) as one factor linking obesity and related pathological conditions and the impact of FFA overload on skeletal muscle metabolism is described herein. Obesity is associated with dysfunctional adipose tissue unable to buffer the flux of dietary lipids. Resulting increased levels and fluxes of plasma FFA lead to ectopic lipid deposition and lipotoxicity. FFA accumulated in skeletal muscle are associated with insulin resistance and overall cellular dysfunction. Mechanisms supposed to be involved in these conditions include the Randle cycle, intracellular accumulation of lipid metabolites, inflammation and mitochondrial dysfunction or mitochondrial stress. These mechanisms are described and discussed in the view of current experimental evidence with an emphasis on conflicting theories of decreased vs. increased mitochondrial fat oxidation associated with lipid overload. Since different types of FFA may induce diverse metabolic responses in skeletal muscle cells, this review also focuses on cellular mechanisms underlying the different action of saturated and unsaturated FFA., J. Tumova, M. Andel, J. Trnka., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
8125. Excessive daytime sleepiness in the sleep apnoea syndrome (SAS) and in a combination of SAS and periodic limb movements in sleep measured by the multiple sleep latency test
- Creator:
- Volná, Jana, Kemlink, David, Pretl, Martin, Vaňková, Jitka, Švejdová, Kateřina, and Šonka, Karel
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- excessive daytime sleepiness (EDS), multiple sleep latency test (MSLT), night-time polysomnography (PSG), sleep apnoea syndrome (SAS), and periodic limb movements in sleep (PLMS)
- Language:
- English
- Description:
- Excessive daytime sleepiness (EDS) is, in its consequences, a major problem for the patient and for the society. EDS is mainly caused by night-time sleep disorders, in particular: the sleep apnoea syndrome (SAS) and periodic limb movements in sleep (PLMS). Our study was designed for finding out a) if there is a correlation between the gravity of the two conditions and the degree of EDS in patients with SAS and those with SAS and PLMS combined, and b) if EDS in the SAS+PLMS group is greater than in patients with the SAS alone. 35 patients with SAS and 10 with SAS+PLMS were examined using nocturnal polysomnography (PSG) and the multiple sleep latency test (MSLT). As for SAS, no correlation was found between EDS and the gravity of the condition. On the other hand, PLMS was found correlated to the mean sleep latency value. A correlation between the gravity of the disease and the reduced TST, SE and the sleep stages under study was corroborated for both groups. In addition, both conditions were found to interfere with the sleep architecture more than the SAS alone. This noctural sleep disturbance, though, would stop short of raising the mean sleep latency tested in the MLST. Correlations were found in SAS between the age and 2NREM latency and between the latter and average sleep latency. In the MSLT, the groups showed no difference as to the mean sleep latencies.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
8126. Excessive oxygen uptake during exercise and recovery in heavy exercise
- Creator:
- Yano, T., Yunoki, T., Matsuura, R., Arimitsu, T., and Kimura, T.
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, experimentální fyziologie, kyslík, experimental physiology, oxygen, excessive oxygen uptake, time constant, heavy exercise, moderate excercise, 14, and 612
- Language:
- English
- Description:
- The aim of this study was to determine whether excessive oxygen uptake (V.o2) occurs not only during exercise but also during recovery after heavy exercise. After previous exercise at zero watts for 4 min, the main exercise was performed for 10 min. Then recovery exercise at zero watts was performed for 10 min. The main exercises were moderate and heavy exercises at exercise intensities of 40 % and 70 % of peak V.o2, respectively. V.o2 kinetics above zero watts was obtained by subtracting V.o2 at zero watts of previous exercise (ΔV.o2). ΔV.o2 in moderate exercise was multiplied by the ratio of power output performed in moderate and heavy exercises so as to estimate the ΔV.o2 applicable to heavy exercise. The difference between ΔV.o2 in heavy exercise and ΔV.o2 estimated from the value of moderate exercise was obtained. The obtained V.o2 was defined as excessive V.o2. The time constant of excessive V.o2 during exercise (1.88±0.70 min) was significantly shorter than that during recovery (9.61±6.92 min). Thus, there was excessive V.o2 during recovery from heavy exercise, suggesting that O2/ATP ratio becomes high after a time delay in heavy exercise and the high ratio continues until recovery., T. Zano, T. Yunoki, R. Matsuura, T. Arimitsu, T. Kimura., and Obsahuje bibliografii a bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
8127. Exchange rings in which all regular elements are one-sided unit-regular
- Creator:
- Chen, Huanyin
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- exchange ring, one-sided unit-regularity, and idempotent
- Language:
- English
- Description:
- Let $R$ be an exchange ring in which all regular elements are one-sided unit-regular. Then every regular element in $R$ is the sum of an idempotent and a one-sided unit. Furthermore, we extend this result to exchange rings satisfying related comparability.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
8128. Exchange rings with stable range one
- Creator:
- Chen, Huanyin
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- exchange ring, stable range one, idempotent, and unit
- Language:
- English
- Description:
- We characterize exchange rings having stable range one. An exchange ring $R$ has stable range one if and only if for any regular $a\in R$, there exist an $e\in E(R)$ and a $u\in U(R)$ such that $a=e+u$ and $aR\cap eR=0$ if and only if for any regular $a\in R$, there exist $e\in r.ann(a^+)$ and $u\in U(R)$ such that $a=e+u$ if and only if for any $a,b\in R$, $R/aR\cong R/bR\Longrightarrow aR\cong bR$.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
8129. Excitability changes of cortical neurons during the postnatal period in rats exposed to prenatal hypobaric hypoxia
- Creator:
- Dana Marešová, Valkounová, I., Kateřina Jandová, Jana Bortelová, and Stanislav Trojan
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, hypoxie, hypoxia, development, excitability of neurons, rats, 14, and 612
- Language:
- English
- Description:
- Pregnant rats were exposed to intermittent hypobaric hypoxia (at a simulated altitude of 7000 m or 5000 m) and the excitability of cortical neurons of their pups was tested. Stimulation of the sensorimotor cortex of rats prenatally exposed to hypoxia shortened the duration of cortical afterdischarges in 12-day-old rats, but did not change the excitability in 25-day-old animals. Shortening of the first afterdischarge in 35-day-old rats but the prolongation of the first afterdischarge in adult rats (as compared to the duration of cortical afterdischarges in rats not exposed to prenatal hypoxia) were registered. The possible mechanisms of different excitability of cortical neurons in rats prenatally exposed to hypobaric hypoxia are discussed., D. Marešová, I. Valkounová, K. Jandová, J. Bortelová, S. Trojan., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
8130. Excitation energy transfer in cyanobacteria Synechocystis embedded in polymer film and partially bleached by polarized irradiation
- Creator:
- Goc, J., Klecha, K., Waszkowiak, A., Miyake, J., and Frąckowiak, D.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- absorption spectra, fluorescence spectra, photoacoustic spectra, phycobilisomes, and polarized radiation spectroscopy
- Language:
- Multiple languages
- Description:
- The polarized absorption, photoacoustic, fluorescence emission, and fluorescence excitation spectra of whole cells of cyanobacteria Synechocystis sp. embedded in a polymer film were measured. The bacteria cells, as it follows from anisotropy of absorption and fluorescence spectra, were even in a non-stretched polyvinyl alcohol film oriented to a certain extent. The measurements were done for such film in order to avoid the deformation of cyanobacteria shapes. Part of the samples was bleached by irradiation with strong polarized radiation with electric vector parallel to the orientation axis of cells. The anisotropy of photoacoustic spectra was higher than that of absorption spectra and it was stronger changed by the irradiation. Polarized fluorescence was excited in four wavelength regions characterised by different contribution to absorption from various bacteria pigments. The shapes of emission spectra were different depending on wavelength of excitation, polarization of radiation, and previous irradiation of the sample. The fluorescence spectra were analysed on Gaussian components belonging to various forms of pigments from photosystems (PS) 1 and 2. The results inform about excitation energy transfer between pools of pigments, differently oriented in the cells. Energy of photons absorbed by phycobilisomes was transferred predominantly to the chlorophyll of PS2, whereas photons absorbed by carotenoids to chlorophylls of PS1. and J. Goc ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public