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7522. Effects of rapidly imposed water deficit on photosynthetic parameters of three C4 grasses
- Creator:
- Soares-Cordeiro, A. S., Carmo-Silva, A. E., Bernardes da Silva, A., Marques da Silva, J., Keys, A. J., and Arrabaça, M. C.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll a fluorescence, drought stress, NAD-malic enzyme, NADP-malic enzyme, phosphoenolpyruvate carboxykinase, phosphoenolpyruvate carboxylase, photosynthetic capacity, and Rubisco
- Language:
- Multiple languages
- Description:
- Water deficit, when rapidly imposed on three C4 grasses of the different metabolic subtypes, Paspalum dilatatum Poiret (NADP-malic enzyme), Cynodon dactylon (L.) Pers (NAD-malic enzyme) and Zoysia japonica Steudel (phosphoenolpyruvate carboxykinase), caused decreases in photosynthetic rates, in the quantum yield of PS II and photochemical quenching, and in the activities of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and phosphoenolpyruvate carboxylase (PEPC). The results provide evidence for non-stomatal limitations of photosynthesis differing in nature between the three species. and A. S. Soares-Cordeiro ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
7523. Effects of rate of decrease in power output in decrement-load exercise on oxygen uptake
- Creator:
- Yano, T., Yunoki, T., Matsuura, T., Arimitsu, T., and Kimura, T.
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- experimentální fyziologie, kyslík, experimental physiology, oxygen, spotřeba kyslíku, kyslíkový dluh, oxygen uptake, oxygen debt, decrement-load exercise, and rate of decrease in power output
- Language:
- English
- Description:
- The purpose of this study was to examine how oxygen uptake (V.o2) in decrement-load exercise (DLE) is affected by changing rate of decrease in power output. DLE was performed at three different rates of decrease in power output (10, 20 and 30 watts ・min-1: DLE10, DLE20 and DLE30, respectively) from power output corresponding to 90 % of peak V.o2. V.o2 exponentially increased and then decreased, and the rate of its decrease was reduced at low power output. The values of V.o2 in the three DLE tests were not different for the first 2 min despite the difference in power output. The relationship between V.o2 and power output below 50 watts was obtained as a slope to estimate excessive V.o2 (ex-V.o2) above 50 watts. The slopes were 10.0±0.9 for DLE10, 9.9±0.7 for DLE20 and 10.2±1.0 ml ・min-1 ・ watt-1 for DLE30. The difference between V.o2 estimated from the slope and measured V.o2 was defined as ex-V.o2. The peak value of ex-V.o2 for DLE10 (189±116 ml ・min-1) was significantly greater than those for DLE20 and for DLE30 (93±97 and 88±34 ml ・min-1). The difference between V.o2 in DLE and that in incremental-load exercise (ILE) below 50 watts (ΔV.o2) was greater in DLE 30 and smallest in DLE10. There were significant differences in ΔV.o2 among the three DLE tests. The values of ΔV.o2 at 30 watts were 283±152 for DLE10, 413±136 for DLE20 and 483±187 ml ・min-1 for DLE30. Thus, a faster rate of decrease in power output resulted in no change of V.o2 at the onset of DLE, smaller ex-V.o2 and greater ΔV.o2. These results suggest that V.o2 is disposed in parallel in each motor unit released from power output or recruited in DLE., T. Yano, 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
7524. Effects of realistically simulated, elevated UV irradiation on photosynthesis and pigment composition of the alpine snow alga Chlamydomonas nivalis and the arctic soil alga Tetracystis sp. (Chlorophyceae)
- Creator:
- Remias, D., Albert, A., and Lütz, C.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, microalgae, secondary cartenoids, sun simulator, and UV-B exposure
- Language:
- Multiple languages
- Description:
- An indoor sun simulator was used to provide elevated UV-B radiation (280-315 nm) in combination with realistic ratios to PAR (400-700 nm) and UV-A radiation (315-400 nm) in order to test the physiological response of a soil- and snow microalga during a three-day stress scenario, which may occasionally occur in their respective arctic and alpine habitats. Chlamydomonas nivalis and Tetracystis sp. are initial colonizers of harsh habitats like summer snow fields and bare arctic soils. The two species were chosen because of their role as primary successors in places where life is generally limited by extreme climatic and nutritional conditions. The influence of the increased UV-B irradiation (1.43 W m-2; control: 0.52 W m-2) on photosynthesis and pigment composition was measured. Both species survived this incubation without any morphological signs of damage, but oxygen production was reduced by 20-56%. Under control conditions, the amount of chlorophylls (Chls) and carotenoids (Cars) per dry mass increased after three days due to optimal light conditions. After the same period, the treated samples of the soil alga Tetracystis sp. showed a smaller increase in Chls and primary Cars than the control. However, the production of extraplastidal, secondary Cars was induced. On the contrary, the snow alga C. nivalis already had high amounts of secondary Cars before the experiment, and after exposure, all pigment classes increased more compared to control conditions. The results show that these microalgae can tolerate short episodes of enhanced UV-B radiation. Photosynthesis may be temporally impaired, but the cells respond by the production of secondary Cars, which can shield their chloroplasts against excessive irradiation or quench reactive oxygen species. and D. Remias, A. Albert, C. Lütz.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
7525. Effects of reddening of cotton (Gossypium hirsutum L.) leaves on functional activity of photosynthetic apparatus
- Creator:
- Velikova, V., Tsonev, T., Edreva, A., Gürel, A., and Hakerlerler, H.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll fluorescence, net photosynthetic rate, stomatal conductance, transpiration rate, and water use efficiency
- Language:
- Multiple languages
- Description:
- Strong inhibition of rates of CO2 assimilation and transpiration, stomatal conductance, and water use efficiency as well as photosystem 2 (PS2) photochemical activity were related to the severity of reddening. The inhibition of photosynthesis in red cotton leaves was due to both decreased photochemical activity and stomatal limitation. Lowered photosynthetic capacity could be one of the main factors of reduced yield in reddening cotton. and V. Velikova ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
7526. Effects of reduced irradiance on leaf morphology, photosynthetic capacity, and fruit yield in olive (Olea europaea L.)
- Creator:
- Gregoriou, K., Pontikis, K., and Vemmos, S.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- areal leaf mass, chlorophyll, chloroplasts, fruit yield, leaf anatomy, net photosynthetic rate, shade, stomata, and trichomes
- Language:
- Multiple languages
- Description:
- One-year-old olive trees (cv. Koroneiki) were grown in plastic containers of 50 000 cm3 under full daylight and 30, 60, and 90 % shade for two years. The effects of shade on leaf morphology and anatomy, including stomatal density and chloroplast structure, net photosynthetic rate (PN), stomatal conductance (gs), and fruit yield were studied. Shade reduced leaf thickness due to the presence of only 1-2 palisade layers and reduced the length of palisade cells and spongy parenchyma. The number of thylakoids in grana as well as in stroma increased as shade increased, while the number of plastoglobuli decreased in proportion to the reduced photosynthetically active radiation (PAR). The higher the level of shade, the lower the stomatal and trichome density, leaf mass per area (ALM), gs, and PN. Shade of 30, 60, and 90 % reduced stomatal density by 7, 16, and 27 %, respectively, while the corresponding reduction in PN was 21, 35, and 67 %. In contrast, chlorophyll a+b per fresh mass, and leaf width, length, and particularly area increased under the same shade levels (by 16, 33, and 81 % in leaf area). PN reduction was due both to a decrease in PAR and to the morphological changes in leaves. The effect of shade was more severe on fruit yield per tree (32, 67, and 84 %) than on PN indicating an effect on bud differentiation and fruit set. The olive tree adapts well to shade compared with other fruit trees by a small reduction in stomatal and trichome density, palisade parenchyma, and a significant increase in leaf area. and K. Gregoriou, K. Pontikis, S. Vemmos.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
7527. Effects of relative submergence and bed slope on sediment incipient motion under decelerating flows
- Creator:
- Bolhassani, Ramin, Afzalimehr, Hossein, and Dey, Subhasish
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- fluvial hydraulics, open channel flow, river beds, sediment transport, shear stress, and streamflow
- Language:
- Slovak
- Description:
- This paper presents the results of an experimental study to quantify the effects of bed slope and relative submergence on incipient motion of sediment under decelerating flows. Experiments were conducted in an experimental tilting-flume of 8 m long 0.4 m wide and 0.6 m deep with glass-walls. Three uniform sediments with median grain sizes of 0.95, 1.8 and 3.8 mm and three bed slopes of 0.0075, 0.0125 and 0.015 were used under decelerating flow. The main conclusion is that the Shields diagram, which is commonly used to evaluate the critical shear stress, is not suitable to predict the critical shear stress under decelerating flows.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
7528. Effects of resistance training on arterial compliance and plasma endothelin-1 levels in healthy men
- Creator:
- Tagawa, K., Ra, S.-G., Maeda, S., Miyauchi, T., Sakai, S., Takekoshi, K., Yoshida, Y., Yoshikawa, T., and Kumagai, H
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fyziologie člověka, human physiology, Resistance training, Carotid arterial compliance, Vasoconstrictor, Young men, Endothelin, EDCF, 14, and 612
- Language:
- English
- Description:
- Arterial compliance (AC) is an index of the elasticity of large arteries. Endothelial dysfunction has been reported to result in reduced arterial compliance, which represents increased arterial stiffness. A reduction in AC is elicited by high-intensity resistance training, however the mechanisms are obscure. Because a single bout of resistance exercise causes a transient increase in circulating plasma endothelin-1 in humans, some vasoconstrictors may play a role in the mechanisms. The present study aimed to investigate whether resistance training-induced decrease in AC is associated with changes in circulating vasoconstrictors levels in young men. Young sedentary men were assigned to control (n=5) or training (n=9) groups. The training group performed four-week high-intensity resistance training (weight training exercise; three sessions/week). We measured AC and plasma levels of endothelin-1, angiotensin II, and norepinephrine before and after intervention. Resistance training significantly decreased AC, whereas the changes in plasma levels of neither endothelin-1, nor angiotensin II, nor norepinephrine were significantly different between the control and the training groups. Moreover, we found no significant correlations between changes in circulating plasma levels (endothelin-1, angiotensin II, and norepinephrine) and in the AC. Despite of no alteration of the resting circulating plasma levels (endothelin-1, etc.), we cannot exclude a possibility that the tissue/local concentrations of vasoconstrictors (endothelin-1, etc.) around the vessels might be increased and also involved in a reduction of AC in the training group. Taken together, the present results suggest that circulating vasoconstrictors (endothelin-1, etc.) in plasma are not involved in a reduction in AC by the resistance training., K. Tagawa, S.-G. Ra, H. Kumagai, T. Yoshikawa, Y. Yoshida, K. Takekoshi, S. Sakai, T. Miyauchi, S. Maeda., and Seznam literatury
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
7529. Effects of rhizobia inoculation and nitrogen fertilization on photosynthetic physiology of soybean
- Creator:
- Zhou, X.-J., Liang, Y., Chen, H., Shen, S.-H., and Jing, Y.-X.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- biological nitrogen fixation, biomass, carboxylation efficiency, carotenoids, chlorophyll fluorescence, Glycine max, intercellular CO2 concentration, leaf area, stomatal conductance, and quantum yield
- Language:
- Multiple languages
- Description:
- Plant growth, contents of photosynthetic pigments, photosynthetic gas exchange, and chlorophyll (Chl) fluorescence in soybean [Glycine max (L.) Merr. cv. Heinong37] were investigated after it was inoculated with Sinorhizobium fredii USDA191 or treated with 5 mM (NH4)2SO4 (N5) and 30 mM (NH4)2SO4 (N30), respectively. In the plants following N5 fertilization, not only plant biomass, leaf area, and Chl content, but also net photosynthetic rate (PN), stomatal conductance (gs), carboxylation efficiency (CE), maximum photochemical efficiency (Fv/Fm) of photosystem 2 (PS2), and quantum yield of PS2 (ΦPS2) were markedly improved as compared with the control plants. There were also positive effects on plant growth and plant photosynthesis after rhizobia inoculation, but the effects were much less than those of N5 fertilization. For N30 plants there were no significant positive effects on plant growth and photosynthetic capacity. Plant biomass, PN, and gs were similar to those of N-limited (control) plants. ΦPS2 and photochemical quenching (qP) were obviously declined while content of carotenoids and non-photochemical quenching (qN) were significantly enhanced in N30 treated plants. This indicated that excess N supply may cause some negative effects on soybean plants. and X.-J. Zhou ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
7530. Effects of roflumilast, a phosphodiesterase-4 inhibitor, on the lung functions in a saline lavage-induced model of acute lung injury
- Creator:
- Kosutova, P., Mikolka, P., Kolomaznik, M., Rezakova, S., Andrea Čalkovská, and Daniela Mokrá
- Format:
- print, bez média, and svazek
- Type:
- article, články, journal articles, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, plíce, záněty, lungs, inflammations, roflumilast, lung injury, lung functions, 14, and 612
- Language:
- English
- Description:
- Acute lung injury (ALI) is associated with det erioration of alveolar-capillary lining and transmigration and activation of inflammatory cells. Whereas a selective phosphodiesterase-4 (PDE4) inhibitor roflumilast has exerted potent anti-inflammatory properties, this study evaluated if its intravenous delivery can influence inflammation, edema formation, and respiratory parameters in rabbits with a lavage-induced model of ALI. ALI was induced by repetitive saline lung lavage (30 ml/kg). Animals were divided into 3 groups: ALI without therapy (ALI), ALI treated with roflumilast i.v. (1 mg/kg; ALI+Rofl), and healthy ventilated controls (Control), and were ventilated for following 4 h. Respiratory parameters (blood gases, ventilatory pressures, lung compliance, oxygenation indexes etc.) were measured and ca lculated regularly. At the end of experiment, animals were overdosed by anesthetics. Total and differential counts of cells in bronchoalveolar lavage fluid (BAL) were estimated microscopically. Lung edema was expressed as wet/dry lung weight ratio. Treatment with roflumilast reduced leak of cells (P<0.01), particularly of neutrophils (P<0.001), into the lung, decreased lung edema formation (P<0.01), and improved respiratory parameters. Concluding, the results indicate a future potential of PDE4 inhibitors also in the therapy of ALI., P. Kosutova, P. Mikolka, M. Kolomaznik, S. Rezakova, A. Calkovska, D. Mokra., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public