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7272. Effect of drought stress on the photosynthesis of Acacia tortilis subsp. raddiana at the young seedling stage
- Creator:
- Kebbas, S., Lutts, S., and Aid, F.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, photosynthesis, gas exchange, growth parameters, stomata, sugar metabolism, water-use efficiency, Acacia tortilis, A. raddiana, 2, and 581
- Language:
- Multiple languages
- Description:
- Water stress usually impairs photosynthesis and plant growth. Acacia tortilis subsp. raddiana is well adapted to dry environments. The aim of the present study was to determine the impact of a progressive decrease in soil water content on photosynthetic-related parameters at the young seedling stage. Drought-induced plant responses occurred according to two types of kinetics. Water potential, stomatal conductance, and transpiration rates were rapidly affected by a decrease in soil water content, while chlorophyll fluorescence-related parameters and chlorophyll concentrations decreased only when soil water content was lower than 40%. The maximal efficiency of PSII photochemistry in the dark-adapted state remained unaffected by the treatment, whatever the stress duration. A. raddiana accumulated high concentrations of soluble sugars in relation to a stress-induced early stimulation of sucrose-phosphate synthase activity, while stimulation of invertase and sucrose synthase led to fructose accumulation only at the end of the stress period. We suggested that sugar accumulation may be involved in osmotic adjustment and protection of stressed tissues. A. raddiana was thus able to protect its photosynthetic machinery under drought conditions and may be considered as a promising species for revegetation of dry areas., S. Kebbas, S. Lutts, F. Aid., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
7273. Effect of drying on the sorption and desorption of copper in bottom sediments from water reservoirs and geochemical partitioning of heavy metals and arsenic
- Creator:
- Hiller, Edgar and Šutriepka, Michal
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- heavy metals, sorption, desorption, mobility, sequential extraction, dredged sediments, ťažké kovy, sorpcia, desorpcia, mobilita, sekvenčná extrakcia, and vyťažené sedimenty
- Language:
- Slovak
- Description:
- Bottom sediments can be significant sinks for a variety of heavy metals and metalloids coming from various anthropogenic sources. When these sediments are dredged and disposed of to land, drying and oxidation can lead to several changes in their physico-chemical properties, such as redox potential and pH, and hence to changes in metal mobility. Therefore, this work was conducted to study the adsorptiondesorption behaviour of one selected heavy metal - copper - in three bottom sediment samples before and after drying. Moreover, possible geochemical associations of As, Cd, Co, Cu, Hg, Ni, Pb and Zn in the airdried sediments were studied using a modified BCR sequential extraction protocol. Generally, redox state of the sediments changed from the highly anoxic to oxic and adsorption of Cu2+ decreased when the originally anoxic sediments were dried. On the other hand, the enhanced release of Cu2+ was observed from the air-dried sediments. The adsorption-desorption data showed that the changes in metal leachability occurred between originally anoxic and air dried sediments. In terms of water and soil pollution by Cu and likely other heavy metals, it appears that the dredged, air-dried sediments could represent somewhat greater contamination risks when compared with the originally anoxic sediments. Using the sequential extraction data, leaching potential of heavy metals and arsenic in the air-dried sediments was possible to evaluate with Cd, Co, Zn as the most mobile heavy metals, followed by Cu, Ni, As, Pb and Hg, respectively. and Dnové sedimenty sú významnými adsorbentmi celej rady ťažkých kovov a polokovov, ktoré pochádzajú z rôznych antropogénnych zdrojov. Po vyťažení týchto sedimentov z vodných nádrží na zemský povrch prechádzajú procesmi sušenia a oxidácie, ktoré menia niektoré ich vlastnosti, ako oxidačno-redukčný potenciál a pH, a teda môžu ovplyvňovať pohyblivosť potenciálne toxických kovov prítomných v sedimentoch. Z tohto dôvodu cieľom práce bolo štúdium adsorpcie a desorpcie jedného vybraného ťažkého kovu - medi - v troch vzorkách dnových sedimentov pred vysušením a po ňom. Okrem toho sme pomocou modifikovanej BCR metódy sekvenčnej extrakcie študovali možné geochemické interakcie ťažkých kovov (Cd, Co, Cu, Hg, Ni, Pb, Zn) a arzénu s jednotlivými zložkami dnových sedimentov. Ako ukázali experimentálne výsledky, počas sušenia sa zmenili redukčné podmienky v sedimentoch na oxidačné a adsorpčná kapacita vysušených sedimentov vzhľadom k Cu2+ bola výrazne nižšia ako u pôvodných sedimentov. Na druhej strane, množstvo uvoľneného Cu2+ z vysušených sedimentov bolo vyššie ako z pôvodných sedimentov. Uvedené zistenia teda poukazujú na zmenu v správaní a pohyblivosti potenciálne toxických prvkov medzi pôvodnými, redukčnými sedimentmi a tými, ktoré prešli procesom sušenia a oxidácie. Z hľadiska znečistenia prírodných vôd a pôd meďou a pravdepodobne aj ďalšími ťažkými kovmi sa zdá, že v porovnaní s pôvodnými kontaminovanými sedimentmi vyťažené a na vzduchu vysušené sedimenty môžu predstavovať vyššie riziko pre životné prostredie. Podľa výsledkov sekvenčnej extrakcie sa ukázalo, že Cd, Co a Zn sú po vysušení v skúmaných sedimentoch veľmi mobilnými prvkami, pričom pohyblivosť ostatných prvkov klesá v poradí Cu > Ni > As > Pb >> Hg.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
7274. Effect of ectomycorrhizal infection on growth and photosynthetic characteristics of Pinus densiflora seedlings grown under elevated CO2 concentrations
- Creator:
- Choi, D. S., Quoreshi, A. M., Maruyama, Y., Jin, H. O., and Koike, T.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- down-regulation, dry mass, phosphorus, Pinus densiflora, Pisolithus tinctorius, seedling diameter, stomatal limitation, and water use efficiency
- Language:
- Multiple languages
- Description:
- The effect of ectomycorrhizal Pisolithus tinctorius (Pt) infection was studied on the growth and photosynthetic characteristics of Pinus densiflora seedlings grown at ambient (360 µmol mol-1, AC) and elevated (720 µmol mol-1, EC) CO2 concentrations. After 18 weeks, Pt inoculation had led to significantly increased dry mass and stem diameter of P. densiflora at both CO2 concentrations, relative to non-inoculated seedlings. Moreover, EC significantly increased the ectomycorrhizal development. The phosphate content in needles inoculated with Pt was about three times higher than without inoculation at both CO2 concentrations. The PAR saturated net photosynthetic rates (Psat) of P. densiflora inoculated with Pt were clearly higher than for control seedlings at both CO2 concentrations, and the maximum net photosynthetic rate (PN) at saturated CO2 concentration (Pmax) was higher than in controls. Moreover, the carboxylation efficiency (CE) and RuBP regeneration rate of the PN/Ci curve for P. densiflora inoculated with Pt were significantly higher than for non-inoculated seedlings at both CO2 concentrations, especially at EC. The water use efficiency (WUE) of seedlings inoculated with Pt grown at EC was significantly raised. Allocation of photosynthates to roots was greater in Pt inoculated pine seedlings, because of the enhanced activity of ectomycorrhiza associated with seedlings at EC. Moreover, PN of non-inoculated seedlings grown for 18 weeks at EC tended to be down regulated; in contrast, Pt inoculated seedlings showed no down-regulation at EC. The activity of ectomycorrhiza may therefore be enhanced physiological function related to water and phosphate absorption in P. densiflora seedlings at EC. and D. S. Choi ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
7275. Effect of elevated carbon dioxide concentration on the stomatal parameters of rice cultivars
- Creator:
- Uprety, D. C., Dwivedi, N., Jain, V., and Mohan, R.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- epidermal cell size and density, leaf area and dry mass, net photosynthetic rate, open top chamber, Oryza sativa, stomatal size and density, stomatal conductance, and stroma
- Language:
- Multiple languages
- Description:
- The response of stomatal parameters of four rice cultivars to atmospheric elevated CO2 concentration (EC) was studied using open top chambers. EC brought about reduction in stomatal conductance and increase in stomatal index, size of stomatal guard cells, stroma, and epidermal cells. Such acclimation helped the regulation of photosynthesis to EC. These changes in stomatal characters made rice cultivars adjustable to EC environment. and D. C. Uprety ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
7276. Effect of elevated CO2 on photosynthesis and chlorophyll fluorescence of rose plants grown at high temperature and high photosynthetic photon flux density
- Creator:
- Urban, L., Barthélémy, L., Bearez, P., and Pyrrha, P.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carotenoids, chlorophyll, cultivar differences, leaf coonductance to water vapour, Rosa hybrida, saccharides, and stomata
- Language:
- Multiple languages
- Description:
- Gas exchange and chlorophyll (Chl) fluorescence were measured on young mature leaves of rose plants (Rosa hybrida cvs. First Red and Twingo) grown in two near-to-tight greenhouses, one under control ambient CO2 concentration, AC (355 µmol mol-1) and one under CO2 enrichment, EC (700 µmol mol-1), during four flushes from late June to early November. Supply of water and mineral elements was non-limiting while temperature was allowed to rise freely during daytime. Leaf diffusive conductance was not significantly reduced at EC but net photosynthetic rate increased by more than 100 %. Although the concentration of total non-structural saccharides was substantially higher in the leaves from the greenhouse with EC, ΦPS2 (quantum efficiency of radiation use) around noon was not significantly reduced at EC indicating that there was no down-regulation of electron transport. Moreover, CO2 enrichment did not cause any increase in the risk of photo-damage, as estimated by the 1 - qP parameter. Non-photochemical quenching was even higher in the greenhouse with EC during the two summer flushes, when temperature and photosynthetic photon flux density (PPFD) were the highest. Hence rose photosynthesis benefits strongly from high concentrations of atmospheric CO2 at both high and moderate temperatures and PPFD. and L. Urban ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
7277. Effect of ethanol on tracheal potassium channels reconstituted into bilayer lipid membranes
- Creator:
- Komínková, V., Magová, M., Mojžišová, A., Máleková, Ľ., and Ondriaš, K.
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, fyziologie, physiology, potassium channel, trachea - ethanol, bilayer lipid membrane, bronchodilation, 14, and 612
- Language:
- English
- Description:
- We examined the effect of ethanol on single potassium channels derived from plasma membranes of bovine tracheal smooth muscles. The observed potassium channels had a conductance of 296±31 pS (mean ± S.D.) in symmetrical 250 mmol/l KCl solutions, and exhibited a voltage- and Ca2+-dependence similar to BKCa channels. Ethanol at 50, 100 and 200 mM concentrations increased the probability of open potassium channels to 112±5, 127±7 and 121±13% (mean ± S.E.M.), respectively. It is suggested that increased activity of the BKCa channels by ethanol hyperpolarizes the plasma membrane and thus may contribute to relaxation of tracheal smooth muscle., V. Komínková, M. Magová, A. Mojžišová, Ľ. Máleková, K. Ondriaš., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
7278. Effect of exercise on markers of vascular health in renal transplant recipients
- Creator:
- Jiří Piťha, Králová Lesná, I., Petr Stávek, Andrea Mahrová, Bacek, J., Sekerková, A., Vladimír Teplan, and Milena Štollová
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, tělesná cvičení, exercises, renal transplantation, endothelial progenitor cells, circulating microparticles, asymmetric climethyl arginine, 14, and 612
- Language:
- English
- Description:
- The cornerstone of cardiovascular risk management is lifestyle intervention including exercise which could exert favorable impact also in renal transplant recipients. Nevertheless, reliable assessment of the effect of lifestyle interventions is complicated and the available data in this population are not consistent. The aim of the study was to evaluate the effect of physical activity on selected laboratory markers of vascular health including circulating stem cells, endothelial progenitor cells, microparticles, and plasma asymmetric dimethyl arginine in renal transplant recipients. Nineteen men and 7 women were recruited in 6-month program of standardized and supervised exercise. Control group consisted of 23 men and 13 women of similar age and body mass i ndex not included into the program. One year after the transplantation, the main difference between intervention and control group was found in the change of endothelial progenitor cells (p=0.006). Surprisingly, more favorable change was seen in the contro l group in which endothelial progenitor cells significantly increased compared to the intervention group. The explanation of this finding might be a chronic activation of reparative mechanisms of vascular system in the population exposed to multiple risk factors which is expressed as relatively increased number of endothelial progenitor cells. Therefore, their decrease induced by exercise might reflect stabilization of these processes., J. Piťha, I. Králová Lesná, P. Stávek, A. Mahrová, J. Racek, A. Sekerková, V. Teplan, M. Štollová., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
7279. Effect of fast protein liquid chromatography fractionated salivary gland extracts from different ixodid tick species on interleukin-8 binding to its cell receptors
- Creator:
- Kocáková, Paulína, Sláviková, Monika, Hajnická, Valéria, Slovák, Mirko, Gašperík, Juraj, Vančová, Iveta, Fuchsberger, Norbert, and Nuttall, Patricia A.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Dermacentor reticulatus, Rhipicephalus appendiculatus, Amblyomma variegatum, interleukin-8, tick saliva, chemokine inhibitors tick species - Dermacentor reticulatus (Fabricius, 1794), Rhipicephalus appendiculatus Neumann, 1901, and and Amblyomma
- Language:
- English
- Description:
- Interleukin-8 plays a critical role in inflammatory processes. Hence generation of molecules with anti-IL-8 activity is likely to be important for successful feeding and for survival of the ticks. Anti-IL-8 activity was studied in saliva of three ixodid tick species - Dermacentor reticulatus (Fabricius, 1794), Rhipicephalus appendiculatus Neumann, 1901, and Amblyomma variegatum (Fabricius, 1794). The greatest activity was shown in saliva prepared from D. reticulatus. The activity was attributed to tick salivary gland molecules that bind to IL-8, preventing binding of the chemokine to its specific receptor, rather than to occupation of the IL-8 cell receptor by the tick molecules. The distribution of anti-IL-8 activity in fast protein liquid chromatography (FPLC) fractions of salivary gland extracts (SGE) derived from adult female D. reticulatus, R. appendiculatus and A. variegatum was compared directly by both ELISA and receptor-binding inhibition assays. The correspondence in results with fractions of SGE from ELISA is consistent with detection of tick molecules that inhibit IL-8 binding to its receptor. As IL-8 is an important chemoattractant and activator of neutrophils, the presence of an anti-IL-8 activity in tick saliva indicates that neutrophils play an important role in the host response to parasitism by ticks.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
7280. Effect of fasting and refeeding on duodenal alkaline phosphatase activity in monosodium glutamate obese rats
- Creator:
- Raček, Ľ., Ľudovít Lenhardt, and Mozeš, Š.
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, obezita, obesity, fasting / refeeding, duodenal alkaline phosphatase, monosodium glutamate, obese rats, 14, and 612
- Language:
- English
- Description:
- a1_In the present work the effects of fasting and refeeding on fat pad weight and alkaline phosphatase activity in the brush border of individual duodenal enterocytes have been evaluated in male Wistar rats with obesity induced by monosodium glutamate (MSG) treatment during the early postnatal period. Neonatal rats were treated subcutaneously with MSG (2 mg/g b.w.) or saline (controls) for 4 days after birth. At 4 months of age, two types of experiments were performed. In the first experiment rats, were submitted to 3 or 6 days lasting food deprivation. In the second experiment the rats were refed for 3 or 6 days ad libitum or restrictedly (60 % of pre-fasting intake) after a 6 day-fasting period. Fasting and refeeding influenced the body fat and function of the duodenum in MSG-treated rats differently as compared to the controls. However, alkaline phosphatase activity and the weight of epididymal and retroperitoneal fat depots were significantly increased in MSG obese rats (P<0.001) during all the periods examined. While 3 days of food deprivation resulted in both groups in a similar loss of adipose tissue weight and alkaline phosphatase activity, the decrements of these parameters after 6 days of fasting were lower in obese rats suggesting that their capacity to spare body fat stores was enhanced. After 3 days of ad libitum refeeding, a more marked adaptational increase of food consumption and also a significantly increased alkaline phosphatase activity above the pre-fasting level (P<0.01) was observed in the MSG-treated rats. Consequently, a more rapid body fat restoration was demonstrated in these animals. Refeeding of rats at 60 % of the pre-fasting intake level resulted in a significant increase of alkaline phosphatase activity in both the MSG and control group; moreover, as food restriction continued, MSG-treated rats tended to further increase the enzyme activity., a2_Our results revealed that MSG treatment of neonatal rats may significantly change the intestinal functions. Permanently increased alkaline phosphatase activity observed in MSG obese rats during all investigated periods suggests that this functional alteration is probably not a consequence of actual nutritional variation but could be a component of regulatory mechanisms maintaining their obesity at critical values., Ľ. Raček, Ľ. Lenhardt, Š. Mozeš., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public