In our study, one-month-old Melissa officinalis plants were subjected to Fe-deficiency treatments, such as 10 µM Fe (as direct iron deficiency, DD), and 30 µM Fe + 10 mM NaHCO3 + 0.5 g l-1 CaCO3 (as indirect iron deficiency, ID), and 30 µM Fe (as control) for 14 d. Both Fe-deficiency types reduced plant growth, photosynthetic pigment contents, an active Fe content in roots and leaves, root Fe(III)-reducing capacity, Fe-use efficiency, maximal quantum yield of PSII photochemistry, a ratio of variable to basic fluorescence, and activities of antioxidant enzymes, while they increased lipid peroxidation and a H2O2 content in leaves. These effects were more pronounced in plants exposed to ID with bicarbonate than those of DD plants. We showed that sodium nitroprusside (SNP), as NO donor, could ameliorate the adverse effects of bicarbonate on above traits. The methylene blue, as NO blocker, reversed the protective effects conferred by SNP in the ID-treated plants as well as DD plants. These findings suggests that NO protects photosynthesis and growth of IDtreated plants as well as DD plants by contribution in availability and/or delivery of metabolically active iron or by changing activities of reactive oxygen species-scavenging enzymes., R. Amooaghaie, Sh. Roohollahi., and Obsahuje bibliografii
Fluorescence spectroscopy at 77 K showed that the application of glucose lead to the depletion of phycobilisomes (PBS) and photosystems (PS) 2 and 1, and that PS2 was more sensitive to glucose than PS1. The application of sodium thiosulfate, an effective scavenger of reactive oxygen intermediates, counteracted the effects of glucose. Sodium thiosulfate effectively protected photosynthetic apparatus, PS2, PS1, and PBS against glucose-induced depletion. Sodium thiosulfate showed strong capability to inhibit the disappearance of chlorophyll induced by glucose. At a relatively low concentration of glucose, the application of sodium thiosulfate can even be helpful for the assembly of photosynthetic apparatus. Hence the reactive oxygen species might be involved in the depletion of the photosynthetic apparatus in the cyanobacterium Synechocystis sp. PCC 6803 cells grown in the presence of glucose. and Zeneng Wang ... [et al.].
Content-based composites are traditionally a commonly used material in civil engineering structures. The basic representative of this type of material is concrete, a quasi-brittle composite in which crack resistance can be achieved by the addition of fibres. The double-K fracture model can be used to calculate the fracture-mechanical parameter values of structural concrete with and without popypropylene fibres. This model combines the concept of cohesive forces acting on the crack length with a criterion based on the stress intensity factor, using a ‘softening function‘ to determine the cohesive part of fracture toughness. In this paper, authors determine the effect of the type of this softening function on the evaluation of fracture tests performed on sets of concrete specimens with and without polypropylene fibres. and Obsahuje seznam literatury
a1_The photosynthetic and chlorophyll fluorescence parameters were studied in Ziziphus jujuba var. spinosus under different soil water gradients obtained by irrigation and natural water consumption. We used the rectangular hyperbola model, the nonrectangular hyperbola model, the exponential model, and the modified rectangular hyperbola model to fit our data and evaluate them quantitatively. Based on the relationship among the parameters, the effects of the availability of soil water on photosynthesis were elucidated. The results showed that: (1) The relationship between water content and photosynthetic parameters were fitted best by the modified rectangular hyperbola model, followed by the nonrectangular hyperbola model, the exponential model, and the rectangular hyperbola model. The modified rectangular hyperbola model fitted best the maximum net photosynthetic rate (PNmax) and the light-saturation point (LSP), while the nonrectangular hyperbola model fitted best the dark respiration rate (RD), the apparent quantum yield (AQY), and the light-compensation point (LCP)., a2_(2) The main reason for the net photosynthetic rate (PN) decline was that it reached a stomatal limit when the soil relative water content (RWC) was greater than 25% and it reached a nonstomatal limit when the RWC was lesser than 25%. Under these conditions, the photosynthetic apparatus of Z. jujuba was irreversibly damaged. (3) Pmax, RD, AQY, and LSP increased first and then decreased, while LCP increased contrary to the RWC. The P N light-response parameters reached optimum when the RWC was 56-73%. (4) The quantum yield of PSII photochemistry reached a maximum when RWC was 80%. Nonphotochemical quenching decreased rapidly, and the minimum fluorescence in the dark-adapted state increased rapidly when RWC was lesser than 25%. Under these conditions, PSII was irreversibly damaged. (5) The RWC range of 11-25% resulted in low productivity and low water use efficiency (WUE). The RWC range of 25-56% resulted in moderate productivity and moderate WUE, and the RWC range of 56-80% resulted in high productivity and high WUE. The RWC range of 80-95% resulted in moderate productivity and low WUE. In summary, photosynthesis of Z. jujuba was physiologically adaptable in response to water stress in sand formed from seashells. The photosynthetic and physiological activity was maintained relatively high when the RWC was between 56 and 80%; Z. jujuba seedlings grew well under these conditions., J. B. Xia, G. C. Zhang, R. R. Wang, S. Y. Zhang., and Obsahuje bibliografii
Ionizing radiation and somatostatin analogues are used for acromegaly treatment to achieve normalization or reduction of growth hormone hypersecretion and tumor shrinkage. In this study, we investigated a combination of somatostatin (SS14) with ionizing radiation of 60Co and its effect on reparation of radiation-induced damage and cell death of somatomammotroph pituitary cells GH3. Doses of γ-radiation 20-50 Gy were shown to inhibit proliferation and induce apoptosis in GH3 cells regardless of somatostatin presence. It has been found that the D0 value for GH3 cells was 2.5 Gy. Somatostatin treatment increased radiosensitivity of GH3 cells, so that D0 value decreased to 2.2 Gy. We detected quick phosphorylation of histone H2A.X upon irradiation by the dose 20 Gy and its colocalization with phosphorylated protein Nbs-1 in the site of double strand break of DNA (DSB). Number of DSB decreased significantly 24 h after irradiation, however, clearly distinguished foci persisted, indicating non repaired DSB, after irradiation alone or after combined treatment by irradiation and SS14. We found that SS14 alone triggers phosphorylation of Nbs1 (p-Nbs1), which correlates with antiproliferative effect of SS14. Irradiation also increased the presence of p-Nbs1. Most intensive phosphorylation of Nbs1 was detected after combined treatment of irradiation and SS14. The decrease of the number of the DSB foci 24 h after treatment shows a significant capacity of repair systems of GH3 cells. In spite of this, large number of unrepaired DSB persists for 24 h after the treatment. We conclude that SS14 does not have a radioprotective effect on somatomammotroph GH3 cells., M. Řezáčová, J. Čáp, D. Vokurková, E. Lukášová, J. Vávrová, J. Cerman, V. Mašín, N. Mazánková., and Obsahuje bibliografii a bibliografické odkazy
Somatotropin treatment does not stimulate body growth in guinea-pigs, whereas it is effective in stimulation of both cytosolic and nuclear uterine ooestradiol receptor concentration in the animals fed optimum amounts of ascorbic acid. To determine whether this effect of somatotropin is ascorbic acid-dependent, guinea-pigs of 9 weeks of age with marginal vitamin C deficiency were treated with either recombinant bovine somatotropin (bST; 0.5 mg per animal) or vehicle for 10 days. The amount of available cytosolic ooestradiol receptor per unit of uterine weight, the DNA content, or in whole uteri was increased in somatotropin-treated animals (3.3 to 5.9- fold) compared to controls. However, the nuclear uterine oestradiol receptor concentration was not increased. The dissociation constant values were significantly higher in the cytosol (control: 2.79, bST-treated: 2.66) than in the nuclear fraction (control: 1.76, bST-treated: 1.80) and did not differ between control and bST treated animals. The results of this investigation demonstrate that guinea-pigs with marginal vitamin C deficiency provide a suitable model for studying the effect of vitamin C on somatotropin action. The possible synergistic action of ascorbic acid on uterine action of somatotropin is discussed.
Sophoridine is a type of alkaloid extract derived from the Chinese herb Sophora flavescens Ait (kushen) and possess a variety of pharmacological effects including anti- inflammation, anti - anaphylaxis, anti - cancer, anti - arrhythmic and so on. However, the effect of sophoridine on heart failure has not been known yet. In this study, the effect of sophoridine on heart failure was investigated using Sprague -Dawley (SD) rat model of chronic heart failure. Morphological results showed that in medium and high dose group, myofilaments were arranged orderly and closely, intermyofibrillar ly sis disappeared and mitochondria contained tightly packed cristae compared with heart failure group. We investigated the Ca 2+ induced Ca 2+ transients and assessed the expression of ryanodine receptor (RyR2) and L-type Ca 2+ channel (dihydropyridine receptor, DHPR). We found that the cytosolic Ca 2+ transients were markedly increas ed in amplitude in medium ( ΔF/F 0 =43.33±1.92 ) and high dose groups ( ΔF/F 0 =47.21 ±1.25 ) compared with heart failure group ( ΔF/F 0 =16.7±1.29, P <0.0 1), Moreover, we demonstrated that the expression of cardiac DHPR was significantly increased in medium - and high dose -group compared with heart failure rats. Our results suggest that sophoridine could improve heart failure by ameliorating cardiac Ca 2+ induced Ca 2+ transients, and that thi s amelioration is associated with upregulation of DHPR., S.-T. Hu, Y.-F. Shen, J.-M. Gong, Y.-J. Yang., and Obsahuje bibliografii
Both the synthesis of apoprotein P700 with molecular mass of 72 kDa and asseinbly of chlorophyll (Chl) a-protein of photosystem (PS) 1 were blocked by lincoinycin (inhibitor of translation in chloroplasts). Synthesis of 48 and 43,5 kDa polypeptides belonging to the PS2 complex were also suppressed. Chl a forms of PS2 reaction centi e (RC) at 683 nin and of PS 1 RC at 690, 696 and 705 nm disappeared, Relative Chl h content and fluorescence bands ratio F736/F686 increased significantly Cycloheximide (inhibitor of translation in cytoplasin) ti eatinent resulted in reduction of polypeptides of the light-harvesting Chl a//i-protein complex (LFIC) in the 28.5- 25.5 kDa region. At the same time a relatively smaller decrease was observed of two Chl foirns of the LHC: Chl by 3.8 % and Chl by 10.2 % (12.4 and 34.3 % in the contiol, respectively). The fluorescence bands ratio F736/F686 decrease in low temperature spectra was possibly connected with the LIlC-1 and LIlC-2 synthesis blocking.