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排序方式： 共有207条查询结果，搜索用时 218 毫秒
81.
Maria Skłodowska Ewa Gajewska Elżbieta Kuźniak Artur Mikiciński Piotr Sobiczewski 《Scientia Horticulturae》2010
BTH (S-methylbenzo-1,2,3-thiadiazole-7-carbothiate), an active compound of the commercial preparation Bion, has been studied as an elicitor of resistance to fire blight (Erwinia amylovora) in apple. However, the biochemical mechanisms of its action are not fully elucidated. Our study indicated that BTH at the best time of its protection activity (2–14 days after application) induced changes in prooxidant–antioxidant balance in the leaves of apple trees, but in different ways in the enzymatic and nonenzymatic antioxidants. Glutathione as low molecular antioxidant as well as superoxide anion radical and lipid peroxides as oxidants exhibited changes at the early phase of BTH action. Glutathione-dependent enzymes were strongly affected by the elicitor used. On the 2nd day glutathione transferase (GST) and glutathione peroxidase (GSH-Px) activities increased by about 70% and 30% above the control, respectively. GST activity normalized about the 14th day but GSH-Px at the same time showed 27% of the control value. Among enzymes utilising hydrogen peroxide only catalase showed increase (37%) at the early phase of experiment. Compared with the control, BTH-treated plants did not show changes in ascorbate peroxidase and phenylalanine ammonia-lyase activities. Tocopherol (TOC) level diminished starting from the 7th day after BTH treatment and on the 14th day it was only 28% of the control. It is proposed that extinguishing of BTH-mediated signal resulted from TOC and glutathione action. The diminished ascorbate level at all examined times may play a crucial role in BTH-mediated cell growth regulation. The direct influence of BTH on lipid metabolism should be also taken into consideration. 相似文献
82.
The aim of study was to estimate how the deadwood of different tree species in various stages of decomposition releases dissolved organic carbon (DOC) and total nitrogen concentration. The deadwood of seven species (Common alder, Common aspen, Common ash, Silver fir, Norway spruce, Common hornbeam, and Silver birch) were selected. Three logs from each species in the third, fourth, and fifth decay classes were chosen for analysis. The investigation was carried out in Czarna Rózga Reserve in Central Poland. The leachate from deadwood was collected in lysimeters. Concentrations of total carbon (TC), inorganic carbon (IC), total organic carbon (TOC), and total nitrogen (TN) were determined. In our investigations, the concentration of TOC measure in filtered water samples was equal to DOC. Additionally, pH and electrical conductivity (EC) values were determined in water samples. The results confirmed the importance of the wood species and the stage of decomposition on the concentration of DOC and TN. Significant differences in the concentration of DOC and TN in leachates released between coniferous and deciduous species were noted. Most DOC and TN were released from decomposing hornbeam and aspen wood, the least DOC, and TN were released into the soil from coniferous species, especially the spruce. 相似文献
83.
Walkiewicz Anna Brzezińska Małgorzata Wnuk Ewa Jabłoński Bartosz 《Journal of Soils and Sediments》2020,20(3):1231-1240
Journal of Soils and Sediments - Several studies related to CH4 cycling focus on the effect of elevated atmospheric CO2 levels on soil methanogenesis and methanotrophy. However, periodically... 相似文献
84.
Journal of Plant Diseases and Protection - In its sexual stage, the fungus Epichloë typhina (Ascomycetes: Clavicipitaceae) is a pathogen that causes choke disease in many grass species. It... 相似文献
85.
The number of Enterobacteriaceae, with particular attention given to the presence of Escherichia coli and Klebsiella pneumoniae, was determined in hospital effluents and municipal wastewater after various stages of purification. The emission of these microorganisms to the ambient air near wastewater treatment plant (WWTP) facilities and to the river water, which is a receiver of the WWTP effluent, was also studied using fluorescence in situ hybridization (FISH) and cultivation methods. The number of Enterobacteriaceae determined by cultivation and fluorescence methods in different kinds of sewage sample ranged from 0.5?×?10(3) to 2.9?×?10(6)?CFU/ml and from 2.2?×?10(5) to 1.3?×?10(8) cells/ml, respectively. Their removal rates during treatment processes were close to 99?%, but the number of these bacteria in the WWTP outflow was quite high and ranged from 5.9?×?10(3) to 3.5?×?10(4)?CFU/ml and from 1.1?×?10(5) to 6.1?×?10(5) cells/ml, respectively. In the river water and the air samples, the number of Enterobacteriaceae was also high and ranged from 4.1?×?10(3) to 7.9?×?10(3)?CFU/ml and from 3 to 458?CFU/m(3), respectively. The numbers of these microorganisms obtained from fluorescence and cultivation methods were statistically and significantly correlated; however, the analysis of the studied samples indicated that the FISH method gave values up to 10(3)-fold times greater than those obtained by the cultivation method. From a sanitary point of view, this means that the number of viable fecal bacteria is systematically underestimated by traditional culture-based methods. Thus, the FISH proves to be a method that could be used to estimate bacterial load, particularly in air samples and less contaminated river water. 相似文献
86.
87.
Purpose
The intensive development of nanotechnology raises a question of the potential consequences of the presence of nanoparticles (NPs) in the different components of the environment, including sediments. The aim of this study was to evaluate the toxicity of nanoparticles of ZnO and Ni and their bulk counterparts in bottom sediments (SD1, SD2) with different properties collected from the Vistula River in Poland.Materials and methods
Sediment samples with NPs at a concentration of 100 mg kg?1 were incubated for 17 months in the dark or under a photoperiod of 12 h light/12 h dark. The Microtox® (bacteria, Vibrio fischeri) and OSTRACODTOXKIT F? (ostracods, Heterocypris incongruens) tests were used to evaluate toxicity. In addition, the contents of Zn and Ni were determined in extracts (H2O and CaCl2) of the bottom sediments.Results and discussion
The Zn concentration was much lower in the SD1 sediment with the addition of NPs/bulk particles (30–230 μg kg?1) compared to the SD2 sediment (280–1140 μg kg?1). The toxicity of ZnO and Ni was determined by the type of bottom sediment and the parameter studied. Both nano- and bulk-ZnO and Ni caused the mortality of H. incongruens at a level of 13.3–53.3 %. The influence of ZnO and Ni on the growth of H. incongruens was observed to be the opposite. ZnO resulted in growth stimulation, while Ni resulted in growth inhibition of H. incongruens. Both ZnO and Ni stimulated V. fisheri luminescence. In most cases, the incubation of ZnO and Ni under the photoperiod increased the toxicity or decreased the stimulation of V. fisheri bioluminescence and H. ingongruens growth compared to the dark-incubated sediments.Conclusions
The study provides new and important information on the ecotoxicological effects of ZnO and Ni nanoparticles in different sediments and under various environmental conditions that may be useful for the risk assessment of this new group of contaminants.88.
In order to better understand Cu behaviour in the submontane, eutrophic Dobczyce dam Reservoir (southern Poland), speciationmeasurements of Cu in the water and the sediment were conducted. To investigate the partitioning of Cu in the main components ofthe sediment, a scheme of VI-step sequential extraction was used.In addition, other physical and chemical parameters of the water,such as temperature, pH, dissolved O2, nutrients, and suspended particulate matter were determined. Copper content in the water and the sediment was low (1.1–7.4 μg L-1 and 5.5–45.4 μg g-1, respectively). In the water Cu was usually present in the dissolved state (with the exception ofthe near-bottom water). This was probably the main reason of itssmall accumulation (cumulation coefficient K = 10687.5) in the sediment of the Dobczyce Reservoir. The seasonal variations inCu contents in the dissolved and particulate phases as well as observed correlations with the physico-chemical parameters of thewater are discussed. In the sediment Cu occurred mainly in astrongly bound form. Most Cu found there was in the moderatelyreducible phase and residual. Therefore, copper (re-)mobilization from the sediment to the water was probably not of importance. 相似文献
89.
Mats Aastrup Jacob Johnson Ewa Bringmark Iage Bringmark Åke Iverfeldt 《Water, air, and soil pollution》1991,56(1):155-167
To contribute to the understanding of Hg flow to forest lakes the storage of Hg in the soil of a catchment was quantified,
the transport of Hg from the recharge area to the discharge area was studied and a mass balance for different soil horizons
was calculated. The transport of Hg in soil, ground and stream water was estimated using water flows from a hydrological model
and by determining Hg in water sampled with a clean procedure. The estimate for the annual Hg flux out of the till overburden
in the catchment was 3.4 g km−2. The annual flux was reduced to 1.3 g km−2 in the stream, indicating interception in a lake. The transport was predominantly taking place in the upper 50 cm of the
soil. The storage of Hg in the soil was 8.8 kg km−2, which is large compared to the flux. A net accumulation, amounting to 80% of the Hg deposition, is almost entirely located
to the nor layer. 相似文献
90.
Isolation and antihypertensive effect of angiotensin I-converting enzyme (ACE) inhibitory peptides from spinach Rubisco 总被引：2，自引：0，他引：2
Yang Y Marczak ED Yokoo M Usui H Yoshikawa M 《Journal of agricultural and food chemistry》2003,51(17):4897-4902
Four new inhibitory peptides for angiotensin I-converting enzyme (ACE), that is, MRWRD, MRW, LRIPVA, and IAYKPAG, were isolated from the pepsin-pancreatin digest of spinach Rubisco with the use of HPLC. IC(50) values of individual peptides were 2.1, 0.6, 0.38, and 4.2 microM, respectively. MRW and MRWRD had an antihypertensive effect after oral administration to spontaneously hypertensive rats. Maximal reduction occurred 2 h after oral administration of MRW, whereas MRWRD showed maximal decrease 4 h after oral administration at doses of 20 and 30 mg/kg, respectively. IAYKPAG also exerted antihypertensive activity after oral administration at the dose of 100 mg/kg, giving a maximum decrease 4 h after oral administration. IAYKP, IAY, and KP, the fragment peptides of IAYKPAG, also exerted antihypertensive activity. LRIPVA [corrected] did not show any antihypertensive effect at a dose of 100 mg/kg despite its potent ACE-inhibitory activity. 相似文献