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51.
52.
Euphytica - Foliar application of two spring wheat varieties, Anza and Yecora 70, with RH-531 several days before meiosis in a field experiment almost completely prevented seed development. A... 相似文献
53.
R.D. Vogt H.M. Seip H. Orefellen G. Skotte C. Irgens J. Tyszka 《Water, air, and soil pollution》2001,130(1-4):745-750
Soil water at an acid-sensitive forested catchment in southwestern Poland has been studied for four years. Median base saturation (BS) is only 5% in the podzol B-horizons. Very low pH values in the soil water from the O-horizons (10- and 90 percentiles pH 3.5 and 4.3) increased to a typical median pH in the B-horizons of 4.4, mainly by release of inorganic labile aluminium (Ali). Median concentrations in the B horizons were 3.4mg Ali L?1. Al-soil/soilwater interactions were studied over a large span of sulphate concentrations resulting from both a generally decreasing S-deposition during the last decades and an increase in precipitation during the study period. These changes led sulphate to leach from the mineral soil. Aluminium mobilisation is better described by jurbanite- than by gibbsite solubility. For the soils with aluminium saturation (AlS) >90%, there is a tendency that the concentration of Al3+ decreases less than divalent base cations with a decrease in SO4 2? concentration. This causes the critical load molar ratio (RCL={Al3+}/{Ca2++Mg2+}) to increase with a decrease in the sulphate concentration in soil water, which is not in agreement with a simple cation-exchange model. 相似文献
54.
A. B. S. Poléo E. Lydersen B. O. Rosseland F. Kroglund B. Salbu R. D. Vogt A. Kvellestad 《Water, air, and soil pollution》1994,75(3-4):339-351
The present study is mainly focusing on mortality variations of fish due to changing Alchemistry of mixing zones. An artificial mixing zone was made by pumping water from a limed stream and an acidic tributary into a mixing channel. Atlantic salmon (Salmo salar L.) parr were exposed to the mixed water, limed stream water, and acidic tributary water. Mortality, blood haematocrit and plasma Cl?-concentration were recorded. Neither mortality, nor changes in haematocrit and plasma Cl? were observed when fish were exposed to limed water, while in both acidic and mixed water, mortalities and loss of plasma Cl? were observed. The highest mortality rates were found within the initial part (0 to 20 s) of the mixing zone. Blood haematocrit increased only in fish exposed to acidic tributary water. Our results shows that changes in Al-chemistry and subsequent Al-polymerization occur when acidic tributary water is mixed with limed stream water. We have also demonstrated that the toxicity which can arise in mixing zones are greater than in the original acidic water before mixing. The variations in mortality observed are associated with the quality and quantity of Al-polymerization as well as ageing of the polymers. 相似文献
55.
João Barateiro Diogo Tiago Natal-da-Luz José Paulo Sousa Christian Vogt Carsten Nowak 《Journal of Soils and Sediments》2007,7(6):388-392
Background, Aims, and Scope The springtail Folsomia candida is a commonly used model species in ecotoxicological soil testing. The species reproduces parthenogenetically and, thus,
laboratories use different clonal lineages. In this study, we investigated if genetic divergence between F. candida strains impacts the reaction to chemical stress and may thus affect the outcome of toxicity tests.
Methods In two exposure assays (life-cycle reproduction test and avoidance behaviour test), three laboratory strains of F. candida from Portugal (PTG), Spain (SPN) and Denmark (DNK) were exposed to different concentrations of the reference chemical phenmedipham.
Genetic divergence among strains was estimated based on mitochondrial COI sequence data.
Results No significant differences between tolerance towards phenmedipham exposure were observed in a reproduction test. In contrast,
one strain (SPN) showed a decreased susceptibility to phenmedipham compared to the other strains (PTG and DNK) in the avoidance
assay.
Discussion A phylogenetic tree based on mitochondrial COI sequences revealed clear genetic differentiation between both ‘reaction types’.
Thus, we found a potential lineage dependent stress reaction in avoidance behaviour towards the pesticide.
Conclusions Our findings have implications for the comparability of test results among laboratories. Reproduction tests seem to be more
robust towards interclonal genetic differentiation than avoidance tests.
Recommendations and Perspectives We recommend the use of molecular tools for simple and cost effective genetic characterization of F. candida strains used in chemical avoidance tests. Closer investigations concerning the relation between genetic relatedness and chemical
response will provide a more detailed and comprehensive picture on the role of intraspecific genetic differentiation in stress
tolerance.
ESS-Submission Editor: Prof. Dr. Henner Hollert (henner.hollert@bio5.rwth-aachen.de) 相似文献
56.
In order to gain insight into the community structure and the biodegradative potential of bacteria residing in a BTEX-contaminated field site, with benzene as main pollutant, an investigation strategy with a variety of cultivation-independent and -dependent approaches was undertaken. Based on 16S ribosomal DNA sequence analysis, sampling stations in the center of the pollution plume were found to be dominated by a bacterial consortium affiliated with various members of the class of Proteobacteria and Firmicutes, including different sporulating and non-sporulating sulfate-reducing bacteria and members of the genus Geobacter. Non-polluted samples retrieved from outside the plume revealed several phylotypes which were also observed in the centre of the plume. Bacterial sequences retrieved from the fringe of the plume were dominated by several genera of beta Proteobacteria subclass which were not associated with other phylotypes obtained in this study. All sampling stations were tested positive for catechol 2,3-dioxygenase genes, indicating the presence of microorganisms with the genetic potential degrading aromatic compounds via the meta-cleavage pathway. The groundwater system at the down-gradient edge of the plume was characterized, in contrast to all other sampling stations in the center and outside the plume, by high numbers of cultivable bacteria and cultivable aerobic benzene and toluene degraders. These findings are also in accordance with the investigations based on fluorescent in situ hybridization (FISH) with rRNA-targeted oligonucleotide probes, suggesting the presence of an actively benzene degrading bacterial community of beta Proteobacteria at the fringe of the pollution plume. 相似文献
57.
Olsen E Vogt G Veberg A Ekeberg D Nilsson A 《Journal of agricultural and food chemistry》2005,53(19):7448-7457
Dynamic headspace/gas chromatography-mass spectrometry (GC-MS), front-face fluorescence spectroscopy, and a gas-sensor array technique (electronic nose) have previously detected lipid oxidation in pork back fat or mechanically recovered poultry meat earlier than or at the same time as a sensory panel. The present study was focused on measurement of early lipid oxidation in a more complicated product (freeze-stored, smoked sausages with spices). During the storage time, formation of components contributing to rancid odor and flavor (e.g., hexanal and 1-penten-3-ol) could be monitored with dynamic headspace/GC-MS. The GC-MS data also showed a decrease in 2-furancarboxaldehyde, which could indicate loss of Maillard type components often associated with acidic or meat odor and flavor. The fluorescence spectra were difficult to interpret, probably due to the simultaneous influence from increasing levels of lipid oxidation products and loss of fluorescent Maillard or spice components. The gas-sensor array responses were dominated by signals from, e.g., spice and smoke compounds. 相似文献
58.
Olsen E Vogt G Ekeberg D Sandbakk M Pettersen J Nilsson A 《Journal of agricultural and food chemistry》2005,53(2):338-348
An analytical method that can detect low levels of oxidation in food earlier than a sensory panel would be a valuable tool for food manufacturers as well as research institutes. Two model matrixes, pork back fat and mechanically recovered poultry meat (MRPM), were freeze-stored in air at -20 degrees C for 26 weeks. Peroxide value, thiobarbituric acid reactive substances, volatiles analyzed with dynamic headspace gas chromatography-mass spectrometry (GC-MS) and a gas-sensor array technique (electronic nose), chemiluminescence, and front-face fluorescence were evaluated against sensory analysis with regard to detection of early oxidation and correlation with sensory data. Fluorescence and GC-MS could detect oxidative changes in pork back fat earlier than the sensory panel and the electronic nose at the same time. The three methods were highly correlated with sensory attributes (r = 0.8-0.9). GC-MS gave the best results with regard to detection of small oxidative changes in MRPM. 相似文献
59.
Parakeratosis was diagnosed in 9 Shorthorn beef calves over a 4-year period. When pedigrees of these calves were analyzed, familial associations were strong. Thirty-six coefficients of relationship among all possible combinations of the 9 affected calves ranged from 0.5 to 39.8% and averaged 15.6%. All affected calves were descendants of bull A. Of 9 affected calves, 6 had bull A in their paternal and maternal pedigrees. The 3 remaining affected calves had bull A in their sire's pedigree and were born to 2 full-sib dams. Seemingly, parakeratosis in this Shorthorn herd was hereditary with the mode of inheritance being that of a simple autosomal recessive. 相似文献
60.
Rhenium heptafluoride, ReF(7), is one of only two stable binary compounds MX(7) with a heptacoordinated metal atom M and halide atom X. Its low-temperature crystal structure, as determined by high-resolution powder neutron diffraction, reveals the molecular structure, which has been the subject of speculation and debate for many years. Here it is shown within experimental error that at 1.5 kelvin the lowest energy configuration of ReF(7) has symmetry Cs (m) and is a distorted pentagonal bipyramid. The deviation of the two axial Re-F bonds from collinear and the puckering of the ring of equatorial fluorine atoms are similar to what has been postulated as one of the conformations of the pseudorotational motion observed at higher temperatures. 相似文献