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91.
Microbial processes were investigated in the soil of a declining, more eutrophic (Romberk West) and a healthy looking, less eutrophic (Romberk East) freshwater reed stand. Soil was sampled monthly from June to September 1997. Glucose induced carbon dioxide (CO2) production in oxic and anoxic conditions, methane (CH4) production, nitrification and denitrification activities were measured in laboratory conditions in suspensions prepared from homogenised soil samples. Within a stand the proportion of anaerobic (as opposed to aerobic) microbial activity was greatest in June. Potential methanogenesis was highest in June and decreased later in both stands. Methane production was approximately the same in June at both stands but it was higher at Romberk East than at Romberk West stand in later months. Denitrifying activity was higher in August than July at both stands. Nitrifying activity was undetectable at both stands over the entire study period. Generally Romberk West was more anaerobic than Romberk East, with lower redox potential, higher amounts of oxygen-consuming organic matter and a lower ratio of CO2 production in oxic conditions to CO2 production in anoxic conditions. Microbial activity was apparently restricted at Romberk West stand in comparison to Romberk East. The shift from aerobic to anaerobic microbial metabolism and a coinciding restriction of metabolic activities at Romberk West are thought to be indicative of a strengthened oxygen stress in the soil, associated with accumulation of metabolites toxic to both the microorganisms and the reed. Possible links between eutrophication, microbial characteristics and reed performance are discussed. 相似文献
92.
Wheat plants were grown from sowing to day 18 in 26-dm3 chambers at three different CO2 concentrations: 150 (-CO2), 350 (C, control), 800 (+CO2) mol mol-1. Afterwards, plants of the three variants were grown at the same natural CO2 concentration. Plant characteristics were measured just before the transfer (0 days after CO2 treatment, DAT), and at 5 – 8 DAT on the 1st leaf, and at 12 – 22 DAT on the 4th leaf. Decreased or increased CO2 concentrations caused acclimations which persisted after transplantation to natural CO2 concentration. At 5 – 8 DAT, stomatal density, stomatal conductance (gs), CO2 saturated net photosynthetic rate (PNsat0), radiation saturated net photosynthetic rate (PNsat1), and carboxylation efficiency () were higher in -CO2 plants and lower in +CO2 plants than in C plants. As compared with C plants, the photochemical efficiency () was lower in -CO2 and higher in -CO2 plants, however, chlorophyll (Chl) a, Chl b, Chl a–b and carotenoid contents were lower in both -CO2 and +CO2 plants. On the 4th leaf, which emerged on plant after finishing CO2 treatments, at 12 – 22 DAT, no differences in stomatal density and g, between treatments were observed. In -CO2 plants, pigment content and PNsat0 were higher, was lower, and PNsat1 and were not different from C plants. In contrast, in +CO2 plants, pigment content, PNsat1 and were lower, and PNsat0 and were unchanged. Leaf area, dry mass, and tiller development increased in +CO2 plants and decreased in -CO2 plants. In the interval between 8 and 22 DAT, lower net assimilation rate in +CO2 than in -CO2 plants was observed. 相似文献
93.
Accumulation of the pathogenesis-related (PR) proteins localised in intercellular spaces of barley primary leaves, chlorophyll
content, structure of chloroplasts, and photosynthesis were examined during natural and in vitro induced leaf senescence (cultivation
of whole plants in the dark or detached leaves under nutrient deficiency). Some of PR proteins accumulated during natural
senescence, but their accumulation pattern was different from those of pathogen-induced as well as during in vitro-induced
senescence, which indicate different molecular bases of these processes. Photosynthetic rate and chlorophyll content indicate
that natural senescence of barley primary leaves began from 15th day after sowing. In 35-d-old first leaves, the chloroplasts
showed typical characteristics of senescence as significant decrease of size, greater grana, and prominent plastoglobuli.
The chloroplasts contained more grana under in vitro induced senescence and they had reduced length in the dark. Correspondingly,
accumulation of PR proteins was detectable on about the 15th day but the content of some PR proteins increased in later stages
of senescence.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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96.
Characterization of a model cyanobacterium Synechocystis sp. PCC 6803 autotrophic growth in a flat‐panel photobioreactor 下载免费PDF全文
Tomáš Zavřel Maria A. Sinetova Diana Búzová Petra Literáková Jan Červený 《Engineering in Life Science》2015,15(1):122-132
We characterized the photoautotrophic growth of glucose‐tolerant Synechocystis sp. PCC 6803 in a flat‐panel photobioreactor running on a semicontinuous regime under various lights, temperatures, and influx carbon dioxide concentrations. The maximum reached growth rate was 0.135 h?1, which corresponds to a doubling time of 5.13 h—a growth speed never reported for Synechocystis before. Saturating red light intensity for the strain was 220–360 μmol(photons) m?2 s?1, and we did not observe any photoinhibition up to 660 μmol(photons) m?2 s?1. Synechocystis was able to grow under red light only; however, photons of wavelengths 405–585 and 670–700 nm further improved its growth. Optimal growth temperature was 35°C. Below 32°C, the growth rates decreased linearly with temperature coefficient (Q10) 1.70. Semicontinuous cultivation is known to be efficient for growth characterization and optimization. However, the assumption of correct growth rates calculation—culture exponential growth—is often not fulfilled. The semicontinuous setup in this study was operated as a turbidostat. Accurate online OD measurements with high time‐resolution allowed fast and reliable growth rates determination. Repeating diluting frequencies (up to 18 dilutions per day) were essential for rapid growth stability evaluation. The presented setup provides improvement to previously published semicontinuous characterization strategies by decreasing experimental time requirements and maintaining the culture in exponential growth phase throughout the entire characterization procedure. 相似文献
97.
98.
The wild boar is a native animal species of the Czech Republic that has significantly increased its population density in recent years. Objective methods of population density estimation are required to inform the intensity of regulation needed for the sustainable management of the wild boar. Population estimation and regulation of the abundance of the wild boar are problematic in comparison to those of other ungulates, and the only widely used method of control is intensive hunting. The purpose of this study was to test if faecal pellet group (FPG) counting was a reliable method of wild boar population censusing in a forest environment. The density of wild boars was evaluated in an area of 22.56 km2, circumscribed by both natural and man-made barriers that restrict wild boar migration. As it is essential for proper application of FPG count methods, a separate trial was carried out to determine the daily defecation rate of wild boars. The distribution of faeces in different types of habitat in a forest environment was tested. As the period of faeces accumulation fell within the intensive hunting season, the result is biased by the fact that the calculation includes FPGs produced by animals removed from the population through hunting during winter. The average daily defecation rate of adults and piglets was 4.29 and 5.82, respectively. The corrected (without shot animals) average density of wild boars in the study area estimated by the FPG count at the time of the census was 6.08 individuals (ind.)/km2. We have confirmed that an FPG count conducted in winter is applicable for estimation of wild boar abundance on a forested area. 相似文献
99.
Planktonic crustaceans are traditionally identified based on morphological and morphometric characters. However, such characters may be hardly distinguishable and often overlap between species. A probability of misidentification is thus relatively high. Molecular techniques may increase the accuracy of identification if appropriate markers are used. Aim of our work was to develop a simple molecular procedure enabling discrimination between four species of Simocephalus occurring in Europe. PCR-RFLP technique proved to be suitable for such discrimination. Within the 709 bp fragment of mitochondrial cytochrome c oxidase subunit 1 gene we found unique combinations of restriction sites of the BbsI and SacI enzymes for Simocephalus vetulus, S. exspinosus, S. serrulatus and S. congener. PCR products of samples from several locations in Slovakia were digested with the two enzymes and electrophoresed on an agarose gel. The restriction patterns were clearly visible and easily distinguishable. This method is applicable for identifying the four species in any life-stage. Considering its simplicity and cost-effectiveness it can be widely used as a diagnostic tool for discriminating between Simocephalus species with overlapping morphologic characters. 相似文献
100.
Petr Niederhafner Lucie Bednárová Miloš Buděšínský Martin Šafařík Sille Ehala Jan Ježek Lenka Borovičková Vladimír Fučík Václav Čeřovský Jiřina Slaninová 《Amino acids》2010,39(5):1553-1561
The recently described antimicrobial peptide melectin (MEP, GFLSILKKVLPKVMAHMK-NH2) exhibits high antimicrobial activity against Gram-positive and Gram-negative bacteria. Here we describe the synthesis and biological activities of 23 new analogues of MEP. We studied the influence of dimerization and tetramerization (MAP-constructs of MEP) on the antimicrobial and hemolytic activities, as well as the role of Met in positions 14 and 17 of the peptide chain. Oxidation of the Met to Met(O) and Met(O2) decreases antimicrobial activity of all tested bacteria if the peptide is in the monomeric form, however, only to Staphylococcus aureus if in the form of dimer or tetramer. Dimerization and tetramerization increase the undesirable hemolytic activity of the peptides. Interestingly, substitution of Leu for Val in position 6 leads to the decrease of hemolytic activity. Introduction of the isosteric amino acid Nle into positions 14 or 17 or both leads to slight increase of hemolytic activity under preservation of high antimicrobial activities. Unfortunately, dimerization again leads to an increase of hemolytic activity. 相似文献