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111.
Biogeochemical mass-balances (C, N, P, Si) in three large reservoirs of the Seine Basin (France) 总被引:7,自引:0,他引:7
Three major reservoirs (Marne, Seine and Aube), situated in the upstream basin of the river Seine represent a storage capacity of 800 106 m3. In order to quantify the possible role of these reservoirs as a sink or source of nutrients and organic matter for the river system, an input/output mass-balance of suspended matter, organic carbon, inorganic nitrogen forms, phosphorus and reactive silica was established, providing reliable estimates of their retention/elimination and export. The study was carried out over 3 years (1993, 1994 and 1995) in differing hydrological conditions. The retention times varied from 0.3 to 0.8 year, depending on the reservoir and the year, but was longer in 1993 that was a drier year than 1994 and 1995, hydrologically quite similar.Regarding retention (or elimination) and export, the behaviour of the three studied reservoirs was similar. A clear loss or retention of nitrogen, phosphorus and silica was observed in the reservoirs and represented about 40% of the incoming flux of nitrate, 50% of silica, and 60% of phosphate. The retention was lower for total phosphorus than for phosphate. The reservoirs are also sites of suspended matter deposition except during the decennial drawdown, when suspended matter is exported. For inorganic nitrogen, the average amount of nitrate retained in the Seine basin reservoirs upstream from Paris is 5000 tonnes y–1 that is almost equal to the estimated retention by deposition or denitrification in river channel sediments for the whole drainage network. The retention in the reservoirs represents about 12% of the total flux of nitrate at the outlet of the basin upstream from Paris, and 5% at the mouth of the Seine River.We also calculated inlake C, N, P, Si budgets on the basis of direct process measurements. Measurements of planktonic primary and bacterial activity production led to annual net production of 4200 and 580 tonnes of carbon, respectively. A reasonable value (450 tonnes of carbon) of grazing was calculated. Corresponding N, P, Si fluxes were drawn from appropriate C:N:P:Si ratios. Benthic fluxes were measured with bell jars. The retention of P and Si represents a small fraction of important internal fluxes of phytoplanktonic uptake and recycling, while inorganic nitrogen retention depends mostly on benthic denitrification. The behaviour of P and Si differs in that P is mainly recycled in the water column, while Si dissolution occurs at the sediment interface. Nitrogen is recycled in both the planktonic and the benthic phase. 相似文献
112.
Fermentation of biomass-generated producer gas to ethanol 总被引:3,自引:0,他引:3
Datar RP Shenkman RM Cateni BG Huhnke RL Lewis RS 《Biotechnology and bioengineering》2004,86(5):587-594
The development of low-cost, sustainable, and renewable energy sources has been a major focus since the 1970s. Fuel-grade ethanol is one energy source that has great potential for being generated from biomass. The demonstration of the fermentation of biomass-generated producer gas to ethanol is the major focus of this article in addition to assessing the effects of producer gas on the fermentation process. In this work, producer gas (primarily CO, CO(2), CH(4), H(2), and N(2)) was generated from switchgrass via gasification. The fluidized-bed gasifier generated gas with a composition of 56.8% N(2), 14.7% CO, 16.5% CO(2), 4.4% H(2), and 4.2% CH(4). The producer gas was utilized in a 4-L bioreactor to generate ethanol and other products via fermentation using a novel clostridial bacterium. The effects of biomass-generated producer gas on cell concentration, hydrogen uptake, and acid/alcohol production are shown in comparison with "clean" bottled gases of similar compositions for CO, CO(2), and H(2). The successful implementation of generating producer gas from biomass and then fermenting the producer gas to ethanol was demonstrated. Several key findings following the introduction of producer gas included: (1) the cells stopped growing but were still viable, (2) ethanol was primarily produced once the cells stopped growing (ethanol is nongrowth associated), (3) H(2) utilization stopped, and (4) cells began growing again if "clean" bottled gases were introduced following exposure to the producer gas. 相似文献
113.
Isabelle E. J. A. Fran?ois Anna Bink Jo Vandercappellen Kathryn R. Ayscough Alexandre Toulmay Roger Schneiter Elke van Gyseghem Guy Van den Mooter Marcel Borgers Davy Vandenbosch Tom Coenye Bruno P. A. Cammue Karin Thevissen 《The Journal of biological chemistry》2009,284(47):32680-32685
Azoles inhibit ergosterol biosynthesis, resulting in ergosterol depletion and accumulation of toxic 14α-methylated sterols in membranes of susceptible yeast. We demonstrated previously that miconazole induces actin cytoskeleton stabilization in Saccharomyces cerevisiae prior to induction of reactive oxygen species, pointing to an ancillary mode of action. Using a genome-wide agar-based screening, we demonstrate in this study that S. cerevisiae mutants affected in sphingolipid and ergosterol biosynthesis, namely ipt1, sur1, skn1, and erg3 deletion mutants, are miconazole-resistant, suggesting an involvement of membrane rafts in its mode of action. This is supported by the antagonizing effect of membrane raft-disturbing compounds on miconazole antifungal activity as well as on miconazole-induced actin cytoskeleton stabilization and reactive oxygen species accumulation. These antagonizing effects point to a primary role for membrane rafts in miconazole antifungal activity. We further show that this primary role of membrane rafts in miconazole action consists of mediating intracellular accumulation of miconazole in yeast cells. 相似文献
114.
Fabio Orlandi Herminia Garcia-Mozo Carmen Galán Bruno Romano Consuelo Diaz de la Guardia Luis Ruiz Maria del Mar Trigo Eugenio Dominguez-Vilches Marco Fornaciari 《International journal of biometeorology》2010,54(2):151-163
The aim of this study was to investigate the main climatic and biological trends related to olive flowering in central-southern
Italy compared to those in Andalusia, Spain. Results since 1982 were compared for the two long-series monitoring areas of
Cordoba and Perugia, and since 1992–1999 for the short-series areas. The relationship between climatic trends and the biological
response of the olive, a widespread culture in the Mediterranean basin, were investigated. An aerobiological method involving
capturing pollen released into the atmosphere was utilised as a bioindicator of flowering phenology. The study results confirm
the strong relationship between flowering periods and spring temperature trends for the olive. Temperature during March, April
and May was the parameter most related to flowering date in the study areas, particularly in Italy. In some cases we found
a significant correlation between flowering and past autumn temperatures, probably due to their effect on floral bud dormancy
induction, but this phenomenon appeared to be of minor importance in the studied areas. The phenological trend results show
the continuous advance of flowering dates to the late 1990s, followed by a relatively stationary time series related to a
short-term temperature fluctuation in the Mediterranean area. This latter period probably represents a mesoscale event forced
by a macroscale event—the North Atlantic Oscillation. The results reveal that the trend towards increased temperatures, and
the consequent flowering advance of some species, indicated some years ago is nowadays not as clear as was expected and should
be confirmed over the next few years in the Mediterranean areas under investigation. 相似文献
115.
Abbas F Morellet N Hewison AJ Merlet J Cargnelutti B Lourtet B Angibault JM Daufresne T Aulagnier S Verheyden H 《Oecologia》2011,167(2):401-411
Forest fragmentation may benefit generalist herbivores by increasing access to various substitutable food resources, with
potential consequences for their population dynamics. We studied a European roe deer (Capreolus capreolus) population living in an agricultural mosaic of forest, woodlots, meadows and cultivated crops. We tested whether diet composition
and quality varied spatially across the landscape using botanical analyses of rumen contents and chemical analyses of the
plants consumed in relation to landscape metrics. In summer and non-mast winters, roe deer ate more cultivated seeds and less
native forest browse with increasing availability of crops in the local landscape. This spatial variation resulted in contrasting
diet quality, with more cell content and lower lignin and hemicellulose content (high quality) for individuals living in more
open habitats. The pattern was less marked in the other seasons when diet composition, but not diet quality, was only weakly
related to landscape structure. In mast autumns and winters, the consumption of acorns across the entire landscape resulted
in a low level of differentiation in diet composition and quality. Our results reflect the ability of generalist species,
such as roe deer, to adapt to the fragmentation of their forest habitat by exhibiting a plastic feeding behavior, enabling
them to use supplementary resources available in the agricultural matrix. This flexibility confers nutritional advantages
to individuals with access to cultivated fields when their native food resources are depleted or decline in quality (e.g.
during non-mast years) and may explain local heterogeneities in individual phenotypic quality. 相似文献
116.
A core eco‐evolutionary aim is to better understand the factors driving the diversification of functions in ecosystems. Using phylogenetic, trophic, and functional information, we tested whether trophic habits (i.e. feeding guilds) affect lineage and functional diversification in two major radiations of reef fishes. Our results from wrasses (Labridae) and damselfishes (Pomacentridae) do not fully support the ‘dead‐end’ hypothesis that specialisation leads to reduce speciation rates because the tempo of lineage diversification did not substantially vary among guilds in both fish families. Our findings also demonstrate a tight relationship between trophic habits and functional roles held by fish in reef ecosystems, which is not associated with a variation in the tempo of functional diversification among guilds. By illustrating the pivotal importance of the generalist feeding strategy during the evolutionary history of reef fishes, our study emphasises the role of this feeding guild as a reservoir for future diversity. 相似文献
117.
Steven Collins Njonte Wouamba Gervais Mouth Happi Michel Nguiam Pouofo Joseph Tchamgoue Jean‐Bosco Jouda Frida Longo Bruno Ndjakou Lenta Norbert Sewald Simeon Fogue Kouam 《化学与生物多样性》2020,17(9)
An extensive phytochemical study of the aerial parts of Vernonia guineensis Benth. (Asteraceae) led to the isolation of a new flavone, vernoguinoflavone and a naturally isolated glycerol ester, eicosanoic acid 2‐hydroxy‐1,3‐propanediyl ester, together with eighteen known secondary metabolites including quercetin, luteolin, vernopicrin, vernomelitensin, β‐amyrin, oleanolic acid, ursolic acid, lupeol, betulinic acid, β‐carotene, a mixture of stigmasterol and β‐sitosterol, β‐sitosterol‐3‐O‐β‐D‐glucoside, 2,3‐dihydroxypropyl heptacosanoate, pentacosanoic acid, docosan‐1‐ol, tritriacontan‐1‐ol, and heptatriacontan‐1‐ol. Eleven compounds are reported herein for the first time from this species. The structures of these compounds were elucidated on the basis of extensive spectroscopic analyses, particularly 1D and 2D NMR, and HR‐ESI‐MS and by comparison of their data with those reported in the literature. The crude extract, fractions and some isolated compounds were evaluated for their antibacterial activity against Gram‐negative bacteria: Escherichia coli (ATCC 25922), Shigella flexineri (NR 518), Salmonella muenchen, Salmonella typhimurium and Salmonella typhi (ATCC 19430). All the tested compounds demonstrated inhibitory activities against the tested enteric bacteria with MIC values ranging from 3.12 to 100 μg/ml. Three flavonoids isolated from the most active fraction demonstrated the best bioactivities against Escherichia coli, Salmonella muenchen and Salmonella typhimurium with MIC values ranging from 3.12 to 25 μg/mL. 相似文献
118.
Bruno Resühr 《Protoplasma》1935,24(1):531-586
Ohne Zusammenfassung 相似文献
119.
Bruno Kieffer Patrice Koehl Serge Plaue Jean-François Lefèvre 《Journal of biomolecular NMR》1993,3(1):91-112
Summary We have investigated the dynamics and structural behaviour of two antigenic peptides using 1H NMR. The two cyclic peptides mimic the antigenic site A of influenza haemagglutinin protein; they only differ in the way they were cyclized and in the size of their respective linkers. Homonuclear relaxation parameters extracted from a complete NOE matrix were interpreted in terms of local dynamics. A set of distance constraints was deduced from these parameters which allowed 3D models to be constructed using distance geometry. NOE back-calculation was used to check the validity of the final models. Strong variations of internal motion amplitude have been found in both peptides along their backbone. Motions with high amplitudes have been localized in the Gly-Pro-Gly sequence which forms a -turn in both structures.Abbreviations DSS
3-(trimethylsilyl)-1-propanesulfonic acid
- D-loop
aspartic acid loop
- ELISA
enzyme-linked immunoabsorbent assay
- f.i.d
free induction decay
- HOHAHA
homonuclear Hartmann-Hahn spectroscopy
- HPLC
high pressure liquid chromatography
- K-loop
lysine loop
- NMR
nuclear magnetic resonance
- NOE
nuclear Overhauser enhancement
- NOESY
nuclear Overhauser enhancement spectroscopy
- r.m.s.d.
root-mean-square deviation of atomic positions 相似文献
120.
Sileshi Belew Mestawet Getachew Sultan Suleman Tesfaye Mohammed Habetewold Deti Matthias D'Hondt Evelien Wynendaele Zeleke Mekonnen Jozef Vercruysse Luc Duchateau Bart De Spiegeleer Bruno Levecke 《PLoS neglected tropical diseases》2015,9(9)
BackgroundThere is a worldwide upscale in mass drug administration (MDA) programs to control the morbidity caused by soil-transmitted helminths (STHs): Ascaris lumbricoides, Trichuris trichiura and hookworm. Although anthelminthic drugs which are used for MDA are supplied by two pharmaceutical companies through donation, there is a wide range of brands available on local markets for which the efficacy against STHs and quality remain poorly explored. In the present study, we evaluated the drug efficacy and quality of two albendazole brands (Bendex and Ovis) available on the local market in Ethiopia.Conclusion/SignificanceThe study revealed that differences in efficacy between the two brands of albendazole (ABZ) tablets against hookworm are linked to the differences in the in-vitro drug release profile. Differences in uptake and metabolism of this benzimidazole drug among different helminth species may explain that this efficacy difference was only observed in hookworms and not in the two other species. The results of the present study underscore the importance of assessing the chemical and physicochemical quality of drugs before conducting efficacy assessment in any clinical trials to ensure appropriate therapeutic efficacy and to exclude poor drug quality as a factor of reduced drug efficacy other than anthelminthic resistance. Overall, this paper demonstrates that “all medicines are not created equal”. 相似文献