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91.
Per Saris Suvi Taira Ulla Airaksinen Airi Palva Matti Sarvas Ilkka Palva Kate Runeberg-Nyman 《FEMS microbiology letters》1990,68(1-2):143-148
Pertussis toxin (PT) is a major component of today's acellular whooping cough vaccines. The use of acellular vaccines is predicted to increase sharply in the near future. There is therefore a need to produce PT in a way that makes its purification as easy as possible. Our approach was to express all five PT subunits individually in Bacillus subtilis. We have used vectors containing the promoter and signal sequences of the alpha-amylase gene of Bacillus amyloliquefaciens followed by an insert encoding the appropriate PT-subunit. All PT-subunits were secreted and found in the culture supernatant. The level of expression varied considerably: S1 and S5 were produced in large quantities whereas much smaller amounts of S2, S3 and S4 were found. The subunits were also present in the membrane fraction of the respective strains. 相似文献
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93.
Binding of phosphate in sediment accumulation areas of the eastern Gulf of Finland,Baltic Sea 总被引:1,自引:0,他引:1
The relationships between P and components binding P were studied by analysing the concentrations of N, P, Fe, Mn, Ca and Al in sediments and pore water along the estuarine transect of the River Neva in August 1995. The high sediment organic matter concentration resulted in low surface redox potential and high pore-water o-P concentration, whereas the abundance of amphipods resulted in high surface redox potentials and low pore-water o-P concentration. However, despite the variation in sediment organic matter and the abundance of amphipods, very reduced conditions and slightly variable concentrations of Tot-P (0.7–1.1 mg g–1 DW) were observed in the 10–15 cm sediment depth along the estuarine gradient, indicating that the pools of mobile P were largely depleted within the depth of 0–15 cm. Multiple regression analysis demonstrated that organic matter and Tot-Fe concentration of the sediment were closely related to the variation in Tot-P concentration of the sediments (r
2 = 0.817, n=32). In addition, the high total Fe:P ratio suggested that there is enough Fe to bind P in sediments along the estuarine gradient. However, low Fediss concentrations in the pore water of reduced sediment (redox-potential <–50 mV) indicated efficient precipitation of FeS (FeS and FeS2), incapable to efficiently bind P. Consequently, the low Fediss:o-P ratio (< 1) recorded in pore water in late summer implied that Fe3+ oxides formed by diffusing Fediss in the oxic zone of the sediments were insufficient to bind the diffusing o-P completely. The measured high o-P concentrations in the near-bottom water are consistent with this conclusion. However, there was enough Fediss in pore water to form Fe3+ oxides to bind upwards diffusing P in the oxic sediment layer of the innermost Neva estuary and the areas bioturbated by abundant amphipods. 相似文献
94.
Intake of Energy and Protein is Associated with Overweight Risk at Age 5.5 Years: Results from the Prospective TEDDY Study 下载免费PDF全文
Andreas Beyerlein Ulla M. Uusitalo Suvi M. Virtanen Kendra Vehik Jimin Yang Christiane Winkler Mathilde Kersting Sibylle Koletzko Desmond Schatz Carin Andrén Aronsson Helena Elding Larsson Jeffrey P. Krischer Anette‐G. Ziegler Jill M. Norris Sandra Hummel for the TEDDY Study Group 《Obesity (Silver Spring, Md.)》2017,25(8):1435-1441
95.
The diversity and community structure of macrophyte vegetation was studied in 50 boreal lakes forming several upper reaches of lake chains around Lammi, southern Finland. Water chemical parameters and morphometry of the basins were included in a multivariate analysis. Floating-leaved vegetation was the dominant growth form, followed by emergent plants. In downstream lakes, the dominance of floating-leaved macrophytes declined, and emergent species increased in abundance. Species richness was highest in larger lakes, with a wider range of littoral habitats than smaller lakes. Electrical conductivity (range 18–151 mS cm−1, 25 °C) of the water correlated well with patterns in diversity among lakes, but this was not the case for nutrient concentrations. As a whole, morphometrical characteristics of lake basins showed better correlations with vegetation structure than any of the measured chemical parameters. The macrophyte vegetation of neighbouring lake chains differed considerably, depending on the surrounding landscape properties, water quality of the lakes and immigration history of plant species. 相似文献
96.
Niche differentiation in soil horizons, host species and natural nutrient gradients contribute to the high diversity of ectomycorrhizal fungi in boreal forests. This study aims at documenting the diversity and community composition of ectomycorrhizal fungi of Norway spruce ( Picea abies ) and silver birch ( Betula pendula ) seedlings in five most abundant microsites in three Estonian old-growth forests. Undisturbed forest floor, windthrow mounds and pits harboured more species than brown- and white-rotted wood. Several species of ectomycorrhizal fungi were differentially represented on either hosts, microsites and sites. Generally, the most frequent species in dead wood were also common in forest floor soil. Ordination analyses suggested that decay type determined the composition of EcM fungal community in dead wood. Root connections with in-growing mature tree roots from below affected the occurrence of certain fungal species on seedling roots systems in dead wood. This study demonstrates that ectomycorrhizal fungi differentially establish in certain forest microsites that is attributable to their dispersal and competitive abilities. Elevated microsites, especially decayed wood, act as seed beds for both ectomycorrhizal forest trees and fungi, thus affecting the succession of boreal forest ecosystems. 相似文献
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Tedersoo L Jairus T Horton BM Abarenkov K Suvi T Saar I Kõljalg U 《The New phytologist》2008,180(2):479-490
Ectomycorrhizal (ECM) symbiosis is a widespread plant nutrition strategy in Australia, especially in semiarid regions. This study aims to determine the diversity, community structure and host preference of ECM fungi in a Tasmanian wet sclerophyll forest. Ectomycorrhizal fungi were identified based on anatomotyping and rDNA internal transcribed spacer (ITS)-large subunit (LSU) sequence analysis using taxon-specific primers. Host tree roots were identified based on root morphology and length differences of the chloroplast trnL region. A total of 123 species of ECM fungi were recovered from root tips of Eucalyptus regnans (Myrtaceae), Pomaderris apetala (Rhamnaceae) and Nothofagus cunninghamii (Nothofagaceae). The frequency of two thirds of the most common ECM fungi from several lineages was significantly influenced by host species. The lineages of Cortinarius, Tomentella-Thelephora, Russula-Lactarius, Clavulina, Descolea and Laccaria prevailed in the total community and their species richness and relative abundance did not differ by host species. This study demonstrates that strongly host-preferring, though not directly specific, ECM fungi may dominate the below-ground community. Apart from the richness of Descolea, Tulasnella and Helotiales and the lack of Suillus-Rhizopogon and Amphinema-Tylospora, the ECM fungal diversity and phylogenetic community structure is similar to that in the Holarctic realm. 相似文献
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Salo H Aitio O Ilves K Bencomo E Toivonen S Penttilä L Niemelä R Salminen H Grabenhorst E Renkonen R Renkonen O 《Glycobiology》2002,12(3):217-228
The GalNAcbeta1-4GlcNAc determinant (LdN) occurs in some human and bovine glycoconjugates and also in lower vertebrates and invertebrates. It has been found in unsubstituted as well as terminally substituted forms at the distal end of conjugated glycans, but it has not been reported previously at truly internal positions of polylactosamine chains. Here, we describe enzyme-assisted conversion of LdNbeta1-OR oligosaccharides into GlcNAcbeta1-3GalNAcbeta1-4GlcNAcbeta1-OR. The extension reactions, catalyzed by human serum, were modeled after analogous beta3-GlcNAc transfer processes that generate GlcNAcbeta1-3Galbeta1-4GlcNAcbeta1-OR. The newly synthesized GlcNAcbeta1-3GalNAc linkages were unambiguously identified by nuclear magnetic resonance data, including the appropriate long-range correlations in heteronuclear multiple bond correlation spectra. The novel GlcNAcbeta1-3'LdN determinant proved to be a functional acceptor for several mammalian glycosyltransferases, suggesting that human polylactosamines may contain internal LdN units in many distinct forms. The GlcNAcbeta1-3'LdN determinant was unusually resistant toward jackbean beta-N-acetylhexosaminidase; the slow degradation should lead to a convenient method for the search of putative internal LdN determinants in natural polylactosamine chains. 相似文献