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101.
Leone S Izzo V Sturiale L Garozzo D Lanzetta R Parrilli M Molinaro A Di Donato A 《Carbohydrate research》2004,339(16):2657-2665
A minor oligosaccharide fraction was isolated after complete de-acylation of the lipooligosaccharide extracted from Pseudomonas stutzeri OX1. The full structure of this oligosaccharide was obtained by chemical degradation, NMR spectroscopy and MALDI-TOF MS spectrometry. These experiments showed the presence of two novel oligosaccharides (OS1 and OS2): [structure: see text] where R=(S)-Pyr(-->4,6) in OS1 and alpha-Rha-(1-->3) in OS2. All sugars are D-pyranoses, except Rha, which is L-pyranose. Hep is L-glycero-D-manno-heptose, Kdo is 3-deoxy-D-manno-oct-2-ulosonic acid, Pyr is pyruvic acid, P is phosphate. 相似文献
102.
Benedetti S Rinalducci S Benvenuti F Francogli S Pagliarani S Giorgi L Micheloni M D'Amici GM Zolla L Canestrari F 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2006,833(1):12-18
Aphanizomenon flos-aquae (AFA) is a blue-green alga and represents a nutrient-dense food source. In this study the presence of phycocyanin (PC), a blue protein belonging to the photosynthetic apparatus, has been demonstrated in AFA. An efficient method for its separation has been set up: PC can be purified by a simple single step chromatographic run using a hydroxyapatite column (ratio A620/A280 of 4.78), allowing its usage for health-enhancing properties while eliminating other aspecific algal components. Proteomic investigation and HPLC analysis of purified AFA phycobilisomes revealed that, contrary to the well-characterized Synechocystis and Spirulina spp., only one type of biliprotein is present in phycobilisomes: phycocyanins with no allo-phycocyanins. Two subunit polypeptides of PC were also separated: the beta subunit containing two bilins as chromophore and the alpha subunit containing only one. 相似文献
103.
Alessandro Balestrieri Luigi Remonti Nicola Ferrari Angelo Ferrari Tatiana Lo Valvo Serena Robetto Riccardo Orusa 《European Journal of Wildlife Research》2006,52(3):196-201
Between 2001 and 2004, 229 foxes, 36 stone martens and 48 badgers from the western Italian Alps were examined for sarcoptic mange and for gastrointestinal helminths to investigate their prevalence and geographical distribution and to point out the existence of potential interactions among them. Sarcoptic mange was observed in 25.3±2.8% SE of foxes and in 5.6±3.8% SE of stone martens, while no badger was found infected. Helminths belonged to Cestoidea Cyclophillidea (3.0±1.1% SE), Nematoda Trichurida (Capillaria aerophila and Trichuris vulpis: 6.5±1.6% SE; Trichinella britovi: 3.0±1.1% SE), Ascaridida (12.2±2.2% SE) and Strongylida (6.9±1.7% SE). Sarcoptic mange infection and the presence of helminths proved to be associated, with mangy foxes showing significantly higher prevalence of both cestode and nematode (particularly Ascaridida) worms. Moreover, considering three clusters of parasites (S. scabiei, nematodes and cestodes), more foxes than expected hosted simultaneously 2 and 3 taxa. These evidences suggest the existence of some kind of interaction, whose modalities and implications are discussed in this paper. 相似文献
104.
105.
106.
Roberto Bertoni Cristiana Callieri Gianluca Corno Serena Rasconi Emanuele Caravati Mario Contesini 《Hydrobiologia》2010,644(1):279-287
We analysed the long-term dynamics (1980–2007) of hypolimnetic and epilimnetic bacterial abundances and organic carbon concentrations,
both dissolved (DOC) and particulate (POC), in the deep holo-oligomictic Lake Maggiore, included in the Southern Alpine Lakes
Long-Term Ecological Research (LTER) site. During the 28 years of investigation, bacterial abundance and POC concentrations
did not decrease with declining phosphorus concentrations, while DOC concentrations showed a pronounced decrease in the epi-
and hypolimnion. We used the annual mean total lake heat content and total annual precipitation as climate-related variables,
and in-lake total phosphorus as a proxy for trophic state. The model (forward stepwise regression, FSR) showed that reduced
anthropogenic pressure was more significant than climate change in driving the trend in DOC concentrations. Bacterial dynamics
in the hypolimnion mirrored the fluctuations observed in the epilimnion, but average cell abundance was three times lower.
The FSR model indicates that bacterial number variability was dependent on POC in the epilimnion and DOC in the hypolimnion.
In the hypolimnion, cell biovolumes for rod and coccal morphotypes were significantly larger than in the epilimnion. 相似文献
107.
We have synthesized four 6-thio pseudo glycolipid analogues and assessed how two of them self-assembled on a gold surface. These structures were designed as candidate tethers molecules to anchor bilayer lipid membranes on gold. 6-Deoxy-6-thiogalactose was chosen to anchor the macromolecule to the gold and define an aqueous zone at the gold surface. A long alkane chain (C-12 or C-18) linked to the anomeric position of the sugar residue was chosen to anchor a bilayer lipid membrane. The linkage between the carbohydrate and the hydrophobic chains is either a glycosidic bond or a 1,4-disubstituted triazole formed by copper(I)-catalysed alkyne-azide cycloaddition (CuAAC) of the propargyl glycoside with azido-dodecane and azido-octadecane. We are expecting that the hydrocarbon chains will orient themselves perpendicular to the gold surface and be incorporated into the first leaflet of the bilayer membrane. We have studied self assembled monolayers of the C-12 aglycone analogues on gold using infrared reflection absorption spectroscopy (IRRAS). We compared the results given by the IRRAS experiments to the IR spectra recorded by attenuated total reflection (ATR) spectroscopy on films of the randomly oriented analogues. Our results demonstrate that the C-12 analogues did bind to gold and did orient themselves perpendicular to the gold slide. 相似文献
108.
QM and QM/MM energy calculations have been carried out on an atomic resolution structure of liganded triosephosphate isomerase (TIM) that has an active site proline (Pro168) in a planar conformation. The origin of the planarity of this proline has been identified. Steric interactions between the atoms of the proline ring and a tyrosine ring (Tyr166) on one side of the proline prevent the ring from adopting the up pucker (chi1 is approximately -30 degrees), while the side chain of a nearby alanine (Ala171) forbids the down pucker (chi1 is approximately +30 degrees). To obtain a proline conformation that is in agreement with the experimentally observed planar state, a quantum system of sufficient size is required and should at least include the nearby side chains of Tyr166, Ala171, and Glu129 to provide enough stabilization. It is argued that the current force fields for structure optimization do not describe strained protein fragments correctly. The proline is part of a catalytic loop that closes upon ligand binding. Comparison of the proline conformation in different TIM X-ray structures, indicates that in the closed conformation of TIM the proline is planar or nearly planar, while in the open conformation it is down puckered. This suggests that the planarity possibly plays a role in the overall catalytic cycle of TIM, presumable acting as a reservoir of energy that becomes available upon loop opening. 相似文献
109.
110.
Dolganiuc A Chang S Kodys K Mandrekar P Bakis G Cormier M Szabo G 《Journal of immunology (Baltimore, Md. : 1950)》2006,177(10):6758-6768
IFN-alpha production by plasmacytoid dendritic cells (PDCs) is critical in antiviral immunity. In the present study, we evaluated the IFN-alpha-producing capacity of PDCs of patients with chronic hepatitis C virus (HCV) infection in treatment-naive, sustained responder, and nonresponder patients. IFN-alpha production was tested in PBMCs or isolated PDCs after TLR9 stimulation. Treatment-naive patients with chronic HCV infection had reduced frequency of circulating PDCs due to increased apoptosis and showed diminished IFN-alpha production after stimulation with TLR9 ligands. These PDC defects correlated with the presence of HCV and were in contrast with normal PDC functions of sustained responders. HCV core protein, which was detectable in the plasma of infected patients, reduced TLR9-triggered IFN-alpha and increased TNF-alpha and IL-10 production in PBMCs but not in isolated PDCs, suggesting HCV core induced PDC defects. Indeed, addition of rTNF-alpha and IL-10 induced apoptosis and inhibited IFN-alpha production in PDCs. Neutralization of TNF-alpha and/or IL-10 prevented HCV core-induced inhibition of IFN-alpha production. We identified CD14+ monocytes as the source of TNF-alpha and IL-10 in the HCV core-induced inhibition of PDC IFN-alpha production. Anti-TLR2-, not anti-TLR4-, blocking Ab prevented the HCV core-induced inhibition of IFN-alpha production. In conclusion, our results suggest that HCV interferes with antiviral immunity through TLR2-mediated monocyte activation triggered by the HCV core protein to induce cytokines that in turn lead to PDC apoptosis and inhibit IFN-alpha production. These mechanisms are likely to contribute to HCV viral escape from immune responses. 相似文献