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排序方式: 共有195条查询结果,搜索用时 14 毫秒
1.
Górska-Frączek S Sandström C Kenne L Rybka J Strus M Heczko P Gamian A 《Carbohydrate research》2011,346(18):2926-2932
A novel structure of exopolysaccharide from the lactic acid bacteria (LAB) Lactobacillus rhamnosus KL37B, from the human intestinal flora, is described. During the structural investigation of the exopolysaccharide it was found that the repeating unit is a nonasaccharide, which is the largest repeating unit found in LAB exopolysaccharides to date. The polysaccharide material was prepared by TCA extraction of a bacterial cell mass, purified by anion-exchange and gel permeation chromatography and characterized using chemical and enzymatic methods. On the basis of monosaccharide and methylation analysis and also 1D and 2D 1H and 13C NMR spectroscopy the exopolysaccharide was shown to be composed of the following nonasaccharide repeating unit:The physicochemical cell surface study and adhesive properties indicated distinct surface properties of Lactobacillus rhamnosus strain KL37B with high adhesive abilities to Caco-2 cells, hydrophobicity and slime production, in comparison to other Lactobacillus strains used as controls. 相似文献
2.
Jonathan E. Ulmer Eric Morssing Vilén Ramesh Babu Namburi Alhosna Benjdia Julie Beneteau Annie Malleron David Bonnaffé Pierre-Alexandre Driguez Karine Descroix Gilbert Lassalle Christine Le Narvor Corine Sandstr?m Dorothe Spillmann Olivier Berteau 《The Journal of biological chemistry》2014,289(35):24289-24303
Despite the importance of the microbiota in human physiology, the molecular bases that govern the interactions between these commensal bacteria and their host remain poorly understood. We recently reported that sulfatases play a key role in the adaptation of a major human commensal bacterium, Bacteroides thetaiotaomicron, to its host (Benjdia, A., Martens, E. C., Gordon, J. I., and Berteau, O. (2011) J. Biol. Chem. 286, 25973–25982). We hypothesized that sulfatases are instrumental for this bacterium, and related Bacteroides species, to metabolize highly sulfated glycans (i.e. mucins and glycosaminoglycans (GAGs)) and to colonize the intestinal mucosal layer. Based on our previous study, we investigated 10 sulfatase genes induced in the presence of host glycans. Biochemical characterization of these potential sulfatases allowed the identification of GAG-specific sulfatases selective for the type of saccharide residue and the attachment position of the sulfate group. Although some GAG-specific bacterial sulfatase activities have been described in the literature, we report here for the first time the identity and the biochemical characterization of four GAG-specific sulfatases. Furthermore, contrary to the current paradigm, we discovered that B. thetaiotaomicron possesses an authentic GAG endosulfatase that is active at the polymer level. This type of sulfatase is the first one to be identified in a bacterium. Our study thus demonstrates that bacteria have evolved more sophisticated and diverse GAG sulfatases than anticipated and establishes how B. thetaiotaomicron, and other major human commensal bacteria, can metabolize and potentially tailor complex host glycans. 相似文献
3.
Kruiswijk CP Hermsen T van Heerwaarden J Dixon B Savelkoul HF Stet RJ 《Immunogenetics》2005,56(12):894-908
The 16 African large barb fish species of Lake Tana inhabit different ecological niches, exploit different food webs and have different temporal and spatial spawning patterns within the lake. This unique fish species flock is thought to be the result of adaptive radiation within the past 5 million years. Previous analyses of major histocompatibility class II B exon 2 sequences in four Lake Tana African large barb species revealed that these sequences are indeed under selection. No sharing of class II B alleles was observed among the four Lake Tana African large barb species. In this study we analysed the class II B exon 2 sequences of seven additional Lake Tana African large barb species and African large barbs from the Blue Nile and its tributaries. In addition, the presence and variability of major histocompatibility complex class I UA exon 3 sequences in six Lake Tana and Blue Nile African large barb species was analysed. Phylogenetic lineages are maintained by purifying or neutral selection on non-peptide binding regions. Class II B intron 1 and exon 2 sequences were not shared among the different Lake Tana African large barb species or with the riverine barb species. In contrast, identical class I UA exon 3 sequences were found both in the lacustrine and riverine barb species. Our analyses demonstrate complete partitioning of class II B alleles among Lake Tana African large barb species. In contrast, class I alleles remain for the large part shared among species. These different modes of evolution probably reflect the unlinked nature of major histocompatibility genes in teleost fishes.Electronic Supplementary Material Supplementary material is available for this article at .An erratum to this article can be found at 相似文献
4.
Different cis-Acting Elements Are Involved in the Regulation of TRP1 and TRP2 Promoter Activities by Cyclic AMP: Pivotal Role of M Boxes (GTCATGTGCT) and of Microphthalmia 总被引:7,自引:0,他引:7 下载免费PDF全文
5.
Rosanna Pescini Gobert Monique van den Eijnden Cedric Szyndralewiez Catherine Jorand-Lebrun Dominique Swinnen Linfeng Chen Corine Gillieron Fiona Pixley Pierre Juillard Patrick Gerber Caroline Johnson-L��ger Serge Halazy Montserrat Camps Agnes Bombrun Margaret Shipp Pierre-Alain Vitte Vittoria Ardissone Chiara Ferrandi Dominique Perrin Christian Rommel Rob Hooft van Huijsduijnen 《The Journal of biological chemistry》2009,284(17):11385-11395
6.
7.
Supriti Paul Corine Mathonière Rodolphe Clérac Debashis Ray 《Inorganica chimica acta》2011,370(1):108-116
Reaction of the imidazolidinyl phenolate-based ligand, H3L [(2-(2′-hydroxyphenyl)-1,3-bis[4-(2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine)] with Cu(ClO4)2·6H2O produces an aqua-bridged cationic reactant complex [Cu2(μ-H2O)(μ-L)][ClO4]·1.5H2O (1·1.5H2O). Solution phase interaction of 1·1.5H2O with SCN− anions in 1:1 molar ratio leads to [Cu2(μ-L)(NCS)]·2H2O (2·2H2O) that does not possess anymore the reactive aqua bridge but instead a terminal SCN− anion coordinated only to one CuII ion. Whereas in 1:2 molar ratio, partial extrusion of the CuII ions takes place to generate in situ [Cu(NCS)3(OH2)]− anions. These complex anions then quantitatively replace anions in 1·1.5H2O via ‘anion metathesis’ and concurrently remove the aqua bridge by coordination of linear MeCN to one of the CuII ions to give [Cu2(μ-L)(CH3CN)][Cu(NCS)3(OH2)] (3). The literature unknown [Cu(NCS)3(OH2)]− anion forms an intimate H-bonded assembly with the cationic part of 3 to yield a novel [Cu3] isosceles triangle. The precursor complex is known as antiferromagnetic whereas in 2·2H2O, the CuII (S = 1/2) ions in a dinuclear entity exhibit ferromagnetic interactions (J/kB = +15.0 K and g = 2.22) to yield an ST = 1 spin ground state in good agreement with the M versus H data below 8 K. 相似文献
8.
Corine M. Eising Raquel Robles Maarten Lasthuizen Ton G. G. Groothuis 《Journal of avian biology》2009,40(6):635-639
Substantial amounts of maternal androgens are found in birds’ eggs and have been shown to benefit offspring development. Within‐clutch patterns of increasing androgen concentrations over the laying sequence are often hypothesized to compensate for the negative effects of hatching asynchrony. However, detrimental effects to offspring fitness of exposure to high yolk androgen levels have also been demonstrated. This suggests that mothers should forego these costs to their offspring when the need for compensation for hatching asynchrony is low or when alternative compensatory strategies, e.g. in terms of increasing egg mass, are available. Here we show that in the south‐temperate lesser double‐collared sunbird Nectarinia chalybea, a species with hatching asynchrony but also with high survival of last‐hatched chicks, mothers do not deposit resources differentially in terms of either yolk androgen concentration or egg mass across the laying sequence. We discuss to what extend this challenges the original explanation of within‐clutch variation in these egg parameters and offer some explanation for their between‐clutch variation which was related to female body mass. 相似文献
9.
Casein kinase 1alpha interacts with retinoid X receptor and interferes with agonist-induced apoptosis 总被引:3,自引:0,他引:3
Zhao Y Qin S Atangan LI Molina Y Okawa Y Arpawong HT Ghosn C Xiao JH Vuligonda V Brown G Chandraratna RA 《The Journal of biological chemistry》2004,279(29):30844-30849
Agonists of retinoid X receptors (RXRs), which include the natural 9-cis-retinoic acid and synthetic analogs, are potent inducers of growth arrest and apoptosis in some cancer cells. As such, they are being used in clinical trials for the treatment and prevention of solid tumors and are used to treat cutaneous T cell lymphoma. However, the molecular mechanisms that underlie the anti-cancer effects of RXR agonists remain unclear. Here, we show that a novel pro-apoptotic pathway that is induced by RXR agonist is negatively regulated by casein kinase 1alpha (CK1alpha). CK1alpha associates with RXR in an agonist-dependent manner and phosphorylates RXR. The ability of an RXR agonist to recruit CK1alpha to a complex with RXR in cells correlates inversely with its ability to inhibit growth. Remarkably, depletion of CK1alpha in resistant cells renders them susceptible to RXR agonist-induced growth inhibition and apoptosis. Our study shows that CK1alpha can promote cell survival by interfering with RXR agonist-induced apoptosis. Inhibition of CK1alpha may enhance the anti-cancer effects of RXR agonists. 相似文献
10.
Beuret L Flori E Denoyelle C Bille K Busca R Picardo M Bertolotto C Ballotti R 《The Journal of biological chemistry》2007,282(19):14140-14147