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61.
Jianping Wang Yuriy A. Knirel Ruiting Lan Sof'ya N. Senchenkova Xia Luo Andrei V. Perepelov Yiting Wang Alexander S. Shashkov Jianguo Xu Qiangzheng Sun 《Journal of bacteriology》2014,196(8):1525-1531
O antigen (O polysaccharide) is an important and highly variable cell component present on the surface of cells which defines the serospecificity of Gram-negative bacteria. Most O antigens of Shigella flexneri, a cause of shigellosis, share a backbone composed of →2)-α-l-RhapIII-(1→2)-α-l-RhapII-(1→3)-α-l-RhapI-(1→3)-β-d-GlcpNAc-(1→ repeats, which can be modified by adding various substituents, giving rise to 19 serotypes. The known modifications include glucosylation on various sugar residues, O-acetylation on RhaI, and phosphorylation with phosphoethanolamine on RhaII or/and RhaIII. Recently, two new O-antigen modifications, namely, O-acetylation at position 3 or 4 of RhaIII and position 6 of GlcNAc, have been identified in several S. flexneri serotypes. In this work, the genetic basis for the 3/4-O-acetylation on RhaIII was elucidated. Bioinformatic analysis of the genome of S. flexneri serotype 2a strain Sf301, which carries 3/4-O-acetylation on RhaIII, revealed an O-acyltransferase gene designated oacB. Genetic studies combined with O-antigen structure analysis demonstrated that this gene is responsible for the 3/4-O-acetylation in serotypes 1a, 1b, 2a, 5a, and Y but not serotype 6, which has a different O-antigen backbone structure. The oacB gene is carried by a transposon-like structure located in the proA-adrA region on the chromosome, which represents a novel mechanism of mobilization of O-antigen modification factors in S. flexneri. These findings enhance our knowledge of S. flexneri O-antigen modifications and shed light on the origin of new O-antigen variants. 相似文献
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A S Shashkov A N Kondakova S N Senchenkova K Zych F V Toukach Y A Knirel Z Sidorczyk 《European journal of biochemistry》2000,267(2):601-605
Lipopolysaccharide of Proteus penneri strain 63 was degraded by mild acid to give a high molecular mass O-specific polysaccharide that was isolated by gel-permeation chromatography. Sugar and methylation analyses and NMR spectroscopic studies, including two-dimensional 1H, 1H COSY, TOCSY rotating-frame NOE spectroscopy, H-detected 1H,13C and 1H,31P heteronuclear multiple-quantum coherence (HMQC), and 1H, 13C HMQC-TOCSY experiments, demonstrated the following structure of the polysaccharide: where FucNAc is 2-acetamido-2,6-dideoxygalactose and PEtn is 2-aminoethyl phosphate. The polysaccharide studied shares some structural features, such as the presence of D-GlcNAc6PEtn and an alpha-L-FucNAc-(1-->3)-D-GlcNAc disaccharide, with other Proteus O-specific polysaccharides. A marked cross-reactivity of P. penneri 63 O-antiserum with P. vulgaris O12 was observed and substantiated by a structural similarity of the O-specific polysaccharides of the two strains. In spite of this, the polysaccharide of P. penneri 63 has the unique structure among Proteus O-antigens, and therefore a new, separate serogroup, O68, is proposed for this strain. 相似文献
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Abstract The discovery of the derivatives of 2,3-diamino-2,3-dideoxyuronic acids and 5,7-diamino-3,5,7,9-tetradeoxynonulosonic acids in bacterial polysaccharides enlarges the list of natural monosaccharides. Many of the new sugars carry unusual N -substituents, such as formyl, ( R )-3-hydroxybutyryl, and acetimidoyl groups. They are most characteristics of O-chains of Pseudomonas aeruginosa lipopolysaccharides, composed almost exclusively of amino sugars or amphoteric amino sugars; the latter seem to play an important role as serological determinants. The identification of these sugars and the structural determination of the O-specific polysaccharides provide the chemical basis for the classification of P. aeruginosa strains. Some of the new monosaccharides enter also the polysaccharides from some other bacteria. 相似文献
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目的:分析特定人群超重患病率,以及超重与高血压、糖尿病、血脂异常、脂肪肝等相关疾病的关系,为及早预防慢性非传染性疾病奠定基础。方法:对平房地区采取长效避孕措施的603名户籍农村已婚育龄妇女进行健康体检,按体重指数(BMI)分为正常组、超重组和肥胖组,比较各组间高血压、高血糖、高血脂、脂肪肝等相关疾病检出率的差异。结果:特定人群超重发病率及超重相关疾病检出率的差异均具有统计学意义(P〈0.01)。结论:平房地区特定人群超重及肥胖发病率未明显高于国内平均水平及全市水平。但超重及肥胖与高血压、糖尿病、血脂异常、脂肪肝等疾病存在较大相关关系,为了进一步降低心脑血管高危因素和死亡率。需采取早期、有效的措施控制超重和肥胖倾向。 相似文献
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2021年4月,我国15头野生亚洲象(Elephas maximus)从西双版纳一路北迁至昆明市受到了全世界的关注,分析我国野生亚洲象分布区土地利用变化、生态系统服务供需关系如何影响野生亚洲象分布,对保护亚洲象与提高当地人类福祉具有重要的意义。利用生态系统服务价值当量因子法和生态系统服务需求模型计算中国野生亚洲象分布区1990、2005、2015年生态系统服务供给价值与需求指数,通过空间标准化匹配出四种生态系统服务供需模式,探究我国野生亚洲象偏好分布的供需模式。结果表明,林地、草地和耕地是最主要的土地利用类型,1990—2015年,林地、草地和耕地的面积变化率分别为1.09%、-4.82%、-4.86%。1990、2005、2015年生态系统供给总价值分别为6108.55亿元、7434.41亿元、13973.37亿元;生态系统服务需求不断提高,整体呈现中间高,四周低的分布格局。在研究的25年内,亚洲象分布于高供给-高需求与高供给-低需求区域,且有向高供给-高需求区域迁徙的趋势。 相似文献
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WU YA LAN GUO HUANG FAN JIAN ZHAO YIZHANG TIAN HUA ZHOU LAN MA GANG PEI 《Cell research》1997,7(2):207-215
INTRODUCTIONOpioidreceptorsbelongtotheG-protein-coupledreceptorfamilythatischaracterizedbytheseventransmembranespanningdomainsinstructure.Threesubtypesoftheopioidreceptors(H,6,andK)havebeenclonedandcharacterizedthroughtheir1.CorrespondingauthorFunctionalexpressionofORLIandN/OFQduringmouseembryogenesisdistinctaffinitiesfordifferentopioidligands.TheseopioidreceptorsareallcoupledtotheinhibitoryGprotein(Gi)andnegativelyregulateadenylatecyclase[1].Opioidreceptor--likereceptor(ORLI),anew… 相似文献