Complete genomic characterization of a pathogenic A.II strain of Francisella tularensis subspecies tularensis

Francisella tularensis is the causative agent of tularemia, which is a highly lethal disease from nature and potentially from a biological weapon. This species contains four recognized subspecies including the North American endemic F. tularensis subsp. tularensis (type A), whose genetic diversity is correlated with its geographic distribution including a major population subdivision referred to as A.I and A.II. The biological significance of the A.I - A.II genetic differentiation is unknown, though there are suggestive ecological and epidemiological correlations. In order to understand the differentiation at the genomic level, we have determined the complete sequence of an A.II strain (WY96-3418) and compared it to the genome of Schu S4 from the A.I population. We find that this A.II genome is 1,898,476 bp in size with 1,820 genes, 1,303 of which code for proteins. While extensive genomic variation exists between "WY96" and Schu S4, there is only one whole gene difference. This one gene difference is a hypothetical protein of unknown function. In contrast, there are numerous SNPs (3,367), small indels (1,015), IS element differences (7) and large chromosomal rearrangements (31), including both inversions and translocations. The rearrangement borders are frequently associated with IS elements, which would facilitate intragenomic recombination events. The pathogenicity island duplicated regions (DR1 and DR2) are essentially identical in WY96 but vary relative to Schu S4 at 60 nucleotide positions. Other potential virulence-associated genes (231) varied at 559 nucleotide positions, including 357 non-synonymous changes. Molecular clock estimates for the divergence time between A.I and A.II genomes for different chromosomal regions ranged from 866 to 2131 years before present. This paper is the first complete genomic characterization of a member of the A.II clade of Francisella tularensis subsp. tularensis.     

Conservation, variability and the modeling of active protein kinases

The human proteome is rich with protein kinases, and this richness has made the kinase of crucial importance in initiating and maintaining cell behavior. Elucidating cell signaling networks and manipulating their components to understand and alter behavior require well designed inhibitors. These inhibitors are needed in culture to cause and study network perturbations, and the same compounds can be used as drugs to treat disease. Understanding the structural biology of protein kinases in detail, including their commonalities, differences and modes of substrate interaction, is necessary for designing high quality inhibitors that will be of true use for cell biology and disease therapy. To this end, we here report on a structural analysis of all available active-conformation protein kinases, discussing residue conservation, the novel features of such conservation, unique properties of atypical kinases and variability in the context of substrate binding. We also demonstrate how this information can be used for structure prediction. Our findings will be of use not only in understanding protein kinase function and evolution, but they highlight the flaws inherent in kinase drug design as commonly practiced and dictate an appropriate strategy for the sophisticated design of specific inhibitors for use in the laboratory and disease therapy.     

Relationship between thermodynamic driving force and one-way fluxes in reversible processes

Chemical reaction systems operating in nonequilibrium open-system states arise in a great number of contexts, including the study of living organisms, in which chemical reactions, in general, are far from equilibrium. Here we introduce a theorem that relates forward and reverse fluxes and free energy for any chemical process operating in a steady state. This relationship, which is a generalization of equilibrium conditions to the case of a chemical process occurring in a nonequilibrium steady state in dilute solution, provides a novel equivalent definition for chemical reaction free energy. In addition, it is shown that previously unrelated theories introduced by Ussing and Hodgkin and Huxley for transport of ions across membranes, Hill for catalytic cycle fluxes, and Crooks for entropy production in microscopically reversible systems, are united in a common framework based on this relationship.     

正常人耵聍中马拉色菌菌种构成研究

目的研究正常人耵聍中马拉色菌菌种构成及同一宿主耵聍中菌种是否一致。方法采集45名健康志愿者双侧耵聍,0.1%曲拉通X-100溶解稀释后接种于含菜籽油培养基,生化及形态学方法鉴定到种,同时提取菌种DNA,用真菌通用引物ITS1/ITS4做PCR扩增并测序鉴定。结果有44例(97.78%)双侧耵聍中均培养出马拉色菌(共分离出88株菌),菌种构成:糠粃马拉色菌29株(32.95%)、斯洛菲马拉色菌23株(26.14%)、合轴马拉色菌18株(20.45%)、球形马拉色菌11株(12.50%)、限制性马拉色菌7株(7.95%)。44例(88株菌)中双侧耵聍菌种相同者有38例(76株菌)(一致率86.36%)。结论正常人耵聍中马拉色菌菌种分布较广,主要菌种为糠秕马拉色菌。同一宿主双侧耵聍中马拉色菌菌种具有一定的一致性。     

紫外辐射对东北红豆杉鲜叶中紫杉醇及三尖杉宁碱含量的影响

分别采用254、365 nm两种波长的紫外光对东北红豆杉鲜叶进行辐射,研究了波长、辐射时间以及样品处理方式对东北红豆杉鲜叶中紫杉醇及三尖杉宁碱含量变化的影响。结果表明,东北红豆杉鲜叶经匀浆处理后接受紫外辐射,两种波长的紫外光都可以使紫杉醇及三尖杉宁碱的含量增加,但不同波长对紫杉醇及三尖杉宁碱含量提高的趋势却不相同。365 nm的紫外光辐射2 h时使紫杉醇和三尖杉宁碱含量均提高到了最大值,两种物质含量分别提高了44.6%和53.0%,而254 nm的紫外光在辐射8 h时才达到最大值,两种物质含量分别提高了39.2%和24.3%。可以选取365 nm的紫外光对东北红豆杉鲜叶水匀浆体系进行辐射,快速高效地提高鲜叶内紫杉醇和三尖杉宁碱的含量。     

黑龙江省南部农村白内障术后视力的调查

目的:调查白内障的手术情况并评估其手术疗效。方法:采用整群随机抽样方法将黑龙江省南部农村人口按一定的标准划分成抽样单位,两组人员通过预实验统一标准后对年龄(?)50岁共5058人(受检率91%)进行视力和眼部检查,先后在其中的两个抽样单位进行一致性检验。结果:高年龄组、女性和低教育程度者的白内障患病率较高。在所有调查的68只白内障手术眼,最佳矫正视力(?)20/60的占51.5%(35/68)。结论:白内障是50及50岁以上农村人口的主要致盲眼病,迫切需要提高手术质量是关键,特别是高龄和女性患者。     

肾上腺素对THP-1巨噬细胞TGF-β1、SR-A1和CD36表达的影响

目的:探讨肾上腺素对THP-1巨噬细胞TGF-β1、SR-A1和CD36表达的影响。方法:不同浓度肾上腺素处理THP-1巨噬细胞24h,运用逆转录多聚酶链反应检测其TGF-β1、SR-A1和CD36的mRNA表达,酶联免疫吸附试验检测TGF-β1蛋白的表达,Westem-blotting检测SR-A1蛋白的表达。结果:100nmol/L及1μmol/L的肾上腺素作用THP-1巨噬细胞,引起TGF-β1 mR- NA和蛋白表达下调(p<0.05),SR-A1 mRNA和蛋白表达上调(P<0.05),1pmol/L～1μmol/L的肾上腺素处理后,各组CD36 mRNA水平无显著性变化(p>0.05)。结论:应激浓度的肾上腺素可能通过影响TGF-β1和SR-A1的表达而参与和/或促进AS的发生发展。     

法尼酯X受体对肝脂酶表达的影响

目的:探讨法尼酯X受体(farnesoid X receptor,FXR)对肝脂酶(hepatic lipase,HL)表达的影响。方法:用FXR激动剂CDCA作用人肝癌细胞株(HepG2),用RT-PCR和Western blotting检测HL的表达情况。结果:用不同浓度的CDCA(25μmol/L、50μmol/L、75μmol/L)分别作用HepG2细胞6h、12h、24h、48h后,HL的mRNA和蛋白质水平呈时间和剂量依赖性下调。结论:FXR激动剂可抑制肝脂酶的表达。     

胆囊切除术医源性胆管损伤的处理

目的:探讨开腹胆囊切除术医源性胆道损伤的诊断、手术时机和手术方式的选择。方法:对18例胆道损伤进行分析总结:分别施行了胆管修补、T管引流术10例,保守治疗2例,Roux-en-Y胆肠吻合术6例。结果:3例术后过早拔管发生吻合口狭窄,再次手术。1例因梗阻性胆管炎并发肝功能衰竭、多器官功能衰竭死亡。1例因胆肠吻合术后并发消化道出血、肝昏迷死亡。余术后良好。结论:尽早发现及正确处理对提高疗效和预防术后胆管狭窄起着决定性的作用。术中发现胆管损伤立即行端端吻合加T管引流;术后数天发现或多次胆道修补术失败者,则宜行规范的Roux-en-Y胆肠吻合术。     

东北林蛙皮肤中一类新抗菌肽cDNA的克隆及成熟肽的预测

为进一步研究和开发高效广谱天然抗生素的抗菌肽,本文克隆东北林蛙(Rana dybowskii)的抗菌肽基因,并预测其成熟肽的有关性质。根据蛙属抗菌肽信号肽末端序列设计简并引物,以RT-PCR技术扩增皮肤中抗菌肽的cDNA,并进行克隆测序。用生物信息学软件分析cDNA序列特点,预测成熟肽的理化性质。研究发现一种长度为28个氨基酸残基的新抗菌肽dybowsin-1,该肽具有Rana box结构;与已发现的抗菌肽仅有35%的同源性;理论等电点在9.70-10.01之间;均呈阳离子性;从第3或4个氨基酸开始到第16个氨基酸形成α-螺旋结构,极性氨基酸位于螺旋轮的一侧,非极性氨基酸位于螺旋轮的另一侧;具有N-端疏水、C-端亲水的两亲性。一个个体表达5条cDNA序列编码3种不同的dybowsin-1分子,显示出该抗菌肽表达的多样性。序列分析显示,该抗菌肽可能由多基因座位编码。