Aeromonas caviae: ecologic adaptation in the intestinal tract of infants coupled to adherence and enterotoxin production as factors in enteropathogenicity

Aeromonas caviae isolated from stools of diarrheic formula-fed infants and environmental sources produce acetic acid when grown in glucose broth, which is bactericidal (suicide phenomenon). A. caviae grows anaerobically in a minimal medium or under permissive conditions such as the intestinal tract of formula-fed infants. These isolates adhered to HEp-2 cells and produced a cytotoxic and a cytotonic enterotoxin which underscore their enteropathogenicity.     

大型喷浆机器人的灵巧度分析

灵巧度是衡量机器人运动失真程度的重要参数。对机器人灵巧度评价指标进行了对比研究 ,结合大型喷浆机器人自由度较多的特点 ,用雅可比矩阵的条件数对喷浆机器人的灵巧度进行了分析。结果表明 ,大型喷浆机器人在不同形位下的条件数都很小 ,具有较好的运动灵巧度。     

在UBBE框架下考虑不肯定的上界的估计方法

对目前的ＵＢＢＥ模型进行了适当的推广，使在解决估计问题时可以考虑那些可能是误差上界的数值，并在此基础上提出了一种方法，能够通过对估计精度和可靠性进行合理的权衡确定所需估计值，实际案例研究结果表明所提方法能够较好地解决估计精度和可靠性之间的矛盾。     

从著作权角度剖析逢甲大学校园数位内容经营服务管理计画

在数位化与网路化的学术典藏传播大趋势下 ,建构一个完整、方便、迅速与合理使用的校园数位内容经营服务体系 ,是兼具教育与研究两大使命的大学机构必须进行的工作 ,特别是对身负知识典藏与传播责任的图书馆来说 ,更是刻不容缓的任务 .本文介绍逢甲大学图书馆所规划推动的校园数位内容经营服务管理计画 ,探讨其征集服务范围以及提交、互评、加值典藏、传播与版权管理等作业流程 ,并说明所需要的支援团队和人力配置、所产出的产品形式和应用方式 .最后从著作权的角度分析校园数位内容经营服务所涉及的合理使用、著作财产权和著作授权使用问题     

Structure of the detoxification catalyst mercuric ion reductase from Bacillus sp. strain RC607

Several hundred million tons of toxic mercurials are dispersed in the biosphere. Microbes can detoxify organo-mercurials and mercury salts through sequential action of two enzymes, organomercury lyase and mercuric ion reductase (MerA). The latter, a homodimer with homology to the FAD-dependent disulphide oxidoreductases, catalyses the reaction NADPH + Hg(II)----NADP+ + H+ + Hg(0), one of the very rare enzymic reactions with metal substrates. Human glutathione reductase serves as a reference molecule for FAD-dependent disulphide reductases and between its primary structure and that of MerA from Tn501 (Pseudomonas), Tn21 (Shigella), p1258 (Staphylococcus) and Bacillus, 25-30% of the residues have been conserved. All MerAs have a C-terminal extension about 15 residues long but have very varied N termini. Although the enzyme from Streptomyces lividans has no addition, from Pseudomonas aeruginosa Tn501 and Bacillus sp. strain RC607 it has one and two copies respectively of a domain of 80-85 residues, highly homologous to MerP, the periplasmic component of proteins encoded by the mer operon. These domains can be proteolytically cleaved off without changing the catalytic efficiency. We report here the crystal structure of MerA from the Gram-positive bacterium Bacillus sp. strain RC607. Analysis of its complexes with nicotinamide dinucleotide substrates and the inhibitor Cd(II) reveals how limited structural changes enable an enzyme to accept as substrate what used to be a dangerous inhibitor. Knowledge of the mode of mercury ligation is a prerequisite for understanding this unique detoxification mechanism.     

Der Einfluß der Temperatur auf die Giftwirkung des DDT bei Honigbienen (Apis mellifica L.)

Summary The action of DDT on honey-bees depends to a high extent on the temperature (see graph). At 36°C (breeding temperature) DDT has a far weaker insecticidal action than at 20°C (laboratory temperature). This shows that the insecticidal properties of DDT diminish with the raise of temperature.This resistance to DDT at higher temperature is most propitious for bee-keeping and also explains the fact why in agricultural practice there has been no corroborated case of poisoning of bees, though in laboratory tests DDT avered itself to be toxic to bees.