Genome sequence of Bacillus cereus and comparative analysis with Bacillus anthracis

Bacillus cereus is an opportunistic pathogen causing food poisoning manifested by diarrhoeal or emetic syndromes. It is closely related to the animal and human pathogen Bacillus anthracis and the insect pathogen Bacillus thuringiensis, the former being used as a biological weapon and the latter as a pesticide. B. anthracis and B. thuringiensis are readily distinguished from B. cereus by the presence of plasmid-borne specific toxins (B. anthracis and B. thuringiensis) and capsule (B. anthracis). But phylogenetic studies based on the analysis of chromosomal genes bring controversial results, and it is unclear whether B. cereus, B. anthracis and B. thuringiensis are varieties of the same species or different species. Here we report the sequencing and analysis of the type strain B. cereus ATCC 14579. The complete genome sequence of B. cereus ATCC 14579 together with the gapped genome of B. anthracis A2012 enables us to perform comparative analysis, and hence to identify the genes that are conserved between B. cereus and B. anthracis, and the genes that are unique for each species. We use the former to clarify the phylogeny of the cereus group, and the latter to determine plasmid-independent species-specific markers.     

New 'phantom' dinoflagellate is the causative agent of major estuarine fish kills.

A worldwide increase in toxic phytoplankton blooms over the past 20 years has coincided with increasing reports of fish diseases and deaths of unknown cause. Among estuaries that have been repeatedly associated with unexplained fish kills on the western Atlantic Coast are the Pamlico and Neuse Estuaries of the southeastern United States. Here we describe a new toxic dinoflagellate with 'phantom-like' behaviour that has been identified as the causative agent of a significant portion of the fish kills in these estuaries, and which may also be active in other geographic regions. The alga requires live finfish or their fresh excreta for excystment and release of a potent toxin. Low cell densities cause neurotoxic signs and fish death, followed by rapid algal encystment and dormancy unless live fish are added. This dinoflagellate was abundant in the water during major fish kills in local estuaries, but only while fish were dying; within several hours of death where carcasses were still present, the flagellated vegetative algal population had encysted and settled back to the sediments. Isolates from each event were highly lethal to finfish and shellfish in laboratory bioassays. Given its broad temperature and salinity tolerance, and its stimulation by phosphate enrichment, this toxic phytoplankter may be a widespread but undetected source of fish mortality in nutrient-enriched estuaries.     

The genome sequence of Bacillus anthracis Ames and comparison to closely related bacteria

Bacillus anthracis is an endospore-forming bacterium that causes inhalational anthrax. Key virulence genes are found on plasmids (extra-chromosomal, circular, double-stranded DNA molecules) pXO1 (ref. 2) and pXO2 (ref. 3). To identify additional genes that might contribute to virulence, we analysed the complete sequence of the chromosome of B. anthracis Ames (about 5.23 megabases). We found several chromosomally encoded proteins that may contribute to pathogenicity--including haemolysins, phospholipases and iron acquisition functions--and identified numerous surface proteins that might be important targets for vaccines and drugs. Almost all these putative chromosomal virulence and surface proteins have homologues in Bacillus cereus, highlighting the similarity of B. anthracis to near-neighbours that are not associated with anthrax. By performing a comparative genome hybridization of 19 B. cereus and Bacillus thuringiensis strains against a B. anthracis DNA microarray, we confirmed the general similarity of chromosomal genes among this group of close relatives. However, we found that the gene sequences of pXO1 and pXO2 were more variable between strains, suggesting plasmid mobility in the group. The complete sequence of B. anthracis is a step towards a better understanding of anthrax pathogenesis.     

一种电容传感器检测定位扬声器接线端子的方法

基于平面电容传感器原理,提出一种应用于扬声器接线端子定位检测系统的新型电容传感器,可以有效检测定位扬声器接线端子。介绍了这种电容传感器的设计,描述了电容传感器用于检测扬声器接线端子的基本方法;并给出了相应的电路模型。根据扬声器接线端子的外形特点来确定电容传感器的最优设计。实验结果表明:电容传感器对扬声器接线端子区域较敏感,电容-频率变换振荡器输出频率为51 k Hz左右的波形,相对频率差约5 k Hz。通过检测振荡器的频率变化,运用自学习均值滤波频率采集算法可实现扬声器接线端子的非接触检测定位。     

EDTA滴定法检测水泥搅拌桩水泥含量影响因素试验研究

为研究EDTA(乙二酸四乙酸二钠)滴定法运用于水泥搅拌桩水泥含量检测的适用性,进行了不同龄期下不同水泥含量的EDTA消耗量试验和不同粒径范围时EDTA消耗量试验。试验研究结果表明:在水泥含量较低时(小于10%),水泥含量与EDTA消耗量近似成线性关系;随着水泥含量的增加,EDTA消耗量增加速率逐渐减少,EDTA消耗量与水泥含量关系曲线呈现非线性特性。不同粒径范围下EDTA消耗量与颗粒的粒径近似成反比关系,随着水泥土的粒径的增大,EDTA滴定平行样之间的离散性增加,过2 mm标准筛的水泥土满足试验离散性和误差要求。通过对水泥搅拌水泥含量分布范围内的水泥含量与EDTA消耗量相关性分析,认为用双曲线拟合效果较好。利用水泥含量的倒数与EDTA消耗量的倒数成线性关系制成的标准曲线可用于现场实际检测。     

一株产NAD+依赖型甘油脱氢酶嗜热杆菌的筛选

将采集于清源山、华大后山果园、华大南浦果园、实验室附近等多处的高温堆肥样品在60℃、pH7.0条件下进行富集培养,其中南浦果园堆肥样品菌体长势较好,菌株呈暗绿色;逐步提高培养基中甘油浓度(0.5g/L~3g/L),进行菌株产甘油脱氢酶(GDH)的驯化培养与复筛,经8个批次的复筛,获得一株产GDH酶活达0.201U/mL的棕色菌株,编号TB8-5;经镜检分析同时结合菌落生长特性并经生理生化实验反应鉴定,初步判断筛选出的菌株属嗜热芽孢杆菌属;菌株发酵液中产物组分鉴定为二羟基丙酮(DHA),含量为0.597mg/mL,相应的GDH酶活也最高,其最适反应温度为50℃,最适反应条件pH为8.0,Zn2 对酶活有一定的促进作用.     

溶菌酶高产链霉菌RX-17的筛选及其特性研究

在添加变链球菌(Strephtococcus mutans)菌体的双层平板上，筛选到一株产溶菌酶能力较高的放线菌RX-17，将其初步归为链霉菌黄色类群，对产酶进程监测表明，该菌产酶与生长密切相关，72h酶活力可达185U／mL．RX-17所产溶菌酶溶菌谱广泛，能够溶解多种卵清溶菌酶不能作用的革兰氏阳性与阴性细菌，对金黄色葡萄球菌(Staphylococcus aureus)及变链球菌族细菌溶解能力较强．通过CM-Sephadex C-50离子交换层析，对RX-17溶菌酶粗制品进行了初步分离，得到了3个有溶菌活力的组分.     

苗族正骨方药"恶罗汉"的药理药效及其制备

骨折、骨关节脱位、软组织损伤，敷用苗药“恶罗汉”，凉爽舒适，疼痛速减，消除滞积，供血畅通，伤口愈合，创伤修复．对皮肤无过敏，愈后不会因损伤导致肌肉萎缩，不会因气候变化发生疼痛，治愈周期短。     

Agent及测试床框架描述

指出Agent的行为特点是对环境的交化做出反应，Agent与环境的相互作用能用一个框架程序来描述；环境可以分为几类，Agent测试环境，即测试床，也可以用一个框架程序来描述；在此基础上给出一般性的Agent和测试床框架的描述．     

ZnO nanofluids - A potential antibacterial agent

In this work, ZnO nanofluids were produced by a medium mill with a pH value of about 7.2 and characterized by Nano-Sizer and SEM. After milling, ZnO nanofluids were formed with an average particle size of～198.4 nm. The ZnO nanofluids used for testing were stored for different periods (1-, 90- and 120-day) and kept in different conditions (under the light and in the dark). The antibacterial activ- ities of these ZnO nanofluids were evaluated by estimating the reduction ratio of the bacteria treated with ZnO. The results showed that the ZnO nanofluid stored for 120 days under the light had the best antibacterial behavior against Escherichia coli DH5α. SEM images suggest that an interaction between the ZnO particles and the E. Coli bacteria cells caused by electrostatic forces might be a mechanism.     

A novel selective broad-spectrum anti-DNA virus agent

A new compound has been found, (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine ((S)-HPMPA), that has potent and selective activity against a broad spectrum of DNA viruses, including herpes simplex virus (types 1 and 2); varicella zoster virus; thymidine kinase-deficient (TK-) mutants of herpes simplex and varicella zoster virus; human cytomegalovirus; phocid, simian, suid, bovid and equid herpesviruses; African swine fever virus; vaccinia virus; and human adenoviruses. It is also active against retroviruses. We also report that, in mice and rabbits in vivo, the compound is effective against both local and systemic infections with herpes simplex virus type 1, including herpetic keratitis caused by a TK- mutant which is resistant to the classical anti-herpes drugs.     

简论人类造貌营力

在人类活动已成为一种造貌营力的现代,地貌环境（特别是城市地貌环境）的演变和发展已成为一种“自然－人文”过程。探讨了人类造貌营力的性质、及其自然地貌的作用方式和强度。在此基础上,分析了影响人类造貌营力的人文因素,并简要地介绍了对人类造貌营力研究和评价的构想。     

一种基于JXTA的Mobile Agent平台系统

对比分析了JXTA技术和Mobile Agent的技术特点,提出了一种基于JXTA技术的Mobile Agent平台系统.该系统提供了一种基于JXTA的查找、通信、安全解决方案,以提高移动代理的健壮性、安全性和代理间的交互性;对该系统中关键技术的实现机制进行了分析说明.最后在实验原型系统的基础上对系统的性能进行了分析.