Molecular phylogenetics and the origins of placental mammals

The precise hierarchy of ancient divergence events that led to the present assemblage of modern placental mammals has been an area of controversy among morphologists, palaeontologists and molecular evolutionists. Here we address the potential weaknesses o

RESERPINE IMPAIRS SPATIAL WORKING-MEMORY PERFORMANCE IN MONKEYS - REVERSAL BY THE ALPHA-2-ADRENERGIC AGONIST CLONIDINE

Repeated daily treatment with the catecholamine-depleting agent, reserpine, dramatically reduced performance on the delayed response task, a test of spatial working memory that depends upon the integrity of the prefrontal cortex. Delayed response performance fell from an average of 27.2/30 trials correct before reserpine treatment to an average of 20.4/30 trials correct after repeated reserpine administration. Injection of the alpha2-adrenergic agonist, clonidine (0.0001-0.05 mg/kg), to chronic reserpine-treated monkeys significantly restored performance on the delayed response task; performance after an optimal dose averaged 27.8/30 trials correct. Clonidine's beneficial effects on delayed response performance were longlasting; monkeys remained improved for more than 24 h after a single clonidine injection. The finding that clonidine is efficacious in reserpinized animals supports the hypothesis that alpha2-adrenergic agonists improve cognitive function through actions at postsynaptic, alpha2-adrenergic receptors on non-adrenergic cells. In contrast to the delayed response task, reserpine had little effect on performance of a visual discrimination task, a reference memory task which does not depend on the prefrontal cortex. These results emphasize the importance of postsynaptic alpha2-adrenergic mechanisms in the regulation of working memory,

二噁英、多溴联苯醚和多氯联苯同时测定方法的研究

本实验以美国环保署1613B1、614和1668A等标准方法为基础,建立了同一样品中二噁英、多溴联苯醚和多氯联苯的同位素稀释-多层色谱柱净化-高分辨气质联用-高通量同时分析方法。该方法利用弗罗里土对二噁英组分吸附能力强的特点,采用不同极性的溶剂淋洗,先实现二噁英组分和其它两个组分的分离,再利用多溴联苯醚更易保留在硝酸银硅胶(10%)柱上的特点,实现了多溴联苯醚和多氯联苯两类化合物的分离。实验优化了样品前处理过程,纯化过程中去除了大量干扰物质,同时将三类化合物在前处理中进行分离,消除了相互干扰,实现了准确定

黄颡鱼河鲈源吸虫和黄颡前驼形线虫的季节动态和频率分布

2001年2月到2002年7月,对湖北省梁子湖黄颡鱼的胃部寄生蠕虫进行了调查,共发现4种寄生蠕虫,即:黄颡前驼形线虫(Procamallanus fulvidraconis)、杜父鱼驼形线虫(Camallanus cotti)、黄颡刺盖线虫(Spinitectus gigi)和河鲈源吸虫(Genarchopsis goppo),本文主要报道了黄颡前驼形线虫的频率分布,以及河鲈源吸虫的季节动态和频率分布。黄颡前驼形线虫的感染率为96.70%,平均丰度为21.59±23.37,方均比为25.29,与负二项分布

异育银鲫口服不同剂量淀粉后血糖和血脂代谢变化

淡水生态与生物技术国家重点实验室开放课题基金资助

长江中游典型鱼塘植莲的环境与经济效益分析

长江中游湿地区域的池塘经过连续多年的化肥养鱼导致了大量的氮、磷沉积在鱼塘底泥中。分析了鱼塘植莲对养殖后沉积的氮、磷的重新利用及植莲的经济效益。实验于2004年在位于长江中游的武汉市涨渡湖渔场进行。根据收支平衡计算了实验池氮、磷的转移量,根据投入产出计算了实验池的经济收入。逐月分析了池塘中水质理化指标和底泥中总凯氏氮(TKN)和总磷(TP)的含量。方差分析表明:总凯氏氮、总磷在池塘底泥表层(0～5 cm)、中层(5～10 cm)和底层(10～50 cm)当中的含量都出现显著性降低(P<0.05)。养鱼池塘通

鲫鱼肌肉AChE的提取、纯化及活性研究

以鲫鱼肌肉为原料提取乙酰胆碱酯酶(Acetylcholinesterase,AChE),然后采用改进的Ellman方法按照正交试验设计分别测定不同环境条件(pH值,温度,时间)下粗酶液活性,得到测定AChE活性的最佳条件组合。再将粗酶液依次通过DEAE-Sephadex A-50和Sephadex G-200柱层析纯化。结果表明,3个因素对AChE活性影响的顺序为温度>pH值>时间;最佳酶活性测定条件组合为环境温度35℃,体系pH值8.0,反应时间30 min;经Sephadex A-50柱层析后的纯化倍

噬菌体展示随机十肽库的构建及抗WSSV单链抗体A1的模拟抗原表位的淘选和鉴定

本实验以pCANTAB5E噬菌粒为载体,成功构建了较高容量的噬菌体展示随机十肽库,并将其应用于抗原模拟表位的淘选和鉴定。将一种特异识别对虾白斑综合症病毒(Whitespotsyndromevirus,WSSV)的单链抗体A1对十肽库和十五肽库分别进行淘选,结果得到一系列能与单链抗体A1特异性结合的阳性克隆。将这些阳性克隆所编码的多肽氨基酸序列与已知的单链抗体A1的抗原WSSV388片段氨基酸序列做比对,发现多数阳性多肽序列都与WSSV388片段序列的C端一处K????R??R?QS的氨基酸片段相似,由此推

鱼类物种特征尺寸控制因素研究进展

国家973项目(2004CB117402); 中国博士后科学基金(2005037684)

环境胁迫因子对鱼类免疫功能的影响

环境胁迫因子对鱼类免疫功能的影响李彦江育林（中国科学院水生生物研究所，武汉４３００７２）与人类和其他脊椎动物一样，鱼类也是通过其免疫系统识别和消除异物，行使防御、自身稳定和免疫监督三大功能的。鱼病的发生是鱼体、病原和环境三者相互作用的结果。由于鱼类是...

Morphological characteristics and phylogenetic relationship of Anabaena species from Lakes Dianchi and Erhai, China

Although Anabaena is one of the most prevalent planktonic freshwater genus in China, there are few taxonomic reports of Anabaena strains by morphology and genetics. In this study, morphological characteristics and phylogenetic relationships of seven Anabaena strains isolated from two plateau lakes, Lakes Dianchi and Erhai, were investigated. Morphological characteristics such as morphology of filament, cellular shapes and sizes, relative position of heterocytes and akinetes, and presence or absence of aerotopes, were described for these seven strains. Phylogenetic relationships were determined by constructing 16S rRNA gene tree using the neighbor-joining algorithm. The seven strains were morphologically identified as three groups, and phylogenetic analysis based on 16S rRNA gene sequences also showed that these seven strains were in three groups. Strains EH-2, EH-3, and EH-4 were in group A belonging to the Anabaena circinalis and A. crassa group, and strains DC-1, DC-2, and EH-1 were in group B and identified as A. flos-aquae. Strain DC-3 without aerotopes was significantly different from the other isolated strains and was determined as A. cylindrica.

Optical transitions in cubic GaN grown by metalorganic chemical vapor deposition on GaAs (100) substrate

Photoluminescence measurements have been performed on cubic GaN films with carrier concentration as low as 3 x 10(13) cm(-3). From the temperature and excitation intensity dependence, the emission lines at 3.268, 3.150 and 3.081 eV were assigned to the excitonic, donor-acceptor pair, and free-to-acceptor transitions, respectively Additionally, we observed two additional emission lines at 2.926 and 2.821 eV, and suggested that they belong to donor-acceptor pair transitions. Furthermore, from the temperature dependence of integral intensities, we confirmed that three donor-acceptor pair transitions (3.150, 2.926, and 2.821 eV) are from a common shallow donor to three different accepters. The excitonic emission at 3.216 eV has a full-width-at-half-maximum value of 41 meV at room temperature, which indicates a good optical quality of our sample.

基于进化分布式本体的语义Web服务动态发现

在语义Web服务中, 确认分布式本体变动、维护其一致性并实现基于进化的分布式本体的Web服务语义查询成为了一个重要挑战.该文使用SHOQ(D)的分布式描述逻辑扩展 (DDL) 描述相互关联的异构分布式本体,提出了优先分布式知识库(PDK)的概念,探讨了PDK方法的一些重要属性.PDK用来描述分布式本体的进化和更新, 它适用于语义Web服务环境.基于PDK, 文中还给出了相应的语义查询方法,Web服务的语义查询可以归结为检测同这个查询对应的概念在最优先PDK中的p -可满足性.

MPI程序同步通信基本模型死锁检测

本文提出了MPI程序的同步通信模型及三个基本简化模型,给出了判定这些基本模型是否死锁的方法和定理并予以了严格证明.简化模型的死锁检测理论和方法是真实MPI程序死锁检测的必要基础.这些方法基于程序静态分析,必要时进行运行时检测,它们对两种简化模型可以在程序编译前确定是否死锁,对另外一种模型,在编译前可静态确定部分死锁,运行中可确定其他死锁.我们的理论可以证明MPI程序死锁检测主流算法的正确性,其方法可以减少它们对客户源代码或MPI profiling接口的修改量,从而大大降低死锁检测开销,并可在运行前判定死锁.