文昌鱼RACK1基因在胚胎发育中的表达

脊椎动物活化的(蛋白)激酶C受体1(receptor for activated C-kinase 1,RACK1)在胚胎发育过程中起着至关重要的作用.克隆了RACK1基因在青岛文昌鱼(Branchiostoma belcheri)中的同源基因AmphiRACK1,对其进行了系统的进化学分析,并研究了该基因在正常胚胎发育过程中和经LiCl处理胚胎发育中的时空表达图式.系统进化学分析结果表明,文昌鱼RACK1位于脊椎动物进化枝的基部.在正常胚胎发育中,AmphiRACK1基因在脑泡、神经管和体节中都有明显的表达.在经LiCl处理的胚胎中,该基因在体节中的分节型表达变模糊,表达下调;在脑泡和神经管中的表达下调甚至消失.此外,在成体文昌鱼的轮器、鳃血管、肝盲囊和肠上皮以及精巢中都检测到AmphiRACK1基因不同程度的表达.

An analytical model for guided wave inspection optimization for prismatic structures of any cross section.

This paper presents an analytical modeling technique for the simulation of long-range ultrasonic guided waves in structures. The model may be used to predict the displacement field in a prismatic structure arising from any excitation arrangement and may therefore be used as a tool to design new inspection systems. It is computationally efficient and relatively simple to implement, yet gives accuracy similar to finite element analysis and semi-analytical finite element analysis methods. The model has many potential applications; one example is the optimization of part-circumferential arrays where access to the full circumference of the pipe is restricted. The model has been successfully validated by comparison with finite element solutions. Experimental validation has also been carried out using an array of piezoelectric transducer elements to measure the displacement field arising from a single transducer element in an 88.9-mm-diameter pipe. Good agreement has been obtained between the two models and the experimental data.

长江江豚感染铜绿假单胞菌肺炎的诊治

本文记录了一例患急性铜绿假单胞菌肺炎的长江江豚诊断、治疗和预后观察过程。病原学鉴定采用鲜血琼脂平板对该江豚鼻腔拭子,在37℃下进行细菌需氧、厌氧培养和分离,并对所分离的细菌种类进行细菌学鉴定,结合血常规和血生化的检测结果,判定病原为铜绿假单胞菌(Pseudomonasaeruginosa,PA)。依据病原菌的药敏试验结果对患病江豚进行治疗,预后良好。通过对整个过程的资料分析以及预后观察,得到如下提示:1)应做好饲养环境的消毒措施,防止江豚出现获得性PA感染;2)对江豚日常呼吸道和粪便中PA的检测,有利于疾

Predictive coding and the slowness principle: an information-theoretic approach.

Understanding the guiding principles of sensory coding strategies is a main goal in computational neuroscience. Among others, the principles of predictive coding and slowness appear to capture aspects of sensory processing. Predictive coding postulates that sensory systems are adapted to the structure of their input signals such that information about future inputs is encoded. Slow feature analysis (SFA) is a method for extracting slowly varying components from quickly varying input signals, thereby learning temporally invariant features. Here, we use the information bottleneck method to state an information-theoretic objective function for temporally local predictive coding. We then show that the linear case of SFA can be interpreted as a variant of predictive coding that maximizes the mutual information between the current output of the system and the input signal in the next time step. This demonstrates that the slowness principle and predictive coding are intimately related.

Guidance of collective cell migration by substrate geometry.

Collective behavior refers to the emergence of complex migration patterns over scales larger than those of the individual elements constituting a system. It plays a pivotal role in biological systems in regulating various processes such as gastrulation, morphogenesis and tissue organization. Here, by combining experimental approaches and numerical modeling, we explore the role of cell density ('crowding'), strength of intercellular adhesion ('cohesion') and boundary conditions imposed by extracellular matrix (ECM) proteins ('constraints') in regulating the emergence of collective behavior within epithelial cell sheets. Our results show that the geometrical confinement of cells into well-defined circles induces a persistent, coordinated and synchronized rotation of cells that depends on cell density. The speed of such rotating large-scale movements slows down as the density increases. Furthermore, such collective rotation behavior depends on the size of the micropatterned circles: we observe a rotating motion of the overall cell population in the same direction for sizes of up to 200 μm. The rotating cells move as a solid body, with a uniform angular velocity. Interestingly, this upper limit leads to length scales that are similar to the natural correlation length observed for unconfined epithelial cell sheets. This behavior is strongly altered in cells that present a downregulation of adherens junctions and in cancerous cell types. We anticipate that our system provides a simple and easy approach to investigate collective cell behavior in a well-controlled and systematic manner.

In situ studies on the bioaccumulation of microcystins in the phytoplanktivorous silver carp (Hypophthalmichthys molitrix) stocked in Lake Taihu with dense toxic Microcystis blooms

The phytoplanktivorous silver carp is an important biomanipulation fish to control cyanobacterial blooms and is also a food fish with the greatest production in China. The accumulation of the hepatotoxic microcystins (MCs) determined by LC-MS in various organs of silver carp was studied monthly in Lake Taihu dominated by toxic Microcystis aeruginosa. Average recoveries of spiked fish samples were 78% for MC-RR and 81% for MC-LR. The highest content of MCs was found in the intestine (97.48 mu g g(-1) DW), followed by liver (6.84 mu g g(-1) DW), kidney (4.8 8 mu g g(-1) DW) and blood (1.54 mu g g(-1) DW), and the annual mean MC content was in the order of intestine > liver > kidney > blood > muscle > spleen > gallbladder > gill. Silver carp could effectively ingest toxic Microcystis cells (up to 84.4% of total phytoplankton in gut contents), but showed fast growth (from 141 g to 1759 g in I year in mean weight). Silver carp accumulated less microcystins in liver than other animals in the same site or other fish from different water bodies at similar level of toxin ingestion. There was possible inhibition of the transportation of the most toxic MC-LR across the gutwall. Muscle of silver carp in Lake Taihu should not be consumed during period of dense Microcystis blooms while viscera were risky for consumption in more months. (c) 2006 Elsevier B.V. All rights reserved.

Sagnac棱镜角公差与干涉光谱仪光谱分辨率的关系分析

根据干涉成像光谱仪光谱分辨率对角向差的要求，通过对实体Sagnac干涉仪结构和光路 进行分析，从三个相互垂直的方向出发，研究了光谱分辨率和棱镜角公差之间存在的关系；并推导 了满足光谱仪光谱分辨率要求的实体Sagnac干涉棱镜的角公差公式；用实例说明了关系式的应用 方法，如果不考虑棱镜变形引起的色散及棱镜的面型误差和付氏镜的残余像差的影响，而只考虑棱 镜的角误差对光谱分辨率的影响，则通常情况下干涉棱镜的角公差要求较严，约2O”以内．

Quasi-Thermodynamic Model for MOVPE of AlGaN

国家863计划,国家自然科学基金