Signaling in the Chemosensory Systems

The mammalian olfactory system is not uniformly organized but consists of several subsystems each of which probably serves distinct functions. Not only are the two major nasal chemosensory systems, the vomeronasal organ and the main olfactory epithelium, structurally and functionally separate entities, but the latter is further subcompartimentalized into overlapping expression zones and projection-related subzones. Moreover, the populations of ‘OR37’ neurons not only express a unique type of olfactory receptors but also are segregated in a cluster-like manner and generally project to only one receptor-specific glomerulus. The septal organ is an island of sensory epithelium on the nasal septum positioned at the nasoplatine duct; it is considered as a ‘mini-nose’ with dual function. A specific chemosensory function of the most recently discovered subsystem, the so-called Grueneberg ganglion, is based on the expression of olfactory marker protein and the axonal projections to defined glomeruli within the olfactory bulb. This complexity of distinct olfactory subsystems may be one of the features determining the enormous chemosensory capacity of the sense of smell.     

On the self-association potential of transmembrane tight junction proteins

Tight junctions seal intercellular clefts via membrane-related strands, hence, maintaining important organ functions. We investigated the self-association of strand-forming transmembrane tight junction proteins. The regulatory tight junction protein occludin was differently tagged and cotransfected in eucaryotic cells. These occludins colocalized within the plasma membrane of the same cell, coprecipitated and exhibited fluorescence resonance energy transfer. Differently tagged strand-forming claudin-5 also colocalized in the plasma membrane of the same cell and showed fluorescence resonance energy transfer. This demonstrates self-association in intact cells both of occludin and claudin-5 in one plasma membrane. In search of dimerizing regions of occludin, dimerization of its cytosolic C-terminal coiledcoil domain was identified. In claudin-5, the second extracellular loop was detected as a dimer. Since the transmembrane junctional adhesion molecule also is known to dimerize, the assumption that homodimerization of transmembrane tight junction proteins may serve as a common structural feature in tight junction assembly is supported. Received 6 October 2005; received after revision 14 December 2005; accepted 27 December 2005 †These authors contributed equally to this work.     

Huntington’s disease: from huntingtin function and dysfunction to therapeutic strategies

Huntington’s disease (HD) is a neurodegenerative disorder that usually starts in middle age and is characterized by involuntary movements (chorea), personality changes and dementia, leading to death within 10–20 years. The defective gene in HD contains a trinucleotide CAG repeat expansion within its coding region that expresses a polyglutamine repeat in the protein huntingtin. Together with the characteristic formation of aggregates in HD, aberrant protein interactions and several post-translational modifications affect huntingtin during disease progression and lead to the dysfunction and death of selective neurons in the brains of patients. The exact molecular mechanisms by which mutant huntingtin induces cell death are not completely understood but may involve the gain of new toxic functions and the loss of the beneficial properties of huntingtin. This review focuses on the cellular functions in which huntingtin is involved and how a better understanding of pathogenic pathways can lead to new therapeutic approaches. Received 24 May 2006; received after revision 5 July 2006; accepted 23 August 2006     

The ubiquitin-specific protease USP25 interacts with three sarcomeric proteins

The biological functions of the more than one hundred genes coding for deubiquitinating enzymes in the human genome remain mostly unknown. The USP25 gene, located at 21q11.2, encodes three protein isoforms produced by alternative splicing. While two of the isoforms are expressed nearly ubiquituously, the expression of the longer USP25 isoform (USP25m) is restricted to muscular tissues and is upregulated during myogenesis. USP25m interacts with three sarcomeric proteins: actin alpha-1 (ACTA1), filamin C (FLNC), and myosin binding protein C1 (MyBPC1), which are critically involved in muscle differentiation and maintenance, and have been implicated in the pathogenesis of severe myopathies. Biochemical analyses demonstrated that MyBPC1 is a short-lived proteasomal substrate, and its degradation is prevented by over-expression of USP25m but not by other USP25 isoforms. In contrast, ACTA1 and FLNC appear to be stable proteins, indicating that their interaction with USP25m is not related to their turnover rate. Received 7 November 2005; received after revision 7 January 2006; accepted 13 January 2006     

An Adaptive Identification and Control Scheme Using Radial Basis Function Networks

1.INTaODUCTIONThemultilayerfeedforwardneuralnetworks(MFNN)hasbeenwidelyappliedinmanyfieldssuchaspatternrecognition,nonlinearoptimization,systemidentificationandcontrol.Thesimpleback-propagation(BP)learningalgorithmisusuallyadoptedtoupdateitsweights.TheBPalgorithm,however,suffersdrawbacksofslowconvergenceandunpredictablesolutionsduringlearning.Althoughmailyapproachessuchasvariablestepsize,conjugategradient,pseudo-Newtonmethods[4]andothermethods[3,10],havebeendevelopedtoovercometheproble…     

植物标签技术

传统的正向遗传学主要用于克隆表型或功能已确定的基因。转座子标签突变体可用随机标签法从带有活性转座子的自交后代中筛选得到,或用定向标签法从杂交一代中筛选得到,即用目的基因的隐性突变统合体与具高度活性转座号的统合体杂交,极大多数的FI个体为正常表型,但其中会有极少量的表现隐性性状的转庄子插入突变体。正向基因标签和克隆法在利用异源和低拷贝数品系时尤其有用。采用反向fCR或热不对称交替PCR（TAIL－PCR）且很容易从单拷贝或低拷贝数品系中获得插入于两侧的基因组序列。TAIL－PCR由三轮连续的半巢式PCR组成,所…     

影响林木种子贮藏的因素

为了每年提供造林新需的具有生活力的种子及长期保存种质资源,贮藏种子是必要的手段。种子寿命具有遗传性,且因树种而异。种子的贮藏特性可以分成5类:正常型、亚正常型、温带顽拗型、热带顽拗型和中间型。种子含水量和贮藏温度是影响种子贮藏是否成功的两个最重要因素。但因树种及其贮藏特性不同,种子含水量和贮藏温度的最适值也不同。为了保持正常型和亚正常型种子的生活力,这类种子必须密封贮藏;但对顽拗型种子,因其需要保持种子的代谢活性及要进行有氧呼吸,则需要气体交换。     

关于Quarter可层化空间

对第二纲的仿紧Quarter可层化空间进行了研究,证明了这类空间含有σ闭离散的稠密子集. 同时给出了实数集的子集是消去拓扑半群,但是不是Quarter可层化空间.     

基于收益-风险模型分析高校学生在线健康咨询服务使用意愿的影响因素

目的:研究高校学生在线健康咨询服务使用意愿的影响因素.方法:采用方便抽样,使用"问卷星"设计和制作调查问卷,并对成都市两所大学的500名大学生进行问卷调查,使用结构方程模型对在线健康咨询服务使用意愿的影响因素进行分析.结果:问卷回收443份,回收率为88.40%,有效442份,有效率为99.77%.感知收益(β=0.368,P<0.001)、网络信任(β=0.147,P<0.05)和医生信任(β=0.129,P<0.05)正向影响使用意愿;感知风险(β=-0.018,P>0.05)、平台信任(β=0.141,P>0.05)对使用意愿的直接影响未得到支持;网络信任和医生信任在感知风险与使用意愿的关系间具有完全中介作用,在感知收益与使用意愿的关系间发挥部分中介作用.结论:增加公众对网络环境和网上医生的信任以及提高患者潜在的利益是提高在线健康咨询服务的使用意愿的关键.