The S receptor kinase determines self-incompatibility in Brassica stigma

The self-incompatibility possessed by Brassica is an intraspecific reproductive barrier by which the stigma rejects self-pollen but accepts non-self-pollen for fertilization. The molecular/biochemical bases of recognition and rejection have been intensively studied. Self-incompatibility in Brassica is sporophytically controlled by the polymorphic S locus. Two tightly linked polymorphic genes at the S locus, S receptor kinase gene (SRK) and S locus glycoprotein gene (SLG), are specifically expressed in the papillar cells of the stigma, and analyses of self-compatible lines of Brassica have suggested that together they control stigma function in self-incompatibility interactions. Here we show, by transforming self-incompatible plants of Brassica rapa with an SRK28 and an SLG28 transgene separately, that expression of SRK28 alone, but not SLG28 alone, conferred the ability to reject self (S28)-pollen on the transgenic plants. We also show that the ability of SRK28 to reject S28 pollen was enhanced by SLG28. We conclude that SRK alone determines S haplotype specificity of the stigma, and that SLG acts to promote a full manifestation of the self-incompatibility response.     

An SCF-like ubiquitin ligase complex that controls presynaptic differentiation

During synapse formation, specialized subcellular structures develop at synaptic junctions in a tightly regulated fashion. Cross-signalling initiated by ephrins, Wnts and transforming growth factor-beta family members between presynaptic and postsynaptic termini are proposed to govern synapse formation. It is not well understood how multiple signals are integrated and regulated by developing synaptic termini to control synaptic differentiation. Here we report the identification of FSN-1, a novel F-box protein that is required in presynaptic neurons for the restriction and/or maturation of synapses in Caenorhabditis elegans. Many F-box proteins are target recognition subunits of SCF (Skp, Cullin, F-box) ubiquitin-ligase complexes. fsn-1 functions in the same pathway as rpm-1, a gene encoding a large protein with RING finger domains. FSN-1 physically associates with RPM-1 and the C. elegans homologues of SKP1 and Cullin to form a new type of SCF complex at presynaptic periactive zones. We provide evidence that T10H9.2, which encodes the C. elegans receptor tyrosine kinase ALK (anaplastic lymphoma kinase), may be a target or a downstream effector through which FSN-1 stabilizes synapse formation. This neuron-specific, SCF-like complex therefore provides a localized signal to attenuate presynaptic differentiation.     

A kinase-regulated PDZ-domain interaction controls endocytic sorting of the beta2-adrenergic receptor.

A fundamental question in cell biology is how membrane proteins are sorted in the endocytic pathway. The sorting of internalized beta2-adrenergic receptors between recycling endosomes and lysosomes is responsible for opposite effects on signal transduction and is regulated by physiological stimuli. Here we describe a mechanism that controls this sorting operation, which is mediated by a family of conserved protein-interaction modules called PDZ domains. The phosphoprotein EBP50 (for ezrinradixin-moesin(ERM)-binding phosphoprotein-50) binds to the cytoplasmic tail of the beta2-adrenergic receptor through a PDZ domain and to the cortical actin cytoskeleton through an ERM-binding domain. Disrupting the interaction of EBP50 with either domain or depolymerization of the actin cytoskeleton itself causes missorting of endocytosed beta2-adrenergic receptors but does not affect the recycling of transferrin receptors. A serine residue at position 411 in the tail of the beta2-adrenergic receptor is a substrate for phosphorylation by GRK-5 (for G-protein-coupled-receptor kinase-5) and is required for interaction with EBP50 and for proper recycling of the receptor. Our results identify a new role for PDZ-domain-mediated protein interactions and for the actin cytoskeleton in endocytic sorting, and suggest a mechanism by which GRK-mediated phosphorylation could regulate membrane trafficking of G-protein-coupled receptors after endocytosis.     

甘蓝型油菜BnTR1和ATP6之间相互作用的研究

为进一步研究ATP6和BnTR1之间的相互作用及具体作用位点,通过构建含不同长度的BnTR1 cDNA序列的pGADT7融合载体,利用酵母双杂交证明了BnTR1的C端92～202位氨基酸序列与ATP6的氨基酸序列具有相互作用.     

Direct homeodomain-DNA interaction in the autoregulation of the fushi tarazu gene.

A major problem in the elucidation of the molecular mechanisms governing development is the distinction between direct and indirect regulatory interactions among developmental control genes. In vivo studies have indicated that the Drosophila segmentation gene fushi tarazu (ftz) directly or indirectly autoregulates its expression. Here we describe a generally applicable experimental approach which establishes a direct in vivo interaction of the homeodomain protein ftz with the ftz cis-autoregulatory control region. In vitro studies have shown that the DNA-binding specificity of the ftz homeodomain can be changed by a single amino-acid substitution in the recognition helix (Gln 50----Lys). Whereas wild-type ftz homeodomain binds preferentially to a CCATTA motif, the mutant homeodomain (ftzQ50K) recognizes a GGATTA motif. We now find that the in vivo activity of an ftz autoregulatory enhancer element is reduced by mutations of putative ftz-binding sites to GGATTA. This down-regulatory effect is specifically suppressed in vivo by the DNA-binding specificity mutant ftzQ50K. These results establish a direct positive autoregulatory feedback mechanism in the regulation of this homeobox gene.     

基于直接测量的水合物储层颗粒间作用力测试系统与测试方法

针对水合物储层失稳和出砂行为力学机制的微观刻画难题,开发一种基于直接测量储层颗粒间作用力的微力测量装置,并提出相应的测试方法,通过对比前人水滴、冰颗粒和水合物颗粒间的黏附力测试结果,验证装置的准确性,进而开展冰颗粒、四氢呋喃(tetrahydrofuran,THF)水合物颗粒与南海砂之间的摩擦力测试.结果表明,冰和TH...     

少学时互动启发式教学研究及复杂铰问题探索

《工程力学》一直是高等院校工科类各专业的一门重要的专业基础课.该课程涵盖的知识点多,公理、定理、概念和公式多,且与生产生活实践密切联系,有好多问题直接来源于实践,但是由于受学时限制,学生普遍认为《工程力学》课程太难,以至丧失学习兴趣,于是面临如此窘况,互动启发式教学应运而生.由于受教学启发,该文就静力学受力分析中,复杂铰在复杂结构中的受力分析进行研究.该文提出一种复杂铰受力分析的新方法,即"截断节点分析法".该方法通过对复杂铰链进行全部拆分,确定铰链中各构件及销钉之间的拉压力关系,进而能够对杆件及销钉进行准确高效的受力分析,起到加深对复杂铰理解和提高解题效率的效果.     

新型三苯胺-卟啉锌复合物与DNA的结合模式及单线态氧能力研究

本研究合成三苯胺-卟啉锌复合物(ZnTPor)和PEG-四苯卟啉化合物(PPor),并利用紫外-可见光吸收光谱、荧光发射光谱研究他们与DNA的结合模式.发现两种卟啉化合物均能与DNA有较好结合,PPor为外部结合模式,ZnTPor为嵌插结合模式.ZnTPor、PPor与ct-DNA的结合常数分别为2.17×10~6和2.63×10~5(L/mol).也进行了两种化合物的单线态氧测试,结果表明,单线态氧产生效率ZnTPor PPor.这些研究为后续光动力、光热治疗研究奠定一定的理论基础.     

SCTE: RCS prediction system for complex target and interaction with environment

A RCS prediction system named SCTE (Scattering from Complex Target and Environment) for calculating high-frequency electromagnetic scattering from complex target within complex environment is presented. The scattering body is described by Computer-Aided-Design (CAD) representations in which the complex body is modeled as NURBS (Non-Uniform Rational B-spline) surfaces. The complex environment (rough surface of sea or ground) is also carefully considered by using fractal function. Scattering fields are calculated by using physical optics and the equivalent currents methods. There is a good agreement between the present results and that from measurements which demonstrates the accuracy of this system. Foundation item: Supported by the National Natural Science Foundation of China Biography: CAO Qin-feng (1972-) male, Ph.D. candidate.     

基于Scatchard法的碳酸酐酶-脂质体与药物结合常数测定

 为更好地模拟药物小分子与碳酸酐酶在体内的相互作用,采用碳酸酐酶-脂质体毛细管电泳法,以4-羧基苯磺酰胺为分析对象建立碳酸酐酶药物筛选模型,并以此模型为基础计算12 种药物小分子与碳酸酐酶的结合常数,分析药物小分子与碳酸酐酶的相互作用。结果表明,4-羧基苯磺酰胺与碳酸酐酶-脂质体的结合常数为1.172×10⁴ mL·g^-1,具有较强的相互作用。基于此,筛选出4 种(咖啡酸、L-抗坏血酸、2, 4-二氯-5-磺酰胺基苯甲酸和4-氯-3-磺酰胺基苯甲酸)和5种(阿魏酸、马兜铃酸、没食子酸、原儿茶酸、烟酸)与复合物具有较强或较弱相互作用的药物。通过该法可快速、有效、经济地测定碳酸酐酶或其他靶标与药物的相互作用,缩短药物研发周期。     

Analysis of correlations between protein complex and protein-protein interaction and mRNA expression

Protein-protein interaction is a physical interaction of two proteins in living cells. In budding yeast Saccharomyces cerevisiae, large-seale protein-protein interaction data have been obtained through high-throughput yeast two-hybrid systems (Y2H) and protein complex purification techniques based on mass-spectrometry. Here, we collect 11855 interactions between total 2617 proteins. Through seriate genome-wide mRNA expression data, similarity between two genes could be measured. Protein complex data can also be obtained publicly and can be translated to pair relationship that any two proteins can only exist in the same complex or not. Analysis of protein complex data, protein-protein interaction data and mRNA expression data can elucidate correlations between them. The results show that proteins that have interactions or similar expression patterns have a higher possibility to be in the same protein complex than randomized selected proteins, and proteins which have interactions and similar expression patterns are even more possible to exist in the same protein complex. The work indirates that comprehensive integration and analysis of public large-seale bioinformatical data, such as protein complex data, protein-protein interaction data and mRNA expression data, may help to uncover their relationships and common biological information underlying these data. The strategies described here may help to integrate and analyze other functional genomic and proteomic data, such as gene expression profiling, protein-localization mapping and large-scale phenotypic data, both in yeast and in other organisms.     

六氮杂镍配合物与DNA相互作用的研究

合成了六氮杂镍的配合物(Ni(Ⅱ)L-1,8-二羟基乙基-1,3,6,8,10,13-六氮十四烷高氯酸镍).用电化学、荧光光谱及黏度等方法研究了配合物与小牛胸腺DNA(ct-DNA)的相互作用.电化学实验表明,Ni(Ⅱ)L在Tris-HCl缓冲溶液(pH=7.3)中的氧化还原是1电子转移过程,Ni(Ⅱ)和Ni(Ⅲ)配合物对DNA键合常数的比值(K2 /K3 )为3.2;荧光实验表明该配合物与DNA具有明显的嵌插作用,其结合常数为2.15×104L/mol;黏度实验表明Ni(Ⅱ)L可使DNA发生卷曲或扭结作用.实验均表明Ni(Ⅱ)L和DNA相互作用为部分嵌插和部分沟谷结合的混合模式.在H2O2存在下,凝胶电泳和高效液相色谱方法证明Ni(Ⅱ)L对ct-DNA和pBR322 DNA的劈裂能力均增强.     

Fe(phen)3Cl3的合成及其与DNA作用的光谱性质

合成了Fe(phen)3Cl3，进行了红外表征，证实其结构，并以不同的参比研究了Fe(phen)3Cl3与DNA作用的分子光谱，认为Fe(phen)3Cl3与DNA作用的方式主要以插入的结合方式为主，当DNA的浓度增大，同时伴随有静电结合。     

血红蛋白在戊二醛膜修饰金电极上的直接电化学行为及其与氨茶碱的相互作用

用直接滴涂法将血红蛋白（Hb）固定到戊二醛（GA）膜修饰的金电极表面,通过循环伏安法研究了Hb在GA膜修饰金电极上的直接电化学行为.在0.1 mol/L磷酸盐缓冲溶液（PBS,pH 6.00）中,扫描速度为100mV/s时,该修饰电极的峰电位差ΔE=44 mV,氧化还原峰电流之比Ip,a/Ip,c=1.17,说明Hb在GA膜修饰电极上的氧化还原过程是可逆过程;随着缓冲溶液pH值的增大,其峰电位不变,而峰电流呈增大（pH=4.00～6.00）或减小（pH=6.00～8.00）的趋势.通过GA膜对Hb的吸附固定,不仅保持了Hb的生物活性,而且实现了Hb与电极之间的直接电子转移.利用此修饰电极,研究了Hb与药物氨茶碱之间的相互作用,求得Hb和氨茶碱的结合数为2.     

复杂岩溶区溶洞储水与隧道衬砌相互作用

水压衬砌的稳定性研究仍是在富水区修建隧道工程所关注的重点问题。多数相关研究均是基于连续性"渗透"模型和Darcy定理的基础上开展的。基于前人研究成果,结合实际情况,发现工程中衬砌主要破坏原因区别于渗流破坏,进而确认该隧道支护结构破坏主要原因为隧道排水系统失效后短时间内衬砌背后溶洞储水作用下的变高水头水压致裂破坏,从而提出该力学模型为"荷载-结构"模型,而"荷载-结构"模型的关键问题在于确定衬砌所受岩溶水压力大小与分布形式。根据水文地质条件假定溶洞处于汇水期时其流量基本不变,结合工程地质条件推导了该工程区两类溶洞("走向型"溶洞和"斜交型"溶洞)的体积计算公式,再换算确定不同时间范围内的储水体积,最后折算为衬砌所受应力边界条件。通过数值计算理论分析变水压下隧道的力学响应特点,通过与现场照片的对比可证明隧道衬砌破坏主要原因确为水压致裂,同时伴有一定的水体渗透、劈裂作用加剧失效,说明前述的假设研究具有一定合理性,针对研究结果对工程提出了防范措施要点。研究思路与理论研究成果可为类似工程提供借鉴与参考。     

一种希夫碱铜配合物与DNA相互作用的研究

设计合成一种希夫碱2-氨基-5-巯基-1,3,4-噻二唑水杨亚胺(L)及其铜的配合物Cu(L),运用红外、紫外、元素分析等方法对其结构进行表征.同时在pH=7.5的三羟甲基氨基甲烷-盐酸缓冲溶液(Tris-HCl)中用荧光光谱法研究了该配合物Cu(L)与DNA的相互作用,结果发现配合物Cu(L)与DNA的作用模式是插入式模式,测得Cu(L)与DNA的结合常数为K=2.0×104mol.L-1,线性相关系数r=0.999 5,并且还用不同的离子强度和不同的浓度[Fe(CN)6]4-对Cu(L)配合物与DNA体系的荧光光谱的影响情况进行研究,从而进一步论证了其相互作用模式是插入式.