非洲爪蟾Brunol和MCPH基因在早期胚胎发育过程中表达的研究及随机定向酵母双杂交cDNA文库的构建

BRUNOL/CELF家族RNA结合蛋白在转录后调控（post-transcriptional regulation）中起着至关重要的作用，参与多种组织的发育过程。本研究中，我们描述了非洲爪蟾5个Brunol 基因的克隆与表达。其中只有Brunol2是母源性以及合子表达的，其它的4个Brunol基因都是合子表达的，但起始表达的发育时期有所不同。爪蟾发育过程中，Brunol1、4和5基因特异性地在神经系统中表达，包括脑、脊髓、眼泡和耳泡。Brunol2和3基因在体节中胚层与神经系统表达。Brunol2也在晶状体中有非常高的表达。在转染的Hela细胞中，BRUNOL1、2和3蛋白定位于细胞质和细胞核中，BRUNOL4和5只是定位于细胞质中，显示它们具有不同的功能。 人的microcephalin1（MCPH1）基因的遗传突变产生原发性小头症，而在人类的进化过程中，这个基因的变化可能对人脑体积的增加和认知能力的增强也起到重要的作用。但是对于MCPH基因在其它物种中功能的研究才刚刚开始。我们克隆了非洲爪蟾MCPH基因，发现非洲爪蟾具有A，B两个同源基因，其功能域的保守性较高，暗示非洲爪蟾MCPH基因仍然执行一些保守的功能，但MCPHB由于突变只编码一种截短的蛋白，目前尚不清楚它是否是有功能的。胚胎原位杂交的结果显示MCPHA，B基因在胚胎发育中的表达图式相似，但MCPHB的表达水平较低。在神经胚期，二者均表达于头部基板区，在尾芽期主要表达于咽鳃区，而在脑区的表达并不显著，与小鼠中的表达模式不同，提示在爪蟾中MCPH基因可能主要参与咽鳃区而不是脑的发育。 为了进一步筛选这些蛋白可能的结合因子，我们构建了非洲爪蟾双杂交cDNA文库。其中利用修饰的随机引物和特别设计的连接头在合成双链cDNA时，在下游合成一个SalI限制性酶切位点，可以将cDNA定向插入载体。通过对于空克隆率和插入片段长度等一系列参数的分析，表明这个定向cDNA文库的构建是成功的。

小麦中微量元素锌铁硒的含量的分析

本研究应用微波消解ICP-AES 法对62 个小麦品种及3 个地区土壤的锌铁硒含量进行了分析测定，发现不同小麦品种中微量元素含量差异很大，姊妹系间也存在差异。含铁量最高与最低的小麦品种铁含量相差29.68mg/kg。含锌量最高与最低的小麦品种锌含量相差46.70 mg/kg。含硒量最高与最低的小麦品种硒含量相差0.056 mg/kg。对不同地点的小麦及土壤中锌铁硒含量进行方差分析，发现双流和西昌两地种植小麦的铁含量和硒含量均有显著差异，西昌和荣县种植的锌含量有显著差异。在3 个地点中双流种植小麦硒含量最高，西昌种植小麦的铁和锌含量最高。 通过对小麦微量元素含量与土壤中微量元素含量进行了相关性分析，结果表明：小麦中的锌铁含量与土壤中的锌铁含量呈显著正相关，土壤中铁与锌含量呈极显著正相关，小麦中铁与锌含量也呈极显著正相关。随着土壤微量元素锌铁的提高，小麦中的锌铁元素含量同时提高，而且小麦对两种元素的吸收互相促进。土壤中的硒含量与锌铁含量呈负相关。小麦中硒含量也与锌铁含量也呈负相关。说明锌和铁与硒互相拮抗。小麦硒含量与土壤硒含量呈正相关，但不显著。表明土壤硒含量可以影响小麦硒含量，但不是决定因素，小麦硒含量与小麦自身因素有关。 对姊妹系G290（高硒含量）和G289（低硒含量）进行抗重金属胁迫和抗旱性实验发现，高硒品种G290的抗逆性优于低硒品种G289。 利用RAPD 技术对7 个姊妹系进行遗传差异分析发现，高硒材料G290出现了特异条带，分别标为1、2、3、4，其他姊妹系品种中未发现特异条带，回收4 条特异条带并连接转化，得到目的片段1、2、3 的重组子，进行测序。NCBI 中结果显示没有找到植物中的同源序列，说明特异序列可能是未发现的基因片段，推测可能与小麦硒含量有关，有待进一步研究。 以上研究结果，对小麦营养研究及功能性小麦的筛选和栽培具有指导作用。 In this study, we determinated the contents of zinc, iron, selenium in 62 wheat cultivars and soil samples of three regions by method of microwave digestion/ ICPAES,found that there was great difference of zinc, iron, selenium contents in different wheat cultivars as well as different sister lines. Iron content difference was 29.68 mg/kg between the highest-iron-content cultivar and the lowest one, and zinc content difference was 46.70 mg/kg , selenium content difference was 0.056 mg/kg. Anova analysis was made on contents of zinc, iron, selenium in wheat and soil samples of different locations, significant differences of Fe and Se contents were found between wheat in Shuangliu and Xichang, significant difference of Zn content was found between wheat in Xichang and Rongxian. Se content in wheat of Shuangliu was highest, Fe and Zn contents in wheat of Xichang were highest. Relativity analysis was made on three trace elements in Wheat and in soil, the result showed that there was significant positive correlation of zinc, iron content between in Wheat and in soil, as well as between Fe and Zn both in wheat and in soil. With the improving of Zn, Fe contents in soil, contents of Zn and Fe in wheat increased and absorption of Zn and Fe in wheat will mutual promote. Negative correlation of Se and Zn contents was found in wheat and soil, but not significant, that meant the antagonism of Se and Zn. Positive correlation of Se content in wheat and soil was found. High selenium content G290 and low selenium content G289 in sister lines were selected for heavy metal stress and drought resistance experiments, the result showed that the resistance of high-selenium-content cultivar was better than low selenium one. Analysis on genetic difference was made by RAPD, and specific bands were selected, marked 1,2,3,4, no more specific bands were found in other sister lines.4 bands were recovered, ligated to T-vector and transformed E.coli. Three recombinant plasmids were obtained and sequenced. NCBI Blast showed there was no homology with other plants. It implied that these fragments probably be new genes and maybe were related to selenium in wheat. It needs further research. This paper would be useful for the study of wheat nutrition as well as selection and cultivation of functional wheat.

Experimental study on the electric-sweep scanner and ion beam emittance of electron cyclotron resonance ion source

With a latest developed electric-sweep scanner system, we have done a lot of experiments for studying this scanner system and ion beam emittance of electron cyclotron resonance (ECR) ion source. The electric-sweep scanner system was installed on the beam line of Lanzhou electron resonance ion source No. 3 experimental platform of Institute of Modem Physics. The repetition experiments have proven that the system is a relatively dependable and reliable emittance scanner, and its experiment error is about 10%. We have studied the influences of the major parameters of ECR ion source on the extracted ion beam emittance. The typical results of the experiments and the conclusions are presented in this article.

Biomolecule-nanoparticle hybrids for electrochemical biosensors

Inorganic nanoparticles (NPs) with attractive electronic, optical, magnetic, thermal and catalytic properties have attracted great interest due to their important applications in physics, chemistry, biology, medicine, materials science and interdisciplinary fields. Biomolecule-NP hybrid systems, which combine recognition and catalytic properties of biomolecules with electronic, optical, magnetic and catalytic properties of NPs, are particularly new materials with synergistic properties originating from the components of the hybrid composites. The biomolecule-NP hybrid system has excellent prospects for interfacing biological recognition events with electronic signal transduction so as to design a new generation of bioelectronic devices with high sensitivity.

Novel prefractionation method can be used in proteomic analysis

For the first time, a novel prefractionation method used in proteomic analysis was developed, which is performed by a novel aqueous two-phase system (NATPS) composed of n-butanol, (NH4)(2)SO4, and water. It can separate proteomic proteins into multigroups by one-step extraction. The phase-separation conditions of n-butanol solutions were studied in the presence of commonly used inorganic salts. The NATPS was subsequently developed. Using human serum albumin, zein, and gamma-globulin as model proteins, the separation effectiveness of the NATPS for protein was studied under affection factors, i.e., pH, n-butanol volume, protein, or salt concentration. The model and actual protein samples were separated by the NATPS and then directly used for gel electrophoresis without separating the target proteins from phase-forming reagents. It revealed that the NATPS could separate proteomic proteins into multigroups by one-step extraction. The NATPS has the advantages of rapidity, simplicity, low cost, biocompability, and high efficiency. It need not separate target proteins from the phase-forming reagents. The NATPS has great significance in separation and extraction of proteomic proteins, as well as in methodology.

Novel polyoxometalate-templated, 3-D supramolecular networks based on lanthanide dimers: Synthesis, structure, and fluorescent properties of [Ln(2)(DNBA)(4)(DMF)(8)][Mo6O19] (DNBA=3,5-dinitrobenzoate)

The spherical Lindquist type polyoxometalate, Mo6O192-, has been used as a noncoordinating anionic template for the construction of novel three-dimensional lanthanide-aromatic monocarboxylate dimer supramolecular networks [Ln(2)(DNBA)(4)(DMF)(8)][Mo6O19] (Ln = La 1, Ce 2, and Eu 3, DNBA = 3,5-dinitrobenzoate, DMF = dimethylformamide). The title compounds are characterized by elemental analyses, IR, and single-crystal X-ray diffractions. X-ray diffraction experiments reveal that two Ln(III) ions are bridged by four 3,5-dinitrobenzoate anions as asymmetrically bridging ligands, leading to dimeric cores, [Ln(2)(DNBA)(4)(DMF)(8)](2+); [Ln(2)(DNBA)(4)(DMF)(8)](2+) groups are joined together by pi-pi stacking interactions between the aromatic groups to form a two-dimensional grid-like network; the 2-D supramolecular layers are further extended into 3-D supramolecular networks with 1-D box-like channels by hydrogen-bonding interactions, in which hexamolybdate polyanions reside. The compounds represent the first examples of 3-D carboxylate-bridged lanthanide dimer supramolecular "host" networks formed by pi-pi stacking and hydrogen-bonding interactions encapsulating noncoordinating "guest" polyoxoanion species. The fluorescent activity of compound 3 is reported.

Confined crystallization behavior of PEO in silica networks

Poly(ethylene oxide) (PEO) and silica (SiO2) organic-inorganic hybrid materials have been synthesized by sol-gel approach. The crystallization behavior of PEO in silica networks has been investigated by differential scanning calorimeter (DSC) and scanning electron micrograph (SEM). The degree of PEO crystallinity in PEO/SiO2 hybrid networks reduces with the increase of SiO2. PEO is in amorphous state when the concentration of PEO is lower than 50 wt% in the hybrid materials. The melting points of PEO in the networks are lower than that of pure PEG, but the melting point of PEO in the networks almost has the same melting point. WAXD and SEM results show that the crystalline behavior of PEO in PEO/SiO2 hybrid system is sternly confined. (C) 1999 Elsevier Science Ltd. All rights reserved.

Interfacial layer and phase inversion behavior in the blend of polyethersulfone and polycarbonate

A blend of polyethersulfone (PES) and polycarbonate (PC) with a ratio of 40/60 was studied by scanning electron microscopy (SEM), dynamic mechanical analysis, and transmission electron microscopy (TEM). It was found that the PES-PC blend is a partially miscible, two-phase system, and an interfacial layer exists between the phases of PES and PC. Specific interaction resulting from the n-complex between PES and PC provides the driving force for formation of the interfacial layer. In addition, phase inversion behavior was also observed for the 40/60 composition.

SAXS measurements of the interface in polyacrylate and epoxy interpenetrating networks with fractal geometry

The interface thickness in two-component interpenetrating polymer networks (IPN) system based on polyacrylate and epoxy were determined using small-angle X-ray scattering (SAXS) in terms of the theory proposed by Ruland. The thickness was found to be nonexistent for the samples at various compositions and synthesized at variable conditions-temperature and initiator concentration. By viewing the system as a two-phase system with a sharp boundary, the roughness of the interface was described by fractal dimension, D, which slightly varies with composition and synthesis condition. Length scales in which surface fractals are proved to be correct exist for each sample and range from 0.02 to 0.4 Angstrom(-1). The interface in the present IPN system was treated as fractal, which reasonably explained the differences between Pored's law and experimental data, and gained an insight into the interaction between different segments on the interface. (C) 1997 Elsevier Science Ltd.

Genome-wide survey of putative serine/threonine protein kinases in cyanobacteria

Background: Serine/threonine kinases (STKs) have been found in an increasing number of prokaryotes, showing important roles in signal transduction that supplement the well known role of two-component system. Cyanobacteria are photoautotrophic prokaryotes able to grow in a wide range of ecological environments, and their signal transduction systems are important in adaptation to the environment. Sequence information from several cyanobacterial genomes offers a unique opportunity to conduct a comprehensive comparative analysis of this kinase family. In this study, we extracted information regarding Ser/Thr kinases from 21 species of sequenced cyanobacteria and investigated their diversity, conservation, domain structure, and evolution. Results: 286 putative STK homologues were identified. STKs are absent in four Prochlorococcus strains and one marine Synechococcus strain and abundant in filamentous nitrogen-fixing cyanobacteria. Motifs and invariant amino acids typical in eukaryotic STKs were conserved well in these proteins, and six more cyanobacteria- or bacteria-specific conserved residues were found. These STK proteins were classified into three major families according to their domain structures. Fourteen types and a total of 131 additional domains were identified, some of which are reported to participate in the recognition of signals or substrates. Cyanobacterial STKs show rather complicated phylogenetic relationships that correspond poorly with phylogenies based on 16S rRNA and those based on additional domains. Conclusion: The number of STK genes in different cyanobacteria is the result of the genome size, ecophysiology, and physiological properties of the organism. Similar conserved motifs and amino acids indicate that cyanobacterial STKs make use of a similar catalytic mechanism as eukaryotic STKs. Gene gain-and-loss is significant during STK evolution, along with domain shuffling and insertion. This study has established an overall framework of sequence-structure-function interactions for the STK gene family, which may facilitate further studies of the role of STKs in various organisms.

Genome-wide survey of putative serine/threonine protein kinases in cyanobacteria

Background: Serine/threonine kinases (STKs) have been found in an increasing number of prokaryotes, showing important roles in signal transduction that supplement the well known role of two-component system. Cyanobacteria are photoautotrophic prokaryotes able to grow in a wide range of ecological environments, and their signal transduction systems are important in adaptation to the environment. Sequence information from several cyanobacterial genomes offers a unique opportunity to conduct a comprehensive comparative analysis of this kinase family. In this study, we extracted information regarding Ser/Thr kinases from 21 species of sequenced cyanobacteria and investigated their diversity, conservation, domain structure, and evolution. Results: 286 putative STK homologues were identified. STKs are absent in four Prochlorococcus strains and one marine Synechococcus strain and abundant in filamentous nitrogen-fixing cyanobacteria. Motifs and invariant amino acids typical in eukaryotic STKs were conserved well in these proteins, and six more cyanobacteria- or bacteria-specific conserved residues were found. These STK proteins were classified into three major families according to their domain structures. Fourteen types and a total of 131 additional domains were identified, some of which are reported to participate in the recognition of signals or substrates. Cyanobacterial STKs show rather complicated phylogenetic relationships that correspond poorly with phylogenies based on 16S rRNA and those based on additional domains. Conclusion: The number of STK genes in different cyanobacteria is the result of the genome size, ecophysiology, and physiological properties of the organism. Similar conserved motifs and amino acids indicate that cyanobacterial STKs make use of a similar catalytic mechanism as eukaryotic STKs. Gene gain-and-loss is significant during STK evolution, along with domain shuffling and insertion. This study has established an overall framework of sequence-structure-function interactions for the STK gene family, which may facilitate further studies of the role of STKs in various organisms.

Interaction between Thymidylate Synthase and Its Cognate mRNA in Zebrafish Embryos

Thymidylate synthase (TS), which catalyzes the de novo synthesis of dUMP, is an important target for cancer therapy. In this report, the effects of 5-fluorouracil (5-FU) and ZD1694 on the regulation of TS gene expression were evaluated in zebrafish embryos. Our results revealed that the expression of TS was increased by about six-fold when embryos were treated with 1.0 mu M 5-FU and there was a greater than 10-fold increase in the TS protein level after treatment with 0.4 mu M ZD1694. Northern blot analysis confirmed that expression of TS mRNA was identical in treated or untreated embryos. Gel shift and immunoprecipitation assays revealed that zebrafish TS was specifically bound with its cognate mRNA in vitro and in vivo. We identified a 20 nt RNA sequence, TS:N20, localized to the 5'-UTR of TS mRNA, which corresponded to nt 13-32; TS:N20 bound to the TS protein with an affinity similar to that of the full-length TS mRNA. The MFold program predicted that TS:N20 formed a stable stem-loop structure similar to that of the cis-acting element found in human TS mRNA. Variant RNAs with either a deletion or mutation in the core motif of TS:N20 were unable to bind to the TS protein. In vitro translation experiments, using the rabbit lysate system, confirmed that zebrafish TS mRNA translation was significantly repressed when an excess amount of TS protein was included in the system. Additionally, a TS stability experiment confirmed that treatment of zebrafish embryos with 5-FU could increase the TS stability significantly, and the half life of TS protein was about 2.7 times longer than in untreated embryos. Our study revealed a structural requirement for the interaction of TS RNA with TS protein. These findings also demonstrated that the increase in TS protein induced by 5-FU occurs at the post-transcriptional level and that increased stability and translation efficiency both contributed to the increase in TS protein levels induced by TS inhibitors.

Interaction between Thymidylate Synthase and Its Cognate mRNA in Zebrafish Embryos

Thymidylate synthase (TS), which catalyzes the de novo synthesis of dUMP, is an important target for cancer therapy. In this report, the effects of 5-fluorouracil (5-FU) and ZD1694 on the regulation of TS gene expression were evaluated in zebrafish embryos. Our results revealed that the expression of TS was increased by about six-fold when embryos were treated with 1.0 mu M 5-FU and there was a greater than 10-fold increase in the TS protein level after treatment with 0.4 mu M ZD1694. Northern blot analysis confirmed that expression of TS mRNA was identical in treated or untreated embryos. Gel shift and immunoprecipitation assays revealed that zebrafish TS was specifically bound with its cognate mRNA in vitro and in vivo. We identified a 20 nt RNA sequence, TS:N20, localized to the 5'-UTR of TS mRNA, which corresponded to nt 13-32; TS:N20 bound to the TS protein with an affinity similar to that of the full-length TS mRNA. The MFold program predicted that TS:N20 formed a stable stem-loop structure similar to that of the cis-acting element found in human TS mRNA. Variant RNAs with either a deletion or mutation in the core motif of TS:N20 were unable to bind to the TS protein. In vitro translation experiments, using the rabbit lysate system, confirmed that zebrafish TS mRNA translation was significantly repressed when an excess amount of TS protein was included in the system. Additionally, a TS stability experiment confirmed that treatment of zebrafish embryos with 5-FU could increase the TS stability significantly, and the half life of TS protein was about 2.7 times longer than in untreated embryos. Our study revealed a structural requirement for the interaction of TS RNA with TS protein. These findings also demonstrated that the increase in TS protein induced by 5-FU occurs at the post-transcriptional level and that increased stability and translation efficiency both contributed to the increase in TS protein levels induced by TS inhibitors.

Feeding and growth on bivalve biodeposits by the deposit feeder Stichopus japonicus Selenka (Echinodennata : Holothuroidea) co-cultured in lantern nets

Suspension aquaculture of filter-feeding bivalves has been developing rapidly in coastal waters in the world, especially in China. Previous studies have demonstrated that dense populations of filter-feeding bivalves in shallow water can produce a large amount of faeces and pseudofaeces (biodeposits) that may lead to negative impacts on the benthic environment. To determine whether the deposit feeder Stichopus (Apostichopus) japonicus Selenka can feed on bivalve biodeposits and whether the sea cucumber can be co-cultured with bivalves in suspended lantern nets, three experiments were conducted, two in tanks in the laboratory and one in the field. In a 3-month flow-through experiment, results showed that sea cucumbers grew well with specific growth rate (SGR) reaching 1.38% d(-1), when cultured in the bottom of tanks (10 m(3) water volume) where scallops were cultured in suspension in lantern nets. Moreover, results of another laboratory experiment demonstrated that sea cucumbers could survive well on bivalve biodeposits, with a feeding rate of 1.82 +/- 0.13 g dry biodeposits ind(-1) d(-1), absorption efficiency of organic matter in biodeposits of 17.2% +/- 5.5%, and average SGR of 1.60% d(-1). Our longer-term field experiments in two coastal bays (Sishili Bay and Jiaozhou Bay, northern China) showed that S. japonicus co-cultured with bivalves also grew well at growth rates (0.09-0.31 g wet weight ind(-1) d(-1)) depending on individual size. The results suggest that bivalve lantern nets can provide a good habitat for sea cucumbers; and the co-culture of bivalve molluscs with sea cucumbers may provide an additional valuable crop with no additional inputs. (c) 2006 Elsevier B.V. All rights reserved.

星球探测系统的多机器人组内协作研究

建立了子机器人的控制模型,提出了分散式控制与集中式控制相结合的复合控制体系。采用动态分配ID号和由ID号确定机器人组中领导者的机制,建立了有领导者的机器人组的协作方法。其中,领导者与监控平台之间采用无线通讯,机器人组内采用CAN(control area network)总线传递控制信号。同时采用组内基于状态表匹配的控制方式。两个机器人组合利用以上机制,通过相互协调完成差速转弯的实验验证了该控制方法的可行性。