126 resultados para 477


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研究了樟脑磺酸掺杂的聚苯胺 (PAn CSA)膜的导电性对温度的依赖性 ,发现有一个临界温度 (Tc) ,当测试温度高于Tc 时 ,PAn CSA显示金属的导电特性 ,反之则显示半导体导电特性 .Tc 和聚苯胺的分子量有关 ,分子量越高 ,Tc 越低 .单向拉伸后 ,PAn CSA膜的电导率大大提高 ,拉伸 6 0 %时 ,室温电导率可达 75 0S/cm ,但Tc 不随拉伸而变化

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D-半乳糖的测定多使用酶法,近年来用酶电极测定血液中的半乳糖含量的方法已有报道[l-3],这些酶电极都有良好的重现性和很短的响应时间,缺点是测定时干扰严重,选择性差.

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By doping Sb, Ba and In to the Bi-system and with the variation of nominal atomic ratio of Cu, Sr and Ca, a new possible phase is found with T(c) almost-equal-to 105 K, but with a structure of 2212 phase. Effects of post-sintering treatment from air-quenched to O2-annealed were investigated for the approximately 105 K new phase.

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受激粒子之间由于碰撞而发生能量转移的现象时有发生。在几种类型的荧光谱线中,除了共振荧光和直跃线荧光中的粒子来源于激发

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A pattern recognition protein (PRP), lipopolysaccharide and beta-1,3-glucan binding protein (LGBP) cDNA was cloned from the haemocyte of Chinese shrimp Fenneropenaeus chinensis by the techniques of homology cloning and RACE. Analysis of nucleotide sequence revealed that the full-length cDNA of 1,275 bp has an open reading frame of 1,098 bp encoding a protein of 366 amino acids including a 17 amino acid signal peptide. Sequence comparison of the deduced amino acid sequence of F. chinensis LGBP showed a high identity of 94%, 90%, 87%, 72% and 63% with Penaeus monodon BGBP, Litopenaeus stylirostris LGBP, Marsupenaeu japonicus BGBP, Homarus gammarus BGBP and Pacifastacus leniusculus LGBP, respectively. The calculated molecular mass of the mature protein is 39,857 Da with a deduced pI of 4.39. Two putative integrin binding motifs, RGD (Arg-Gly-Asp) and a potential recognition motif for beta-1,3-linkage of polysaccharides were observed in LGBP sequence. RT-PCR analysis showed that LGBP gene expresses in haemocyte and hepatopancreas only, but not in other tissues. Capillary electrophoresis RT-PCR method was used to quantify the variation of mRNA transcription level during artificial infection with heat-killed Vibrio anguillarum and Staphylococcus aureusin. A significant enhancement of LGBP transcription was appeared at 6 h post-injection in response to bacterial infection. These results have provided useful information to understand the function of LGBP in shrimp.

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ISG15 is an interferon-stimulated gene that encodes a ubiquitin-like protein. ISG15 homologues have been identified in a number of fish species, some of which are known to be regulated at expression level by virus infection and lipopolysacchande (LPS) treatment However, the relationship between ISG15 and live bacterial infection has not been investigated in piscine models. In this study, an ISG15 homologue, SoISG15, was identified from red drum Scraeriops ocellaws and analyzed at expression and functional levels The open reading frame ofSolSG15 is 477 base pairs (bp) and mtronless, with a 5'-untranslated region (UTR) of 91 bp and a 3'-UTR of 415 bp The deduced amino acid sequence of S0ISG15 shares 60-67% overall identities with the ISG15 of several fish species. S0ISG15 possesses two conserved ubiquinn-like domains and the canonical ubiquitin conjugation motif, LRGG, at the C-terminus. Expressional analysis showed that constitutive expression of SolSG15 was highest in blood and lowest in kidney Experimental challenges with LPS and bacterial pathogens induced significant S0ISG15 expression in the kidney but not in the liver Similar differential induction was also observed at cellular level with primary hepatocytes and head kidney (HK) lymphocytes. Poly(' C), however, effected drastic induction of S0ISG15 expression in kidney and liver at both tissue and cellular levels. Immunoblot analysis showed that S0ISG15 was secreted by cultured HK lymphocytes into the extracellular milieu. Recombinant S0ISG15 expressed in and purified from Eschenclua colt was able to enhance the respiratory burst activity, acid phosphatase activity, and bactericidal activity of HK macrophages. Taken together, the results of this study indicated that SoISG 15 possesses apparent immunological property and is likely to be involved in host immune defense against bacterial infection. (C)2010 Elsevier Ltd All rights reserved.

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对虾病害在世界范围内肆虐,给水产养殖和沿海农村经济造成了重大损失。在水产养殖的实践中快速检测水产动物的病害并及时采取隔离等措施对于控制病害尤为重要,其中关键的环节就是快速检测出病害,并在对虾免疫机制上寻找对虾疾病防治的有效方法。研究表明当对虾等甲壳动物受到外界病原刺激时,极微量的微生物多糖就可以激活proPO系统。激活过程中涉及和产生一系列活性物质,如黑色素、酚氧化酶原激活因子(PPA)、模式识别蛋白(BGBP、PGBP、LGBP、LBP)及其膜上受体和A2巨球蛋白等,它们可通过多种方式参与防御反应,包括提供调理素,促进血细胞吞噬作用,形成结节或包囊以及介导凝集和凝固,产生杀菌物质并且黑色素化。黑色素常常在节肢动物的体表形成黑色斑点,形成的色素沉着对机体起到保护作用。所以,酚氧化酶原激活的级联反应是节肢动物免疫的关键因素。本论文研究开发了以环等温介导技术(LAMP)为基础的检测对虾白斑病毒(WSSV)和鳗弧菌(V. anguillarum)的快速检测方法。并从对虾对病害的免疫机制为切入点,从中国明对虾体内克隆了酚氧化酶原(PrpPO)和丝氨酸蛋白酶FcSP3这两个免疫系统中重要的基因,分析了它们的分子结构特征,组织分布及应答鳗弧菌病原刺激的表达变化模式。 建立的对虾常见病害对虾白班病毒(WSSV)和鳗弧菌(V. anguillarum)的LAMP检测方法,经过实验比对和Blast检索,发现本研究中使用的引物,比已经报导的LAMP方法或者PCR方法具有更宽的检测范围(更低的假阴性)。检测WSSV的LAMP方法使用病毒的VP28基因设计引物,而鳗弧菌的检测方法使用empA基因设计引物。在方法中,首次提出加入UNG酶和dUTP的措施来预防污染,在实际检测中非常有效。LAMP方法与PCR检测方法的灵敏性比较也进行了研究,二者灵敏性相当。 依据中国明对虾血液cDNA文库提供的部分片段信息,结合SMART-RACE技术,克隆了酚氧化酶原(PrpPO)基因,通过序列比对分析发现,PrpPO基因cDNA全长为3040 bp,其中开放阅读框2061 bp,编码686个氨基酸,其中推测的信号肽为12个氨基酸。推测的序列与斑节对虾(P. monodon)同源性为93%,与短钩对虾(P. semisulcatus.)同源性为92%。real time RT-PCR实验结果表明, ProPO在血细胞中的相对表达量最高,肝胰脏中表达量最低。弧菌刺激实验中注射弧菌,刺激了血细胞和淋巴器官中的ProPO mRNA显著增加,说明在血细胞和淋巴器官中存在快速反应的ProPO通路。而ProPO mRNA量在淋巴器官中在时间上早于血液中升至最高,说明该动物在在病原刚开始入侵的时候先有淋巴器官发挥主要的免疫作用,随着时间推移血细胞便变成主要的免疫器官。 根据中国明对虾肝胰脏cDNA文库提供EST信息,经过SMART-RACE克隆了一个丝氨酸蛋白酶FcSP3基因,通过序列比对分析发现,该丝氨酸蛋白酶基因cDNA全长为1622 bp,其中开放阅读框1431 bp,编码477个氨基酸,其中推测的信号肽为22个氨基酸。推测的序列与疟蚊的丝氨酸蛋白酶(A. gambiae)同源性为33%,与丽蝇蛹集金小蜂的酚氧化酶原激活因子(N. vitripennis)同源性为32%,与东北大黑鳃金龟的酚氧化酶原激活因子(H. diomphalia)同源性为34%。淋巴器官中PPAⅡ表达量约为血液中表达量的47560倍,肝胰脏中的FCSP3表达量为血细胞表达量的6226倍。鳗弧菌注射对虾后,淋巴器官中刺激组和对照组FcSP3的mRNA量在刺激后6小时显著降低,但是刺激组的表达量明显高于对照组。刺激组的血细胞与肝胰脏中FcSP3 mRNA的相对表达量增高。而病原刺激后的血液与肝胰脏中的FcSP3 mRNA的增长趋势也在时间上先与ProPO mRNA。这说明FcSP3对ProPO有正调控的作用,但这个调控有一个时间差,并且在不同组织中有不同的调控效率。

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Duplications and rearrangements of coding genes are major themes in the evolution of mitochondrial genomes, bearing important consequences in the function of mitochondria and the fitness of organisms. Yu et al. (BMC Genomics 2008, 9: 477) reported the complete mt genome sequence of the oyster Crassostrea hongkongensis (16,475 bp) and found that a DNA segment containing four tRNA genes (trnK(1), trnC, trnQ(1) and trnN), a duplicated (rrnS) and a split rRNA gene (rrnL5') was absent compared with that of two other Crassostrea species. It was suggested that the absence was a novel case of "tandem duplication-random loss" with evolutionary significance. We independently sequenced the complete mt genome of three C. hongkongensis individuals, all of which were 18,622 bp and contained the segment that was missing in Yu et al.'s sequence. Further, we designed primers, verified sequences and demonstrated that the sequence loss in Yu et al.'s study was an artifact caused by placing primers in a duplicated region. The duplication and split of ribosomal RNA genes are unique for Crassostrea oysters and not lost in C. hongkongensis. Our study highlights the need for caution when amplifying and sequencing through duplicated regions of the genome.

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Sulfanilamide derivatives of chitosan (2-(4-acetamido-2-sulfanimide)-chitosan (HSACS, LSACS), 2-(4-acetamido-2-sulfanimide)-6-sulfo-chitosan (HSACSS, LSACSS) and 2-(4-acetamido-2-sulfanimide)-6-carboxymethyl-chitosan (HSACMCS, LSACMCS)) were prepared using different molecular weights of chitosan (CS), carboxymethyl chitosan (CMCS) and chitosan sulfates (CSS) reacted with 4-acetamidobenzene sulfonyl chloride in dimethylsulfoxide solution. The structures of the derivatives were characterized by FT-IR spectroscopy and elemental analysis, which showed that the substitution degree of sulfanilamide group of HSACS, HSACSS, HSACMCS, LSACS, LSACSS and LSACMCS were 0.623, 0.492, 0.515, 0.576, 0.463 and 0.477, respectively. The solubility of the derivatives (pH < 7.5) was higher than that of chitosan (pH < 6.5). The antifungal activities of the derivatives against Aiternaria solani and Phomopsis asparagi were evaluated based on the method of Jasso et al. in the experiment. The results indicated that all the prepared sulfanilamide derivatives had a significant inhibiting effect on the investigated fungi in the polymer concentration range from 50 to 500 mu g mL(-1). The antifungal activities of the derivatives increased with increasing the molecular weight, concentration or the substitution degree. The sulfanilamide derivatives of CS, CMCS and CSS show stronger antifungal activities than CS, CMCS and CSS. (C) 2007 Elsevier Ltd. All rights reserved.

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依据祁连山海北高寒湿地植物生长期观测资料, 分析了区域辐射收支情况及其变化特征. 结果表明: 祁连山海北高寒湿地有较强的太阳总辐射(DR), 但地表反射辐射(UR)、地面有效辐射(ELR)较低;地表长波辐射(ULR)、大气逆辐射(DLR)、净辐射(Rn)均较高, 且具有明显的日、季节变化. 植物生长期5~9月的日变化振幅DR>Rn>UR>ULR>DLR>ELR, 其总量表现出ULR>DLR>DR>Rn>UR>ELR, 分别达4650.6、 4225.5、 3058.8、 2156.2、 477.6和425.1 MJ•m-2. 从月际分布来看, ULR、 DLR、 DR最高出现在7月, Rn出现在6月, UR出现在5月, ELR出现在8月, 分别为980.3、 913.1、 721.5、 554.9、 112.1和127.4 MJ•m-2.

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通过交叉抚育建立室内繁殖种群,在断奶后(80日龄)分别取这些供体的新鲜尿气味作刺激物,在行为观察箱中观察和记录雄性根田鼠对雌鼠气味的行为反应,以研究根田鼠同胞识别的化学通讯机制.结果表明:①在不同的发育时期(2~70日龄),雄性同巢同胞与异巢同胞的体重没有显著差异.②雄性根田鼠对雌性同巢非同胞气味的接近潜伏期显著长于对异巢非同胞的接近潜伏期(P<0.05),其对异巢非同胞气味的访问时间和嗅舔时间都显著高于同巢非同胞气味(P<0.05).③雄性根田鼠对雌性异巢同胞和异巢非同胞气味的不存在明显偏好.其对两者的接近潜伏期、访问频次、访问时间、嗅舔频次和嗅舔时间等行为响应均无显著差异(P<0.05).这些结果表明,80日龄时,雄性根田鼠能够识别熟悉和陌生的无亲属关系雌性尿气味,但不能区分陌生的亲属和非亲属,因此,其异性同胞识别的机制为共生熟悉模式.`

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Rhubarb is an important Traditional Chinese Medicine. However, the wild resource has been declining. In order to design appropriate conservation methods for the official species across their natural distributions, it is important to characterize their genetic diversity. Here, we describe the development of 10 new microsatellite loci for AC/TG/CCA in Rheum tanguticum. The microsatellites were enriched using the combined biotin capture method. The polymorphism of each locus was further assessed in 12 individuals from four geographically distinct populations of this species. The number of alleles ranged from three to seven and the expected heterozygosity ranged from 0.53 to 0.73. All markers have been checked in the other three species in the genus and two of them together comprise the official medicinal rhubarb resource, with R. tanguticum. These microsatellite markers could. provide a useful tool for genetic and conservation studies of the rhubarb species.

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Reported are the results of the Latin American Collaborative Study of Congenital Malformations (ECLAMC), a hospital-based case-control study of 34 293 malformed and 34 477 matched nonmalformed newborn controls. No statistical differences were found between the malformed and control groups, exposed or not exposed to tetanus toroid.

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菌根是真菌与植物根组织形成的共生联合体.具有形成菌根能力的真菌,叫做菌根真菌.根据真菌菌丝体在菌根组织内的形态结构,菌根主要分为外生菌根、内生菌根和内外生菌根三种类型.

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在总结云南白马寨镍矿区煌斑岩成因信息的基础上,利用岩石学混合计算方法对其地幔源区成分进行了模拟,进而讨论矿区这类岩石的成因。地球化学和模拟计算均表明,白马寨镍矿区煌斑岩来源于交代富集地幔,板块俯冲(印度板块向欧亚板块俯冲)过程中富含ALK、LREE及不相容元素的海底沉积物被带入地幔脱水形成的流体是引起本区地幔交代作用的主要因素.