731 resultados para 831
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The pacifastin family, characterized by several conserved arrays of six cysteine residues, is a newly identified serine protease inhibitor (SPI) family discovered uniquely in arthropods and plays important roles in multiple biological processes. In the present study, the full-length cDNA of a pacifastin light chain (designated ESPLC) was cloned from the Chinese mitten crab Eriocheir sinensis by expressed sequence tags (ESTs) and PCR techniques. The 1036 bp ESPLC cDNA contained an 831 bp open reading frame (ORF) encoding a putative pacifastin-related peptide of 276 amino acids, a 5'-untranslated region (UTR) of 67 bp, and a 3'-UTR of 138 bp. Six putative conserved domains sharing a characteristic cysteine array (Cys-Xaa(9-12)-Cys-Asn-Xaa-Cys-Xaa-Cys-Xaa(2-3)-Gly-Xaa(3-4)-Cys-Thr-Xaa(3)-Cys) were identified in the deduced amino acid sequence of ESPLC. The conservation of these PLDs (pacifastin light chain domains) and the relative higher similarity of ESPLC to other pacifastin-related precursors suggested that ESPLC was a member of pacifastin family. The mRNA transcripts of ESPLC were found to be higher expressed in hepatopancreas, gill and haemolymph than in gonad, muscle and heart, with the highest expression level in hepatopancreas. The ESPLC mRNA expression in haemolymph of Chinese mitten crab was up-regulated at 2 h and 12 h after challenged with Listonella anguillarum. The tissue distribution and temporal characteristics of ESPLC mRNA expression, similar to that of prophenoloxidase gene in E. sinensis, suggested that ESPLC was potentially involved in the response against invading bacteria, with the possibility that it functioned in the prophenoloxidase system in E sinensis. (C) 2008 Elsevier Ltd. All rights reserved.
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Lipopolysaccharide and beta-1, 3-glucan binding protein (LGBP) is a kind of pattern recognition receptor, which can recognize and bind LPS and beta-1, 3-glucan, and plays curial roles in the innate immune defense against Gram-negative bacteria and fungi. In this study, the functions of LGBP from Zhikong scallop Chlamys farreri performed in innate immunity were analyzed. Firstly, the mRNA expression of CfLGBP in hemocytes toward three typical PAMPS stimulation was examined by realtime PCR. It was up-regulated extremely (P < 0.01) post stimulation of LPS and beta-glucan, and also exhibited a moderate up-regulation (P < 0.01) after PGN injection. Further PAMPs binding assay with the polyclonal antibody specific for CfLGBP proved that the recombinant CfLGBP (designated as rCfLGBP) could bind not only LPS and beta-glucan, but also PGN in vitro. More importantly, rCfLGBP exhibited obvious agglutination activity towards Gram-negative bacteria Escherichia coil, Gram-positive bacteria Bacillus subtilis and fungi Pichia pastoris. Taking the results of immunofluorescence assay into account, which displayed CfLGBP was expressed specifically in the immune cells (hemocytes) and vulnerable organ (gill and mantle), we believed that LGBP in C farreri, serving as a multi-functional PRR, not only involved in the immune response against Gram-negative and fungi as LGBP in other invertebrates, but also played significant role in the event of anti-Gram-positive bacteria infection. As the first functional research of LGBP in mollusks, our study provided new implication into the innate immune defense mechanisms of C. farreri and mollusks. (C) 2010 Elsevier Ltd. All rights reserved.
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本文在23 ℃和31.6S条件下系统地研究了六价铬离子对海弯扇贝Argopecten irradians胚胎和不同发育阶段的幼虫的影响。海弯扇贝胚胎,早期D形幼早(刚孵化出的平均壳长为91μm的D形幼虫)和壳顶幼早对Cr~(8+)的敏感性各不相同。Cr~(6+)对胚胎孵化45hr的半数影响浓度EC_(50)为2614.57μg/L;对早期D形幼虫和壳顶幼虫48hr的半致死浓度LC_(50)分别为4343.26和2323.27μg/L。因此,其敏感性大小依次为:壳顶幼早 > 胚胎 > D形幼虫。眼点的幼虫在变态的过程中对Cr~(6+)的反应尤为敏感,低浓度(<200μg/L)的Cr~(6+)对其变态则有很强的抑制作用,在831.19μg/L的Cr~(6+)作用下眼点幼虫的变态率仅为对照组的50%。Cr~(6+)对海湾贝D形幼虫的生长发育具有明显的抑制作用,随着Cr~(6+)浓度的升高,幼虫的生长速度逐渐减慢,死亡率逐渐升高,同一浓度的Cr~(6+)作用越长,毒性越大。Cr~(6+)对D形幼虫生长96hr和192hr的EC_(50)分别为1395.40和710.56μg/L。被Cr~(6+)污染的铒料(等鞭金藻Isochrysis galbana)亦可对海湾扇贝幼虫产生毒性影响,说明Cr~(6+)的性可通过铒料传递。AAS法分析表明Cr~(6+)在D形幼虫体内的累积随着外界Cr~(6+)浓度的升高而逐渐增多。根据海湾扇贝最敏感期--壳顶幼虫期对Cr~(6+)的起始反应浓度,建议在海湾扇贝人工育苗过程中水质控制Cr~(6+)浓度应低于14μg/L。
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首次报道了藏茵陈川西獐牙菜的大孢子发生及雌配子体发育。川西獐牙菜为倒生胚珠,薄珠心,单珠被,线形大孢子四分体,胚囊发育为蓼型,反足细胞分裂为5~8个,宿存,每个细胞均异常膨大,并多核。反足细胞在龙胆科一些一年生高山植物中的宿存和分裂具有重要的生殖适应和进化意义,这对于这些植物在青藏高原严酷的自然环境下,在短时间内完成其生活史是非常重要的。
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在开放(P_水
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Resumo dos resultados obtidos ao longo do ano de 2001, sobre o monitoramento das queimadas no Brasil, enviado para a campanha de controle e redução das queimadas na agricultura brasileira, realizada pelo Ministério da Agricultura, Pecuária e Abastecimento (MAPA). A campanha pretende estimular o uso de alternativas tecnológicas na agricultura que substituam as queimadas, em especial nas regiões Norte e Centro-Oeste, uma das áreas mais atingidas por essa prática. A dinâmica das queimadas revelou um crescimento significativo em 2001 com relação ao ano anterior e várias surpresas, tanto na sua repartição espacial, detalhadas neste trabalho.
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Fuel cell vehicles (FCVs) offer the potential of ultra-low emissions combined with high efficiency. Proton exchange membrane (PEM) fuel cells being developed for vehicles require hydrogen as a fuel. Due to the various pathways of hydrogen generation, both onboard and off-board, the question about which fuel option is the most competitive for fuel cell vehicles is of great current interest. In this paper, a life-cycle assessment (LCA) model was made to conduct a comprehensive study of the energy, environmental, and economic (3E) impacts of FCVs from well to wheel (WTW). In view of the special energy structure of China and the timeframe, 10 vehicle/fuel systems are chosen as the study projects. The results show that methanol is the most suitable fuel to serve as the ideal hydrogen source for fuel cell vehicles in the timeframe and geographic regions of this study. On the other hand, gasoline and pure hydrogen can also play a role in short-term and regional applications, especially for local demonstrations of FCV fleets. (c) 2004 Elsevier B.V All rights reserved.
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Jackson, Richard, Writing the War on Terrorism: Language, Politics and Counter-terrorism (Manchester: Manchester University Press, 2005), pp.viii + 232 RAE2008
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The development of ultra high speed (~20 Gsamples/s) analogue to digital converters (ADCs), and the delayed deployment of 40 Gbit/s transmission due to the economic downturn, has stimulated the investigation of digital signal processing (DSP) techniques for compensation of optical transmission impairments. In the future, DSP will offer an entire suite of tools to compensate for optical impairments and facilitate the use of advanced modulation formats. Chromatic dispersion is a very significant impairment for high speed optical transmission. This thesis investigates a novel electronic method of dispersion compensation which allows for cost-effective accurate detection of the amplitude and phase of the optical field into the radio frequency domain. The first electronic dispersion compensation (EDC) schemes accessed only the amplitude information using square law detection and achieved an increase in transmission distances. This thesis presents a method by using a frequency sensitive filter to estimate the phase of the received optical field and, in conjunction with the amplitude information, the entire field can be digitised using ADCs. This allows DSP technologies to take the next step in optical communications without requiring complex coherent detection. This is of particular of interest in metropolitan area networks. The full-field receiver investigated requires only an additional asymmetrical Mach-Zehnder interferometer and balanced photodiode to achieve a 50% increase in EDC reach compared to amplitude only detection.
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Es urgente tratar los contenidos matemáticos de forma que docentes y estudiantes sientan la necesidad de aprender matemáticas para poder dar solución a los múltiples problemas que a nivel mundial plantean servicios tales como salud, distribución, energía, conservación del agua, etc, así como la industria moderna; en calidad, competitividad y automatización. Corresponde a los matemáticos educativos demostrar que es necesario ampliar el horizonte teórico para dar solución a problemas complejos y hacer uso de modernas técnicas computacionales para realizar los cálculos. La idea es a partir de la necesidad, buscar el respaldo técnico y teórico que permitan cumplir el objetivo de dar solución al problema. De esta forma el objetivo del estudiante lo motiva a aprender.
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Book review of: Scarlett Thomas, PopCo, London and New York: Fourth Estate, 2004. 1-84115-763-5, £12.99.