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971.
The 70% aq methanolic extract of the Peruvian plant Stylogne cauliflora was found to contain two novel oligophenolic compounds SCH 644343 (1) and SCH 644342 (2), which were identified as inhibitors of HCV NS3 protease. The structure of 1 and 2 was established based on high-resolution NMR studies. Compound 1 inhibited HCV NS3 protease with an IC(50) of 0.3 microM, while compound 2 showed an IC(50) of 0.8 microM.  相似文献   
972.
本文采用EBV(Epstein?Barr Virus)上清液转化B淋巴细胞,并加入环胞霉素A(Cyclosporine A)抑制T淋巴细胞,成功地对中国东北地区鄂温克族、鄂伦春族及达斡尔族的部分个体建立了永生细胞系,其中鄂温克族49株,鄂伦春族40株,达斡尔族51株,总计140株。永久保存我国特有民族的基因组,为分析其遗传学差异奠定了基础。 Abstract:The immortal lymphoblastoid cell lines were established by EBV transformation of B cells and addition of cyclosporin A to inhabit the activity of T cells.In the present study ,140 immortal cell lines of the Ewenki,the Oroqen and the Daur ethnic groups in the Northeast China were established .This is an important part of the research of human genome diversity for the exploration of the origin and progression of different ethnic groups ,and also provide enough research materials for further studies.  相似文献   
973.
Abstract: Two fatty acid binding proteins (FABPs) were isolated from Swiss Webster mouse brains. Neither protein cross-reacted with antisera to recombinant liver L-FABP. One protein, designated brain H-FABP, migrated on tricine sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) as a single band at 14.5 kDa with pl 4.9. Brain H-FABP bound NBD-stearic acid and cis -parinaric acid with K D values near 0.02 and 0.5 µ M , respectively. Brain H-FABP cross-reacted with affinity-purified antisera to recombinant heart H-FABP. The second protein, mouse brain B-FABP, migrated on tricine SDS-PAGE gels as a doublet at 16.0 and 15.5 kDa with pl values of 4.5 and 4.7, respectively. Brain B-FABP bound NBD-stearic acid and cis -parinaric acid with K D values near 0.01 and 0.7 µ M , respectively. The brain B-FABP doublet was immunoreactive with affinity-purified antibodies against recombinant mouse brain B-FABP, but not with affinity-purified antibodies against heart H-FABP. [3H]Oleate competition binding indicated that the two brain FABPs had distinct ligand binding specificities. Both bound fatty acids, fatty acyl CoA, and lysophosphatidic acid. Although both preferentially bound unsaturated fatty acids, twofold differences in specific saturated fatty acid binding were observed. Brain B-FABP and brain H-FABP represented 0.1 and 0.01% of brain total cytosolic protein, respectively. In summary, mouse brain contains two native fatty acid binding proteins, brain H-FABP and brain B-FABP.  相似文献   
974.
Developing high‐voltage Mg‐compatible electrolytes (>3.0 V vs Mg) still remains to be the biggest R&D challenge in the area of nonaqueous rechargeable Mg batteries. Here, the key design concepts toward exploring new boron‐based Mg salts in a specific way of highlighting the implications of anions are proposed for the first time. The well‐defined boron‐centered anion‐based magnesium electrolyte (BCM electrolyte) is successfully presented by facile one‐step mixing of tris(2H‐hexafluoroisopropyl) borate and MgF2 in 1,2‐dimethoxyethane, in which the structures of anions have been thoroughly investigated via mass spectrometry accompanied by NMR and Raman spectra. The first all‐round practical BCM electrolyte fulfills all requirements of easy synthesis, high ionic conductivity, wide potential window (3.5 V vs Mg), compatibility with electrophilic sulfur, and simultaneously noncorrosivity to coin cell assemblies. When utilizing the BCM electrolyte, the fast‐kinetics selenium/carbon (Se/C) cathode achieves the best rate capability and the sulfur/carbon (S/C) cathode exhibits an impressive prolonged cycle life than previously published reports. The BCM electrolyte offers the most promising avenue to eliminate the major roadblocks on the way to high‐voltage Mg batteries and the design concepts can shed light on future exploration directions toward high‐voltage Mg‐compatible electrolytes.  相似文献   
975.
微波提取天仙果多糖的工艺研究   总被引:7,自引:0,他引:7  
本文通过对影响天仙果多糖提取的因素进行工艺研究 ,初步确认微波提取天仙果多糖宜在 80℃的碱性介质中结合微波前处理可获较高提取率。通过大孔树脂纯化 ,以及纸层析和硅胶G薄板层析分析表明 ,碱性介质中微波提取的天仙果多糖是复合多糖 ,可能由三个均一多糖组分组成。  相似文献   
976.
Escherichia coli asparagine synthetase B (AS-B) catalyzes the formation of asparagine from aspartate in an ATP-dependent reaction for which glutamine is the in vivo nitrogen source. In an effort to reconcile several different kinetic models that have been proposed for glutamine-dependent asparagine synthetases, we have used numerical methods to investigate the kinetic mechanism of AS-B. Our simulations demonstrate that literature proposals cannot reproduce the glutamine dependence of the glutamate/asparagine stoichiometry observed for AS-B, and we have therefore developed a new kinetic model that describes the behavior of AS-B more completely. The key difference between this new model and the literature proposals is the inclusion of an E.ATP.Asp.Gln quaternary complex that can either proceed to form asparagine or release ammonia through nonproductive glutamine hydrolysis. The implication of this model is that the two active sites in AS-B become coordinated only after formation of a beta-aspartyl-AMP intermediate in the synthetase site of the enzyme. The coupling of glutaminase and synthetase activities in AS is therefore different from that observed in all other well-characterized glutamine-dependent amidotransferases.  相似文献   
977.
羊蹄甲属中国特有种的花粉形态学   总被引:1,自引:0,他引:1  
对羊蹄甲属植物11种中国特有种的花粉形态进行了研究。结果表明,花粉萌发孔类型均为三孔沟,少数还有合沟;花粉均具半覆盖层,表面纹饰有皱波状、皱波状-穿孔、疣状、孔穴-穿孔、穿孔-网状。依据Larsen(1975)的划分,这11种植物的花粉隶属于Integrifolia型、Glauca型和Curtisii型,我们根据花粉纹饰的差异在Integrifolia型下进一步划分了Auma亚型和Paucinervata亚型。  相似文献   
978.
Figaro: a novel statistical method for vector sequence removal   总被引:1,自引:0,他引:1  
MOTIVATION: Sequences produced by automated Sanger sequencing machines frequently contain fragments of the cloning vector on their ends. Software tools currently available for identifying and removing the vector sequence require knowledge of the vector sequence, specific splice sites and any adapter sequences used in the experiment-information often omitted from public databases. Furthermore, the clipping coordinates themselves are missing or incorrectly reported. As an example, within the approximately 1.24 billion shotgun sequences deposited in the NCBI Trace Archive, as many as approximately 735 million (approximately 60%) lack vector clipping information. Correct clipping information is essential to scientists attempting to validate, improve and even finish the increasingly large number of genomes released at a 'draft' quality level. RESULTS: We present here Figaro, a novel software tool for identifying and removing the vector from raw sequence data without prior knowledge of the vector sequence. The vector sequence is automatically inferred by analyzing the frequency of occurrence of short oligo-nucleotides using Poisson statistics. We show that Figaro achieves 99.98% sensitivity when tested on approximately 1.5 million shotgun reads from Drosophila pseudoobscura. We further explore the impact of accurate vector trimming on the quality of whole-genome assemblies by re-assembling two bacterial genomes from shotgun sequences deposited in the Trace Archive. Designed as a module in large computational pipelines, Figaro is fast, lightweight and flexible. AVAILABILITY: Figaro is released under an open-source license through the AMOS package (http://amos.sourceforge.net/Figaro).  相似文献   
979.
DREP-1基因在果蝇的细胞凋亡过程中对DNA的降解有重要调控作用.本研究将该基因序列在家蚕EST数据库中进行同源性检索,把检索到的EST序列进行电子延伸和克隆重叠群拼接,根据拼接结果设计引物进行PCR扩增并克隆测序验证,首次成功克隆了家蚕第一个ICAD基因BmICAD的cDNA:该cDNA全长844 bp,ORF长522 bp,编码含有174个氨基酸的蛋白;预测分子量为19 6 kDa,等电点为4.23,所编码蛋白与果蝇DREP-1的一致性(identity)为36%;虽然Northern印记杂交未检测到信号,但是RT-PCR结果显示,该基因在精巢中特异表达.  相似文献   
980.
Intraperitoneal injection of CCK reduces food intake and triggers a behavioral pattern similar to natural satiation. Reduction of food intake by CCK is mediated by vagal afferents that innervate the stomach and small intestine. These afferents synapse in the hindbrain nucleus of the solitary tract (NTS) where gastrointestinal satiation signals are processed. Previously, we demonstrated that intraperitoneal (IP) administration of either competitive or noncompetitive N-methyl-d-aspartate (NMDA) receptor antagonists attenuates reduction of food intake by CCK. However, because vagal afferents themselves express NMDA receptors at both central and peripheral endings, our results did not speak to the question of whether NMDA receptors in the brain play an essential role in reduction of feeding by CCK. We hypothesized that activation of NMDA receptors in the NTS is necessary for reduction of food intake by CCK. To test this hypothesis, we measured food intake following IP CCK, subsequent to NMDA receptor antagonist injections into the fourth ventricle, directly into the NTS or subcutaneously. We found that either fourth-ventricle or NTS injection of the noncompetitive NMDA receptor antagonist MK-801 was sufficient to inhibit CCK-induced reduction of feeding, while the same antagonist doses injected subcutaneously did not. Similarly fourth ventricle injection of d-3-(2-carboxypiperazin-4-yl)-1-propenyl-1-phosphoric acid (d-CPPene), a competitive NMDA receptor antagonist, also blocked reduction of food intake following IP CCK. Finally, d-CPPene injected into the fourth ventricle attenuated CCK-induced expression of nuclear c-Fos immunoreactivity in the dorsal vagal complex. We conclude that activation of NMDA receptors in the hindbrain is necessary for the reduction of food intake by CCK. Hindbrain NMDA receptors could comprise a critical avenue for control and modulation of satiation signals to influence food intake and energy balance.  相似文献   
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