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排序方式: 共有628条查询结果,搜索用时 31 毫秒
91.
REN Yuanyuan DAI Xiuyu ZHOU Jian LIU Jingfang PEI Huadong & XIANG Hua . State Key Laboratory of Microbial Resources Center for Molecular Microbiology Institute of Microbiology Chinese Academy of Sciences Beijing China . Graduate School of Chinese Academy of Sciences Beijing China 《中国科学:生命科学英文版》2005,48(3):221-227
Trehalose is a non-reducing disaccharide of glucosewidely distributed in microorganisms, plants and in-sects. It usually functions as a compatible solute in thestabilization of biological structures under several en-vironment stresses[1,2]. Trehalose has proved to be anactive stabilizer of enzymes, proteins, biomasses, pharmaceutical preparations and even organs fortransplantation. Thus much attention has been paid tothe synthesis pathway of trehalose and the develop-ment of novel and economic… 相似文献
92.
应用了以硒化镉量子点为荧光探针,具有磁性和抗体双重靶向功能的聚苯乙烯磁微球.设计了基于此种磁微球的新型微悬臂梁式免疫传感器,满足在液相环境中,借助嵌入到聚苯乙烯磁微球的荧光探针及微球表面的特异性抗体探针,达到生物分子的定性检测,借助具有纳米机械响应的微悬臂梁及微平面电感线圈,达到生物分子的定量检测及传感器的复用性,解决传统微悬臂梁式免疫传感器的不足.着重对三种粒径尺寸的硒化镉量子点进行了表征,同时针对片上磁分离的机理,梁上微电感线圈的结构,微磁场对磁微球的吸引进行了研究,设计并优化出满足新型微悬臂梁式免疫传感器所需的蛇形微平面电感线圈.通过生物磁分离实验,验证了设计及优化的结果,实现了用于生物分子分离的片上磁分离技术. 相似文献
93.
Chemopreventive potential of Acacia nilotica bark extract (ANBE) against single intraperitoneal injection of N-nitrosodiethylamine (NDEA, 200 mg/kg) followed by weekly subcutaneous injections of carbon tetrachloride (CCl4, 3 ml/kg) for 6 weeks induced hepatocellular carcinoma (HCC) in rats was studied. At 45 day after administration of NDEA, 100 and 200 mg/kg of ANBE were administered orally once daily for 10 weeks. The levels of liver injury and liver cancer markers such as alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), γ-glutamyl transferase (γ-GT), total bilirubin level (TBL), α-feto protein (AFP) and carcinoembryonic antigen (CEA) were substantially increased following NDEA treatment. However, ANBE treatment reduced liver injury and restored liver cancer markers. ANBE also significantly prevented hepatic malondialdehyde (MDA) formation and reduced glutathione (GSH) in NDEA-treated rats which was dose dependent. Additionally, ANBE also increased the activities of antioxidant enzymes viz., catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione-S-transferase (GST) in the liver of NDEA-administered rats. Eventually, ANBE also significantly improved body weight and prevented increase of relative liver weight due to NDEA treatment. Histological observations of liver tissues too correlated with the biochemical observations. HPLC analysis of ANBE showed the presence of gallic, protocatechuic, caffeic and ellagic acids, and also quercetin in ANBE. The results strongly support that A. nilotica bark prevents lipid peroxidation (LPO) and promote the enzymatic and non-enzymatic antioxidant defense system during NDEA-induced hepatocarcinogenesis which might be due to activities like scavenging of oxy radicals by the phytomolecules in ANBE. 相似文献
94.
Hlavica P 《Biotechnology advances》2009,27(2):103-121
The high plasticity of the active-site cavity of cytochromes P450, permitting reactivity toward a vast array of compounds, makes these enzymes attractive targets for biotechnological application. Escalating attention in this area is driven by remarkable progress in the rational design by DNA shuffling of self-sufficient, multi-domain P450/electron donor constructs simplifying the composition of biocatalytic systems. Moreover, versatile approaches were undertaken to supersede the well-established, NAD(P)H-steered proteinaceous redox chains by cost-effective alternative electron transfer conduits constituted of organometallic mediators or photoactivatable redox triggers. Electrochemical techniques have proven particularly useful: employing different types of carbon- and metal-based electrodes for the fabrication of biosensors, the continuing challenge was to optimize the conductive properties of these devices by creating biocompatible interfaces for transferring electrons between sensor surfaces and redox proteins. The present review provides a critical update of the most significant breakthroughs in innovative manipulation of the redox machinery, giving an impulse to exploitation of P450s in fields such as the production of fine chemicals, drug processing, medicinal diagnostics and remediation of biotopes contaminated with harmful environmental pollutants. 相似文献
95.
Mesoderm migration is a well studied morphogenetic movement that takes place during Xenopus gastrulation. The study of mesoderm migration and other morphogenetic movements has been primarily based on in vitro assays due to the inability to image deep tissue movements in the opaque embryo. We are the first to report the use of Near Infra Red Quantum Dots (NIR QD’s) to image mesoderm migration in vivo with single cell resolution and provide quantitative in vivo data regarding migration rates. In addition we use QD’s to address the function of the focal adhesion kinase (FAK) in this movement. Inhibition of FAK blocks mesoderm spreading and migration both in vitro and in vivo without affecting convergent extension highlighting the molecular differences between the two movements. These results provide new insights about the role of FAK and of focal adhesions during gastrulation and provide a new tool for the study of morphogenesis in vivo. 相似文献
96.
Eduardo Gusmão Pereira Marco Antonio Oliva Kacilda Naomi Kuki José Cambraia 《Trees - Structure and Function》2009,23(2):277-285
The effect of iron solid particulate matter (SPMFe) deposited onto soil and leaves on photosynthesis and oxidative stress was evaluated in Clusia hilariana, a CAM tropical tree of high occurrence in Brazilian restingas. Significant increases in iron content were found in plants
exposed to SPMFe applied onto leaf and soil surfaces. However, only the application of SPMFe on leaves of C. hilariana caused significant reductions in some evaluated characteristics such as photosynthetic rate, stomatal conductance, transpiration,
organic acid accumulation, potential quantum yield of PSII, and changes in daily CAM photosynthesis pattern. Increase in relative
membrane permeability and reduction in catalase and superoxide dismutase activities in the leaves of plants exposed to SPMFe also were observed; however, lipid peroxidation did not change. These responses seem to be due to the combination of physical
effects such as increase of leaf temperature, reduction in light absorption, obstruction of stomatal pores, and biochemical
effects triggered by oxidative stress. 相似文献
97.
Diffusive Movement of Processive Kinesin-1 on Microtubules 总被引:1,自引:0,他引:1
Hailong Lu M. Yusuf Ali Carol S. Bookwalter David M. Warshaw Kathleen M. Trybus 《Traffic (Copenhagen, Denmark)》2009,10(10):1429-1438
The processive motor kinesin-1 moves unidirectionally toward the plus end of microtubules. This process can be visualized by total internal reflection fluorescence microscopy of kinesin bound to a carboxylated quantum dot (Qdot), which acts both as cargo and label. Surprisingly, when kinesin is bound to an anti-HIS Qdot, it shows diffusive movement on microtubules, which decreased in favor of processive runs with increasing salt concentration. This observation implies that kinesin movement on microtubules is governed by its conformation, as it is well established that kinesin undergoes a salt-dependent transition from a folded (inactive) to an extended (active) molecule. A truncated kinesin lacking the last 75 amino acids (kinesin-ΔC) showed both processive and diffusive movement on microtubules. The extent of each behavior depends on the relative amounts of ADP and ATP, with purely diffusive movement occurring in ADP alone. Taken together, these data imply that folded kinesin.ADP can exist in a state that diffuses along the microtubule lattice without expending energy. This mechanism may facilitate the ability of kinesin to pick up cargo, and/or allow the kinesin/cargo complex to stay bound after encountering obstacles. 相似文献
98.
Michael Wormit 《BBA》2009,1787(6):738-9506
Light harvesting complexes have been identified in all chlorophyll-based photosynthetic organisms. Their major function is the absorption of light and its transport to the reaction centers, however, they are also involved in excess energy quenching, the so-called non-photochemical quenching (NPQ). In particular, electron transfer and the resulting formation of carotenoid radical cations have recently been discovered to play an important role during NPQ in green plants. Here, the results of our theoretical investigations of carotenoid radical cation formation in the major light harvesting complex LHC-II of green plants are reported. The carotenoids violaxanthin, zeaxanthin and lutein are considered as potential quenchers. In agreement with experimental results, it is shown that zeaxanthin cannot quench isolated LHC-II complexes. Furthermore, subtle structural differences in the two lutein binding pockets lead to substantial differences in the excited state properties of the two luteins. In addition, the formation mechanism of carotenoid radical cations in light harvesting complexes LH2 and LH1 of purple bacteria is studied. Here, the energetic position of the S1 state of the involved carotenoids neurosporene, spheroidene, spheroidenone and spirilloxanthin seems to determine the occurrence of radical cations in these LHCs upon photo-excitation. An elaborate pump-deplete-probe experiment is suggested to challenge the proposed mechanism. 相似文献
99.
Mike Friedrich Revaz Nozadze Qiang Gan Vladimir Ermolayev Gregory S. Harms 《Biochemical and biophysical research communications》2009,390(3):722-8
Single-molecule detection and tracking is important for observing biomolecule interactions in the microenvironment. Here we report selective plane illumination microscopy (SPIM) with single-molecule detection in living organisms, which enables fast imaging and single-molecule tracking and optical penetration beyond 300 μm. We detected single nanocrystals in Drosophila larvae and zebrafish embryo. We also report our first tracking of single quantum dots during zebrafish development, which displays a transition from flow to confined motion prior to the blastula stage. The new SPIM setup represents a new technique, which enables fast single-molecule imaging and tracking in living systems. 相似文献
100.
Diego Rojas-Rivera Valentina Parra Ariel Contreras Mario Chiong Claudio Olea-Azar 《FEBS letters》2009,583(21):3485-3492
We investigated the role of Ca2+ in generating reactive oxygen species (ROS) induced by hyposmotic stress (Hypo) and its relationship to regulatory volume decrease (RVD) in cardiomyocytes. Hypo-induced increases in cytoplasmic and mitochondrial Ca2+. Nifedipine (Nife) inhibited both Hypo-induced Ca2+ and ROS increases. Overexpression of catalase (CAT) induced RVD and a decrease in Hypo-induced blebs. Nife prevented CAT-dependent RVD activation. These results show a dual role of Hypo-induced Ca2+ influx in the control of cardiomyocyte viability. Hypo-induced an intracellular Ca2+ increase which activated RVD and inhibited necrotic blebbing thus favoring cell survival, while simultaneously increasing ROS generation, which in turn inhibited RVD and induced necrosis. 相似文献