排序方式: 共有61条查询结果,搜索用时 16 毫秒
41.
Joon Kim Dongho Lee Jinkyu Hong Sinkyu Kang Su-Jin Kim Sang-Ki Moon Jong-Hwan Lim Yowhan Son Jaeseok Lee Sanghyun Kim Namchil Woo Kyongha Kim Buyong Lee Byong-Lyol Lee Sung Kim 《Ecological Research》2006,21(6):881-889
The KoFlux program is dedicated to understanding the fluxes of energy and matter, water resource management, and net ecosystem
production in key ecosystems of Monsoon Asia. Under the framework of AsiaFlux, it is a joint effort with determined, comprehensive
international strategies to bring Asia’s key ecosystems under observation. Built upon the augmented KoFlux infrastructure
(i.e., Gwangneung supersite), the ‘HydroKorea’ and ‘CarboKorea’ projects pursue new methodologies to assess water and carbon
cycles at various temporal, spatial, and process scales. Particularly, the multiscaling approaches are used to link process-level
studies, flux footprint, ecohydrological and biogeochemical schemes, and high-resolution satellite images. We hope that the
work presented here encourages more ground-breaking studies aimed at bridging the gaps in the cross-scale studies of ecohydrological
and biogeochemical cycles in heterogeneous and complex landscapes. 相似文献
42.
It is becoming increasingly clear that characterization of the protein ensemble-the collection of all conformations of which the protein is capable-will be a critical step in developing a full understanding of the linkage between structure, dynamics, and function. X-ray solution scattering in the small angle (SAXS) and wide-angle (WAXS) regimes represents an important new window to exploring the behavior of ensembles. The characteristics of the ensemble express themselves in X-ray solution scattering data in predictable ways. Here we present an overview of the effect that structural diversity intrinsic to protein ensembles has on scattering data. We then demonstrate the observation of these effects in scattering from four molecular systems; myoglobin; ubiquitin; alcohol dehydrogenase; and HIV protease; and demonstrate the modulation of these ensembles by ligand binding, mutation, and environmental factors. The observations are analyzed quantitatively in terms of the average spatial extent of structural fluctuations occurring within these proteins under different experimental conditions. The insights which these analyses support are discussed in terms of the function of the various proteins. 相似文献
43.
Schoor S Farrow S Blaschke H Lee S Perry G von Schwartzenberg K Emery N Moffatt B 《Plant physiology》2011,157(2):659-672
Purine salvage enzymes have been implicated, but not proven, to be involved in the interconversion of cytokinin (CK) bases, ribosides, and nucleotides. Here, we use Arabidopsis (Arabidopsis thaliana) lines silenced in adenosine kinase (ADK) expression to understand the contributions of this enzyme activity to in vivo CK metabolism. Both small interfering RNA- and artificial microRNA-mediated silencing of ADK led to impaired root growth, small, crinkled rosette leaves, and reduced apical dominance. Further examination of ADK-deficient roots and leaves revealed their irregular cell division. Root tips had uneven arrangements of root cap cells, reduced meristem sizes, and enlarged cells in the elongation zone; rosette leaves exhibited decreased cell size but increased cell abundance. Expression patterns of the cyclinB1;1::β-glucuronidase and Arabidopsis Response Regulator5::β-glucuronidase reporters in the ADK-deficient background were consistent with altered cell division and an increase in CK activity, respectively. In vivo feeding of ADK-deficient leaves with radiolabeled CK ribosides of isopentenyladenosine and zeatin showed a decreased flux into the corresponding CK nucleotides. Comprehensive high-performance liquid chromatography-tandem mass spectrometry analysis detected significantly higher levels of active CK ribosides in both sense ADK and artificial microADK. Taken together, these metabolic and phenotypic analyses of ADK-deficient lines indicate that ADK contributes to CK homeostasis in vivo. 相似文献
44.
Kasson PM Zomorodian A Park S Singhal N Guibas LJ Pande VS 《Bioinformatics (Oxford, England)》2007,23(14):1753-1759
MOTIVATION: Membrane fusion constitutes a key stage in cellular processes such as synaptic neurotransmission and infection by enveloped viruses. Current experimental assays for fusion have thus far been unable to resolve early fusion events in fine structural detail. We have previously used molecular dynamics simulations to develop mechanistic models of fusion by small lipid vesicles. Here, we introduce a novel structural measurement of vesicle topology and fusion geometry: persistent voids. RESULTS: Persistent voids calculations enable systematic measurement of structural changes in vesicle fusion by assessing fusion stalk widths. They also constitute a generally applicable technique for assessing lipid topological change. We use persistent voids to compute dynamic relationships between hemifusion neck widening and formation of a full fusion pore in our simulation data. We predict that a tightly coordinated process of hemifusion neck expansion and pore formation is responsible for the rapid vesicle fusion mechanism, while isolated enlargement of the hemifusion diaphragm leads to the formation of a metastable hemifused intermediate. These findings suggest that rapid fusion between small vesicles proceeds via a small hemifusion diaphragm rather than a fully expanded one. AVAILABILITY: Software available upon request pending public release. SUPPLEMENTARY INFORMATION: Supplementary data are available on Bioinformatics online. 相似文献
45.
High mobility group box‐1 (HMGB‐1) is a DNA binding nuclear protein and pro‐inflammatory cytokine. The box A domain of HMGB‐1 (rHMGB‐1A) exerts an anti‐inflammatory effect, inhibiting wild‐type HMGB‐1 (wtHMGB‐1). In this study, HMGB‐1A was evaluated as an siRNA carrier with anti‐inflammatory effects. HMGB‐1A was expressed and purified by consecutive nickel chelate chromatography, cationic exchange chromatography, and polymixin B chromatography. Purified rHMGB‐1A demonstrated an anti‐inflammatory effect, reducing tumor necrosis factor‐α (TNF‐α) in wtHMGB‐1 or lipopolysaccharide (LPS) activated macrophages. In gel retardation assay, rHMGB‐1A formed a stable complex with siRNA at or above a 1:2 weight ratio (siRNA:rHMGB‐1A). A heparin competition assay showed that an siRNA/rHMGB‐1A complex released siRNA more easily than an siRNA/polyethylenimine (PEI, 25 kDa) complex. Luciferase siRNA/rHMGB‐1A reduced firefly luciferase expression at a similar level as luciferase siRNA/PEI complex. Furthermore, TNF‐α siRNA/rHMGB‐1A synergistically reduced TNF‐α expression in LPS activated macrophages. Therefore, rHMGB‐1A may be useful as an siRNA carrier with anti‐inflammatory effects in siRNA therapy for various inflammatory diseases. J. Cell. Biochem. 113: 122–131, 2012. © 2011 Wiley Periodicals, Inc. 相似文献
46.
Lee Sang Il Lee Keon Jin Chun Ho Hyun Ha Sanghyun Gwak Hyun Jung Kim Ho Myeong Lee Jong-Hee Choi Hak-Jong Kim Hyeong Hwan Shin Teak Soo Park Hae Woong Kim Jin-Cheol 《Bioprocess and biosystems engineering》2018,41(3):345-352
Bioprocess and Biosystems Engineering - Oxalic acid has potent nematicidal activity against the root-knot nematode Meloidogyne incognita. In this study, fermentation parameters for oxalic acid... 相似文献
47.
Overexpression of defense response genes in transgenic wheat enhances resistance to Fusarium head blight 总被引:2,自引:0,他引:2
Mackintosh CA Lewis J Radmer LE Shin S Heinen SJ Smith LA Wyckoff MN Dill-Macky R Evans CK Kravchenko S Baldridge GD Zeyen RJ Muehlbauer GJ 《Plant cell reports》2007,26(4):479-488
Fusarium head blight (FHB) of wheat, caused by Fusarium graminearum and other Fusarium species, is a major disease problem for wheat production worldwide. To combat this problem, large-scale
breeding efforts have been established. Although progress has been made through standard breeding approaches, the level of
resistance attained is insufficient to withstand epidemic conditions. Genetic engineering provides an alternative approach
to enhance the level of resistance. Many defense response genes are induced in wheat during F. graminearum infection and may play a role in reducing FHB. The objectives of this study were (1) to develop transgenic wheat overexpressing
the defense response genes α-1-purothionin, thaumatin-like protein 1 (tlp-1), and β-1,3-glucanase; and (2) to test the resultant
transgenic wheat lines against F. graminearum infection under greenhouse and field conditions. Using the wheat cultivar Bobwhite, we developed one, two, and four lines
carrying the α-1-purothionin, tlp-1, and β-1,3-glucanase transgenes, respectively, that had statistically significant reductions
in FHB severity in greenhouse evaluations. We tested these seven transgenic lines under field conditions for percent FHB disease
severity, deoxynivalenol (DON) mycotoxin accumulation, and percent visually scabby kernels (VSK). Six of the seven lines differed
from the nontransgenic parental Bobwhite line for at least one of the disease traits. A β-1,3-glucanase transgenic line had
enhanced resistance, showing lower FHB severity, DON concentration, and percent VSK compared to Bobwhite. Taken together,
the results showed that overexpression of defense response genes in wheat could enhance the FHB resistance in both greenhouse
and field conditions. 相似文献
48.
Boosting Power‐Generating Performance of Triboelectric Nanogenerators via Artificial Control of Ferroelectric Polarization and Dielectric Properties 下载免费PDF全文
Wanchul Seung Hong‐Joon Yoon Tae Yun Kim Hanjun Ryu Jihye Kim Ju‐Hyuck Lee Jeong Hwan Lee Sanghyun Kim Yun Kwon Park Young Jun Park Sang‐Woo Kim 《Liver Transplantation》2017,7(2)
Low output current represents a critical challenge that has interrupted the use of triboelectric nanogenerators (TNGs) in a wide range of applications as sustainable power sources. Many approaches (e.g., operation at high frequency, parallel stacks of individual devices, and hybridization with other energy harvesters) remain limited in solving the challenge of low output current from TNGs. Here, a nanocomposite material system having a superior surface charge density as a triboelectric active material is reported. The nanocomposite material consists of a high dielectric ceramic material, barium titanate, showing great charge‐trapping capability, together with a ferroelectric copolymer matrix, Poly(vinylidenefluoride‐co‐trifluoroethylene) (P(VDF‐TrFE)), with electrically manipulated polarization with strong triboelectric charge transfer characteristics. Based on a contact potential difference study showing that poled P(VDF‐TrFE) has 18 times higher charge attracting properties, a fraction between two components is optimized. Boosting power‐generating performance is achieved for 1130 V of output voltage and 1.5 mA of output current with this ferroelectric composite‐based TNG, under 6 kgf of pushing force at 5 Hz. An enormously faster charging property than traditional polymer film‐based TNGs is demonstrated in this study. Finally, the charging of a self‐powering smartwatch with a charging management circuit system with no external power sources is demonstrated successfully. 相似文献
49.
Jun Yeon Park Hyun Young Kim Takayuki Shibamoto Tae Su Jang Sang Cheon Lee Jae Suk Shim Dae-Hyun Hahm Hae-Jeung Lee Sanghyun Lee Ki Sung Kang 《Bioorganic & medicinal chemistry letters》2017,27(17):3968-3973
The biological activities of the ethanol extract from Cirsium japonicum var. maackii (ICF-1) and its major component, polyphenol cirsimaritin, were investigated as part of the search for possible alternative drugs for breast cancer. Three in vitro cell-based assays were used: the cell proliferation assay, tube-formation assay, and Western blot analysis. Both the ICF-1 extract and cirsimaritin inhibited the viability of HUVECs in a dose-dependent manner. The inhibition achieved was 36.89% at a level of 200 μg/ml by the ICF-1 extract and 62.04% at a level of 100 μM by cirsimaritin. The ICF-1 extract and cirsimaritin reduced tube formation by 12.69% at level of 25 μg/ml and 32.18% at the levels of 6.25 μM, respectively. Cirsimaritin inhibited angiogenesis by downregulation of VEGF, p-Akt and p-ERK in MDA-MB-231 cells, suggesting that cirsimaritin is potentially useful as an anti-metastatic agent. The present study demonstrated that Cirsium japonicum extract and its active component cirsimaritin is an excellent candidate as an alternative anti-breast cancer drug. 相似文献
50.
Forrest C. Walker Ebrahim Hassan Stefan T. Peterson Rachel Rodgers Lawrence A. Schriefer Cassandra E. Thompson Yuhao Li Gowri Kalugotla Carla Blum-Johnston Dylan Lawrence Broc T. McCune Vincent R. Graziano Larissa Lushniak Sanghyun Lee Alexa N. Roth Stephanie M. Karst Timothy J. Nice Jonathan J. Miner Craig B. Wilen Megan T. Baldridge 《PLoS pathogens》2021,17(3)
Interferons (IFNs) are key controllers of viral replication, with intact IFN responses suppressing virus growth and spread. Using the murine norovirus (MNoV) system, we show that IFNs exert selective pressure to limit the pathogenic evolutionary potential of this enteric virus. In animals lacking type I IFN signaling, the nonlethal MNoV strain CR6 rapidly acquired enhanced virulence via conversion of a single nucleotide. This nucleotide change resulted in amino acid substitution F514I in the viral capsid, which led to >10,000-fold higher replication in systemic organs including the brain. Pathogenicity was mediated by enhanced recruitment and infection of intestinal myeloid cells and increased extraintestinal dissemination of virus. Interestingly, the trade-off for this mutation was reduced fitness in an IFN-competent host, in which CR6 bearing F514I exhibited decreased intestinal replication and shedding. In an immunodeficient context, a spontaneous amino acid change can thus convert a relatively avirulent viral strain into a lethal pathogen. 相似文献