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31.
Chen X  Li Y  Wei K  Li L  Liu W  Zhu Y  Qiu Z  He F 《The Journal of biological chemistry》2003,278(49):49022-49030
Hepatopoietin (HPO) is a novel hepatotrophic growth factor that stimulates hepatocyte proliferation by two pathways. In the first, intracellular HPO specifically modulates the activator protein-1 (AP-1) pathway through JAB1 (Jun activation domain-binding protein 1), whereas in the second, extracellular HPO triggers the mitogen-activated protein kinase pathway by binding its specific receptor on the cell surface. In this report we demonstrate that HPO is a flavin-linked sulfhydryl oxidase, and the invariant CXXC (Cys-Xaa-Xaa-Cys) motif in HPO is essential for the enzyme activity of HPO but not for its dimerization nor for its binding ability with JAB1. Two intramolecular disulfides were identified in HPO by mass spectrometry, one of which is formed by the redox CXXC cysteine residues. HPO site-directed mutants (Cys/Ser) at active sites, which lost sulfhydryl oxidase activity, could not increase c-Jun phosphorylation and failed to potentiate JAB1-mediated AP-1 activation. However, the mutants still have mitogenic stimulation and mitogen-activated protein kinase activation effects on HepG2 cells. Thus, it can be concluded that the potentiation role of HPO on AP-1 is dependent on its sulfhydryl oxidase activity.  相似文献   
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The CD155 ligand CD96 is an immunoglobulin-like protein tentatively allocated to the repertoire of human NK receptors. We report here that the CD96/CD155-interaction is preserved between man and mouse although both receptors are only moderately conserved in amino acid sequence. Moreover, murine CD96 (mCD96) binds to nectin-1, a receptor related to CD155. Applying newly generated monoclonal antibodies specifically recognizing mCD96, an expression profile is revealed resembling closely that of human CD96 (hCD96) on cells of hematopoietic origin. A panel of anti-mCD96 but also recently established anti-mCD155 antibodies effectively prevents formation of CD96/CD155-complexes. This was exploited to demonstrate that the only available receptor for mCD96 present on thymocytes is mCD155. Moreover, T cell adhesion to insect cells expressing mCD155 is blocked by these antibodies depending on the T cell subtype. These results suggest a function of the CD96/CD155-adhesion system in T cell biology.  相似文献   
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半干旱黄土高原地区春小麦地膜覆盖研究概述   总被引:7,自引:0,他引:7  
在黄土高原半干旱地区春小麦上进行的地膜覆盖试验表明,地膜覆盖通过改善耕层土壤生态环境条件,即通过改善水,热状况,活化土壤养分,对提高水分和养分利用效率,实现粮食增产具有重要作用,但近年来在生产实践和科学实验中发现,不合理的长期全生育期地膜覆盖,因在作物生长前期和中期覆膜作物较不覆膜作物生长好,覆膜作物在生长期水分蒸腾损失严重,土壤水分的蒸散(蒸发+蒸腾)损失远比不覆膜土壤严重,在作物生长后期降水少或没有补充灌溉时,会产生严重的水分肋迫现象,显著抑制小穗分化和灌浆,最终导致收获得指数和产量下降,同时,地膜覆盖的增产作用在一定程度上是以耗竭土壤肥力,特别是在有机物质为代 的,因此,不正确的地膜覆盖(如全生育期的地膜覆盖),不仅有时起不到显著的增产作用,而且易造成土壤养分,特别是土壤中硝态氮的累积和损失,肥料利用效率降低,土壤生态条件恶化,下降,难以持续高产,因此在确定地膜覆盖范式时,必须要考虑底墒,作物生育期降水,地膜覆盖的阶段性和氮肥的施用等。  相似文献   
36.
Soluble microbial products (SMPs) are considered as the main organic components in wastewater treatment plant effluent from biological wastewater treatment systems. To investigate and explore SMP metabolism pathway for further treatment and control, two innovative mechanistically based activated sludge models were developed by extension of activated sludge model no.3 (ASM3). One was the model by combining SMP formation and degradation (ASM3-SMP model) processes with ASM3, and the other by combining both SMP and simultaneous substrate storage and growth (SSSG) mechanisms with ASM3 (SSSG-ASM3-SMP model). The detailed schematic modification and process supplements were introduced for comprehensively understanding all the mechanisms involved in the activated sludge process. The evaluations of these two models were demonstrated by a laboratory-scale sequencing batch reactor (SBR) operated under aerated/non-aerated conditions. The simulated and measured results indicated that SMP comprised about 83% of total soluble chemical oxygen demand (SCOD) in which biomass-associated products (BAPs) were predominant compared with utilization-associated products (UAPs). It also elucidated that there should be a minimum SMP value as the reactive time increases continuously and this conclusion could be used to optimize effluent SCOD in activated sludge processes. The comparative results among ASM3, ASM3-SMP and SSSG-ASM3-SMP models and the experimental measurements (SCOD, ammonia and nitrate nitrogen) showed clearly the best agreement with SSSG-ASM3-SMP simulation values (R = 0.993), strongly suggesting that both SMP formation and degradation and SSSG mechanisms are necessary in biologically activated sludge modeling for municipal wastewater treatment.  相似文献   
37.
Human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) hold great potential for their therapeutic use in various clinical diseases. Many publications have reported on human blood-derived alternatives to animal serum for culturing mesenchymal stem cells, such as human serum, allogenic umbilical cord blood serum, and human platelet derivatives. However, it is not clear whether human umbilical cord blood plasma (UCBP), as the surplusage of umbilical cord blood mesenchymal stem cell extraction, could be used. In this study, in order to make the best of umbilical cord blood, the human UCBP was dialyzed to replace fetal bovine serum (FBS) in the culture medium. hUC-MSCs were cultured in the new medium. Cell growth rate, specific biomarkers, and differentiation properties were detected to characterize the cell proliferation and MSC-specific properties. The hUC-MSCs cultured in such derived medium were verified with proliferation rate, cluster differentiation markers, cell cycle, as well as differentiation capabilities. Such dialyzed human UCBP is fully comparable with, if not superior to, FBS in deriving and culturing hUC-MSCs.  相似文献   
38.
The bacterial community and diversity in healthy and diseased konjac rhizosphere soils with different ages of continuous cropping were investigated using next-generation sequencing. The results demonstrated that the number of years of continuous cropping significantly altered soil bacterial community and diversity. Soil bacterial Shannon diversity index and Chao 1 index decreased with the increasing cropping years of konjac. After 1 year of cropping, the soil exhibited the highest bacterial relative abundance and diversity. Of the 44 bacterial genera (relative abundance ratio of genera greater than 0.3%), 14 were significantly affected by the duration of continuous cropping and plant status. With increasing continuous cropping, Alicyclobacillus decreased, while Achromobacter, Lactobacillus, Kaistobacter, Rhodoplanes increased after 3 years continuous cropping. Continuous cropping altered the structure and composition of the soil bacterial community, which led to the reduction in the beneficial bacteria and multiplication of harmful bacteria. These results will improve our understanding of soil microbial community regulation and soil health maintenance in konjac farm systems.  相似文献   
39.
Tripartite motif containing 22 (TRIM22), a member of the TRIM/RBCC family, has been reported to activate the nuclear factor-kappa B (NF-κB) pathway in unstimulated macrophage cell lines, but the detailed mechanisms governing this activation remains unclear. We investigated this mechanism in HEK293T cells. We found that overexpression of TRIM22 could activate the NF-κB pathway and conversely, could inhibit the tumor necrosis factor receptor-associated factor 6 (TRAF6)-stimulated NF-κB pathway in HEK293T cells. Further experiments showed that TRIM22 could decrease the self-ubiquitination of TRAF6, and interact with and degrade transforming growth factor-β activated kinase 1 binding protein 2 (TAB2), and that these effects could be partially rescued by a TRIM22 RING domain deletion mutant. Collectively, our data indicate that overexpression of TRIM22 may negatively regulate the TRAF6-stimulated NF-κB pathway by interacting with and degrading TAB2.  相似文献   
40.
Cyclic nucleotide phosphodiesterase 11A (PDE11A) is the newest member in the PDE family. Although the tissue distribution of PDE11A mRNA has been shown, its protein expression pattern has not been well studied. The goal of this report is to investigate the distribution of PDE11A proteins in a wide range of normal and malignant human tissues. We utilized a polyclonal antibody that recognized all four PDE11A isoforms. Its specificity was demonstrated by Western blot analysis on a recombinant human PDE11A protein and native PDE11A proteins in various human tissues. Immunohistochemistry showed that PDE11A is widely expressed. Various degrees of immunoreactivity were observed in the epithelial cells, endothelial cells, and smooth muscle cells of all tissues examined. The highest expression was in the epithelial, endothelial, and smooth muscle cells of the prostate, Leydig, and spermatogenic cells of the testis, the tubule epithelial cells in the kidney, the epithelial and endothelial cells in the adrenal, the epithelial cells and macrophages in the colon, and the epidermis in the skin. Furthermore, PDE11A expression was also detected in several human carcinomas. Our results suggest that PDE11A might be involved in multiple physiological processes in various organs via its ability to modulate intracellular cAMP and cGMP levels.  相似文献   
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