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排序方式: 共有169条查询结果,搜索用时 15 毫秒
1.
Owing to the exceptional intracellular distribution and the heterogeneous expression pattern during transformation and metastasis
in various tumors, the EF-hand calcium-binding protein S100A2 attracts increasing attention. Unlike the majority of S100 proteins,
S100A2 expression is downregulated in many cancers and the loss in nuclear expression has been associated with poor prognosis.
On the other hand, S100A2 is upregulated in some cancers. This mini review highlights the general characteristics of S100A2
and discusses recent findings on its putative functional implication as a suppressor or promoter in cancerogenesis. 相似文献
2.
Collaborative study on the isolation of salmonella from artificially contaminated milk powder 总被引:1,自引:0,他引:1
H J Beckers F M van Leusden D Roberts O Pietzsch T H Price M van Schothorst P D Tips P Vassiliadis E H Kampelmacher 《The Journal of applied bacteriology》1985,59(1):35-40
The suitability of artificially contaminated milk powder as a substrate for salmonella reference samples and its stability under different storage conditions were studied. The need for a reconstitution step in the standard isolation method for salmonellas from milk powders was also investigated. When milk powder was examined in this way with a reconstitution step, differences in laboratory methods and/or storage times had no significant effect on the results after storage at 4 degrees C. With powder stored at room temperature there was a systematic decrease in the number of samples positive as the storage time increased. It is concluded therefore that milk powder contaminated with salmonellas should be stored at 4 degrees C. Examination of such milk powder with a reconstitution step yielded better results than without it and this step is therefore necessary for improving the reproducibility of the method. No significant differences were encountered between the standard isolation method and that used in the authors' laboratories. The results of this study indicate that milk powder is suitable as basic material for reference samples and that a reconstitution step should be included in the standard salmonella isolation procedure. 相似文献
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Christoph Tondera Markus Laube Christin Wimmer Torsten Kniess Birgit Mosch Kay Großmann Jens Pietzsch 《Biochemical and biophysical research communications》2013,430(1):301-306
This study aimed at visualization of cyclooxygenase-2 (COX-2) protein expression in melanoma cells by confocal laser induced cryofluorescence microscopy using 4-(3-(4-methoxyphenyl)-1H-indol-2-yl)benzene-sulfonamide (C1) representative for a novel class of autofluorescent 2,3-diarylsubstituted indole-based selective COX-2 inhibitors.COX-2 expression was measured in human melanoma cell lines A2058 and MelJuso by immunocytochemistry and immunoblotting. Cellular uptake experiments using varying C1 concentrations down to 0.1 nM (with/without molar excess of celecoxib as control) were performed at 37 °C. Cryofluorescence microscopy was conducted at 20 K.COX-2 protein expression was successfully visualized by C1 in A2058 cells. COX-2-negative MelJuso cells showed no specific accumulation of C1. Control experiments using celecoxib and, additionally, implemented fluorescence spectroscopy confirmed specificity of both cellular uptake and intracellular association of C1.Cryofluorescence microscopy in combination with spectroscopy allowed for visualization of COX-2 protein expression in melanoma cells in vitro using a selective COX-2 inhibitor at very low concentrations. 相似文献
6.
Increased thermostability of microbial transglutaminase by combination of several hot spots evolved by random and saturation mutagenesis 总被引:1,自引:0,他引:1
The thermostability of microbial transglutaminase (MTG) of Streptomyces mobaraensis was further improved by saturation mutagenesis and DNA-shuffling. High-throughput screening was used to identify clones with increased thermostability at 55°C. Saturation mutagenesis was performed at seven "hot spots", previously evolved by random mutagenesis. Mutations at four positions (2, 23, 269, and 294) led to higher thermostability. The variants with single amino acid exchanges comprising the highest thermostabilities were combined by DNA-shuffling. A library of 1,500 clones was screened and variants showing the highest ratio of activities after incubation for 30 min at 55°C relative to a control at 37°C were selected. 116 mutants of this library showed an increased thermostability and 2 clones per deep well plate were sequenced (35 clones). 13 clones showed only the desired sites without additional point mutations and eight variants were purified and characterized. The most thermostable mutant (triple mutant S23V-Y24N-K294L) exhibited a 12-fold higher half-life at 60°C and a 10-fold higher half-life at 50°C compared to the unmodified recombinant wild-type enzyme. From the characterization of different triple mutants differing only in one amino acid residue, it can be concluded that position 294 is especially important for thermostabilization. The simultaneous exchange of amino acids at sites 23, 24, 269 and 289 resulted in a MTG-variant with nearly twofold higher specific activity and a temperature optimum of 55°C. A triple mutant with amino acid substitutions at sites 2, 289 and 294 exhibits a temperature optimum of 60°C, which is 10°C higher than that of the wild-type enzyme. 相似文献
7.
The present study analyzed the drosophilid assemblages in different levels of urbanization in the city of Porto Alegre, Rio Grande do Sul, Brazil. Collections were carried out in 2008 in three different environments: a highly urbanized area????Jardim Botanico,?? a forested area with intermediary urbanization????Parque Gabriel Knijnik,?? and in a relatively well-preserved forested area, although threatened by the urban growth????Morro Santana.?? In Jardim Botanico, 36 species belonging to four genera were found, with high abundance of exotic species as Drosophila simulans Sturtevant and Zaprionus indianus (Gupta). In Parque Gabriel Knijnik, 33 species that belonged to four genera were found, with higher abundances of native species belonging to the Drosophila tripunctata species group and Drosophila willistoni species subgroup, and lower abundance of exotic species. As for Morro Santana, 32 species and three genera were found, with higher abundances of native groups, low representativeness of exotic species, and absence of Zaprionus indianus. The analysis of the Jaccard index showed higher similarity in the species composition between samples collected in summer and autumn, and between samples collected in winter and spring. On the other hand, the Morisita index differentiated Jardim Botanico from the other two studied sites. Our results show that Morro Santana is an important area of native biodiversity, reinforcing, therefore, the inclusion of this area in the project for the creation of an ecological corridor as proposed by the Ministry of the Environment of Brazil. 相似文献
8.
Mouquet H Klein F Scheid JF Warncke M Pietzsch J Oliveira TY Velinzon K Seaman MS Nussenzweig MC 《PloS one》2011,6(9):e24078
Understanding the antibody response to HIV-1 in humans that show broad neutralizing serologic activity is a crucial step in trying to reproduce such responses by vaccination. Investigating antibodies with cross clade reactivity is particularly important as these antibodies may target conserved epitopes on the HIV envelope gp160 protein. To this end we have used a clade B YU-2 gp140 trimeric antigen and single-cell antibody cloning methods to obtain 189 new anti-gp140 antibodies representing 51 independent B cell clones from the IgG memory B cells of 3 patients infected with HIV-1 clade A or B viruses and exhibiting broad neutralizing serologic activity. Our results support previous findings showing a diverse antibody response to HIV gp140 envelope protein, characterized by differentially expanded B-cell clones producing highly hypermutated antibodies with heterogenous gp140-specificity and neutralizing activity. In addition to their high-affinity binding to the HIV spike, the vast majority of the new anti-gp140 antibodies are also polyreactive. Although none of the new antibodies are as broad or potent as VRC01 or PG9, two clonally-related antibodies isolated from a clade A HIV-1 infected donor, directed against the gp120 variable loop 3, rank in the top 5% of the neutralizers identified in our large collection of 185 unique gp140-specific antibodies in terms of breadth and potency. 相似文献
9.
Background
In the analysis of complex traits, genetic effects can be confounded with non-genetic effects, especially when using full-sib families. Dominance and epistatic effects are typically confounded with additive genetic and non-genetic effects. This confounding may cause the estimated genetic variance components to be inaccurate and biased.Methods
In this study, we constructed genetic covariance structures from whole-genome marker data, and thus used realized relationship matrices to estimate variance components in a heterogenous population of ~ 2200 mice for which four complex traits were investigated. These mice were genotyped for more than 10,000 single nucleotide polymorphisms (SNP) and the variances due to family, cage and genetic effects were estimated by models based on pedigree information only, aggregate SNP information, and model selection for specific SNP effects.Results and conclusions
We show that the use of genome-wide SNP information can disentangle confounding factors to estimate genetic variances by separating genetic and non-genetic effects. The estimated variance components using realized relationship were more accurate and less biased, compared to those based on pedigree information only. Models that allow the selection of individual SNP in addition to fitting a relationship matrix are more efficient for traits with a significant dominance variance. 相似文献10.