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971.
Comparing gene discovery from Affymetrix GeneChip microarrays and Clontech PCR-select cDNA subtraction: a case study 总被引:1,自引:0,他引:1
972.
973.
Syka JE Marto JA Bai DL Horning S Senko MW Schwartz JC Ueberheide B Garcia B Busby S Muratore T Shabanowitz J Hunt DF 《Journal of proteome research》2004,3(3):621-626
We describe the design and performance of a prototype high performance hybrid mass spectrometer. This instrument consists of a linear quadrupole ion trap (QLT) coupled to a Fourier transform ion cyclotron resonance mass analyzer (FTMS). This configuration provides rapid and automated MS and MS/MS analyses, similar to the "data dependent scanning" found on standard 3-D Paul traps, but with substantially improved internal scan dynamic range, mass measurement accuracy, mass resolution, and detection limits. Sequence analysis of peptides at the zeptomole level is described. The recently released, commercial version of this instrument operates in the LC/MS mode (1 s/scan) with a mass resolution of 100 000 and is equipped with automatic gain control to provide mass measurement accuracy of 1-2 ppm without internal standard. Methodology is described that uses this instrument to compare the post-translational modifications present on histone H3 isolated from asynchronously growing cells and cells arrested in mitosis. 相似文献
974.
Grieshammer U Le Ma Plump AS Wang F Tessier-Lavigne M Martin GR 《Developmental cell》2004,6(5):709-717
Kidney development occurs in a stereotypic position along the body axis. It begins when a single ureteric bud emerges from the nephric duct in response to GDNF secreted by the adjacent nephrogenic mesenchyme. Posterior restriction of Gdnf expression is considered critical for correct positioning of ureteric bud development. Here we show that mouse mutants lacking either SLIT2 or its receptor ROBO2, molecules known primarily for their function in axon guidance and cell migration, develop supernumerary ureteric buds that remain inappropriately connected to the nephric duct, and that the SLIT2/ROBO2 signal is transduced in the nephrogenic mesenchyme. Furthermore, we show that Gdnf expression is inappropriately maintained in anterior nephrogenic mesenchyme in these mutants. Thus our data identify an intercellular signaling system that restricts, directly or indirectly, the extent of the Gdnf expression domain, thereby precisely positioning the site of kidney induction. 相似文献
975.
Ferguson MR Fan X Mukherjee M Luo J Khan R Ferreon JC Hilser VJ Shope RE Fox RO 《Protein science : a publication of the Protein Society》2004,13(3):626-632
The Caenorhabditis elegans SEM-5 SH3 domains recognize proline-rich peptide segments with modest affinity. We developed a bivalent peptide ligand that contains a naturally occurring proline-rich binding sequence, tethered by a glycine linker to a disulfide-closed loop segment containing six variable residues. The glycine linker allows the loop segment to explore regions of greatest diversity in sequence and structure of the SH3 domain: the RT and n-Src loops. The bivalent ligand was optimized using phage display, leading to a peptide (PP-G(4)-L) with 1000-fold increased affinity for the SEM-5 C-terminal SH3 domain over that of a natural ligand. NMR analysis of the complex confirms that the peptide loop segment is targeted to the RT and n-Src loops and parts of the beta-sheet scaffold of this SH3 domain. This binding region is comparable to that targeted by a natural non-PXXP peptide to the p67(phox) SH3 domain, a region not known to be targeted in the Grb2 SH3 domain family. PP-G(4)-L may aid in the discovery of additional binding partners of Grb2 family SH3 domains. 相似文献
976.
On the basis of visual assessment of figure drawings and front/profile images, past researchers believed that the waist-hip ratio (WHR) and the body mass index (BMI) were two putative cues to female physical attractiveness. However, this view was not tested on three-dimensional (3D) female images. In the present study, 3D images of 31 Caucasian females having varying body weights (BMI ranged from 16 to 35) were shown to 29 male and 25 female viewers, who were asked to rate the physical attractiveness. The results showed that the body volume divided by the square of the height, defined as volume height index (VHI), is the most important and direct visual determinant of female physical attractiveness. In determining the female attractiveness, human observers may first use VHI as a visual cue, which is also a key indicator of health and fertility owing to its strong linear relation to BMI. To fine-tune the judgement, observers may then use body proportions, the most important of which are the ratio of waist height over the chin height (WHC) (a measure of the length of legs over total tallness) and the deviation of WHR from the ideal ratio. It also appears that the effect of the body's physical parameters on the perception of female physical attractiveness conforms to Stevens' power law of psychophysics. 相似文献
977.
Fan J Wang X Wu L Matsumoto SI Liang J Koike T Ichikawa T Sun H Shikama H Sasaguri Y Watanabe T 《Transgenic research》2004,13(3):261-269
Increased matrix metalloproteinase-12 (MMP-12) has been implicated in atherosclerosis and many other inflammatory processes.
To define MMP-12 functions in vivo, we generated transgenic rabbits that expressed human (h) MMP-12 gene under the control of a macrophage-specific promoter,
the human scavenger receptor promoter. Two transgenic founder rabbits were found to have hMMP-12 transgene integration by
Southern blot analysis. hMMP-12 mRNA was expressed in peritoneal and alveolar macrophages, and in tissues enriched in macrophages
in transgenic rabbits. High levels of hMMP-12 protein were detected in the conditioned media of cultured peritoneal and alveolar
macrophages from transgenic rabbits. Zymography showed that hMMP-12 secreted from macrophages possessed enzymatic activity
toward β-casein. To evaluate the expression of hMMP-12 in inflammatory sites, we used carrageenan-induced granulomas as an
in vivo model for tissue macrophages and foam cells. Granuloma size in transgenic rabbits was significantly increased compared to
that in control rabbits, and histological examination revealed that granulomas of transgenic rabbits were enriched in macrophages
associated with increased hMMP-12 expression. We believe that this transgenic rabbit model with increased expression of hMMP-12
may become a useful model for further mechanistic studies of MMP-12 in inflammatory diseases and cancer invasion; it is also
an ideal model for testing the in vivo action of MMP-12 inhibitors. 相似文献
978.
Three new prenylflavonoids, namely corylifols A-C (1-3), together with 13 known ones, were isolated from the seeds of Psoralea corylifolia. Their structures were elucidated by spectral methods including 1D and 2D NMR techniques. All the isolates were tested on antibacterial assays, and nine of them showed significant antibacterial activities against two pathogenic bacteria Staphylococcus aureus and S. epidermidis. The antibacterial structure-activity relationship of these prenylflavonoids (1-16) was also briefly discussed. 相似文献
979.
980.
低氧对胚胎干细胞增殖的影响 总被引:4,自引:1,他引:3
目的:观察间歇性低氧和持续性低氧对体外培养的胚胎干细胞(ES细胞)增殖的影响.方法:利用细胞记数法和BrdU (5-溴脱氧尿苷)掺入的流式细胞分析检测细胞增殖,并用RT -PCR的方法检测低氧诱导因子(HIF-1a)的表达变化.结果:①将ES细胞分别放在低氧(3%~10% O2)和常氧(20% O2)的环境中培养24 h后,在低氧环境中培养的ES细胞数较常氧组明显减少;②将ES细胞分别给予间歇性低氧刺激(3%~10% O2),每天10 min,连续4 d后,发现3%低氧组较常氧对照组的细胞增殖明显升高.③用RT-PCR方法观察HIF-1a的表达与细胞增殖的关系,发现在常氧环境中培养的ES即有HIF-1a的表达,ES细胞在持续低氧24 h或间歇性低氧(3%~10% O2)刺激4 d后对HIF-1a的表达均无明显影响.结论:间歇性低氧(3% O2)可明显促进体外培养的ES细胞增殖,而持续性低氧抑制ES细胞增殖,间歇性低氧(3% O2)刺激促进ES细胞增殖的机制尚有待于进一步的研究. 相似文献