Identification of c-type heme-containing peptides using nonactivated immobilized metal affinity chromatography resin enrichment and higher-energy collisional dissociation

The c-type cytochromes play essential roles in many biological activities of both prokaryotic and eukaryotic cells, including electron transfer, enzyme catalysis, and induction of apoptosis. We report a novel enrichment strategy for identifying c-type heme-containing peptides that uses nonactivated IMAC resin. The strategy demonstrated at least 7-fold enrichment for heme-containing peptides digested from a cytochrome c protein standard, and quantitative linear performance was also assessed for heme-containing peptide enrichment. Heme-containing peptides extracted from the periplasmic fraction of Shewanella oneidensis MR-1 were further identified using higher-energy collisional dissociation tandem mass spectrometry. The results demonstrated the applicability of this enrichment strategy to identify c-type heme-containing peptides from a highly complex biological sample and, at the same time, confirmed the periplasmic localization of heme-containing proteins during suboxic respiration activities of S. oneidensis MR-1.     

减少BT下载的资源占用

经常使用BT下载的用户一定会有资源占用太大 的感触,其实只要略加设置,我们也可以把系统资源 降低不少。这里以BitComet例,在“选项／界 面与外观中”把“最小化到系统托盘”选项勾掉, 让BitComet留在任务栏的话,系统内存资源占用 明显下降不少。不过值得注意的是,系统所用内存 总量是基本没有什么变化的(如图1、2)。     

Standardized evaluation methodology for 2-D-3-D registration

In the past few years, a number of two-dimensional (2-D) to three-dimensional (3-D) (2-D-3-D) registration algorithms have been introduced. However, these methods have been developed and evaluated for specific applications, and have not been directly compared. Understanding and evaluating their performance is therefore an open and important issue. To address this challenge we introduce a standardized evaluation methodology, which can be used for all types of 2-D-3-D registration methods and for different applications and anatomies. Our evaluation methodology uses the calibrated geometry of a 3-D rotational X-ray (3DRX) imaging system (Philips Medical Systems, Best, The Netherlands) in combination with image-based 3-D-3-D registration for attaining a highly accurate gold standard for 2-D X-ray to 3-D MR/CT/3DRX registration. Furthermore, we propose standardized starting positions and failure criteria to allow future researchers to directly compare their methods. As an illustration, the proposed methodology has been used to evaluate the performance of two 2-D-3-D registration techniques, viz. a gradient-based and an intensity-based method, for images of the spine. The data and gold standard transformations are available on the internet (http://www.isi.uu.nl/Research/Databases/).     

Rapid forensic analysis and identification of ''lilac'' architectural finishes using Raman spectroscopy

The potential of Raman spectroscopy to discriminate between architectural finishes (household paint) has been investigated using a test set of 51 'lilac' paints and three different excitation wavelengths. The spectra obtained with visible excitation typically displayed a series of intense Raman bands on a featureless fluorescence background but the spectra of all the paints studied had essentially identical bands. With 785 nm excitation, although the same bands that dominated the 514 nm spectra were still observed, other bands with comparable intensity also appeared. The two strongest scattering constituents were identified as a dioxazine dye, Violet 23 and beta-Cu(phthalocyanine). A scatter plot of the intensities of marker bands for these constituents (normalized to the strong rutile bands that were always present) showed that, despite the fact that the sample set spanned a wide range of rutile : dioxazine dye : phthalo- cyanine ratios, many of the samples had very similar ratios and could not be discriminated. However, all the samples (even those with similar relative proportions of the main constituents) could be discriminated on the basis of their minor constituents, either by manually measuring band intensities or through the creation and searching of spectral libraries.     

Toward in-cylinder absorption tomography in a production engine

Design requirements for an 8000 frame/s dual-wavelength ratiometric chemical species tomography system, intended for hydrocarbon vapor imaging in one cylinder of a standard automobile engine, are examined. The design process is guided by spectroscopic measurements on iso-octane and by comprehensive results from laboratory phantoms and research engines, including results on temporal resolution performance. Novel image reconstruction techniques, necessary for this application, are presented. Recent progress toward implementation, including details of the optical access arrangement employed and signal-to-noise issues, is described. We present first cross-cylinder IR absorption measurements from a reduced channel-count (nontomographic) system and discuss the prospects for imaging.     

Enhanced undecylprodigiosin production from Serratia marcescens SS-1 by medium formulation and amino-acid supplementation

Serratia marcescens Simon Swift-1 (SS-1) was used to produce a prodigiosin-like pigment, undecylprodigiosin (UP), known to have antitumor activities and potential as an anticancer drug. Modified media containing components of Luria-Bertani (LB) broth and selected amino acids were used to improve UP production from S. marcescens SS-1. Optimal culture conditions (e.g., temperature, pH, agitation rate) for UP production were also identified. It was found that S. marcescens SS-1 was able to produce 690 mg l-1 of UP when it was grown with 5 g l-1 yeast extract alone (YE medium) under the optimal culture conditions of 30 degrees C, 200 rpm, and pH 8. The UP production of 690 mg l-1 is nearly 23-fold of that obtained from original LB medium. Addition of amino acids containing pyrrole-like structures further enhanced UP production. Nearly 2 and 1.4 g l-1 of UP was produced when the SS-1 strain was cultivated with YE medium supplemented with proline and histidine (5 g l-1), respectively. Moreover, the addition of aspartic acid (5 g l-1) also resulted in a high UP production of 1.4 g l-1. Optimal dosages of the three amino acids were subsequently determined and the highest UP production (2.5 g l-1) was achieved with the addition of 10 g l-1 of proline. This suggests that the supplementation of amino acids related to the formation of a UP precursor (e.g., pyrrolylpyrromethene) could enhance UP production by the SS-1 strain.