Development of a quantification system of ionic dissociative metabolites using an FT-IR/ATR method

A simultaneous quantification system of ionic dissociative metabolites was developed using a Fourier transform mid-infrared spectroscopic method by focusing our attention on the enzyme reaction from glucose 6-phosphate to fructose 6-phosphate with phosphoglucose isomerase (PGI). We studied the pH dependency of the infrared spectra of the mixture solution for which the PGI reaction was assumed. The infrared spectra of ionic dissociative components in the mixture solution were extracted by multiple linear regression analysis under the assumption of ionic dissociation equilibrium. Additionally, we constructed a simultaneous quantification system using the extracted spectra of the ionic dissociative components on the basis of the ionic dissociation equilibrium. We could accurately estimate the pH value and the concentrations of the ionic dissociative materials in their mixture solution by using this quantification system. In addition, the stability of quantification results for a pK shift was also verified.     

中国芍药组数量化理论Ⅲ──化学分类研究Ⅰ

应用数量化理论Ⅲ原理和方法分析了１３个芍药分类群与６种商品芍药的特征性成分的ＨＰＬＣ图谱的相似性,用三维图形表达各种间,种内的空间位置,根据空间距离大小,比较它们的相似程度,结果与经典分类的分类群间断有一定的相似和不同。     

Fluorometric quantification of green fluorescent protein in tobacco leaf extracts

The main use of green fluorescent protein (GFP) is as a reporter system, where the existence of the protein is usually determined visually using fluorescent microscopy. Although fluorescence-based quantification of GFP is possible, background fluorescence in plants and in plant extracts was observed by our group. Another phenomenon we observed that makes quantification difficult is the increased level of GFP fluorescence in Nicotiana benthamiana leaf extracts, probably the result of dimerization of GFP molecules promoted by interaction with some component(s) of tobacco extracts. In the current work, the background fluorescence was minimized and the enhancement of GFP fluorescence in tobacco extracts was eliminated with the addition of urea to the measured solution so that a simple quantification assay for the GFP in the tobacco extracts could be established.     

Characterization and seasonal variation of individual flavonoids in Zostera marina and Zostera noltii from Norwegian coastal waters

The flavonoid content in leaves of Zostera marina and the endangered Zostera noltii, including mono- and disulphated flavonoids, from different sample localities were characterized. Seasonal variation of both individual and total flavonoid, as well as rosmarinic acid concentration were revealed. Minor amounts of luteolin 7-(6″-malonyl)glucoside (6) and apigenin7-(6″-malonyl)glucoside (11) were identified in Z. noltii for the first time. The total flavonoid content was found to be higher in Z. noltii than in Z. marina at most of the examined localities, and the qualitative flavonoid content was somewhat different in the two species. The quantitative variation of flavonoids and rosmarinic acid was found to be relatively consistent from year to year in Z. marina during a period of three years. The two species appeared though to have a different flavonoid production in the various seasons at the West coast. While Z. marina had the highest content in young leaves in May or June, with a markedly decrease from June to September and the lowest measured content in February, Z. noltii had the lowest measured flavonoid content in May/June followed by an increase from June to September and the highest measured content during wintertime in February. The observed seasonal differences may be related to the fact that Z. noltii is considered a perennial, thermophilous species, and the increasing flavonoid production during the colder seasons from September to March/April in Norway may serve as a protective function.     

Rapid identification and quantification of Collinsella aerofaciens using PCR

The number and incidence of Collinsella aerofaciens in the human intestine are the highest among Gram-positive non-spore-forming bacilli. Identification of this species is very difficult and requires considerable time. A PCR-based identification system using C. aerofaciens-specific primers is described. Using this PCR method, we identified 181 C. aerofaciens-like species isolated from human feces. These 181 strains were identified using the traditional method in past studies. Results of both methods matched. The direct detection method was performed using human feces samples from seven adults. Nested PCR was applied directly to the samples and all seven samples were positive. Quantification studies were performed using LightCycler?trade mark omitted?. The assay uses a double-stranded DNA dye to continuously monitor product formation and in a short time is able to quantify samples to 5 log units in concentration.     

Identification and quantitative analysis of beta-sitosterol oxides in vegetable oils by capillary gas chromatography-mass spectrometry

As vegetable oils and phytosterol-enriched spreads are marketed for frying food or cooking purposes, temperature is one of the most important factors leading to the formation of phytosterol oxides in food matrix. A methodology based on saponification, organic solvent extraction, solid-phase extraction (SPE), followed by mass spectrometric identification and quantitation of beta-sitosterol oxides using capillary gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode was developed and characterized. Relative response factors of six beta-sitosterol oxides, including 7alpha-hydroxy, 7beta-hydroxy, 5,6alpha-epoxy, 5,6beta-epoxy, 7-keto, and 5alpha,6beta-dihydroxysitosterol, were calculated against authentic standards of 19-hydroxycholesterol or cholestanol. Linear calibration data, limit of detection, and sample recoveries during analytical process. Recoveries of these oxidation compounds in spiked samples ranged from 88 to 115%, while relative standard derivation (R.S.D.) values were below 10% in most cases. The analytical method was applied to quantify beta-sitosterol oxides formed in thermal-oxidized vegetable oils which were heated at different temperatures and for varying time periods. Sitosterol oxidation is strikingly higher in sunflower oil relative to olive oil under all conditions of temperature and heating time.     

Challenges in mass spectrometry-based proteomics

During the last decade, protein analysis and proteomics have been established as new tools for understanding various biological problems. As the identification of proteins after classical separation techniques, such as two-dimensional gel electrophoresis, have become standard methods, new challenges arise in the field of proteomics. The development of "functional proteomics" combines functional characterization, like regulation, localization and modification, with the identification of proteins for deeper insight into cellular functions. Therefore, different mass spectrometric techniques for the analysis of post-translational modifications, such as phosphorylation and glycosylation, have been established as well as isolation and separation methods for the analysis of highly complex samples, e.g. protein complexes or cell organelles. Furthermore, quantification of protein levels within cells is becoming a focus of interest as mass spectrometric methods for relative or even absolute quantification have currently not been available. Protein or genome databases have been an essential part of protein identification up to now. Thus, de novo sequencing offers new possibilities in protein analytical studies of organisms not yet completely sequenced. The intention of this review is to provide a short overview about the current capabilities of protein analysis when addressing various biological problems.     

肿瘤患者皮纹特征的量化分类初步分析

本文对肿瘤患者的指纹和掌纹按照标准的分类方法进行了较为详细的分析,并与对照组进行了对比,用χ2检验的方法,发现患者与对照组之间在指纹和掌纹的出现率上均存在差异,这些结论为搭建量化皮纹特征模型、建立量化的皮纹特征指标体系、患者与对照组的分类判别都提供了有力的理论依据。     

Testing for genetically modified organisms (GMOs): Past, present and future perspectives

This paper presents an overview of GMO testing methodologies and how these have evolved and may evolve in the next decade. Challenges and limitations for the application of the test methods as well as to the interpretation of results produced with the methods are highlighted and discussed, bearing in mind the various interests and competences of the involved stakeholders. To better understand the suitability and limitations of detection methodologies the evolution of transformation processes for creation of GMOs is briefly reviewed.