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Labelling Approach (labelling + approach)
Selected AbstractsTargeted comparative proteomics by liquid chromatography/matrix-assisted laser desorption/ionization triple-quadrupole mass spectrometry,RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 5 2006Jeremy E. Melanson Here we report the first application of a matrix-assisted laser desorption/ionization (MALDI) triple-quadrupole mass spectrometer for targeted proteomics. Employing an amine-specific isotopic labelling approach, the technique was validated using five randomly selected bovine serum albumin peptides differentially labelled at known ratios. An indirect benefit of the isotopic labelling technique is a significant enhancement of the a1 ion in tandem mass (MS/MS) spectra of all peptides studied. Therefore, the a1 ion was selected as the fragment ion for multiple reaction monitoring (MRM) in all cases, eliminating tedious method development and optimization. Accurate quantification was achieved with an average relative standard deviation (RSD) of 5% (n,=,5) and a detection limit of 14,amol. The technique was then applied to validate an important virulence biomarker of the fungal pathogen Candida albicans, which was not accurately quantified using global proteomics experiment employing two-dimensional liquid chromatography/electrospray ionization tandem mass spectrometry (2D-LC/ESI)-MS/MS. Using LC/MALDI-MRM analysis of five tryptic peptides, the protein PHR1 was found to be upregulated in the hyphal (pathogenic) form of C. albicans by a factor of 7.7,±,0.8. Copyright © 2006 John Wiley & Sons, Ltd. [source] Electron microscopy analysis of histone acetylation and DNA strand breaks in mouse elongating spermatids using a dual labelling approachANDROLOGIA, Issue 5 2010G. Bikond Nkoma Summary Chromatin remodelling steps in mammalian spermatids include post-translational modifications of histones and DNA fragmentation. Histone H4 hyperacetylation (AcH4) establishes a chromatin state that facilitates DNA repair in somatic cells. So we sought to determine whether a similar link exists in spermatids by combining immunogold labelling with detection of DNA strand breaks, making use of gold particles of different sizes. DNA strand breaks were not detected in the vicinity of AcH4 chromatin, suggesting that this modified histone may not be involved in the aetiology of DNA fragmentation and repair in spermatids. The AcH4 reactivity, however, indicates that chromatin remodelling is distributed throughout the nucleus. [source] Plant functional group identity influences short-term peatland ecosystem carbon flux: evidence from a plant removal experimentFUNCTIONAL ECOLOGY, Issue 2 2009Susan E. Ward Summary 1Northern hemisphere peatlands are globally important stores of organic soil carbon. We examined effects of plant functional group identity on short-term carbon (C) flux in an ombrotrophic peatland in northern England, UK, by selectively removing one of each of the three dominant plant functional groups (ericoid dwarf-shrubs, graminoids and bryophytes). Carbon dynamics were quantified by a combination of CO2 flux measurements and 13CO2 stable isotope pulse labelling approaches. 2Significant effects of plant functional group removals on CO2 fluxes and tracer 13C uptake and turnover were detected. Removal of ericoid dwarf-shrubs had the greatest influence on gross CO2 flux, increasing rates of respiration and photosynthesis by > 200% relative to the undisturbed control. After pulse labelling with 13CO2, we found that turnover of recent photosynthate, measured as respired 13CO2, was also greatest in the absence of dwarf-shrubs. 3Analysis of 13C tracer enrichment in leaf tissues from all plant removal treatments showed that the rate of fixation of 13CO2 and turnover of 13C labelled photosynthate in leaf tissue was greatest in graminoids and lowest in bryophytes. Furthermore, graminoid leaf 13C enrichment was greatest when growing in the absence of dwarf-shrubs, suggesting that the presence of dwarf-shrubs reduced the photosynthetic activity of graminoids. 4We conclude that plant functional groups differentially influence the uptake and short-term flux of carbon in peatlands, suggesting that changes in the functional composition of vegetation resulting from global change have the potential to alter short-term patterns of carbon exchange in peatland. [source] Convenient and efficient deuteration of functionalized aromatics with deuterium oxide: catalysis by cycloocta-1,5-dienyliridium(I) 1,3-dionatesJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 13 2003B. McAuley Abstract Aromatic compounds bearing an ortho -directing substituent may be deuterated by exchange with deuterium oxide in the presence of a range of cycloocta-1,5-dienyliridium(I)1,3-dionate catalysts. The exchange takes place in several dipolar aprotic solvents and is directly applicable to the deuteration of polar compounds. Isotope incorporation is efficient and regiospecific. The method is applicable to a wide range of ortho -directing groups some of which are only weak directors for alternative ortho -labelling approaches. In addition, the application of microwaves enables labelling within minutes even with sub-stituents which are poor directors. Copyright © 2003 John Wiley & Sons, Ltd. [source] | ||||||||||