CHanalysis 2022 - Back to the Future of Analytical Excellence: Conference Report

ISSN:0009-429

Characterization of Lead–Phytochelatin Complexes by Nano-Electrospray Ionization Mass Spectrometry

The role of phytochelatins (PCn, metal-binding oligopeptides with the general structure (γGlu-Cys)n-Gly (n = 2–11) in metal detoxification is assumed to be based on immobilization of metals, which prevents binding of metals to important biomolecules. Although induction of phytochelatin synthesis has often been observed in algae upon exposure to metals, direct evidence for binding of the inducing metal to phytochelatins is scarce. In this study, a nano-electrospray ionization mass spectrometry (nano-ESI-MS) method is developed for identification and characterization of Pb(II)–PCn and Zn(II)–PCn complexes. Complexes of Pb(II) with standard PCn (n = 2–4; 0.25 mM Pb(II) and 0.5 mM PCn) were examined by nano-ESI-MS with respect to their stoichiometry. Pb–PCn mass spectra indicated the presence of the [M + H]+ peak of PCn and complexes with various stoichiometries. Analysis of Pb–PC2 allowed the identification of four different complexes observed at m/z 746.10, 952.06, 1285.24, and 1491.20, corresponding to [Pb–PC2]+, [Pb2–PC2]+, [Pb–(PC2)2]+, and [Pb2–(PC2)2]+. Their m/z indicated coordination of Pb(II) by PC2 through the thiol groups of PC cysteine and possibly carboxylic groups. For each of the standard PC3 and PC4, two different complexes were observed, corresponding to Pb–PC3, Pb2–PC3, Pb–PC4, and Pb2–PC4. The measured isotopic patterns were for all complexes identical to the theoretical isotopic patterns. Addition of Zn(II) (0.125–5 mM) to previously formed Pb–PC2 complexes showed the appearance of the [Zn–PC2]+ complexes at m/z 602.05 and the decrease of the [Pb–PC2]+ peak. These findings corroborate the postulated Pb–PC complexes from a previous study using size exclusion chromatography of PC extracted from algae, as well as the concurrent formation of Pb–, Zn–, and Cu–PC complexes in algae

Global proteomics analysis of testis and ovary in adult zebrafish ( Danio rerio )

The molecular mechanisms controlling sex determination and differentiation in zebrafish (Danio rerio) are largely unknown. A genome-wide analysis may provide comprehensive insights into the processes involved. The mRNA expression in zebrafish gonads has been fairly well studied, but much less data on the corresponding protein expression are available, although the proteins are considered to be more relevant markers of gene function. Because mRNA and protein abundances rarely correlate well, mRNA profiles need to be complemented with the information on protein expression. The work presented here analyzed the proteomes of adult zebrafish gonads by a multidimensional protein identification technology, generating the to-date most populated lists of proteins expressed in mature zebrafish gonads. The acquired proteomics data partially confirmed existing transcriptomics information for several genes, including several novel transcripts. However, disagreements between mRNA and protein abundances were often observed, further stressing the necessity to assess the expression on different levels before drawing conclusions on a certain gene's expression and function. Several gene groups expressed in a sexually dimorphic way in zebrafish gonads were identified. Their potential importance for gonad development and function is discussed. The data gained in the current study provide a basis for further work on elucidating processes occurring during zebrafish development with use of high-throughput proteomic

Characterization of a Novel Chemotactic Factor for Neutrophils in the Bronchial Secretions of Patients with Cystic Fibrosis

Chronic airway inflammation is a hallmark of cystic fibrosis (CF). Biological products with chemotactic activity are essential for neutrophil recruitment to sites of inflammation. The presence of a factor with chemotactic activity higher than that of interleukin (IL)-8 in the bronchial secretions of patients with CF has recently been reported. This article reports that the chemotactic activity of this factor remained unaffected by a variety of physical treatments and could be distinguished from those of IL-8, formylmethionylleucylphenylalanine, leukotreine B4, and platelet-activating factor. The factor induced chemotaxis and chemokinesis locomotion of neutrophils, and its chemotactic activity was sensitive to pertussis toxin and thapsigargin. Semipurified preparation of the chemotactic factor increased transiently intracellular Ca2+ concentration but failed to stimulate the release of neutrophil primary granules and the production of superoxide, suggesting that the semipurified chemotactic factor is a Ca2+-dependent chemoattractant of neutrophils, acting via pertussin toxin-sensitive G protein-coupled surface receptors, that directs neutrophil movement toward the airway epitheliu

Handling Very Large Platforms with the New SimGrid Platform Description Formalism

Simulation of parallel and distributed applications is a very active research field as simulation allows for repeatable results, makes it possible to explore various platform scenarios at will, is not as labor-intensive or as costly as running experiments on a real platform, and often makes it possible to run enormous numbers of experiments quickly. If many simulation toolkits exist, most of them face the issue of the description of the large scale platforms that are currently deployed. In this technical report we focus on the platform description format used by the SimGrid toolkit and present how we modify its DTD to tackle the scaling issues induced by large platforms. Experiments show a reduction by a 6,600 factor of the size of the XML file for a multi-cluster platform comprising 1,300 hosts. We also extend the existing DTD in order to integrate the description of other features like attaching arbitrary properties to resources or introducing randomness in the platform description and express the dynamic nature of a platform directly in the XML file

Amnesia Associated with Bilateral Hippocampal and Bilateral Basal Ganglia Lesions in Anoxia with Stimulant Use

We report a case of a 55-year-old man with ischemic lesions of the bilateral hippocampus and bilateral basal ganglia following a myocardial infarction during an episode of multiple drug use with subsequent anoxia requiring resuscitation. He presented for a neuropsychological evaluation with an anterograde amnesia for both explicit and procedural memory. There are two main points to this case, the unique aspects of the bilateral multifocal lesions and the functional, cognitive impact of these lesions. We hypothesize that his rare focal bilateral lesions of both the hippocampus and basal ganglia are a result of anoxia acting in synergy with his stimulant drug use (cocaine and/or 3,4-methylenedioxy-methamphetamine). Second, his unique lesions produced an explicit and implicit/procedural anterograde amnesia

Environmental Fate of Chiral Pollutants – the Necessity of Considering Stereochemistry

Many organic compounds regulated by environmental laws are chiral and are released into the environment as racemates. 3-Phenylbutanoic acid and mecoprop, two chiral pollutants, were enantioselectively degraded by pure cultures of microorganisms. This indicates the importance of assessing the environmental impact of stereoisomers separately, because selective enrichment of one of the enantiomers may occur in the environment. Field studies on the fate of highly polar, chiral compounds, like sulfophenylcarboxylates, are hampered by the lack of appropriate analytical methods for the separation of the enantiomers. Therefore, a method based on capillary electrophoresis with α-cyclodextrin as chiral selector was developed to separate the enantiomers of such compounds. In a field study at a Swiss waste disposal site, the fate of the chiral herbicide mecoprop was investigated. The enantiomeric ratio of (R)-mecoprop to (S)-mecoprop altered during groundwater passage of landfill leachate. This is a strong indication for in situ biodegradation. Our data imply that not only the enantiomers of a chiral drug or pesticide may exert different effects on the biological targets, but also their biodegradation and environmental fate may differ

Determination of Hydrophilic and Amphiphilic Organic Pollutants in the Aquatic Environment

Environmental chemists performing monitoring or process-oriented fate and behavior studies on organic micropollutants face the challenge of having to determine low concentrations of problem compounds in complex mixtures and difficult matrices, such as sewage sludge, surface and groundwater. Selective extraction and enrichment help to overcome sensitivity limitations and also to reduce the number of different species in the sample. A subsequent chromatographic separation step, together with analyte-specific detection, finally allows to identify and quantify single analytes in the presence of other organic material. This article describes a selection of analytical development work carried out at EAWAG for the determination of hydrophilic and amphiphilic organic pollutants in the aquatic environment