Structural Organizations of Qß and MS2 Phages Affect Capsid Protein Modifications by Oxidants Hypochlorous Acid and Peroxynitrite.

Pathogenic enteric viruses and bacteriophages such as Qß and MS2 are transmitted through the fecal-oral route. However, oxidants such as peroxynitrite (ONOOH) and hypochlorous acid (HClO) can prevent new infection by inactivating infectious viruses. Their virucidal effect is well recognized, and yet predicting the effects of oxidants on viruses is currently impossible because the detailed mechanisms of viral inactivation remain unclear. Our data show that ONOOH and HClO cross-linked the capsid proteins and RNA genomes of Qß and MS2 phages. Consistently, the capsids appeared intact by transmission electron microscopy (TEM) even when 99% of the phages were inactivated by oxidation. Moreover, a precise molecular study of the capsid proteins shows that ONOOH and HClO preferentially targeted capsid protein regions containing the oxidant-sensitive amino acid C, Y, or W. Interestingly, the interaction of these amino acids was a crucial parameter defining whether they would be modified by the addition of O, Cl, or NO2 or whether it induced the loss of the protein region detected by mass spectrometry, together suggesting potential sites for cross-link formation. Together, these data show that HClO and ONOOH consistently target oxidant-sensitive amino acids regardless of the structural organization of Qß and MS2, even though the phenotypes change as a function of the interaction with adjacent proteins/RNA. These data also indicate a potential novel mechanism of viral inactivation in which cross-linking may impair infectivity.

Increased synthesis of a new oleanane-type saponin in hairy roots of marigold (Calendula officinalis) after treatment with jasmonic acid.

Native plant of marigold (Calendula officinalis L.) synthesizes oleanolic acid saponins classified as glucosides or glucuronides according to the first residue in sugar chain bound to C-3 hydroxyl group. Hairy root culture, obtained by transformation with Agrobacterium rhizogenes strain 15834, exhibit a potent ability of synthesis of oleanolic acid glycosides. The HPLC profile of saponin fraction obtained from C. officinalis hairy roots treated with plant stress hormone, jasmonic acid, showed the 10-times increase of the content of one particular compound, determined by NMR and MALDI TOF as a new bisdesmoside saponin, 3-O-ß-d-glucuronopyranosyl-28-O-ß-d-galactopyranosyl-oleanolic acid. Such a diglycoside does not occur in native C. officinalis plant. It is a glucuronide, whereas in the native plant glucuronides are mainly accumulated in flowers, while glucosides are the most abundant saponins in roots. Thus, our results revealed that the pathways of saponin biosynthesis, particularly reactions of glycosylation, are altered in C. officinalis hairy root culture.

A new method to analyze copolymer based superplasticizer traces in cement leachates.

Enhancing the flowing properties of fresh concrete is a crucial step for cement based materials users. This is done by adding polymeric admixtures. Such additives have enabled to improve final mechanicals properties and the development of new materials like high performance or self compacting concrete. Like this, the superplasticizers are used in almost cement based materials, in particular for concrete structures that can have a potential interaction with drinking water. It is then essential to have suitable detection techniques to assess whether these organic compounds are dissolved in water after a leaching process or not. The main constituent of the last generation superplasticizer is a PolyCarboxylate-Ester copolymer (PCE), in addition this organic admixture contains polyethylene oxide (free PEO) which constitutes a synthesis residue. Numerous analytical methods are available to characterize superplasticizer content. Although these techniques work well, they do not bring suitable detection threshold to analyze superplasticizer traces in solution with high mineral content such as leachates of hardened cement based materials formulated with superplasticizers. Moreover those techniques do not enable to distinguish free PEO from PCE in the superplasticizer. Here we discuss two highly sensitive analytical methods based on mass spectrometry suitable to perform a rapid detection of superplasticizer compounds traces in CEM I cement paste leachates: MALDI-TOF mass spectrometry, is used to determine the free PEO content in the leachate. However, industrial copolymers (such as PCE) are characterized by high molecular weight and polymolecular index. These two parameters lead to limitation concerning analysis of copolymers by MALDI-TOFMS. In this study, we demonstrate how pyrolysis and a Thermally assisted Hydrolysis/Methylation coupled with a triple-quadrupole mass spectrometer, provides good results for the detection of PCE copolymer traces in CEM I cement paste leachates.

Post-source decay of alkylated and functionalized polycyclic aromatic compounds.

Post-source decay (PSD) is a valuable tool for providing structural information from large molecules by time-of-flight mass spectrometry (TOFMS). We used PSD to obtain this type of data from small molecules in the laser desorption/ionization (LDI) study of diesel engine exhaust particles. As the original nitrogen laser (lambda = 337 nm, E = 3.5 eV/photon) of our TOF mass spectrometer does not yield sufficient energy to ionize polycyclic aromatic hydrocarbons (PAHs), a second laser with a shorter wavelength has been coupled to the instrument. The fourth harmonic of a Nd:YAG laser (lambda = 266 nm, 4.6 eV/photon) has been chosen to achieve two-photon single-step desorption/ionization of PAHs. The PSD fragmentation of functionalized, alkylated and sulfur PAHs is discussed. Diesel engine exhaust particles are also studied as an example of a real complex sample. This technique is presented herein as a way to identify small molecules in environmental samples. Information provided by LDI-PSD-TOFMS can be a way to distinguish pollutants with very close molecular weights even if the resolving power of a TOF mass spectrometer is not sufficient.

Potential of laser ablation and laser desorption mass spectrometry to characterize organic and inorganic environmental pollutants on dust particles.

Stainless steel factories are known to release particles into the atmosphere. Such particulate matter contains significant amounts of heavy metals or toxic inorganic compounds and organic pollutants such as, for example, Cr(VI) and polycyclic aromatic hydrocarbons (PAHs). The investigation of Cr(VI) and PAHs is often complicated by the associated matrix. Organic and inorganic pollutants present in stainless steel dust particles have been investigated with the same laser microprobe mass spectrometer according to two original methodologies. These analytical methods do not require time-consuming pretreatment (extraction, solubilization) or preconcentration steps. More specifically, experiments are conducted with a Fourier transform ion cyclotron resonance mass spectrometer coupled to an ArF (193 nm) or a tripled frequency Nd-YAG (355 nm) laser. Experiments at 355 nm allow the nature of the most frequently occurring Cr(III)/Cr(VI) compounds in dust particles to be identified. Examination of PAHs at 193 nm is assisted by the formation of pi-complexes with 7,7',8,8'-tetracyanoquinodimethane to prevent their evaporation in the mass spectrometer during analysis and to ensure an increase in sensitivity.

Laser desorption/ionization mass spectrometry of diesel particulate matter with charge-transfer complexes.

Polycyclic aromatic hydrocarbons (PAHs) are often associated with complex matrixes such as exhaust diesel particulate matter (DPM), which complicates their study. In that case, laser desorption/ionization mass spectrometry is one of the techniques which ensures their direct analysis in the solid state. We demonstrate in this paper that the use of charge-transfer pi-complexing agents allows us to selectively detect by Fourier transform ion cyclotron resonance mass spectrometry PAHs adsorbed on diesel particles with high sensitivity. 2,4,7-trinitro-9-fluorenone and 7,7',8,8'-tetracyanoquinodimethane pi-acceptor compounds form charge-transfer complexes with PAHs and prevent their evaporation in the mass spectrometer during analysis. Moreover, the production of PAH molecular ions is dramatically increased by laser irradiation of these complexes at short wavelength (221.7 nm) and low power density (5 x 10(6) W cm(-)(2)). This methodology is applied for the first time to the examination of DPM collected during the new European driving cycle for light-duty vehicles. Differentiation criteria may coherently be assigned to engine operating mode (engine temperature, driving conditions). DPM samples can also be easily distinguished in negative ions according to the high sensitivity of this detection mode to sulfate compounds.