SENSITIVITY TO PHOTOADDITION OF MONO-AND BIFUNCTIONAL FUROCOUMARINS OF X-RAY SENSITIVE MUTANTS OF SACCHAROMYCES CEREVISIAE

Abstract— With the exception of rad53 , seven other X-ray sensitive mutants of the rad50 serie of Saccharomyces cerevisiae were found to be more sensitive than the wild type to photoaddition of Afunctional (3-methoxypsoralen) and monofunctional (3-carbethoxypsoralen) furocoumarins. The magnitude of sensitivity to killing is dependent upon the locus and the phase of growth.
This means that in addition to the two repair pathways (excision-resynthesis and mutagenic pathways) previously shown to be involved in repair of furocoumarins photo-induced lesions, a third pathway is implicated in the repair of such lesions.     

The structure and energetics of pyrrolidinones, tetrahydrofuranones, piperidinones, and tetrahydropyranones: a computational study

We have performed high level ab initio quantum chemical calculations for 2- and 3-pyrrolidinone; tetrahydro-2- and -3-furanone; 2-, 3-, and 4-piperidinone; and tetrahydro-2-, -3-, and -4-pyranone. The most stable molecular structures were obtained from DFT calculations using the B3LYP density functional and the 6-31G(d) and 6-311+G(3df,2p) basis sets. The respective enthalpies of formation have been computed by the G3(MP2)//B3LYP composite method and appropriately chosen reactions. The calculated results are in excellent agreement with experimental data reported in the literature.     

Spektrophotometrische Bestimmung von Mikromengen Mangan mit Salicyl- und Acetylsalicylsäure

Zusammenfassung Eine spektrophotometrische Methode zur Bestimmung von Mangan in Submikrogrammengen wurde beschrieben. 1 bis 2,5 ml Probelösung werden mit 3 ml 0,58-m Salicylsäure oder Acetylsalicylsäure in 10%igem Ammoniak und 1 ml 5%igem Perhydrol versetzt. Nach 2 1/2 Stunden wird mit 10%igem Ammoniak auf 100 ml aufgefüllt und bei 385 nm spektrophotometrisch gemessen. Das Lambert-Beersche Gesetz wird für Konzentration von 0,005 bis 0,0125g/ml befolgt.

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Spectrophotometric determination of microamounts of manganese with salicylic and acetylsalicylic acid

Summary A method of spectrophotometric determination of Mn is described. 1 to 2.5 ml of the test solution was treated with 3 ml of 0.58-m solution of salicylic acid or acetylsalicylic acid in 10% amonia and 1 ml of 5% perhydrol are added. After 2 1/2 hours the volume is completed to 100 ml with 10% amonia. Extinction is measured at 385 nm. The law of Lambert-Beer is obeyed between 0.005g and 0.0125g/ml.

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Wir danken an dieser Stelle dem Banco Nacional de Desenvolvimento und dem Conselho Nacional de Pesquisas yon Brasilien, die uns diese Arbeiten erm6glicht haben.     

Quality assurance program for the chemical characterization of soils

A quality assurance program has been developed both to assess and to demonstrate the quality of the results produced by an analytical diagram applied to the chemical characterization of soils. The composition of several soils was determined following procedures based on the methods that are applied to silicate materials. A combination of acid decomposition followed by fusion allows the determination of SiO₂, Al, Fe, Ca, Mg, Ti, P, Mn, Cd, Co, Cr, Cu, Ni, Pb and Zn; a specific acid attack was used for Hg analysis and an acid mixture decomposition to analyse Na, K, Li and Sr. Several quality control parameters, namely calibration function characteristics, limits of detection, limits of quantification, quality control standards, duplicate analysis, spike recoveries and certified reference materials analysis, are introduced, evaluated and discussed. The results obtained for the certified reference materials show that the analytical diagram gave acceptable accurate values for the elements applying the quality assurance program proposed.     

Control of attachment of bovine serum albumin to pulse plasma-polymerized maleic anhydride by variation of pulse conditions

This letter describes how the irreversible attachment of bovine serum albumin (BSA) to films of plasma-polymerized maleic anhydride can be measured by an indirect antibody-binding assay and how this attachment appears to be strongly affected by the polymerization conditions. Surface plasmon resonance (SPR) was used to follow the binding of the antibody, anti-bovine serum albumin (aBSA), to protein-modified plasma-polymerized maleic anhydride films. It was found that BSA could be irreversibly bound to polymers made under pulse plasma conditions, but BSA did not bind to polymers made under continuous wave conditions. Moreover, the degree of antibody binding, which is directly related to the quantity of BSA on the polymer, correlated with the plasma duty cycle (t(on)/t(on) + t(off)): lower duty cycle pulse plasma conditions gave greater BSA attachment. We speculate that BSA is being covalently bound to the polymer via the reaction of amine groups on lysine residues in BSA with the retained anhydride group functionality in the polymer.     

The eukaryotic Pso2p/Snm1p family revisited: in silico analyses of Pso2p A, B and Plasmodium groups

The eukaryotic family of Pso2/Snm1 exo/endonuclease proteins has important functions in repair of DNA damages induced by chemical interstrand cross-linking agents and ionizing radiation. These exo/endonucleases are also necessary for V(D)J recombination and genomic caretaking. However, despite the growing biochemical data about this family, little is known about the number of orthologous/paralogous Pso2p/Snm1p sequences in eukaryotes and how they are phylogenetically organized. In this work we have characterized new Pso2p/Snm1p sequences from the finished and unfinished eukaryotic genomes and performed an in-depth phylogenetic analysis. The results indicate that four phylogenetically related groups compose the Pso2p/Snm1p family: (i) the Artemis/Artemis-like group, (ii) the Pso2p A group, (iii) the Pso2p B group and (iv) the Pso2p Plasmodium group. Using the available biochemical and genomic information about Pso2p/Snm1p family, we concentrate our research in the study of Pso2p A, B and Plasmodium groups. The phylogenetic results showed that A and B groups can be organized in specific subgroups with different functions in DNA metabolism. Moreover, we subjected selected Pso2p A, B and Plasmodium proteins to hydrophobic cluster analysis (HCA) in order to map and to compare conserved regions within these sequences. Four conserved regions could be detected by HCA, which are distributed along the metallo-β-lactamase and β-CASP motifs. Interestingly, both Pso2p A and B proteins are structurally similar, while Pso2p Plasmodium proteins have a unique domain organization. The possible functions of A, B and Plasmodium groups are discussed.     

Application of headspace-mass spectrometry for differentiating sources of olive oil

In the present work we propose the use of headspace-mass spectrometry (HS-MS) for the characterisation of monovarietal olive oils, an issue of interest when the origin of an oil has to be determined. The HS-MS procedure involves the direct introduction of the sample into a vial, headspace generation and automatic injection of the volatiles into a mass spectrometer. The results were compared with those obtained using more conventional approaches, including chromatographic, spectrophotometric and other types of analysis. Linear Discriminant Analysis (LDA) was applied to the data obtained with both analytical methodologies to achieve the differentiation of the three types of samples. The proposed method is faster and cheaper than those usually employed for edible oil analysis and no sample preparation is required. Additionally, the measuring process is simple and the results obtained from chemometric treatment are 100% correct as regards classification and prediction, making it an appropriate method for routine control.     

A new xanthone from Hedychium gardnerianum

A new xanthone (2), 3-(2-hydroxyethoxy)xanthone, and three known compounds, 1-hydroxyxanthone, salicylic acid and the sesquiterpene oplopanone, were isolated for the first time from the rhizomes of Hedychium gardnerianum Rosc. The structures of these compounds were elucidated on the basis of detailed spectral analysis, including 2D NMR experiments.     

Gold complexes with dithiothiophene ligands: a metal based on a neutral molecule

The gold complexes n-Bu4N[Au(alpha-tpdt)2] (5), n-Bu4N[Au(dtpdt)2] (4) and n-Bu4N[Au(tpdt)2] (6) based on new dithiothiophene ligands (alpha-tpdt= 2,3-thiophenedithiolate, dtpdt=2,3-dihydro-5,6-thiophenedithiolate and tpdt = 3,4-thiophenedithiolate) have been prepared and characterised. These gold(III) complexes are diamagnetic, but they can be oxidised with iodine to the paramagnetic compounds [Au(alpha-tpdt)2] (8), [Au(dtpdt)2] (7) and n-Bu4N[[Au(tpdt)2]n-2] (9), which were isolated as fine powders and which exhibit paramagnetic susceptibilities that are almost temperature independent with room temperature values of 2.5 x 10(-4), 2.0 x 10(-4) and 5 x 10(-4) emu x mol(-1), respectively. Interestingly, the neutral complex [Au(alpha-tpdt)2] (8) as a polycrystalline sample displays the properties of a metallic system with a room temperature electrical conductivity of 6 S x cm(-1) and a thermoelectric power of 5.5 microVK(-1); this is the first time that this metallic property has been observed in a molecular system based on a neutral species.