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Selected AbstractsSmall heat shock protein Hsp27 prevents heat-induced aggregation of F-actin by forming soluble complexes with denatured actinFEBS JOURNAL, Issue 22 2007Anastasia V. Pivovarova Previously, we have shown that the small heat shock protein with apparent molecular mass 27 kDa (Hsp27) does not affect the thermal unfolding of F-actin, but effectively prevents aggregation of thermally denatured F-actin [Pivovarova AV, Mikhailova VV, Chernik IS, Chebotareva NA, Levitsky DI & Gusev NB (2005) Biochem Biophys Res Commun331, 1548,1553], and supposed that Hsp27 prevents heat-induced aggregation of F-actin by forming soluble complexes with denatured actin. In the present work, we applied dynamic light scattering, analytical ultracentrifugation and size exclusion chromatography to examine the properties of complexes formed by denatured actin with a recombinant human Hsp27 mutant (Hsp27,3D) mimicking the naturally occurring phosphorylation of this protein at Ser15, Ser78, and Ser82. Our results show that formation of these complexes occurs upon heating and accompanies the F-actin thermal denaturation. All the methods show that the size of actin,Hsp27-3D complexes decreases with increasing Hsp27-3D concentration in the incubation mixture and that saturation occurs at approximately equimolar concentrations of Hsp27-3D and actin. Under these conditions, the complexes exhibit a hydrodynamic radius of ,,16 nm, a sedimentation coefficient of 17,20 S, and a molecular mass of about 2 MDa. It is supposed that Hsp27-3D binds to denatured actin monomers or short oligomers dissociated from actin filaments upon heating and protects them from aggregation by forming relatively small and highly soluble complexes. This mechanism might explain how small heat shock proteins prevent aggregation of denatured actin and by this means protect the cytoskeleton and the whole cell from damage caused by accumulation of large insoluble aggregates under heat shock conditions. [source] Synthesis and Conformational Analysis of Pentapeptides Containing Enantiomerically Pure 2,2-Disubstituted GlycinesHELVETICA CHIMICA ACTA, Issue 3 2008Kathrin Abstract The synthesis and conformational analysis of model pentapeptides with the sequence Z-Leu-Aib-Xaa-Gln-Valol is described. These peptides contain two 2,2-disubstituted glycines (,,, -disubstituted , -amino acids), i.e., Aib (aminoisobutyric acid), and a series of unsymmetrically substituted, enantiomerically pure amino acids Xaa. These disubstituted amino acids were incorporated into the model peptides via the ,azirine/oxazolone method'. Conformational analysis was performed in solution by means of NMR techniques and, in the solid state, by X-ray crystallography. Both methods show that the backbones of these model peptides adopt helical conformations, as expected for 2,2-disubstitued glycine-containing peptides. [source] Seasonal modulation of the El Niño,southern oscillation relationship with sea level pressure anomalies over the North Atlantic in October,March 1873,1996INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 2 2003V. Moron Abstract The seasonal modulation of the relationship between the sea-level pressure anomalies (SLPAs) over the North Atlantic region (100°W,50°E; 20,70°N) and the sea surface temperature anomalies (SSTAs) in the tropical Pacific (120,290°E; 20°N,20°S) is investigated in the northern winter (October to March) from 1873 to 1996, using singular-value decomposition and composite analyses. Both methods show that the pattern of the North Atlantic SLPA associated with the tropical Pacific SSTA in November,December is different from that found in January,March. The surface covered by a significant SLPA is larger in November,December and February,March than in January. In November,December, the warm El Niño,southern oscillation (ENSO) events are associated with negative SLPAs extending from the Hudson Bay to Scandinavia and positive SLPAs over the Azores high. The cold ENSO events are associated with a positive SLPA between Greenland and western Europe. In January, and mainly in February,March, the warm ENSO events are associated with a positive SLPA north of 50°N and a negative SLPA extending from the southeastern USA toward western and central Europe. The cold ENSO events exhibit almost reversed SLPA patterns. The change between November,December and January,March is also observed at the hemispheric scale. In November,December, the SLPAs associated with the warm minus cold ENSO composite form a hemispheric north,south dipole pattern with positive (negative) anomalies south (north) of 40,45°N. In January,March, the SLPA pattern associated with the warm minus cold ENSO composite is close to the tropical Northern-Hemisphere pattern. Copyright © 2003 Royal Meteorological Society. [source] Wage differentials between the public and private sectors in India,JOURNAL OF INTERNATIONAL DEVELOPMENT, Issue 3 2007Elena Glinskaya Abstract This study uses 1993,94 and 1999,2000 rounds of India Employment and Unemployment survey to investigate wage differentials between the public and private sectors. To obtain robust estimates of the wage differential, we apply three econometric techniques each relying on a different set of assumptions about the process of job selection and wage formation. All three methods show that differences in wages between public sector workers and workers in the formal-private and informal-casual sectors are positive and high. On average, the public sector premium ranges between 62 and 102 per,cent over the private-formal sector, and between 164 and 259 per,cent over the informal-casual sector, depending on the choice of methodology. The wage differentials in India tend to be higher in rural as compared to urban areas, and are higher among women than among men. The wage differential also tends to be higher for low-skilled workers. There is considerable evidence of an increase in the wage differential between 1993,1994 and 1999,2000. Copyright © 2007 John Wiley & Sons, Ltd. [source] STOCHASTIC WATER QUALITY ANALYSIS USING RELIABILITY METHOD,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 3 2001Kun-Yeun Han ABSTRACT: This study developed a QUAL2E-Reliability Analysis (QUAL2E-RA) model for the stochastic water quality analysis of the downstream reach of the main Han River in Korea. The proposed model is based on the QUAL2E model and incorporates the Advanced First-Order Second-Moment (AFOSM) and Mean-Value First-Order Second-Moment (MFOSM) methods. After the hydraulic characteristics from standard step method are identified, the optimal reaction coefficients are then estimated using the Broyden-Fletcher-Goldfarb-Shanno (BFGS) method. Considering variations in river discharges, pollutant loads from tributaries, and reaction coefficients, the violation probabilities of existing water quality standards at several locations in the river were computed from the AFOSM and MFOSM methods, and the results were compared with those from the Monte Carlo method. The statistics of the three uncertainty analysis methods show that the outputs from the AFOSM and MFOSM methods are similar to those from the Monte Carlo method. From a practical model selection perspective, the MFOSM method is more attractive in terms of its computational simplicity and execution time. [source] Structural defects in homoepitaxial diamond layers grown on off-axis Ib HPHT substratesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 12 2006T. Bauer Abstract In the present study homoepitaxial diamond films have been grown by microwave plasma chemical vapour deposition (MWPCVD) on (001)-oriented Ib HPHT substrates with off-axis angles of up to 11°. Freestanding films of several hundred microns thickness were produced by removal of the Ib substrate and of the polycrystalline rim. In high resolution X-ray diffraction (HRXRD) rocking curve measurements the crystals showed a full width at half maximum (FWHM) between (2 × 10,3)°, which is close to the instrumental limit of our setup, and maximum values of (3 × 10,2)°. The structural quality is directly reflected in the strength of the birefringence observed in the optical microscope. While the high quality sample showed a weak birefringence with a couple of localized centres distributed over the whole sample surface, a tatami-like pattern is measured for the sample with the broad rocking curve. Identical defect structures with perfect correspondence are observed in X-ray topography images. Furthermore the X-ray topographs allow to identify isolated dislocation lines. Both characterisation methods show that the defect lines are aligned along the off-axis direction which allows conclusions on the mechanism of formation. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Carbon Nanorings: A Challenge to Theoretical ChemistryCHEMPHYSCHEM, Issue 12 2006I. García Cuesta Dr. Abstract High-level quantum-chemical methods show that the binding in the inclusion complex of hexamethylbenzene (HMB) in 6-cycloparaphenilacetylene (6-CPPA) cannot be explained only in terms of electrostatic interactions,caused by the polarization associated to curved ,-conjugated systems,and the inclusion of dispersion forces is definitely needed. The theoretical description of van der Waals interactions is notoriously complicated and in fact some DFT methods cannot even predict the existence of the relatively small supramolecular nanoring studied here. However, ab initio MP2 calculations agree with experimental data and show that, in the considered complex, the HMB fragment is placed at the center of the 6-CPPA ring. The binding energy, which is not available experimentally, is calculated to be around ,14 kcal,mol,1 with a lower limit of ,19 kcal,mol,1. [source] | ||||||||||