Home About us Contact
|
Home About us Contact | ||
|
|
||
Significant Peaks (significant + peak)
Selected AbstractsMolecular mass of macromolecules and subunits and the quaternary structure of hemoglobin from the microcrustacean Daphnia magnaFEBS JOURNAL, Issue 14 2006Tobias Lamkemeyer The molecular masses of macromolecules and subunits of the extracellular hemoglobin from the fresh-water crustacean Daphnia magna were determined by analytical ultracentrifugation, multiangle laser light scattering and electrospray ionization mass spectrometry. The hemoglobins from hypoxia-incubated, hemoglobin-rich and normoxia-incubated, hemoglobin-poor Daphnia magna were analyzed separately. The sedimentation coefficient of the macromolecule was 17.4 ± 0.1 S, and its molecular mass was 583 kDa (hemoglobin-rich animals) determined by AUC and 590.4 ± 11.1 kDa (hemoglobin-rich animals) and 597.5 ± 49 kDa (hemoglobin-poor animals), respectively, determined by multiangle laser light scattering. Measurements of the hemoglobin subunit mass of hemoglobin-rich animals by electrospray ionization mass spectrometry revealed a significant peak at 36.482 ± 0.0015 kDa, i.e. 37.715 kDa including two heme groups. The hemoglobin subunits are modified by O-linked glycosylation in the pre-A segments of domains 1. No evidence for phosphorylation of hemoglobin subunits was found. The subunit migration behavior during SDS/PAGE was shown to be influenced by the buffer system used (Tris versus phosphate). The subunit mass heterogeneity found using Tris buffering can be explained by glycosylation of hemoglobin subunits. Based on molecular mass information, Daphnia magna hemoglobin is demonstrated to consist of 16 subunits. The quaternary structure of the Daphnia magna hemoglobin macromolecule was assessed by three-dimensional reconstructions via single-particle analysis based on negatively stained electron microscopic specimens. It turned out to be much more complex than hitherto proposed: it displays D4 symmetry with a diameter of approximately 12 nm and a height of about 8 nm. [source] The utility of immature reticulocyte fraction as an indicator of erythropoietic response to altitude training in elite cyclistsINTERNATIONAL JOURNAL OF LABORATORY HEMATOLOGY, Issue 1p2 2010V. S. NADARAJAN Summary Altitude training is sometimes employed by elite endurance athletes to improve their sea level performance. This improvement results from the increased red cell mass consequent upon the boost in erythropoietin (EPO) level that occurs as a response to the relatively hypoxic environment at high altitudes. We measured serum EPO levels together with various red cell and reticulocyte parameters including immature reticulocyte fraction (IRF) in eight national track-endurance cyclists, resident at sea-level, prior to and upon return from an altitude of approximately 1905 m. Reticulocytes and soluble transferrin receptor (sTfR) were significantly increased with reduction in ferritin levels immediately on return from high altitude indicating increased erythropoietic activity. IRF in particular showed a significant peak immediately on return but decline to sub-baseline levels by day 9, and recovery to baseline by day 16. Our results indicate that IRF is a sensitive marker of erythropoietic status in athletes undergoing altitude training and subsequent loss of EPO stimuli on return to sea level. [source] Sensing of toxic metals through pH changes using a hybrid sorbent material: Concept and experimental validationAICHE JOURNAL, Issue 11 2009Prasun K. Chatterjee Abstract This article reports a new hybrid sorbent material that is capable of detecting trace concentration of toxic metals, such as zinc, lead, copper, nickel, etc., through pH changes only. The material is essentially a composite granular material synthesized through rapid fusion of a mixture of amorphous hydrated ferric oxide (HFO) and akermanite or calcium magnesium silicate (Ca2MgSi2O7). When a water sample is rapidly passed through a mini-column containing this hybrid material, effluent pH at the exit always remains alkaline (,9.0) because of slow hydrolysis of akermanite and steady release of hydroxyl (OH,) ions. This exit solution turns pink through the addition of a phenolphthalein indicator. Commonly encountered electrolytes containing sodium, calcium, chloride, and sulfate have no impact on the exit pH from the mini-column. However, when trace concentration of a heavy metal (say lead) is present in the sample water, a considerable drop in pH (>2 units) is observed for the exiting solution. At this point, the solution turns colorless through the addition of a phenolphthalein indicator. Moreover, the change in the slope of pH, i.e., ,dpH/dBV, provides a sharp, noticeable peak for each toxic metal where BV is the bed volumes of solution fed. The technique allowed detection of zinc and lead through pH swings in synthesized samples, spiked Bethlehem City water, and also in Lehigh River water in the presence of phosphate and natural organic matter (NOM). Using a simple preconcentration technique, lower than 10 ,g/l of lead was detected with a significant peak. From a mechanistic viewpoint, high sorption affinity of HFO surface sites toward toxic metal cations, ability of akermanite to maintain near-constant alkaline pH for a prolonged period through slow hydrolysis and labile metal-hydroxy complex formation causing dissipation of OH, ions from the aqueous phase provide a synergy that allows detection of toxic metals at concentrations well below 100 ,g/l through pH changes. Nearly all previous investigations pertaining to toxic metals sensing use metal-selective enzymes or organic chromophores. This simple-to-operate technique using an inexpensive hybrid material may find widespread applications in the developing world for rapid detection of toxic metals through pH changes. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] UV-A/BLUE LIGHT,INDUCED REACTIVATION OF SPORE GERMINATION IN UV-B IRRADIATED ULVA PERTUSA (CHLOROPHYTA),JOURNAL OF PHYCOLOGY, Issue 2 2004Taejun Han Recent reduction in the ozone shield due to manufactured chlorofluorocarbons raised considerable interest in the ecological and physiological consequences of UV-B radiation (,=280,315 nm) in macroalgae. However, early life stages of macroalgae have received little attention in regard to their UV-B sensitivity and UV-B defensive mechanisms. Germination of UV-B irradiated spores of the intertidal green alga Ulva pertusa Kjellman was significantly lower than in unexposed controls, and the degree of reduction correlated with the UV doses. After exposure to moderate levels of UV-B irradiation, subsequent exposure to visible light caused differential germination in an irradiance- and wavelength-dependent manner. Significantly higher germination was found at higher photon irradiances and in blue light compared with white and red light. The action spectrum for photoreactivation of germination in UV-B irradiated U. pertusa spores shows a major peak at 435 nm with a smaller but significant peak at 385 nm. When exposed to December sunlight, the germination percentage of U. pertusa spores exposed to 1 h of solar radiation reached 100% regardless of the irradiation treatment conditions. After a 2-h exposure to sunlight, however, there was complete inhibition of germination in PAR+UV-A+UV-B in contrast to 100% germination in PAR or PAR+UV-A. In addition to mat-forming characteristics that would act as a selective UV-B filter for settled spores under the parental canopy, light-driven repair of germination after UV-B exposure could explain successful continuation of U. pertusa spore germination in intertidal settings possibly affected by intense solar UV-B radiation. [source] Extracting star formation histories from medium-resolution galaxy spectraMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2006H. Mathis ABSTRACT We adapt an existing data compression algorithm, moped, to the extraction of median-likelihood star formation histories from medium-resolution galaxy spectra. By focusing on the high-pass components of galaxy spectra, we minimize potential uncertainties arising from the spectrophotometric calibration and intrinsic attenuation by dust. We validate our approach using model high-pass spectra of galaxies with different star formation histories covering the wavelength range 3650,8500 Å at a resolving power of ,2000. We show that the method can recover the full star formation histories of these models, without prior knowledge of the metallicity, to within an accuracy that depends sensitively on the signal-to-noise ratio. The investigation of the sensitivity of the flux at each wavelength to the mass fraction of stars of different ages allows us to identify new age-sensitive features in galaxy spectra. We also highlight a fundamental limitation in the recovery of the star formation histories of galaxies for which the optical signatures of intermediate-age stars are masked by those of younger and older stars. As an example of application, we use this method to derive average star formation histories from the highest-quality spectra of typical (in terms of their stellar mass), morphologically identified early- and late-type galaxies in the Early Data Release (EDR) of the Sloan Digital Sky Survey (SDSS). We find that, in agreement with the common expectation, early-type galaxies must have formed most of their stars over 8 Gyr ago, although a small fraction of the total stellar mass of these galaxies may be accounted for by stars with ages down to 4 Gyr. In contrast, late-type galaxies appear to have formed stars at a roughly constant rate. We also investigate the constraints set by the high-pass signal in the stacked spectra of a magnitude-limited sample of 20 623 SDSS-EDR galaxies on the global star formation history of the Universe and its distribution among galaxies in different mass ranges. We confirm that the stellar populations in the most massive galaxies today appear to have formed on average earlier than those in the least massive galaxies. Our results do not support the recent suggestion of a statistically significant peak in the star formation activity of the Universe at redshifts below unity, although such a peak is not ruled out. [source] Lipid analysis of the sex pheromone gland of the moth Heliothis virescensARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 2 2005S.P. Foster Abstract The sex pheromone gland of female Heliothis virescens was analyzed for fatty acid and lipid content. Base methanolysis of the gland showed a large amount of methyl (Z)-11-hexadecenoate (Z11-16:Acyl), the fatty acyl analog of the major pheromone component, (Z)-11-hexadecenal, as well as a small amount of methyl (Z)-11-octadecenoate. Methyl esters of various common fatty acids were also observed. HPTLC analysis of the glandular lipids revealed large quantities of triacylglycerols (TGs), and lesser amounts of 1,2-diacylglycerols (1,2-DGs), 2- monoacylglycerols (2-MGs), phosphatidyl ethanolamines, and phosphatidyl cholines. The greatest amount of Z11-16:Acyl in these lipids was in the TGs, with lesser amounts in the two phospholipid classes and only trace amounts in the other neutral lipids. The glands of females at various ages and photoperiodic times were extracted, fractionated into neutral and polar fractions by silica SPE, and fatty acid titers in these fractions determined. All fatty acids, but notably Z11-16:Acyl, showed significant total and neutral lipid fraction peaks at mid scotophase for 2-day-old females; a less dramatic, but significant, Z11-16:Acyl peak in the polar fraction was also observed. However, only a relatively small proportion (<50%) of this acid was recovered from the silica at all times. This "non-recoverable" Z11-16:Acyl showed a dramatic and significant peak at mid scotophase for 2-day females, corresponding roughly with maximal pheromone titer. All other acids in the gland were recovered in high proportions, and their respective "non-recoverable" titers were not different at any of the times analyzed. Based on previous work, this non-recoverable Z11-16:Acyl is likely the CoA ester. Therefore, it appears that the pheromone gland of H. virescens maintains pools of Z11-16:Acyl in both CoA ester and TG forms, which are available for biosynthesis of pheromone. These pools are greatest during maximal pheromone production when the biosynthetic enzymes, possibly the fatty acid reductase, are unable to utilize rapidly enough the quantities of Z11-16:Acyl biosynthesized. Arch. Insect Biochem. Physiol. 59:80,90, 2005. © 2005 Wiley-Liss, Inc. [source] Serial monitoring of immunological parameters following human hand transplantCLINICAL TRANSPLANTATION, Issue 2 2004Xiao-Fei Zheng Abstract:, Background:, Although early successes have been achieved in human hand transplant, the changes of immunological parameters in the recipients and their relations to clinical events were not yet known. Methods:, In two patients undergoing hand transplantation, we prospectively determined lymphocyte subsets using flow cytometry as well as the serum levels of interleukin (IL)-2, IL-10, tumor necrosis factor (TNF)- ,, and interferon (IFN)- , using enzyme linked immunosorbent assays during the first 6 months after transplantation. Results:, The decreases in CD, CD, CD T cell, the activated T cell (CD/CD, CD/HLA-DR+) as well as IL-2, IFN- , and corresponding significant peak in IL-10 in human hand transplant during the first post-transplant week were observed. Then these parameters recovered to the pre-transplant level except for an even higher level of CD T cell. The low CD/CD ratio was been maintained constantly. After 7 wk, IL-2, IFN- ,, and IL-10 decreased to be maintained at a low or undetectable level except for slight increase in IL-10 at post-transplant month 5. There are no significant variation in TNF- , early after transplant. After 3 months, IL-10 was not detected again. Conclusion:, The immunosuppressive agents had significantly effects on the immunological status in human hand transplant recipients. These profiles of immunological parameters would be useful data for the future immunomonitoring in human hand transplant recipients. [source] Modulation of the intraseasonal rainfall over tropical Brazil by the Madden,Julian oscillationINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 13 2006Everaldo B. De Souza Abstract Fifteen years (1987,2001) of rain gauge-based data are used to describe the intraseasonal rainfall variability over tropical Brazil and its associated dynamical structure. Wavelet analysis performed on rainfall time series showed significant peaks centered roughly in periods of 30,70 days, particularly in the eastern southeastern Amazon and northern northeast Brazil. A significant enhancement of precipitation with maximum anomalies in a northeastward oriented band over tropical Brazil is evidenced from empirical orthogonal function (EOF) analysis of 30,70-day filtered rainfall anomalies during rainy season (January to May). Lagged/lead composites revealed that, on a global scale, the Madden,Julian oscillation (MJO) is the main atmospheric-mechanism modulator of the pluviometric variations on intraseasonal timescale in the eastern Amazon and northeast Brazil. A coherent northward expansion of rainfall across tropical Brazil is evident during the passage of MJO over South America. Regionally, the establishment of a quasi-stationary deep convection band triggered by the simultaneous manifestation of south Atlantic convergence zone (SACZ) and intertropical convergence zone (ITCZ) explains the intensified rainfall over these regions. Such regional mechanisms are dynamically embedded within the eastward-propagating MJO-related large-scale convective envelope along tropical South America/the Atlantic Ocean. These features occur in association with a significant intraseasonal evolution of the lower-level wind and sea-surface temperature (SST) patterns, particularly in the Atlantic Ocean, including a coherent dynamical connection with atmospheric circulation, deep convective activity over South America and rainfall over tropical Brazil. Copyright © 2006 Royal Meteorological Society [source] Incidence and characteristics of endemic Norwalk-like virus-associated gastroenteritisJOURNAL OF MEDICAL VIROLOGY, Issue 4 2003John A. Marshall Abstract Endemic gastroenteritis associated with the Norwalk-like viruses (NLVs) is little understood. This study tested for NLV in gastroenteritis cases in 257 households in Melbourne, Australia, for the period September 1997 to February 1999 by a reverse transcription hemi-nested polymerase chain reaction. Positive samples were studied by nucleotide sequencing and phylogenetic analysis. NLV was detected in 73 (11.4%) of 638 faecal specimens tested. Twelve (1.9%) were NLV genogroup 1 (G1) and 61 (9.6%) NLV genogroup 2 (G2). Gastroenteritis symptoms associated with NLV G2/no other pathogens were significantly more severe than where no NLV was detected. NLV G1 and NLV G2 were detected in adults and children, males and females. NLV G2 incidence showed a marked seasonal periodicity with significant peaks in the Australian late spring/early summer periods. NLV G1 seasonality was significantly different from that of NLV G2. Seven major NLV clusters were identified by phylogenetic analysis. J. Med. Virol. 69:568,578, 2003. © 2003 Wiley-Liss, Inc. [source] Effect of density homogeneity on the dynamic response of powder bedsAICHE JOURNAL, Issue 8 2003T. Yanagida Homogeneous and inhomogeneous powder beds subjected to low-magnitude vibration are compared in terms of the dynamic response. The inhomogeneous samples were segregated into two phases: loose and dense phases, layering the two phases horizontally or vertically. An apparent mass, defined as a ratio of the base force to base acceleration, was measured. Comparison of homogeneous and segregated data demonstrated a significant density gradient dependence on the apparent mass data. First, homogeneous systems showed a resonant peak, which gave the longitudinal elastic modulus of the bed via the velocity of longitudinal stress wave propagation. Second, vertically segregated systems exhibited two significant peaks at low frequencies, corresponding to the resonance of each phase. In addition, the apparent mass values at the two peaks were related to the quantity of each phase. Third, horizontally segregated systems exhibited a resonant peak, whose frequency was approximately equal to homogeneous data, but the apparent mass value at the peak differed from homogeneous data. A model based on the fourth-power scaling law, two-phase theory and Rayleigh's energy method gave an interpretation for the insensitivity of the peak frequency to the density gradient in the vertical direction. [source] Bioimaging TOF-SIMS of tissues by gold ion bombardment of a silver-coated thin sectionMICROSCOPY RESEARCH AND TECHNIQUE, Issue 6 2004Håkan Nygren Abstract The imaging time-of-flight secondary-ion-mass-spectrometry (TOF-SIMS) method was utilized to address the problem of cholesterol localization in rat tissues. Rat kidneys were fixed, cryoprotected by sucrose, frozen, sectioned by cryoultramicrotomy, and dried at room temperature. The samples were either covered with a thin silver layer or analyzed uncovered in an imaging TOF-SIMS instrument equipped with an Au -source. The yield of desorbed secondary ions for some species was up to 600-fold higher after silver coating of the samples. Reference samples of cholesterol were silver-coated and analyzed by TOF-SIMS to define significant peaks, specific for cholesterol. Such peaks were found at m/z = 386 (C27H46O+), m/z = 493 (C27H46O107Ag+), m/z = 495 (C27H46O109Ag+), m/z = 879 (C54H92O2107Ag+), and m/z = 881 (C54H92O2109Ag+). The silver-cationized cholesterol (493 , m/z , 495) signal was localized by imaging TOF-SIMS in the kidney sections and showed a high cholesterol content in the kidney glomeruli. A more diffuse distribution of cholesterol was also found over areas representing the cytoplasm or plasma membrane of the epithelial cells in the proximal tubules of rat kidney. Microsc. Res. Tech. 65:282,286, 2004. © 2005 Wiley-Liss, Inc. [source] Purification, crystallization and preliminary X-ray analysis of FliT, a bacterial flagellar substrate-specific export chaperoneACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 8 2009Miki Kinoshita The assembly process of the bacterial flagellum is coupled to flagellar gene expression. FliT acts not only as a flagellar type III substrate-specific export chaperone for the filament-capping protein FliD but also as a negative regulator that suppresses flagellar gene expression through its specific interaction with the master regulator FlhD4C2 complex. In this study, FliT of Salmonella enterica serovar Typhimurium was expressed, purified and crystallized. Crystals of SeMet FliT were obtained by the sitting-drop vapour-diffusion technique with potassium/sodium tartrate as the precipitant. The crystals grew in the trigonal space group P3121 or P3221 and diffracted to 3.2,Å resolution. The anomalous difference Patterson map of the SeMet FliT crystal showed significant peaks in its Harker sections, indicating the usefulness of the derivative data for structure determination. [source] Crystallization and preliminary X-ray analysis of a C-terminal fragment of FlgJ, a putative flagellar rod cap protein from SalmonellaACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 1 2009Yuki Kikuchi The formation of the bacterial flagellar axial structure, including the filament, the hook and the rod, requires the attachment of a cap complex to the distal end of the growing structure. Because the rod penetrates the peptidoglycan (PG) layer, the rod cap complex is thought to have PG-hydrolyzing activity. FlgJ is a putative rod cap protein whose C-terminal region shows sequence similarity to known muramidases. In this study, FlgJ120,316, a C-terminal fragment of FlgJ which contains the muramidase region, was overproduced, purified and crystallized. Crystals were obtained by the sitting-drop vapour-diffusion technique using PEG 3350 as a crystallizing agent and belonged to the orthorhombic space group P212121, with unit-cell parameters a = 38.8, b = 43.9, c = 108.5,Å. Anomalous difference Patterson maps calculated from the diffraction data set of a selenomethionine-labelled crystal showed significant peaks in the Harker sections, indicating that the data were suitable for structure determination. [source] Crystallization and preliminary X-ray analysis of FliJ, a cytoplasmic component of the flagellar type III protein-export apparatus from Salmonella sp.ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 1 2009Tatsuya Ibuki The axial component proteins of the bacterial flagellum are synthesized in the cytoplasm and then translocated into the central channel of the flagellum by the flagellar type III protein-export apparatus for self-assembly at the distal growing end of the flagellum. FliJ is an essential cytoplasmic component of the export apparatus. In this study, Salmonella FliJ with an extra three residues (glycine, serine and histidine) attached to the N-terminus as the remainder of a His tag (GSH-FliJ) was purified and crystallized. Crystals were obtained by the sitting-drop vapour-diffusion technique using PEG 300 as a precipitant. GSH-FliJ crystals grew in the hexagonal space group P6122 or P6522. While the native crystals diffracted to 3.3,Å resolution, the diffraction resolution limit of mercury derivatives was extended to 2.1,Å. Anomalous and isomorphous difference Patterson maps of the mercury-derivative crystal showed significant peaks in their Harker sections, indicating the usefulness of the derivative data for structure determination. [source] Cloning, purification and preliminary X-ray analysis of the C-terminal domain of Helicobacter pylori MotBACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 4 2008Anna Roujeinikova The C-terminal domain of MotB (MotB-C) contains a putative peptidoglycan-binding motif and is believed to anchor the MotA/MotB stator unit of the bacterial flagellar motor to the cell wall. Crystals of Helicobacter pylori MotB-C (138 amino-acid residues) were obtained by the hanging-drop vapour-diffusion method using polyethylene glycol as a precipitant. These crystals belong to space group P21, with unit-cell parameters a = 50.8, b = 89.5, c = 66.3,Å, , = 112.5°. The crystals diffract X-rays to at least 1.6,Å resolution using a synchrotron-radiation source. Self-rotation function and Matthews coefficient calculations suggest that the asymmetric unit contains one tetramer with 222 point-group symmetry. The anomalous difference Patterson maps calculated for an ytterbium-derivative crystal using diffraction data at a wavelength of 1.38,Å showed significant peaks on the v = 1/2 Harker section, suggesting that ab initio phase information could be derived from the MAD data. [source] Confocal Raman Microscopy as a Tool to Investigate Concentration Profiles of Melt Crystallized Ibuprofen/Carnauba WaxCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 7 2009H. Qu Abstract Coatings are of great significance for pharmaceutical solid dosage forms. They fulfil a number of functions and are often necessary to control drug delivery, to mask bitter taste, or to protect the active pharmaceutical ingredient from detrimental environmental factors. The process of self-coating by melt crystallization of a suitable binary mixture eliminates the need for an additional process step in the manufacture of a solid drug. Self-coating relies upon the physical and spatial separation of individual components in a melt during solidification. This paper focuses on the use of confocal Raman microscopy as a nondestructive technique for quantifying the spatial distribution of the components in self-coated pastilles manufactured from the binary system ibuprofen/carnauba wax. Pastilles are produced from the melt. Raman spectroscopy allows the direct analysis of concentration profiles across the surface of the pastille. Here, the samples are cleaved and the cleaved surface is investigated in order to establish the distribution of the components in the interior of the solid. A univariate calibration model was developed and statistically validated with standard mixtures of ibuprofen and carnauba wax. Different regression models (linear or polynomial, using different significant peaks for the respective compounds) were assessed and a linear model was found to be adequate to determine the concentration gradient in the pastilles. [source] | ||||||||||||||||