bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pulsations and planets: The asteroseismology‐extrasolar‐planet connection
Authors: Schuh S. 
Published: May 2010

AbstractThe disciplines of asteroseismology and extrasolar planet science overlap methodically in the branch of high‐precision photometric time series observations. Light curves are, amongst others, useful to measure intrinsic stellar variability due to oscillations, as well as to discover and characterize those extrasolar planets that transit in front of their host stars, periodically causing shallow dips in the observed brightness. Both fields ultimately derive fundamental parameters of stellar and planetary objects, allowing to study for example the physics of various classes of pulsating stars, or the variety of planetary systems, in the overall context of stellar and planetary system formation and evolution. Both methods typically also require extensive spectroscopic follow‐up to fully explore the dynamic characteristics of the processes under investigation. In particularly interesting cases, a combination of observed pulsations and signatures of a planet allows to characterize a system's components to a very high degree of completeness by combining complementary information. The planning of the relevant space missions has consequently converged with respect to science cases, where at the outset there was primarily a coincidence in instrumentation and techniques. Whether space‐ or ground‐based, a specific type of stellar pulsations can themselves be used in an innovative way to search for extrasolar planets. Results from this additional method at the interface of stellar pulsation studies and exoplanet hunts in a beyond‐mainstream area are presented (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Open clusters and the galactic disk
Authors: Röser S. , Kharchenko N.V. , Piskunov A.E. , Schilbach E. , Scholz R.‐D. , Zinnecker H. 
Published: May 2010

AbstractIt is textbook knowledge that open clusters are conspicuous members of the thin disk of our Galaxy, but their role as contributors to the stellar population of the disk was regarded as minor. Starting from a homogenous stellar sky survey, the ASCC‐2.5, we revisited the population of open clusters in the solar neighbourhood from scratch. In the course of this enterprise we detected 130 formerly unknown open clusters, constructed volume‐ and magnitude‐limited samples of clusters, re‐determined distances, motions, sizes, ages, luminosities and masses of 650 open clusters. We derived the present‐day luminosity and mass functions of open clusters (not the stellar mass function in open clusters), the cluster initial mass function CIMF and the formation rate of open clusters. We find that open clusters contributed around 40 percent to the stellar content of the disk during the history of our Galaxy. Hence, open clusters are important building blocks of the Galactic disk (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
VLT‐CRIRES: “Good Vibrations” Rotational‐vibrational molecular spectroscopy in astronomy
Authors: Käufl H.U. 
Published: May 2010

AbstractNear‐Infrared high spectral and spatial resolution spectroscopy offers new and innovative observing opportunities for astronomy. The “traditional” benefits of IR‐astronomy – strongly reduced extinction and availability of adaptive optics – more than offset for many applications the compared to CCD‐based astronomy strongly reduced sensitivity. Especially in high resolution spectroscopy interferences by telluric lines can be minimized. Moreover for abundance studies many important atomic lines can be accessed in the NIR. A novel spectral feature available for quantitative spectroscopy are the molecular rotational‐vibrational transitions which allow for fundamentally new studies of condensed objects and atmospheres. This is also an important complement to radio‐astronomy, especially with ALMA, where molecules are generally only observed in the vibrational ground state. Rot‐vib transitions also allow high precision abundance measurements – including isotopic ratios – fundamental to understand the thermo‐nuclear processes in stars beyond the main sequence. Quantitative modeling of atmospheres has progressed such that the unambiguous interpretation of IR‐spectra is now well established. In combination with adaptive optics spectro‐astrometry is even more powerful and with VLT‐CRIRES a spatial resolution of better than one milli‐arcsecond has been demonstrated. Some highlights and recent results will be presented: our solar system, extrasolar planets, star‐ and planet formation, stellar evolution and the formation of galactic bulges (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Conformations of Betanova in aqueous trifluoroethanol
Authors: Chagolla Danny P. , Gerig John T. 
Published: May 2010

AbstractConformations of the designed peptide Betanova in 42% trifluoroethanol/water (v/v) were explored. Circular dichroism (CD) observations provided no evidence for the presence of significant amounts of β‐structures in water, in TFE/water, or in ethanol/water. Nuclear magnetic resonance (NMR) diffusion experiments showed no significant difference in the hydrodynamic radius of the peptide in water and in 42% TFE/water. However, calculations indicated that the hydrodynamic radii of the triple‐stranded β‐sheet, originally proposed for Betanova by Kortemme et al. (Science 1998, 281, 253‐256), and a variety of partially folded forms of Betanova would be similar and likely could not be convincingly distinguished by diffusion experiments. Temperature coefficients (Δδ/ΔT) of the peptide NH chemical shifts are similar in water and 42% TFE/water, implying that most of these protons are highly solvent exposed in both solvents and likely do not participate in intramolecular hydrogen bonding interactions. Possible exceptions to this conclusion are the Lys9 and Lys15 residues, where a more positive coefficient may indicate that these residues are involved to some extent in local turn structures. Peptide proton–solvent fluorine intermolecular nuclear Overhauser effect (NOE)s at 25°C were consistent with the presence of a mixture of conformations, which could include the triple‐stranded β‐sheet structure as a minor component. At 0°C, peptide‐TFE NOEs indicated that TFE interacts strongly enough with many protons of Betanova that alcohol‐peptide interactions persist for times of the order of nanoseconds, appreciably longer than the encounter time characteristic of mutual diffusion of TFE and the solute. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 893–903, 2010.
The role of disulfide bonds and N‐terminus in the structural properties of hepcidins: Insights from molecular dynamics simulations
Authors: Aschi Massimiliano , Bozzi Argante , Di Bartolomeo Renato , Petruzzelli Raffaele 
Published: May 2010

AbstractThe main purpose of this work is to analyse, by means of molecular dynamics (MD) simulations both structural and mechanical‐dynamical differences between Hepcidin‐20 and Hepcidin‐25 in both oxidized and reduced states in aqueous solution. Results indicate that the presence of disulfide bonds is essential, in both peptides, for maintaining their β‐hairpin motif. As a matter of fact, the lack of this intra‐peptide covalent interactions produces an almost immediate deviation from the oxidized, plausibly active, structure in both the systems. Interestingly, reduced Hepcidin‐25 turns out to be characterized by a highly fluctuating structure which is found to rapidly span a large number of configurations at equilibrium. On the other hand, loss of disulfide bonds in the shorter peptide, results in a more compact and relatively rigid double‐turn structure. Comparison of mechanical–dynamical properties and sidechains–sidechains interactions in oxidized Hepcidin‐20 and Hepcidin‐25 strongly suggest also the key role of N‐terminus in the aggregation tendency of Hepcidin‐25. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 917–926, 2010.
Using non‐invasive magnetic resonance imaging (MRI) to assess the reduction of Cr(VI) using a biofilm–palladium catalyst
Authors: Beauregard D.A. , Yong P. , Macaskie L.E. , Johns M.L. 
Published: May 2010

AbstractIndustrial waste streams may contain contaminants that are valuable like Pd(II) and/or toxic and mutagenic like Cr(VI). Using Serratia sp. biofilm the former was biomineralized to produce a supported nanocrystalline Pd(0) catalyst, and this biofilm–Pd heterogeneous catalyst was then used to reduce Cr(VI) to less dangerous Cr(III) at room temperature, with formate as the electron donor. Cr(VI)(aq) is non‐paramagnetic while Cr(III)(aq) is paramagnetic, which enabled spatial mapping of Cr species concentrations within the reactor cell using non‐invasive magnetic resonance (MR) imaging experiments. Spatial reactivity heterogeneities were thus examined. In batch reactions, these could be attributed primarily to heterogeneity of Pd(0) distribution and to the development of gas bubbles within the reactor. In continuous flow reactions, spatial reactivity heterogeneities resulted primarily from heterogeneity of Cr(VI) delivery. Biotechnol. Bioeng. 2010;107: 11–20. © 2010 Wiley Periodicals, Inc.
Optimal nitrogen supply as a key to increased and sustained production of a monoclonal full‐size antibody in BY‐2 suspension culture
Authors: Holland T. , Sack M. , Rademacher T. , Schmale K. , Altmann F. , Stadlmann J. , Fischer R. , Hellwig S. 
Published: May 2010

AbstractPlant cell cultures have been used as expression hosts for recombinant proteins for over two decades. The quality of plant cell culture‐produced proteins such as full‐size monoclonal antibodies has been shown to be excellent in terms of protein folding and binding activity, but the productivity and yield fell short of what was achieved using mammalian cell culture, in which the key to gram‐per‐liter expression levels was strain selection and medium/process optimization. We carried out an extensive media analysis and optimization for the production of the full‐size human anti‐HIV antibody 2G12 inN. tabacumcv. BY‐2. Nitrogen source and availability was found to be one key factor for the volumetric productivity of plant cell cultures. Increased amounts of nitrate in the culture medium had a dramatic impact on protein yields, resulting in a 10–20‐fold increase in product accumulation through a combination of enhanced secretion and higher stability. The results were scalable from shake flasks to stirred‐tank bioreactors, where the maximum yield per cultivation volume was 8 mg L−1over 7 days. During the stationary phase, antibody levels were 150‐fold higher in nitrogen‐enriched medium compared to standard medium. The enhanced medium appeared not to affect antibody quality and activity, as determined by Western blots, surface plasmon resonance binding assays andN‐glycan analysis. Biotechnol. Bioeng. 2010;107: 278–289. © 2010 Wiley Periodicals, Inc.
Inhibition of starch synthesis results in overproduction of lipids in Chlamydomonas reinhardtii
Authors: Li Yantao , Han Danxiang , Hu Guangrong , Sommerfeld Milton , Hu Qiang 
Published: May 2010

AbstractStarch and neutral lipids are two major carbon storage compounds in many microalgae and plants. Lipids are more energy rich and have often been used as food and fuel feedstocks. Genetic engineering of the lipid biosynthesis pathway to overproduce lipid has achieved only limited success. We hypothesize that through blocking the competing pathway to produce starch, overproduction of neutral lipid may be achieved. This hypothesis was tested using the green microalga Chlamydomonas reinhardtii and its low starch and starchless mutants. We discovered that a dramatic increase in neutral lipid content and the neutral lipid/total lipid ratio occurred among the mutants under high light and nitrogen starvation. BAFJ5, one of the mutants defective in the small subunit of ADP‐glucose pyrophosphorylase, accumulated neutral and total lipid of up to 32.6% and 46.4% of dry weight (DW) or 8‐ and 3.5‐fold higher, respectively, than the wild‐type. These results confirmed the feasibility of increasing lipid production through redirecting photosynthetically assimilated carbon away from starch synthesis to neutral lipid synthesis. However, some growth impairment was observed in the low starch and starchless mutants, possibly due to altered energy partitioning in PSII, with more excitation energy dissipated as heat and less to photochemical conversion. This study demonstrated that biomass and lipid production by the selected mutants can be improved by physiological manipulation. Biotechnol. Bioeng. 2010;107: 258–268. © 2010 Wiley Periodicals, Inc.
Effect of carbon source addition on toluene biodegradation by an Escherichia coli DH5α transconjugant harboring the TOL plasmid
Authors: Ikuma Kaoru , Gunsch Claudia 
Published: May 2010

AbstractHorizontal gene transfer (HGT) of plasmids is a naturally occurring phenomenon which could be manipulated for bioremediation applications. Specifically, HGT may prove useful to enhance bioremediation through genetic bioaugmentation. However, because the transfer of a plasmid between donor and recipient cells does not always result in useful functional phenotypes, the conditions under which HGT events result in enhanced degradative capabilities must first be elucidated. The objective of this study was to determine if the addition of alternate carbon substrates could improve toluene degradation in Escherichia coli DH5α transconjugants. The addition of glucose (0.5–5 g/L) and Luria–Bertani (LB) broth (10–100%) resulted in enhanced toluene degradation. On average, the toluene degradation rate increased 14.1 (±2.1)‐fold in the presence of glucose while the maximum increase was 18.4 (±1.7)‐fold in the presence of 25% LB broth. Gene expression of xyl genes was upregulated in the presence of glucose but not LB broth, which implies different inducing mechanisms by the two types of alternate carbon source. The increased toluene degradation by the addition of glucose or LB broth was persistent over the short‐term, suggesting the pulse amendment of an alternative carbon source may be helpful in bioremediation. While the effects of recipient genome GC content and other conditions must still be examined, our results suggest that changes in environmental conditions such as alternate substrate availability may significantly improve the functionality of the transferred phenotypes in HGT and therefore may be an important parameter for genetic bioaugmentation optimization. Biotechnol. Bioeng. 2010;107: 269–277. © 2010 Wiley Periodicals, Inc.
Growth, lipid content, productivity, and fatty acid composition of tropical microalgae for scale‐up production
Authors: Huerlimann Roger , de Nys Rocky , Heimann Kirsten 
Published: May 2010

AbstractBiomass and lipid productivity, lipid content, and quantitative and qualitative lipid composition are critical parameters in selecting microalgal species for commercial scale‐up production. This study compares lipid content and composition, and lipid and biomass productivity during logarithmic, late logarithmic, and stationary phase of Nannochloropsis sp., Isochrysis sp., Tetraselmis sp., and Rhodomonas sp. grown in L1‐, f/2‐, and K‐medium. Of the tested species, Tetraselmis sp. exhibited a lipid productivity of 3.9–4.8 g m−2 day−1 in any media type, with comparable lipid productivity by Nannochloropsis sp. and Isochrysis sp. when grown in L1‐medium. The dry biomass productivity of Tetraselmis sp. (33.1–45.0 g m−2 day−1) exceeded that of the other species by a factor 2–10. Of the organisms studied, Tetraselmis sp. had the best dry biomass and/or lipid production profile in large‐scale cultures. The present study provides a practical benchmark, which allows comparison of microalgal production systems with different footprints, as well as terrestrial systems. Biotechnol. Bioeng. 2010;107: 245–257. © 2010 Wiley Periodicals, Inc.
Disperse distribution of cationic amino acids on hydrophilic surface of helical wheel enhances antimicrobial peptide activity
Authors: Kim Young Soo , Cha Hyung Joon 
Published: May 2010

AbstractThe antimicrobial action of amphipathic antimicrobial peptides (AMPs) generally depends on perturbation of the bacterial membrane via electrostatic interactions promoting initial binding to the surface and hydrophobic interactions for pore formation into the membrane. Several studies have focused on the structure–activity relationship (SAR) of AMPs by modulation of structural parameters. However, modulation of one parameter commonly induces simultaneous changes in other parameters, making it difficult to investigate the specific influence of a single variable. In the present work, we investigated the distribution effect of cationic amino acids on the hydrophilic surface of the helical wheel using model AMPs composed of only lysine (K) and leucine (L) as representative cationic and hydrophobic residues, respectively, under conditions in which other parameters are fixed. Based on SAR analyses of α‐helical KL model AMPs displaying different cationic distributions, we propose that the dispersity of cationic amino acids on the hydrophilic surface is a factor that contributes to the antimicrobial activity of AMP. Moreover, antimicrobial activity is enhanced by rearrangement of cationic amino acids to promote dispersed distribution. We confirmed the cationic distribution effect using natural AMP‐derived α‐helical CRAMP18 and its analogs. Our data show that accumulation of lysine shifts in the CRAMP18 analog leads to higher dispersion, and subsequently to improved antimicrobial activity. Therefore, we propose that the cationic distribution effect can be applied for the rational redesign of amino acid sequences to improve the antimicrobial activities of natural α‐helical AMPs, in combination with regulation of other known structural parameters. Biotechnol. Bioeng. 2010;107: 216–223. © 2010 Wiley Periodicals, Inc.
Ethanol production from paper sludge by simultaneous saccharification and co‐fermentation using recombinant xylose‐fermenting microorganisms
Authors: Zhang Jiayi , Lynd Lee R. 
Published: May 2010

AbstractSimultaneous saccharification and co‐fermentation (SSCF) of waste paper sludge to ethanol was investigated using two recombinant xylose‐fermenting microbes: Zymomonas mobilis 8b and Saccharomyces cerevisiae RWB222. S. cerevisiae RWB222 produced over 40 g/L ethanol with a yield of 0.39 g ethanol/g carbohydrate on paper sludge at 37°C, while similar titers and yields were achieved by Z. mobilis 8b at 30°C. Both S. cerevisiae RWB222 and Z. mobilis 8b exhibited decreasing cell viability at 37°C when producing over 40 g/L ethanol. A high ethanol concentration can account for S. cerevisiae RWB222 viability loss, but ethanol concentration was not the only factor influencing Z. mobilis 8b viability loss at 37°C. Over 3 g/L residual glucose was observed at the end of paper sludge SSCF by Z. mobilis 8b, and a statistical analysis revealed that a high calcium concentration originating from paper sludge, a high ethanol concentration, and a high temperature were the key interactive factors resulting in glucose accumulation. The highest ethanol yields were achieved by SSCF of paper sludge with S. cerevisiae RWB222 at 37°C and Z. mobilis 8b at 30°C. With good sugar consumption at 37°C, S. cerevisiae RWB222 was able to gain an improvement in the polysaccharide to sugar yield compared to that at 30°C, whereas Z. mobilis 8b at 30°C had a lower polysaccharide to sugar yield, but a higher sugar to ethanol yield than S. cerevisiae. Both organisms under optimal conditions achieved a 19% higher overall conversion of paper sludge to ethanol than the non‐xylose utilizing S. cerevisiae D5A at its optimal process temperature of 37°C. Biotechnol. Bioeng. 2010;107: 235–244. © 2010 Wiley Periodicals, Inc.
An investigation of intracellular glycosylation activities in CHO cells: Effects of nucleotide sugar precursor feeding
Authors: Wong Niki S.C. , Wati Lydia , Nissom Peter M. , Feng H.T. , Lee M.M. , Yap Miranda G.S. 
Published: May 2010

AbstractControlling glycosylation of recombinant proteins produced by CHO cells is highly desired as it can be directed towards maintaining or increasing product quality. To further our understanding of the different factors influencing glycosylation, a glycosylation sub‐array of 79 genes and a capillary electrophoresis method which simultaneously analyzes 12 nucleotides and 7 nucleotide sugars; were used to generate intracellular N‐glycosylation profiles. Specifically, the effects of nucleotide sugar precursor feeding on intracellular glycosylation activities were analyzed in CHO cells producing recombinant human interferon‐γ (IFN‐γ). Galactose (±uridine), glucosamine (±uridine), and N‐acetylmannosamine (ManNAc) (±cytidine) feeding resulted in 12%, 28%, and 32% increase in IFN‐γ sialylation as compared to the untreated control cultures. This could be directly attributed to increases in nucleotide sugar substrates, UDP‐Hex (∼20‐fold), UDP‐HexNAc (6‐ to 15‐fold) and CMP‐sialic acid (30‐ to 120‐fold), respectively. Up‐regulation of B4gal and St3gal could also have enhanced glycan addition onto the proteins, leading to more complete glycosylation (sialylation). Combined feeding of glucosamine + uridine and ManNAc + cytidine increased UDP‐HexNAc and CMP‐sialic acid by another two‐ to fourfold as compared to feeding sugar precursors alone. However, it did not lead to a synergistic increase in IFN‐γ sialylation. Other factors such as glycosyltransferase or glycan substrate levels could have become limiting. In addition, uridine feeding increased the levels of uridine‐ and cytidine‐activated nucleotide sugars simultaneously, which could imply that uridine is one of the limiting substrates for nucleotide sugar synthesis in the study. Hence, the characterization of intracellular glycosylation activities has increased our understanding of how nucleotide sugar precursor feeding influence glycosylation of recombinant proteins produced in CHO cells. It has also led to the optimization of more effective strategies for manipulating glycan quality. Biotechnol. Bioeng. 2010;107: 321–336. © 2010 Wiley Periodicals, Inc.
Rapid characterization and quality control of complex cell culture media solutions using raman spectroscopy and chemometrics
Authors: Li Boyan , Ryan Paul W. , Ray Bryan H. , Leister Kirk J. , Sirimuthu Narayana M.S. , Ryder Alan G. 
Published: May 2010

AbstractThe use of Raman spectroscopy coupled with chemometrics for the rapid identification, characterization, and quality assessment of complex cell culture media components used for industrial mammalian cell culture was investigated. Raman spectroscopy offers significant advantages for the analysis of complex, aqueous‐based materials used in biotechnology because there is no need for sample preparation and water is a weak Raman scatterer. We demonstrate the efficacy of the method for the routine analysis of dilute aqueous solution of five different chemically defined (CD) commercial media components used in a Chinese Hamster Ovary (CHO) cell manufacturing process for recombinant proteins.The chemometric processing of the Raman spectral data is the key factor in developing robust methods. Here, we discuss the optimum methods for eliminating baseline drift, background fluctuations, and other instrumentation artifacts to generate reproducible spectral data. Principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA) were then employed in the development of a robust routine for both identification and quality evaluation of the five different media components. These methods have the potential to be extremely useful in an industrial context for “in‐house” sample handling, tracking, and quality control. Biotechnol. Bioeng. 2010;107: 290–301. © 2010 Wiley Periodicals, Inc.