bluuebunny/crossref_metadata_2025 huggingface dataset:
Bell Labs experiments with auto-exhaust catalysts
Authors: Lubkin Gloria B.
Published: December 2008

In an attempt to understand the mechanism of catalysis a Bell Labs group has found a class of compounds that are good catalysts for the oxidation of carbon monoxide. The Bell group, Rudie Voorhoeve, Joseph Remeika, Paul Freeland and Bernd Matthias (also at the University of California, La Jolla), says that the compounds are Promising substitutes for platinum in devices for catalytically treating automobile exhaust.
Eugene Wigner—a tribute on his seventieth birthday
Authors: Seitz Frederick
Published: December 2008

It was in 1930 that Eugene Wigner joined the staff of Princeton on a halftime basis, at the age of 27, sharing a professorship with John von Neumann. Both were members of that remarkably illustrious group of students who had emerged almost as a team in Budapest and then accepted employment in Germany in the last great days of German science. Leo Szilard once confided to me that the group was really not composed of Hungarians but of Martians in disguise.
Helium-three transitions suggest a superfluid state
Authors: Rothenberg Marian S.
Published: December 2008

Is liquid helium-three a superfluid? This is a possible explanation of some nuclear magnetic resonance studies done at Cornell. The results, which appear to show two transitions in the liquid at temperatures in the region of a few millidegrees Kelvin, could be experimental evidence for a phenomenon first predicted in the early 1960's.
Farewell to Utah's W-particle
Authors: Lubkin Gloria B.
Published: December 2008

Last year a group at the University of Utah said that the anomalous muon flux they had been observing in cosmic rays since 1966 was consistent with the observation of a W particle or intermediate vector boson (PHYSICS TODAY, November 1971, page 17). At the XVI Conference on High-Energy Physics (held at both the University of Chicago and the National Accelerator Laboratory) in September the group, Haven E. Bergeson, Gary Carlson, Jack Keuffel and James Morrison announced what Keuffel called “the obituary of the Utah effect.” Keuffel told us, “Alas, no W's. It was fun while it lasted!”
Elastic surface waves
Authors: de Klerk John
Published: December 2008

Devices that exploit the properties of elastic surface waves can perform very complex signal-processing functions, identical to those carried out by conventional electromagnetic devices. The great advantage to using surface waves instead of electromagnetic waves is the tremendous reduction in size of surface-wave devices compared to their electromagnetic counterparts. This great reduction in size is the result of the great difference between the elastic and electromagnetic velocities. Surface waves propagate at velocities approximately 105 times slower than electromagnetic velocities; thus, at the same frequency, the elastic wavelength is 105 times shorter than the electromagnetic wavelength. A further advantage is that the energy in the elastic surface wave can readily be sensed anywhere along its path.
The cosmic numbers
Authors: Harrison Edward R.
Published: December 2008

Cosmic numbers have intrigued modern cosmologists ever since puzzling coincidences were first noticed between some of the large dimensionless constants. Here I will try to show not only that these numbers are interesting, but also that they are possibly important to our understanding of the physical world. Have the coincidences always existed or is it merely fortuitous that they occur at the present stage of evolution of the universe?
Integrated management of vulpia in dryland perennial pastures of southern Australia
Authors: Tozer K. N. , Chapman D. F. , Quigley P. E. , Dowling P. M. , Cousens R. D. , Kearney G. A.
Published: January 2009

Vulpia (Vulpia species C.C. Gmel.) are annual grass weeds that can reduce pasture quality and stock-carrying capacity of perennial pastures throughout southern Australia. To develop more effective strategies to control vulpia, an experiment was established in western Victoria (average annual rainfall 565 mm) in phalaris (Phalaris aquatica L.) pastures comparing the effects of control methods [comprising combinations of fertiliser addition (Fert), a single herbicide (simazine) application (Sim), and pasture rest from grazing (Rest)] on vulpia populations. A further herbicide treatment [paraquat-diquat (SpraySeed®)] was imposed on some of these treatments. Measurements included botanical composition, phalaris and vulpia tiller density, seed production, and number of residual seeds in the soil. Vulpia content remained unchanged in the Sim-Rest treatment but increased in all other management treatments over the duration of the 3 year study and especially where paraquat-diquat was applied, despite paraquat-diquat causing an initial reduction in vulpia content. Vulpia content was lowest in the Fert-Sim-Rest treatment. The Fert-Sim treatment and in some cases paraquat-diquat application reduced vulpia tiller production. Vulpia seed production and the residual seed population were not influenced by any of the management treatments, while the single paraquat-diquat application increased vulpia seed production 18 months after application. Phalaris content was enhanced by the Sim-Rest and Fert-Sim-Rest treatments and initially by paraquat-diquat. No treatment affected phalaris tiller production and basal cover. The subterranean clover (Trifolium subterraneum L.) content declined during the experiment, but to a lesser extent where paraquat-diquat was applied. Volunteer species content was initially suppressed in the year following paraquat-application, although populations recovered after this time. Of the two Vulpia spp. present (V. bromoides (L.) S.F. Gray and V. myuros (L.) C.C. Gmelin), V. bromoides was the most prevalent. Results show how a double herbicide application can increase vulpia fecundity and rate of re-infestation of herbicide-treated sites. Pasture rest shows some promise, but to a lesser extent than in the New South Wales tablelands, where summer rainfall may increase the growth of perennial species. In lower rainfall, summer dry areas, responses to pasture rest may be slower. Despite this, integrated management (which combines strategies such as pasture rest, herbicide application, and fertiliser application) increases the perennial content and reduces vulpia seed production, thus improving vulpia control.
Contrasted patterns of hyperdiversification in Mediterranean hotspots
Authors: Sauquet Hervé , Weston Peter H. , Anderson Cajsa Lisa , Barker Nigel P. , Cantrill David J. , Mast Austin R. , Savolainen Vincent
Published: December 2008

Dating the Tree of Life has now become central to relating patterns of biodiversity to key processes in Earth history such as plate tectonics and climate change. Regions with a Mediterranean climate have long been noted for their exceptional species richness and high endemism. How and when these biota assembled can only be answered with a good understanding of the sequence of divergence times for each of their components. A critical aspect of dating by using molecular sequence divergence is the incorporation of multiple suitable age constraints. Here, we show that only rigorous phylogenetic analysis of fossil taxa can lead to solid calibration and, in turn, stable age estimates, regardless of which of 3 relaxed clock-dating methods is used. We find that Proteaceae, a model plant group for the Mediterranean hotspots of the Southern Hemisphere with a very rich pollen fossil record, diversified under higher rates in the Cape Floristic Region and Southwest Australia than in any other area of their total distribution. Our results highlight key differences between Mediterranean hotspots and indicate that Southwest Australian biota are the most phylogenetically diverse but include numerous lineages with low diversification rates.
Biallelic, ubiquitous transcription from the distal germline Igκ locus promoter during B cell development
Authors: Amin Rupesh H. , Cado Dragana , Nolla Hector , Huang Dan , Shinton Susan A. , Zhou Yan , Hardy Richard R. , Schlissel Mark S.
Published: December 2008

Allelic exclusion of
Ig
gene expression is necessary to limit the number of functional receptors to one per B cell. The mechanism underlying allelic exclusion is unknown. Because germline transcription of
Ig
and
TCR
loci is tightly correlated with rearrangement, we created two novel knock-in mice that report transcriptional activity of the Jκ germline promoters in the
Ig
κ locus. Analysis of these mice revealed that germline transcription is biallelic and occurs in all pre-B cells. Moreover, we found that the two germline promoters in this region are not equivalent but that the distal promoter accounts for the vast majority of observed germline transcript in pre-B cells while the activity of the proximal promoter increases later in development. Allelic exclusion of the
Ig
κ locus thus occurs at the level of rearrangement, but not germline transcription.
Scaffold-based discovery of indeglitazar, a PPAR pan-active anti-diabetic agent
Authors: Artis Dean R. , Lin Jack J. , Zhang Chao , Wang Weiru , Mehra Upasana , Perreault Mylene , Erbe David , Krupka Heike I. , England Bruce P. , Arnold James , Plotnikov Alexander N. , Marimuthu Adhirai , Nguyen Hoa , Will Sarah , Signaevsky Maxime , Kral John , Cantwell John , Settachatgull Calvin , Yan Douglas S. , Fong Daniel , Oh Angela , Shi Shenghua , Womack Patrick , Powell Benjamin , Habets Gaston , West Brian L. , Zhang Kam Y. J. , Milburn Michael V. , Vlasuk George P. , Hirth K. Peter , Nolop Keith , Bollag Gideon , Ibrahim Prabha N. , Tobin James F.
Published: December 2008

In a search for more effective anti-diabetic treatment, we used a process coupling low-affinity biochemical screening with high-throughput co-crystallography in the design of a series of compounds that selectively modulate the activities of all three peroxisome proliferator-activated receptors (PPARs), PPARα, PPARγ, and PPARδ. Transcriptional transactivation assays were used to select compounds from this chemical series with a bias toward partial agonism toward PPARγ, to circumvent the clinically observed side effects of full PPARγ agonists. Co-crystallographic characterization of the lead molecule, indeglitazar, in complex with each of the 3 PPARs revealed the structural basis for its PPAR pan-activity and its partial agonistic response toward PPARγ. Compared with full PPARγ-agonists, indeglitazar is less potent in promoting adipocyte differentiation and only partially effective in stimulating adiponectin gene expression. Evaluation of the compound in vivo confirmed the reduced adiponectin response in animal models of obesity and diabetes while revealing strong beneficial effects on glucose, triglycerides, cholesterol, body weight, and other metabolic parameters. Indeglitazar has now progressed to Phase II clinical evaluations for Type 2 diabetes mellitus (T2DM).
Wnt signaling targets ETO coactivation domain of TAF4/TFIID in vivo
Authors: Wright Kevin J. , Tjian Robert
Published: December 2008

Understanding the diverse activities of the multisubunit core promoter recognition complex TFIID in vivo requires knowledge of how individual subunits contribute to overall functions of this TATA box-binding protein (TBP)/TBP-associated factor (TAF) complex. By generating altered holo-TFIID complexes in
Drosophila
we identify the ETO domain of TAF4 as a coactivator domain likely targeted by Pygopus, a protein that is required for Wingless-induced transcription of
naked cuticle
. These results establish a coactivator function of TAF4 and provide a strategy to dissect mechanisms of TFIID function in vivo.
Can Assessment Reactivity Predict Treatment Outcome among Adolescents with Alcohol and Other Substance Use Disorders?
Authors: Kaminer Yifrah , Burleson Joseph A. , Burke Rebecca H.
Published: December 2008

The objectives of this paper are two-fold: to examine first, if the change from positive to negative alcohol and any other substance use status from baseline assessment to the onset of the first session (i.e., pre-treatment phase) occurs in adolescents, that is, Assessment Reactivity (AR); second, whether AR predicts treatment outcome. Participants were 177 adolescents with alcohol and other substance use disorders (AOSUD) in a 9-weekly group sessions of cognitive behavioral therapy. Drug urinalysis results at baseline assessment, first and last session and self-report for alcohol use were used as outcome measures. Participants showed a highly significant shift to non-use of both alcohol and of other substances from intake assessment to first session and from first to last session. Alcohol and substance use at first session predicted use at last session. This is the first study in youth asserting Assessment Reactivity as a valid construct during the pretreat-ment phase. AR should be considered in any analysis targeting treatment outcomes.
An Emerging Problem: Methamphetamine Abuse among Treatment Seeking Youth
Authors: Gonzales Rachel , Ang Alfonso , McCann Michael J. , Rawson Richard A.
Published: December 2008

This study examined correlates of methamphetamine (MA) and marijuana (MJ) use and treatment response among treatment-involved youth (N = 4,430) in Los Angeles County, California treated between 2000 and 2005. Of the sample, 912 (21%) were primary MA and 3,518 (79%) were primary MJ users. Correlates of increased MA use included being female, White, Asian or Latino, older age, previous treatment involvement, legal status of probation or parole, and initiating drug use at an older age. Treatment trends showed a rise in treatment admissions for MA, with more MA users enrolling in residential treatment compared to outpatient treatment. Predictors of retention, drug use at discharge, and completion by treatment modality are discussed. Results can guide the development of effective strategies for treatment assessment and planning tailored towards minimizing drug use and maximizing treatment response among youth.
Marijuana Neurobiology and Treatment
Authors: Elkashef Ahmed , Vocci Frank , Huestis Marilyn , Haney Margaret , Budney Alan , Gruber Amanda , el-Guebaly Nady
Published: December 2008

Marijuana is the number one illicit drug of abuse worldwide and a major public health problem, especially in the younger population. The objective of this article is to update and review the state of the science and treatments available for marijuana dependence based on a pre-meeting workshop that was presented at ISAM 2006. At the workshop, several papers were presented addressing the neurobiology and pharmacology of marijuana and treatment approaches, both psychotherapy and medications, for marijuana withdrawal. Medicolegal and ethical issues concerning marijuana medical use were also discussed. Concise summaries of these presentations are incorporated in this article, which is meant to be an updated review of the state of the science. Major advances have been made in understanding the underpinning of marijuana dependence and the role of the CNS cannabinoid system, which is a major area for targeting medications to treat marijuana withdrawal and dependence, as well as other addictions.

Behavioral therapies are efficacious for facilitating abstinence from marijuana. Nefazadone, Marinol, and buspirone are showing early positive signals for efficacy in ameliorating marijuana withdrawal symptoms. Effective psychotherapeutic approaches are available and promising medications studies need to be confirmed in outpatient trials. The next few years looking promising for translational research efforts to make treatment widely accessible to patients with marijuana dependence.
The Teen Addiction Severity Index around the Globe: The Tower of Babel Revisited
Authors: Kaminer Yifrah
Published: December 2008

The objectives of this article are, first, to provide a brief review of screening and assessment of adolescents substance use and substance use disorders; second, to describe the work done with the Teen Addiction Severity Index (T-ASI) in different countries; and third, to address challenges and opportunities in order to improve international collaboration between health professionals responsible for providing substance abuse services for youth and families. It is recommended that the International Society of Addiction Medicine (ISAM) sponsor and coordinate the efforts to disseminate the benefits accrued from already developed assessment and treatment of substance use disorders of youth into different countries and regions. Addiction professionals representing a myriad of cultures, ethnic, and racial groups would be encouraged to translate the assessments into relevant languages and dialects and with the support of the original authors conduct reverse translation and then test the psychometric properties before a wider use commences.
Review: Alcohol Use and Problems among Immigrants from the Former Soviet Union in Israel
Authors: Weiss Shoshana
Published: December 2008

This paper attempts to deal with multiple issues, provide data, and cover the current state of alcohol use among immigrants from the Former Soviet Union (FSU) in Israel. A comprehensive review of all studies published in the professional literature (mainly in Hebrew), as well as in reports and theses in Hebrew, is presented. This is an attempt to correct the lack of information among English readers about alcohol use patterns and problems in the Russian immigrant community in Israel. This paper is the first summary of findings in the alcohol use domain—epidemiology, treatment, and homelessness in relation to FSU immigrants in Israel. The review identifies alcohol use among recent FSU immigrants as more prevalent than among the Jewish-Israeli–absorbing society, and shows that FSU immigrants are overrepresented in treatment, and that most of the homeless persons in Israel are FSU immigrants and alcoholics. The paper also describes findings from other FSU immigrant studies in related fields such as genetics, workplace issues, pregnancy, emergency rooms and driving. Recommendations for future activities include the need for special analysis and focus on the FSU immigrants in national studies, as well as further investigations about cultural effects on FSU immigrants’ drinking habits.
The Patients in Recovery (PIR) Perspective: Teaching Physicians about Methamphetamine
Authors: Walley Alexander Y. , Phillips Karran A. , Gordon Adam J.
Published: December 2008

Methamphetamine dependence is an emerging epidemic confronting physicians. In an effort to improve understanding of its impact, the authors presented an educational workshop at a national meeting for general internists featuring small group discussions with patients in recovery (PIR) from methamphetamine dependence. Participants rated the workshop highly, stating it would lead to concrete change in their teaching, research, or patient care practices and they would invite the workshop to their institution for presentation. Direct interaction with PIR was the most valued aspect of the workshop. Lessons learned included patient's fear of being “turned in” limits disclosure of methamphetamine use to physicians; active users have little insight into methamphetamine-related changes in physical appearance; and a sense of productivity reinforces ongoing methamphetamine use. Workshops that include small group discussions between physicians and PIR are an innovative, practical, and acceptable method to teach physicians about their role in helping patients with substance dependence.
Heat transport modelling in EXTRAP T2R
Authors: Frassinetti L. , Brunsell P.R. , Cecconello M. , Drake J.R.
Published: December 2008

A model to estimate the heat transport in the EXTRAP T2R reversed field pinch (RFP) is described. The model, based on experimental and theoretical results, divides the RFP electron heat diffusivity χe into three regions, one in the plasma core, where χe is assumed to be determined by the tearing modes, one located around the reversal radius, where χe is assumed not dependent on the magnetic fluctuations and one in the extreme edge, where high χe is assumed. The absolute values of the core and of the reversal χe are determined by simulating the electron temperature and the soft x-ray and by comparing the simulated signals with the experimental ones. The model is used to estimate the heat diffusivity and the energy confinement time during the flat top of standard plasmas, of deep F plasmas and of plasmas obtained with the intelligent shell.
Vibrational Spectra and Adsorption of Trisiloxane Superspreading Surfactant at Air/Water Interface Studied with Sum Frequency Generation Vibrational Spectroscopy
Authors: Feng Jun , Wu Dan , Wen Jia , Liu Shi-lin , Wang Hong-fei
Published: December 2008

The CH stretch vibrational spectra of the trisiloxane superspreading surfactant Silwet L-77 ((CH3)3SiOSi(CH3)(C3H6)(OCH2CH2)78OCH3)OSi(CH3)3) at the air/water interface are measured with the surface Sum Frequency Generation Vibrational Spectroscopy (SFG-VS). The spectra are dominated with the features from the SiCH3 groups around 2905 cm1 (symmetric stretch or SS mode) and 2957 cm1 (mostly the asymmetric stretch or AS mode), and with the weak but apparent contribution from the OCH2 groups around 2880 cm1 (symmetric stretch or SS mode). Comparison of the polarization dependent SFG spectra below and above the critical aggregate or micelle concentration (CAC) indicates that the molecular orientation of the CH related molecular groups remained unchanged at different surface densities of the Silwet L-77 surfactant. The SFG-VS adsorption isotherm suggested that there was no sign of Silwet L-77 bilayer structure formation at the air/water interface. The Gibbs adsorption free energy of the Silwet surfactant to the air/water interface is 42.20.8kcal/mol, indicating the unusually strong adsorption ability of the Silwet L-77 superspreading surfactant.
Expressions for Entropy Production Rate of Fuel Cells
Authors: Lin Tong-ling , Zhao Ying-ru , Chen Jin-can
Published: December 2008

On the basis of a general model of fuel cells, the entropy production rates of a fuel cell system under different conditions are derived by using theories of electrochemistry and thermodynamics. In order to analyze the influence of the irreversible losses existing in an actual fuel cell, the equivalent circuit of the fuel cell is introduced, so that the irreversible factor of the fuel cell may be determined directly as a function of the internal, leak and load resistances. Moreover, the maximum power output and efficiency of the fuel cell are calculated, the optimal operation of the fuel cell is discussed, and the matching condition of the load resistance is determined.
Resonance-Enhanced Photon Excitation Spectroscopy of the Even-Parity Autoionizing Rydberg States of Xe
Authors: Li Chun-yan , Wang Ting-ting , Zhen Jun-feng , Zhang Qun , Chen Yang
Published: December 2008

Xenon atoms were produced in their metastable states 5p56s[3/2]2 and 5p56s[1/2]o in a pulsed DC discharge in a beam, and subsequently excited to the even-parity autoionizing Rydberg states 5p5lp[3/2]1,[1/2]1, and 5p5nf [5/2] 3 using single photon excitation. The excitation spectra of the even-parity autoionizing resonance series from the metastable 129Xe were obtained by recording the autoionized Xe+ with time-of-flight ion detection in the photon energy range of 28000-42000 cm1. A wealth of autoionizing resonances were newly observed, from which more precise and systematic spectroscopic data of the level energies and quantum defects were derived.
Effect of Water Vapor Absorption on Measurements of Atmospheric Nitrate Radical by LP-DOAS
Authors: Li Su-wen , Liu Wen-qing , Xie Pin-hua , Yang Yi-jun , Chen De-bao , Li Zheng
Published: December 2008

During the measurement of atmospheric nitrate radical by long-path differential optical absorption spec-troscopy, water vapor strong absorption could affect the measurement of nitrate radical and detection limits of system. Under the tropospheric condition, the optical density of water vapor absorption is non-linearly dependent on column density. An effective method was developed to eliminate the effect of water vapor absorption. Reference spectra of water vapor based on the daytime atmospheric absorption spectra, when fitted together with change of cross section with water vapor column densities, gave a more accurate fitting of water vapor absorptions, thus its effect on the measurements of nitrate radical could be restricted to a minimum and detection limits of system reached 3.6 ppt. The modified method was applied during an intensive field campaign in the Pearl River Delta, China. The NO3 concentration in polluted air masses varied from 3.6 ppt to 82.5 ppt with an average level of 23.61.8 ppt.
Dissipative Particle Dynamics Simulations of Domain Growth and Phase Separation in Binary Immiscible Fluids
Authors: Zhao Ying , Liu Hong , Lu Zhong-yuan , Sun Chia-chung
Published: December 2008

It was investigated that the domain growth processes of spinodal decomposition with different quenching depth in two and three dimensional binary immiscible fluids by using parallel dissipative particle dynamics simulations. In two dimensions, the dynamic scaling exponent 1/2 for coalescence and 2/3 for inertial regimes in the shallow quench and strong finite size effects in the cases of deep quenching were obtained. In three dimensions, it was used that the diffusive regime with exponent n = 1/3 in the shallow quench and the inertial hydrodynamic regime with n = 2/3 for different quenches. The viscous effects are not clearly reflected, showing n = 1/2 in both shallow and deep quenches in this time period, due to the soft nature of interaction potential adopted in dissipative particle dynamics.
Preparation and Unimolecular-Micellization Behavior of Homopolymer of Surface-Active Monomer AMC14AB
Authors: Liu Kang-kai , Li Lei
Published: December 2008

(2-acrylamido) ethyl tetradecyl dimethylammonium bromide (AMC14AB) was polymerized in aqueous solution to form the homopolymer P(AMC14AB). The physicochemical properties of P(AMC14AB) in aqueous solution were mainly studied with fluorescent probe method, surface tension measurement and conductom-etry. The experimental results show that the aggregation morphology of P(AMC14AB) in aqueous solution is unimolecular micelle as expected. Being different from conventional multimolecular micelle systems, the unimolecular micelle system of P(AMC14AB) not only shows critical micellar concentration (CMC = 0), (i.e. once added to pure water, the surface tension decreases immediately in spite how small the density is), but also the surface tension stays almost the same with the concentration increasing. That is to say, there is no mutational point on the relationship curve between surface tension and concentration. Furthermore, the unimolecular micelle system of P(AMC14AB) has no Krafft temperature, i.e. at any temperature, so long as it is dissolved in water, the unimolecular micelles will form. Besides this, for the solubilization of hydrophobic organic substances, the unimolecular micelle system of P(AMC14AB) is obviously different from the common multimolecular micelle system, having no turning point on the relationship curve between toluene solubi-lizaion amount and P(AMC14AB) concentration, and the solubilizing ability of the unimolecular-micelle system of P(AMC14AB) for hydrophobic organic substances is much higher than that of the conventional multimolecular micelle solutions of common surfactants, such as centyl trimethyl ammonium bromide.
Photocatalysts of Cr Doped TiO2 Film Prepared by Micro Arc Oxidation
Authors: Wan Li , Li Jian-feng , Feng Jia-you , Sun Wei , Mao Zong-qiang
Published: December 2008

A series of Cr doped TiO2 films were prepared by micro arc oxidation (MAO) using an electrolyte of Na3PO4+K2Cr2O7. X-ray diffraction and scanning electron microscopy revealed that the films mainly consisted of anatase phase with a porous surface morphology. The films have an excellent photocatalytic effect for degradation of methylene blue and decomposition of water under visible light illumination. This arises from the formation of Cr3+/Cr4+ and oxygen vacancy energy levels owing to Cr doping. The former reduces the electron-hole recombination chance, while the latter generates a new gap between the conduction band (CB) and valence band (VB) of TiO2, which lowers the photo energy of the excited electron in the VB to the oxygen vacancy states. The mechanisms for film synthesis during the MAO process are also presented.
Photo-induced Alignment Behavior of Azobenzene-containing Polymer Films with Different Cross-linking Degree
Authors: Shen Jing , Huang Jin-tang , Luo Yan-hua , Zhang Qi-jin , Wang Ke-yi
Published: December 2008

Three series of amorphous copolymers containing azobenzene groups with various substituents and certain amounts of crosslinkable acrylic groups were prepared. The cross-linked polymer films were obtained by thermal polymerization of the acrylic groups in the copolymers, during which, by controlling the time of cross-linking reaction, the films can be made with different cross-linking degree (from 0 to 32%, which was monitored by FT-IR spectra measurement). Photo-induced alignment process of the films was performed under irradiation with linearly polarized light at 442 nm, and the effect of cross-linking degree on the photo-induced alignment rate was investigated. The dynamics of the photo-induced alignment was analyzed with biexponential curve fitting. The photo-induced alignment rate and the maximum transmittance of the films decreased because of the cross-linking. Furthermore, for the cross-linked samples, it was found that their saturated value of transmittances keep constant after repeated writing and erasing cycles. The findings reveal that the cross-linking of the film can effectively restrain the phototactic mass transport of azopolymer during irradiation by polarized light. The relationship between the cross-linking degree and the photo-induced alignment behavior of azopolymer is discussed in detail.
PTC1Is Required for Vacuole Inheritance and Promotes the Association of the Myosin-V Vacuole-specific Receptor Complex
Authors: Jin Yui , Taylor Eves P. , Tang Fusheng , Weisman Lois S.
Published: December 2008

Organelle inheritance occurs during cell division. In Saccharomyces cerevisiae, inheritance of the vacuole, and the distribution of mitochondria and cortical endoplasmic reticulum are regulated by Ptc1p, a type 2C protein phosphatase. Here we show that PTC1/VAC10 controls the distribution of additional cargoes moved by a myosin-V motor. These include peroxisomes, secretory vesicles, cargoes of Myo2p, and ASH1 mRNA, a cargo of Myo4p. We find that Ptc1p is required for the proper distribution of both Myo2p and Myo4p. Surprisingly, PTC1 is also required to maintain the steady-state levels of organelle-specific receptors, including Vac17p, Inp2p, and Mmr1p, which attach Myo2p to the vacuole, peroxisomes, and mitochondria, respectively. Furthermore, Vac17p fused to the cargo-binding domain of Myo2p suppressed the vacuole inheritance defect in ptc1Δ cells. These findings suggest that PTC1 promotes the association of myosin-V with its organelle-specific adaptor proteins. Moreover, these observations suggest that despite the existence of organelle-specific receptors, there is a higher order regulation that coordinates the movement of diverse cellular components.
Kinesin-14 Family Proteins HSET/XCTK2 Control Spindle Length by Cross-Linking and Sliding Microtubules
Authors: Cai Shang , Weaver Lesley N. , Ems-McClung Stephanie C. , Walczak Claire E.
Published: December 2008

Kinesin-14 family proteins are minus-end directed motors that cross-link microtubules and play key roles during spindle assembly. We showed previously that the Xenopus Kinesin-14 XCTK2 is regulated by Ran via the association of a bipartite NLS in the tail of XCTK2 with importin α/β, which regulates its ability to cross-link microtubules during spindle formation. Here we show that mutation of the nuclear localization signal (NLS) of human Kinesin-14 HSET caused an accumulation of HSET in the cytoplasm, which resulted in strong microtubule bundling. HSET overexpression in HeLa cells resulted in longer spindles, similar to what was seen with NLS mutants of XCTK2 in extracts, suggesting that Kinesin-14 proteins play similar roles in extracts and in somatic cells. Conversely, HSET knockdown by RNAi resulted in shorter spindles but did not affect pole formation. The change in spindle length was not dependent on K-fibers, as elimination of the K-fiber by Nuf2 RNAi resulted in an increase in spindle length that was partially rescued by co-RNAi of HSET. However, these changes in spindle length did require microtubule sliding, as overexpression of an HSET mutant that had its sliding activity uncoupled from its ATPase activity resulted in cells with spindle lengths shorter than cells overexpressing wild-type HSET. Our results are consistent with a model in which Ran regulates the association of Kinesin-14s with importin α/β to prevent aberrant cross-linking and bundling of microtubules by sequestering Kinesin-14s in the nucleus during interphase. Kinesin-14s act during mitosis to cross-link and slide between parallel microtubules to regulate spindle length.
Oxidative stress and disruption of labile iron generate specific auxotrophic requirements in Salmonella enterica
Authors: Thorgersen Michael P. , Downs Diana M.
Published: December 2008

The response of a cell to integrated stresses was investigated using environmental and/or genetic perturbations that disrupted labile iron homeostasis and increased oxidative stress. The effects of the perturbations were monitored as nutritional requirements, and were traced to specific enzymic targets. AyggX gshA cyaYmutant strain required exogenous thiamine and methionine for growth. The thiamine requirement, which had previously been linked to the Fe–S cluster proteins ThiH and ThiC, was responsive to oxidative stress and was not directly affected by manipulation of the iron pool. The methionine requirement was associated with the activity of sulfite reductase, an enzyme that appeared responsive to disruption of labile iron homeostasis. The results are incorporated in a model to suggest how the activity of iron-containing enzymes not directly sensitive to oxygen can be decreased by oxidation of the labile iron pool.
SufA – a bacterial enzyme that cleaves fibrinogen and blocks fibrin network formation
Authors: Karlsson Christofer , Mörgelin Matthias , Collin Mattias , Lood Rolf , Andersson Marie-Louise , Schmidtchen Artur , Björck Lars , Frick Inga-Maria
Published: December 2008

Finegoldia magnais a member of the normal human bacterial flora on the skin and other non-sterile body surfaces, but this anaerobic coccus is also an important opportunistic pathogen. SufA was the firstF. magnaproteinase to be isolated and characterized. Many bacterial pathogens interfere with different steps of blood coagulation, and here we describe how purified SufA efficiently and specifically cleaves fibrinogen in human plasma. SufA is both secreted byF. magnaand associated with the bacterial surface. Successful gene targeting has previously not been performed in anaerobic cocci, but in order to study the role of the SufA that is present at the bacterial surface, we constructed anF. magnamutant that expresses a truncated SufA lacking proteolytic activity. In contrast to wild-type bacteria that delayed the coagulation of human plasma, mutant bacteria had no such effect. Wild-type and mutant bacteria adhered to keratinocytes equally well, but in a plasma environment only wild-type bacteria blocked the formation of fibrin networks surrounding adherent bacteria. The effective cleavage of fibrinogen by SufA suggests that the interference with fibrin network formation represents an adaptive mechanism ofF. magnawith potential implications also for pathogenicity.
Involvement of the oscA gene in the sulphur starvation response and in Cr(VI) resistance in Pseudomonas corrugata 28
Authors: Viti Carlo , Decorosi Francesca , Mini Annalisa , Tatti Enrico , Giovannetti Luciana
Published: December 2008

Pseudomonas corrugata28 is a Cr(VI)-hyper-resistant bacterium. A Cr(VI)-sensitive mutant was obtained by insertional mutagenesis using EZ-Tn5Tnp. The mutant strain was impaired in a gene, here namedoscA(organosulphurcompounds), which encoded a hypothetical small protein of unknown function. The gene was located upstream of a gene cluster that encodes the components of the sulphate ABC transporter, and it formed a transcriptional unit withsbp, which encoded the periplasmic binding protein of the transporter. TheoscA–sbptranscriptional unit was strongly and quickly overexpressed after chromate exposure, suggesting the involvement ofoscAin chromate resistance, which was further confirmed by means of a complementation experiment. Phenotype MicroArray (PM) analysis made it possible to assay 1536 phenotypes and also indicated that theoscAgene was involved in the utilization of organosulphur compounds as a sole source of sulphur. This is believed to be the first evidence thatoscAplays a role in activating a sulphur starvation response, which is required to cope with oxidative stress induced by chromate.
Comparative EST analysis of a Zoophthora radicans isolate derived from Pieris brassicae and an isogenic strain adapted to Plutella xylostella
Authors: Xu J. , Baldwin D. , Kindrachuk C. , Hegedus D. D.
Published: December 2008

Zoophthora radicansis an entomopathogenic fungus with the potential to be used as an insect biological control agent. To better understand the mechanisms used byZ. radicansto infect different hosts, we generated expressed sequence tag (EST) datasets from aZ. radicansstrain originally isolated fromPieris brassicae, and an isogenic strain passaged throughPlutella xylostella. In total, 1839 ESTs were generated which clustered into 466 contigs and 433 singletons to provide a set of 899 unique sequences. Approximately 85 % of the ESTs were significantly similar (E≤e−03) to other fungal genes, of which 69.6 % encoded proteins with a reported function. Proteins involved in protein synthesis and metabolism were encoded by 38.3 % of the ESTs, while 26.3 % encoded proteins involved in cell-cycle regulation, DNA synthesis, protein fate, transport, cell defence, transcription and RNA synthesis, and 4.9 % encoded proteins associated with cellular transport, signal transduction, control of cellular organization and cell-wall degradation. Several proteinases, including aspartic proteinases, trypsins, trypsin-like serine proteases and metalloproteases, with the potential to degrade insect cuticle were expressed by the two isolates.
The Na+-translocating NADH : ubiquinone oxidoreductase of Azotobacter vinelandii negatively regulates alginate synthesis
Authors: Núñez Cinthia , Bogachev Alexander V. , Guzmán Gabriel , Tello Isaac , Guzmán Josefina , Espín Guadalupe
Published: December 2008

Azotobacter vinelandiiis a nitrogen-fixing soil bacterium that produces the exopolysaccharide alginate. In this report we describe the isolation and characterization ofA. vinelandiistrain GG4, which carries annqrE : : Tn5mutation resulting in alginate overproduction. ThenqrEgene encodes a subunit of the Na+-translocating NADH : ubiquinone oxidoreductase (Na+-NQR). As expected, Na+-NQR activity was abolished in mutant GG4. When this strain was complemented with thenqrEFgenes this activity was restored and alginate production was reduced to wild-type levels. Na+-NQR may be the main sodium pump ofA. vinelandiiunder the conditions tested (∼2 mM Na+) since no Na+/H+-antiporter activity was detected. Collectively our results indicate that inA. vinelandiithe lack of Na+-NQR activity caused the absence of a transmembrane Na+gradient and an increase in alginate production.
Identification of iron-responsive proteins expressed by Chlamydia trachomatis reticulate bodies during intracellular growth
Authors: Dill Brian D. , Dessus-Babus Sophie , Raulston Jane E.
Published: December 2008

The obligate intracellular bacterium Chlamydia trachomatis serovar E is the most prevalent cause of bacterial sexually transmitted disease. With an established requirement for iron, the developmental cycle arrests at the intracellular reticulate body stage during iron restriction, resulting in a phenomenon termed persistence. Persistence has implications in natural infections for altered expression of virulence factors and antigens, in addition to a potential role in producing chronic infection. In this study, chlamydial proteins in iron-restricted, infected HEC-1B cells were radiolabelled during mid-developmental cycle growth, harvested, and separated using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Of ∼250 radiolabelled protein species visualized, densitometric analysis revealed 25 proteins that increased in expression under iron restriction compared to iron-sufficient control samples; ten protein species identified by mass spectrometry are involved in the oxidative damage response (alkyl hydroperoxide reductase, 6-phosphogluconolactonase and acyl carrier protein synthase), transcription (RNA polymerase subunit alpha and transcription anti-termination factors NusA and NusG), protein modification (peptide deformylase and trigger factor), and virulence (Chlamydia protein associating with death domains, CADD). Transcript-level expression patterns of ahpC, devB, cadd, fabF and ct538 were measured by quantitative RT-PCR throughout the developmental cycle, and each gene examined demonstrated a significant but small mid-cycle increase in transcript level in iron-restricted cultures compared to iron-replete controls. Taken together, these data suggest that the primary response of chlamydiae to reduced iron availability is to increase expression of proteins involved in protection against oxidative damage via iron-catalysed generation of reactive oxygen species and adaptation to stress by increasing expression of transcriptional machinery and other stress-responsive proteins.
Pathway for H2O2 and O2 detoxification in Clostridium acetobutylicum
Authors: Riebe Oliver , Fischer Ralf-Jörg , Wampler David A. , Kurtz Donald M. , Bahl Hubert
Published: December 2008

An unusual non-haem diiron protein, reverse rubrerythrin (revRbr), is known to be massively upregulated in response to oxidative stress in the strictly anaerobic bacterium Clostridium acetobutylicum. In the present study both in vivo and in vitro results demonstrate an H2O2 and O2 detoxification pathway in C. acetobutylicum involving revRbr, rubredoxin (Rd) and NADH : rubredoxin oxidoreductase (NROR). RevRbr exhibited both NADH peroxidase (NADH : H2O2 oxidoreductase) and NADH oxidase (NADH : O2 oxidoreductase) activities in in vitro assays using NROR as the electron-transfer intermediary from NADH to revRbr. Rd increased the NADH consumption rate by serving as an intermediary electron-transfer shuttle between NROR and revRbr. While H2O2 was found to be the preferred substrate for revRbr, its relative oxidase activity was found to be significantly higher than that reported for other Rbrs. A revRbr-overexpressing strain of C. acetobutylicum showed significantly increased tolerance to H2O2 and O2 exposure. RevRbr thus appears to protect C. acetobutylicum against oxidative stress by functioning as the terminal component of an NADH peroxidase and NADH oxidase.
A phenotypic microarray analysis of a Streptococcus mutans liaS mutant
Authors: Zhang Jiaqin , Biswas Indranil
Published: December 2008

Streptococcus mutans, a biofilm-forming Gram-positive bacterium that resides in the human oral cavity, is considered to be the primary aetiological agent of human dental caries. A cell-envelope stress-sensing histidine kinase, LiaS, is considered to be important for expression of virulence factors such as glucan-binding protein C and mutacin production. In this study, a liaS mutant was subjected to phenotypic microarray (PM) analysis of about 2000 phenotypes, including utilization of various carbon, nitrogen, phosphate and sulfur sources; osmolytes; metabolic inhibitors; and susceptibility to toxic compounds, including several types of antibiotics. Compared to the parental strain UA159, the liaS mutant strain (IBS148) was more tolerant to various inhibitors that target protein synthesis, DNA synthesis and cell-wall biosynthesis. Some of the key findings of the PM analysis were confirmed in independent growth studies and by using antibiotic discs and E-test strips for susceptibility testing.
Role of the Escherichia coli Hfq protein in GcvB regulation of oppA and dppA mRNAs
Authors: Pulvermacher Sarah C. , Stauffer Lorraine T. , Stauffer George V.
Published: December 2008

ThegcvBgene encodes a small non-translated RNA (referred to as GcvB) that regulatesoppAanddppA, two genes that encode periplasmic binding proteins for the oligopeptide and dipeptide transport systems. Hfq, an RNA chaperone protein, binds many small RNAs and is required for the small RNAs to regulate expression of their respective target genes. We showed that repression by GcvB ofdppA : : lacZandoppA : : phoAtranslational fusions is dependent upon Hfq. Double mutations ingcvBandhfqyielded similar expression levels ofdppA : : lacZandoppA : : phoAcompared withgcvBorhfqsingle mutations, suggesting that GcvB and Hfq repress by the same mechanism. The effect of Hfq is not through regulation of transcription ofgcvB. Hfq is known to increase the stability of some small RNAs and to facilitate the interactions between small RNAs and specific mRNAs. In the absence of Hfq, there is a marked decrease in the half-life of GcvB in cells grown in both Luria–Bertani broth and glucose minimal medium with glycine, suggesting that part of the role of Hfq is to stabilize GcvB. Overproduction of GcvB in wild-typeEscherichia coliresults in superrepression of adppA : : lacZfusion, but overproduction of GcvB in anhfqmutant does not result in significant repression of thedppA : : lacZfusion. These results suggest that Hfq also is likely required for GcvB–mRNA pairing.
Interaction of the mechanism-based inactivator acetylene with ammonia monooxygenase of Nitrosomonas europaea
Authors: Gilch Stefan , Vogel Manja , Lorenz Matthias W. , Meyer Ortwin , Schmidt Ingo
Published: December 2008

The ammonia monooxygenase (AMO) ofNitrosomonas europaeais a metalloenzyme that catalyses the oxidation of ammonia to hydroxylamine. We have identified histidine 191 of AmoA as the binding site for the oxidized mechanism-based inactivator acetylene. Binding of acetylene changed the molecular mass of His-191 from 155.15 to 197.2 Da (+42.05), providing evidence that acetylene was oxidized to ketene (CH2CO; 42.04 Da) which binds specifically to His-191. It must be assumed that His-191 is part of the acetylene-activating site in AMO or at least directly neighbours this site.
In Vitro Sumoylation of Recombinant Proteins and Subsequent Purification for Use in Enzymatic Assays
Authors: Vethantham Vasupradha , Manley James L.
Published: January 2009

INTRODUCTION

The sumoylation reaction is mechanistically similar to ubiquitination. It is ATP-dependent and in vitro can be completed in two steps using purified E1 (SAE1/SAE2), E2 (ubc9), and SUMO. Even without the inclusion of an E3 ligase, many substrates can be modified at the same lysines in vitro as in vivo. Here we describe a simplified in vitro sumoylation protocol using recombinant sumoylation substrate, E1, E2, SUMO, and an ATP-regenerating system. The modified substrate can then be repurified from the reaction mixture in a single step to be used in assays to assess the impact of sumoylation on enzymatic and/or other activities.