bluuebunny/crossref_metadata_2025 huggingface dataset:
Cloud condensation nucleus activity of secondary organic aerosol particles mixed with sulfate
Authors: King Stephanie M. , Rosenoern Thomas , Shilling John E. , Chen Qi , Martin Scot T.
Published: December 2007

The cloud condensation nucleus (CCN) activity of organic‐sulfate particles was investigated using a steady‐state environmental chamber. The organic component consisted of secondary organic aerosol (SOA) generated in the dark from 24 ± 2 ppb α‐pinene for conditions of 300 ± 5 ppb ozone, 40 ± 2% relative humidity, and 25 ± 1°C, with the organic mass loading in the chamber ranging from 23 to 37 μg m−3. CCN analysis was performed for 80‐ to 150‐nm particles having variable organic‐sulfate volume fractions, which were estimated from the diameter of the organic‐sulfate particle relative to that of the seed as well as independently from mass spectra. Critical supersaturation, which increased for greater SOA volume fraction and smaller particle diameter, was well predicted by a Köhler model having two components, one for ammonium sulfate and another for SOA. The entire data set could be successfully modeled by a single suite of effective chemical parameters for SOA. The results suggest that the effects of limited organic solubility in mixed SOA‐sulfate particles may be reliably omitted in the treatment of cloud droplet formation.
Magnetic characteristics of synthetic pseudo‐single‐domain and multi‐domain greigite (Fe3S4)
Authors: Chang Liao , Roberts Andrew P. , Muxworthy Adrian R. , Tang Yan , Chen Qianwang , Rowan Christopher J. , Liu Qingsong , Pruner Petr
Published: December 2007

We report the magnetic properties of pure synthetic pseudo‐single‐domain (PSD) and multi‐domain (MD) greigite and the grain size dependence of the magnetic properties of greigite for the first time. The dominantly PSD‐like and MD‐like behavior are demonstrated by hysteresis, first‐order reversal curve diagrams, low‐temperature cycling (LTC) of room temperature saturation isothermal remanent magnetization (SIRM) and low‐temperature SIRM warming curves. Variations in a range of magnetic properties clearly correlate with grain size. Characteristic PSD/MD behavior is preserved at low temperatures, which, coupled with the small decrease in remanence during warming, rule out the presence of substantial superparamagnetic behavior in the studied samples. LTC‐SIRM measurements indicate a continuous demagnetization of remanence during cooling. Knowledge of this expanded range of magnetic properties of greigite should be widely useful in environmental magnetic and paleomagnetic studies.
Concentration of H, Si, Cl, K, Fe, and Th in the low‐ and mid‐latitude regions of Mars
Authors: Boynton W. V. , Taylor G. J. , Evans L. G. , Reedy R. C. , Starr R. , Janes D. M. , Kerry K. E. , Drake D. M. , Kim K. J. , Williams R. M. S. , Crombie M. K. , Dohm J. M. , Baker V. , Metzger A. E. , Karunatillake S. , Keller J. M. , Newsom H. E. , Arnold J. R. , Brückner J. , Englert P. A. J. , Gasnault O. , Sprague A. L. , Mitrofanov I. , Squyres S. W. , Trombka J. I. , d'Uston L. , Wänke H. , Hamara D. K.
Published: December 2007

We report maps of the concentrations of H, Si, Cl, K, Fe, and Th as determined by the Gamma Ray Spectrometer (GRS) on board the 2001 Mars Odyssey Mission for ±∼45° latitudes. The procedures by which the spectra are processed to yield quantitative concentrations are described in detail. The concentrations of elements determined over the locations of the various Mars landers generally agree well with the lander values except for Fe, although the mean of the GRS Fe data agrees well with that of Martian meteorites. The water‐equivalent concentration of hydrogen by mass varies from about 1.5% to 7.5% (by mass) with the most enriched areas being near Apollinaris Patera and Arabia Terra. Cl shows a distribution similar to H over the surface except that the Cl content over Medusae Fossae is much greater than elsewhere. The map of Fe shows enrichment in the northern lowlands versus the southern highlands. Silicon shows only very modest variation over the surface with mass fractions ranging from 19% to 22% over most of the planet, though a significant depletion in Si is noted in a region west of Tharsis Montes and Olympus Mons where the Si content is as low as 18%. K and Th show a very similar pattern with depletions associated with young volcanic deposits and enrichments associated with the TES Surface Type‐2 material. It is noted that there appears to be no evidence of significant globally distributed thick dust deposits of uniform composition.
Thermal regime of dune‐covered sediments under gaining and losing water bodies
Authors: Cardenas M. Bayani , Wilson John L.
Published: December 2007

We investigate the effects of current–bed form induced flow and heat transport through permeable‐bottom sediments overlain by a marine or terrestrial water column that is gaining or losing deep groundwater. Heat transport is forced by the diel variation of temperature in the water column. The investigation utilizes sequentially coupled simulations of turbulent flow in the water column, and Darcy flow and heat transport in the sediments. The simulations address the question when, where, and by how much are diel water column temperature variations transmitted into sediments subjected to ambient‐groundwater discharge? This is crucial information for detecting, observing, and predicting temperature‐sensitive biogeochemical and ecological processes in the bottom sediments. When the groundwater gain or loss is small, it has no appreciable effect on temperatures in the sediments, which are controlled by heat conduction and current–bed form induced heat advection. As losing discharge increases, the temperature signal from the water column penetrates deeper into the sediments, with the largest temperature variations found under a downwelling zone along the stoss side of the bed form and damped temperature variations found near a narrow upwelling zone below the crest. Similar patterns are observed under gaining conditions, but with temperature variations penetrating to shallower depths; the interfacial exchange zone is diminished by upward movement of deep groundwater. Large gains or losses of deep groundwater prevent the formation of an interfacial exchange zone making heat transport almost vertically one‐dimensional. The sensitivity of the sediment‐thermal regime to hydrodynamic conditions increases with increasing water column current (Reynolds number) and with sediment permeability.
Axis-dependent anisotropy in protein unfolding from integrated nonequilibrium single-molecule experiments, analysis, and simulation
Authors: Nome Rene A. , Zhao Jason Ming , Hoff Wouter D. , Scherer Norbert F.
Published: December 2007

We present a comprehensive study that integrates experimental and theoretical nonequilibrium techniques to map energy landscapes along well defined pull-axis specific coordinates to elucidate mechanisms of protein unfolding. Single-molecule force-extension experiments along two different axes of photoactive yellow protein combined with nonequilibrium statistical mechanical analysis and atomistic simulation reveal energetic and mechanistic anisotropy. Steered molecular dynamics simulations and free-energy curves constructed from the experimental results reveal that unfolding along one axis exhibits a transition-state-like feature where six hydrogen bonds break simultaneously with weak interactions observed during further unfolding. The other axis exhibits a constant (unpeaked) force profile indicative of a noncooperative transition, with enthalpic (e.g., H-bond) interactions being broken throughout the unfolding process. Striking qualitative agreement was found between the force-extension curves derived from steered molecular dynamics calculations and the equilibrium free-energy curves obtained by Jarzynski–Hummer–Szabo analysis of the nonequilibrium work data. The anisotropy persists beyond pulling distances of more than twice the initial dimensions of the folded protein, indicating a rich energy landscape to the mechanically fully unfolded state. Our findings challenge the notion that cooperative unfolding is a universal feature in protein stability.
Learning from episodes of degradation and recovery in variable Australian rangelands
Authors: Stafford Smith D. Mark , McKeon Greg M. , Watson Ian W. , Henry Beverley K. , Stone Grant S. , Hall Wayne B. , Howden S. Mark
Published: December 2007

Land-change science emphasizes the intimate linkages between the human and environmental components of land management systems. Recent theoretical developments in drylands identify a small set of key principles that can guide the understanding of these linkages. Using these principles, a detailed study of seven major degradation episodes over the past century in Australian grazed rangelands was reanalyzed to show a common set of events: (
i
) good climatic and economic conditions for a period, leading to local and regional social responses of increasing stocking rates, setting the preconditions for rapid environmental collapse, followed by (
ii
) a major drought coupled with a fall in the market making destocking financially unattractive, further exacerbating the pressure on the environment; then (
iii
) permanent or temporary declines in grazing productivity, depending on follow-up seasons coupled again with market and social conditions. The analysis supports recent theoretical developments but shows that the establishment of environmental knowledge that is strictly local may be insufficient on its own for sustainable management. Learning systems based in a wider community are needed that combine local knowledge, formal research, and institutional support. It also illustrates how natural variability in the state of both ecological and social systems can interact to precipitate nonequilibrial change in each other, so that planning cannot be based only on average conditions. Indeed, it is this variability in both environment and social subsystems that hinders the local learning required to prevent collapse.
Agent-based modeling of deforestation in southern Yucatán, Mexico, and reforestation in the Midwest United States
Authors: Manson Steven M. , Evans Tom
Published: December 2007

We combine mixed-methods research with integrated agent-based modeling to understand land change and economic decision making in the United States and Mexico. This work demonstrates how sustainability science benefits from combining integrated agent-based modeling (which blends methods from the social, ecological, and information sciences) and mixed-methods research (which interleaves multiple approaches ranging from qualitative field research to quantitative laboratory experiments and interpretation of remotely sensed imagery). We test assumptions of utility-maximizing behavior in household-level landscape management in south-central Indiana, linking parcel data, land cover derived from aerial photography, and findings from laboratory experiments. We examine the role of uncertainty and limited information, preferences, differential demographic attributes, and past experience and future time horizons. We also use evolutionary programming to represent bounded rationality in agriculturalist households in the southern Yucatán of Mexico. This approach captures realistic rule of thumb strategies while identifying social and environmental factors in a manner similar to econometric models. These case studies highlight the role of computational models of decision making in land-change contexts and advance our understanding of decision making in general.
Combinatorics of feedback in cellular uptake and metabolism of small molecules
Authors: Krishna Sandeep , Semsey Szabolcs , Sneppen Kim
Published: December 2007

We analyze the connection between structure and function for regulatory motifs associated with cellular uptake and usage of small molecules. Based on the boolean logic of the feedback we suggest four classes: the
socialist
,
consumer
,
fashion
, and
collector
motifs. We find that the
socialist
motif is good for homeostasis of a useful but potentially poisonous molecule, whereas the
consumer
motif is optimal for nutrition molecules. Accordingly, examples of these motifs are found in, respectively, the iron homeostasis system in various organisms and in the uptake of sugar molecules in bacteria. The remaining two motifs have no obvious analogs in small molecule regulation, but we illustrate their behavior using analogies to fashion and obesity. These extreme motifs could inspire construction of synthetic systems that exhibit bistable, history-dependent states, and homeostasis of flux (rather than concentration).
Race, Neighbourhood Context and Perceptions of Injustice by the Police in Cincinnati
Authors: MacDonald John , Stokes Robert J. , Ridgeway Greg , Riley K. Jack
Published: December 2007

Research has long identified racial differences in perceptions of criminal injustice. Given that race is confounded with neighbourhood context, it remains unclear the extent to which individual or neighbourhood attributes explain racial differences in these perceptions. This paper advances research on racial differences in perceptions of unjust police practices in the US by relying on a survey of 3000 residents in 53 Cincinnati neighbourhoods. A propensity score weighting approach is used to identify a model by which Whites and Blacks living in similar neighbourhood environments can be compared with each other. The results demonstrate that race remains a significant predictor of perceptions of unjust police practices, even after taking into account the ecological structuring of neighbourhoods and their perceived environmental context. These findings suggest that racial consciousness with regard to perceived injustices by the police is not purely a condition of personal or structural disadvantage. The implications of these findings for police reform efforts to mend minority relations in urban cities are discussed.
Human Capital, Higher Education and Graduate Migration: An Analysis of Scottish and Welsh Students
Authors: Faggian Alessandra , McCann Philip , Sheppard Stephen
Published: December 2007

This paper reports on a model of the sequential migration behaviour of some 76 000 Scottish and Welsh students, from their domicile location to the location of their higher education and on to their employment location. A logit model methodology is employed to analyse the choice of the location of the university attended, whether inside or outside Scotland or Wales. Then, within a GIS framework, migration-on-migration correlations and elasticities are estimated in order to identify the mobility effects of human capital acquisition. The results confirm the DaVanzo hypothesis that subsequent migration is related to previous migration and also the Sjaastad—Becker hypothesis that higher human capital individuals are more geographically mobile. However, there are institutional differences between the two countries which mean that the mobility effects of human capital acquisition have to be interpreted carefully in the light of other economic, geographical and social influences.
Inhibition of Proteasome Activity Impairs Centrosome-dependent Microtubule Nucleation and Organization
Authors: Didier Christine , Merdes Andreas , Gairin Jean-Edouard , Jabrane-Ferrat Nabila
Published: December 2007

Centrosomes are dynamic organelles that consist of a pair of cylindrical centrioles, surrounded by pericentriolar material. The pericentriolar material contains factors that are involved in microtubule nucleation and organization, and its recruitment varies during the cell cycle. We report here that proteasome inhibition in HeLa cells induces the accumulation of several proteins at the pericentriolar material, including gamma-tubulin, GCP4, NEDD1, ninein, pericentrin, dynactin, and PCM-1. The effect of proteasome inhibition on centrosome proteins does not require intact microtubules and is reversed after removal of proteasome inhibitors. This accrual of centrosome proteins is paralleled by accumulation of ubiquitin in the same area and increased polyubiquitylation of nonsoluble gamma-tubulin. Cells that have accumulated centrosome proteins in response to proteasome inhibition are impaired in microtubule aster formation. Our data point toward a role of the proteasome in the turnover of centrosome proteins, to maintain proper centrosome function.
A Novel Regulatory Mechanism of Myosin Light Chain Phosphorylation via Binding of 14-3-3 to Myosin Phosphatase
Authors: Koga Yasuhiko , Ikebe Mitsuo
Published: December 2007

Myosin II phosphorylation–dependent cell motile events are regulated by myosin light-chain (MLC) kinase and MLC phosphatase (MLCP). Recent studies have revealed myosin phosphatase targeting subunit (MYPT1), a myosin-binding subunit of MLCP, plays a critical role in MLCP regulation. Here we report the new regulatory mechanism of MLCP via the interaction between 14-3-3 and MYPT1. The binding of 14-3-3β to MYPT1 diminished the direct binding between MYPT1 and myosin II, and 14-3-3β overexpression abolished MYPT1 localization at stress fiber. Furthermore, 14-3-3β inhibited MLCP holoenzyme activity via the interaction with MYPT1. Consistently, 14-3-3β overexpression increased myosin II phosphorylation in cells. We found that MYPT1 phosphorylation at Ser472 was critical for the binding to 14-3-3. Epidermal growth factor (EGF) stimulation increased both Ser472 phosphorylation and the binding of MYPT1-14-3-3. Rho-kinase inhibitor inhibited the EGF-induced Ser472 phosphorylation and the binding of MYPT1-14-3-3. Rho-kinase specific siRNA also decreased EGF-induced Ser472 phosphorylation correlated with the decrease in MLC phosphorylation. The present study revealed a new RhoA/Rho-kinase–dependent regulatory mechanism of myosin II phosphorylation by 14-3-3 that dissociates MLCP from myosin II and attenuates MLCP activity.
Transforming Growth Factor β Controls the Directional Migration of Hepatocyte Cohorts by Modulating Their Adhesion to Fibronectin
Authors: Binamé Fabien , Lassus Patrice , Hibner Urszula
Published: December 2007

Transforming growth factor β (TGF-β) has a strong impact on liver development and physiopathology, exercised through its pleiotropic effects on growth, differentiation, survival, and migration. When exposed to TGF-β, the mhAT3F cells, immortalized, highly differentiated hepatocytes, maintained their epithelial morphology and underwent dramatic alterations of adhesion, leading to partial or complete detachment from a culture plate, followed by readhesion and spreading. These alterations of adhesive behavior were caused by sequential changes in expression of the α5β1 integrin and of its ligand, the fibronectin. The altered specificity of anchorage to the extracellular matrix gave rise to changes in cells' collective motility: cohorts adhering to fibronectin maintained a persistent, directional motility, with ezrin-rich pathfinder cells protruding from the tips of the cohorts. The absence of adhesion to fibronectin prevented the appearance of polarized pathfinders and lead to random, oscillatory motility. Our data suggest a novel role for TGF-β in the control of collective migration of epithelial cohorts.
Solutions to the Eshelby conjectures
Authors: Liu L.P
Published: December 2007

We present solutions to the Eshelby conjectures based on a variational inequality. We first discuss the meanings of Eshelby's original statement. By Fourier analysis, we establish the connection between the homogeneous Eshelby inclusion problem and the classic Newtonian potential problem. We then proceed to the solutions of the Eshelby conjectures. Under some hypothesis on the material properties and restricted to connected inclusions with Lipschitz boundaries, we show that one version of the Eshelby conjectures is valid in all dimensions and the other version is valid in two dimensions. We also show the existence of multiply connected inclusions in all dimensions and the existence of non-ellipsoidal connected inclusions in three and higher dimensions such that, in physical terms and in the context of elasticity, some uniform eigenstress of the inclusion induces uniform strain on the inclusion. We numerically calculate these special inclusions based on the finite-element method.
Compatibility counts: MHC-associated mate choice in a wild promiscuous primate
Authors: Schwensow Nina , Eberle Manfred , Sommer Simone
Published: December 2007

The mechanisms and temporal aspects of mate choice according to genetic constitution are still puzzling. Recent studies indicate that fitness is positively related to diversity in immune genes (MHC). Both sexes should therefore choose mates of high genetic quality and/or compatibility. However, studies addressing the role of MHC diversity in pre- and post-copulatory mate choice decisions in wild-living animals are few. We investigated the impact of MHC constitution and of neutral microsatellite variability on pre- and post-copulatory mate choice in both sexes in a wild population of a promiscuous primate, the grey mouse lemur (Microcebus murinus). There was no support for pre-copulatory male or female mate choice, but our data indicate post-copulatory mate choice that is associated with genetic constitution. Fathers had a higher number of MHC supertypes different from those of the mother than randomly assigned males. Fathers also had a higher amino acid distance to the females' MHC as well as a higher total number of MHC supertypes and a higher degree of microsatellite heterozygosity than randomly assigned males. Female cryptic choice may be the underlying mechanism that operates towards an optimization of the genetic constitution of offspring. This is the first study that provides support for the importance of the MHC constitution in post-copulatory mate choice in non-human primates.
Diel variation in a dynamic sexual display and its association with female mate-searching behaviour
Authors: Jacot Alain , Scheuber Hannes , Holzer Barbara , Otti Oliver , Brinkhof Martin W.G
Published: December 2007

Dynamic sexual signals often show a diel rhythm and may vary substantially with time of day. Diel and short-term fluctuations in such sexual signals pose a puzzle for condition capture models of mate choice, which assume a female preference for male traits that reliably reflect a male's quality. Here we experimentally manipulated the food supply of individual male field crickets
Gryllus campestris
in their natural habitat in two consecutive seasons to determine (i) the effect of male nutritional condition on the fine-scaled variation of diel investment in acoustic signalling and (ii) the temporal association between the diel variation in male signalling and female mate-searching behaviour. Overall food-supplemented males signalled more often, but the effect was only visible during the daytime. In the evening and the night, signal output was still high but the time spent signalling was unrelated to a male's nutritional condition. Females' mate-searching behaviour also showed a diel rhythm with peak activity during the afternoon, when differences among calling males were highest, and where signal output reliably reflects male quality. These findings suggest that males differing in nutritional condition may optimize their investment in signalling in relation to time of day as to maximize mating success.
More ‘altruistic’ punishment in larger societies
Authors: Marlowe Frank W , Berbesque J. Colette , Barr Abigail , Barrett Clark , Bolyanatz Alexander , Cardenas Juan Camilo , Ensminger Jean , Gurven Michael , Gwako Edwins , Henrich Joseph , Henrich Natalie , Lesorogol Carolyn , McElreath Richard , Tracer David
Published: December 2007

If individuals will cooperate with cooperators, and punish non-cooperators even at a cost to themselves, then this strong reciprocity could minimize the cheating that undermines cooperation. Based upon numerous economic experiments, some have proposed that human cooperation is explained by strong reciprocity and norm enforcement. Second-party punishment is when you punish someone who defected on you; third-party punishment is when you punish someone who defected on someone else. Third-party punishment is an effective way to enforce the norms of strong reciprocity and promote cooperation. Here we present new results that expand on a previous report from a large cross-cultural project. This project has already shown that there is considerable cross-cultural variation in punishment and cooperation. Here we test the hypothesis that population size (and complexity) predicts the level of third-party punishment. Our results show that people in larger, more complex societies engage in significantly more third-party punishment than people in small-scale societies.
Sexual selection mediated by the thermoregulatory effects of male colour pattern in the ambush bugPhymata americana
Authors: Punzalan David , Rodd F. Helen , Rowe Locke
Published: December 2007

Sexual dimorphism in coloration is a taxonomically widespread phenomenon often attributed to sexual selection on visual signals. However, the ambush bugPhymata americanaexhibits sexual dimorphism in coloration that has no apparent signalling function. Here we provide evidence that colour pattern in this species influences male mating success indirectly through its effect on thermoregulation. We demonstrate, using experimental manipulation, that individuals with dark colour pattern achieve higher thoracic temperatures under illumination. We also show that dark colour pattern predicted mate-searching success but only under thermally challenging conditions (i.e. cool ambient temperature). As far as we are aware, this is the first study to provide evidence that sexual dimorphism can be accounted for by sexual selection on thermoregulatory performance.
Primary and Secondary Infections ofMacaca fascicularisMonkeys with Asian and American Genotypes of Dengue Virus 2
Authors: Bernardo Lidice , Izquierdo Alienys , Prado Irina , Rosario Delfina , Alvarez Mayling , Santana Emidalys , Castro Jorge , Martínez Rafael , Rodríguez Rosmari , Morier Luis , Guillén Gerardo , Guzmán María G.
Published: December 2007

The goal of this study was to compare the immune response and the protection capacity induced by the dengue virus 2 (DENV-2) American and Asian genotypes inMacaca fascicularismonkeys. Animals were infected with American or Asian DENV-2 strains and challenged 1 year later with a DENV-2 Asian genotype strain. The viremia and monkey antibody levels were similar for the different strains after primary and secondary infection; however, the functionality of the antibody response was different. A limited viral replication was demonstrated after the secondary infection in all the monkeys. No virus was isolated in tissue culture, while reverse transcription-PCR showed a late positive reaction in four of five challenged monkeys. The immunoglobulin M response pattern and the detection of antibodies to specific proteins by Western blotting supported the protection data. Despite the demonstration of the protective effect after homologous challenge, a strong anamnestic antibody response was observed.
Influence of Maternal Antibodies on Efficacy of Porcine Circovirus Type 2 (PCV2) Vaccination To Protect Pigs from Experimental Infection with PCV2
Authors: Opriessnig T. , Patterson A. R. , Elsener J. , Meng X. J. , Halbur P. G.
Published: December 2007

Due to the ubiquitous nature of porcine circovirus type 2 (PCV2) in the pig population and the increasing use of PCV2 vaccines in breeding herds, the majority of dams have been exposed to field PCV2 or PCV2 vaccines, resulting in piglets with varied levels of passively acquired PCV2 maternal antibodies. The objective of the current research was to investigate the influence of passively acquired anti-PCV2 antibodies on PCV2 vaccine efficacy. Sixty 26-day-old pigs were divided into four groups: vaccinated pigs with no maternal PCV2 antibodies at the time of vaccination (VAC-NEG;n= 9), vaccinated pigs with maternal PCV2 antibodies at the time of vaccination (VAC-POS;n= 21), nonvaccinated pigs with no maternal antibodies at the time of challenge (NVAC-CNEG;n= 15), and nonvaccinated pigs with maternal antibodies at the time of challenge (NVAC-CPOS;n= 15). Vaccinations and challenges were performed on trial days 0 and 28, respectively, according to group designation. The pigs were monitored for clinical signs of disease daily and weighed weekly, and blood was collected weekly. All pigs were necropsied on trial day 49, and tissues were evaluated for macroscopic and microscopic lesions. Serum was evaluated using PCV2 immunoglobulin G (IgG) and PCV2 IgM enzyme-linked immunosorbent assays, quantitative PCV2 PCR, and a serum PCV2 neutralizing antibody test. In comparison to NVAC-CPOS pigs, VAC-POS animals had significantly (P< 0.01) less severe microscopic PCV2-associated lymphoid lesions and significantly (P< 0.04) reduced PCV2 genomic copies in serum following PCV2 challenge. These results indicate that vaccination with Suvaxyn PCV2 One Dose reduces viremia and prevents microscopic lesions associated with PCV2 in the presence of maternal antibodies.
Evaluation of Commercial Antisera for
Salmonella
Serotyping
Authors: Schrader Kimmi N. , Fernandez-Castro Ali , Cheung Wendy K. W. , Crandall Claudia M. , Abbott Sharon L.
Published: December 2007

We compared a set of commercial
Salmonella
somatic and flagellar serotyping antisera to in-house-prepared antisera from the Microbial Diseases Laboratory, California Department of Public Health, using 327
Salmonella enterica
strains belonging to subgroups I, II, IIIa, IIIb, and IV. The sensitivities of Denka Seiken (Tokyo, Japan) somatic and flagellar antisera (using a tube agglutination assay) were 94.0% and 99.2%, respectively, and the specificity was 100% for both sets of sera. Polyvalent O and O1 antiserum sensitivity and specificity were >90%, with the exception of polyvalent O1 antiserum, for which sensitivity was 88.9%. When Denka Seiken flagellar antisera were used in a slide agglutination assay, the sensitivity and accuracy dropped to 88.9% and the specificity fell to 91%. Overall, Denka Seiken commercial antisera performed very well and, together with the comprehensive range of factors available, offer laboratories quality reagents suitable for serotyping strains of salmonellae.
Molecular Epidemiology of Extended-Spectrum β-Lactamases among
Escherichia coli
Isolates Collected in a Swedish Hospital and Its Associated Health Care Facilities from 2001 to 2006
Authors: Fang Hong , Ataker Ferda , Hedin Göran , Dornbusch Kathrine
Published: December 2007

The genetic characteristics and molecular epidemiology of extended-spectrum β-lactamases (ESBLs) among
Escherichia coli
isolates were investigated at a general hospital and its associated health care facilities in Stockholm, Sweden, during the period from 2001 to 2006. Of 87 consecutive nonduplicate ESBL-positive isolates, 80 isolates encoded CTX-M-type ESBLs, 64 of which were group 1 enzymes. TEM-type and OXA-type β-lactamases were encoded in 63 and 59% of the ESBL isolates, respectively. Pulsed-field gel electrophoresis (PFGE) analysis revealed 40 different pulsotypes, consisting of 11 clones accounting for 66% of all isolates, and 29 unique patterns. Moreover, of the 11 clones, clones 1 and 4 comprised half of the clonally related isolates (28 of 57). Clone 1 was a persistent endemic clone in the area throughout the years, and clone 4 emerged in 2003. However, in recent years, clone 1 isolates were no longer predominant and were gradually replaced by new emerging strains. Concerning β-lactamase gene profiles in relation to PFGE pulsotypes, clone-related
bla
profiles were observed in certain clones, while in most cases different
bla
profiles could be observed in the same clone, and the same
bla
profile could be present in different clones. The molecular epidemiology of ESBL-positive
E. coli
in the area shows shifts in predominant strains and increased clonal diversity over time. The study also indicated that both clonal spread of epidemic strains and transfer of transposable genetic elements might contribute to the proliferation of ESBLs.
Selection of a Surrogate Agent (Fluconazole or Voriconazole) for Initial Susceptibility Testing of Posaconazole against
Candida
spp.: Results from a Global Antifungal Surveillance Program
Authors: Pfaller M. A. , Messer S. A. , Boyken L. , Tendolkar S. , Hollis R. J. , Diekema D. J.
Published: December 2007

There are currently no FDA-approved broth microdilution antifungal susceptibility testing products or interpretive breakpoints for susceptibility testing of the new triazole posaconazole. Fluconazole and voriconazole are in the same triazole class as posaconazole, have CLSI-approved interpretive MIC breakpoints, and are available on some commercially available MIC panels. We investigated whether one or both of these agents may be useful as a surrogate marker for posaconazole susceptibility. Fluconazole, voriconazole, and posaconazole MIC results for 10,807 isolates of
Candida
spp. were analyzed to validate a potential surrogate marker for posaconazole activity against indicated species. For illustrative purposes, we applied the voriconazole MIC breakpoints to posaconazole (susceptible, ≤1 μg/ml; susceptible dose dependent, 2 μg/ml; resistant, ≥4 μg/ml) and compared these MIC results and categorical interpretations with those of fluconazole and voriconazole by using regression statistics and categorical agreement. For all 10,807 isolates, the absolute categorical agreement was 91.1% (0.1% very major errors [VME], 1.2% major errors [ME], and 7.6% minor errors [M]) using fluconazole as the surrogate marker and 97.7% (0.3% VME 0.1% ME, and 1.9% M) using voriconazole as the surrogate. The results with fluconazole improved to a categorical agreement of 93.7% (0.1% VME, 0.2% ME, and 6.0% M) when results for
Candida krusei
(not indicated for fluconazole testing) were omitted. Either fluconazole or voriconazole MIC results may serve as surrogate markers to predict the susceptibility of
Candida
spp. to posaconazole.
Definition of the Minimal
cis
-Acting Sequences Necessary for Genome Maturation of the Herpesvirus Murine Cytomegalovirus
Authors: Wang Jian Ben , Nixon Daniel E. , McVoy Michael A.
Published: December 2007

Herpesvirus DNA replication proceeds via concatemeric replicative intermediates that are comprised of head-to-tail-linked genomes. Genome maturation is carried out by the terminase, a protein complex that mediates both insertion of concatemer DNA into capsids and its subsequent cleavage to release genomes within these capsids. This cleavage is sequence specific, but the governing
cis
-acting DNA sequences are only partially characterized. Two highly conserved motifs called
pac1
and
pac2
lie near the ends of herpesvirus genomes and are known to be critical for genome maturation. However, the potential importance of other sequences has not been fully investigated. We have undertaken to define all of the sequences necessary for efficient genome maturation for a herpesvirus by inserting ectopic cleavage sites into the murine cytomegalovirus genome and assessing their ability to mediate genome maturation. A combination of deletion and substitution mutations revealed that the minimal cleavage site is large (∼180 bp) and complex. Sequences distal of
pac1
(relative to the point of cleavage) were dispensable, suggesting that
pac1
may be the sole
cis
-acting element on this side of the cleavage site. In contrast, a region distal to
pac2
up to 150 bp from the point of cleavage was essential. Scanning substitutions revealed that the
pac2
side of the cleavage site is complex and may contain multiple
cis
-acting sequence elements in addition to
pac2
. These results should facilitate the identification of
trans
-acting factors that bind to these elements and the elucidation of their functions. Such information will be critical for understanding the molecular basis of this complex process.
Differential Role of Gamma Interferon in Inhibiting Pulmonary Eosinophilia and Exacerbating Systemic Disease in Fusion Protein-Immunized Mice Undergoing Challenge Infection with Respiratory Syncytial Virus
Authors: Castilow Elaine M. , Olson Matthew R. , Meyerholz David K. , Varga Steven M.
Published: December 2007

Secondary exposure to respiratory syncytial virus (RSV) can lead to immunopathology and enhanced disease in vaccinated individuals. Vaccination with individual RSV proteins influences the type of secondary RSV-specific immune response that develops upon challenge RSV infection, as well as the extent of immunopathology. RSV-specific memory CD4 T cells can directly contribute to immunopathology through their cytokine production. Immunization of BALB/c mice with a recombinant vaccinia virus (vv) expressing the attachment (G) protein of RSV results in pulmonary eosinophilia upon RSV challenge, whereas immunization of mice with a vv expressing the fusion (F) protein does not. We analyzed the CD4 T-cell response to an I-Ed-restricted CD4 T-cell epitope within the F protein of RSV corresponding to amino acids 51 to 66 in an effort to better understand the similarities and differences in the immune response elicited by the G versus the F protein. Vaccination with the G protein induces a mixture of RSV G-specific Th1 and Th2 cells with a restricted T-cell receptor repertoire. In contrast, we demonstrate here that immunization with the F protein elicits a broad repertoire of RSV F-specific CD4 T cells that predominantly exhibit a Th1 phenotype. However, in the absence of gamma interferon (IFN-γ), RSV F51-66-specific CD4 T cells secreted interleukin-5, and mice developed pulmonary eosinophilia after RSV challenge. IFN-γ-deficient mice exhibited decreased weight loss compared to wild-type controls, suggesting that IFN-γ exacerbates systemic disease. These data demonstrate that IFN-γ can have both beneficial and detrimental effects during a secondary RSV infection.
Human Immunodeficiency Virus Type 1 Vpr Inhibits Axonal Outgrowth through Induction of Mitochondrial Dysfunction
Authors: Kitayama Hiroko , Miura Yoshiharu , Ando Yoshinori , Hoshino Shigeki , Ishizaka Yukihito , Koyanagi Yoshio
Published: December 2007

Human immunodeficiency virus type 1 (HIV-1)-infected macrophages damage mature neurons in the brain, although their effect on neuronal development has not been clarified. In this study, we show that HIV-1-infected macrophages produce factors that impair the development of neuronal precursor cells and that soluble viral protein R (Vpr) is one of the factors that has the ability to suppress axonal growth. Cell biological analysis revealed that extracellularly administered recombinant Vpr (rVpr) clearly accumulated in mitochondria where a Vpr-binding protein adenine nucleotide translocator localizes and also decreased the mitochondrial membrane potential, which led to ATP synthesis. The depletion of ATP synthesis reduced the transportation of mitochondria within neurites. This mitochondrial dysfunction inhibited axonal growth even when the frequency of apoptosis was not significant. We also found that point mutations of arginine (R) residues to alanine (A) residues at positions 73, 77, and 80 rendered rVpr incapable of causing mitochondrial membrane depolarization and axonal growth inhibition. Moreover, the Vpr-induced inhibition was suppressed after treatment with a ubiquinone analogue (ubiquinone-10). Our results suggest that soluble Vpr is a major viral factor that causes a disturbance in neuronal development through the induction of mitochondrial dysfunction. Since ubiquinone-10 protects the neuronal plasticity in vitro, it may be a therapeutic agent that can offer defense against HIV-1-associated neurological disease.
Human Immunodeficiency Virus Type 1 Nef Recruits the Guanine Exchange Factor Vav1 via an Unexpected Interface into Plasma Membrane Microdomains for Association with p21-Activated Kinase 2 Activity
Authors: Rauch Susanne , Pulkkinen Kati , Saksela Kalle , Fackler Oliver T.
Published: December 2007

Alterations of T-cell receptor signaling by human immunodeficiency virus type 1 (HIV-1) Nef involve its association with a highly active subpopulation of p21-activated kinase 2 (PAK2) within a dynamic signalosome assembled in detergent-insoluble membrane microdomains. Nef-PAK2 complexes contain the GTPases Rac and Cdc42 as well as a factor providing guanine nucleotide exchange factor (GEF) activity for Rac/Cdc42. However, the identity of this GEF has remained controversial. Previous studies suggested the association of Nef with at least three independent GEFs, Vav, DOCK2/ELMO1, and βPix. Here we used a broad panel of approaches to address which of these GEFs is involved in the functional interaction of Nef with PAK2 activity. Biochemical fractionation and confocal microscopy revealed that Nef recruits Vav1, but not DOCK2/ELMO1 or βPix, to membrane microdomains. Transient RNAi knockdown, analysis of cell lines defective for expression of Vav1 or DOCK2 as well as use of a βPix binding-deficient PAK2 variant confirmed a role for Vav1 but not DOCK2 or βPix in Nef's association with PAK2 activity. Nef-mediated microdomain recruitment of Vav1 occurred independently of the Src homology 3 domain binding PxxP motif, which is known to connect Nef to many cellular signaling processes. Instead, a recently described protein interaction surface surrounding Nef residue F195 was identified as critical for Nef-mediated raft recruitment of Vav1. These results identify Vav1 as a relevant component of the Nef-PAK2 signalosome and provide a molecular basis for the role of F195 in formation of a catalytically active Nef-PAK2 complex.
Structure of Antibody-Neutralized Murine Norovirus and Unexpected Differences from Viruslike Particles
Authors: Katpally Umesh , Wobus Christiane E. , Dryden Kelly , Virgin Herbert W. , Smith Thomas J.
Published: December 2007

Noroviruses (family
Caliciviridae
) are the major cause of epidemic nonbacterial gastroenteritis in humans, but the mechanism of antibody neutralization is unknown and no structure of an infectious virion has been reported. Murine norovirus (MNV) is the only norovirus that can be grown in tissue culture, studied in an animal model, and reverse engineered via an infectious clone and to which neutralizing antibodies have been isolated. Presented here are the cryoelectron microscopy structures of an MNV virion and the virion in complex with neutralizing Fab fragments. The most striking differences between MNV and previous calicivirus structures are that the protruding domain is lifted off the shell domain by ∼16Å and rotated ∼40° in a clockwise fashion and forms new interactions at the P1 base that create a cagelike structure engulfing the shell domains. Neutralizing Fab fragments cover the outer surface of each copy of the capsid protein P2 domains without causing any apparent conformational changes. These unique features of MNV suggest that at least some caliciviruses undergo a capsid maturation process akin to that observed with other plant and bacterial viruses.
The Glycoprotein and the Matrix Protein of Rabies Virus Affect Pathogenicity by Regulating Viral Replication and Facilitating Cell-to-Cell Spread
Authors: Pulmanausahakul Rojjanaporn , Li Jianwei , Schnell Matthias J. , Dietzschold Bernhard
Published: December 2007

While the glycoprotein (G) of rabies virus (RV) is known to play a predominant role in the pathogenesis of rabies, the function of the RV matrix protein (M) in RV pathogenicity is not completely clear. To further investigate the roles of these proteins in viral pathogenicity, we constructed chimeric recombinant viruses by exchanging the G and M genes of the attenuated SN strain with those of the highly pathogenic SB strain. Infection of mice with these chimeric viruses revealed a significant increase in the pathogenicity of the SN strain bearing the RV G from the pathogenic SB strain. Moreover, the pathogenicity was further increased when both G and M from SB were introduced into SN. Interestingly, the replacement of the G or M gene or both in SN by the corresponding genes of SB was associated with a significant decrease in the rate of viral replication and viral RNA synthesis. In addition, a chimeric SN virus bearing both the M and G genes from SB exhibited more efficient cell-to-cell spread than a chimeric SN virus in which only the G gene was replaced. Together, these data indicate that both G and M play an important role in RV pathogenesis by regulating virus replication and facilitating cell-to-cell spread.
Single Intranasal Immunization with Recombinant Adenovirus-Based Vaccine Induces Protective Immunity against Respiratory Syncytial Virus Infection
Authors: Yu Jae-Rang , Kim Sol , Lee Jee-Boong , Chang Jun
Published: December 2007

Respiratory syncytial virus (RSV) is a major cause of severe lower respiratory tract disease in infancy and early childhood. Despite its importance as a pathogen, there is no licensed vaccine against RSV. The G glycoprotein of RSV, a major attachment protein, is a potentially important target for protective antiviral immune responses. Here, a recombinant replication-deficient adenovirus-based vaccine, rAd/3xG, expressing the soluble core domain of G glycoprotein (amino acids 130 to 230) engineered by codon optimization and tandem repetition for higher-level expression, was constructed and evaluated for its potential as an RSV vaccine in a murine model. A single intranasal immunization with rAd/3xG provided potent protection against RSV challenge which lasted for more than 10 weeks. Strong mucosal immunoglobulin A responses were also induced by a single intranasal immunization but not by intramuscular or oral administration of rAd/3xG. Interestingly, neither gamma interferon- nor interleukin-4-producing CD4 T cells directed to I-Ed-restricted epitope were detected in the lungs of rAd/3xG-immune mice upon challenge, whereas priming with vaccinia virus expressing RSV G (vvG) elicited strong Th1/Th2 mixed CD4 T-cell responses. Lung eosinophilia and vaccine-induced weight loss were significantly lower in the rAd/3xG-immune group than in the vvG-primed group. Together, our data demonstrate that a single intranasal administration of rAd/3xG elicits beneficial protective immunity and represents a promising vaccine regimen against RSV infection.
Petroleum and progress in geology
Authors: HEDBERG HOLLIS DOW
Published: December 2007

If W
illiam
S
mith
had lived in the 20th century, he might well have been a great petroleum geologist. Even in his time, at the turn of the 18th century, it was needs, similar to those of the present for heat, power and transportation that led him, through the surveying of coal mines and canals, into a geological career, and that made him one of the great contributors to the fundamentals of the petroleum geology which was to come only long after his time. Let us consider then, in what manner petroleum may have repaid, in part, the debt which it owes to William Smith and to other early pioneers in stratigraphy and related fields of geology.

In the midst of our aggressive search for new geological facts and our enthusiastic attempts at new geological hypotheses, it is perhaps well to step aside for a moment to appraise and evaluate some of the factors and influences which have helped to bring us to where we are in geology today. I am, therefore, pleased that the Council of the Geological Society has seen fit to encourage me in presenting, not the usual story of new research results, but rather an appreciation of the contributions to geology which have grown out of the quest for a particular and unique mineral resource.

We are living today in a brief and fleeting period of world history which may well be known as the Petroleum Age. We have had the Stone Age, the Bronze Age, the