bluuebunny/crossref_metadata_2025_split huggingface dataset:
New perspectives on viable microbial communities in low-biomass cleanroom environments
Authors: Vaishampayan Parag , Probst Alexander J , La Duc Myron T , Bargoma Emilee , Benardini James N , Andersen Gary L , Venkateswaran Kasthuri 
Published: October 2012

Abstract
The advent of phylogenetic DNA microarrays and high-throughput pyrosequencing technologies has dramatically increased the resolution and accuracy of detection of distinct microbial lineages in mixed microbial assemblages. Despite an expanding array of approaches for detecting microbes in a given sample, rapid and robust means of assessing the differential viability of these cells, as a function of phylogenetic lineage, remain elusive. In this study, pre-PCR propidium monoazide (PMA) treatment was coupled with downstream pyrosequencing and PhyloChip DNA microarray analyses to better understand the frequency, diversity and distribution of viable bacteria in spacecraft assembly cleanrooms. Sample fractions not treated with PMA, which were indicative of the presence of both live and dead cells, yielded a great abundance of highly diverse bacterial pyrosequences. In contrast, only 1% to 10% of all of the pyrosequencing reads, arising from a few robust bacterial lineages, originated from sample fractions that had been pre-treated with PMA. The results of PhyloChip analyses of PMA-treated and -untreated sample fractions were in agreement with those of pyrosequencing. The viable bacterial population detected in cleanrooms devoid of spacecraft hardware was far more diverse than that observed in cleanrooms that housed mission-critical spacecraft hardware. The latter was dominated by hardy, robust organisms previously reported to survive in oligotrophic cleanroom environments. Presented here are the findings of the first ever comprehensive effort to assess the viability of cells in low-biomass environmental samples, and correlate differential viability with phylogenetic affiliation.
Promoter analysis of the DHCR24 (3β-hydroxysterol Δ24-reductase) gene: characterization of SREBP (sterol-regulatoryelement-binding protein)-mediated activation
Authors: Daimiel Lidia A. , Fernández-Suárez María E. , Rodríguez-Acebes Sara , Crespo Lorena , Lasunción Miguel A. , Gómez-Coronado Diego , Martínez-Botas Javier 
Published: October 2012

DHCR24 (3β-hydroxysterol Δ24-reductase) catalyses the reduction of the C-24 double bond of sterol intermediates during cholesterol biosynthesis. DHCR24 has also been involved in cell growth, senescence and cellular response to oncogenic and oxidative stress. Despite its important roles, little is known about the transcriptional mechanisms controlling DHCR24 gene expression. We analysed the proximal promoter region and the cholesterol-mediated regulation of DHCR24. A putative SRE (sterol-regulatory element) at −98/−90 bp of the transcription start site was identified. Other putative regulatory elements commonly found in SREBP (SRE-binding protein)-targeted genes were also identified. Sterol responsiveness was analysed by luciferase reporter assays of approximately 1 kb 5′-flanking region of the human DHCR24 gene in HepG2 and SK-N-MC cells. EMSAs (electrophoretic mobility-shift assays) and ChIP (chromatin immunoprecipitation) assays demonstrated cholesterol-dependent recruitment and binding of SREBPs to the putative SRE. Given the presence of several CACCC-boxes in the DHCR24 proximal promoter, we assessed the role of KLF5 (Krüppel-like factor 5) in androgen-regulated DHCR24 expression. DHT (dihydrotestosterone) increased DHCR24 expression synergistically with lovastatin. However, DHT was unable to activate the DHCR24 proximal promoter, whereas KLF5 did, indicating that this mechanism is not involved in the androgen-induced stimulation of DHCR24 expression. The results of the present study allow the elucidation of the mechanism of regulation of the DHCR24 gene by cholesterol availability and identification of other putative cis-acting elements which may be relevant for the regulation of DHCR24 expression.
Hot-wire substoichiometric tungsten oxide films deposited in hydrogen environment with n-type conductivity
Authors: Kostis I , Michalas L , Vasilopoulou M , Konofaos N , Papaioannou G , Iliadis A A , Kennou S , Giannakopoulos K , Papadimitropoulos G , Davazoglou D 
Published: October 2012

Abstract
Substoichiometric tungsten oxide nanostructured films were synthesized by a hot-wire deposition technique in hydrogen-rich environment and characterized for their structural and electrical properties. A semiconducting behaviour was identified, allowing n-type conductivity even at room temperature which is an important result since it is well known that fully stoichiometric tungsten trioxide is nearly an insulator. Current–voltage characteristics for various temperatures were measured for tungsten oxide/Si heterostructures and analysed using proper modelling. As a result, the conduction mechanism inside the films was identified and found to be of a dual nature, with variable range hopping being dominant at near room temperatures. The saturation current was found to be thermally activated and the activation energy was calculated at 0.40 eV and the grain boundaries barrier at 150 meV. From Hall measurements it was also revealed that the dominant carriers are electrons and a carrier concentration of about 1014 cm−3 was estimated.
Dielectric breakdown properties of SF6–N2 mixtures in the temperature range 300–3000 K
Authors: Li Xingwen , Zhao Hu , Jia Shenli 
Published: October 2012

Abstract
Reduced critical electric field strength (E/N)cr is an important indicator for the evaluation of dielectric breakdown of SF6 and its mixtures. This paper aims to analytically investigate the dielectric breakdown properties of SF6–N2 mixtures. First, (α − η)/N and (E/N)cr of SF6–N2 mixtures at room temperature, and then (E/N)cr of hot SF6 at several pressures are calculated and compared with other studies. The results confirmed the validity of the present calculation method and parameters. In addition, the electron energy distribution function, reduced ionization coefficient α/N and attachment coefficient η/N of SF6–N2 mixtures are obtained at different proportions and under 1 atm in the gas temperature range 300–3000 K. Then (E/N)cr can be determined when the effective ionization coefficient (α − η)/N = 0. The results show that in a certain temperature range, due to the effect of N2 on reduction in the proportion of high-energy electrons, (E/N)cr of SF6–N2 mixtures will be enhanced by increasing N2.
Controlling surface hydroxylation of nanoporous silica by ion bombardment
Authors: Van Cleve E , Charnvanichborikarn S , Kucheyev S O 
Published: October 2012

Abstract
Due to a large fraction of undercoordinated surface atoms in nanoporous solids, the surface composition could have a profound effect on their properties. Here, we use mass spectrometry to study ion-beam-induced desorption from silica aerogels. Results show that the dominant ion-beam-induced desorption species is the hydrogen molecule. Bombardment with ions of different masses causes dehydroxylation of silica nanoligaments, with the desorption efficiency scaling linearly with the electronic stopping power of ions. These results demonstrate that ion bombardment can be used for controlling surface hydroxylation of nanoporous silica.
Evolution at Two Levels in Fire Ants: The Relationship between Patterns of Gene Expression and Protein Sequence Evolution
Authors: Hunt Brendan G. , Ometto Lino , Keller Laurent , Goodisman Michael A.D. 
Published: October 2012

Abstract
Variation in protein sequence and gene expression each contribute to phenotypic diversity, and may be subject to similar selective pressures. Eusocial insects are particularly useful for investigating the evolutionary link between protein sequence and condition-dependent patterns of gene expression because gene expression plays a central role in determining differences between eusocial insect sexes and castes. We investigated the relationship between protein coding sequence evolution and gene expression patterns in the fire ants Solenopsis invicta, S. richteri, and their hybrids to gain greater insight into how selection jointly operates on gene expression and coding sequence. We found that genes with high expression variability within castes and sexes were frequently differentially expressed between castes and sexes, as well as between species and hybrids. These results indicate that genes showing high variation in expression in one context also tend to show high variation in expression in other contexts. Our analyses further revealed that variation in both intra- and interspecific gene expression was positively associated with rate of protein sequence evolution in Solenopsis. This suggests that selective constraints on a gene operate both at the level of protein sequence and at the level of gene expression regulation. Overall, our study provides one of the strongest demonstrations that selective constraints mediate both protein sequence evolution and gene expression variability across different biological contexts and timescales.
Molecular mechanisms of LKB1 induced cell cycle arrest
Authors: Zhong Dian‐sheng , Sun Lin‐lin , Dong Li‐xia 
Published: October 2012

AbstractLKB1 is a serine/threonine protein kinase mutated in patients with Peutz‐Jeghers syndrome. Biallelic inactivation of LKB1 is present in up to 30% of cases of non‐small cell lung cancer (NSCLC). As a tumor suppressor, LKB1 functions in arresting the cell cycle and inhibiting cell growth. LKB1 leads to induction of p21/WAF1 expression in a p53‐dependent mechanism, which is mediated by cytoplasmic LKB1 initiating negative regulation of cell growth or nuclear LKB1 directly involved in transcriptional regulation of p21/WAF1. Alternatively, p53 and p21/WAF1‐independent mechanism of regulating cell cycle by LKB1 is also reported.
Aquaporin‐4 Deficiency Attenuates Opioid Dependence through Suppressing Glutamate Transporter‐1 Down‐regulation and Maintaining Glutamate Homeostasis
Authors: Yan Hai‐Tao , Wu Ning , Lu Xin‐Qiang , Su Rui‐Bin , Zheng Jian‐Quan , Li Jin 
Published: October 2012

SummaryBackgroundGlutamate homeostasis plays a critical role in mediating the addiction‐related behaviors. Therefore, preventing the disruption or reestablishing of it is a novel strategy for the treatment of addiction. Glutamate transporters are responsible for clearing extracellular glutamate and maintaining glutamate homeostasis. Our previous work demonstrated that aquaporin‐4 (AQP4) deficiency attenuated morphine dependence, but the mechanisms are unclear. According to the recent evidence that AQP4 might form a functional complex with glutamate transporter‐1 (GLT‐1), this study focused on whether AQP4 participates in the modulation of GLT‐1 and glutamate homeostasis in morphine‐dependent mice.ResultsWe found that AQP4 knockout prevented the down‐regulations of GLT‐1 expression and glutamate clearance when mice were repeatedly treated with morphine. Further study revealed that inhibition of GLT‐1 by dihydrokainic acid (DHK) initiated morphine dependence in AQP4 knockout mice. In addition, AQP4 knockout abolished both decreases and increases in the extracellular glutamate levels in the prefrontal cortex during repeated morphine treatment and naloxone‐precipitated withdrawal.ConclusionAQP4 deficiency suppresses the down‐regulation of GLT‐1, and the disruption of glutamate homeostasis caused by repeated exposure to morphine, pointing to a strategy for maintaining glutamate homeostasis and thereby treating addiction through the modulation of AQP4 function and expression.
Plant defense against fall armyworm in micro‐sympatric maize (Zea mays ssp. mays) and Balsas teosinte (Zea mays ssp. parviglumis)
Authors: Takahashi Chelsea G. , Kalns Lauren L. , Bernal Julio S. 
Published: October 2012

AbstractMaize [Zea mays L. ssp. mays (Poaceae)] was domesticated from Balsas teosinte (Zea mays ssp. parviglumis Iltis & Doebley) in present‐day Mexico. Fall armyworm, Spodoptera frugiperda JE Smith (Lepidoptera: Noctuidae), is among the most important pests of maize in Mexico and Central America. We compared the strength of plant defenses against fall armyworm between micro‐sympatric landrace maize and Balsas teosinte in the field and laboratory. The field comparison, conducted in Mexico, consisted of comparing the frequency of fall armyworm infestation between young maize and Balsas teosinte plants in dryland agricultural fields in which Balsas teosinte grew as a weed. The laboratory comparison contrasted the performance of fall armyworm larvae provided a diet of leaf tissue excised from maize or Balsas teosinte plants that were intact or had been primed by larval feeding. In the field, maize plants were more frequently infested with fall armyworm than Balsas teosinte plants: over 3 years and three fields, maize was infested at a ca. 1.8‐fold greater rate than Balsas teosinte. In the laboratory, larval growth, but not survivorship, was differently affected by feeding on maize vs. Balsas teosinte, and on primed vs. intact plants. Specifically, survivorship was ca. 98%, and did not differ between maize and Balsas teosinte, nor between primed and intact plants. Larvae grew less on intact vs. primed maize, and similarly on intact vs. primed Balsas teosinte; overall, growth was 1.2‐fold greater on maize compared to Balsas teosinte, and on primed compared to intact plants. Parallel observations showed that the differences in growth could not be attributed to the amount of leaf tissue consumed by larvae. We discuss our results in relation to differences in the strength of plant defenses between crops and their ancestors, the relevance of unmanaged Balsas teosinte introgression in the context of fall armyworm defenses in maize, and whether greater growth of larvae on primed vs. intact plants signifies herbivore offense.
Differential effects of blockade of ERG channels on gamma oscillations and excitability in rat hippocampal slices
Authors: Fano Silvia , Çalışkan Gürsel , Heinemann Uwe 
Published: October 2012

AbstractAgents such as sertindole and astemizole affect heart action by inducing long‐QT syndrome, suggesting that apart from their neuronal actions through histamine receptors, 5‐HT2 serotonin receptors and D2 dopamine receptors they also affect ether‐a‐go‐go channels and particularly ether‐a‐go‐go‐related (ERG) potassium (K+) channels, comprising the Kv11.1, Kv11.2 and Kv11.3 voltage‐gated potassium currents. Changes in ERG K+ channel expression and activity have been reported and may be linked to schizophrenia [Huffaker, S.J., Chen, J., Nicodemus, K.K., Sambataro, F., Yang, F., Mattay, V., Lipska, B.K., Hyde, T.M., Song, J., Rujescu, D., Giegling, I., Mayilyan, K., Proust, M.J., Soghoyan, A., Caforio, G., Callicott, J.H., Bertolino, A., Meyer‐Lindenberg, A., Chang, J., Ji, Y., Egan, M.F., Goldberg, T.E., Kleinman, J.E., Lu, B. & Weinberger DR. (2009). Nat. Med., 15, 509–518; Shepard, P.D., Canavier, C.C. & Levitan, E.S. (2007). Schizophr Bull., 33, 1263–1269]. We have previously shown that histamine H1 blockers augment gamma oscillations (γ) which are thought to be involved in cognition and storage of information. These effects were particularly pronounced for γ induced by acetylcholine. Here we have compared neuronal effects of three agents which interfere with ERG K+ channels. We found that astemizole and sertindole, but not the Kv11 channel blocker E4031, augmented γ induced by acetylcholine in hippocampal slices. Kainate‐induced γ were only affected by astemizole. Evoked responses induced by stratum radiatum stimulation in area CA1 revealed that only E4031 augmented stimulus‐induced synaptic potentials and neuronal excitability. Our findings suggest that Kv11 channels are involved in neuronal excitability without clear effects on γ and that the effect of astemizole is related to actions on H1 receptors.
Compensatory dynamics and the stability of phytoplankton biomass during four decades of eutrophication and oligotrophication
Authors: Jochimsen Marc C. , Kümmerlin Reiner , Straile Dietmar 
Published: October 2012

AbstractThe link between compensatory dynamics and regime shifts is not well understood. We analyse a regime shift in phytoplankton in a large lake with respect to: (1) environmental forcing and (2) the type of dynamics (compensatory or synchronous) between phytoplankton groups. The regime shift in phytoplankton was related to gradual changes in nutrient levels, but unrelated to an almost concurrent shift in climatic conditions. The relationship between total phytoplankton biomass and phosphorus concentrations was sigmoid. Trajectories of phytoplankton biomass and community dynamics suggest that eutrophication effects can successfully be reversed when management efforts decrease nutrient loading to a level sufficiently low to overcome community resilience. The regime shift was associated with a loss of biomass compensation and compensatory dynamics among the phytoplankton groups. This suggests that the type of interactions is important for a better understanding of the existence and shape of nonlinear responses of phytoplankton biomass to environmental change.
Effects of disturbance on an urban river food web
Authors: CALIZZA EDOARDO , COSTANTINI MARIA LETIZIA , ROSSI DAVID , CARLINO PASQUALE , ROSSI LORETO 
Published: October 2012

Summary1. Natural and anthropogenic disturbances are influential factors in river ecosystems. Lowland rivers that cross urbanised areas experience direct disturbance due to urbanisation, affecting suitability for many vertebrate and invertebrate species and with important implications for ecosystem functioning and stability. In addition, lowland rivers are potentially subjected to major flood events, whose effects may be exacerbated by urbanisation in the river basin. A greater understanding of the combined effects of flood disturbance and urbanisation is needed if we are to preserve riverine ecosystems and improve management strategies.2. We characterised macroinvertebrate, detritus‐based food webs upstream and downstream of Rome (Italy) before a period of exceptional flooding and at intervals until 71 days following the final flood event. We studied community and food‐web characteristics, combining carbon and nitrogen stable isotope analysis with macroinvertebrate population census data.3. The flood altered the species assemblage at both upstream and downstream locations. The food webs shifted towards a more complex configuration, with increased trophic generalism, linkage density and mean chain length. However, the food web at the upstream location gradually recovered its pre‐flood configuration, whereas at the downstream location, where flood effects were stronger, the food web showed little capacity for recovery within the time span of the study. The contrasting food‐web responses can be explained with reference to differences in resource availability for detritivores and predators and in water turbidity, which in turn reflect an interaction between flood disturbance and river basin urbanisation.4. The description of short‐term variations in food‐web properties may help to improve ecosystem monitoring and the management of freshwater bodies and can be used to assess short‐term and long‐term effects of disturbance. A better understanding of the negative effects of urban pressure on macroinvertebrate community stability should help to define appropriate measures for the conservation and restoration of urbanised river areas, especially given that extreme flood events are expected to increase due to climatic change.
The implementation of a tobacco dependence education curriculum in a Swiss Dental Hygiene School – an 8‐year review
Authors: Ramseier CA , Burri M , Berres F , Davis JM 
Published: October 2012

AbstractObjectiveThe aim of our investigation was to review the implementation of a comprehensive tobacco dependence education (TDE) curriculum at the Medi School of Dental Hygiene (MSDH), Bern, Switzerland, 2001–2008.MethodsIn 2001, new forms to record patients' tobacco use history and willingness to quit were created for all the MSDH patients. In 2002, a new theoretically based tobacco dependence treatment protocol was implemented into the MSDH curriculum. Students received instruction on how to provide brief tobacco use dependence interventions as well as maintain detailed records of patient tobacco use and cessation interventions for every smoker at all dental hygiene visits.ResultsIn 2002, 17 lecture hours were added to the following subjects: pathology, periodontology, preventive dentistry, pharmacology and psychology. During the same time period, 2213 patients (56.9% women) have visited the MSDH. Smoking status was recorded in 85.7% of all the patients (30.2% smokers). Brief tobacco use interventions were recorded in 36.8% of all smokers while 7.6% of these have reported to quit smoking.ConclusionsOverall, the new TDE curriculum was successfully implemented and accepted by the MSDH faculty. Applications in the clinical practice, however, may still be improved to better identify smokers and increase initial and follow‐up interventions potentially leading to higher quit rates.
The evolution of floral mimicry: identifying traits that visually attract pollinators
Authors: Jersáková Jana , Jürgens Andreas , Šmilauer Petr , Johnson Steven D. 
Published: October 2012

Summary

Some orchids have been proposed to be Batesian floral mimics imitating flowers of sympatric rewarding species to attract pollinators. It is not yet well understood which traits are critical for pollinator attraction, although colour, shape and scent have all been implicated.

We conducted field‐based behavioural experiments using pairwise combinations of plastic flowers differing in spectral and shape properties offered to long‐proboscid tabanid flies (Philoliche aethiopica) at two sites – one where the fly‐pollinated orchid mimic Disa pulchra occurs with its pink‐flowered model, the iris Watsonia lepida and another where the flies forage on a blue‐flowered rewarding plant Agapanthus campanulatus.

Flies intensively visited and probed plastic flowers of colours indistinguishable in a fly vision model from those of the rewarding plants. Inflorescence architecture and brightness of plastic flowers made little difference to fly attraction, but those that matched the shape and nectar guides of Watsonia flowers were significantly more attractive.

Flowers of the three focal plant species are weakly scented and divergent in scent chemistry.

This study shows that traits that mimic, in order of importance, the spectra, shape and nectar guide patterns of flowers of rewarding plants would be under strong selection in food‐deceptive orchids as they maximize attractiveness to their pollinators. Our experiments also help to explain why deceptive orchids in general often seem to match the flowers of sympatric rewarding plants more in visual attributes than in scent chemistry.
Increased resolution in neutral atom microscopy
Authors: WITHAM P. J. , SÁNCHEZ E. J. 
Published: October 2012

SummaryThe neutral atom microscope uses a beam of thermal noncharged atoms or molecules to probe an atomic surface with very low interaction energies (<70 meV). Continued optimization of the ‘pinhole’ neutral atom microscope has improved resolution to 0.35 μm. Recent images are presented demonstrating resolution and the contrast mechanisms identified so far. The future potential for sub‐100 nm resolution is discussed.