bluuebunny/crossref_metadata_2025_split huggingface dataset:
HPrK Regulates Succinate-Mediated Catabolite Repression in the Gram-Negative SymbiontSinorhizobium meliloti
Authors: Pinedo Catalina Arango , Gage Daniel J. 
Published: October 2008

ABSTRACTThe HPrK kinase/phosphatase is a common component of the phosphotransferase system (PTS) of gram-positive bacteria and regulates catabolite repression through phosphorylation/dephosphorylation of its substrate, the PTS protein HPr, at a conserved serine residue. Phosphorylation of HPr by HPrK also affects additional phosphorylation of HPr by the PTS enzyme EI at a conserved histidine residue.Sinorhizobium melilotican live as symbionts inside legume root nodules or as free-living organisms and is one of the relatively rare gram-negative bacteria known to have a gene encoding HPrK. We have constructedS. melilotimutants that lack HPrK or that lack key amino acids in HPr that are likely phosphorylated by HPrK and EI. Deletion ofhprKinS. melilotienhanced catabolite repression caused by succinate, as did an S53A substitution in HPr. Introduction of an H22A substitution into HPr alleviated the strong catabolite repression phenotypes of strains carrying ΔhprKorhpr(S53A) mutations, demonstrating that HPr-His22-P is needed for strong catabolite repression. Furthermore, strains with ahpr(H22A) allele exhibited relaxed catabolite repression. These results suggest that HPrK phosphorylates HPr at the serine-53 residue, that HPr-Ser53-P inhibits phosphorylation at the histidine-22 residue, and that HPr-His22-P enhances catabolite repression in the presence of succinate. Additional experiments show that ΔhprKmutants overproduce exopolysaccharides and form nodules that do not fix nitrogen.
A Unique GTP-Dependent Sporulation Sensor Histidine Kinase in
Bacillus anthracis
Authors: Scaramozzino Francesca , White Andrea , Perego Marta , Hoch James A. 
Published: October 2008

ABSTRACT

The
Bacillus anthracis
BA2291 gene codes for a sensor histidine kinase involved in the induction of sporulation. Genes for orthologs of the sensor domain of the BA2291 kinase exist in virulence plasmids in this organism, and these proteins, when expressed, inhibit sporulation by converting BA2291 to an apparent phosphatase of the sporulation phosphorelay. Evidence suggests that the sensor domains inhibit BA2291 by titrating its activating signal ligand. Studies with purified BA2291 revealed that this kinase is uniquely specific for GTP in the forward reaction and GDP in the reverse reaction. The G1 motif of BA2291 is highly modified from ATP-specific histidine kinases, and modeling this motif in the structure of the kinase catalytic domain suggested how guanine binds to the region. A mutation in the putative coiled-coil linker between the sensor domain and the catalytic domains was found to decrease the rate of the forward autophosphorylation reaction and not affect the reverse reaction from phosphorylated Spo0F. The results suggest that the activating ligand for BA2291 is a critical signal for sporulation and in a limited concentration in the cell. Decreasing the response to it either by slowing the forward reaction through mutation or by titration of the ligand by expressing the plasmid-encoded sensor domains switches BA2291 from an inducer to an inhibitor of the phosphorelay and sporulation.
The Genome of
Burkholderia cenocepacia
J2315, an Epidemic Pathogen of Cystic Fibrosis Patients
Authors: Holden Matthew T. G. , Seth-Smith Helena M. B. , Crossman Lisa C. , Sebaihia Mohammed , Bentley Stephen D. , Cerdeño-Tárraga Ana M. , Thomson Nicholas R. , Bason Nathalie , Quail Michael A. , Sharp Sarah , Cherevach Inna , Churcher Carol , Goodhead Ian , Hauser Heidi , Holroyd Nancy , Mungall Karen , Scott Paul , Walker Danielle , White Brian , Rose Helen , Iversen Pernille , Mil-Homens Dalila , Rocha Eduardo P. C. , Fialho Arsenio M. , Baldwin Adam , Dowson Christopher , Barrell Bart G. , Govan John R. , Vandamme Peter , Hart C. Anthony , Mahenthiralingam Eshwar , Parkhill Julian 
Published: October 2008

ABSTRACT

Bacterial infections of the lungs of cystic fibrosis (CF) patients cause major complications in the treatment of this common genetic disease.
Burkholderia cenocepacia
infection is particularly problematic since this organism has high levels of antibiotic resistance, making it difficult to eradicate; the resulting chronic infections are associated with severe declines in lung function and increased mortality rates.
B. cenocepacia
strain J2315 was isolated from a CF patient and is a member of the epidemic ET12 lineage that originated in Canada or the United Kingdom and spread to Europe. The 8.06-Mb genome of this highly transmissible pathogen comprises three circular chromosomes and a plasmid and encodes a broad array of functions typical of this metabolically versatile genus, as well as numerous virulence and drug resistance functions. Although
B. cenocepacia
strains can be isolated from soil and can be pathogenic to both plants and man, J2315 is representative of a lineage of
B. cenocepacia
rarely isolated from the environment and which spreads between CF patients. Comparative analysis revealed that ca. 21% of the genome is unique in comparison to other strains of
B. cenocepacia
, highlighting the genomic plasticity of this species. Pseudogenes in virulence determinants suggest that the pathogenic response of J2315 may have been recently selected to promote persistence in the CF lung. The J2315 genome contains evidence that its unique and highly adapted genetic content has played a significant role in its success as an epidemic CF pathogen.
Dissecting the Role of the N-Terminal Region of the
Escherichia coli
Global Transcription Factor FNR
Authors: Yan Aixin , Kiley Patricia J. 
Published: October 2008

ABSTRACT

The role of the N-terminal region of the transcription factor FNR, which immediately precedes the first ligand (Cys20) of the [4Fe-4S] cluster, was investigated. We found that truncation mutants that removed residues 2 to 16 and 2 to 17 had wild-type levels of FNR protein but surprisingly altered O
2
regulation.
SPONSORSHIP, COMMUNITY, AND SOCIAL CAPITAL RESOURCES IN INDIGENOUS COMMUNITIES
Authors: SWINNEY JANE 
Published: October 2008

This exploratory study conducted in heavily indigenous communities was undertaken to investigate entrepreneurial perceptions of community (sense of place, image, and positioning) and social capital (reciprocity, shared vision, and density of networks) resources present in rural communities, and the sponsorship involvement of the entrepreneurs in community activities. The uniqueness of the study was its focus on indigenous communities with a higher than state average Native-American population. Previous work highlighting the collective nature and attitudes of Native Americans was not supported for the entrepreneurs in this study. Indigenous entrepreneurs were those who identified their ethnicity as Native American and majority entrepreneurs were those who identified their ethnicity as white. For indigenous entrepreneurs, there were no significant correlations among social capital resources or community resources and sponsorship. For majority entrepreneurs, all three social capital resources correlated significantly with sponsorship, and none of the community resources correlated significantly with sponsorship. The correlation between image and sponsorship was statistically significant for the total sample (n = 149).Mean scores to each of the social capital and community resources were calculated. Positioning was the resource with the lowest mean score. The positioning statement differentiates one downtown from a competing downtown and is indicative of how the downtown wants to be perceived. The findings point to the need for economic development officials to strengthen community positioning through an improved understanding and acceptance of the community's position statement by business owners in the community.
A Dual Mass Flux Framework for Boundary Layer Convection. Part I: Transport
Authors: Neggers Roel A. J. , Köhler Martin , Beljaars Anton C. M. 
Published: October 2008

Abstract
This study considers the question of what is the least complex bulk mass flux framework that can still conceptually reproduce the smoothly varying coupling between the shallow convective cloud layer and the subcloud mixed layer. To this end, the model complexity of the classic single bulk mass flux scheme is enhanced. Inspired by recent large-eddy simulation results, the authors argue that two relatively minor but key conceptual modifications are already sufficient to achieve this goal: (i) retaining a dry transporting updraft in the moist limit and (ii) applying continuous updraft area partitioning to this dual mass flux (DualM) framework. The dry updraft represents all internal mixed layer updrafts that terminate near the mixed layer top, whereas the moist updraft represents all updrafts that condense and rise out of the mixed layer as buoyant cumulus clouds. The continuous area partitioning between the dry and moist updraft is a function of moist convective inhibition above the mixed layer top. Updraft initialization is a function of the updraft area fraction and is therefore consistent with the updraft definition. It is argued that the model complexity thus enhanced is sufficient to allow reproduction of various phenomena involved in the cloud–subcloud coupling, namely (i) dry countergradient transport within the mixed layer that is independent of the moist updraft, (ii) soft triggering of moist convective flux throughout the boundary layer, and (iii) a smooth response to smoothly varying forcings, including the reproduction of gradual transitions to and from shallow cumulus convection.
The DualM framework is evaluated by implementing in the Eddy Diffusivity Mass Flux (EDMF) boundary layer scheme of the ECMWF’s Integrated Forecasting System. Single column model experiments are evaluated against large-eddy simulation results for a range of different cases that span a broad parameter space of cloud–subcloud coupling intensities. The results illustrate that also in numerical practice the DualM framework can reproduce gradual transitions to and from shallow cumulus convection. Model behavior is further explored through experiments in which model complexity is purposely reduced, thus mimicking a single bulk updraft setup. This gives more insight into the new model-internal interactions and explains the obtained case results.
A Dual Mass Flux Framework for Boundary Layer Convection. Part II: Clouds
Authors: Neggers Roel A. J. 
Published: October 2008

Abstract
This paper presents the extension of the eddy diffusivity mass flux (EDMF) framework for turbulent transport into the statistical modeling of boundary layer clouds. The advection–diffusion decomposition that defines EDMF is projected onto the turbulent distribution as used in the statistical cloud model. Each EDMF component is thus assigned its own independent probability density function (PDF), resulting in an updraft PDF and a diffusive PDF. This double PDF system is configured and integrated in conserved variable space, with the position and orientation of each PDF determined by its unique nature. The parameterization of the associated updraft/diffusion decomposition of variance introduces close ties to the transport scheme; whereas the grid box mean variance is reconstructed using a prognostic variance budget, the variance of the updraft component is parameterized as a function of the spread among various resolved model updrafts. Individual model components and the scheme as a whole are evaluated in detail against large-eddy simulations of a number of prototype subtropical trade wind cases. The results show that various structures in cloud fraction, condensate, and variance are reproduced. The diffusive PDF acts to represent stratiform clouds; the advective PDF represents cumuliform clouds in conditionally unstable layers. This allows representation of complex scenarios in which both cloud forms occur, such as the transitional trade wind regime featuring cumulus rising into stratocumulus.
Error Structure and Atmospheric Temperature Trends in Observations from the Microwave Sounding Unit
Authors: Zou Cheng-Zhi , Gao Mei , Goldberg Mitchell D. 
Published: October 2008

Abstract
The Microwave Sounding Unit (MSU) onboard the National Oceanic and Atmospheric Administration polar-orbiting satellites measures the atmospheric temperature from the surface to the lower stratosphere under all weather conditions, excluding precipitation. Although designed primarily for monitoring weather processes, the MSU observations have been extensively used for detecting climate trends, and calibration errors are a major source of uncertainty. To reduce this uncertainty, an intercalibration method based on the simultaneous nadir overpass (SNO) matchups for the MSU instruments on satellites NOAA-10, -11, -12, and -14 was developed. Due to orbital geometry, the SNO matchups are confined to the polar regions, where the brightness temperature range is slightly smaller than the global range. Nevertheless, the resulting calibration coefficients are applied globally to the entire life cycle of an MSU satellite.
Such intercalibration reduces intersatellite biases by an order of magnitude compared to prelaunch calibration and, thus, results in well-merged time series for the MSU channels 2, 3, and 4, which respectively represent the deep layer temperature of the midtroposphere (T2), tropopause (T3), and lower stratosphere (T4). Focusing on the global atmosphere over ocean surfaces, trends for the SNO-calibrated T2, T3, and T4 are, respectively, 0.21 ± 0.07, 0.08 ± 0.08, and −0.38 ± 0.27 K decade−1 from 1987 to 2006. These trends are independent of the number of limb-corrected footprints used in the dataset, and trend differences are marginal for varying bias correction techniques for merging the overlapping satellites on top of the SNO calibration.
The spatial pattern of the trends reveals the tropical midtroposphere to have warmed at a rate of 0.28 ± 0.19 K decade−1, while the Arctic atmosphere warmed 2 to 3 times faster than the global average. The troposphere and lower stratosphere, however, cooled across the southern Indian and Atlantic Oceans adjacent to the Antarctic continent. To remove the stratospheric cooling effect in T2, channel trends from T2 and T3 (T23) and T2 and T4 (T24) were combined. The trend patterns for T23 and T24 are in close agreement, suggesting internal consistencies for the trend patterns of the three channels.
Forced and Internal Twentieth-Century SST Trends in the North Atlantic*
Authors: Ting Mingfang , Kushnir Yochanan , Seager Richard , Li Cuihua 
Published: October 2008

Abstract
In recent years, two alarming trends in North Atlantic climate have been noted: an increase in the intensity and frequency of Atlantic hurricanes and a rapid decrease in Greenland ice sheet volume. Both of these phenomena occurred while a significant warming took place in North Atlantic sea surface temperatures (SSTs), thus sparking a debate on whether the warming is a consequence of natural climate variations, anthropogenic forcing, or both; and if both, what their relative roles are. Here models and observations are used to detect and attribute long-term (multidecadal) twentieth-century North Atlantic (NA) SST changes to their anthropogenic and natural causes. A suite of Intergovernmental Panel on Climate Change (IPCC) twentieth-century (C20C) coupled model simulations with multiple ensemble members and a signal-to-noise maximizing empirical orthogonal function analysis are used to identify a model-based estimate of the forced, anthropogenic component in NA SST variability. Comparing the results to observations, it is argued that the long-term, observed, North Atlantic basin-averaged SSTs combine a forced global warming trend with a distinct, local multidecadal “oscillation” that is outside of the range of the model-simulated, forced component and most likely arose from internal variability. This internal variability produced a cold interval between 1900 and 1930, followed by 30 yr of relative warmth and another cold phase from 1960 to 1990, and a warming since then. This natural variation, referred to previously as the Atlantic Multidecadal Oscillation (AMO), thus played a significant role in the twentieth-century NA SST variability and should be considered in future, near-term climate projections as a mechanism that, depending on its behavior, can act either constructively or destructively with the region’s response to anthropogenic influence, temporarily amplifying or mitigating regional climate change.
Mutual Action Between MMCS Structure and Projectile After Ballistic Impact
Authors: Karamiş M. Baki , Cerit A. Alper , Nair Fehmi 
Published: October 2008

The interaction between a projectile and metal—matrix composites (MMCs) was investigated in terms of macro cracking, petalling and particularly grain deformation of a matrix alloy at the hole section caused by the projectile at high velocity impact. Metal matrix composites were manufactured by squeeze casting using Al alloys reinforced with Al 2O3 or SiC. Additionally, laminated composites with SiC particles and back side supported by Kevlar 49® were manufactured and their ballistic behavior tested. The composite and unreinforced Al alloy targets were subjected to ballistic impact with an armor piercing projectile of 7.62mm caliber at a speed in the range of 770—800 m/s. The macro examination focused on cracking and petalling after impact. The investigation of grain deformations of matrix alloy was conducted by light microscopy in the hole section created by the projectile. The hole section created by the projectile had different profiles. Around the hole sections, different grain deformation rates in different directions took place for reinforced and unreinforced Al alloys. Strong friction took place between the projectile and hole surface and the velocity of the projectile was decreased suddenly in the hole as it met the reinforcement particles in the composite body. These led to deformations of the projectile surface and grain surrounding the reinforcement. In the case of laminate composites, the laminates were fractured and deformed in the direction of projectile movement.
Vasopressin and angiotensin receptors of the medial septal area in the control of mean arterial pressure induced by vasopressin
Authors: Pavan de Arruda Camargo Gabriela Maria , Abrão Saad Wilson , de Arruda Camargo Luiz Antônio 
Published: October 2008

Introduction. Brain arginine8-vasopressin (AVP), through the V1a- and V2-receptors, is essential for the maintenance of mean arterial pressure (MAP). Central AVP interacts with the components of the renin-angiotensin system, which participate in MAP regulation. This study aimed to determine the effects of V1a-, V2- and V1a/V2-AVP selective antagonists and AT1- and AT2-angiotensin II (Ang II) selective antagonists on the MAP induced by AVP injected into the medial septal area (MSA) of the brain.Materials and methods. Male Holtzman rats with stainless steel cannulae implanted into the MSA were used in experiments. Direct MAP was recorded in conscious rats.Results. AVP administration into the MSA caused a prompt and potent pressor response in a dose-dependent fashion. Pretreatment with the V1a- and V2-antagonists reduced, whereas prior injection of the V1a/V2-antagonist induced a decrease in the MAP that remained below the baseline. Both AT1- and AT2-antagonists elicited a decrease, while simultaneous injections of two antagonists were more effective in decreasing the MAP induced by AVP.Conclusion. These results indicate there is a synergism between the V1a- and V2-AVP and AT1and AT2-Ang II receptors in the MSA in the regulation of MAP.
Inhibition of the renin-angiotensin system: effects on tachycardia-induced early electrical remodelling in rabbit atrium
Authors: Laszlo Roman , Eick Christian , Rueb Norman , Weretka Slawomir , Weig Hans-Joerg , Schreieck Juergen , Bosch Ralph F 
Published: October 2008

Introduction. Tachycardia-induced atrial remodelling (as an equivalent to atrial fibrillation) can be influenced by the renin-angiotensin system. Effects of a seven-day enalapril pre-treatment (EPT, 0.16 mg/kg body weight subcutaneously every 24 h) on ionic currents underlying tachycardia-induced early electrical remodelling after 24 h rapid atrial pacing (RAP, 600 beats/min) in rabbit atrium were studied. Materials and methods. Animals were divided into four groups (n=4 each): control; paced only; enalapril only; and enalapril and paced, respectively. Using patch-clamp technique in whole-cell mode, current densities were measured in isolated atrial myocytes. Results. EPT nearly doubled L-type calcium current (ICa,L, −7.7±0.6 pA/pF [control] vs. f −12.3±1.2 pA/pF [enalapril only]). RAP reduced ICa,L to −3.6±0.7 pA/pF (paced only). Also after EPT, RAP led to a significant downregulation of ICa,L by 39% (−7.5±1.3 pA/pF [paced and enalapril]). RAP decreased transient outward potassium current (Ito, −45%, 51.5±3.9 pA/pF [control] vs. 28.5±4.5 pA/pF [paced only]). EPT did not alter Ito (44.2±8.1 pA/pF [enalapril only]). However, RAP did not affect Ito in enalapril-treated animals and averaged 50.4±9.8 pA/pF (paced and enalapril). Conclusions. In summary, EPT has several effects on ion channels in rabbit atrium: 1) EPT increases ICa,L current density, but cannot prevent its downregulation due to RAP; 2) EPT has no influence on Ito current density, but can prevent its downregulation due to RAP. Although changes of single ion channels must be interpreted in context of the complex atrial electrophysiology as a whole, our results provide a possible explanation of the in vivo observation that angiotensin-converting enzyme inhibition is mainly beneficial on the early electrical remodelling due to the atrial fibrillation-equivalent RAP.
Surveillance for Creutzfeldt-Jakob disease in China from 2006 to 2007
Authors: Shi Qi , Gao Chen , Zhou Wei , Zhang Bao-Yun , Chen Jian-Ming , Tian Chan , Jiang Hui-Ying , Han Jun , Xiang Ni-Juan , Wang Xiao-Fang , Gao Yong-Jun , Dong Xiao-Ping 
Published: October 2008

Abstract

Background
Human transmissible spongiform encephalopathies (HTSE), or Creutzfeldt-Jakob disease (CJD), is a group of rare and fatal diseases in central nervous system. Since outbreak of bovine spongiform encephalopathy (BSE) and variant CJD, a worldwide CJD surveillance network has been established under the proposition of WHO. In China, a national CJD surveillance system has started since 2002. The data of CJD surveillance from 2006 to 2007 was analyzed.

Methods
Total 12 provinces are included in CJD surveillance system. The surveillance unit in each province consists of one or two sentinel hospitals and the provincial CDC. All suspected CJD cases reported from CJD surveillance were diagnosed and subtyped based on the diagnostic criteria for CJD issued by WHO.

Results
Total 192 suspected CJD cases were reported and 5 genetic CJD, 51 probable and 30 possible sporadic CJD (sCJD) cases were diagnosed. The collected sCJD cases distribute sporadically without geographical clustering and seasonal relativity and the highest incidences in both probable and possible sCJD cases appeared in the group of 60–69 year. The most common three foremost symptoms were progressive dementia, cerebellum and mental-related symptoms. The probable sCJD patients owning both typical EEG alteration and CSF protein 14-3-3 positive have more characteristic clinical syndromes than the ones having only one positive. The polymorphisms of codon 129 of all tested reported cases shows typical patterns of Han Chinese as previous reports, that M129M are predominant whereas M129V are seldom.

Conclusion
Chinese CJD patients possessed similar epidemiological and clinical characteristics as worldwide.