bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ternary complex formation between AmtB, GlnZ and the nitrogenase regulatory enzyme DraG reveals a novel facet of nitrogen regulation in bacteria
Authors: Huergo Luciano F. , Merrick Mike , Pedrosa Fábio O. , Chubatsu Leda S. , Araujo Luíza M. , Souza Emanuel M. 
Published: November 2007

SummaryAmmonium movement across biological membranes is facilitated by a class of ubiquitous channel proteins from the Amt/Rh family. Amt proteins have also been implicated in cellular responses to ammonium availability in many organisms. Ammonium sensing by Amt in bacteria is mediated by complex formation with cytosolic proteins of the PII family. In this study we have characterized in vitro complex formation between the AmtB and PII proteins (GlnB and GlnZ) from the diazotrophic plant‐associative bacterium Azospirillum brasilense. AmtB–PII complex formation only occurred in the presence of adenine nucleotides and was sensitive to 2‐oxoglutarate when Mg2+ and ATP were present, but not when ATP was substituted by ADP. We have also shown in vitro complex formation between GlnZ and the nitrogenase regulatory enzyme DraG, which was stimulated by ADP. The stoichiometry of this complex was 1:1 (DraG monomer : GlnZ trimer). We have previously reported that in vivo high levels of extracellular ammonium cause DraG to be sequestered to the cell membrane in an AmtB and GlnZ‐dependent manner. We now report the reconstitution of a ternary complex involving AmtB, GlnZ and DraG in vitro. Sequestration of a regulatory protein by the membrane‐bound AmtB–PII complex defines a new regulatory role for Amt proteins in Prokaryotes.
Regulation of nitrate reductase by nitric oxide in Chinese cabbage pakchoi (Brassica chinensis L.)
Authors: DU SHAOTING , ZHANG YONGSONG , LIN XIANYONG , WANG YUE , TANG CAIXIAN 
Published: November 2007

ABSTRACTNitrate reductase (NR), a committed enzyme in nitrate assimilation, involves generation of nitric oxide (NO) in plants. Here we show that the NR activity was significantly enhanced by the addition of NO donors sodium nitroprusside (SNP) and NONOate (diethylamine NONOate sodium) to the culturing solution, whereas it was decreased by NO scavenger 2‐(4‐carboxyphenyl)‐4,4,5,5‐tetramethyl‐imidazoline‐1‐oxyl‐3‐oxide (cPTIO). Interestingly, both NO gas and SNP directly enhanced but cPTIO inhibited the NR activities of crude enzyme extracts and purified NR enzyme. The cPTIO terminated the interaction between NR‐generated NO and the NR itself. Furthermore, the NR protein content was not affected by the SNP treatment. The investigation of the partial reactions catalysed by purified NR using various electron donors and acceptors indicated that the haem and molybdenum centres in NR were the two sites activated by NO. The results suggest that the activation of NR activity by NO is regulated at the post‐translational level, probably via a direct interaction mechanism. Accordingly, the concentration of nitrate both in leaves and roots was decreased after 2 weeks of cultivation with SNP. The present study identifies a new mechanism of NR regulation and nitrate assimilation, which provides important new insights into the complex regulation of N‐metabolism in plants.
Survival of Tilletia indica teliospores under European soil conditions
Authors: Inman A. , Magnus H. A. , Riccioni L. , Hughes K. , Coates M. , Barnes A. , Barton V. , Sansford C. , Valvassori M. , Di Giambattista G. , Porta‐Puglia A. , Razzaghian J. , Peterson G. 
Published: November 2007

As part of developing a European Pest Risk Analysis (PRA) for Tilletia indica, the causal agent of Karnal bunt of wheat, teliospore survival studies were done outside under quarantine containment at three European sites (Norway, UK, Italy). At each site, experiments were set up in three consecutive years (Experiments 1, 2 & 3) to determine teliospore survival over time (1–3 years) at 5, 10 and 20 cm depths. Experiments were sampled annually and survival assessed in relation to teliospore recovery and to germination at recovery (T0) and 3 months after recovery in case of burial‐induced dormancy (T3). Teliospores survived at all three sites at all depths over all the time periods studied. At each site, there was no evidence of a marked decline in teliospore recovery between sampling years, except in one set of years in one Norwegian experiment. There was no consistent effect of depth on recovery. In general there was little evidence for a marked decline in teliospore germination between sampling years. There was some evidence of a decrease in germination with increasing depth in the UK, and for some time‐depth interactions. After 3 years’ incubation (Experiment 1), mean teliospore recovery and mean germination were: UK: 61% recovery and 31% (33%) germination for T0 (and T3); Italy: 30% recovery and 36% (29%) germination; and Norway: 12% recovery and 19% (49%) germination. Germination for laboratory controls ranged from 20–59% (UK), 18–41% (Italy) and 28–59% (Norway). There was no evidence for burial‐induced dormancy except in Norway. Teliospores of T. indica can survive for at least three years in European soils. This prolonged period of survival could support establishment of the pathogen if it were introduced into areas of European cereal production.
A Novel Modification of a Flow Cytometric Assay of Phosphorylated STAT1 in Whole Blood Monocytes for Immunomonitoring of Patients on IFNα Regimen
Authors: Vakkila J. , Nieminen U. , Siitonen S. , Turunen U. , Halme L. , Nuutinen H. , Mustonen H. , Puolakkainen P. , Färkkilä M. , Repo H. 
Published: November 2007

AbstractWe explored whether episodes stimulating leucocytes in vivo could be tracked from whole blood samples by monitoring activation of STAT1 by flow cytometry. The method was tested in hepatitis C patients (n = 9) that were on interferon (IFN)α regimen. CD14+ monocytes responded strongly to IFNα/γ being sensitive indicators for recent immune activation. At 45 min after s.c. IFNα 91% of monocytes were phosphorylated STAT1+. The frequency of responding cells decreased to a base level within 6 h. Monocytes, however, had a long‐term deficient phosphorylated STAT1 response to IFNαin vitro that in patients on standard IFNα regimen lasted for 48 h. In patients on pegylated IFNα the phosphorylated STAT1 response was completely absent. We conclude that whole blood analysis of STAT1 activation by flow cytometry is applicable to monitor immune cells in patient material.
Critical Role of Qa1b in the Protection of Mature Dendritic Cells from NK Cell‐Mediated Killing
Authors: Persson C. M. , Assarsson E. , Vahlne G. , Brodin P. , Chambers B. J. 
Published: November 2007

AbstractMolecular interactions in natural killer (NK) cell‐mediated killing of dendritic cells (DC) have under recent years come under scrutiny. Upon stimulation with IFN‐γ or lipopolysaccharide, DC become relatively resistant to NK cell‐mediated lysis. In the present study, we investigated the role of Qa1b on DC and its receptor NKG2A on NK cells in the protection of mature DC from NK cells. We demonstrate that while both NKG2A+ and NKG2A‐ NK cells can efficiently lyse unstimulated DC, NKG2A+ NK cells but not NKG2A‐ NK cells are largely impaired in their ability to lyse mature DC. Similarly, mature DC from mice expressing H‐2Db, whose leader peptide sequence binds and stabilizes Qa1b, were resistant to NK cell‐mediated killing, suggesting that stable Qa1b expression contributes to the protection of mature DC. This finding was further validated by the demonstration that addition of the Qdm leader peptide could protect TAP1‐/‐ DC from NK cell‐mediated lysis both in vitro and in vivo. The present data suggest that stable expression of Qa1 on the surface of mature DC contributes to the protection of DC from NK cell‐mediated lysis.
Alterations in Antral Cytokine Gene Expression in Peptic Ulcer Patients During Ulcer Healing and After Helicobacter pylori Eradication
Authors: Goll R. , Cui G. , Olsen T. , Isaksen V. , Gruber F. , Husebekk A. , Florholmen J. 
Published: November 2007

AbstractEarlier studies have shown that the antral immune response in Helicobacter pylori infection has a mixed Th1‐Th2‐T‐regulatory profile. After eradication, a chronic inflammation remains in some patients, but a follow‐up study with a comprehensive cytokine profile in has not previously been published. Twelve patients with H. pylori positive peptic ulcer disease (five antral and seven duodenal) were enrolled and cytokine gene expressions in antral biopsies were determined (1) at entry, (2) after resolving the ulcer with proton pump inhibitor (PPI) treatment and (3) after eradication. The second endoscopy was performed 4 weeks after ending the PPI treatment, and the third endoscopy was performed after a mean of 10 months after eradication. Inflammation was graded according to the updated Sydney system. Interleukin (IL)1β, IL8, IL12A, IL18, TNFα, IFNγ, IL4, IL6 and IL10 expression levels were analysed by real‐time RT‐PCR. Mixed mononuclear and neutrophil infiltrates were seen at entry and after ulcer healing. After eradication, low‐grade mononuclear infiltrates were found. The cytokine expression levels after ulcer healing (H. pylori positive gastritis) were not significantly different from the levels at entry (ulcer). After eradication, attenuation of the Th1 cytokines except for TNFα and a persisting increase of IL4 levels were observed, whereas the IL10 expression was markedly reduced. The present data did not indicate a specific ulcer promoting cytokine gene regulation profile. However, after eradication a chronic low‐grade inflammation was seen with reduced Th1, prolonged Th2 and disappearance of the T‐regulatory response.
Ediacaran in Uruguay: palaeoclimatic and palaeobiological implications
Authors: PECOITS ERNESTO , GINGRAS MURRAY , AUBET NATALIE , KONHAUSER KURT 
Published: November 2007

AbstractThe Ediacaran to lowermost Cambrian successions of south‐eastern Uruguay preserve an unusual and significant record of deposits generated during the Gondwana assembly (ca 590 to 535 Ma). This study presents a review of data obtained through extensive field‐based mapping coupled with detailed sedimentology and stratigraphy of key formations. The geological units within the study area consist of the Maldonado Group (Playa Hermosa, Las Ventanas and San Carlos formations), the Arroyo del Soldado Group (Yerbal, Polanco Limestones, Barriga Negra and Cerro Espuelitas formations) and the Arroyo de la Pedrera Group (Piedras de Afilar and Cerro Victoria formations). The Maldonado Group is characterized by a glacially influenced volcanogenic‐sedimentary sequence with ice‐rafted debris and dropstones in the Playa Hermosa and Las Ventanas formations. The Arroyo del Soldado Group is a mixed siliciclastic‐carbonate succession, mainly represented by an intercalation of basal pink dolostones, banded siltstones, rhythmites of dolostone‐limestone, iron formations, cherts and conglomerates. Carbonates in the Polanco Limestones Formation are characterized by a negative δ13C excursion up to −3·26‰ PeeDeeBelemnite. The Arroyo de la Pedrera Group consists of quartz arenites and stromatolitic/oolitic dolostones. Preliminary data indicate that the Precambrian–Cambrian could be contained within or at the base of this group. The entire succession is almost 6000 m thick, and contains a rich fossil assemblage composed of organic‐walled microfossils and small shelly fauna, including the index fossil Cloudina riemkeae. The stratigraphic and chemostratigraphic features are suggestive of a Gaskier age (ca 580 Ma) for the basal glacial‐related units. In this scenario, the results show the importance of lithostratigraphic, biostratigraphic and chemostratigraphic data of these Ediacaran units in the global correlation of terminal Proterozoic sedimentary rocks.
The level of matrix metalloproteinase‐2 in donor plasma strongly correlates with post‐transfusion recovery of stored platelet concentrates
Authors: Mutlu A. , Allen D. J. , Freedman J. , Leytin V. 
Published: November 2007

Background and Objective  A simple test accurately predicting post‐transfusion recovery of stored platelet concentrates (PCs) is needed.Materials and Methods  Matrix metalloproteinase‐2 (MMP‐2) was determined in fresh‐frozen plasma of normal donors using enzyme‐linked immunosorbent assay (ELISA)‐based assay. Post‐transfusion recovery of human PCs was determined in rabbits with an inhibited reticuloendothelial system by flow cytometry.Results  We demonstrated a strong positive (r = 0·91) and highly significant (P = 0·0015) correlation between the concentration of MMP‐2 in plasma of normal donors and post‐transfusion recovery of PCs stored for 5 days at 22 °C under standard blood banking conditions. A higher level of donor plasma MMP‐2 is associated with improved recovery of transfused platelets.Conclusion  These observations suggest that pre‐transfusion MMP‐2 assay of donor's plasma may be a predictor of post‐transfusion recovery of PCs. However, the usefulness of this assay should be elucidated in clinical transfusion settings.
Agonistic Support in Juvenile Japanese Macaques: Cognitive and Functional Implications
Authors: Schino Gabriele , Tiddi Barbara , Sorrentino Eugenia Polizzi di 
Published: November 2007

AbstractAgonistic support is generally considered a classical example of altruistic behaviour. It plays a critical role in the process of rank acquisition. This study investigates agonistic coalitions involving juvenile Japanese macaques (Macaca fuscata) living in a large captive group. Kinship was a good predictor of agonistic support received by juvenile macaques. Kinship also had a significant, though weaker, influence on agonistic support given by juvenile macaques. The latter was strongly influenced by the prospective rank of the individual against which the coalition was directed, i.e. by the rank relationship between the target of the coalition and the juvenile’s mother. Juvenile macaques intervened aggressively more against prospectively subordinate individuals than against prospectively dominant individuals. These results imply agonistic support is not necessarily altruistic, and support the hypothesis that primates may understand the rank relationship that exist among their group mates, i.e. that they are aware of third‐party social relationships. They also suggest that selective pressures associated with the process of rank acquisition may have favoured the evolution of higher cognitive abilities.
Reproductive Asynchrony and the Divergence of Hawaiian Crickets
Authors: Danley Patrick D. , DeCarvalho Tagide N. , Fergus Daniel J. , Shaw Kerry L. 
Published: November 2007

AbstractAsynchrony in reproductive behavior may contribute to reproductive isolation among sympatric species. While the 38 cryptic species of the genus Laupala are primarily distinguished on the basis of variation in pulse rate of male calling songs, additional phenotypes, such as asynchrony in reproductive behavior, may contribute to reproductive isolation in this genus. Here we document similarities and differences in the diel timing of two reproductive behaviors, male singing activity and insemination events. Asynchrony in the diel timing of male singing behavior was observed between two sympatric species, Laupala cerasina and Laupala paranigra, in the field. An interpopulational comparison within L. cerasina did not reveal variation in diel behavior patterns of singing between two locations. Asynchrony in the timing of copulation and sperm transfer between L. cerasina and L. paranigra was documented in the laboratory. The observed pattern of asynchrony in both the field and laboratory could have arisen in a number of ways. One possibility is that species diverged in sympatry because of interspecific interactions, producing a pattern of reproductive character displacement. Alternatively, the observed asynchrony in reproductive behavior may have played a role in the process of community assembly within this recently diverged cricket genus. The presence of interspecific variation and the absence of intraspecific variation revealed by our study do not support a pattern of reproductive character displacement for diel reproductive behavior, suggesting that the differences seen between species were not caused by recent species interactions.
Methods for inoculum production and inoculation of Cistella japonica, the causal agent of resinous stem canker in Chamaecyparis obtusa
Authors: Yamanobe T. , Oribe Y. , Nishimura K. 
Published: November 2007

SummaryThe ascomycete Cistella japonica was cultured on potato dextrose agar medium (PDA) for inoculation into Chamaecyparis obtusa, enabling the development of an inoculation method suitable for use in a breeding programme aimed at selecting for families of Ch. obtusa resistant to resinous stem canker. Using PDA to generate the inoculum resolved the problems encountered with the previously used mixed medium of rice bran and wheat bran, including unfavourable characteristics, uncertain growth of Ci. japonica mycelia, and a complex culturing operation. The inoculation test induced resin exudation similar to that observed in natural infections, and reproduced clonal differences with regard to damage severity.
The effect of cerium on high‐cycle fatigue properties of die‐cast magnesium alloy
Authors: YANG Y. , LIU Y. B. 
Published: November 2007

ABSTRACTThe effect of cerium (Ce) on high‐cycle fatigue behaviour of die‐cast magnesium alloy AZ91D was investigated. Mechanical fatigue tests were conducted at the stress ratio, R= 0.1 on specimens of AZ91D alloys with different Ce additions. The microstructure and fatigue fracture surfaces of specimens were examined using a scanning electron microscope (SEM) to reveal the micromechanisms of fatigue crack initiation and propagation. The results show that the grain size of AZ91D is refined, and the amount of porosity decreases and evenly distributes with the addition of Ce. The fatigue strength of AZ91D evaluated by the up‐and‐down load method increases from 96.7 MPa to 116.3 MPa (1% Ce) and 105.5 MPa (2% Ce), respectively. The fatigue cracking of AZ91D alloy initiates at porosities and inclusions of the alloy's interior, and propagates along the grain boundaries. The fatigue fracture surface of test specimens shows the mixed fracture characteristics of quasi‐cleavage and dimple.
Off‐axis fatigue cracking behaviour in notched fibre metal laminates
Authors: CHANG P.‐Y. , YANG J.‐M. , SEO H. , HAHN H. T. 
Published: November 2007

ABSTRACTThe off‐axis fatigue cracking behaviour of notched fibre metal laminates under constant amplitude loading conditions was investigated experimentally and numerically. It was found that the off‐axis fatigue crack initiation life decreased as the off‐axis angles increased. This indicated that the off‐axis laminates raised the applied stress level in the aluminium (Al) layer and subsequently resulted in earlier cracking in the Al layer. The off‐axis fatigue crack initiation lives of notched fibre metal laminates were predicted using lamination theory and an energy‐based critical plane fatigue damage analysis from the literature.After a crack initiated in the Al layer, it was observed that the crack path angles of the off‐axis specimens were neither perpendicular to the fibre nor to the loading direction. A finite‐element model was established for predicting the crack path angles.
Influence of sub‐micrometer notches on the fracture of single crystal silicon thin films
Authors: LI X. , KASAI T. , NAKAO S. , ANDO T. , SHIKIDA M. , SATO K. 
Published: November 2007

ABSTRACTThe influence of notches on the fracture of single crystal silicon thin films was investigated. The tests were conducted on notched and smooth tensile specimens micromachined on a silicon wafer. The specimen geometry was 100 μm long, 50 μm wide and 5 μm thick. For the notched specimen, a V‐shaped sub‐micrometer notch was introduced on one edge of it by using a focused ion beam (FIB) process. The notch lengths ranged from 0.07 to 1.3 μm. Four types of specimens with different surfaces and tensile orientations were tested. The smooth specimens showed scattered fracture strengths and ‘collapsed’ fractures. For the restrictive‐shaped notches, the critical length was 0.5 μm. The short‐notched (<0.5 μm) specimens also showed ‘collapsed’ fractures, and the stress concentrations on notch tips decreased their fracture strengths. For the long‐notched (>0.5 μm) specimens, the notch was equivalent to a crack in the Griffith model and the crack mainly propagated on {111} cleaved planes.
Fatigue failure prediction of press fitted parts subjected to a cyclic loading condition by finite element methods
Authors: KANG W. J. , KIM A. K. , KIM G. H. 
Published: November 2007

ABSTRACTThe lower control arm is one of the most important components and constrains the longitudinal and vertical movements of the wheel relative to the vehicle. Recently, aluminium alloy has become a constituent material of the arm instead of steel in order to reduce the weight of the vehicle. As a cyclic external load is applied to the ball joint of the arm, the contact force between the steel bush housing and the aluminium arm joined by the press fitting varies through the deformation of the rubber bush. The oscillatory contact force between these components could determine the life of the aluminium alloy arm. Indeed, the failure of the arm was observed at the bush mount where fretting is expected. In this study, nonlinear finite element simulations were carried out to investigate the cause of the failure. As a result, it turned out that the failure of the mount was associated with the fretting introduced by the press fitting and the cyclic stress due to the oscillatory contact force by external cyclic loads. In addition, the failure location and lifetime of the aluminium alloy arm were predicted based on a damage analysis.
Non‐local stress approach for fatigue assessment based on weakest‐link theory and statistics of extremes
Authors: WORMSEN A. , SJÖDIN B. , HÄRKEGÅRD G. , FJELDSTAD A. 
Published: November 2007

ABSTRACTIn the present paper a non‐local stress approach for fatigue assessment based on weakest‐link theory and statistics of extremes is presented. It is a non‐local stress approach in the sense that it takes the complete stress field into account rather than just the highest local stress. The statistical distribution of fatigue strength data from smooth standard specimens serves as a starting point for the computation of the probability of fatigue failure of a mechanical component under cyclic loading. The probability of fatigue failure can be obtained by post‐processing results from a standard finite element stress analysis. It is shown that the non‐local stress approach can be linked to the probability of finding the fatigue critical defect in the most highly stressed volume of the component. A numerical procedure is presented that is fully compatible with the results from a standard finite element stress analysis. It is further shown how the fatigue strength distribution can be transformed into a fatigue life distribution by using Basquin's equation. Finally, the non‐local stress approach is used for predicting the fatigue limit of several specimens and predictions are compared with test results.