bluuebunny/crossref_metadata_2025_split huggingface dataset:
The β‐1,3‐glucanosyltransferase gas4p is essential for ascospore wall maturation and spore viability in Schizosaccharomyces pombe
Authors: De Medina‐Redondo María , Arnáiz‐Pita Yolanda , Fontaine Thierry , Del Rey Francisco , Latgé Jean Paul , De Aldana Carlos R. Vázquez 
Published: April 2008

SummaryMeiosis is the developmental programme by which sexually reproducing diploid organisms generate haploid gametes. In yeast, meiosis is followed by spore morphogenesis. The formation of the Schizosaccharomyces pombe ascospore wall requires the co‐ordinated activity of enzymes involved in the biosynthesis and modification of its components, such as glucans. During sporogenesis, the β‐1,3‐glucan synthase bgs2p synthesizes linear β‐1,3‐glucans, which remain unorganized and alkali‐soluble until covalent linkages are set up between β‐1,3‐glucans and other cell wall components. Several proteins belonging to the glycoside hydrolase family 72 (GH72) with β‐1,3‐glucanosyltransferase activity have been described in other organisms, such as the Saccharomyces cerevisiae Gas1p or the Aspergillus fumigatus Gel1p. Here we describe the characterization of gas4+, a new gene that encodes a protein of the GH72 family. Deletion of this gene does not lead to any apparent defect during vegetative growth, but homozygous gas4Δ diploids show a sporulation defect. Although meiosis occurs normally, ascospores are unable to mature or to germinate. The expression of gas4+ is strongly induced during sporulation and a yellow fluorescent protein (YFP)–gas4p fusion protein localizes to the ascospore periphery during sporulation. We conclude that gas4p is required for ascospore maturation in S. pombe.
kinC/D‐mediated heterogeneous expression of spo0A during logarithmical growth in Bacillus subtilis is responsible for partial suppression of φ29 development
Authors: Castilla‐Llorente Virginia , Salas Margarita , Meijer Wilfried J. J. 
Published: April 2008

SummaryThe host of the lytic bacteriophage φ29 is the spore‐forming bacterium Bacillus subtilis. When infection occurs during early stages of sporulation, however, φ29 development is suppressed and the infecting phage genome becomes trapped into the developing spore. Recently, we have shown that Spo0A, the key transcriptional regulator for entry into sporulation, is directly responsible for suppression of the lytic φ29 cycle in cells having initiated sporulation. Surprisingly, we found that φ29 development is suppressed in a subpopulation of logarithmically growing culture and that spo0A is heterogeneously expressed during this growth stage. Furthermore, we showed that kinC and, to a minor extent, kinD, are responsible for heterogeneous expression levels of spo0A during logarithmical growth that are below the threshold to activate sporulation, but sufficient for suppression of the lytic cycle of φ29. Whereas spo0A was known to be heterogeneously expressed during the early stages of sporulation, our findings show that this also occurs during logarithmical growth. These insights are likely to have important consequences, not only for the life cycle of φ29, but also for B. subtilis developmental processes.
The receiver domain of FrzE, a CheA–CheY fusion protein, regulates the CheA histidine kinase activity and downstream signalling to the A‐ and S‐motility systems of Myxococcus xanthus
Authors: Inclán Yuki F. , Laurent Sophie , Zusman David R. 
Published: April 2008

SummaryThe Frz chemosensory system is a two‐component signal transduction pathway that controls cell reversals and directional movements for the two motility systems in Myxococcus xanthus. To trigger cell reversals, FrzE, a hybrid CheA–CheY fusion protein, autophosphorylates the kinase domain at His‐49, and phosphoryl groups are transferred to aspartate residues (Asp‐52 and Asp‐220) in the two receiver domains of FrzZ, a dual CheY‐like protein that serves as the pathway output. The role of the receiver domain of FrzE was unknown. In this paper, we characterize the FrzE protein in vitro and show that the receiver domain of FrzE negatively regulates the autophosphorylation activity of the kinase domain of FrzE. Unexpectedly, it does not appear to play a direct role in phospho‐relay as in most other histidine kinase receiver domain hybrid systems. The regulatory role of the FrzE receiver domain suggests that it may interact with or be phosphorylated by an unknown protein. We also show the dynamics of motility system‐specific marker proteins in FrzE mutants as cells move forward and reverse. Our studies indicate that the two motility systems are functionally co‐ordinated and that any system‐specific branching of the pathway most likely occurs downstream of FrzE.
Luminous K-band selected quasars from UKIDSS
Authors: Maddox Natasha , Hewett Paul C. , Warren S. J. , Croom S. M. 
Published: April 2008

Abstract
The largest K-band flux-limited sample of luminous quasars to date has been constructed from the UKIRT (UK Infrared Telescope) Infrared Deep Sky Survey (UKIDSS) Large Area Survey Early Data Release, covering an effective area of 12.8 deg2. Exploiting the K-band excess (KX) of all quasars with respect to foreground stars, including quasars experiencing dust reddening and objects with non-standard spectral energy distributions (SEDs), a list of targets suitable for spectroscopic follow-up observations with the AAOmega multi-object spectrograph is constructed, resulting in more than 200 confirmed active galactic nuclei (AGN). KX selection successfully identifies as quasar candidates objects that are excluded from the Sloan Digital Sky Survey (SDSS) quasar selection algorithm due to their colours being consistent with the stellar locus in optical colour space (with the space density of the excluded objects agreeing well with results from existing completeness analyses). Nearly half of the KX-selected quasars with K≤ 17.0 at z &lt; 3 are too faint in the i band to have been targeted by the SDSS quasar selection algorithm, revealing a large population of quasars with red i−K colours. The majority of these objects have significant amounts of host galaxy light contributing to their K-band magnitudes, consistent with previous predictions. The remaining objects are morphologically stellar and have colours consistent with quasars experiencing Small Magellanic Cloud (SMC)-type reddening with 0.10 &lt; E(B−V) &lt; 0.25. The i−K colour distribution indicates that &lt;10 per cent of the quasar population is missing from this K-band selected sample due to dust reddening, and comparisons with simulations strongly favour an obscured fraction of &lt;20 per cent. Photometric redshifts and classifications are computed for the candidates that were not observed spectroscopically. For the extended objects whose colours are consistent with those of a reddened quasar, models of galaxy surface brightness profiles appropriate for each object are used to eliminate the possibility of the presence of a nuclear source bright enough for inclusion in a K≤ 17.0 quasar sample. The effectiveness of near-infrared colour selection of quasars has been demonstrated by this modest-sized sample, and it will only become more apparent as the amount of available data increases.
Homogeneous studies of transiting extrasolar planets – I. Light-curve analyses
Authors: Southworth John 
Published: April 2008

Abstract
I present a homogeneous analysis of the transit light curves of 14 well-observed transiting extrasolar planets. The light curves are modelled using jktebop, random errors are measured using Monte Carlo simulations and the effects of correlated noise are included using a residual-permutation algorithm. The importance of stellar limb darkening on the light-curve solutions and parameter uncertainties is investigated using five different limb darkening laws and including different numbers of coefficients as fitted parameters. The linear limb darkening law cannot adequately fit the Hubble Space Telescope (HST) photometry of HD 209458, but the other four laws give very similar results to each other for all transit light curves. In most cases fixing the limb darkening coefficients at theoretically predicted values does not bias the results, but does cause the error estimates to be too small. The available theoretical limb darkening coefficients clearly disagree with empirical values measured from the HST light curves of HD 209458; limb darkening must be included as fitted parameters when analysing high-quality light curves.
In most cases the results of my analysis agree with the values found by other authors, but the uncertainties I find can be significantly larger (by factors of up to 3). Despite these greater uncertainty estimates, the analyses of sets of independent light curves for both HD 189733 and HD 209458 lead to results which do not agree with each other. This discrepancy is worst for the ratio of the radii (6.7σ for HD 189733 and 3.7σ for HD 209458), which depends primarily on the depth of the transit. It is therefore not due to the analysis method but is present in the light curves. These underlying systematic errors cannot be detected from the reduced data alone unless at least three independent light curves are available for an individual planetary system.
The surface gravities of transiting extrasolar planets are known to be correlated with their orbital periods. New surface gravity values, calculated from the light-curve results and the stellar spectroscopic orbits, show that this correlation is still present. New high-precision light curves are needed for HD 149026, OGLE-TR-10, OGLE-TR-56, OGLE-TR-132 and GJ 436, and new radial velocity curves for the XO-1, WASP-1, WASP-2 and the OGLE (Optical Gravitational Lensing Experiment) planetary systems.
Toll‐like Receptor Cross‐hyporesponsiveness is Functional in Interleukin‐1‐receptor‐associated Kinase‐1 (IRAK‐1)‐deficient Macrophages: Differential Role Played by IRAK‐1 in Regulation of Tumour Necrosis Factor and Interleukin‐10 Production
Authors: Berglund M. , Thomas J. A. , Hörnquist E. H. , Hultgren O. H. 
Published: April 2008

AbstractSignalling downstream Toll‐like receptors (TLR) is regulated at several levels in order to activate the immune response and prevent excessive inflammation. Altered intracellular signalling may be one reason that repeated stimulation of various TLRs results in hyporesponsiveness and cross‐tolerance. We report that TLR cross‐tolerance is inducible in the absence of interleukin‐1 receptor‐associated kinase‐1 (IRAK‐1) in peritoneal macrophages. Similar to wild‐type macrophages, IRAK‐1‐deficient macrophages respond with decreased tumour necrosis factor (TNF) production to a secondary TLR stimulation, but in opposite to IRAK‐1+/+, IRAK‐1−/− macrophages display increased interleukin (IL)‐10 production at TLR restimulation. IRAK‐1‐deficient peritoneal macrophages have a defective TNF and IL‐10 production in response to lipoteichoic acid stimulation as well as a defective IL‐10‐but a normal TNF production in response to high concentration of lipopolysaccharide. Our results demonstrate that IRAK‐1 is not necessary for induction of TLR cross‐tolerance as judged by TNF production.
Prolonged Eosinophil Production after Allergen Exposure in IFN‐γR KO Mice is IL‐5 Dependent
Authors: Zhao L.‐L. , Lötvall J. , Lindén A. , Tomaki M. , Sjöstrand M. , Bossios A. 
Published: April 2008

AbstractAsthma is a T helper 2 (Th2)‐driven inflammatory process characterized by eosinophilia. Prolonged airway eosinophilia is commonly observed in asthma exacerbations. Our aim was to evaluate whether eosinophilia in prolonged allergic inflammation is associated with a continuous supply of new eosinophils to the airways, and how this is regulated. Ovalbumin (OVA)‐sensitized interferon‐γ receptor knockout mice (IFN‐γR KO), known to maintain a long‐lasting eosinophilia after allergen exposure, were compared to wild type (wt) controls. Animals were exposed to OVA or phosphate‐buffered saline on three consecutive days, and bone marrow (BM), blood and bronchoalveolar lavage (BAL) samples were collected 24 h, 7 and 21 days later. Newly produced cells were labelled using bromodeoxyuridine (BrdU). Serum IL‐5 was measured and its role was investigated by administration of a neutralizing anti‐IL‐5 antibody. In‐vitro eosinophilopoiesis was examined in both groups by a colony‐forming assay. Allergen challenge increased eosinophils in BM, blood and BAL, in both IFN‐γR KO and wt mice, both 24 h and 7 days after the last allergen exposure. At 21 days after the last exposure, only IFN‐γR KO mice maintained significantly increased eosinophil numbers. Approximately 50% of BAL granulocytes in IFN‐γR KO were produced during the last 6 days. Interleukin (IL)‐5 concentration was increased in IFN‐γR KO mice, and anti‐IL‐5 reduced eosinophil numbers in all compartments. Increased numbers of eosinophil colonies were observed in IFN‐γR KO mice after allergen exposure versus controls. In this model of a Th2‐driven prolonged allergic eosinophilia, new eosinophils contribute to the extended inflammation in the airways by enhanced BM eosinophilopoiesis in an IL‐5‐dependent manner.
Aire Deficiency Causes Increased Susceptibility to Streptozotocin‐induced Murine Type 1 Diabetes
Authors: Hässler S. , Peltonen L. , Sandler S. , Winqvist O. 
Published: April 2008

AbstractAire‐deficient mice are a model of the human monogenic disorder autoimmune polyendocrine syndrome type I (APS I) characterized by a progressive autoimmune destruction of multiple endocrine glands such as the adrenal cortex, the parathyroids and the β‐cells of the pancreas. The disease is caused by mutations in the autoimmune regulator (AIRE) gene, a putative transcription factor expressed in thymic medullary epithelial cells and in antigen‐presenting cells of the myeloid lineage in peripheral lymphoid organs. As Aire−/− mice do not spontaneously develop endocrinopathies, we wanted to evaluate the autoimmune multiple low‐dose streptozotocin (MLDSTZ) diabetes model in Aire−/− mice. Surprisingly, Aire heterozygote mice were most susceptible to MLDSTZ‐induced diabetes, whereas Aire−/− mice displayed an intermediate sensitivity to diabetes. Furthermore, Aire−/− macrophages produced higher levels of TNF‐α and lower levels of IL‐10 following streptozotocin stimulation, and Aire−/− mice developed a higher frequency of islet cells autoantibodies as a sign of increased activation. However, the number of islet infiltrating F4/80+ Aire−/− macrophages was significantly decreased which was attributed to an increased susceptibility to streptozotocin cytotoxicity of Aire−/− macrophages. In conclusion, Aire−/− macrophages display an increased activation after STZ stimuli, but suffer from increased susceptibility to STZ cytotoxicity. These results support an important function of Aire in the control of peripheral tolerance through myeloid antigen‐presenting cells.
Diffuse cutaneous mastocytosis in a newborn calf
Authors: Palyada Kiran S. , Scott Danny W. , Schlafer Donald H. , Czajkowski Melissa 
Published: April 2008

AbstractPreviously reported cases of congenital cutaneous mast cell tumours in calves were characterized by multiple discrete nodules. The calf presented herein is, to the authors’ knowledge, the first documented case of congenital diffuse cutaneous mastocytosis. The entire skin was thickened and wrinkled with particularly prominent skin folds on the head, ventrum, and legs. Histological examination of two haired skin specimens (eyelid, muzzle margin) revealed that the dermis was diffusely infiltrated by sheets of neoplastic mast cells.
Cornification defect in the Golden retriever: clinical, histopathological, ultrastructural and genetic characterisation
Authors: Cadiergues Marie‐Christine , Patel Anita , Shearer David H. , Fermor Ruth , Miah Suhel , Hendricks Anke 
Published: April 2008

AbstractVeterinarians have recognised a nonpruritic skin disease in the Golden retriever breed characterised by excessive scaling of large, variably pigmented flakes of skin in otherwise healthy dogs. This prospective case series describes clinical, histopathological, ultrastructural and genetic features of this cornification defect in 17 affected dogs. The condition affects young dogs of either sex and is characterised by symmetrical, predominantly ventro‐lateral scaling and hyperpigmentation of the trunk. Histopathological and ultrastructural changes of the stratum corneum are suggestive of delayed degradation of corneodesmosomes. A genetic aetiology is proposed and a single‐trait autosomal recessive mode of inheritance discussed.
Role of sucrose in the fitness of Streptococcus mutans
Authors: Kreth J. , Zhu L. , Merritt J. , Shi W. , Qi F. 
Published: April 2008

Introduction:  Dental caries has been closely linked to fermentable carbohydrates as key environmental factors. Sucrose has been identified as the most cariogenic carbohydrate. Streptococcus mutans, considered to be the primary pathogen causing dental caries, is able to utilize sucrose as a nutrient source, partially for the production of intracellular storage components and for the production of extracellular glucans via the glucosyltransferases GtfB, GtfC, and GtfD. The following study explores the competitiveness and fitness of S. mutans when grown with different concentrations of sucrose.Methods:  Growth competition with oral streptococci and antimicrobial susceptibility in static biofilm models grown without sucrose or with 0.1% or 0.5% sucrose were investigated using confocal laser scanning microscopy. The numbers of surviving S. mutans of both wild‐type and an isogenic Gtf‐negative mutant after antimicrobial treatment were determined as colony‐forming units.Results:  S. mutans was able to establish microcolonies with increasing sucrose concentration in the presence of other streptococcal competitors during biofilm development. The antimicrobial susceptibility decreased when sucrose was available as substrate and was dependent on the presence of the Gtfs.Conclusion:  The increased resistance against antimicrobial treatment was associated with the availability of sucrose, but was not influenced much by the concentration used during this study. The resistance was strongly associated with the Gtf activity, excluding any intracellular metabolic effect of sucrose in the resistance mechanism.
Functional impairment as a predictor of short‐term symptom course in bipolar I disorder
Authors: Weinstock Lauren M , Miller Ivan W 
Published: April 2008

Objectives:  Most prior research has focused on functional impairment as a consequence, rather than a predictor, of mood symptoms in bipolar disorder (BD). Yet the majority of this research has been cross‐sectional, thus limiting conclusions regarding directionality of effects. Indeed, just as functional impairment may represent an important outcome of BD, it may also serve as a risk factor for future affective symptoms or episodes. Thus, the primary aim of this study was to evaluate functional impairment as a predictor of mood symptoms in BD.Methods:  Ninety‐two patients with bipolar I disorder, recruited from hospital settings, were administered the Modified Hamilton Rating Scale for Depression, Bech–Rafaelson Mania Scale, and UCLA Social Attainment Survey (SAS) at baseline and at four‐month follow‐up.Results:  Overall, patients evidenced a moderate level of functional impairment at both time points. Whereas baseline functional impairment was not associated with subsequent manic symptoms, baseline functional impairment was significantly predictive of depressive symptom levels at four‐month follow‐up. When individual SAS subscales were evaluated, impaired romantic relationship functioning and activity involvement were each significantly predictive of subsequent depressive symptoms, whereas baseline peer functioning was not.Conclusions:  The study results suggest that functional impairment may be predictive of subsequent depressive, but not manic, symptoms over a relatively short‐term follow‐up period. Future studies that evaluate illness course over longer follow‐up periods would be useful to further clarify the potential bidirectional relationship between depression and functional impairment in BD.
Lamotrigine in bipolar disorder: efficacy during pregnancy
Authors: Newport D Jeffrey , Stowe Zachary N , Viguera Adele C , Calamaras Martha R , Juric Sandra , Knight Bettina , Pennell Page B , Baldessarini Ross J 
Published: April 2008

Objective:  Clinical management of bipolar disorder (BPD) patients during pregnancy is a major challenge. The high risk of bipolar depression during pregnancy encourages consideration of lamotrigine (LTG). We therefore compared recurrence risks among pregnant women with BPD treated with LTG to those discontinuing mood stabilizer therapies.Methods:  We compared risks and weeks to new DSM‐IV illness‐episodes among 26 initially clinically stable pregnant women diagnosed with DSM‐IV BPD who continued LTG treatment to those discontinuing all mood stabilizer treatment during pregnancy.Results:  The risk of new illness‐episodes with LTG was 30% versus 100% after discontinuing mood stabilizers, and survival‐computed time‐to‐25%‐recurrence was 28.0 versus 2.0 weeks (χ2 = 17.3, p < 0.0001; hazard ratio = 12.1; 95% confidence interval = 1.6–91.7).Conclusions:  Discontinuing mood stabilizer treatment presents high risks of illness‐recurrence among pregnant women diagnosed with BPD. LTG may afford protective effects in pregnancy, and its reported fetal safety compares favorably to other agents used to manage BPD.
Effect of Photosynthetic Inhibitors on Induction of Tryptamine Pathway‐mediated Resistance in Lesion Mimic Mutant of Rice Infected with Magnaporthe grisea
Authors: Imaoka A. , Ueno M. , Kihara J. , Arase S. 
Published: April 2008

AbstractRice cv. Sekiguchi‐asahi was identified as a lesion mimic mutant from cv. Asahi. This mutant showed light‐enhanced resistance to Magnaporthe grisea infection, inducing Sekiguchi lesion (sl) formation and tryptamine accumulation. To elucidate the role of chloroplasts on the activation of tryptamine pathway, the effect of some photosynthetic inhibitors on light‐dependant Sekiguchi lesion formation, tryptamine accumulation, and enzyme activities was investigated. When detached leaf blades which had been pretreated with Linuron, 1, 10‐Phenanthroline or Poly‐l‐lysine were inoculated with M. grisea, respectively, Sekiguchi lesion formation and typtamine accumulation were suppressed even under light, suppressing gene expression of tryptophan decarboxylase and monoamine oxidase activity. On the other hand, catalase activity was significantly inhibited in control leaves infected with M. grisea under light, but kept at high level in chemical‐pretreated leaves. These results suggested that photosynthetic activity in chloroplasts was involved in inhibition of antioxidant sysytem and activation of tryptamine pathway responsible for light‐enhanced resistance in sl mutant to M. grisea infection.