bluuebunny/crossref_metadata_2025_split huggingface dataset:
Roles of virulence genes (PsaA and CpsA) on the invasion of Streptococcus pneumoniae into blood system
Authors: Hu Da-kang , Wang Dong-guo , Liu Yang , Liu Chi-bo , Yu Lian-hua , Qu Ying , Luo Xin-hua , Yang Jin-hong , Yu Jian , Zhang Jin , Li Xiang-yang 
Published: May 2013

Abstract

Background

Streptococcus pneumoniae (SP) is the major cause of childhood mortality worldwide, we need to understand virulence genes of SP so can better target the treatment.
We investigated the expression of virulence genes PsaA and CpsA in different strains of SP interacting with monocyte cell line (THP-1) or pneumocyte cell line (A549) and the possible mechanism of SP invasion of the blood system.

Methods
A total of 23 strains of SP were collected from hospitalized patients (blood-derived and sputum-derived) in the Second Affiliated Hospital of Wenzhou Medical College. The strains and ATCC 49619 were cultured, and RNAs were extracted. THP-1 and A549 cells were stimulated by different SP and ATCC 49619 for 4 h and 8 h, respectively. Quantitative real-time PCR was used to analyze the mRNA expression of PsaA and CpsA. The data were analyzed by SPSS 17.0.

Results
The mRNA level of PsaA and CpsA were all significantly increased in clinical SP strains when compared to ATCC49619 after tedTHP-1 and A549 cells were stimulated. Clinical SPs showed higher virulence compared with ATCC49619.

Conclusions
The expression of CpsA is the basis of the pathogenicity of SP. The expression of virulence gene PsaA may be helpful to the invasion of SP to the blood system.
5′-AMP impacts lymphocyte recirculation through activation of A2B receptors
Authors: Bouma Hjalmar R , Mandl Judith N , Strijkstra Arjen M , Boerema Ate S , Kok Jan-Willem , van Dam Annie , IJzerman Ad , Kroese Frans G M , Henning Robert H 
Published: May 2013

ABSTRACT
Natural hibernation consists of torpid phases with metabolic suppression alternating with euthermic periods. Induction of torpor holds substantial promise in various medical conditions, including trauma, major surgery, and transplantation. Torpor in mice can be induced pharmacologically by 5′-AMP. Previously, we showed that during natural torpor, the reduction in body temperature results in lymphopenia via a reduction in plasma S1P. Here, we show that during torpor induced by 5′-AMP, there is a similar reduction in the number of circulating lymphocytes that is a result of their retention in secondary lymphoid organs. This lymphopenia could be mimicked by engagement of A2BRs by a selective A2BR agonist (LUF6210) in the absence of changes in temperature and prevented by A2BR antagonists during 5′-AMP-induced torpor. In addition, forced cooling of mice led to peripheral blood lymphopenia, independent of A2BR signaling. The induction of torpor using 5′-AMP impacted the migration of lymphocytes within and between secondary lymphoid organs. During torpor, the homing into LNs was impaired, and two-photon intravital microscopy revealed that cell motility was decreased significantly and rapidly upon 5′-AMP administration. Furthermore, the S1P plasma concentration was reduced by 5′-AMP but not by LUF6210. S1P plasma levels restored upon arousal. Likely, the reduced migration in LNs combined with the reduced S1P plasma level substantially reduces lymphocyte egress after injection of 5′-AMP. In conclusion, 5′-AMP induces a state of pharmacological torpor in mice, during which, lymphopenia is governed primarily by body temperature-independent suppression of lymphocyte egress from LNs.
Structure and function of plant cell wall polysaccharides
Authors: Darvill Alan G. , Albersheim Peter , McNEIL Michael , Lau James M. , York William S. , Stevenson Thomas T. , Thomas Jerry , Doares Steven , Gollin David J. , Chelf Paulanne , Davis Keith 
Published: May 2013

ABSTRACT
Studies of the primary structures of polysaccharides of growing plant cell walls have shown that these structures are far more complex than was anticipated just a few years ago. This complexity can best be appreciated by considering xyloglucan, a hemicellulose present in the cell wall of both monocots and dicots, and rhamnogalacturonan II (RG-II) and rhamnogalacturonan I (RG-I), two structurally unrelated pectic polysaccharides. This realization led us to postulate that cell wall polysaccharides have functions beyond determining the size, shape and strength of plants. Some years ago we demonstrated that oligosaccharide fragments of a branched β-linked glucan of fungal cell walls can elicit the production of phytoalexins (antibiotics) in plants by inducing the formation of the enzymes responsible for synthesis of the phytoalexins. It has now been ascertained and confirmed by synthesis that the elicitor activity resides in a very specific hepta-jB-n-glucoside. The heptaglucoside has been shown to elicit phytoalexins by activating the expression of specific genes, that is, by causing the synthesis of the mRNAs that encode the enzymes that synthesize phytoalexins. In other words, complex carbohydrates can be regulatory molecules. Further experiments established that oligosaccharide fragments of polysaccharides, produced by acid or base hydrolysis or by enzymolysis of primary cell walls of plants, also evoked defence responses in plants. Subsequently, we learned that defined fragments of polysaccharides, released from covalent attachment within plant cell walls, can function as regulators of various physiological processes such as morphogenesis, rate of cell growth and time of flowering and rooting, in addition to activating mechanisms for resisting potential pathogens. Examples of plant oligosaccharides with regulatory properties (called oligosaccharins) will be described.
New approaches to the study of cellulose biosynthesis
Authors: Delmer D. P. , Cooper G. , Alexander D. , Cooper J. , Hayashi T. , Nitsche C. , Thelen M. 
Published: May 2013

ABSTRACT
Examples of a variety of approaches for studying the mechanism and regulation of cellulose biosynthesis are presented. Attempts to demonstrate conclusively a cellulose synthase activity using membrane preparations derived from higher plants have not been successful; the predominant UDP-glucose: β-glucan-β-glucosyltransferase detected in these preparations is a β (1→3)-glucan synthase that is dependent upon Ca2+ and a β-glucobiose, such as laminaribiose or cellobiose, for activity. Xyloglucan glucosyltransferase activity is detected in all plant preparations examined and, in cotton fibres, the activity of this enzyme correlates well with the level of xyloglucan found in the fibre. Low activity for a Mg2+-dependent β-(l→4)-glucan synthase is found in extracts from soybeans and mung beans, but not cotton fibres; this enzyme could represent either a dissociated form of xyloglucan glucosyltransferase or a partially latent form of cellulose synthase. In vitro translation of RNA from developing cotton fibres shows notable increases in the level of several relatively abundant translatable mRNAs associated with the time of onset of secondary-wall cellulose synthesis. In order to determine whether these apparent changes in gene expression represent enhanced expression of specific genes required for cellulose synthesis, several strategies are being developed for identification of specific polypeptides required for this process. One strategy involves the successful development of a technique for detection of glucan synthase activity in acrylamide gels, a technique that should prove useful for characterization of the polypeptide composition of such enzymes. We have also synthesized a photoaffinity analogue of 2,6-dichlorobenzonitrile (DOB), a potent and specific inhibitor of cellulose synthesis. The analogue is also an effective inhibitor in vivo, and upon ultraviolet irradiation of extracts in the presence of the radioactive analogue, we observe a relatively specific labelling of a polypeptide of 18 × 103Mr. Finally, we have studied the spatial regulation and structural requirements for cellulose synthesis in internode cells of the alga Chara corallina. Cellulose deposition in vivo shows spatial localization, which correlates with acid and base bands along the cell. Using internodes perfused with solutions containing UDP-[14C]glucose and subsequently ligated, we were able to demonstrate synthesis of a highly insoluble cell-wall-localized glucan, thus offering hope that Chara can be developed as another useful system for studying the mechanism and regulation of cellulose synthesis.
The conformation of insulin-like growth factors: relationships with insulins
Authors: Dafgård Eva , Bajaj Mona , Honegger Anne Marie , Pitts Jim , Wood Stephen , Blundell Tom 
Published: May 2013

ABSTRACT
The insulin-like growth factors and hystricomorph insulins have been modelled by interactive computer graphics on the assumption that their sequence homology to insulin implies that they will have a similar tertiary structure. These studies suggest that, although the insulin-related molecules can adopt the insulin fold, they are unlikely to form hexamers and if they form dimers they will be of reduced stability. The non-suppressibility of insulin-like growth factors by anti-insulin antibodies is explained in terms of differences of surface residues in the region A8-A10 and B1-B5. Receptor affinity of insulins and insulin-like growth factors for insulin receptors is explicable in terms of a receptor-binding site in the vicinity of B25 Phe on the insulin surface. An equivalent region around B25 Tyr of insulin-like growth factors may be responsible for their binding to type 1 receptors, although binding type 2 receptors must involve a different surface region not shared by insulin.
The role of stromal cells and growth factors in haemopoiesis and modulation of their effects by the src oncogene
Authors: Dexter T. M. , Whetton A. D. , Spooncer E. , Heyworth C. , Simmons P. 
Published: May 2013

ABSTRACT
In the haemopoietic system the mature blood cells have only a finite lifetime. For example, a circulating granulocyte in the peripheral blood has an approximate half-life of 7h (Cartwright, Athens & Wintrobe, 1964; Dancey, Dubelbeiss, Harker & Finch, 1976) whilst the lifetime of an erythrocyte is approximately 120 days (Wickramasinghe & Weatherall, 1982). This constant ‘death’ of mature functional haemopoietic cells means that new blood cells must replace those that are removed. The process of haemopoiesis provides the mature functional blood cells to replace those lost as a consequence of performing their biological functions (e.g. lymphocytes and macrophages in the immune response) or through apparent old age and breakdown (e.g. erythrocytes that are 110-120 days old). The major questions that we are required to answer about this process are ‘where do all these new cells come from?’, ‘what regulates their production?’ and ‘how is this mechanism of control lost in haemopoietic disorders such as leukaemia, hyperproliferative diseases and anaemias?’. Recent work in the field of haemopoiesis has given some clues to the answers to the questions, which provide an intriguing insight into not only haemopoiesis itself but the possible lesions associated with the various blood disorders.
Growth Polarity And Cytokinesis In Fission Yeast: The Role Of The Cytoskeleton
Authors: Marks John , M. Hagan Iain , S. Hyams Jeremy 
Published: May 2013

ABSTRACT
The distribution of F-actin in the fission yeast Schizosaccharomyces pombe was investigated by fluorescence microscopy using rhodamine-conjugated phalloidin. Fluorescence was seen either at the ends of the cell or at the cell equator. End staining was predominantly in the form of dots whilst equatorial actin was resolved as a filamentous band. The different staining patterns showed a close correlation with the known pattern of cell wall deposition through the cell cycle. In small, newly divided cells actin was localized at the single growing cell end whilst initiation of bipolar cell growth was coincident with the appearance of actin at both ends of the cell. As cells ceased to grow and entered cell division, a ring of actin was seen to anticipate the deposition of the septum at cytokinesis. The relationship between actin and cell wall deposition was further confirmed in three temperature-sensitive cell division cycle (cdc) mutants; cdc 10, cdc 11 and cdc 13. Immunofluorescence microscopy of S. pombe with an anti-tubulin antibody revealed a system of cytoplasmic microtubules extending between the cell ends. The function of these was investigated in the coldsensitive, benomyl-resistant mutant benL In cold-grown cells actin was seen to form conspicuous filamentous rings around the nucleus. The origin of these and the possible role of microtubules in the cell-cycle-dependent rearrangements of F-actin are discussed.
Morphogenesis And The Control Of Microtubule Dynamics In Cells
Authors: Kirschner Marc , Schulze Eric 
Published: May 2013

ABSTRACT
Microtubules show unusual dynamic properties at steady state in vitro. While overall the polymer mass remains stable, individual polymers in the population are either growing or shrinking. This phenomenon called dynamic instability is best explained by the known coupling of polymerization to GTP hydrolysis, and the hypothesis that the stability or instability of the whole polymer is determined by whether GTP or GDP is bound to the terminal subunit. Similar unusual dynamics have now also been found in vivo. By visualizing new subunit assembly after injection of tubulin modified with biotin into living fibroblast cells, we can visualize new growth on individual microtubules with antibody to biotin. Microtubules grow in vivo at about 4 µm min-’ and after rapid and precessive depolymerization old microtubules are replaced by new growth from the centrosome. Some microtubules turn over much more slowly and these stable microtubules have a different spatial distribution from the majority of dynamic ones. The existence of both stable and dynamic microtubules in the same cell suggests a model for morphogenesis of the microtubule cytoskeleton. The rapid turnover of microtubules in the cell provides a complex population upon which selective factors can act. Stability can be generated at the end of the polymer and affects the entire microtubule. This model of selective stabilization at the microtubule ends is discussed in terms of recent experiments on the establishment of kinetochore-pole microtubules during mitosis.
Molecular evolution of viruses; ‘trees’, ‘clocks’ and ‘modules’
Authors: Gibbs Adrian 
Published: May 2013

ABSTRACT
Comparisons of the nucleotide sequences of viral genomes, and derived amino acid sequences, mostly confirm the traditional taxonomic groupings of viruses. These comparisons have also shown unexpected homologies between genes of viruses from different groups previously thought to be unrelated, and between some viral and non-viral genes. Comparisons of the three-dimensional structures of the particle proteins of some viruses have also revealed unexpected relationships, and, together with the sequence homologies, suggest that some ancestral viruses had ‘modular’ origins.
Some of the sequence differences have been used to construct phylogenies. However, there is evidence that viral gene ‘molecular clocks’ do not always keep time consistently over very long or very short evolutionary time periods. Clues on evolution mostly come from comparative studies of living or fossil organisms. Fossils of viruses are not known, and thus clues of the origins and evolution of viruses are obtained by comparing extant forms. For example, by comparing isolates of different viruses, or strains of viruses, one can infer the properties of their ancestors, and by comparing isolates obtained during an epidemic, and sequentially related to one another, one can observe directly the type and timing of evolutionary changes.
The TATA-binding protein is a general transcription factor for RNA polymerase III
Authors: White Robert J. , Rigby Peter W. J. , Jackson Stephen P. 
Published: May 2013

ABSTRACT
The TATA-binding protein (TBP) is a principal component of the general factor TFIID and is required for specific transcription by RNA polymerase II. We have shown that TBP is also a general factor for RNA poly-merase III.
Multiple effects on liver-specific gene expression in albino lethal mice caused by deficiency of an enzyme in tyrosine metabolism
Authors: Kelsey Gavin , Ruppert Siegfried , Schedl Andreas , Schmid Erika , Thies Edda , Schütz Günther 
Published: May 2013

ABSTRACT
alf/hsdr-1 is a locus in the mouse defined by albino deletions to be essential for neonatal viability. Homozygous deletion of alf/hsdr-1 leads to a pleiotropic phenotype in liver and kidney, including impaired perinatal activation of hormone-dependent genes, and the induction of detoxifying enzymes and early-response genes. To elucidate the molecular basis of this complex phenotype, we have identified the gene mapping at alf/hsdr-1 by positional cloning, using overlapping albino locus deletions to define the location of alf/hsdr-1. The gene encodes fumarylacetoacetate hydrolase, F AH, an enzyme of tyrosine metabolism. Genetically determined FAH deficiency in man leads to a severe liver failure in infants. In mice, we find that the normal sites of expression of FAH correlate tightly with cell-types which display abnormalities in albino lethal mice. The identification of the Fah gene as a candidate for alf/hsdr-1 offers a novel explanation for the complex phenotype, one into which all aspects can be accommodated. The phenotype can now be understood as a sequence of responses to toxic electrophilic metabolites.
Targets of homeotic gene regulation in Drosophila
Authors: White R. A. H. , Brookman J. J. , Gould A. P. , Meadows L. A. , Shashidhara L. S. , Strutt D. I. , Weaver T. A. 
Published: May 2013

ABSTRACT
We have used a chromatin immunopurification approach to identify target genes regulated by the homeotic gene Ultrabithorax. A monoclonal antibody against the Ultrabithorax gene product is used to immunopurify in vivo Ultrabithorax protein binding sites in embryonic chromatin. The procedure gives an enrichment of sequences with matches to a consensus homeodomain binding site. In one case we have shown that an immunopurifled sequence lies within a 4 kb fragment that acts in vivo as a homeotic response element. We anticipate that this approach will enable us to identify further targets, allowing the analysis of their regulation and function. The chromatin immunopurification strategy may be of general application for the identification of direct in vivo targets of DNA-binding proteins.
The regulation of euchromatin and heterochromatin by histones in yeast
Authors: Grunstein M. , Hecht A. , Fisher-Adams G. , Wan J. , Mann R. K. , Strahl-Bolsinger S. , Laroche T. , Gasser S. 
Published: May 2013

ABSTRACT
Yeast chromosomes may lack the linker histone Hl (normally required to compact 10 nm beads-on-a-string fiber into the 30 nm fiber) and there is no cytological evidence for higher order fiber structure but they do contain regions which correspond to euchromatin and heterochromatin of higher eukaryotes. Both euchromatin and heterochromatin contain nucleosomal particles (composed of two molecules each of histones H2A, H2B, H3 and H4), however histones have been shown to regulate genes in these regions in quite different ways. The mechanisms by which such regulation occurs are the topic of this paper.
Synthesis and Molecular Shuttling of [2]Rotaxanes under Mild Conditions
Authors: Tukada Hideyuki , Hiraki Toshihiro , Nakamura Hiroshi 
Published: May 2013

Abstract
[2]Rotaxanes constructed with an ethereal end-capped axle and a dibenzo-24-crown-8 wheel were synthesized from pseudorotaxanes bearing an alcoholic terminus and diaryldiazomethanes using diphenyl phosphate as a catalyst. The reaction proceeded at room temperature in nonpolar solvents within several hours. The [2]rotaxanes thus obtained behaved as ammonium salts derived from a very strong base such as DBU. Thus, the amine form of the [2]rotaxane reacted with a weak acid, CO2–H2O, to give a hydrogencarbonate salt of the [2]rotaxane, which turned back to the amine form after drying followed by evacuation.
Molecular Design of High-molecular-orientation Electron-transport Materials and Application to Organic Light-emitting Diodes
Authors: Togashi Kazunori , Sagara Yuta , Yasuda Takuma , Adachi Chihaya 
Published: May 2013

Abstract
Two novel electron-transport materials (ETMs), 2,3′-Bpy-TP and 2,4′-Bpy-TP, with high horizontal molecular orientation to substrates, were synthesized. It was shown by measuring the IR absorption spectra of their deposited thin films that C–H···N hydrogen bonds are formed between the 2,3′-Bpy-TP molecules and between the 2,4′-Bpy-TP molecules. It was also shown that there is a closed relationship between their molecular orientations and the driving voltages of electron-only devices (EODs) using them as electron-transport layers (ETLs).
Crystal structure of bis(2-(3-(carboxylatomethyl-κO,O')-4-(phenylthio)- phenyl)propanoate-κO,O')bis(2,2'-dipyridyl-κN,N')dizinc(II), C54H44N4O8S2Zn2
Authors: Shi Zhan-Wang , Liang Peng , Cen Cui-Ling , Zhao Rong-Ping , Wei Xi , Guan Nian 
Published: May 2013

Abstract C54H44N4O8S2Zn2, monoclinic, P21/c (no. 14), a = 13.299(4) Å, b = 12.019(3) Å, c = 15.320(4) Å, β = 93.256(4)°, V = 2444.8 Å3, Z = 2, Rgt(F) = 0.0502, wRref(F2) = 0.1430, T = 296 K.
Crystal structure of bis(nitrito-κN)bis(3-phenylpyridine-κN) palladium(II), C22H18N4O4Pd
Authors: Ha Kwang 
Published: May 2013

Abstract C22H18N4O4Pd, monoclinic, P21/c (no. 14), a = 7.474(1) Å, b = 13.496(2) Å, c = 10.587(2) Å, β = 108.549(4)°, V = 1012.5 Å3, Z = 2, Rgt(F) = 0.0403, wRref(F2) = 0.0794, T = 200 K.
The microstructural and optical properties of Ge/Si heterostructures grown by low-temperature molecular beam epitaxy
Authors: Roddatis Vladimir V. , Yakunin Sergey N. , Vasiliev Alexander L. , Kovalchuk Mikhail V. , Seregin Alexej Yu , Burbaev Timur M. , Gordeev Michail N. 
Published: May 2013

Abstract
Surface Characterization of Clean Gd5Ge4(010)
Authors: Yuen Chad D. , Miller Gordon J. , Thiel Patricia A. 
Published: May 2013

AbstractBased on X-ray photoelectron spectroscopy, Gd5Ge4(010) does not show evidence of surface segregation. Scanning tunneling microscopy reveals two types of terraces which alternate laterally on the surface. From the step heights, these two surface terminations are assigned as dense, Gd-pure layers in the bulk structure. There is evidence of reconstruction on one type of terrace.
SEMICONDUCTOR BEHAVIOR OF 2, 5-AROMATIC DISUBSTITUTED PYROLLES, AN EXPERIMENTAL AND THEORETICAL STUDY
Authors: Fomina L. , Valdivieso C. Y. León , Galán G. Zaragoza , Bizarro M. , Zaragoza I. P. , Sánchez J. Godínez , Salcedo R. , Baeza A. 
Published: May 2013

ABSTRACTTheoretical calculations were performed on 2, 5-aromatic substituted pyrroles which have a nitro-benzene or a cyano-benzene link to the nitrogen atom of the pyrrol fragment. The molecules manifested interesting semiconductor behavior that was confirmed when thin films were prepared and their corresponding electrical characterization undertaken. The reason for this behavior is discussed, with reference to the electron withdrawing feature of the substituents in the benzene chain.
Reversible Light-Induced On-Off Switching of Charge Traps in Quantum Dots Probe by Variable-Pulse-Rate Photoluminescence Spectroscopy.
Authors: Aresti Mauro , Marceddu Marco , Saba Michele , Quochi Francesco , Huang Jing , Talapin Dmitri V. , Mura Andrea , Bongiovanni Giovanni 
Published: May 2013

ABSTRACTWe devise an experiment, variable pulse rate photoluminescence, to control the accumulation of charges and the activation of charge traps in colloidal nanocrystals. The dynamics of these states is studied, with pulse repetition frequencies ranging from a few hundred hertz to the megahertz regime, by monitoring photoluminescence spectrograms with picosecond temporal resolution. We find that both photocharging and charge trapping contribute to photoluminescence quenching, and both processes can be reversibly induced by light.