bluuebunny/crossref_metadata_2025_split huggingface dataset:
A UspA2H-Negative Variant of
Moraxella catarrhalis
Strain O46E Has a Deletion in a Homopolymeric Nucleotide Repeat Common to
uspA2H
Genes
Authors: Wang Wei , Pearson Melanie M. , Attia Ahmed S. , Blick Robert J. , Hansen Eric J. 
Published: January 2007

ABSTRACT

Moraxella catarrhalis
strains can express either a UspA2 protein or a UspA2H protein. The latter protein is encoded by a gene that possesses a homopolymeric nucleotide tract containing eight adenine (A) residues [i.e., a poly(A) tract] which is located near the 5′ end. A spontaneous UspA2H-negative variant of
M. catarrhalis
strain O46E, designated O46E.U2V, was found to have a
uspA2H
poly(A) tract that contained seven A residues. Northern blot analysis of total RNA from the O46E parent strain revealed a readily detectable
uspA2H
mRNA transcript, whereas little or no
uspA2H
transcript was detectable in total RNA from the UspA2H-negative variant O46E.U2V. The 5′ end of the
uspA2H
genes from both the O46E parent strain and the O46E.U2V variant were ligated to a promoterless
lacZ
gene to prepare translational fusions for use as reporter constructs. The level of β-galactosidase activity expressed by the fusion construct containing eight A residues in its poly(A) tract was 200-fold greater than that obtained with the construct that had seven A residues. Site-directed mutagenesis of the 5′ end of the
uspA2H
gene confirmed that translation was initiated at a GTG codon located 21 nucleotides (nt) upstream of the poly(A) tract. Primer extension analysis determined that the transcriptional start site of the
uspA2H
gene was located 291 nt upstream from the GTG translational start codon. This poly(A) tract was also found to be present in the
uspA2H
genes of other
M. catarrhalis
strains.
Surfactant Protein A2 (SP-A2) Variants Expressed in CHO Cells Stimulate Phagocytosis of
Pseudomonas aeruginosa
More than Do SP-A1 Variants
Authors: Mikerov Anatoly N. , Wang Guirong , Umstead Todd M. , Zacharatos Mario , Thomas Neal J. , Phelps David S. , Floros Joanna 
Published: January 2007

ABSTRACT

Surfactant protein A (SP-A) enhances phagocytosis of
Pseudomonas aeruginosa
. Two functional genes,
SP-A1
and
SP-A2
, encode human SP-A. As we showed before, baculovirus-mediated insect cell-expressed SP-A2 enhances the association of
P. aeruginosa
with rat alveolar macrophages (rAMs) more than does SP-A1. However, true phagocytosis (internalization) was not shown, and insect cell derived proteins lack or are defective in certain mammalian posttranslational modifications that may be important for SP-A1 and SP-A2 activity and specificity. Here we used SP-A1 (6A
2
, 6A
4
) and SP-A2 (1A
0
, 1A
1
) allele variants expressed by CHO (Chinese hamster ovary) mammalian cells to study their effect on association and/or internalization of
P. aeruginosa
by rAMs and/or human AMs (hAMs) and to study if phagocytosis can be modulated differentially and/or more effectively by CHO cell-expressed SP-A variants than by insect-cell expressed SP-A variants. For cell association and internalization assessments, light microscopy and fluorescence-activated cell sorter analyses were used, respectively. We found the following for the first time. (i) SP-A2 variants enhanced phagocytosis (cell association and/or internalization) of
P. aeruginosa
more than SP-A1 variants did, and the cell association correlated with internalization. (ii) Differences in the activities of SP-A variants were observed in the following order: 1A
1
>1A
0
>6A
2
>6A
4
. (iii) rAMs, although more active than hAMs, are an appropriate model, as SP-A2 variants exhibited activity higher than that seen for SP-A1 variants with either rAMs or hAMs. (iv) CHO cell-expressed SP-A was considerably more active than insect cell-expressed variants. We conclude that SP-A2 variants stimulate phagocytosis of
P. aeruginosa
more effectively than SP-A1 variants and that posttranslational modifications positively influence the phagocytic activity of SP-A.
Phagocytosis ofBorrelia burgdorferiandTreponema pallidumPotentiates Innate Immune Activation and Induces Gamma Interferon Production
Authors: Moore Meagan W. , Cruz Adriana R. , LaVake Carson J. , Marzo Amanda L. , Eggers Christian H. , Salazar Juan C. , Radolf Justin D. 
Published: January 2007

ABSTRACTWe examined the interactions of live and lysed spirochetes with innate immune cells. THP-1 monocytoid cells were activated to comparable extents by liveBorrelia burgdorferiand byB. burgdorferiandTreponema pallidumlysates but were poorly activated by liveT. pallidum. Because THP-1 cells poorly internalized live spirochetes, we turned to an ex vivo peripheral blood mononuclear cell system that would more closely reflect spirochete-mononuclear phagocyte interactions that occur during actual infection. In this system,B. burgdorferiinduced significantly greater monocyte activation and inflammatory cytokine production than did borrelial lysates orT. pallidum, and onlyB. burgdorferielicited gamma interferon (IFN-γ) from NK cells.B. burgdorferiwas phagocytosed avidly by monocytes, whileT. pallidumwas not, suggesting that the enhanced response to liveB. burgdorferiwas due to phagocytosis of the organism. When cytochalasin D was used to block phagocytosis of liveB. burgdorferi, cytokine production decreased to levels comparable to those induced byB. burgdorferilysates, while the IFN-γ response was abrogated altogether. In the presence of human syphilitic serum,T. pallidumwas efficiently internalized and initiated responses resembling those observed with liveB. burgdorferi, including the production of IFN-γ by NK cells. Depletion of monocytes revealed that they were the primary source of inflammatory cytokines, while dendritic cells (DCs) directed IFN-γ production from innate lymphocytes. Thus, phagocytosis of live spirochetes initiates cell activation programs in monocytes and DCs that differ qualitatively and quantitatively from those induced at the cell surface by lipoprotein-enriched lysates. The greater stimulatory capacity ofB. burgdorferiversusT. pallidumappears to be explained by the successful recognition and phagocytosis ofB. burgdorferiby host cells and the ability ofT. pallidumto avoid detection and uptake by virtue of its denuded outer membrane rather than by differences in surface lipoprotein expression.
Role of Unsaturated Fatty Acid Biosynthesis in Virulence of
Streptococcus mutans
Authors: Fozo Elizabeth M. , Scott-Anne Kathy , Koo Hyun , Quivey Robert G. 
Published: January 2007

ABSTRACT

An insertionally inactivated
fabM
strain of
Streptococcus mutans
does not produce unsaturated membrane fatty acids and is acid sensitive (E. M. Fozo and R. G. Quivey, Jr., J. Bacteriol. 186:4152-4158, 2004). In this study, the strain was shown to be poorly transmissible from host to host. Animals directly infected with the
fabM
strain exhibited fewer and less severe carious lesions than those observed in the wild-type strain.
FNR Is a Global Regulator of Virulence and Anaerobic Metabolism inSalmonella entericaSerovar Typhimurium (ATCC 14028s)
Authors: Fink Ryan C. , Evans Matthew R. , Porwollik Steffen , Vazquez-Torres Andres , Jones-Carson Jessica , Troxell Bryan , Libby Stephen J. , McClelland Michael , Hassan Hosni M. 
Published: January 2007

ABSTRACTSalmonella entericaserovar Typhimurium must successfully transition the broad fluctuations in oxygen concentrations encountered in the host. InEscherichia coli, FNR is one of the main regulatory proteins involved in O2sensing. To assess the role of FNR in serovar Typhimurium, we constructed an isogenicfnrmutant in the virulent wild-type strain (ATCC 14028s) and compared their transcriptional profiles and pathogenicities in mice. Here, we report that, under anaerobic conditions, 311 genes (6.80% of the genome) are regulated directly or indirectly by FNR; of these, 87 genes (28%) are poorly characterized. Regulation by FNR in serovar Typhimurium is similar to, but distinct from, that inE. coli.Thus, genes/operons involved in aerobic metabolism, NO· detoxification, flagellar biosynthesis, motility, chemotaxis, and anaerobic carbon utilization are regulated by FNR in a fashion similar to that inE. coli. However, genes/operons existing inE. colibut regulated by FNR only in serovar Typhimurium include those coding for ethanolamine utilization, a universal stress protein, a ferritin-like protein, and a phosphotransacetylase. Interestingly,Salmonella-specific genes/operons regulated by FNR include numerous virulence genes withinSalmonellapathogenicity island 1 (SPI-1), newly identified flagellar genes (mcpAC,cheV), and the virulence operon (srfABC). Furthermore, the role of FNR as a positive regulator of motility, flagellar biosynthesis, and pathogenesis was confirmed by showing that the mutant is nonmotile, lacks flagella, is attenuated in mice, and does not survive inside macrophages. The inability of the mutant to survive inside macrophages is likely due to its sensitivity to the reactive oxygen species generated by NADPH phagocyte oxidase.
Ligand-Controlled Proteolysis of theEscherichia coliTranscriptional Regulator ZntR
Authors: Pruteanu Mihaela , Neher Saskia B. , Baker Tania A. 
Published: January 2007

ABSTRACTProteases play a crucial role in remodeling the bacterial proteome in response to changes in cellular environment.Escherichia coliZntR, a zinc-responsive transcriptional regulator, was identified by proteomic experiments as a likely ClpXP substrate, suggesting that protein turnover may play a role in regulation of zinc homeostasis. When intracellular zinc levels are high, ZntR activates expression of ZntA, an ATPase essential for zinc export. We find that ZntR is degraded in vivo in a manner dependent on both the ClpXP and Lon proteases. However, ZntR degradation decreases in the presence of high zinc concentrations, the level of ZntR rises, and transcription of thezntAexporter is increased. Mutagenesis experiments reveal that zinc binding does not appear to be solely responsible for the zinc-induced protection from proteolysis. Therefore, we tested whether DNA binding was important in the zinc-induced stabilization of ZntR by mutagenesis of the DNA binding helices. Replacement of a conserved arginine (R19A) in the DNA binding domain both enhances ZntR degradation and abolishes zinc-induced transcriptional activation ofzntA. Biochemical and physical analysis of ZntRR19Ademonstrates that it is structurally similar to, and binds zinc as well as does, the wild-type protein but is severely defective in binding DNA. Thus, we conclude that two different ligands—zinc and DNA—function together to increase ZntR stability and that ligand-controlled proteolysis of ZntR plays an important role in fine-tuning zinc homeostasis in bacteria.
Enhancement of the Synthesis of RpoN, Cra, and H-NS by Polyamines at the Level of Translation in
Escherichia coli
Cultured with Glucose and Glutamate
Authors: Terui Yusuke , Higashi Kyohei , Taniguchi Shiho , Shigemasa Ai , Nishimura Kazuhiro , Yamamoto Kaneyoshi , Kashiwagi Keiko , Ishihama Akira , Igarashi Kazuei 
Published: January 2007

ABSTRACT

Proteins whose synthesis is enhanced by polyamines at the level of translation were identified in a polyamine-requiring mutant cultured in the presence of 0.1% glucose and 0.02% glutamate instead of 0.4% glucose as an energy source. Under these conditions, enhancement of cell growth by polyamines was almost the same as that in the presence of 0.4% glucose. It was found that synthesis of RpoN, Cra, and H-NS was enhanced by polyamines at the level of translation at the early logarithmic phase of growth (
A
540
of 0.15). The effects of polyamines on synthesis of RpoN, H-NS, and Cra were due to the existence of unusual Shine-Dalgarno sequences (RpoN and H-NS) and an inefficient GUG initiation codon (Cra) in their mRNAs. Thus,
rpoN
,
cra
, and
hns
genes were identified as new members of the polyamine modulon. Because most of the polyamine modulon genes thus far identified encode transcription factors (RpoS [σ
38
], Cya, FecI [σ
18
], Fis, RpoN [σ
54
], Cra, and H-NS), DNA microarray analysis of mRNA expressed in cells was performed. At the early logarithmic phase of growth, a total of 97 species of mRNAs that were up-regulated by polyamines more than twofold were under the control of seven polyamine modulon genes mentioned above.
The Sugar Phosphotransferase System of
Vibrio fischeri
Inhibits both Motility and Bioluminescence
Authors: Visick Karen L. , O'Shea Therese M. , Klein Adam H. , Geszvain Kati , Wolfe Alan J. 
Published: January 2007

ABSTRACT

Magnesium-dependent induction of
Vibrio fischeri
flagellar (Mif) biogenesis depends upon two diguanylate cyclases, suggesting an inhibitory role for cyclic di-GMP. Here, we report that cells defective for the sugar phosphotransferase system (PTS) exhibited a magnesium-independent phenotype similar to that of mutants of the Mif pathway. Unlike Mif mutants, PTS mutants also were hyperbioluminescent.
The Orphan Response Regulator HP1021 of
Helicobacter pylori
Regulates Transcription of a Gene Cluster Presumably Involved in Acetone Metabolism
Authors: Pflock Michael , Bathon Melanie , Schär Jennifer , Müller Stefanie , Mollenkopf Hans , Meyer Thomas F. , Beier Dagmar 
Published: January 2007

ABSTRACT

Helicobacter pylori
is a gastric pathogen for which no nonhuman reservoir is known. In accordance with the tight adaptation to its unique habitat, the human stomach,
H. pylori
is endowed with a very restricted repertoire of regulatory proteins. Nevertheless, the three complete two-component systems of
H. pylori
were shown to be involved in the regulation of important virulence traits like motility and acid resistance and in the control of metal homeostasis. HP1021 is an orphan response regulator with an atypical receiver domain whose inactivation has a considerable impact on the growth of
H. pylori
. Here we report the identification of HP1021-regulated genes by whole-genome transcriptional profiling. We show that the transcription of the essential housekeeping genes
nifS
and
nifU
, which are required for the assembly of Fe-S clusters, is activated by HP1021. Furthermore, we demonstrate that the expression of a gene cluster comprising open reading frames hp0690 to hp0693 and hp0695 to hp0697 which is probably involved in acetone metabolism is strongly upregulated by HP1021. Evidence is provided for a direct regulation of the hp0695-to-hp0697 operon by the binding of HP1021 to its promoter region.
Cover Picture: Nanoscale Deposition of Single‐Molecule Magnets onto SiO2 Patterns (Adv. Mater. 2/2007)
Authors: Martínez R. V. , García F. , García R. , Coronado E. , Forment‐Aliaga A. , Romero F. M. , Tatay S. 
Published: January 2007

AbstractThe cover shows a schematic of scanning probe nanolithography based on the spatial confinement of an oxidation reaction within a water meniscus, and its application for fabricating ordered arrays of cationic Mn12 single‐molecule magnets. Romero, Coronado, Garcìa, and co‐workers report on p. 291 that electrostatic interactions between the molecules and trapped charges within the nanodots drive the positioning of the molecules at the nanoscale.
Prediction of volumetric productivity of an outdoor photobioreactor
Authors: Bosma Rouke , van Zessen Erik , Reith Johannes H. , Tramper Johannes , Wijffels René H. 
Published: January 2007

AbstractVolumetric productivity of Monodus subterraneus cultivated in an outdoor pilot‐plant bubble column was predicted with a mathematical model. Two border cases to model the photobioreactor were chosen. Firstly, a model with no light integration in which it is assumed that microalgae can adapt immediately to local light conditions. Secondly, full light integration implicating that microalga can convert all absorbed light with a photosynthetic yield based on average light intensity. Because temperature and light conditions in our photobioreactor changed during the day, photosynthetic yields at any combination of temperature and light intensity were needed. These were determined in repeated‐batch lab‐scale experiments with an experimental design. The model was evaluated in an outdoor bubble column at different natural light conditions and different temperatures. Volumetric productivities in the bubble column were predicted and compared with experimental volumetric productivities. The light integration model over‐estimated productivity, while the model in which we assumed no light integration under‐estimated productivity. Light integration occurred partly (47%) during the period investigated. The average observed biomass yield on light was 0.60 g·mol−1. The model of partly light integration predicted an average biomass yield on light of 0.57 g·mol−1 and predicted that productivity could have been increased by 19% if culture temperature would have been maintained at 24°C. Biotechnol. Bioeng. 2007; 97: 1108–1120. © 2007 Wiley Periodicals, Inc.
Influence of Substrate Surface Polarity on Epitaxial Layer Growth of CuInSe2 on GaAs
Authors: Schumann B. , Neumann H. , Nowak E. , Kühn G. 
Published: January 2007

AbstractCuInSe2 thin films with thicknesses of about 0.1 μm were deposited onto (III) B‐oriented GaAs substrates by flash evaporation. At substrate temperatures Tsub = 695–820 K the films have the chalcopprite structure with some admixture of the cubic sphalerite phase. At Tsub > 820 K only the sphalerite phase was found All the films are partly polycrystalline. From the electrical properties it follows that the films are characterized by nearly complete compensation at Tsub = 695–820 K. At Tsub = 870 K the films are p‐type conducting and show two acceptor states with ionization energies of about 8 meV and 105 meV.
Experimental Determination and Thermodynamic Calcultions of the Relationship between Vapour Phase Composition and Mixed Crystal Composition in the Ga‐HCI‐PH3‐AsH3‐(NH3)‐H2 System
Authors: Jacobs K. , Peuschel G.‐P. , Peuschel R. , Probst R. , Butter E. , Bugge F. 
Published: January 2007

AbstractThe relationship between the composition of GaAs1–xPx layers and the composition of the vapour phase has been investigated experimentally and theoretically. Using KIRWAN'Sequilibrium constants excellent agreement between calculated and experimental data is obtained over the whole composition range. Different models and parameters for the calculation of the soild solution activity coefficients result in only small differences for the calculated alloy composition so that no decision can be made from the experiments for one model to be preferred. Increasing addition of NH3 to the vapour phase up to concentrations exceeding those of the crystal forming gases by an order of magnitude has no influence on the alloy composition, although the nitrogen concentration in the layers increases as deduced from the shift of the wavelength of the maximum photoluminescence intensity.
On the Preparation of ZnO Single Crystals
Authors: Fischer K. , Sinn E. 
Published: January 2007

AbstractZnO single crystals were prepared by means of two methods:i slow cooling of ZnO/PbF2 (PbO) high temperature solution, (ii) flux reaction technique, hydrolysis of ZnF2 in PbF2 as a solvent. At cooling rate ≥ 0.9 K/h the known plates, hexagonal prisms, and hollow crystals were obtained. At the cooling rate 0.6 K/h compact crystals have grown. This habit was also formed with the flux reaction technique. An estimation of the deposition rates of both methods has shown approximative agreement between the cooling runs with 0.6 K/h and the flux reaction technique under the chosen conditions. The deposition rate appears to be a relevant parameter for forming compact ZnO crystals in these systems.
An Improved Method for Purification of β‐Copperphthalocyanine
Authors: Mizuguchi Jin 
Published: January 2007

AbstractA sublimation apparatus in which a high temperature slightly lower than the sublimation point of copperphthalocyanine remains constant over a long condensation region has been developed. A sufficiently pure material for electrophotographic measurements can be obtained only when this high temperature is maintained nearly constant over the long condensation region along the sublimation tube. After the thired sublimation, the value of copper contents in the sample is 11.03 · 0.02%, according to the chelatometric titrations, while the theoreitcal value of stoichimetric composition is 11.03%. Emission spectrochemical analysis shows that only traces of Si and Mg are found in the sample after the sixth sublimation. Single crystal srown in the sublimation tube are characterized and the growth mechanism is discussed.
Microstructures of Tin Iodide Single Crystals Grown in Silica Gels
Authors: Desai C. C. , Rai J. L. 
Published: January 2007

AbstractSingle crystals of tin iodide (SnI2) have been grown in silica gels. A detailed microtopographical study of {100} faces have been described. Horizontal striations are predominant on these faces for most of the crystals, while few of them show vertical striations. The horizontal striations are associated with the two‐dimensional nucleation theory whereas the vertical striations relate to the growth fronts. Growth layers modified by the presence of misaligned microcystals have been illustrated. The natural etch pits on {100} faces of the crystal are attributed to the dissolution of crystals in the acid set gel. In the light of these observations, the mechanism of the development and growth of these faces have been assessed and the implications are discussed.
Diamond Synthesis in Cool Plasma
Authors: Mania R. , Stobierski L. , Pampuch R. 
Published: January 2007

AbstractThe conditions of low pressure autoepitaxy of diamond are analysed and theoretical concepts concerning the plasmochemical method of diamond synthesis put forward. The experimental method used is described. The obtained results have demonstrated the utility of the plasmochemical method for obtainment of diamond and confirmed the validity of the presented theoretical concepts.
Kinetics of Scale Growth from Quiescent Solutions of Soluble Substances
Authors: Veverka F. , Söhnel O. 
Published: January 2007

AbstractThe kinetics of scale growth on a cooling surface from quiescent aqueous solutions of oxalic acid, Na2HPO4 × 12 H2O, KNO3, Na2SO4 × 10 H2O, and Na3PO4 × 12 H2O saturated at 65, 32, 48.2, 31, and 39.2 °C, resp., was studied. The incurstations formed during 2 min of growth consist of loosely packed dendrites or needle‐like crystals (the former 3 substances), or of tightly packed crystals forming a scale with a “smooth surface” (the latter 2 salts). The kinetic order of growth, g, assessed on the basis of experimental data was smaller than unity in all the studied cases; the g values of smooth incrustations were higher than those of the dendritic ones. It follows from the considerations concerning the possible mechanism of scale growth that the growth is controlled by a mononuculear mechanism. The experimental values of g compare reasonably well with the expected theoretical values.
Temperature and Intensity Behaviour of the pAl0.7Ga0.3As‐pGaAs‐nGaAs Concentrator Solar Cell
Authors: Díaz P. , Hernandez L. , Romero R. 
Published: January 2007

AbstractA semiempirical approch for calculation of pAl0.7Ga0.3As‐pGaAs‐nGaAs concentrator solar cell behaviour in a very wide range of operating temperatures (77 K – 490 K) is developed. Experimental values of cell collection efficiency, short circuit current and open circuit voltage are given, while cell fill factor and overall conversion efficiency are calculated. Optimum cell operating conditions are found both for AM 1 and AM 0 radiation.