bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of starch and amylase on the expression of amylase‐binding protein A in Streptococcus gordonii
Authors: Nikitkova A.E. , Haase E.M. , Scannapieco F.A. 
Published: March 2012

SummaryStreptococcus gordonii is a common oral commensal bacterial species in tooth biofilm (dental plaque) and specifically binds to salivary amylase through the surface exposed amylase‐binding protein A (AbpA). When S. gordonii cells are pretreated with amylase, amylase bound to AbpA facilitates growth with starch as a primary nutrition source. The goal of this study was to explore possible regulatory effects of starch, starch metabolites and amylase on the expression of S. gordonii AbpA. An amylase ligand‐binding assay was used to assess the expression of AbpA in culture supernatants and on bacterial cells from S. gordonii grown in defined medium supplemented with 1% starch, 0.5 mg ml−1 amylase, with starch and amylase together, or with various linear malto‐oligosaccharides. Transcription of abpA was determined by reverse transcription quantitative polymerase chain reaction. AbpA was not detectable in culture supernatants containing either starch alone or amylase alone. In contrast, the amount of AbpA was notably increased when starch and amylase were both present in the medium. The expression of abpA was significantly increased (P < 0.05) following 40 min of incubation in defined medium supplemented with starch and amylase. Similar results were obtained in the presence of maltose and other short‐chain malto‐oligosacchrides. These results suggest that the products of starch hydrolysis produced from the action of salivary α‐amylase, particularly maltose and maltotriose, up‐regulate AbpA expression in S. gordonii.
A Bilayer-Couple Model of Bacterial Outer Membrane Vesicle Biogenesis
Authors: Schertzer Jeffrey W. , Whiteley Marvin 
Published: March 2012

ABSTRACT

Gram-negative bacteria naturally produce outer membrane vesicles (OMVs) that arise through bulging and pinching off of the outer membrane. OMVs have several biological functions for bacteria, most notably as trafficking vehicles for toxins, antimicrobials, and signaling molecules. While their biological roles are now appreciated, the mechanism of OMV formation has not been fully elucidated. We recently demonstrated that the signaling molecule 2-heptyl-3-hydroxy-4-quinolone (PQS) is required for OMV biogenesis in
P. aeruginosa
. We hypothesized that PQS stimulates OMV formation through direct interaction with the outer leaflet of the outer membrane. To test this hypothesis, we employed a red blood cell (RBC) model that has been used extensively to study small-molecule–membrane interactions. Our results revealed that addition of PQS to RBCs induced membrane curvature, resulting in the formation of membrane spicules (spikes), consistent with small molecules that are inserted stably into the outer leaflet of the membrane. Radiotracer experiments demonstrated that sufficient PQS was inserted into the membrane to account for this curvature and that curvature induction was specific to PQS structure. These data suggest that a low rate of interleaflet flip-flop forces PQS to accumulate in and expand the outer leaflet relative to the inner leaflet, thus inducing membrane curvature. In support of PQS-mediated outer leaflet expansion, the PQS effect was antagonized by chlorpromazine, a molecule known to be preferentially inserted into the inner leaflet. Based on these data, we propose a bilayer-couple model to describe
P. aeruginosa
OMV biogenesis and suggest that this is a general mechanism for bacterial OMV formation.

IMPORTANCE
Despite the ubiquity and importance of outer membrane vesicle (OMV) production in Gram-negative bacteria, the molecular details of OMV biogenesis are not fully understood. Early experiments showed that 2-heptyl-3-hydroxy-4-quinolone (PQS) induces OMV formation through physical interaction with the membrane but did not elucidate the mechanism. The present study demonstrates that PQS specifically and reversibly promotes blebbing of model membranes dependent upon the same properties that are required for OMV formation in
P. aeruginosa
. These results are consistent with a mechanism where expansion of the outer leaflet relative to the inner leaflet induces localized membrane curvature. This “bilayer-couple” model can account for OMV formation under all conditions and is easily generalized to other Gram-negative bacteria. The model therefore raises the possibility of a universal paradigm for vesicle production in prokaryotes with features strikingly different from what is known in eukaryotes.
Generation of a Novel Nucleic Acid-Based Reporter System To Detect Phenotypic Susceptibility to Antibiotics in Mycobacterium tuberculosis
Authors: Mulvey Matthew C. , Sacksteder Katherine A. , Einck Leo , Nacy Carol A. 
Published: March 2012

ABSTRACT

We designed, constructed, and evaluated a prototype novel reporter system comprised of two functional cassettes: (i) the SP6 RNA polymerase gene under transcriptional control of a promoter active in mycobacteria and (ii) the consensus SP6 polymerase promoter that directs expression of an otherwise unexpressed sequence. We incorporated the reporter system into a mycobacteriophage for delivery into viable
Mycobacterium tuberculosis
, and introduction led to synthesis of an SP6 polymerase-dependent surrogate marker RNA that we detected by reverse transcriptase PCR (RT-PCR). The reporter confirmed the susceptibility profile of both drug-susceptible and drug-resistant
M. tuberculosis
strains exposed to first-line antitubercular drugs and required as little as 16 h of exposure to antibacterial agents targeting bacterial metabolic processes to accurately read the reaction. The reporter system translated the bacterial phenotype into a language interpretable by rapid and sensitive nucleic acid detection. As a phenotypic assay that works only on viable
M. tuberculosis
, it could be used to rapidly assess resistance to any drug, including drugs for which the mechanism of resistance is unknown or which result from many potential known (and unknown) genetic alterations.

IMPORTANCE
The ability to detect antibiotic resistance of slow-growing bacteria (i.e.,
Mycobacterium tuberculosis
) is hampered by two factors, the time to detection (weeks to months) and the resistance mechanism (unknown for many drugs), delaying the appropriate treatment of patients with drug-resistant or multidrug-resistant tuberculosis (TB). The novel technique described in this article uses a unique surrogate nucleic acid marker produced by phage that infects
M. tuberculosis
to record phenotypic antibiotic susceptibility in less than a day.
STABLE HARMONIC MAPS BETWEEN FINSLER MANIFOLDS AND SSU MANIFOLDS
Authors: LI JINTANG 
Published: March 2012

Using the properties of Cartan tensor, we rewrite the second variation formula for harmonic maps between Finsler manifolds, and we prove that there is no non-degenerate stable harmonic map from a compact SSU manifold to any Finsler manifold, which is obtained by Howard and Wei for the Riemannian case. We also include a proof of a theorem of Shen–Wei which states that there is no non-degenerate stable harmonic map from a compact Finsler manifold to any SSU manifold, by the same second variational formula (see Eq. (2.1) in [Y. B. Shen and S. W. Wei, The stability of harmonic maps on Finster manifolds, Houston J. Math. 34 (2008) 1049–1056]) and the same method [S. W. Wei, An extrinsic average variational method, in Recent Developments in Geometry, Contemporary Mathematics, Vol. 101 (American Mathematical Society, Providence, RI, 1989), pp. 55–78].
ON THE WELL-POSEDNESS OF THE FULL LOW MACH NUMBER LIMIT SYSTEM IN GENERAL CRITICAL BESOV SPACES
Authors: DANCHIN RAPHAËL , LIAO XIAN 
Published: March 2012

This work is devoted to the well-posedness issue for the low Mach number limit system obtained from the full compressible Navier–Stokes system, in the whole space ℝd with d ≥ 2. In the case where the initial temperature (or density) is close to a positive constant, we establish the local existence and uniqueness of a solution in critical homogeneous Besov spaces of type [Formula: see text]. If, in addition, the initial velocity is small then we show that the solution exists for all positive time. In the fully nonhomogeneous case, we establish the local well-posedness in nonhomogeneous Besov spaces [Formula: see text] (still with critical regularity) for arbitrarily large data with positive initial temperature. Our analysis strongly relies on the use of a modified divergence-free velocity which allows to reduce the system to a nonlinear coupling between a parabolic equation and some evolutionary Stokes system. As in the recent work by Abidi and Paicu [Existence globale pour un fluide inhomogène, Ann. Inst. Fourier 57(3) (2007) 883–917]. Concerning the density-dependent incompressible Navier–Stokes equations, the Lebesgue exponents of the Besov spaces for the temperature and the (modified) velocity, need not be the same. This enables us to consider initial data in Besov spaces with a negative index of regularity.
SYNTHESIS OF NANOSIZE SILICON CARBIDE POWDER BY CARBOTHERMAL REDUCTION OF SiO2
Authors: DEHGHANZADEH M. , ATAIE A. , HESHMATI-MANESH S. 
Published: March 2012

A mixture of silicon carbide nano-particles and nano-whiskers has been synthesized through solid state reduction of silica by graphite employing high energy planetary ball milling for 25 h and subsequent heat treatment at 1300-1700°C in dynamic argon atmosphere. Effects of process conditions on the thermal behavior, phase composition and morphology of the samples were investigated using DTA/TGA, XRD and SEM, technique, respectively. DTA/TGA analysis shows that silicon carbide starts to form at ~ 1250°C. Analysis of the XRD patterns indicates that the phase composition of the sample heat treated at 1300°C for 2 h mainly consists of SiO 2 together with small amount of β- SiC . Nano-crystalline silicon carbide phase with a mean crystallite size of 38 nm was found to be dominate phase on heat treatment temperature at ~ 1500°C. Substantial SiO 2 was still remained in the above sample. SEM studies reveal that the sample heat treated at 1500°C for 2 h contains nano-particles and nano-whisker of β- SiC with a mean diameter of almost ~ 85 nm. The results obtained were also showed that the characteristics of the synthesized SiC particles strongly depend on the mechanical activation and heat treatment conditions.
SOLID STATE REDUCTION OF MoO3 WITH CARBON VIA MECHANICAL ALLOYING TO SYNTHESIZE NANO-CRYSTALINE MoO2
Authors: SAGHAFI M. , ATAIE A. , HESHMATI-MANESH S. 
Published: March 2012

In this research, effect of milling time on solid state reduction of MoO 3 with carbon has been investigated. It was found that mechanical activation of a mixture of MoO 3 and carbon at ambient temperature by high energy ball milling was not able to reduce MoO 3 to metallic molybdenum. MoO 3 was converted to MoO 2 at the first stage of reduction and peaks of the latter phase in X-ray diffraction patterns were detected when the milling time exceeded from 50 hours. The main effect of increased milling time at this stage was decreasing of MoO 3 peak intensities and significant peak broadening due to decrease in size of crystallites. After prolonged milling, MoO 3 was fully reduced to nano-crystalline MoO 2 and its mean crystallite size was calculated using Williamson–Hall technique and found to be 17.5 nm. Thermodynamic investigations also confirm the possibility of reduction of MoO 3 to MoO 2 during the milling operation at room temperature. But, further reduction to metallic molybdenum requires thermal activation at higher temperature near 1100 K. XRD and SEM techniques were employed to evaluate the powder particles characteristics.
OPTIMIZATION of DYNAMIC CH4 GAS HEAT TREATMENT OF NANOCRYSTALLINE STRONTIUM HEXAFERRITE
Authors: DEHGHAN R. , SEYYED EBRAHIMI S. A. , KOOHDAR H. R. 
Published: March 2012

In this research the influence of dynamic CH 4 heat treatment on Sr -hexaferrite has been investigated. With the gas heat treatment, the phase composition, particles size and the morphology of Sr -hexaferrite change significantly. Due to this, the hard magnetic nature of the material changes from hard to soft. The strontium hexaferrite powder was prepared by conventional route with calcination of the mixture of strontium carbonate and hematite at 1100°C for 1 hour. Then the resultant Sr -hexaferrite was isothermally heat treated in methane dynamic atmosphere at various temperatures and gas flows for different times. The rate of heating and cooling were 10°C/min. The optimum conditions were obtained at 950°C and 15CC/min flow for 0.5 hour. The effects of gas heat treatment on the phase composition and the particles size and morphology were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Vibration Sample Magnetometery (VSM) techniques. The results show the decomposition of Sr -hexaferrite and reduction of the resultant hematite mainly to iron. The crystallite size of the resultant iron was also measured below 50nm.
THE INFLUENCE OF GRAIN SIZE OF PURE IRON METAL ON CORROSION INHIBITION IN PRESENCE OF SODIUM NITRITE
Authors: AFSHARI VAHID , DEHGHANIAN CHANGIZ 
Published: March 2012

The effects of grain size reduction on the corrosion inhibition of sodium nitrite were investigated using polarization curves and electrochemical impedance spectroscopy (EIS). Nanocrystalline iron (~ 45 nm) was produced by pulse electrodeposition using citric acid bath. The grain size of a nanocrystalline surface was analyzed by X-ray diffractometry (XRD) and field emission scanning electron microscopy (FESEM). The most intensive first-order peak (211) of the XRD patterns was taken for detailed analysis using a Gaussian fitting curve. The tests were carried out in 25 mg / l NaCl + 57 mg / l Na 2 SO 4 with different concentration of sodium nitrite aqueous solutions. The results revealed that due to the adsorption process which leads to the formation of a protective layer with a greater charge transfer resistance the inhibition effect and corrosion protection of sodium nitrite inhibitor in near-neutral aqueous solutions increased as the grain size decreased from microcrystalline to nanocrystalline. The standard free energy of adsorption ( ΔGads ) revealed a strong interaction between inhibitor and nanocrystalline surface. This was attributed to the increased number of the active sites caused by nanocrystalline surface.
HDL Mimetics Inhibit Tumor Development in Both Induced and Spontaneous Mouse Models of Colon Cancer
Authors: Su Feng , Grijalva Victor , Navab Kaveh , Ganapathy Ekambaram , Meriwether David , Imaizumi Satoshi , Navab Mohamad , Fogelman Alan M. , Reddy Srinivasa T. , Farias-Eisner Robin 
Published: March 2012

AbstractRecent studies suggest that high-density lipoprotein (HDL) levels are inversely related to colon cancer risk. HDL mimetics constructed from a number of peptides and proteins with varying structures possess anti-inflammatory and antioxidant properties reminiscent of HDL. In this article, we examined whether HDL mimetics, L-4F (an apolipoprotein A-I mimetic peptide) and G* (an apolipoprotein J mimetic peptide) affect tumor growth and development in mouse models of colon cancer. HDL mimetics reduced viability and proliferation of CT26 cells, a mouse colon adenocarcinoma cell line, and decreased CT26 cell–mediated tumor burden in BALB/c mice when administered subcutaneously or orally. Plasma levels of lysophosphatidic acid (LPA), a serum biomarker for colon cancer, were significantly reduced in mice that received HDL mimetics, suggesting that binding and removal of proinflammatory lipids is a potential mechanism for the inhibition of tumor development by HDL mimetics. Furthermore, L-4F significantly reduced size and number of polyps in APCmin/+ mice, a mouse model for human familial adenomatous polyposis, suggesting that HDL mimetics are effective in inhibiting the development of both induced and spontaneous cancers of the colon. Our results, for the first time, identify HDL mimetics as a novel therapeutic strategy for the treatment of colon cancer. Mol Cancer Ther; 11(6); 1311–9. ©2012 AACR.
USP2a Activation of MYC in Prostate Cancer
Authors: Nelson William G. , De Marzo Angelo M. , Yegnasubramanian Srinivasan 
Published: March 2012

Abstract
Ubiquitin-specific protease 2a, a deubiquitinating enzyme, elevates MYC levels in prostate cancer cells via its stabilization of MDM2, undermining p53 regulation of microRNAs that target MYC mRNA. Cancer Discovery; 2(3); 206–7. ©2012 AACR.
Commentary on Benassi et al., p. 236.
Of Śüdras, Sütas, and Ślokas: Why is the Mahāabhārata Preeminently in the Anustubh Metre?
Authors: Sharma  
Published: March 2012

AbstractOne striking difference between Vedic and post-Vedic Hindu literature lies in the fact that while the anustubh metre is sparsely represented in the Veda as a whole, it is the standard metre of post-Vedic religious literature of Hinduism available in Sanskrit. Thus the Mahābhārata, a major document of post-Vedic Hinduism, is preeminently in the anustubh metre. How is this striking metrical fact to be explained? This paper discusses the various explanations that may be offered to account for it. In part I it discusses the explanations that could be offered on the basis of modern critical scholarship. In parts II–IX it develops the suggestion that the answer may lie in the association of the Mahābhārata with the śūdras and of the śūdras with the anustubh metre.
Thomas Zehnder: Atharvaveda-Paippalāda, eine Sammlung altindischer Zaubersprüche vom Beginn des 1. Jahrtausends v.Chr. Buch 2. Text, Übersetzung, Kommentar. Schulz-Kirchner Verlag GmbH: Wissenschaftliche Schriften, Reihe 3, Beiträge zur Sprach- und Literaturwissenschaft, Band 107
Authors: Mylius  
Published: March 2012

AbstractNo Abstract
The case of the nun Mettiyā reexamined: on the expulsion of a pregnant bhikuī in the Vinaya of the Mahāsāghikas and other Indian Buddhist monastic law codes
Authors: Clarke Shayne 
Published: March 2012

AbstractThe enigmatic story of the nun Mettiyā's expulsion from the sisterhood, seemingly for the false accusation of rape against the monk Dabba Mallaputta, has piqued the interest of modern scholars of Indian Buddhist monastic law ever since it was discussed by I.B. Horner in 1930. To date, however, no one has put forth a convincing explanation of the legal grounds for Mettiyā's expulsion. This holds true not only for modern scholars, but also it seems for the fifth century CE author(s) of the Samantapāsādikā, a commentary on the Pāli Vinaya.
VOICING AND VOICELESSNESS IN TOLKĀPPIY AM!
Authors: Govindankutty A. 
Published: March 2012

AbstractO. R. Radhakrishnan in his note “Tolkāppiyam on Intervocalic Stops” published in the Indo-Iranian Journal (Vol. IX, No.3 [1966], pp. 209-210) points out that Tolkāppiyar has used the term icaittal in the sense of “voicing” and uyirttal in the sense of “breathing". To quote him fully, “Note that icai and uyir, the stems in the two terms mentioned above, also mean respectively ‘music’ and ‘life', for which voicing and breathing are indispensable. When Tolkāppiyam describes sounds that are voiced it employs the term icai; but when it describes sounds that are voiceless it employs the term uyirttal. According to Tolkāppiyam the vowels (Sūtra 84), the nasals (Sūtra 100), and the liquids (Sūtra 99) are voiced; the stops are breathed (Sūtra 17), except when they are preceded by nasals (Sūtra 25)” (p. 210).
Heterodoxe lehren und ihre widerlegung im Kālacakra-tantra
Authors: Grönbold Günter 
Published: March 2012

AbstractAt the end of the second chapter of the Buddhist Kālacakra-Tantra (dated c. 10th century) we find a group of verses in which several doctrines are characterized and criticized: Brahmanism, Vaisnavism, Śaivism, materialism, Islam and Jainism. Moreover the text refers to Buddhism itself as well as the so-called heterodox Buddhist schools. It is the only old Sanskrit text known until now in which the Islam is mentioned and recognized as a doctrine.
Tmesis and movement in Avestan
Authors: Hale Mark 
Published: March 2012

AbstractA comparison of the facts described above for Younger Avestan with those uncovered in the discussion of Gathic Avestan reveals that tmesis in Avestan was the result of either (1) a fronting of the preverb or (2) the application of rules governing the placement of the clitics (especiallycā andvā). The fronting rule allowed movement of the preverb to a limited set of positions, normally initial position in the sentence, second position if initial position was taken up by an element in COMP, and, in metrical texts, to a major metrical boundary. Thus the relationship between a preverb and its verb was easily recoverable by the native speaker.This close relationship between tmesis and fronting is likely to be very old. The majority of hte Vedic and Greek examples can be analyzed as ‘preverb-fronting’,15 compare also Watkins (1963) for Celtic. It seems likely that the fronting of preverbs at least originally implied some emphasis on the semantics of the preverb, such emphasis being the normal function of fronting in the Proto-Indo-European clause. Tmesis without demonstrable preverb fronting is not found in the Avestan corpus, nor in Vedic prose, but it is not sufficiently rare in the Rigveda (given our current understanding of Rigvedic clause structure) to allow us to say that tmesis and preverb fronting were one and the same process for that language. The Avestan evidence surveyed here will thus prove crucial to the development of a comprehensive account of the diachronic development of tmesis in Indo-Iranian, and, therefore, in the Indo-European language family as a whole.
Distribution and Biology of Amphipods on Two Geomorphologically Different Sandy Beaches in Tunisia
Authors: Ayari Amel , Nasri-Ammar Karima 
Published: March 2012

The spatio-temporal distribution and the biology of supra-littoral amphipods were studied in spring and autumn on two Tunisian beaches: Bizerte (northern Tunisia) and the central Gulf of Gabès (southern Tunisia); the latter is characterized by the most substantial tidal amplitude in the entire Mediterranean basin.
Quadrats of 0.25 m2 were used along a transect in order to determine both quantitative and qualitative ecological parameters. The results showed that, whatever the sampling season and apart from some beetles found in spring, the only species found on Gabès beach was the supra-littoral amphipod Talitrus saltator, while on Bizerte beach three species were identified: Talitrus saltator, Deshayesorchestia deshayesii, and Orchestia gammarellus. Furthermore, the density obtained in spring was significantly high, both in Bizerte (267 individuals/m2) and Gabès (99 individuals/m2). The distribution zone of Talitrus saltator on the second sampling site was wider in spring (12.5 m) than in autumn (2.5 m), whereas the difference in the distribution of the three species of amphipods on Bizerte beach was more limited in spring (5 m) than in autumn (7 m).