bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thin Aggregative Fimbriae and Cellulose Enhance Long-Term Survival and Persistence ofSalmonella
Authors: White A. P. , Gibson D. L. , Kim W. , Kay W. W. , Surette M. G. 
Published: April 2006

ABSTRACTSalmonellaspp. are environmentally persistent pathogens that have served as one of the important models for understanding how bacteria adapt to stressful conditions. However, it remains poorly understood how they survive extreme conditions encountered outside their hosts. Here we show that the rdar morphotype, a multicellular phenotype characterized by fimbria- and cellulose-mediated colony pattern formation, enhances the resistance ofSalmonellato desiccation. When colonies were stored on plastic for several months in the absence of exogenous nutrients, survival of wild-type cells was increased compared to mutants deficient in fimbriae and/or cellulose production. Differences between strains were further highlighted upon exposure to sodium hypochlorite, as cellulose-deficient strains were 1,000-fold more susceptible. Measurements of gene expression using luciferase reporters indicated that production of thin aggregative fimbriae (Tafi) may initiate formation of colony surface patterns characteristic of the rdar morphotype. We hypothesize that Tafi play a role in the organization of different components of the extracellular matrix. Conservation of the rdar morphotype among pathogenicS. entericaisolates and the survival advantages that it provides collectively suggest that this phenotype could play a role in the transmission ofSalmonellabetween hosts.
Mutational Analysis of Intervening Sequences Connecting the Binding Sites for Integration Host Factor, PepA, PurR, and RNA Polymerase in the Control Region of the
Escherichia coli carAB
Operon, Encoding Carbamoylphosphate Synthase
Authors: Devroede Neel , Huysveld Nadine , Charlier Daniel 
Published: April 2006

ABSTRACT

Transcription of the
carAB
operon encoding the unique carbamoylphosphate synthase of
Escherichia coli
reflects the dual function of carbamoylphosphate in the biosynthesis of arginine and pyrimidine nucleotides. The tandem pair of promoters is regulated by various mechanisms depending on the needs of both pathways and the maintenance of a pyrimidine/purine nucleotide balance. Here we focus on the linker regions that impose the distribution of target sites for DNA-binding proteins involved in pyrimidine- and purine-specific repression of the upstream promoter P1. We introduced deletions and insertions, and combinations thereof, in four linkers connecting the binding sites for integration host factor (IHF), PepA, PurR, and RNA polymerase and studied the importance of phasing and spacing of the targets and the importance of the nucleotide sequence of the linkers. The two PepA binding sites must be properly aligned and separated with respect to each other and to the promoter for both pyrimidine- and purine-mediated repression. Similarly, the phasing and spacing of the IHF and PEPA2 sites are strictly constrained but only for pyrimidine-specific repression. The IHF target is even dispensable for purine-mediated regulation. Thus, a correct localization of PepA within the higher-order nucleoprotein complex is a prerequisite for the establishment of pyrimidine-mediated repression and for the coupling between purine- and pyrimidine-dependent regulation. Our data also suggest the existence of a novel
cis
-acting pyrimidine-specific regulatory target located around position −60. Finally, the analysis of a P1 derivative devoid of its control region has led to a reappraisal of the effect of excess adenine on P1 and has revealed that P1 has no need for a UP element.
Mutation ofwaaC, Encoding Heptosyltransferase I inCampylobacter jejuni81-176, Affects the Structure of both Lipooligosaccharide and Capsular Carbohydrate
Authors: Kanipes Margaret I. , Papp-Szabo Erzsebet , Guerry Patricia , Monteiro Mario A. 
Published: April 2006

ABSTRACTCampylobacter jejuni81-176 lipooligosaccharide (LOS) is composed of two covalently linked domains: lipid A, a hydrophobic anchor, and a nonrepeating core oligosaccharide, consisting of an inner and outer core region. We report the isolation and characterization of the deepest roughC. jejuni81-176 mutant by insertional mutagenesis into thewaaCgene, encoding heptosyltransferase I that catalyzes the transfer of the firstl-glycero-d-manno-heptose residue to 3-deoxy-d-manno-octulosonic residue (Kdo)-lipid A. Tricine gel electrophoresis, followed by silver staining, showed that site-specific mutation in thewaaCgene resulted in the expression of a severely truncated LOS compared to wild-type strain 81-176. Gas-liquid chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy showed that thewaaCLOS species lacked all sugars distal to Kdo-lipid A. Parallel structural studies of the capsular polysaccharides of the wild-type strain 81-176 andwaaCmutant revealed loss of the 3-O-methyl group in thewaaCmutant. Complementation of theC. jejunimutant by insertion of the wild-typeC. jejuni waaCgene into a chromosomal locus resulted in LOS and capsular structures identical to those expressed in the parent strain. We also report here the presence ofO-methyl phosphoramidate in wild-type strain 81-176 capsular polysaccharide.
Mutational Analysis of the Chemoreceptor-Coupling Domain of the
Escherichia coli
Chemotaxis Signaling Kinase CheA
Authors: Zhao Jinshi , Parkinson John S. 
Published: April 2006

ABSTRACT

During chemotactic signaling by
Escherichia coli
, autophosphorylation of the histidine kinase CheA is coupled to chemoreceptor control by the CheW protein, which interacts with the C-terminal P5 domain of CheA. To identify P5 determinants important for CheW binding and receptor coupling control, we isolated and characterized a series of P5 missense mutants. The mutants fell into four phenotypic groups on the basis of in vivo behavioral and protein stability tests and in vitro assays with purified mutant proteins. Group 1 mutants exhibited autophosphorylation and receptor-coupling defects, and their CheA proteins were subject to relatively rapid degradation in vivo. Group 1 mutations were located at hydrophobic residues in P5 subdomain 2 and most likely caused folding defects. Group 2 mutants made stable CheA proteins with normal autophosphorylation ability but with defects in CheW binding and in receptor-mediated activation of CheA autophosphorylation. Their mutations affected residues in P5 subdomain 1 near the interface with the CheA dimerization (P3) and ATP-binding (P4) domains. Mutant proteins of group 3 were normal in all tests yet could not support chemotaxis, suggesting that P5 has one or more important but still unknown signaling functions. Group 4 mutant proteins were specifically defective in receptor-mediated deactivation control. The group 4 mutations were located in P5 subdomain 1 at the P3/P3′ interface. We conclude that P5 subdomain 1 is important for CheW binding and for receptor coupling control and that these processes may require substantial motions of the P5 domain relative to the neighboring P3 and P4 domains of CheA.
Structure of the Functional Form of the Mosquito Larvicidal Cry4Aa Toxin from
Bacillus thuringiensis
at a 2.8-Angstrom Resolution
Authors: Boonserm Panadda , Mo Min , Angsuthanasombat Chanan , Lescar Julien 
Published: April 2006

ABSTRACT

The Cry4Aa δ-endotoxin from
Bacillus thuringiensis
is toxic to larvae of
Culex
,
Anopheles
, and
Aedes
mosquitoes, which are vectors of important human tropical diseases. With the objective of designing modified toxins with improved potency that could be used as biopesticides, we determined the structure of this toxin in its functional form at a resolution of 2.8 Å. Like other Cry δ-endotoxins, the activated Cry4Aa toxin consists of three globular domains, a seven-α-helix bundle responsible for pore formation (domain I) and the following two other domains having structural similarities with carbohydrate binding proteins: a β-prism (domain II) and a plant lectin-like β-sandwich (domain III). We also studied the effect on toxicity of amino acid substitutions and deletions in three loops located at the surface of the putative receptor binding domain II of Cry4Aa. Our results indicate that one loop is an important determinant of toxicity, presumably through attachment of Cry4Aa to the surface of mosquito cells. The availability of the Cry4Aa structure should guide further investigations aimed at the molecular basis of the target specificity and membrane insertion of Cry endotoxins.
Functional Characterization of
Escherichia coli
GlpG and Additional Rhomboid Proteins Using an
aarA
Mutant of
Providencia stuartii
Authors: Clemmer Katy M. , Sturgill Gwen M. , Veenstra Alexander , Rather Philip N. 
Published: April 2006

ABSTRACT

The
Providencia stuartii
AarA protein is a member of the rhomboid family of intramembrane serine proteases and required for the production of an extracellular signaling molecule that regulates cellular functions including peptidoglycan acetylation, methionine transport, and cysteine biosynthesis. Additional
aarA-
dependent phenotypes include (i) loss of an extracellular yellow pigment, (ii) inability to grow on MacConkey agar, and (iii) abnormal cell division. Since these phenotypes are easily assayed, the
P. stuartii aarA
mutant serves as a useful host system to investigate rhomboid function. The
Escherichia coli
GlpG protein was shown to be functionally similar to AarA and rescued the above
aarA
-dependent phenotypes in
P. stuartii
. GlpG proteins containing single alanine substitutions at the highly conserved catalytic triad of asparagine (N154A), serine (S201A), or histidine (H254A) residues were nonfunctional. The
P. stuartii aarA
mutant was also used as a biosensor to demonstrate that proteins from a variety of diverse sources exhibited rhomboid activity. In an effort to further investigate the role of a rhomboid protein in cell physiology, a
glpG
mutant of
E. coli
was constructed. In phenotype microarray experiments, the
glpG
mutant exhibited a slight increase in resistance to the β-lactam antibiotic cefotaxime.
Gefitinib Therapy in Advanced Bronchioloalveolar Carcinoma: Southwest Oncology Group Study S0126
Authors: West Howard L. , Franklin Wilbur A. , McCoy Jason , Gumerlock Paul H. , Vance Ralph , Lau Derick H.M. , Chansky Kari , Crowley John J. , Gandara David R. 
Published: April 2006

Purpose Advanced bronchioloalveolar carcinoma (BAC) is a distinct subtype of non–small-cell lung cancer (NSCLC) for which there is currently no optimal therapy. Based on preclinical and clinical data suggesting relevance of the epidermal growth factor receptor (EGFR) axis in BAC, the Southwest Oncology Group initiated a phase II trial (S0126) to evaluate the EGFR tyrosine kinase inhibitor gefitinib in chemotherapy-naïve and chemotherapy-pretreated patients with advanced BAC. Methods A total of 136 eligible and assessable patients (101 untreated, 35 previously treated) received gefitinib 500 mg daily until progression or prohibitive toxicity. Results The median age was 68.0 years (range, 34.3 to 88.6); 51% were female; 89% had a performance status (PS) of 0% or 1% and 11% had a PS of 2. The Response Evaluation Criteria in Solid Tumors response rate was 17%, with 6% complete responses (CRs) among 69 previously untreated patients with measurable disease, and 9% with no CRs among 22 pretreated patients. Median survival was 13 months for both chemo-naïve (95% CI, 8 to 18) and previously treated patients (95% CI, 6 to 17). Overall survival at 3 years was 23% (95% CI, 14% to 32%). Toxicity consisted mainly of rash and diarrhea, but 2% of patients died of presumed interstitial lung disease. Exploratory subset analyses revealed improved survival among women (P = .031), patients developing a rash (P = .003), never-smokers (P = .061), and patients with a PS of 0 or 1 (P = .015). Conclusion Gefitinib is an active agent in advanced stage BAC. Several subsets demonstrate significantly improved clinical outcomes.
Sensorineural Hearing Loss After Radiotherapy and Chemoradiotherapy: A Single, Blinded, Randomized Study
Authors: Low Wong Kein , Toh Song Tar , Wee Joseph , Fook-Chong Stephanie M.C. , Wang De Yun 
Published: April 2006

Purpose The synergistic ototoxicity of radiation and cisplatin (CDDP) has not been adequately studied. This study investigated whether the use of concurrent and postradiotherapy CDDP in patients with nasopharyngeal carcinoma (NPC) resulted in a difference in postradiotherapy sensorineural hearing when compared with the use of radiotherapy alone. Patients and Methods Newly diagnosed patients were randomly assigned to the radiotherapy or chemoradiotherapy groups. Bone conduction hearing thresholds were performed before treatment and at 1 week, 6 months, 1 year, and 2 years after completion of radiotherapy. Statistical analysis was performed using the Mann-Whitney U test. Results Hearing thresholds averaged over 0.5, 1, and 2 kHz were found to be poorer in the chemoradiotherapy group (58 patients) compared with the radiotherapy group (57 patients) at 1 year (P = .001) and 2 years (P = .03) after radiotherapy. Hearing thresholds at 4 kHz were significantly worse for patients in the chemoradiotherapy arm at all of the postradiotherapy time points studied and were more severely affected than the thresholds at lower speech frequencies. In the radiotherapy group, deterioration of median hearing thresholds, which occurred in the immediate post-treatment period, improved within the first year but deteriorated again at 2 years. In the chemoradiotherapy group, median hearing threshold deterioration, which started immediately after radiotherapy, stabilized by 1 year. Conclusion Patients with NPC who received radiotherapy and concurrent/adjuvant chemotherapy using CDDP experienced greater sensorineural hearing loss compared with patients treated with radiotherapy alone, especially to high-frequency sounds in the speech range. Normal inner ear tissue tolerance, which was once defined only for radiotherapy patients alone, should be redefined in chemoradiotherapy patients.
Size, strength and allometry of joints in the articulated corallineCalliarthron
Authors: Martone Patrick T. 
Published: April 2006

SUMMARYArticulated coralline algae (Corallinales, Rhodophyta) dominate low-intertidal, wave-exposed habitats around the world, yet the mechanics of this diverse group of organisms has been almost completely unexplored. In contrast to fleshy seaweeds, articulated corallines consist of calcified segments (intergenicula) separated by uncalcified joints (genicula). This jointed construction makes calcified fronds as flexible as fleshy seaweeds,allowing them to `go with the flow' when struck by breaking waves. In addition to functioning as joints, genicula act as breakage points along articulated fronds. Here, I describe the allometric scaling of geniculum size, breaking force and tissue strength along articulated fronds in two species of Calliarthron. Genicular material is much stronger than tissue from fleshy macroalgae. Moreover, as fronds grow, genicula get bigger and their tissue strengthens, two processes that help them resist breakage. Within individual fronds, larger branches, which presumably experience greater drag force, are supported by bigger, stronger genicula. However, frond growth greatly outpaces genicular strengthening. As a result, Calliarthronfronds most likely break at their bases when critically stressed by incoming waves. Shedding fronds probably reduces the drag force that threatens to dislodge coralline crusts and may constitute a reproductive strategy.
Terrestrial locomotion of the New Zealand short-tailed batMystacina tuberculataand the common vampire batDesmodus rotundus
Authors: Riskin Daniel K. , Parsons Stuart , Schutt William A. , Carter Gerald G. , Hermanson John W. 
Published: April 2006

SUMMARYBats (Chiroptera) are generally awkward crawlers, but the common vampire bat (Desmodus rotundus) and the New Zealand short-tailed bat(Mystacina tuberculata) have independently evolved the ability to manoeuvre well on the ground. In this study we describe the kinematics of locomotion in both species, and the kinetics of locomotion in M. tuberculata. We sought to determine whether these bats move terrestrially the way other quadrupeds do, or whether they possess altogether different patterns of movement on the ground than are observed in quadrupeds that do not fly. Using high-speed video analyses of bats moving on a treadmill, we observed that both species possess symmetrical lateral-sequence gaits similar to the kinematically defined walks of a broad range of tetrapods. At high speeds, D. rotundus use an asymmetrical bounding gait that appears to converge on the bounding gaits of small terrestrial mammals, but with the roles of the forelimbs and hindlimbs reversed. This gait was not performed by M. tuberculata.Many animals that possess a single kinematic gait shift with increasing speed from a kinetic walk (where kinetic and potential energy of the centre of mass oscillate out of phase from each other) to a kinetic run (where they oscillate in phase). To determine whether the single kinematic gait of M. tuberculata meets the kinetic definition of a walk, a run, or a gait that functions as a walk at low speed and a run at high speed, we used force plates and high-speed video recordings to characterize the energetics of the centre of mass in that species. Although oscillations in kinetic and potential energy were of similar magnitudes, M. tuberculata did not use pendulum-like exchanges of energy between them to the extent that many other quadrupedal animals do, and did not transition from a kinetic walk to kinetic run with increasing speed. The gait of M. tuberculata is kinematically a walk,but kinetically run-like at all speeds.
The geometry of isoparametric hypersurfaces with four distinct principal curvatures in spheres
Authors: Immervoll Stefan 
Published: April 2006

Abstract
In this paper, we address three problems in the theory of incidence structures associated with isoparametric hypersurfaces with four distinct principal curvatures in spheres. In [4], we showed that these isoparametric hypersurfaces and their focal manifolds yield Tits buildings of type C2. Here, we ﬁrst give a short proof for the description of point rows and line pencils in these incidence structures. Furthermore, we provide criteria which characterize intersecting lines (or points which can be joined by a line, respectively) and obtain a simple description of the intersection point (the joining line, respectively). Finally, we describe for each antiﬂag (p,L) the position of the uniquely determined ﬂag (q, K ) such that (p, K, q, L) is a 3-chain. In this paper, we make extensive use of the theory of isoparametric triple systems as developed in [1].
A lower bound for the second sectional geometric genus of polarized manifolds
Authors: Fukuma Yoshiaki 
Published: April 2006

Abstract
Let (X, L) be a polarized manifold deﬁned over ℂ with dim
X = n ≥ 3 and let (M, A ) be a reduction of
(X, L). In this paper, if X is not uniruled and
KM
+ (n - 2)A is nef
and (n - 2)-big, then we give a lower bound for
c
2(M )A

n - 2, which
improves a result in a previous paper. By using this bound, we prove that
g
2 (X, L) ≥ h
1(## add figure
'advg.5.3.431_01.gif' ##
x ) if n ≥ 3, X is not
uniruled, and KM
+ (n - 2)A is nef
and (n - 2)-big, where g
2 (X, L) is the second sectional geometric genus of (X, L). In
particular, if n ≥ 3 and κ (X ) ≥ 0, then
g
2 (X, L) ≥ h
1(## add figure
'advg.5.3.431_01.gif' ##
x ). Furthermore we prove that g
2 (X, L) ≥ 0 for any polarized 3-folds. For
n ≥ 3 we also study (X, L) with
g
2 (X, L) ≥ h
1(## add figure
'advg.5.3.431_01.gif' ##x ). Finally we consider a lower bound of
h
0(KX
+ L) for polarized
3-folds (X, L

).
How fictive dynamicity motivates aspect marking: The riddle of the Finnish quasi-resultative construction
Authors: Huumo Tuomas 
Published: April 2006

Abstract
This article studies fictive dynamicity as a factor motivating aspectual case marking in Finnish. In Finnish transitive sentences aspect is marked with the morphological case of the object: the restrictive object is used in sentences with a resultative meaning, whereas the partitive object is used in sentences indicating either atelicity, irresultativity, or progressivity. Interestingly, however, the restrictive object is also used in so-called quasi-resultative sentences, the aspectual meaning of which is atelic. These typically express a static physical location, perception, or cognition. In this article I argue that the use of the restrictive object in quasi-resultative sentences reflects the telic features of the conceptualization used to construct the representation of the atelic situation, where the atelic situation is represented as the result of a fictive change. This study thus extends the concept of fictive dynamicity to cover phenomena related to linguistic aspect.
Addressing an audience: Time, place, and genre in Peter van Straaten’s calendar cartoons
Authors: Forceville Charles 
Published: April 2006

AbstractCartoons, like other forms of mass media, are aimed not just at anybody, but at a multitude of individuals. The extent to which these numerous individuals understand the cartoons in the same way depends not only on their shared interpretations of the word and image texts themselves, but also on interpretation strategies suggested by the (near)identical circumstances under which the cartoons are accessed. As Gail Dines points out, ‘‘locating cartoons within the cultural realm of mass communication requires an understanding of how these media forms come into existence and how they are consumed by the intended audience’’ (1995: 238). To understand better how cartoons are processed, it is necessary to generalize about contextual factors governing their perception. In this paper I examine cartoons by the Dutchman Peter van Straaten that all appeared on a tear-off calendar in the year 2001. The question addressed is how the temporal and spatial circumstances under which the cartoons are accessed, in combination with the generic conventions of the calendar in which they appear, trigger the activation of specific cognitive schemata, and thus steer and constrain possible interpretations. The general framework in which these matters are discussed is Sperber and Wilson’s (1995) Relevance Theory.
China’s Biotechnology Industry and the International Protection of Intellectual Property Rights
Authors: Loppacher Laura J. , Kerr William A. 
Published: April 2006

AbstractIntellectual property rights were an anathema to the Marxist philosophy that dominated China for the second half of the 20th century. China's recent economic reforms have recognised the need for property rights in a market-oriented economy. Further, China's accession to the market oriented World Trade Organization (WTO) requires that it become legally compliant with the WTO's Agreement on Trade Related Aspects of Intellectual Property (TRIPS). China has, however, struggled to put in place an effective legal regime for intellectual property. Agricultural biotechnology is a knowledge industry. While China has worked hard to develop a domestic biotechnology industry, it is almost entirely funded by the government. Both because the investment demands of the Chinese biotechnology industry exceed the funds that can be made available by the government and to fully capitalize on the industry's potential requires the participation of foreign biotechnology firms, intellectual property protection for biotechnology has become of central importance to its future development. This paper reviews the progress China has made in putting in place an internationally compliant intellectual property regime for biotechnology. The constraints and prospects for the future development of the biotechnology industry in China are reviewed.The TRIPS Agreement, which came into effect on 1 January 1995, is to date the most comprehensive multilateral agreement on intellectual property. (World Trade Organization, 2004a, p.1)