bluuebunny/crossref_metadata_2025_split huggingface dataset:
Jasmonate-Dependent Induction of Indole Glucosinolates in Arabidopsis by Culture Filtrates of the Nonspecific PathogenErwinia carotovora
Authors: Brader Günter , Tas Éva , Palva E. Tapio 
Published: July 2002

Abstract
Elicitors from the plant pathogen Erwinia carotovoratrigger coordinate induction of the tryptophan (Trp) biosynthesis pathway and Trp oxidizing genes in Arabidopsis. To elucidate the biological role of such pathogen-induced activation we characterized the production of secondary defense metabolites such as camalexin and indole glucosinolates derived from precursors of this pathway. Elicitor induction was followed by a specific increase in 3-indolylmethylglucosinolate (IGS) content, but only a barely detectable accumulation of the indole-derived phytoalexin camalexin. The response is mediated by jasmonic acid as shown by lack of IGS induction in the jasmonate-insensitive mutant coi1-1. In accordance with this, methyl jasmonate was able to trigger IGS accumulation in Arabidopsis. In contrast, ethylene and salicylic acid seem to play a minor role in the response. They did not trigger alterations in IGS levels, and methyl jasmonate- or elicitor-induced IGS accumulation in NahG and ethylene-insensitiveein2-1 mutant plants was similar as in the wild type. The breakdown products of IGS and other glucosinolates were able to inhibit growth of E. carotovora. The results suggest that IGS is of importance in the defense against bacterial pathogens.
Seed-Specific Over-Expression of an Arabidopsis cDNA Encoding a Diacylglycerol Acyltransferase Enhances Seed Oil Content and Seed Weight
Authors: Jako Colette , Kumar Arvind , Wei Yangdou , Zou Jitao , Barton Dennis L. , Giblin E. Michael , Covello Patrick S. , Taylor David C. 
Published: July 2002

Abstract
We recently reported the cloning and characterization of an Arabidopsis (ecotype Columbia) diacylglycerol acyltransferase cDNA (Zou et al., 1999) and found that in Arabidopsis mutant line AS11, an ethyl methanesulfonate-induced mutation at a locus on chromosome II designated as Tag1 consists of a 147-bp insertion in the DNA, which results in a repeat of the 81-bp exon 2 in theTag1 cDNA. This insertion mutation is correlated with an altered seed fatty acid composition, reduced diacylglycerol acyltransferase (DGAT; EC 2.3.1.20) activity, reduced seed triacylglycerol content, and delayed seed development in the AS11 mutant. The effect of the insertion mutation on microsomal acyl-coenzyme A-dependent DGAT is examined with respect to DGAT activity and its substrate specificity in the AS11 mutant relative to wild type. We demonstrate that transformation of mutant AS11 with a single copy of the wild-type Tag1 DGAT cDNA can complement the fatty acid and reduced oil phenotype of mutant AS11. More importantly, we show for the first time that seed-specific over-expression of the DGAT cDNA in wild-type Arabidopsis enhances oil deposition and average seed weight, which are correlated with DGAT transcript levels. The DGAT activity in developing seed of transgenic lines was enhanced by 10% to 70%. Thus, the current study confirms the important role of DGAT in regulating the quantity of seed triacylglycerols and the sink size in developing seeds.
Hormonal Changes in the Grains of Rice Subjected to Water Stress during Grain Filling
Authors: Yang Jianchang , Zhang Jianhua , Wang Zhiqing , Zhu Qingsen , Wang Wei 
Published: July 2002

Abstract
Lodging-resistant rice (Oryza sativa) cultivars usually show slow grain filling when nitrogen is applied in large amounts. This study investigated the possibility that a hormonal change may mediate the effect of water deficit that enhances whole plant senescence and speeds up grain filling. Two rice cultivars showing high lodging resistance and slow grain filling were field grown and applied with either normal or high amount nitrogen (HN) at heading. Well-watered and water-stressed (WS) treatments were imposed 9 days post anthesis to maturity. Results showed that WS increased partitioning of fixed 14CO2 into grains, accelerated the grain filling rate but shortened the grain filling period, whereas the HN did the opposite way. Cytokinin (zeatin + zeatin riboside) and indole-3-acetic acid contents in the grains transiently increased at early filling stage and WS treatments hastened their declines at the late grain filling stage. Gibberellins (GAs; GA1 + GA4) in the grains were also high at early grain filling but HN enhanced, whereas WS substantially reduced, its accumulation. Opposite to GAs, abscisic acid (ABA) in the grains was low at early grain filling but WS remarkably enhanced its accumulation. The peak values of ABA were significantly correlated with the maximum grain filling rates (r = 0.92**,P &lt; 0.01) and the partitioning of fixed14C into grains (r = 0.95**,P &lt; 0.01). Exogenously applied ABA on pot-grown HN rice showed similar results as those by WS. Results suggest that an altered hormonal balance in rice grains by water stress during grain filling, especially a decrease in GAs and an increase in ABA, enhances the remobilization of prestored carbon to the grains and accelerates the grain filling rate.
Rab2 GTPase Regulates Vesicle Trafficking between the Endoplasmic Reticulum and the Golgi Bodies and Is Important to Pollen Tube Growth[W]
Authors: Cheung Alice Y. , Chen Christine Y.-h. , Glaven Richard H. , de Graaf Barend H. J. , Vidali Luis , Hepler Peter K. , Wu Hen-ming 
Published: July 2002

AbstractPollen tube elongation depends on the secretion of large amounts of membrane and cell wall materials at the pollen tube tip to sustain rapid growth. A large family of RAS-related small GTPases, Rabs or Ypts, is known to regulate both anterograde and retrograde trafficking of transport vesicles between different endomembrane compartments and the plasma membrane in mammalian and yeast cells. Studies on the functional roles of analogous plant proteins are emerging. We report here that a tobacco pollen-predominant Rab2, NtRab2, functions in the secretory pathway between the endoplasmic reticulum and the Golgi in elongating pollen tubes. Green fluorescent protein–NtRab2 fusion protein localized to the Golgi bodies in elongating pollen tubes. Dominant-negative mutations in NtRab2 proteins inhibited their Golgi localization, blocked the delivery of Golgi-resident as well as plasmalemma and secreted proteins to their normal locations, and inhibited pollen tube growth. On the other hand, when green fluorescent protein–NtRab2 was over-expressed in transiently transformed leaf protoplasts and epidermal cells, in which NtRab2 mRNA have not been observed to accumulate to detectable levels, these proteins did not target efficiently to Golgi bodies. Together, these observations indicate that NtRab2 is important for trafficking between the endoplasmic reticulum and the Golgi bodies in pollen tubes and may be specialized to optimally support the high secretory demands in these tip growth cells.
Site‐directed spin labeling of a bacterial chemoreceptor reveals a dynamic, loosely packed transmembrane domain
Authors: Barnakov Alexander , Altenbach Christian , Barnakova Ludmila , Hubbell Wayne L. , Hazelbauer Gerald L. 
Published: July 2002

AbstractWe used site‐directed spin labeling and electron paramagnetic resonance spectroscopy to investigate dynamics and helical packing in the four‐helix transmembrane domain of the homodimeric bacterial chemoreceptor Trg. We focused on the first transmembrane helix, TM1, particularly on the nine‐residue sequence nearest the periplasm, because patterns of disulfide formation between introduced cysteines had identified that segment as the region of closest approach among neighboring transmembrane helices. Along this sequence, mobility and accessibility of the introduced spin label were characteristic of loosely packed or solvent‐exposed side chains. This was also the case for eight additional positions around the circumference and along the length of TM1. For the continuous nine‐residue sequence near the periplasm, mobility and accessibility varied only modestly as a function of position. We conclude that side chains of TM1 that face the interior of the four‐helix domain interact with neighboring helices but dynamic movement results in loose packing. Compared to transmembrane segments of other membrane proteins reconstituted into lipid bilayers and characterized by site‐directed spin labeling, TM1 of chemoreceptor Trg is the most dynamic and loosely packed. A dynamic, loosely packed chemoreceptor domain can account for many experimental observations about the transmembrane domains of chemoreceptors.
Solubilization and disaggregation of polyglutamine peptides
Authors: Chen Songming , Wetzel Ronald 
Published: July 2002

AbstractA method is described for dissolving and disaggregating chemically synthesized polyglutamine peptides. Polyglutamine peptides longer than about Q20 have been reported to be insoluble in water, but dissolution in – and evaporation from ‐ a mixture of trifluoroacetic acid and hexafluoroisopropanol converts polyglutamine peptides up to at least Q44 to a form readily soluble in aqueous buffers. This procedure also has a dramatic effect on peptides which appear to be completely soluble in water, by removing traces of aggregate that seed aggregation. The protocol makes possible solution studies—including in vitro aggregation experiments—on polyglutamine peptides with repeat lengths associated with increased risk of Huntington's Disease and other expanded CAG repeat diseases. It may also be useful in conducting reproducible, quantitative aggregation studies on other polypeptides.
Effect of the N2 residue on the stability of the α‐helix for all 20 amino acids
Authors: Cochran Duncan A.E. , Doig Andrew J. 
Published: July 2002

AbstractN2 is the second position in the α‐helix. All 20 amino acids were placed in the N2 position of a synthetic helical peptide (CH3CO‐[AXAAAAKAAAAKAAGY]‐NH2) and the helix content was measured by circular dichroism spectroscopy at 273K. The dependence of peptide helicity on N2 residue identity has been used to determine a free‐energy scale by analysis with a modified Lifson‐Roig helix‐coil theory that includes a parameter for the N2 energy (n2). The rank order of ΔΔG(relative to Ala) is Glu−, Asp− > Ala > Glu0, Leu, Val, Gln, Thr, Ile, Ser, Met, Asp0, His0, Arg, Cys, Lys, Phe > Asn, > Gly, His+, Pro, Tyr. The results correlate very well with N2 propensities in proteins, moderately well with N1 and helix interior preferences, and not at all with N‐cap preferences. The strongest energetic effects result from interactions with the helix dipole, which favors negative charges at the helix N terminus. Hydrogen bonds to side chains at N2, such as Gln, Ser, and Thr, are weak, despite occurring frequently in protein crystal structures, in contrast to the N‐cap position. This is because N‐cap hydrogen bonds are close to linear, whereas N2 hydrogen bonds have poor geometry. These results can be used to modify protein stability rationally, help design helices, and improve prediction of helix location and stability.
A partially folded intermediate species of the β‐sheet protein apo‐pseudoazurin is trapped during proline‐limited folding
Authors: Reader John S. , Van Nuland Nico A. J. , Thompson Gary S. , Ferguson Stuart J. , Dobson Christopher M. , Radford Sheena E. 
Published: July 2002

AbstractThe folding of apo‐pseudoazurin, a 123‐residue, predominantly β‐sheet protein with a complex Greek key topology, has been investigated using several biophysical techniques. Kinetic analysis of refolding using far‐ and near‐ultraviolet circular dichroism (UV CD) shows that the protein folds slowly to the native state with rate constants of 0.04 and 0.03 min−1, respectively, at pH 7.0 and at 15°C. This process has an activation enthalpy of ∼90 kJ/mole and is catalyzed by cyclophilin A, indicating that folding is limited by trans‐cis proline isomerization, presumably around the Xaa‐Pro 20 bond that is in the cis isomer in the native state. Before proline isomerization, an intermediate accumulates during folding. This species has a substantial signal in the far‐UV CD, a nonnative signal in the near‐UV CD, exposed hydrophobic surfaces (judged by 1‐anilino naphthalenesulphonate binding), a noncooperative denaturation transition, and a dynamic structure (revealed by line broadening on the nuclear magnetic resonance time scale). We compare the properties of this intermediate with partially folded states of other proteins and discuss its role in folding of this complex Greek key protein.
Modeling the Air-Cooled Gas Turbine: Part 2—Coolant Flows and Losses
Authors: Young J. B. , Wilcock R. C. 
Published: July 2002

Abstract
This paper is Part II of a study concerned with developing a formal framework for modeling air-cooled gas turbine cycles. It deals with the detailed specification of coolant flowrates and losses. For accurate performance assessment, it is necessary to divide the turbine expansion into individual stages with stator and rotor rows being treated separately. Particular care is needed when deriving the equations for the rotor, and it is shown how all required flow variables can be estimated from minimal data if design values are unavailable. Specification of the cooling flowrates is based on a modified Holland and Thake procedure, which can be formalized in terms of averaged parameters. Thermal barrier coatings can be included if present. The importance of allowing for fluctuations in combustor outlet temperature is stressed and procedures for dealing with end-wall and disk cooling are suggested. There is confusion in the literature concerning cooling losses, and it is shown how these may be defined and subdivided in a consistent way. The importance of representing losses in terms of irreversible entropy creation rather than total pressure loss is stressed. A set of models for the components of the cooling loss are presented and sample calculations are used to illustrate the division and magnitude of the loss.
Aluminizing Behaviors of Vacuum Plasma Sprayed MCrAlY Coatings
Authors: Itoh Y. , Saitoh M. , Ishiwata Y. 
Published: July 2002

AbstractThe objective of this study is aluminide overlay coatings of MCrAlY sprayed by a vacuum plasma spraying (VPS) process for the protection against high-temperature corrosion and oxidation of gas turbine components. Diffusion coating processes have been applied for many years to improve similarly the environmental resistance by enriching the surface of nickel-based superalloys with chromium, aluminum, or silicon element. Recently, aluminizing of MCrAlY coatings is used for improving further the high-temperature oxidation resistance. However, the aluminizing properties of plasma-sprayed MCrAlY coatings, which have an important effect on the coating performance, have not been clarified. In this study, five kinds of plasma-sprayed MCrAlY (CoCrAlY, CoNiCrAlY, CoNiCrAlY+Ta, NiCrAlY, and NiCoCrAlY) coating were selected for pack-aluminizing tests. The as sprayed and the heat-treated (1393 K, 2 h, argon cooled and 1116 K, 24 h, argon cooled) MCrAlY specimens were Al-Cr-Al2O3-NH4Cl pack-aluminized at 1173, 1223, and 1273 K for 5, 10, and 20 h, respectively. The experimental results showed that the aluminizing process formed the aluminum rich layers of NiAl or CoAl phase. It also indicated that the thickness of the aluminum rich layer showed a parabolic time-dependence in all MCrAlY coatings. The order of reaction diffusion rate was NiCoCrAlY=NiCrAlY&gt;CoNiCrAlY&gt;CoNiCrAlY+Ta&gt;CoCrAlY. There was a tendency that the reaction diffusion rate by aluminizing increased with increasing nickel content in the MCrAlY coatings and the reaction diffusion rate of as sprayed MCrAlY coatings is faster than that of the heat-treated MCrAlY coatings.
A Novel In-Vitro System for the Simultaneous Exposure of Bladder Smooth Muscle Cells to Mechanical Strain and Sustained Hydrostatic Pressure
Authors: Haberstroh Karen M. , Kaefer Martin , DePaola Natacha , Frommer Sarah A. , Bizios Rena 
Published: July 2002

AbstractThe novel hydrostrain system was designed in an effort to establish and maintain conditions that simulate the in-vivo mechanical environment of the bladder. In this laboratory system, ovine bladder smooth muscle cells on flexible, 10-cm-dia silastic membranes were exposed simultaneously to hydrostatic pressure (40 cm H2O, a pressure level currently associated with bladder pathologies) and mechanical strains (up to 25 percent) under standard cell culture conditions for 7 h. Under these conditions, Heparin Binding-Epidermal Growth Factor and Collagen Type III mRNA expression were significantly increased (p&lt;0.01 and 0.1, respectively); however, no changes were observed in Collagen Type I mRNA expression. Decreases in the Collagen Type I:Type III ratio following simultaneous exposure of bladder smooth muscle cells to pathological levels of hydrostatic pressure and mechanical strain in vitro are in agreement with clinically observed increases in Collagen Type III with concomitant decreased human bladder compliance. The results of the present study, therefore, provide cellular/molecular level information relevant to bladder pathology that could have significant implications in the field of clinical urology.
Computer calculation of neutral–radical densities in a CF4 electron cyclotron resonance plasma processing system
Authors: Ashtiani K. A. , Shohet J. L. , Harvey R. E. P. 
Published: July 2002

The steady-state densities of neutral–radical species in a CF4 electron-cyclotron-resonance (ECR) plasma were calculated based on the following drift-diffusion equation: Kni(r,t)/∂t=−ℏ⋅(uin)+Di∇2ni+ ∑jnkijnj +∑j,mnjkijmnm− ni(∑jnekji +∑j,mkj imnm), where ni is the density, ui is the drift velocity, and Di is the diffusion coefficient of species i, and ne is the electron density, and k’s are the chemical rate coefficients. The above equation was solved in cylindrical coordinates using finite differences assuming symmetry in the azimuthal direction. The densities of the radical species were obtained for pressures between 1.0 and 2.5 mTorr in increments of 0.5 mTorr and the ECR power in a range between 500 and 900 W. The chemical rate coefficients were calculated directly from the convolution of electron-impact cross sections with the electron energy distribution function, and experimental plasma parameters, otherwise the best available chemical reaction rates were taken from the literature.
Diffusion coefficients were calculated from the Lennard–Jones parameters of intermolecular potential. The boundary conditions at the walls were based on available heterogeneous reactions and sticking coefficients. The electron densities entered the drift-diffusion equation directly. Results for the chemically dominant radical species such as F, CF3, and CF2 were obtained and compared with experimental measurements. The absolute magnitudes of the radical densities as predicted by the code are within an order of magnitude of the experimental measurements and in almost all cases follow the same trends as parameters are varied.
Death Receptors: Signaling and Modulation
Authors: Ashkenazi Avi , Dixit Vishva M. 
Published: July 2002

REVIEW
Apoptosis is a cell suicide mechanism that enables metazoans to control cell number in tissues and to eliminate individual cells that threaten the animal's survival. Certain cells have unique sensors, termed death receptors, on their surface. Death receptors detect the presence of extracellular death signals and, in response, they rapidly ignite the cell's intrinsic apoptosis machinery.
Why Sex and Recombination?
Authors: Barton N. H. , Charlesworth B. 
Published: July 2002

REVIEW
Most higher organisms reproduce sexually, despite the automatic reproductive advantage experienced by asexual variants. This implies the operation of selective forces that confer an advantage to sexuality and genetic recombination, at either the population or individual level. The effect of sex and recombination in breaking down negative correlations between favorable variants at different genetic loci, which increases the efficiency of natural selection, is likely to be a major factor favoring their evolution and maintenance. Various processes that can cause such an effect have been studied theoretically. It has, however, so far proved hard to discriminate among them empirically.
Resistance to Multiple Fluoroquinolones in a Clinical Isolate of
Streptococcus pyogenes
: Identification of
gyrA
and
parC
and Specification of Point Mutations Associated with Resistance
Authors: Yan S. Steve , Fox Melissa L. , Holland Steven M. , Stock Frida , Gill Vee J. , Fedorko Daniel P. 
Published: July 2002

ABSTRACT

A strain of
Streptococcus pyogenes
resistant to multiple fluoroquinolones was isolated from the blood of an immunocompromised patient. Resistance to fluoroquinolones in
S. pyogenes
has not been previously studied. Compared to 10 sensitive strains of
S. pyogenes
, the fluoroquinolone-resistant clinical isolate of
S. pyogenes
presented point mutations in
gyrA
, predicting that serine-81 was changed to phenylalanine and that methionine-99 was changed to leucine, and in
parC
, predicting that serine-79 was changed to tyrosine. The mechanism of fluoroquinolone resistance in this isolate of
S. pyogenes
appears to be analogous to previously reported mechanisms for
Streptococcus pneumoniae
.
Immunization with the
Candida albicans
Membrane Fraction and in Combination with Fluconazole Protects against Systemic Fungal Infections
Authors: Mizutani Shigetoshi , Endo Masahiro , Ino-ue Toshiaki , Kurasawa Masahiro , Uno Yoko , Saito Hideharu , Kato Ikunoshin , Takesako Kazutoh 
Published: July 2002

ABSTRACT

We studied the immunogenicity of a membrane fraction prepared from
Candida albicans
cells called
C. albicans
membrane antigen (CMA). The present study revealed that CMA immunization has antifungal activity in mouse models of systemic fungal infection. Immunization of mice by subcutaneous injections of CMA with incomplete Freund adjuvant induced resistance to infections caused not only by
C. albicans
but also by
Aspergillus fumigatus
. The level of resistance to candidiasis was as high as that induced by whole-cell immunization. The acquired resistance to candidiasis in the mice immunized with CMA was not diminished by immunosuppressive treatment with cyclophosphamide. The level of resistance to fungal infections was superior to that given by fluconazole (FLC) treatment alone and highly enhanced by the combination with FLC. When CD4
+
cells in CMA-immunized mice were depleted by a monoclonal antibody, the antifungal activity induced by the combination of CMA and FLC was significantly reduced. These results indicate that immunization with CMA is useful for preventing systemic fungal infections and in combination with FLC for increasing resistance after infection.