bluuebunny/crossref_metadata_2025 huggingface dataset:
Zeeman nuclear quadrupole resonance line shapes in powders (I = 3/2)
Authors: Brooker H. R. , Creel R. B.
Published: February 2004

Theoretical absorption line shapes are presented for Zeeman perturbed nuclear quadrupole resonance transitions (I = 3/2) in polycrystalline materials for the case in which the rf field is parallel to the Zeeman field. For a nuclear spin of 3/2, the pure quadrupole transition frequency νQ(1+η2/3)1/2 is insufficient to independently determine either νQ, the strength of the quadrupole interaction, or η, the asymmetry in the electric field gradient tensor. Application of a magnetic field removes the degeneracy of the energy levels producing, in general, four orientation dependent transition frequencies from which the quadrupole parameters can be determined. Computer simulated powder lineshapes are presented which are exact in η and are to first order in applied magnetic field strength. Frequencies of the features of the line shape are plotted as a function of η. The features of the line shape are due to crystallites aligned such that the applied field is parallel to one of the principal axes of the electric field gradient tensor. The combined nuclear electric quadrupole and nuclear Zeeman Hamiltonian has been solved exactly for these special orientations. Exact frequency expressions are calculated for these orientations of field with respect to sample. These correspond to the frequencies of the features of the line shape.
Global theorems for species distributions governed by reaction-diffusion equations
Authors: Rosen Gerald
Published: February 2004

For an essentially nonlinear reaction-diffusion equation of the form ∂c/∂t = D▿2c + Q(c) supplemented with a Robin type boundary condition over the surface of a closed bounded three-dimensional region R, it is shown that any solution for the concentration distribution c=c(x, t) in R is restricted to a prescribed Hilbert space neighborhood of any steady state solution c̄ = c̄(x) for a generic reaction rate expression Q(c). Under certain derived conditions, the Hilbert space neighborhood shrinks to zero with increasing time, implying that there is only one unique steady state solution, while under more general circumstances a Hilbert space proximity condition is obtained for any pair of steady state solutions. By introducing a special functional that is constant with time for a steady state solution and monotone-decreasing otherwise, necessary conditions for a dynamical transition between a pair of steady state solutions are deduced. From the latter results follow sufficient conditions which guarantee the uniqueness of the steady state solution and a lower bound on the transition time for dynamical evolution from one (perturbed unstable) steady state solution to another in cases of multiplicity.
Sources of rotational cross section asymmetry σ(J→J + ΔJ)/σ(J→J - ΔJ) in molecule-atom and molecule-molecule systems
Authors: Verter Michael R. , Rabitz Herschel
Published: February 2004

Asymmetries are investigated for the rotationally inelastic transitions J→J + ΔJ and J→J - ΔJ. Previous cross section expressions are extended to handle the case of two colliding symmetric top molecules. Asymmetries are shown to arise from (1) the previously considered interference terms in the cross sections, (2) angular momentum coupling effects, and (3) R⇄T energetic effects. It is shown that symmetric top molecules with threefold or higher symmetry axes are not likely to exhibit interference asymmetries unless high-order tensor terms are important in the intermolecular potential. However, substantial asymmetries can still arise from angular momentum coupling and energetic effects. The conditions for the dominance of these sources of asymmetry are discussed and investigated numerically for the molecules HCl, HCN, and OCS perturbed by Ar and Xe as well as the systems HCl:HCl, HCN:HCN, OCS:OCS, HCl:OCS, and NH3:NH3. In these latter cases, the first molecule in each pair is the observed species and the second constitutes a thermal bath. Angular momentum coupling asymmetries are found to be important only at small J. Energetic asymmetries are particularly important for systems with large rotational constants.
Investigation of the crystal field in rare-earth doped scheelites
Authors: Vishwamittar  , Puri S. P.
Published: February 2004

The crystalline fields in rare-earth doped scheelites are examined, and it is shown that the angular overlap model is inadequate to account for the results. The analysis of Yb3+ crystal field parameters under the assumption of the superposition model leads to surprisingly small exponents and large second- and fourth-order intrinsic parameters, which have been determined quite accurately. The difference of the findings from those in the other O2− ligated systems is attributed to the strong binding in XO42− complexes. The intrinsic parameters for an actinide (Np4+) are reported for the first time, and their large magnitude is ascribed to the large spatial expansion of the 5f orbitals. The transformation of the coordinate systems to eliminate one or both of the imaginary crystal field parameters is discussed in the framework of the superposition model. Also included is the analysis of the zero-field splitting of Gd3+ in these crystals.
Electronic structure of Fe2+ in normal human hemoglobin and its isolated subunits
Authors: Huynh B. H. , Papaefthymiou G. C. , Yen C. S. , Groves J. L. , Wu C. S.
Published: February 2004

A comparison study of the Mössbauer spectra of deoxy Hb-A (low oxygen affinity) and its isolated α and β subunits (high oxygen affinity) was carried out over the temperature range 77–200°K. Within experimental error, no difference was detected between these three proteins, either in the isomeric shifts or in the quadrupole splittings. These results show that the characteristically different oxygen affinity of deoxy Hb-A and its isolated subunits is not a consequence of different electronic states for the ferrous ions in Hb-A and its isolated subunits. The electronic structure of the ferrous ion in hemoglobin was determined using a crystal field approximation. The adjustable parameters in the crystal field model were systematically searched for an electronic level configuration that would give good agreement with the experimental data of the temperature-dependent quadrupole splitting and magnetic susceptibility of deoxy Hb-A. The resulting low lying energy levels in order of increasing energy were 5B2, 1A1, 5E, and 3E. The spin and orbital degeneracy of these levels were removed by the spin-orbit interaction and the rhombic perturbation of the crystalline field. The electronic ground state obtained produces an electric field gradient at the iron nucleus with a principal component of 0.11 e parallel to the heme plane and an asymmetry parameter η = 0.51.
Transient emission, off-resonant transient absorption, and Fourier transform microwave spectroscopy
Authors: McGurk J. C. , Mäder H. , Hofmann R. T. , Schmalz T. G. , Flygare W. H.
Published: February 2004

Transient emission and off-resonant absorption methods are used to measure T2 in different M states of several (J,K) transitions in 15NH3 and in the J=1→2, M=0,±1 transitions in OCS. No M dependence in T2 was observed. Transient emission signals were recorded and Fourier transformed in several (J,K) 15NH3 transitions, some of which were doublets. Faithful spectra are obtained, and the time domain experiments hold some advantage in high-resolution microwave spectroscopy over the normal steady state technique.
Electron capture and excitation in collisions of He2+ with H. II Convergence of the atomic expansion
Authors: Rapp Donald
Published: February 2004

Cross sections for excitation and single electron capture in collisions of He2+ with H(1s) were calculated in a travelling wave atomic orbital, impact parameter model. Previous calculations utilized either seven or eight state expansions, and unfortunately the eight state calculations contained an error. In this paper, the eight state calculations are corrected and in addition, 11 state results are also presented. The theory is compared with new data, and while the theoretical cross section for total exchange is in moderate agreement with experiment, the cross section for electron capture into the 2s state of He+ shows a large divergence between theory and experiment.
Beam maser measurements of distortion effects on quadrupole coupling in NH3
Authors: Ruben David J. , Kukolich Stephen G.
Published: February 2004

High resolution (350 Hz) measurements of hyperfine structure on the J=5, K=3 inversion transition in NH3 are reported. The average nitrogen quadrupole coupling strength is −393.90±0.08 kHz. This value is in excellent agreement with a value predicted by Hougen's theory describing distortion corrections to quadrupole coupling in NH3 and does not agree with a value calculated without the correction. The line center frequency and other hyperfine structure parameters are given.
High resolution inelastic tunneling spectroscopy of macromolecules and adsorbed species with liquid-phase doping
Authors: Simonsen Michael G. , Coleman R. V. , Hansma Paul K.
Published: February 2004

The vibrational spectra of organic molecules can be measured with inelastic electron tunneling if the molecules can be deposited onto the insulating layer of a thin film metal-insulator-metal tunneling junction. A new technique, liquid-phase doping, simplifies that deposition. Further, it makes it possible to deposit macromolecules and other compounds that decompose before evaporating, minimizes contamination problems, and gives higher resolution spectra than the usual vapor-phase doping. Spectra of anthracene, a high symmetry molecule, show that both Raman and infrared active modes are present in inelastic tunneling spectra with comparable intensity. Spectra of amino acids, proteins, purine and pyrimidine bases, nucleotides, and nucleic acids illustrate the applicability of the technique to a wide range of compounds of biological interest. A detailed comparison of a tunneling spectrum of benzaldehyde to recent infrared and Raman spectra of aluminum benzoate and benzaldehyde adsorbed on alumina shows the potential of the technique for studying surface reactions and possible catalysis.
Electronic structure of UF6−
Authors: Boring Michael , Wood John H. , Moskowitz J. W.
Published: February 2004

The SCF-X α-SW method is used to carry out an approximate Hartree-Fock calculation on the electronic structure on UF6−. The charge density within the atomic spheres is analyzed into its angular momentum components and the first two excited electronic states are computed.
Rotational diffusion and triplet state processes in dye laser solutions
Authors: Phillion D. W. , Kuizenga D. J. , Siegman A. E.
Published: February 2004

A cw dye laser with a rotatable intracavity Brewster-angle plate can be forced to oscillate with its signal polarization rotated by an arbitrary angle β about the laser axis from the pumping laser polarization. The threshold pump power R(β) then increases as the signal polarization is rotated from parallel (β = 0°) to perpendicular (β = 90°). By measuring the ratio R(90°)/R(0°) and comparing it with the first excited singlet level fluorescence intensity ratio I(0°)/I(90°) measured in the same laser medium below threshold, it is possible to determine the important dye laser triplet state parameter KT ≡ kSTτTσT/σe. A detailed analysis of this new triplet measurement method is given. Both the orientational distribution of the excited state population and the gain for arbitrary polarizations and pumping geometry are calculated. Triplet state effects have been studied for Rhodamine 6G as a function of dye and soap concentration in H2O. The triplet state parameter KT is found to have the value 0.35 ± 0.02 at 5960 Å for a 5 × 10−4 M concentration of R6G in water with 2% by volume of Triton X-100, and 0.25 ± 0.02 for the same dye concentration with 4% by volume of Ammonyx LO. The very long rotational relaxation times measured (∼ 1–2 nsec) indicate rigid attachment of the R6G molecules to micelle soap complexes. Evidence of intermolecular energy transfer via dipolar coupling at higher dye concentrations is observed.
Discreteness-of-charge effects and the transfer coefficient in electrode kinetics
Authors: Fawcett W. R.
Published: February 2004

The role of discreteness-of-charge effects in the kinetics of heterogeneous electron transfer and their influence on the magnitude of the experimentally observed transfer coefficient are described for reactions at the metal/electrolyte solution interface. The magnitude of these effects is estimated for the case that the reaction takes place in the inner part of the double layer. The results are discussed with respect to pertinent experimental data.
Characterization of a gene cluster encoding the maleylacetate reductase from Ralstonia eutropha 335T, an enzyme recruited for growth with 4-fluorobenzoate
Authors: Seibert Volker , Thiel Monika , Hinner Isabelle-S. , Schlömann Michael
Published: February 2004

A gene cluster containing a gene for maleylacetate reductase (EC 1.3.1.32) was cloned from Ralstonia eutropha 335T (DSM 531T), which is able to utilize 4-fluorobenzoate as sole carbon source. Sequencing of this gene cluster showed that the R. eutropha 335T maleylacetate reductase gene, macA, is part of a novel gene cluster, which is not related to the known maleylacetate-reductase-encoding gene clusters. It otherwise comprises a gene for a hypothetical membrane transport protein, macB, possibly co-transcribed with macA, and a presumed regulatory gene, macR, which is divergently transcribed from macBA. MacA was found to be most closely related to TftE, the maleylacetate reductase from Burkholderia cepacia AC1100 (62 % identical positions) and to a presumed maleylacetate reductase from a dinitrotoluene catabolic gene cluster from B. cepacia R34 (61 % identical positions). By expressing macA in Escherichia coli, it was confirmed that macA encodes a functional maleylacetate reductase. Purification of maleylacetate reductase from 4-fluorobenzoate-grown R. eutropha 335T cells allowed determination of the N-terminal sequence of the purified protein, which was shown to be identical to that predicted from the cloned macA gene, thus proving that the gene is, in fact, recruited for growth of R. eutropha 335T with this substrate.
Pseudomonas syringae pv. phaseolicola can be separated into two genetic lineages distinguished by the possession of the phaseolotoxin biosynthetic cluster
Authors: Oguiza José A. , Rico Arantza , Rivas Luis A. , Sutra Laurent , Vivian Alan , Murillo Jesús
Published: February 2004

The bean (Phaseolusspp.) plant pathogenPseudomonas syringaepv. phaseolicola is characterized by the ability to produce phaseolotoxin (Tox+). We recently reported that the majority of the SpanishP. syringaepv. phaseolicola population is unable to synthesize this toxin (Tox−). These Tox−isolates appear to lack the entire DNA region for the biosynthesis of phaseolotoxin (argK-toxgene cluster), as shown by PCR amplification and DNA hybridization using DNA sequences specific for separated genes of this cluster. Tox+and Tox−isolates also showed genomic divergence that included differences in ERIC-PCR and arbitrarily primed-PCR profiles. Tox+isolates showed distinct patterns of IS801genomic insertions and contained a chromosomal IS801insertion that was absent from Tox−isolates. Using a heteroduplex mobility assay, sequence differences were observed only among the intergenic transcribed spacer of the five rDNA operons of the Tox−isolates. The techniques used allowed the unequivocal differentiation of isolates ofP. syringaepv. phaseolicola from the closely related soybean (Glycine max) pathogen,P. syringaepv. glycinea. Finally, a pathogenicity island that is essential for the pathogenicity ofP. syringaepv. phaseolicola on beans appears to be conserved among Tox+, but not among Tox−isolates, which also lacked the characteristic large plasmid that carries this pathogenicity island. It is proposed that the results presented here justify the separation of the Tox+and Tox−P. syringaepv. phaseolicola isolates into two distinct genetic lineages, designated Pph1 and Pph2, respectively, that show relevant genomic differences that include the pathogenicity gene complement.
Differential surface localization and temperature-dependent expression of the Candida albicans CSH1 protein
Authors: Singleton David R. , Hazen Kevin C.
Published: February 2004

Cell-surface hydrophobicity (CSH) in Candida albicans contributes to virulence and can be conveniently regulated in planktonic cultures by altering growth temperature. The CSH1 gene is the first candidate gene that has been demonstrated to play a role in affecting the CSH phenotype. However, the primary amino acid sequence of the CSH1 gene product suggests that the protein should be restricted to the cytoplasm. A majority of the protein appears to demonstrate that localization. Cell-surface biotinylation and limited glucanase digestion were used to determine and estimate the relative amount of Csh1p in the extracellular compartment in comparison to the cytoplasmic pool. Additionally, Western and Northern blotting were used to assess expression of the CSH1 gene under different growth conditions. Compared with cells grown at 23 °C, the total cellular levels of Csh1p are significantly greater at elevated growth temperatures. Detection of Csh1p on the cell surface correlates with the level of overall protein expression. The temperature-dependent regulation and surface presentation of Csh1p suggests a mechanism for regulating the CSH phenotype.
Macro-array and bioinformatic analyses reveal mycobacterial ‘core’ genes, variation in the ESAT-6 gene family and new phylogenetic markers for the Mycobacterium tuberculosis complex
Authors: Marmiesse Magali , Brodin Priscille , Buchrieser Carmen , Gutierrez Christina , Simoes Nathalie , Vincent Veronique , Glaser Philippe , Cole Stewart T. , Brosch Roland
Published: February 2004

To better understand the biology and the virulence determinants of the two major mycobacterial human pathogensMycobacterium tuberculosisandMycobacterium leprae, their genome sequences have been determined recently.In silicocomparisons revealed that among the 1439 genes common to bothM. tuberculosisandM. leprae, 219 genes code for proteins that show no similarity with proteins from other organisms. Therefore, the latter ‘core’ genes could be specific for mycobacteria or even for the intracellular mycobacterial pathogens. To obtain more information as to whether these genes really were mycobacteria-specific, they were included in a focused macro-array, which also contained genes from previously defined regions of difference (RD) known to be absent fromMycobacterium bovisBCG relative toM. tuberculosis. Hybridization of DNA from 40 strains of theM. tuberculosiscomplex andin silicocomparison of these genes with the near-complete genome sequences fromMycobacterium avium,Mycobacterium marinumandMycobacterium smegmatiswere undertaken to answer this question. The results showed that among the 219 conserved genes, very few were not present in all the strains tested. Some of these missing genes code for proteins of the ESAT-6 family, a group of highly immunogenic small proteins whose presence and number is variable among the genomically highly conserved members of theM. tuberculosiscomplex. Indeed, the results suggest that, with few exceptions, the ‘core’ genes conserved amongM. tuberculosisH37Rv andM. lepraeare also highly conserved among other mycobacterial strains, which makes them interesting potential targets for developing new specific anti-mycobacterial drugs. In contrast, the genes from RD regions showed great variability among certain members of theM. tuberculosiscomplex, and some new specific deletions inMycobacterium canettii,Mycobacterium microtiand seal isolates were identified and further characterized during this study. Together with the distribution of a particular 6 or 7 bp micro-deletion in the gene encoding the polyketide synthasepks15/1, these results confirm and further extend the revised phylogenetic model for theM. tuberculosiscomplex recently presented.
Physiological implications of class IIa bacteriocin resistance in Listeria monocytogenes strains
Authors: Vadyvaloo Viveka , Snoep Jacky L. , Hastings John W. , Rautenbach Marina
Published: February 2004

High-level resistance to class IIa bacteriocins has been directly associated with the absent EIIABMan(MptA) subunit of the mannose-specific phosphoenolpyruvate-dependent phosphotransferase system (PTS) () inListeria monocytogenesstrains. Class IIa bacteriocin-resistant strains used in this study were a spontaneous resistant,L. monocytogenesB73-MR1, and a defined mutant,L. monocytogenesEGDe-mptA. Both strains were previously reported to have the EIIABManPTS component missing. This study shows that these class IIa bacteriocin-resistant strains have significantly decreased specific growth and glucose consumption rates, but they also have a significantly higher growth yield than their corresponding wild-type strains,L. monocytogenesB73 andL. monocytogenesEGDe, respectively. In the presence of glucose, the strains showed a shift from a predominantly lactic-acid to a mixed-acid fermentation. It is here proposed that elimination of the EIIABManin the resistant strains has caused a reduced glucose consumption rate and a reduced specific growth rate. The lower glucose consumption rate can be correlated to a shift in metabolism to a more efficient pathway with respect to ATP production per glucose, leading to a higher biomass yield. Thus, the cost involved in obtaining bacteriocin resistance, i.e. losing substrate transport capacity leading to a lower growth rate, is compensated for by a higher biomass yield.
alr0117, a two-component histidine kinase gene, is involved in heterocyst development in Anabaena sp. PCC 7120
Authors: Ning Degang , Xu Xudong
Published: February 2004

Anabaena sp. PCC 7120 was mutagenized by transposon Tn5-1087b, generating a mutant whose heterocysts lack the envelope polysaccharide layer. The transposon was located between nucleotides 342 and 343 of alr0117, a 918 bp gene encoding a histidine kinase for a two-component regulatory system. Complementation of the mutant with a DNA fragment containing alr0117 and targeted inactivation of the gene confirmed that alr0117 is involved in heterocyst development. RT-PCR showed that alr0117 was constitutively expressed in the presence or absence of a combined-nitrogen source. hepA and patB, the two genes turned on during wild-type heterocyst development, were no longer activated in an alr0117-null mutant. The two-component signal transduction system involving alr0117 may control the formation of the envelope polysaccharide layer and certain late events essential to the function of heterocysts.
Biochemical characterization of a Rhizobium etli monovalent cation-stimulated acyl-coenzyme A carboxylase with a high substrate specificity constant for propionyl-coenzyme A
Authors: Dunn Michael F. , Araíza Gisela , Mora Jaime
Published: February 2004

Biotin has a profound effect on the metabolism of rhizobia. It is reported here that the activities of the biotin-dependent enzymes acetyl-coenzyme A carboxylase (ACC; EC 6.4.1.2) and propionyl-coenzyme A carboxylase (PCC; EC 6.4.1.3) are present in all species of the five genera comprising theRhizobiaceaewhich were examined. Evidence is presented that the ACC and PCC activities detectable inRhizobium etliextracts are catalysed by a single acyl-coenzyme A carboxylase. The enzyme fromR. etlistrain 12-53 was purified 478-fold and displayed its highest activity with propionyl-CoA as substrate, with apparentKmandVmaxvalues of 0·064 mM and 2885 nmol min−1(mg protein)−1, respectively. The enzyme carboxylated acetyl-CoA and butyryl-CoA with apparentKmvalues of 0·392 and 0·144 mM, respectively, andVmaxvalues of 423 and 268 nmol min−1(mg protein)−1, respectively. K+,or Cs+markedly activated the enzyme, which was essentially inactive in their absence. Electrophoretic analysis indicated that the acyl-CoA carboxylase was composed of a 74 kDa biotin-containingαsubunit and a 45 kDa biotin-freeβsubunit, and gel chromatography indicated a total molecular mass of 620 000 Da. The strong kinetic preference of the enzyme for propionyl-CoA is consistent with its participation in an anaplerotic pathway utilizing this substrate.
Regulation of ndh expression in Escherichia coli by Fis
Authors: Jackson Laura , Blake Timo , Green Jeffrey
Published: February 2004

The Escherichia coli ndh gene encodes NADH dehydrogenase II, a primary dehydrogenase used during aerobic and nitrate respiration. The anaerobic transcription factor FNR represses ndh expression by binding at two sites centred at −94·5 and −50·5. In vivo transcription studies using promoter fusions with 5′ deletions confirmed that both FNR sites are required for maximum repression under anaerobic conditions. The histone-like protein Fis binds to three sites [centred at −123 (Fis I), −72, (Fis II) and +51 (Fis III)] in the ndh promoter. Using ndh : : lacZ promoter fusions carrying 5′ deletions, or replacement mutations it is shown that Fis III is a repressing site and that Fis I and II are activating sites, with the greatest contribution from Fis II. Deletion of the C-terminal domain of the RNA polymerase α-subunit abolished Fis-mediated activation of ndh expression, suggesting that ndh has a Class I Fis-activated promoter. In accordance with the established pattern of Fis synthesis, ndh transcription was greatest during exponential growth. Thus, it is suggested that Fis enhances ndh expression during periods of rapid growth, by acting as a Class I activator, and that the binding of tandem FNR dimers represses ndh expression by preventing interaction of the RNA polymerase α-subunit with DNA and Fis.
Convergent Evolution of Disease Resistance Gene Specificity in Two Flowering Plant Families[W]
Authors: Ashfield Tom , Ong Laura E. , Nobuta Kan , Schneider Christopher M. , Innes Roger W.
Published: February 2004

Plant disease resistance (R) genes that mediate recognition of the same pathogen determinant sometimes can be found in distantly related plant families. This observation implies that some R gene alleles may have been conserved throughout the diversification of land plants. To address this question, we have compared R genes from Glycine max (soybean), Rpg1-b, and Arabidopsis thaliana, RPM1, that mediate recognition of the same type III effector protein from Pseudomonas syringae, AvrB. RPM1 has been cloned previously, and here, we describe the isolation of Rpg1-b. Although RPM1 and Rpg1-b both belong to the coiled-coil nucleotide binding site (NBS) Leu-rich repeat (LRR) class of R genes, they share only limited sequence similarity outside the conserved domains characteristic of this class. Phylogenetic analyses of A. thaliana and legume NBS-LRR sequences demonstrate that Rpg1-b and RPM1 are not orthologous. We conclude that convergent evolution, rather than the conservation of an ancient specificity, is responsible for the generation of these AvrB-specific genes.
In-Depth Analysis of the Thylakoid Membrane Proteome ofArabidopsis thalianaChloroplasts: New Proteins, New Functions, and a Plastid Proteome Database[W]
Authors: Friso Giulia , Giacomelli Lisa , Ytterberg A. Jimmy , Peltier Jean-Benoit , Rudella Andrea , Sun Qi , Wijk Klaas J. van
Published: February 2004

An extensive analysis of the Arabidopsis thaliana peripheral and integral thylakoid membrane proteome was performed by sequential extractions with salt, detergent, and organic solvents, followed by multidimensional protein separation steps (reverse-phase HPLC and one- and two-dimensional electrophoresis gels), different enzymatic and nonenzymatic protein cleavage techniques, mass spectrometry, and bioinformatics. Altogether, 154 proteins were identified, of which 76 (49%) were α-helical integral membrane proteins. Twenty-seven new proteins without known function but with predicted chloroplast transit peptides were identified, of which 17 (63%) are integral membrane proteins. These new proteins, likely important in thylakoid biogenesis, include two rubredoxins, a potential metallochaperone, and a new DnaJ-like protein. The data were integrated with our analysis of the lumenal-enriched proteome. We identified 83 out of 100 known proteins of the thylakoid localized photosynthetic apparatus, including several new paralogues and some 20 proteins involved in protein insertion, assembly, folding, or proteolysis. An additional 16 proteins are involved in translation, demonstrating that the thylakoid membrane surface is an important site for protein synthesis. The high coverage of the photosynthetic apparatus and the identification of known hydrophobic proteins with low expression levels, such as cpSecE, Ohp1, and Ohp2, indicate an excellent dynamic resolution of the analysis. The sequential extraction process proved very helpful to validate transmembrane prediction. Our data also were cross-correlated to chloroplast subproteome analyses by other laboratories. All data are deposited in a new curated plastid proteome database (PPDB) with multiple search functions (http://cbsusrv01.tc.cornell.edu/users/ppdb/). This PPDB will serve as an expandable resource for the plant community.
TheYABBYGeneDROOPING LEAFRegulates Carpel Specification and Midrib Development inOryza sativa [W]
Authors: Yamaguchi Takahiro , Nagasawa Nobuhiro , Kawasaki Shinji , Matsuoka Makoto , Nagato Yasuo , Hirano Hiro-Yuki
Published: February 2004

In this article, we report that carpel specification in the Oryza sativa (rice) flower is regulated by the floral homeotic gene DROOPING LEAF (DL) that is distinct from the well-known ABC genes. Severe loss-of-function mutations of DL cause complete homeotic transformation of carpels into stamens. Molecular cloning reveals that DL is a member of the YABBY gene family and is closely related to the CRABS CLAW (CRC) gene of Arabidopsis thaliana. DL is expressed in the presumptive region (carpel anlagen), where carpel primordia would initiate, and in carpel primordia. These results suggest that carpel specification is regulated by DL in rice flower development. Whereas CRC plays only a partial role in carpel identity, DL may have been recruited to have the more essential function of specifying carpels during the evolution of rice. We also show that DL interacts antagonistically with class B genes and controls floral meristem determinacy. In addition, severe and weak dl alleles fail to form a midrib in the leaf. The phenotypic analysis of dl mutants, together with analyses of the spatial expression patterns and ectopic expression of DL, demonstrate that DL regulates midrib formation by promoting cell proliferation in the central region of the rice leaf.
Activation of Gibberellin Biosynthesis and Response Pathways by Low Temperature during Imbibition of Arabidopsis thaliana Seeds[W]
Authors: Yamauchi Yukika , Ogawa Mikihiro , Kuwahara Ayuko , Hanada Atsushi , Kamiya Yuji , Yamaguchi Shinjiro
Published: February 2004

Exposure of imbibed seeds to low temperature (typically 4°C) is widely used to break seed dormancy and to improve the frequency of germination. However, the mechanism by which temperature accelerates germination is largely unknown. Using DNA microarray and gas chromatography–mass spectrometry analyses, we found that a subset of gibberellin (GA) biosynthesis genes were upregulated in response to low temperature, resulting in an increase in the level of bioactive GAs and transcript abundance of GA-inducible genes in imbibed Arabidopsis thaliana seeds. Using a loss-of-function mutant, the cold-inducible GA biosynthesis gene, AtGA3ox1, was shown to play an essential role in mediating the effect of low temperature. Besides temperature, AtGA3ox1 also is positively regulated by active phytochrome and negatively regulated by GA activity. We show that both red light and GA deficiency act in addition to low temperature to elevate the level of AtGA3ox1 transcript, indicating that multiple signals are integrated by the AtGA3ox1 gene to control seed germination. When induced by low temperature, AtGA3ox1 mRNA was detectable by in situ RNA hybridization in an additional set of cell types relative to that in red light–induced seeds. Our results illustrate that the GA biosynthesis and response pathways are activated during seed imbibition at low temperature and suggest that the cellular distribution of bioactive GAs may be altered under different light and temperature conditions.
Mutations in thepale aleurone color1Regulatory Gene of theZea maysAnthocyanin Pathway Have Distinct Phenotypes Relative to the Functionally SimilarTRANSPARENT TESTA GLABRA1Gene inArabidopsis thaliana [W]
Authors: Carey Charles C. , Strahle Josie T. , Selinger David A. , Chandler Vicki L.
Published: February 2004

The pale aleurone color1 (pac1) locus, required for anthocyanin pigment in the aleurone and scutellum of the Zea mays (maize) seed, was cloned using Mutator transposon tagging. pac1 encodes a WD40 repeat protein closely related to anthocyanin regulatory proteins ANTHOCYANIN11 (AN11) (Petunia hybrida [petunia]) and TRANSPARENT TESTA GLABRA1 (TTG1) (Arabidopsis thaliana). Introduction of a 35S-Pac1 transgene into A. thaliana complemented multiple ttg1 mutant phenotypes, including ones nonexistent in Z. mays. Hybridization of Z. mays genomic BAC clones with the pac1 sequence identified an additional related gene, mp1. PAC1 and MP1 deduced protein sequences were used as queries to build a phylogenetic tree of homologous WD40 repeat proteins, revealing an ancestral gene duplication leading to two clades in plants, the PAC1 clade and the MP1 clade. Subsequent duplications within each clade have led to additional WD40 repeat proteins in particular species, with all mutants defective in anthocyanin expression contained in the PAC1 clade. Substantial differences in pac1, an11, and ttg1 mutant phenotypes suggest the evolutionary divergence of regulatory mechanisms for several traits that cannot be ascribed solely to divergence of the dicot and monocot protein sequences.
Practices of Implementation of Sexual Harassment Policies: Individual Versus Collective Strategies1
Authors: ZIPPEL KATHRIN
Published: February 2004

abstract This article examines the implementation of sexual harassment law in the workplace in Germany and the United States. Both countries have developed different approaches to the issue, with certain trade‐offs for the pursuit of gender equality and changes in gender workplace culture. Germany has developed a corporatist, collective strategy. Yet, few German employers have adopted policies and training programs. New policy approaches focus on sexual harassment as a group‐based, but gender‐neutral, issue in the context of general unfair workplace practices of “mobbing.” In contrast, sexual harassment is primarily understood as an individual rights issue in the U.S. This approach emphasizes individual (internal) redress. Social and organizational change comes at a high cost for individuals who have been harassed. Employers’ practices in both countries have turned sexual harassment into a gender‐neutral issue. I conclude that a synthesis of both individual and collective approaches with an explicit focus on gender inequality would be desirable.
Gender, Policy, Politics, and Work: Feminist Comparative and Transnational Research
Authors: GOTTFRIED HEIDI , REESE LAURA
Published: February 2004

abstract This article reviews feminist comparative and transnational research on workplace policy, politics and the state. The first section examines a range of theoretical approaches to the topic. We then present a variety of methodologies for conducting comparative and transnational research on policy developments. Informed by a number of case studies included in the symposium, we explore the dynamics and determinants, both national and supranational, of policy formation and its impacts. Finally, we tease out the implicit and explicit notions of gender equity for future policy analysis.
Parental Leave and Gender Equality: Lessons from the European Union
Authors: HAAS LINDA
Published: February 2004

abstract This article describes the development of European Union parental leave policy and its impact on mothers’and fathers’access to parental leave in the individual nations that make up the union. Cross‐national variations in parental leave policy are described and analyzed. Although the 15 countries belonging to the EU in 2002 are concerned about helping working parents reconcile employment and family responsibilities, so far, only one—Sweden—has begun to develop a parental leave policy likely to facilitate men's and women's sharing of responsibility for breadwinning and child care.
Legislating for Economic Sclerosis: Are Lawyers a Baleful Influence on Growth Rates?
Authors: Cameron Sam , Thorpe Andy
Published: February 2004

William Easterly, an ex‐World Bank economist and widely respected growth theorist, in recently noting that skilled individuals may elect to pursue occupations that redistribute income rather than enhance growth, referred to ‘the somewhat whimsical piece of evidence … that economies with lots of lawyers grow more slowly than economies with lots of engineers’. The remark alluded to an assertion by the Bush‐Quayle camp during the 1992 Presidential campaign that too many lawyers were prejudicial to US economic growth, and sparked a heated debate that was played out in the Wall Street Journal and a number of academic journals at the time. A decade later, Easterly's rejoinder has prompted us to examine the view that occupational capture (the capture of talent by particular occupations) can contribute to economic stagnation, by revisiting the notion of lawyers as negative externalities to the growth process.
Do Public Subsidies Complement Business R&D? A Meta‐Analysis of the Econometric Evidence
Authors: García‐Quevedo José
Published: February 2004

Analysis of the effects of public financing on private investment in R & D has been the object of numerous applied studies without it having been possible to arrive at a definite conclusion. In this paper the results of a meta‐regression of econometric evidence on the relationship between public funding of R & D and private R & D expenditures is presented. After the creation of a data‐base including all relevant studies and their results and characteristics, a meta‐analysis was carried out to examine whether the characteristics of the applied analysis influence the results and explain the differences in the empirical literature on this subject.
Family Matters: The Influence of Applied Linguistics and Composition Studies on Second Language Writing Studies—Past, Present, and Future
Authors: Silva Tony , Leki Ilona
Published: February 2004

This intellectual history of the disciplinary roots of second language (L2) writing research and pedagogy in English examines the influences of its feeder disciplines, composition studies and applied linguistics, and their parent disciplines, rhetoric and linguistics. After a brief history of L2 writing's two grandparent disciplines (rhetoric and linguistics) and its two parent disciplines (composition studies and applied linguistics), the article focuses on the effect of the two parent disciplines' conflicting identities. Whereas L2 writing benefits from its invigorating position at the confluence of these two intellectual streams, it has also been pulled in different incompatible directions resulting from differences, and even similarities, between applied linguistics' and composition studies' inquiry paradigms and traditions, their intellectual identities, and the material disciplinary manifestations of their organizations, conferences, and publications. A brief history of L2 writing pedagogy and research demonstrates the push and pull of the conflicting influences of its feeder disciplines.
MLJ Reviews
Authors: Liskin‐gasparro Judith E.
Published: February 2004

BOXER, DIANA. Applying Sociolinguistics: Domains and Face‐to‐Face Interaction.

COOK, VIVIAN. (Ed.). Portraits of the L2 User.

FERRIS, DANA J.
Treatment of Error in Second Language Student Writing.

LIU, JUN, & JETTE G. HANSEN.
Peer Response in Second Language Writing Classrooms.

GASS, SUSAN, KATHLEEN BARDOVI–HARLIG, SALLY SIELOFF MAGNAN, & JOEL WALZ. (Eds.). Pedagogical Norms for Second and Foreign Language Learning and Teaching.

OSBORN, TERRY A. (Ed.). The Future of Foreign Language Education in the United States.

REAGAN, TIMOTHY G., & TERRY A. OSBORN. The Foreign Language Educator in Society: Toward a Critical Pedagogy.

ROBINSON, PETER. (Ed.).
Individual Differences and Instructed Language Learning.

SAVIGNON, SANDRA J. (Ed.). Interpreting Communicative Language Teaching: Contexts and Concerns in Teacher Education.

SCHMITT, NORBERT. (Ed.). An Introduction to Applied Linguistics.

SCHOFER, PETER. Text as Culture: Teaching through Literature and Language.

TOCHON, FRANÇOIS. (Ed.). The Foreign Self: Truth Telling as Educational Inquiry.

WALLINGER, LINDA M. (Ed.). Teaching in Changing Times: The Courage to Lead.

JUBB, MARGARET. Upgrade Your French.

BINAMÉ, JOSÉ J., & PAUL G. SOCKEN.
The French They Never Taught You: Tips for Teachers and Advanced Students.

STEELE, ROSS. Civilisation progressive du français avec 300 activités.

STEELE, ROSS. Civilisation progressive du français: Livret de corrigés.

VALDMAN, ALBERT, CATHY PONS, MARY ELLEN SCULLEN, & SARAH JOURDAIN. Chez Nous: Branché sur le Monde Francophone (with activity CD–ROM).

BRETTLER, MARC ZVI. Biblical Hebrew for Students of Modern Israeli Hebrew.

ZILKHA, AVRAHAM. Modern English–Hebrew Dictionary.

TOLLEFSON, JAMES W. (Ed.). Language Policies in Education: Critical Issues.

PERINI, MÁRIO A.
Modern Portuguese: A Reference Grammar.

CUBBERLEY, PAUL. Russian: A Linguistic Introduction.

LEVINE, ESTHER L., & CONSTANCE M. MONTROSS. Vistas y voces latinas.

GILL, MARY MCVEY, DEANA SMALLEY, & MARÍA PAZ HARO. (Eds.). Cinema for Spanish Conversation.

SAMANIEGO, FABIÁN A., THOMAS J. BLOMMERS, MAGALY LAGUNAS‐SOLAR, VIVIANE RITZI‐MAROUF, & FRANCISCO RODRÍGUEZ. ¡Dimelo tú!

WHITLEY, M. STANLEY.
Spanish/English Contrasts: A Course in Spanish Linguistics.

BROWN, JAMES DEAN, THOM HUDSON, JOHN NORRIS, & WILLIAM J. BONK. An Investigation of Second Language Task‐Based Performance Assessments.
In vitro penetration of bleaching agents into the pulp chamber
Authors: Benetti A. R. , Valera M. C. , Mancini M. N. G. , Miranda C. B. , Balducci I.
Published: February 2004

Aim  To investigate pulp chamber penetration of bleaching agents in teeth following restorative procedures.

Methodology  Bovine lateral incisors were sectioned 3 mm apical to the cemento‐enamel junction and the coronal pulpal tissue was removed. Teeth were divided into six groups (n = 10): G1, G2 and G3 were not submitted to any restorative procedure, while G4, G5 and G6 were submitted to Class V preparations and restored with composite resin. Acetate buffer was placed in the pulp chamber and treatment agents were applied for 60 min at 37 °C as follows: G1 and G4, immersion into distilled water; G2 and G5, 10% carbamide peroxide (CP) exposure; G3 and G6, 35% CP bleaching. The buffer solution was removed and transferred to a glass tube where leuco crystal violet and horseradish peroxidase were added, producing a blue solution. The optical density of the blue solution was determined spectrophotometrically at 596 nm. A standard curve made with known amounts of hydrogen peroxide was used to convert the optical density values of the coloured samples into microgram equivalents of hydrogen peroxide. Data were submitted to anova and Tukey's test (5%).

Results  Amounts of hydrogen peroxide found in the pulp chamber of G2 and G5 specimens (0.1833 ± 0.2003 µg) were significantly lower (P = 0.001) when compared to G3 and G6 specimens (0.4604 ± 0.3981 µg). Restored teeth held significantly higher (P = 0.001) hydrogen peroxide concentrations in the pulp chamber than intact teeth.

Conclusion  Higher concentrations of the bleaching agent produced higher levels of hydrogen peroxide in the pulp chamber, especially in restored teeth.
Gingival necrosis following the use of a paraformaldehyde‐containing paste: a case report
Authors: Özgöz M. , Yaǧiz H. , Çiçek Y. , Tezel A.
Published: February 2004

Aim  To report on an unusual case of gingival necrosis following the use of a paraformaldehyde‐containing paste in root canal treatment.

Summary  Paraformaldehyde preparations are toxic to hard and soft tissues. In an era of effective local anaesthesia, toxic devitalizing preparations have few applications. However, in a mobile world population, severe tissue injury may occasionally be encountered after the use of paraformaldehyde or other toxic agents in some parts of the world. Dentists should avoid such preparations and be alert of the features and management of local toxicity if they encounter it in practice.

Key learning points 

Paraformaldehyde‐containing pastes have no application in contemporary dentistry.

Dentists should avoid toxic preparations for pulp devitalization.

Dentists should be aware of the features and management of tissue necrosis resulting from the use of toxic dressing materials.
Viral gastroenteritis – a danger to the patient, a danger to the staff
Authors: Appelboam R. , Hammond E.
Published: February 2004

Viral gastroenteritis is usually a mild, self‐limiting illness. We report a case of a previously well 74‐year‐old woman who suffered a grave complication of this common condition, and caused a significant outbreak of illness amongst staff involved in her care. This case highlights the risks of Hospital Acquired Infection and raises important infection control issues. It illustrates the hazards associated with exposure to potentially infectious secretions and presents a clear message to medical and nursing staff involved in the care of the acute surgical emergency.
Thrombocytopenia in the parturient
Authors: Kam P. C. A. , Thompson S. A. , Liew A. C. S.
Published: February 2004

Thrombocytopenia in pregnant women can be associated with substantial maternal and neonatal morbidity. It may result from a range of conditions and early implementation of some specific treatment may improve both maternal and neonatal outcome. In this review we discuss the clinical features of the more common causes of thrombocytopenia associated with pregnancy, and provide an overview of the anaesthetic considerations.
Local anaesthesia and sedation for rigid bronchoscopy for emergency relief of central airway obstruction
Authors: Conacher I. D. , Curran E.
Published: February 2004

We report three experiences that illustrate the use of local anaesthesia for rigid bronchoscopy. All patients were acute emergencies, with life‐threatening central airway problems. Instruments were inserted after the airway was anaesthetised using a technique that owes much to mid 20th Century methods for inserting endobronchial blockers. There is discussion about requirement to preserve and conserve self‐ventilation and the securing of compromised central airways without the aid of neuromuscular blocking agents. Historical aspects of bronchoscopy are reviewed. Concomitant sedation reduced the unpleasantness of the experience in a way that in the past could only be dealt with by careful attention to the humanitarian elements of detail. Problems of oxygenation were ameliorated by periodically superimposing intermittent jetting with a Sanders injector fed from the oxygen pipeline. A need for developing and refining topical and other local anaesthetic techniques for rigid bronchoscopy is anticipated with the expansion of services for tracheo‐bronchial stenting and lasering.